Facilitation of pattern recognition by cuing foveation with the luminance centroid as origin of the frame of reference.

The strategy for visual information processing must vary with the specific situation. We assume that in recognition of pre-learnt letter-like patterns under time-pressure conditions, mechanisms of selective attention are involved. We propose that, with simple stimuli, foveation is to the luminance centroids of such patterns, and if normally the latter has to be computed by the brain, cuing such information should improve performance. This assumption was tested on three subjects with five stimuli. In confirmation of the working hypothesis, we found significant improvements in performance (P = 0.01 or better) for each of the stimuli, with cuing to 'relevant' as compared with 'irrelevant' sites, and also when the point of foveation was nearer to the 'nodal' site. It is concluded that in pattern recognition processes, nodal regions are computed, the luminance centroid for example, for simple pattern stimuli.


Binocular chromatic rivalry and single vision.

Depth perception is known to be impaired for chromatic equiluminant patterns. To investigate this phenomenon I have compared the effects of binocularly presented stimuli in the form of stripes, which contain only luminance information with similarly presented stimuli which contain only chromatic information. Observations of the reported percepts for the two conditions demonstrate that mechanisms of colour vision can impede stereopsis based on binocular fusion when the chromatic stripes are at, or even near, equiluminance, provided that their saturation is high. This observation is consistent with inhibitory interactions within the chromatic-sensitive neuronal groupings in the visual cortex.


Visual evoked electrical and magnetic response to half-field stimulation using pattern reversal stimulation.

The visual evoked magnetic response to half-field stimulation using pattern reversal was studied using a d.c. SQUID coupled to a second order gradiometer. The main component of the magnetic response consisted of a positive wave at around 100 ms (P100M). At the time this component was present the response to half-field stimulation consisted of an outgoing magnetic field contralateral and extending to the midline. When the left half field was stimulated the outgoing field was over the posterior right visual cortex and when the right half field was stimulated it was over the left anterior visual cortex. These findings would correctly identify a source located in the contralateral visual cortex. The orientation of the dipoles was not that previously assumed to explain the paradoxical lateralization of the visual evoked potential. The results are discussed in terms of both electrical and magnetic models of the calcarine fissure.


Rules for colour constancy.

Colours of objects tend to be constant regardless of the colour of the illuminant, therefore, regardless of the quanta catch of the retinal cones. Various mechanisms for this including context recognition, adaptation of retinal sensitivities and independent processing by receptor types have been proposed. These present experiments test the hypothesis that colours are determined by the normalized relationship between all colours in the field of view. In this hypothesis, colours are constant in classical experiments simply because changes of the illuminant do not disrupt the relationship between quanta catches across the field of view. The experiments consist of making sets of colour displays; each with the same relative quanta catches, but different absolute reflectances. 'Colour tautomi' arrays of five colour patches were printed using controlled amounts of yellow, magenta, cyan and black toners. The experiment began with a control 'colour tautomi' array of reflectances with measured relative quanta catches. New arrays of colours were then chosen that increased (or decreased) the reflectances, and quanta catches, a constant amount for the entire array. These changes were done independently for each receptor type. When these 'colour tautomi' are viewed in the room, each array has a different set of colours. When viewed in a restricted field of view, all arrays appear the same. In a further experiment new areas such as white are added to the display. Colour constancy is a field phenomenon controlled by the relative quanta catches in the field of view. Absolute colour constancy is controlled by the relative quanta catches in the field of view and the absolute quantum catches of the receptors.


Springer's lines and Hermann's grid.

Hermann's grid is a complete matrix of black squares; Springer's figure has alternate squares whited out. Both figures generate illusory elements, bright and dark lines in the white spaces, with different elements seen from different distances. The visibility of these different elements is shown to be related to the detectability of sinusoidal gratings of wavenumbers corresponding to certain critical components of the Fourier decomposition of the figure. Evidence from the detection of gratings shows that near- and sub- (but not supra-) threshold contrasts are subject to a fourth power compression which shows, in the present figures, as a defect in the percept, equivalent to the deletion of (a part of) the corresponding Fourier components. There are some residual problems in understanding the perception of Hermann's grid.


Mutual rod-cone suppression within the central visual field.

Under mesopic conditions the contrast sensitivity of the central visual field is reduced as the result of a non-linear interaction between rod- and cone-mediated signals, each of which is capable of higher sensitivity in isolation. The interaction is produced only when the rod-mediated system is driven at flicker rates above 6 Hz. This finding bears upon how rod and cone signals are combined and therefore affects our interpretation of the significance of the relationship between retinal illuminance and both contrast sensitivity and temporal resolution.


Using distinctive Fourier components to discriminate between complex patterns.

Observers discriminated between a plaid pattern formed by summing vertical and horizontal cosine gratings, and a plaid formed by multiplying the gratings. Such patterns are alike with respect to many non-Fourier primitives, but differ in the Fourier domain by diagonal components which are present in the plaid formed by multiplication, but not in the one formed by summing. When discrimination performance is related to the contrast of the diagonal components, it is found that the contrast threshold for discrimination is approximately the same as the threshold for detection of the isolated components. However, the psychometric function for discrimination is shallower than that for detection, suggesting the presence of masking. Despite the masking, the results support the proposition that discrimination processes may operate directly on the representations of local Fourier components.


Image enhancement filters significantly improve reading performance for low vision observers.

As people age, so do their photoreceptors; many photoreceptors in central vision stop functioning when a person reaches their late sixties or early seventies. Low vision observers with losses in central vision, those with age-related maculopathies, were studied. Low vision observers no longer see high spatial frequencies, being unable to resolve fine edge detail. We developed image enhancement filters to compensate for the low vision observer's losses in contrast sensitivity to intermediate and high spatial frequencies. The filters work by boosting the amplitude of the less visible intermediate spatial frequencies. The lower spatial frequencies. These image enhancement filters not only reduce the magnification needed for reading by up to 70%, but they also increase the observer's reading speed by 2-4 times. A summary of this research is presented.


Interactions between colour and luminance contrast in the perception of motion.

It has been demonstrated widely that at isoluminance moving chromatic stimuli are seen to be stationary or moving more slowly than their luminance counterparts. We have examined the effect on perceived velocity of adding luminance contrast to an isoluminant chromatic stimulus. We show that moving luminance contrast 'captures' colour so that a combined colour and luminance stimulus is seen moving as a unified percept. However, in the presence of colour contrast, significantly higher levels of luminance contrast are required to achieve a veridical velocity than for monochromatic stimuli with only luminance contrast. We show that this interactive effect between colour and luminance contrast cannot be fully explained by a threshold masking of luminance by colour contrast. The effect suggests that a breakdown in the veridical perception of velocity should be expected for colours with a wide range of associated luminance contrasts and not just for those at the point of isoluminance.


Use of interferometric visual stimulators in optometry.

Professor Fergus Campbell and colleagues pioneered the use of the interferometric visual stimulator as a tool for separating optical from neural factors which limit spatial vision. The device is now commercially available as a clinical instrument which 'bypasses the optics of the eye' to measure the potential visual acuity of the neural portion of the visual system. However, the clinician needs to be aware of limitations of current instrument designs and recent advances in our understanding of peripheral vision, to correctly interpret patient data gathered with these devices.


Visual responses to reward-related cues in inferior parietal lobule.

A sample of 263 neurones was recorded in area 7a of the parietal lobe, in a monkey performing a reach task to visual targets displayed on a touch-sensitive videomonitor. The task had been operantly conditioned on food or juice rewards, and 78 (30%) of the units showed activity changes linked in some way to the reward. For most of these cells, the response was to the approach of the trainer's hand with the food reward. This specific visual response was similar irrespective of the direction of approach. Six cells increased discharge as soon as the task was completed in apparent anticipation of the reward. Another two neurones responded to missing a reward: they fired vigorously if the videoscreen was blanked in mid-trial because a target was not correctly touched. In many cases (40/78) the same cells responding to some aspect of the reward also responded to visual cues given during the task, especially the presentation of the target location. Reward-related activity in area 7a probably results from an integration of the visual and limbic inputs to this region, such that visual information which foretells behaviourally important events is emphasized.


Orientation anisotropy: some caveats in interpreting group differences and developmental changes.

We tested 220 children aged 7-12 yr and 20 university students for visual contrast sensitivity at spatial frequencies of 1.2-21.9 c/deg for vertical, horizontal and oblique sinusoidal gratings. Males had higher mean sensitivity then females and adults had higher mean sensitivity than children. Sensitivity was greater for cardinal than oblique orientations, and this oblique effect increased with spatial frequency and mean sensitivity, and with age in children. Developmental growth of oblique anisotropy can be explained by growth in contrast sensitivity. Different sizes of oblique effect were found between groups living in different locations, but variations were mainly linked to differences in age and contrast sensitivity. Genetic or environmental interpretations of group differences should be treated with caution. Other anisotropies occurred (horizontal was better than vertical and right than left obliques), but these differences were small and irregular and may represent response biases rather than neurological effects.


Coloured shadows described in a cone contrast space.

Two effects which can modify the appearance of a colour seen in a context compared to isolation are chromatic induction and colour constancy. These effects transform colour in ways which depend on the visual system rather than physical characteristics of light and surfaces. They need not reflect different processes within the visual system, indeed, chromatic induction has been attributed to the same processes as those involved in constancy, or, as an error of the visual system attempting to achieve constancy. This hierarchy is not necessary: both constancy and induction may result from the same processes without requiring that one promotes the other or that constancy is a goal of the visual system. This study examines induction in terms of cone contrasts in a coloured shadow display, part of a study to establish a relevant measure of contrast and its role in chromatic induction and colour constancy.


Colour, contrast and the visual evoked potential.

Visual evoked potentials exhibit interesting morphological changes when they are elicited by checkerboards of different spatial and chromatic contrast, counterphasing in the foveal and lower macula field. The characteristic, positive wave of the phase-reversal visual evoked potential, for example, is preceded by an increasingly prominent negative peak as luminance contrast progressively increases above 10% and, at isoluminance, the response to red and green checkerboards becomes a predominantly monophasic negative wave. To study the nature of the morphological change we synthesized these waveforms with a computer simulation consisting of Gaussian components. The amplitudes of positive and negative components were altered until the synthesized response was closely similar to the recorded data. These Gaussian components have response characteristics which are identified with those of magnocellular and parvocellular neurones.


Amplitude spectra of natural images.

Several studies have suggested that the amplitude spectra of photographs of natural scenes are remarkably similar and have the form: amplitude varies; is directly proportional to spatial frequency-1.0. This is, of course, a straight line with slope of -1.0 when plotted on double logarithmic coordinates. We have examined the amplitude spectra of 135 digitized photographs of natural scenes and have found that relatively few images conform exactly to the suggestion. About 25% of the images in our sample have spectra which show significant curvature when plotted on log-log coordinates. The best-fitting regression lines have slopes that range from -0.8 to -1.5; the average slope is -1.2, rather steeper than previously suggested.


Different spatial tunings for ON and OFF pathway stimulation.

We compared the spatial tuning of sensitivity to luminance increments and decrements in three types of localized stimulus presentation with a smooth spatiotemporal envelope. The first type consisted of spatiotemporal Gabor grating functions with either a positive or a negative bias in luminance. The spatial tuning showed a substantially narrower bandwidth and greater peak sensitivity for the positive Gabors. A similar description could be applied to the results for detection of spots with a 2-D difference-of-Gaussian profile, although the shape of the tuning function differed in several respects. We also used the biased Gabor modulation in a contrast self-masking paradigm, where the increment (or decrement) was presented against a steady background with the same spatial configuration, over a range of base contrasts. At medium spatial frequencies the biased masking functions were similar to those typically found for unbiased gratings, in showing a threshold facilitation (dipper) at low contrast, and sub-Weber masking behaviour at higher contrasts. At low spatial frequencies, however, a pronounced asymmetry appeared. Stimuli with a positive bias again showed typical masking behaviour, but a virtually flat masking function was obtained for negative bias stimuli. We conclude that stimuli without abrupt luminance transients reveal pronounced differences in the spatial tuning of responses to positive and negative stimuli, which probably reflect differences in the neural connectivity of the ON and OFF processing systems.


Effect of myelination on the conduction velocity of optic nerve fibres.

It was proposed by Rushton in 1951, from theoretical considerations, that myelinated fibres less than 1 micron in diameter would conduct more slowly than unmyelinated fibres of the same size and that myelinated fibres below about 0.7 micron would not conduct at all. The experimental data on which he based his theory are all from the peripheral nervous system where small myelinated fibres are rare, and no experimental verification of Rushton's hypothesis has been attempted. In mammalian optic nerve, nearly all the fibres are myelinated; yet half have diameters below 1 micron, with many below 0.7 micron. The many studies of conduction velocities in the visual system enable a test of Rushton's hypothesis to be made. We have examined the correlations between conduction velocity and fibre diameter from a wide range of published studies of the mammalian visual system. The results of our analysis suggest that the small myelinated fibres of the optic nerve and optic tract conduct action potentials more rapidly than is predicted by Rushton's hypothesis, while the unmyelinated axons within the retina actually conduct more slowly than predicted. There is no reason to believe, in this case, that myelination of a small axon will reduce its conduction velocity.


Problems measuring contrast sensitivity in children.

A preliminary study measured the contrast sensitivity function (CSF) in 30 children (aged 3 months-5 years). Preferential looking techniques were used to assess CSF to sine wave gratings displayed on one of two screens. To find a meaningful contrast sensitivity procedure we compared the results with a shorter procedure using an edge stimulus. The following problems were encountered: measuring the contrasts required to detect four or five different spatial frequencies took time, resulting in boredom and loss of attention in our subjects; there was poor correlation between CSF and edge detection; an interesting artefact resulted in a plateau rather than a low frequency fall-off in the CSF of five of the children greater than 30 months old. This artefact may have resulted from peripheral rather than central retinal responses and/or motion artefacts in the stimulus onset. A follow up study with 41 additional children aged 3-36 months limited the contrast testing to that of the spatial frequency corresponding to the peak of the CSF. The shortened procedure, plus a lot of encouragement, resulted in higher contrast sensitivities in all but the oldest age group and successful monocular contrast measurements. In order to avoid artefacts arising from peripheral vision, children were encouraged to look at each screen before responding.


New acuity test for toddlers.

Preferential looking is the technique of choice for measuring visual acuity in infants and young children. Most workers agree that the toddler age group, 1 to 3 years, is the most difficult to test. This is because of their short attention span and restlessness, but mostly because they find the grating target used in the test, frankly boring. The concept of the vanishing optotype chart offers alternative test targets, while utilizing the technique of preferential looking. We have designed a test which comprises a familiar shape (house, car etc.) on the upper or lower part of a neutral grey card. The shape is computer generated, and designed to fade completely when beyond the resolution limit. Acuity is determined by the width of the white lines making up the shape. As with conventional preferential looking, the observer notes the child's eye movements to determine the position of the target shape. Although picture naming is not required, the shapes help to maintain the child's interest in the test. The test is quick, and is successful with the toddler age group and older patients with intellectual impairment.


Current perspective on microfluctuations of accommodation.

The collaboration of Fergus Campbell, Gerald Westheimer and John Robson in the 1950s produced insight into the nature of accommodation microfluctuations and instigated work which has led to the current view that the nominally steady-state accommodation response exhibits temporal variations which can be characterized by two dominant regions of activity: a low-frequency component (LFC less than 0.6 Hz) and a high-frequency component (HFC greater than or equal to 1.0 less than or equal to 2.3 Hz). A functional role has been attributed to these microfluctuations as they offer a means by which a directional cue could be derived from an even-error stimulus. However, there is no consensus regarding the respective contribution made by each of the dominant components in the accommodation control process. Using a newly-designed measurement and recording system we have conducted a series of experiments to investigate the nature and aetiology of the microfluctuations. The incidence and magnitude of microfluctuations in LFCs and HFCs for central and peripheral lens zones were investigated while five young emmetropic subjects viewed a near target. The form of the power spectra of the fluctuations was found to be similar for central and peripheral zones although an overall reduction in magnitude was observed in the periphery. The HFCs are thus a consistent feature of microfluctuations in central zones and not, as previously suggested, merely a spurious feature of peripheral zones. A significant between-subject variation in the location of HFCs was found and led us to consider the relationship between HFCs and other physiological systems which provide intraocular rhythmic variation.(ABSTRACT TRUNCATED AT 250 WORDS)


Preliminary observations concerning treatment of visual discomfort and associated perceptual distortion.

A system for therapeutic precision tinting is described. Some individuals who are subject to perceptual distortion of text no longer perceive the distortion when the text has a particular colour. A simple colorimeter enables an observer to illuminate text with light of a particular chromaticity, varying first CIE 1976 hue angle (huv), then saturation (suv), and then luminance, to obtain a setting that maximizes visual comfort and reduces any perceptual distortion. The colorimeter setting is then matched by a combination of tinted trial lenses. The combination uses only two dyes at a time from a selection of seven, unless a dark lens is required, when a third neutral (grey) dye is added. The subject observes both text and a normal scene when wearing tinted trial lenses. A variety of trial lenses are compared including those that match the colorimeter setting and others with similar hue angle. Spectacle lenses are then tinted so as to have a spectral transmission identical to that of the chosen combination of trial lenses. Certain patients with reading disorders, eye-strain, headaches or photosensitivity epilepsy report benefit when wearing spectacles tinted according to the above techniques. The physiological basis for the therapeutic effects is uncertain, but may involve a selective impairment of luminance or colour-difference channels.


Dependence of stereomotion on the orientation of spatial-frequency components.

It is known that sensitivity to stereoscopic motion in depth is not based upon the fine analysis of static disparities but instead is based on the binocular combination of motion-sensitive mechanisms. We show in this paper that an 'aperture problem' arises for the analysis of motion in depth, just as it does for monocular motion sensitivity. We extend Adelson and Movshon's solution to the aperture problem by intersection of perpendicular constraints to the three-dimensional case, and show that it predicts velocity matches for oblique gratings moving in depth, for orientations close to vertical. We show that binocular plaids give rise to motion in depth when the component orientations match in each eye, and the monocular motions are horizontal. The match velocities are consistent with intersection of perpendicular constraints. In three dimensions intersection of perpendicular constraints may be necessary, but is not a sufficient condition for the perception of coherent stereoscopic motion in depth.


Area 21a in the cat and the detection of binocular orientation disparity.

Visual response properties were examined in 115 cells, recorded in area 21a of the cerebral cortex of anaesthetized and paralysed adult cats. Cells were binocular and had receptive fields consisting of a single uniform discharge region which fired with composite ON/OFF responses to stationary flashing stimuli. Most cells were sharply tuned for orientation, but this was unaffected by changes in stimulus length. This result is consistent with a model in which the cells of area 21a receive their input from C cells of the striate cortex. Evidence for this was obtained by studying the decline in the responsiveness in area 21a that accompanied the cooling of areas 17 and 18. There was little indication that the cells of area 21a were effective detectors of spatial disparity, but their sharp monocular orientation tuning and differences in the preferred orientation of ipsilateral and contralateral eyes hinted at a role in the detection of binocular orientation disparity. Our results, however, showed that the recorded binocular disparity curves could be accounted for by summing the two monocular contributions and there was no apparent novel binocular component.


Strategies for constructing a guinea pig organ of Corti cDNA library and its potential use.

Mutations of genes common to several tissues or organs can lead to cellular damage, which may result in hearing impairment as part of a syndromic disorder. Mutations of genes that are unique to the organ of Corti would have a high probability of causing nonsyndromic hearing impairment. It is expected that such genes are involved in auditory transduction as well as in maintaining specific hair cell and supporting cell functions in the organ of Corti. Cloning and describing genes involved with nonsyndromic hearing impairment thus require the construction of a guinea pig cDNA library of the organ of Corti.


Transgenic mice. Current applications to the study of the auditory and vestibular systems.

Understanding the variety of genetic disorders affecting the inner ear demands that we first comprehend the molecular mechanisms involved in its development. Mechanisms of development can best be understood by the study of mutant organisms. Progress in the study of mammalian development has been hampered by the difficulty inherent in the identification and isolation of mutated genes. Transgenic technology provides a direct experimental approach to the study of the control and tissue specificity of gene expression. Additionally, this technology allows new and exciting methods of human disease modeling. A by-product of this technology is the creation of insertional mutants, which provide a unique approach toward the identification of genes involved in a variety of developmental processes including those of hearing and balance.


Genetic alterations in head and neck cancer.

Mutations of the ras gene family appear to be an uncommon genetic alteration in SCCHN. A common region of DNA amplification on chromosome 11q13 has been identified in SCCHN. A cluster of proto-oncogenes (int-2, hst-1, bcl-1, prad-1) has been localized to the 11q13 region. Studies are needed to determine the critical genes in 11q13 whose expression drive the amplicon. Mutations of the p53 tumor suppressor gene are the most common genetic alteration in SCCHN. The hope is that dysregulated oncogenes or tumor suppressor genes may be targets for specific therapy.


Cytogenetics in head and neck cancer.

Cytogenetic analysis of cell lines has identified a number of chromosomal regions that are likely to contain the genes important in malignant transformation in HNSCC. Further work needs to be done comparing results from cells grown in culture with tumors from which they are derived to determine the applicability of cytogenetic analysis. Preliminary results suggest that some of the chromosome changes observed may correlate with a cell's response to radiation and as such could provide a tool for evaluating a patient's response to planned therapy.


Hereditary and environmental factors associated with risk and progression of head and neck cancer.

The familial occurrence of head and neck cancers supports the role of heredity in this disease group. The roles of environmental and genetic factors are difficult to separate. There are several well-characterized entities, however, that are associated with risk and prognosis of head and neck cancer, including Lynch-II syndrome, Bloom syndrome, Fanconi's anemia, xeroderma pigmentosum, ataxia telangiectasia, and Li-Fraumeni syndrome. Mutagen-induced chromosomal damage is associated with an increased risk of multiple primary neoplasms and upper aerodigestive tract cancers. A possible reduction of genotoxicity, mediated by micronutrients, was demonstrated in vitro. Sister chromatid exchanges and micronuclei are useful exposure and disease markers. Metabolic changes (acetylation, DBQ phenotype, and the AH locus polymorphism) have been found to be associated with cancer of the upper aerodigestive tract. Most associations between histocompatibility antigens and solid tumors are relatively weak, probably because of the masking effects of environmental factors. Infections by HPV, EBV, and HSV have a causative or predisposing role in several types of head and neck cancer. Amplification and rearrangement of oncogenes may also play a role in carcinogenesis, and oncogene amplification may be associated with aggressive tumor behavior and unfavorable clinical prognosis. Ploidy of tumors seems to be an important determinant of survival and response to therapy.


The role of peptide growth factors in head and neck carcinoma.

Peptide growth factors are proteins that stimulate cellular proliferation by binding to specific cell membrane receptors. Evidence is accumulating that abnormal regulation of growth factors may contribute to carcinogenesis. The epithelial growth factors, EGF and TGF-alpha, which share the same receptor, EGFR, may play a pivotal role in the development and maintenance of head and neck cancer; preliminary studies concerning TGF-beta and IL-2 are inconclusive. There is increased production of TGF-alpha and EGFR mRNA in the majority of fresh tissues and cell lines from patients with SCCHN. This increase results from transcriptional activation of the gene(s). Therapies directed at the regulation of gene transcription may be useful in chemoprevention or modulation of disease. Nuclear studies that target up-regulated growth factor receptors may improve the ability to detect microscopic regional metastatic disease.


Gene localization by linkage analysis.

Traditional genetic approaches have led to the identification of defects underlying an impressive array of diseases. Genetic terminology, Mendel's laws, chromosomes and linkage, statistical methods for linkage analysis, genetic markers, multilocus mapping, strategies in linkage studies, linkage heterogeneity, and the future of linkage analysis are discussed in this article. The molecular basis for most disorders, however, cannot be gleaned because there is no identifiable primary metabolic disorder.


Gene mapping of the Usher syndromes.

USH is an autosomal recessive group of diseases characterized by auditory impairment and visual loss owing to RP. Two common types of USH are known, types I and II. USH type I is characterized by a congenital severe to profound hearing impairment, absent vestibular function, and a progressive pigmentary retinopathy. Persons with type I do not find hearing aids useful, have delayed motor development, and experience progressive night blindness and peripheral visual loss, which usually begins in their second decade. USH type II is characterized by a congenital moderate to severe hearing loss with a down-sloping audiogram, normal vestibular function, and a progressive pigmentary retinopathy. Persons with USH2 find hearing aids beneficial, have normal psychomotor development, and experience progressive night blindness and peripheral visual loss, which usually begins in their third decade. Vestibular dysfunction is the best distinguishing hallmark to differentiate USH type I from type II. One USH type II gene (called USH2) has been assigned to chromosome 1q. One USH type I gene has been tentatively assigned to chromosome 14q. There are other USH genes that have not yet been localized.


Finding the gene(s) for Waardenburg syndrome(s).

Waardenburg syndrome is a recognizable disorder characterized by autosomal dominant inheritance of pigmentary abnormalities of the eyes, hair, and skin sometimes associated with congenital hearing impairment. At least two different types of Waardenburg syndrome have been described. The different types of Waardenburg syndrome are differentiated as follows: type I, with dystopia canthorum; type II, without dystopia canthorum; and type III, without dystopia, with unilateral eyelid ptosis and skeletal abnormalities. Results of pooled linkage analysis done by a consortium of investigators suggests that Waardenburg syndrome type I is genetically heterogeneous, meaning that there is probably more than one genotype that can be associated with the findings typical of the syndrome. A mutated gene that can cause Waardenburg syndrome type I has been discovered. Either a single base pair substitution or an 18 base pair deletion in exon 2 has been found in affected individuals but is not found in unaffected members. Most likely, the mutated gene causes a perturbation in DNA binding of a paired domain, in turn having an effect on the regulation of other genes so the development and spatial orientation of cells and structures derived from the neural crest are affected. Forty years after Waardenburg syndrome was first described, a mutant gene has been found that is known to cause the syndrome. The process of discovery that has transpired in the time from syndrome description to gene identification has been one of steady progress and interdisciplinary cooperation.(ABSTRACT TRUNCATED AT 250 WORDS)


Genetic counseling for the deaf.

Genetic counseling is a process that emphasizes accurate diagnosis of hereditary conditions and communication of information to families. Genetic counseling involves systematic collection of family and medical history, a physical examination by a certified clinical geneticist, sharing of information with the family, and follow-up and support services. The issues that arise in genetic counseling can differ for every family and are often dependent on the degree of deafness present in the family, age of onset, and linguistic and cultural orientation. It is important for the genetic counselor to consider these factors in the provision of genetic services. With the increasing application of molecular genetics to the diagnosis and management of hereditary deafness and the increasing participation of families with deafness in research studies, the involvement of genetic counselors to provide information and education to consumers as well as medical professionals and researchers is becoming even more critical. The success of genetic counseling for the provision of information to families and the delineation of types of hereditary deafness through clinical and laboratory research is dependent on appropriate referrals by medical professionals, including otolaryngologists. A working relationship between otolaryngologists and clinical geneticists for the referral and evaluation of patients with hereditary deafness or deafness of "unknown" etiology is important.


Genetic aspects of idiopathic speech and language disorders.

At the outset of this article, we posed the question of whether or not the current evidence from genetic studies of DLD and stuttering indicate that it would be fruitful to conduct studies aimed at determining the gene location for each of these disorders. As we pointed out, because these are behavioral development disorders, phenotypic variations and changes in characteristics through the life span pose problems when attempting to determine who is and is not affected. Further, because these disorders can be either idiopathic or secondary to a variety of causes, any genetic study must rule out or take account of cases secondary to other factors. Few studies conducted thus far have taken these problems into account, and the results must be considered tentative. Given these reservations, the results certainly point to a genetic component in both disorders, although the data collected thus far on DLD suggest a mendelian form of transmission. If further more intensive studies continue to support this model for DLD, linkage studies on this disorder are likely to be productive.


[Results of surgical treatment in laryngeal cancer patients based on material of the Lublin Clinic of Otolaryngology].

A group of 287 laryngeal carcinoma patients was discussed, who were operationally treated over the period of ten years (1974-1983). Three- and five-year-long symptomless survivals were presented taking into account: age, sex, environment, habits, development of cancer on the base of precancerous conditions, primary localisation, progression of cancer in the larynx, presence of nodular metastases and a degree of clinical progression. In a group of 206 patients treated only operationally there were 65% of 5-year-long symptomless survivals, in a group 61 patients treated by the combined method--33%, and finally in a group of patients with recurrence after irradiation treated operationally there were only 25% of 5-year-long survivals.


[Investigation of variability in the vascularity of trapezius musculo-cutaneous flaps].

The search on the human body cadavers was done to determine the exact localization of the various cutaneous island flaps depending on the course of the blood vessels. The latex solution stained with the prussian blue was injected directly into the thyro-cervical trunk or subclavian arteries. Afterwards the island musculocutaneous flaps from various regions of the trapezius muscle were performed. The whole number of the performed flaps were 20. The search confirmed the possibility of formation island flaps from various regions of the trapezius muscle.


[Plastic surgery of the trachea after laryngectomy enabling breathing without a tracheotomy tube].

Plastic operations of trachea which enable to breath without the tracheotomy tube post total laryngectomy were presented by authors. Those operations were performed immediately post laryngectomy or also some time post remove larynx operation. In the first case the suitable "modeled" fold of the skin is made, in the second case the metallic half-loops are implanted. Results authors have received so far are encouraged to use of those methods.


[Concerning the technique of forming a tracheostomy after total laryngectomy].

Many different techniques of the tracheostoma were presented. The rules making of the tracheostoma at Otolaryngological Clinic in Szczecin and the results of it were discussed. The importance of the free--of tube--tracheostoma was emphasized during the rehabilitation of the patient after total laryngectomy.


[Concerning diagnosis and treatment of parotid neoplasms].

This study is a review of 57 patients with tumours in the parotid glands who underwent surgery at the ORL Clinic in Białystok. Malignant tumours constituted 17.5% of all parotid tumours and adenoid cystic carcinoma was the dominant type in this group. Pleomorphic adenomas were the most common benign tumour. The role of fine needle aspiration biopsy in diagnosis of parotid tumours is discussed. Superficial parotidectomy was the predominant form of treatment (47 cases). Total parotidectomy was done in 7 cases. The results of treatment are presented.


[Controlled ENG examinations of patients with lack of induced unidirectional Ny].

19 patients have been checked by the ENG control examination who had demonstrated during first examination lack of evoked Ny in one direction. The control examinations have been conducted from a few months to 4 years after the first ENG examination. Obtained results showed out that lack of evoked Ny in one direction can be persist or can be improved by going into symmetrical directional preponderance, after that in some cases coming to restitution and integrum. It can be explained by the degree of brainstem reticular substance lesion. The obtained results from the study allow to conclude, that lack of evoked Ny in one direction and coming after it the symmetrical directional preponderance have a topo-diagnostic value.


[Complications of tonsillectomy].

The surgical treatment of the tonsils may cause different complications including even death. The author gives the examples of such complications and also pays attention to the importance of being cautious during this intervention.


[The influence of hearing aids on the ability of directional hearing in a free auditory field].

The study was on subject of preservation of directional hearing in free auditory field, in horizontal plane in different stages of pathological lesions of the bearing organ with properly fits hearing aid from Viennatone as the behind-the-ear hearing aid (model 116 PAD) and the hearing spectacles (model 90 AN). There were noticed in 50 percentage of subjects improvement in the directional hearing. The best results was obtained in unilateral deafness. The evidently amelioration was observed in front azimuths. The obtained improvement directional hearing was not proportional to the stage of hearing improvement.


[Vertigo in patients with otosclerosis and post stapedectomy].

The aim of the paper was evaluation of behaviour of the balance system in patients with clinical otospongiosis and after stapedectomy. The investigation was carried out in 131 otosclerotic patients. Before and post operation vertigo was noticed and the spontaneous nystagmus, positional nystagmus and directional preponderance in kinetic test were examined in ENG. Vertigo and objective symptoms of disturbance of the vestibular function were found in clinical otospongiosis, but postoperative subjective and objective symptoms were more frequently.


[Difficulties in diagnosis and treatment of refractory epistaxis].

A case is described of surgically treated refractory epistaxis in a man aged 56 years. The role of angiography in the choice of suitable management was pointed out.


[Cases of granular cell tumor (myoblastoma) in the larynx].

Two patients suffering from very rare granular cell tumor of the larynx were observed at the ENT Department of Medical School in Szczecin in the period 1986 to 1990. In one case the tumor located in the intra-arythenoid region was treated by tyreotomy. In the second case the tumor contained comisura anterior and cricothyreoidea region and was resected by subglottic laryngectomy. The functional results of the treatment were satisfactory.


[Several generations of developmental abnormalities of the branchial arches and cleft].

Morphology and pathological mechanism of congenital anomalies of the first and second branchial arch and cleft were discussed. Present views on heredity of those malformations have been also presented. Five examples of familial occurrence of microtia and cleft are described.


Passive exposure to cocaine in medical personnel and its effect on urine drug screening tests.

This report studies the importance of passive exposure of medical personnel to cocaine hydrochloride and its impact on urine screening testing. Eleven medical staff members were exposed to cocaine hydrochloride by means of aerosol and cutaneous application, similar to that which may occur in medical practice. Urine drug screening tests were negative for everyone tested. This finding is supported by known drug kinetics. It is unlikely that a single passive exposure of medical staff to cocaine hydrochloride will produce a positive urine screening test. In all cases of positive urine tests, contaminants should be tested for which may indicate a source of the drug. The routine use of gloves and masks--which is recommended to prevent HIV infection--should further decrease medical personnel's passive exposure to cocaine hydrochloride.


Indications for open cervical node biopsy in HIV-positive patients.

Open node biopsy was the method of choice for diagnosing human immunodeficiency virus (HIV) infection before serologic testing became available. Currently, the otolaryngologist is often called on to assist in the management of HIV-positive patients with troublesome cervical adenopathy. Today's questions are: what is the place of fine-needle aspiration (FNA), and when is open cervical node biopsy indicated. A retrospective review was undertaken of 93 consecutive cervical node biopsies performed by our department during the 5-year period from 1985 to 1989. Twenty of the patients who underwent biopsy were HIV-positive. Of these twenty, ten carried an established diagnosis of acquired immune deficiency syndrome (AIDS). Seventeen of these patients underwent FNA before biopsy. In the eight patients with persistent generalized lymph-adenopathy (PGL) and nontender, nonenlarging nodes, pathologic analysis revealed lymphoid hyperplasia. Five of these patients had antecedent FNA, none demonstrating any pathologic changes. Of the twelve patients with enlarging or tendon nodes, the diagnosis of mycobacterial adenitis was made in eight, Nocardial infection in two, Burkitt's lymphoma in one, and metastatic Kaposi's sarcoma in one. In four of the patients diagnosed with mycobacterial infections, FNA yielded cytologic evidence of acid-fast bacilli and open lymph node biopsy added nothing. In contrast, FNA failed to reveal the diagnosis in both patients with Nocardial infection, and in the two patients with neoplastic disease. We conclude that cervical node biopsy is not indicated in the HIV or AIDS patient with nontender or nonenlarging nodes.(ABSTRACT TRUNCATED AT 250 WORDS)


Bilateral electrocochleographic findings in unilateral Menière's disease.

At present, electrocochleography is the only proven investigation that can demonstrate objectively the presence of endolymphatic hydrops. The electrophysiologic recordings in response to sound stimuli show an enhancement of the negative summating potential in these cases. It is well established that patients with unilateral Meniere's disease have a high likelihood of development of the disease bilaterally in the fullness of time. Using transtympanic electrocochleography in 40 patients who manifested unilateral clinical Meniere's disease, we have recorded bilateral abnormalities indicative of endolymphatic hydrops in 35% of cases. The early recognition of incipient Meniere's disease in the asymptomatic contralateral ear of a patient with known unilateral disease has obvious profound implications for patient management.


Lipoma of internal auditory canal.

Lipoma of the internal auditory canal is a rare tumor. Clinically, it presents like an acoustic tumor. The diagnosis can be made with the use of a magnetic resonance imaging showing a high intensity on T1- and low intensity on T2-weighted image with no enhancement. Pathologically, this is a soft, smooth, yellow tumor with some fat in it that can resemble grossly any acoustic tumor. The lipoma is intermixed with the eighth nerve and can be adherent to adjacent structures. The growth of a lipoma can be slower than an acoustic tumor. A patient diagnosed with lipoma of the internal auditory canal can often have quite good hearing. As an alternative to surgical removal, another therapeutic option is to watch the growth of the lipoma with periodic magnetic resonance imaging, probably on a yearly basis initially.


Prognostic value of evoked and standard electromyography in acute facial paralysis.

Ninety-one patients with idiopathic (n = 62) and traumatic (n = 29) facial paralyses were available for evaluation at least 1 year after the onset of paralysis. In nine cases of idiopathic paralysis and in 12 cases of traumatic paralysis, total intratemporal nerve decompression was performed. The remaining patients were treated with steroids alone. All patients underwent evoked electromyography (EEMG) testing within 2 weeks of the onset of paralysis. Facial nerve recovery was graded using the House-Brackmann facial nerve recovery scale. Subjects were grouped according to maximal decline of compound muscle action potential (CAP), as determined by EEMG, and by level of recovery 1 year after onset of paralysis. Among patients who did not undergo surgical decompression of the facial nerve, incomplete clinical recovery (grade III or higher) was significantly associated with CAP decline of greater than 90% (p less than 0.05) for idiopathic paralysis. In contrast, there was no significant association between CAP decline of greater than 90% and clinical outcome in traumatic paralysis. These findings support previous reports of the prognostic value of EEMG in idiopathic facial paralysis, but suggest that this test may have less predictive value in the evaluation of facial paralysis as a result of trauma.


Partial endoscopic middle turbinectomy augmenting functional endoscopic sinus surgery.

Endoscopic sinus surgery has gained acceptance in the otolaryngologic community as an effective and safe method of treating inflammatory disease of the paranasal sinuses. At our institution, partial endoscopic middle turbinectomy has become a standard component of the procedure and our experience is reported. Middle turbinectomy enhances surgical exposure, specific anatomic anomalies are more completely corrected, and subpopulations of patients at risk for failure because of their underlying disease enjoy decreased rates of synechiae formation and closure of the middle meatus antrostomy when followed over time. Photodocumentation of the surgical technique and a discussion regarding the impact of middle turbinectomy on normal nasal physiology are presented. It is reported that the procedure is safe, and no complications directly attributable to middle turbinectomy (including atrophic rhinitis) are reported in a series of 298 patients.


Mandibular lingual releasing approach.

The mandibular lingual releasing approach to oral cavity and oropharyngeal tumors provides excellent visualization for resection while integrity of the mandibular arch is preserved. A lingual floor-of-mouth flap is created, which allows delivery of these structures directly into the neck without lip splitting, mandibulotomy, or mandibulectomy. The procedure was carried out on 15 patients between 1987 and 1991, with followup ranging from 2 to 50 months. Nine patients had received previous radiation, whereas planned postoperative radiation was administered to five patients. The visualization afforded by this technique was very good, in that 12 patients had clear margins of resection. Three patients had close margins; recurrent disease developed in one of these patients 18 months later. Twelve of the patients were able to maintain their weight with an oral diet alone. Four postoperative fistulae occurred, three of these were in patients who had not been previously irradiated. The single fistula that did not spontaneously heal occurred in a patient who had received previous radiation and was also on long-term corticosteroids. Mandibular osteoradionecrosis developed in two patients who received postoperative radiation. The complication rate after previous radiation is acceptable; however, there is risk of mandibular osteoradionecrosis after high-dose postoperative radiation.


The canalith repositioning procedure: for treatment of benign paroxysmal positional vertigo.

The Canalith Repositioning Procedure (CRP) is designed to treat benign paroxysmal positional vertigo (BPPV) through induced out-migration of free-moving pathological densities in the endolymph of a semicircular canal, using timed head maneuvers and applied vibration. This article describes the procedure and its rationale, and reports the results in 30 patients who exhibited the classic nystagmus of BPPV with Hallpike maneuvers. CRP obtained timely resolution of the nystagmus and positional vertigo in 100%. Of these, 10% continued to have atypical symptoms, suggesting concomitant pathology; 30% experienced one or more recurrences, but responded well to retreatment with CRP. These results also support an alternative theory that the densities that impart gravity-sensitivity to a semicircular canal in BPPV are free in the canal, rather than attached to the cupula. CRP offers significant advantages over invasive and other noninvasive treatment modalities in current use.


Computer-aided three-dimensional measurement of the human vestibular apparatus.

Using a computer-aided three-dimensional reconstruction and measurement method, 12 measurements were made to determine the dimensions of the maculae, cristae ampullares, and semicircular canals in 18 temporal bones from nine pairs of age-matched male and female individuals (1 day to 76 years old). The surface areas of the utricular and saccular maculae were significantly larger in male than in female specimens (two-way analysis of variance, F = 9.00, df = 1, p less than 0.01; F = 4.57, df = 1, p less than 0.05, respectively). The width of the utricular macula and the length of the saccular macula were also significantly greater in male than in female specimens (two-way analysis of variance, F = 5.17, df = 1, p less than 0.05; F = 4.33, df = 1, p less than 0.05, respectively). Finally, the three semicircular canals were larger in diameter in male vs. female specimens; this difference was statistically significant for the superior semicircular canal (two-way analysis of variance, F = 10.74, df = 1, p less than 0.01). By contrast, none of these dimensions of those vestibular structures showed any significant change in size with advancing postnatal age. We propose from these findings that there appears to be sexual dimorphism in the vestibular apparatus.


Cochlear implants in children: reliability of computed tomography.

Preoperative temporal bone computed tomography (CT) can demonstrate anatomic details relevant to surgical management and is therefore essential in the presurgical evaluation of patients receiving cochlear implants. The purpose of this study was to evaluate preoperative CT studies and compare them to surgical findings in 34 children who received the Nucleus multichannel cochlear implant. The focus of this report is to discuss the dependability of CT scans in predicting surgical findings at the time of cochlear implantation. Results indicate that agreement of CT interpretations with surgical findings is partially related to the etiology of hearing loss and the experience of the surgeon and neuroradiologist. Advantages and limitations of the CT scans in predicting surgical findings are discussed.


Surface sensibility of the floor of the mouth and tongue in healthy controls and in radiated patients.

Increased areas of anesthesia in the oral cavity have been shown to significantly impair oral function in normal individuals. In patients who undergo oral cavity reconstruction, loss of sensation plays a major role in producing disturbances in postoperative oral function. Free tissue transfer techniques have permitted the problem of sensory loss to be addressed through the use of sensate cutaneous free flaps, in which microneural anastomoses are performed between a sensory nerve supplying the flap and a recipient nerve in the head and neck. To critically assess the results of such reconstructions, the effect of sensory restoration on oral cavity rehabilitation must be studied. As a first step toward this goal, normal values for sensory discrimination of the floor of mouth and tongue are needed. Previous studies of oral sensation failed to examine the ventral tongue and floor of mouth. The purpose of this study is to determine the surface sensibility of these regions in healthy patients and in patients who received radiation therapy to the oral cavity. Sensation was evaluated using static and moving two-point discrimination in 90 healthy subjects divided equally into three age groups: 20 to 40 years, 41 to 60 years, and 61 to 80 years. In addition, 20 patients who received radiation therapy were studied. The mucosa of the dorsal and ventral aspects of the lateral tongue, tongue tip, and floor of mouth was examined. The tongue tip is the most sensitive area, followed by the dorsal lateral tongue, ventral lateral tongue, and floor of mouth. The effects of age and radiation therapy on sensory discrimination are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)


Pain after surgery for acoustic neuroma.

Postoperative pain after surgery in the cerebellopontine angle (CPA) is acknowledged to occur, but is rarely taken into account as a factor in the analysis of morbidity of such surgery. It is widely acknowledged that some patients, having undergone such surgery, particularly by means of the suboccipital approach, report significant post-operative pain and headache. This study was undertaken to determine the incidence and severity of pain after excision of acoustic neuromas and to establish whether this differed between the suboccipital and translabyrinthine routes. Ninety-one percent of all patients (n = 58), who had the suboccipital approach used for removal of their tumor, were surveyed. A smaller group (n = 40), matched for tumor size, age, and sex, but in whom the translabyrinthine approach was used, was similarly studied. A standard questionnaire, designed to detect and quantify postoperative pain, was administered to each patient. Of patients who underwent tumor excision by means of the suboccipital approach, 63.7% experienced significant local discomfort and headache, whereas this was notably absent in all those who had undergone translabyrinthine excision. In view of the significant morbidity noted to follow the suboccipital approach, several modifications of the surgical technique used were devised.


Combined infrahyoid and inferior constrictor muscle release for tension-free anastomosis during primary tracheal repair.

Although tracheal stenosis is not a common clinical entity, it still presents a significant management problem, despite recent endoscopic advances. Surgical correction by resection and primary anastomosis is the preferred treatment, provided the repair can be performed without excessive tension. Various release techniques have been described in order to achieve mobility and, thereby, a tension-free anastomosis. This article presents a combined infrahyoid muscle and inferior constrictor muscle release to assure maximum mobility of the laryngotracheal complex, thus allowing tension-free closure. A series of ten patients who underwent primary repair using the combined technique is presented, and the operative technique is described. The indications, age, length of stenosis, and minimum 1 year followup of these patients are presented, as well as perioperative management and complications. The success rate with this technique is 90%.


Community-acquired methicillin-resistant Staphylococcus aureus infections in otolaryngology.

Soon after the introduction of methicillin, strains of Staphylococcus aureus resistant to methicillin were reported. Methicillin-resistant Staphylococcus aureus (MRSA) has become a common hospital pathogen, often resistant to multiple antibiotics, while causing significant morbidity and mortality. Community-acquired MRSA infections have been infrequently documented. Most reports have been associated with intravenous drug abuse. This report reviews 15 patients with community-acquired MRSA infections of the head and neck. None admitted to intravenous drug use. Additionally, no patient was known to be a healthcare worker. The MRSA strains showed antibiotic susceptibility and resistance profiles different from typical hospital-acquired MRSA isolates. All but one infection resolved with adequate surgical or appropriate antibiotic therapy. Clinicians should become aware of the possibility of community-acquired MRSA in the patient who has had continued infection despite antibiotic therapy.


Soft tissue effects of the THC:YAG laser on canine vocal cords.

Recently, a laser based on a thulium-holmium-chromium (THC) doped Yttrium-aluminum-garnet (YAG) rod has been developed that produces light of 2.15 microns wavelength and can be transmitted through a low OH- silica fiberoptic cable. This wavelength falls on one of the peaks of the energy absorption spectrum of water. Thus, the THC:YAG laser eliminates the disadvantage of a cumbersome delivery system found in the CO2 laser while still providing precise cutting and minimal tissue injury inherent in lasers emitting light absorbed by water. We evaluated the soft tissue effects of this laser on canine vocal cords. Ablative lesions were produced by the THC:YAG laser and histologically examined on postoperative days 1, 7, and 28. Results indicate that the depth of tissue penetration is easily controlled and the healing response to tissue injury is comparable to that of the CO2 laser. The THC:YAG laser should prove to be a superior laser for use in otorhinolaryngology, especially when adapted to a flexible endoscope.


The riddle of the uvula.

Since ancient times, the uvula has been a subject of interesting and contradictory observations. On the one hand, it was regarded as having a functional role in speech and in immunology, but on the other hand it was regarded as a potentially hazardous organ, possibly responsible for sudden infant death syndrome. None of these hypotheses, however, has been proved. In a previous study on patients undergoing uvulopalatopharyngoplasty, we suggested that the most important function of the uvula is connected with the muscularis uvula. Its function could be related to drinking while bending over. This previous assumption was that the uvula is a phylogenetic remnant from mammals that drink while bending their neck downward. In the present study, the soft palate of eight different mammals was macroscopically and microscopically studied and compared. Of all animals in the study, a small underdeveloped uvula was found only in two baboons. We found that the human uvula consists of an intermix of serous and seromucous glandular masses, muscular tissue, and large excretory canals. The serous and seromucous glands are absent in the other mammals. Thus, the uvula is a highly sophisticated structure, capable of producing a large quantity of fluid saliva that can be excreted in a short time. Both uvula and speech serve to differentiate human beings from animals. Our conclusion is that the uvula is possibly an accessory organ of speech, and may be another marker of human evolution that differentiates man from other mammals.


Intracordal injection increases glottic closing force in recurrent laryngeal nerve paralysis.

Glottic closing pressure during swallowing was measured in the cat with a catheter pressure transducer to study the effectiveness of intracordal injection in increasing glottic pressure in unilateral recurrent laryngeal nerve paralysis. Swallows were elicited by pouring water into the pharynx while the animal was under light anesthesia with ketamine. Peak pressure of the glottic closure for the control group during deglutition was 68.0 +/- 10.5 mm Hg (mean +/- standard deviation). Peak pressure decreased to 22.0 +/- 3.6 mm Hg just after sectioning of the unilateral recurrent laryngeal nerve, and rose to 39.8 +/- 8.3 mm Hg by silicon injection into the paralyzed vocal fold. In a study of chronic cases 1 month or more after unilateral recurrent laryngeal nerve section, peak pressure was 49.1 +/- 23.4 mm Hg, and varied widely from 21 to 92 mm Hg because of differences in the position of the paralyzed vocal fold and the degree of compensation by the unaffected vocal fold. In the group that had the paralyzed vocal fold fixed in the median position, peak pressure was almost the same as that of the control group. When the paralyzed vocal fold was fixed in either the paramedian or lateral position, peak pressure was 33.3 +/- 7.0 mm Hg. This value was significantly elevated to 45.8 +/- 10.4 mm Hg by injection of silicon, though it remained lower than that of the control. These results suggest that the decrease in glottic closing force during swallowing as a result of unilateral recurrent laryngeal nerve lesion is compensated for by the unaffected vocal fold to some degree and is improved by intracordal injection.


Monitoring impaired physicians: a tool for relapse prevention.

Physicians experience a broad spectrum of health problems which can disrupt their personal lives and impair their ability to function professionally. Some of these illnesses--such as alcoholism and other drug dependency, and certain psychiatric disorders--are chronic. While treatment usually results in remission of active symptoms, there is a risk of relapse if necessary steps are not followed. Therefore, the key to continued recovery and stable functioning lies in effective relapse prevention.


KePRO's community outreach programs.

The Keystone Peer Review Organization board of directors and management have always taken pride in knowing that individually and as a group they have put forth extra effort to assure maximum efficiency and fairness in the review system. Another source of pride to the organization is our Community Outreach Program which we think is one of the finest and most progressive in the country. While such a program is required under our contract with the Health Care Financing Administration (HCFA), we saw the need to go beyond the HCFA requirements.


Medical ethics and maternal-fetal conflicts.

As ethical issues are raised by more and more aspects of medical practice, medical ethics becomes an ever more complex and confusing enterprise, presenting yet another physician dilemma. This article offers guidelines for individual physicians and hospital ethics committees in dealing with medical ethics and maternal-fetal conflicts.


Clarifying concurrent care.

Pennsylvania Blue Shield's concurrent care policy for both the Medicare program and its private business is the source of much confusion and exasperation among physicians, especially with regard to medical-medical concurrent care. This article seeks to clarify the process for better understanding by physicians.


Possible changes in store for PRO program.

Some drastic changes in the peer review organization (PRO) program have been proposed by the Health Care Financing Administration in recent months. Some of them are good, but, as we see them, some could cause problems for PROs, hospitals, and physicians.


Understanding durable powers of attorney.

Many physicians will encounter the use of durable powers of attorney in their medical practices as patients become more informed and more prepared for end-of-life decisions. Be aware, however, that these documents vary in the authority they grant the holder, and that they differ significantly from living wills.


HCFA and the political scene.

Will the fact that this is a presidential election year affect the philosophy and direction of the Health Care Financing Administration as it relates to health care financing in general and the peer review organization program in particular? Perhaps.


A courtroom lesson in physician-assisted suicide.

Physician participation in euthanasia and assisted suicide has been the subject of long-standing debate and is unlikely to be resolved easily or soon. The Pennsylvania Medical Society's Medical Student Section explored this topic recently in a second "mock trial" held in conjunction with the Temple University School of Law and co-sponsored by the Pennsylvania Medical Society Liability Insurance Company. This is an account and essay from that trial.


[Personal memories of personally experienced pediatrics (1946-1991)].

As a kind of farewell speech about my pediatric activity some personal experiences are described, which are of special interest for me and perhaps of a certain historic interest for the reader. The occurrences derives from my profession at the University-Clinics of Pediatrics in Vienna, Bern, Basel and Innsbruck.


[Organization of the psychotherapy-psychosomatic department and its integration into the University Pediatric Clinic].

With regard to the 20 years history of our psychotherapeutic unit some essential feed-back-loops between medical pediatric work and our systemic thinking are presented. So-called objective tasks interfere with group dynamics and subjective task formulations. If two models (the biomedical and the systemic-therapeutic) collide, both of them get "contaminated" and should be changed in a co-evolutive process--for the sake of the patients and their families. In our experience this is only possible, if autonomy of the unit is present, then the unit can wait for "perturbations".


[Bronchial asthma and systematic family therapy: treatment concept, initial contact and therapy follow-up].

Psychosocial factors play an important role in pathogenesis and maintenance of bronchial asthma. However, besides conventional treatment family therapy seems to be less applied. A treatment plan for the integration of systemic family therapy into pediatric management of asthma has been developed and validated. Its special feature is an invariant family treatment offer after the initial session, with the decision of acceptance or rejection upon the family. The main focuses of family therapy are coping and family interaction, thus indirectly influencing the course of illness. Up to now 66 family sessions have been conducted with 11 families; five families agreed to the first session only. In a mean observation time of two years after the end of family therapy we found a drastic reduction in hospital readmissions of the asthmatic patients, even in the patients of families who took part in the initial session only. This may indicate a better control of asthma symptoms in patients and families. Family therapy is suggested as a valuable and additional tool in treatment of asthmatic children, irrespectively of their allergic status.


[The painful hip joint in the child: differential diagnosis and therapy of coxitis fugax, Perthes disease and septic coxitis].

The differential diagnosis of a painful hip joint in children is important. Transient synovitis is frequently seen in children from 3 to 7 years of age with a short history of limping. The joint effusion is visualized by ultrasound. Radiograms and laboratory data are negative. Therapy consists of short term bed rest supported by an oral antiphlogistic drug. Children with Legg-Calve-Perthes disease complain about knee or hip pain in an early stage. X-ray documentation in the a.p and axial view are mandatory as well as ultrasound visualization of the accompanying effusion. Healing of the capital femural epiphysis is aided by weight relief and improved head containment. This may need from one to three years according to the age of the child and the amount of head involvement. More than half of the children's hips with Perthes disease surgical help to achieve a satisfactory result. Hip pain is overwhelming in cases of septic arthritis of the hip joint. This is the most important help to differentiate septic coxitis from transient synovitis or Perthes disease. Rapidly rising values of red cell sedimentation and c-reactive protein are important for early diagnosis. Septic effusions are visualized by ultrasound. X-ray changes are absent in the beginning and are seen only in delayed cases. Early arthrotomy with scrupulous rinsing of the joint, followed by parenteral antibiotic treatment, is the treatment of choice.


Cerebral infarction in a child. A case report.

Cerebral infarcts in children are rather rare and in most cases no precise etiology is established. The authors describe a case of cryptogenetic cerebral infarction in a 9-year-old boy. The child presented an acute onset of hemiplegia in the right arm and leg, central facial palsy, dysarthria and steppage. The infarction was proved by Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). Laboratory and instrumental studies rule out all known causes of brain infarction. The only possible etiopathogenetic hypothesis was a varicella arteritis which occurred 45 days before the clinical manifestation.


[Familial Mediterranean fever--a case report].

A case of a ten years old boy with recurrent fever and abdominal pain starting at the age of five years is reported. Later the attacks were accompanied by chest pain. There were only indifferent changes in laboratory examination. Neither a wide range of antibiotics, nor appendectomy and tonsillectomy prevented the boys symptoms. The diagnose was established after five years by a positive Metaraminol test, that precipitated a disease-like attack. The therapeutic use of colchicine-salicylate reduced the severity and frequency of attacks in out patient. In agreement with other authors it should be emphasized, that in general the benefit of colchicine outweighs possible side effects of a long term therapy also in children.


[Stress and susceptibility to infection].

The influence of various stressors upon the human immune system, was and presently is the subject of many clinically oriented as well as experimental studies. Even though it is not always clear how relevant the reported observations are in behalf to the beginning, the course and the outcome of infectious, neoplastic and autoimmune diseases, there is hardly any doubt, that stress may influence multiple aspects of the immune answer. The sensitivity of the immune system to stress factors is not merely fortuitous, but is an indirect consequence of the regulatory reciprocal influences between the immune system and the central nervous system. These interconnections seem to represent building blocks of a long-loop regulatory feedback-system, which plays an important role in the coordination of stressors and psychological influences upon the course of infections and inflammatory diseases.


[From psychobiological stress research to neuropsychoimmunology].

Psychoimmunology--a neologism--is a short term for the growing evidence that there are multiple interactions between central nervous system, vegetative nervous system, endocrinological system and immunological system. In the history of research the psychobiological stress concept of Hans Selye has been the most powerful basis for the ongoing empirical work in investigating aspects of systemic processes of psychoimmunology. Nowadays there is no doubt that the immunological system must not be seen as an independently functioning organic system. Simple causal links (like stressor-strain-relations) are not useful in explaining the complex interactions that we observe when biological phenomena simultaneously are taken into consideration. Especially with psychological stressors--the most frequent kind of troubles in our contemporary way of life--we have to stress the importance of the individual's evaluation of potentially stressful situations. In a wide variety a stressor becomes the potential of provoking strain because of my own appraisal. This multiple-step-process of appraisal is dependent on my coping abilities and coping strategies regarding an objectively or subjectively dangerous situation. Although there are common genetic and predispositional factors influencing the stress reaction we have to focus more on psychological phenomena, especially the possibility of conditioning stress reactions. As we know by empirical data some reactions of the immunological system are also influenced by learning processes like classical conditioning procedures. This knowledge may be used for a better understanding of a lot of chemical findings.


[Liposomal amphotericin B in the treatment of candida infection in a 3-month-old infant].

Amphotericin B (Amph-B) is the treatment of choice for systemic fungal infections. The application of high doses is limited due to the high incidence of acute side effects (fever, chills) and organ toxicity (reduction in glomerular filtration rate, renal tubular damage). Amph-B was applied without success in a three months old infant, who suffered from systemic candidiasis. After a change to high doses (3-5 mg/kg/day) of liposomal Amph-B (Amph-lip) rapid improvement of the patient's condition occurred and the pulmonary lesions disappeared during six weeks of treatment (total dose 185.5 mg/kg). Acute side effects or renal function abnormalities did not occur. The reported case indicates that the application of high doses of Amph-lip is an alternative to conventional Amph-B in treatment of systemic fungal infections.


Chronic epidural bupivacaine-opioid infusion in intractable cancer pain.

This study examined the efficacy and toxicity associated with chronic epidural opioid-bupivacaine infusions. In a series of 68 patients with cancer pain refractory to epidural opioids alone, analgesia was effectively regained by infusing a opioid-bupivacaine combination. Sixty-one patients (90%) were considered treatment successes, according to conventional criteria. Median length of therapy was 60-120 days, with the longest infusion lasting 277 days. Chronic bupivacaine infusion concentrations ranged from 0.1 to 0.5% with infusion rates varying from 4 to 18 ml/h. The majority of patients experienced pain relief with little or no sympathetic or sensorimotor impairment after the first 24 h at bupivacaine concentrations of 0.125-0.25% and were managed in home or chronic care settings without the need for re-hospitalization. In patients receiving higher bupivacaine concentrations, sympathetic, sensory and motor blockade were well tolerated during chronic infusion. Sensory loss was consistently observed only at bupivacaine concentrations exceeding 0.25%, and motor impairment occurred only at concentrations exceeding 0.35%. Postural hypotension was observed in 6 patients (9%) for the first 24 h only, which supports the requirement for monitoring and fluid therapy during initiation of the bupivacaine infusion. No patient experienced CNS or systemic toxicity, despite plasma total bupivacaine concentrations as high as 10.8 micrograms/ml. Serial plasma bupivacaine levels were measured in 15 patients during chronic infusion. There was considerable inter- and intra-individual variability in plasma bupivacaine concentrations and bupivacaine clearance. We conclude that epidural opioid-bupivacaine infusion is an effective and safe technique for long-term administration of analgesics in the refractory cancer patient.


Patient-controlled analgesic infusions: alfentanil versus morphine.

Previously, we found that cancer patients using a pharmacokinetically based patient-controlled intravenous infusion system (PKPCA) to regulate their own morphine infusion rates achieved more relief from oral mucositis pain than similar patients using morphine by bolus-dose PCA. In this study, we employed the PKPCA system to compare efficacy and side-effect intensities of 2 mu-selective opioid analgesics, alfentanil and morphine, in bone marrow transplant (BMT) patients self-administering the drugs to relieve pain from oral mucositis. Patients using morphine by PKPCA obtained more pain relief than patients regulating their own alfentanil infusions during the first 4 days of continuous opioid infusion therapy. Side-effect intensities did not differ between the 2 study groups. In contrast to patients using morphine for 4-14 days, those receiving alfentanil by PKPCA required unexpectedly high plasma concentrations of the drug to obtain equivalent pain relief. Our results indicate that either the relative potencies of these 2 mu-selective opioids differ from previous estimates or analgesic tolerance developed to alfentanil but not to morphine. We conclude that alfentanil has similar efficacy in control of prolonged pain in BMT patients, but the utility of alfentanil in long-term pain management may be limited by relatively rapid tolerance onset.


Circadian distribution of extra doses of narcotic analgesics in patients with cancer pain: a preliminary report.

In this open study we reviewed the circadian distribution of extra doses of narcotic analgesics in 61 bed-ridden patients with cancer pain. The information was collected prospectively and retrospectively in 34 and 27 cases, respectively. All patients were receiving parenteral narcotics using the Edmonton Injector, and none had incidental pain or cognitive impairment. A total of 1322 extra doses of narcotics (each dose = 10% of the daily dose) were administered during 610 patient days (average of 2.17 +/- 1.6 doses/patient/day). The mean daily number of extra doses during each interval was as follows: 02.00-06.00 h (0.24 +/- 0.27), 06.00-10.00 h (0.26 +/- 0.31), 10.00-14.00 h (0.43 +/- 0.44), 14.00-18.00 h (0.44 +/- 0.41), 18.00-22.00 h (0.40 +/- 0.36), and 22.00-02.00 h (0.40 +/- 0.36) (02.00-06.00 h and 06.00-10.00 h vs. 10.00-02.00 h: P less than 0.01). Forty-five of 61 patients (76%) received most of their extra doses of narcotics between 10.00 and 22.00 h. The data suggest that our patients require a larger number of extra doses during day time. Our design cannot establish the reason for this circadian variation.


Cervicogenic headache: anesthetic blockades of cervical nerves (C2-C5) and facet joint (C2/C3).

In a series of 14 patients with cervicogenic headache, cervical nerve blockades (C2-C5 and facet joint C2/C3) have been carried out in order to elucidate possible underlying mechanisms and to evaluate the diagnostic potential of these procedures. Blockade of the C2 nerve resulted in freedom from pain in 5 of 10 patients and seemed to be the most informative procedure. Two patients out of 9 reported freedom from pain following C2/C3 facet joint injection. No patients experienced complete pain relief following C3, C4 or C5 blockades. C4 and C5 nerve blockades are probably of little value in the work-up of such patients. When evaluating the C2/C3 facet joint injection, one has to take possible leakage of anesthetic agent from the joint into consideration, since the third occipital nerve which runs close to the facet joint may be anesthetized through the leakage.


The efficacy and efficiency of a self-administered treatment for adolescent migraine.

Migraine headaches are frequent in adolescents. Although many adolescents are adequately treated palliatively with analgesics, an important subgroup requires prophylactic treatment. Medical treatments for adolescents with frequent severe headaches is often problematic. Prophylactic pharmacological treatments are often shunned by adolescents and their parents because of concern over drug usage. Moreover, propranolol, the most widely used prophylactic drug with adults, is frequently not effective. Psychological interventions are effective but are costly and often not available. A randomized controlled trial was undertaken to evaluate the efficacy and efficiency of a predominantly self-administered treatment that could be delivered in a very cost-efficient format. Eighty seven adolescents (63 females and 24 males) ranging in age from 11 to 18 years were randomly assigned to receive a self-administered treatment, the same treatment delivered by a therapist or a control treatment. Self-administered and clinic treatment were equally effective and superior to the control treatment. However, the self-administered treatment was substantially more efficient. Both active treatments were durable at 1-year follow-up.


Facet joint injection and facet nerve block: a randomised comparison in 86 patients with chronic low back pain.

Eighty-six patients with refractory chronic low back pain were randomly assigned to receive either facet joint injection or facet nerve block, using local anaesthetic and steroid. There was no significant difference in the immediate response. The duration of response after facet joint injection was marginally longer than after facet nerve block (P less than 0.05 1 month after infiltration), but for both groups the response was usually short-lived; by 3 months only 2 patients continued to report complete pain relief. Patients who had complained of pain for more than 7 years were more likely to report good or excellent pain relief than those with a shorter history (P less than 0.005), but no other clinical feature was of value in predicting the response to infiltration. Facet joint injections and facet nerve blocks may be of equal value as diagnostic tests, but neither is a satisfactory treatment for chronic back pain.


The effectiveness of psychological interventions for the rehabilitation of low back pain: a randomized controlled trial evaluation.

Forty-five low back pain patients were randomly assigned to either a standard inpatient rehabilitation program or the standard program with additional psychological components. The standard program emphasized education, support, and physical reconditioning through exercise. Patients receiving the psychological program were given additional training in relaxation and other coping skills and received contingent reinforcement for exercise. Both programs included reduction of medication intake and an emphasis on family involvement after discharge. Measures of functional status were taken prior to the program, at discharge from the 3-week inpatient program, and at a 6-month follow-up appointment. These data revealed that patients improved their overall functioning at discharge and maintained these gains at the follow-up assessment. A similar pattern of findings was obtained for self-reported pain and interference. Furthermore, 81% of the patients had returned to work or were engaged in active job retraining by the follow-up. Using a conservative measure of full-time return to the same or an equivalent job, 57% were employed by the follow-up. Patient improvement, however, was not differentially affected by treatment group assignment, suggesting that the psychological treatment failed to add to the effectiveness obtained by the standard rehabilitation program. Results are discussed in the context of improving patient outcomes from rehabilitation for low back pain.


Psychological aspects of reflex sympathetic dystrophy: a review of the adult and paediatric literature.

In 1864, W. Mitchell and colleagues first described the clinical syndrome which came to be known as 'causalgia'. Since that time, the concept of sympathetically related pain has evolved. There is general agreement that profound emotional and behavioural changes can follow these types of pain. Opinions have varied widely on the issue of a psychological etiology. It has often been suggested that certain personality traits predispose one to develop sympathetically related pain syndromes. A review of the literature reveals no valid evidence to substantiate this claim.


The effect of experimental muscle pain on the background electrical brain activity.

The purpose of this project was to investigate whether specific effects in the background activity of the brain associated with the experience of pain can be depicted by means of quantitative electroencephalography (EEG). Lasting pain was induced by intramuscular infusion of hypertonic saline. The infusion was titrated to maintain pain for a sufficient time to obtain enough data for meaningful analysis. In a first study on 12 subjects, using a single, blind, repeated measures design with randomization of the administration of isotonic (0.9%) and hypertonic (5%) saline, and with subjects unaware of the fact that one substance was isotonic saline, a statistically significant pain response could be attributed to the administration of hypertonic saline. In a second study on 19 subjects, again using a randomized repeated measures design, topographic EEG measures were examined with respect to experimentally induced pain and pain from memory. Prior to each of these experimental stages, baseline recordings were obtained to satisfy the requirement of the crossover design. In addition to the common frequency bands used in EEG, we also obtained data in the frequency range of 35-100 Hz. The short-term variability of the selected EEG measures and their suitability as a sample estimate were assessed by computing the coefficient of variation from all selected epochs of a given subject at baseline. When compared to baseline, spectral analyzed EEG measures during experimental pain demonstrated statistically significant increases in the beta and 35-100 Hz frequency ranges, most notably at the temporal recording sites. There was no statistically significant difference between the EEG measures for (1) experimental pain vs. pain from memory, and (2) the 2 baseline recordings. The great variability in the topographical aspect of the between-subject response was interpreted as being strongly suggestive of the contamination of EEG measures by phenomena attributed to the jaw, facial and scalp musculature. In fact, Pearson correlation coefficients, as high as 0.92, were found between measures in the frequency band of 35-100 Hz and the beta frequency range. The unexplained variance in the heightened beta cortical power density can be attributed to the vigilance scanning of pain processes. Due to the fact that the statistically significant effect of pain on the topographic EEG measures were not different from imagined pain, we concluded that these effects are non-specific for pain.


Cerebrospinal fluid kinetics of epidural clonidine in man.

Ten patients with deafferentation pain after spinal cord injury were given 150 micrograms clonidine epidurally. CSF and plasma samples were collected over the following 24 h, and drug concentrations were measured by radio-immunoassay. The results of only 6 patients are included in the pharmacokinetic analysis because the catheters were not in the epidural space in the remaining 4 patients. These analyses revealed a mean maximum CSF concentration of 228 ng/ml whereas the mean plasma concentration at all time points was less than 0.7 ng/ml. The elimination half-life of epidural clonidine was 66 +/- 2 min, while the absorption half-life was 31 +/- 7 min, Tmax was 60 +/- 7 min and Cmax was 228 +/- 56 ng/ml. The ratio of the area under the curve (AUC) for CSF and plasma was 52. One patient's catheter was intrathecal and 3 were not in the epidural space. The measured plasma concentrations were similar after all injections. As 4 of 6 patients with epidural catheters obtained pain relief and all 3 patients with spasms obtained relief from epidural clonidine, these data suggest that clonidine has a place in the treatment of patients with spinal cord injury.


CT contrast evidence of injectate encapsulation after long-term epidural administration.

This case report provides radiographic evidence (CT scan with Iopamidol) to support the development of epidural injectate encapsulation in response to long-term epidural morphine injections via an implanted polyurethane catheter. The patient complained of intense low interscapular pain when the catheter was used for administration of epidural morphine for control of angina. The patient had previously enjoyed 3 months of excellent pain relief following the initiation of epidural morphine via an implanted portal device. The CT scan, with contrast dye injected via the epidural catheter, clearly showed loculation of the injectate and associated indentation of the spinal cord. It is significant to note that the dye in the encapsulated sheath occupied a significant proportion of the spinal canal extending from T7 to T9.


Viscerosomatic convergence onto feline spinal neurons from esophagus, heart and somatic fields: effects of inflammation.

One objective of this study was to examine a mechanism for the inability of patients to distinguish esophageal pain from cardiac pain. Patients with esophageal disease and angina pectoris often perceive pain as originating from the same somatic fields. Another objective was to compare the effect of esophageal distension between animals with a non-inflamed or with an inflamed esophagus. For this study in anesthetized cats, we recorded extracellular action potentials from T2-T7 spinal neurons that responded to intraluminal distension of an untreated or a turpentine-inflamed distal esophagus. Threshold distension volumes were compared between these 2 groups of animals. Neurons also were examined for effects of intracardiac bradykinin injection and somatic stimuli. Results showed that spinal neurons responded to a smaller threshold distension volume when cells in animals with an inflamed distal esophagus were compared to cells in animals with a non-inflamed distal esophagus. Spinal neurons that received input from the distal esophagus also received convergent input from the heart and somatic fields. Our data supported the hypotheses that (1) referred pain from the distal esophagus resulted from activation of the same spinal neurons by visceral and somatic input, (2) pain originating from the distal esophagus and heart might be difficult to distinguish because of viscerosomatic and viscerovisceral convergence onto the same spinal neurons, and (3) an inflamed distal esophagus might be more sensitive to distension than a non-inflamed esophagus.


Fos-like proteins in the lumbosacral spinal cord following noxious and non-noxious colorectal distention in the rat.

The rat lumbosacral spinal cord was immunocytochemically stained for Fos-like immunoreactivity following repetitive colorectal distention (CRD) to 20, 40 or 80 mm Hg. Following all 3 distention pressures, Fos-like immunoreactive (Fos-ir) nuclei were observed primarily in laminae I-II, V-VII and X, although some labeled nuclei were observed in laminae III-IV. Eighty mm Hg CRD resulted in significantly more Fos-ir nuclei than 20 or 40 mm Hg CRD. Morphological examination of the colon revealed clear signs of inflammation following 80 but not 20 mm Hg CRD. Acute 20 mm Hg CRD is a non-noxious stimulus, suggesting that both noxious and non-noxious visceral stimuli can induce Fos-like immunoreactivity in the spinal cord. It is suggested that activation of neuropeptide-containing small-diameter primary afferents is necessary, although not necessarily sufficient, to induce c-fos in the rat spinal cord.


Differential influence of naloxone on the responses of nociceptive neurons in the superficial versus the deeper dorsal horn of the medulla in the rat.

Naloxone (200 micrograms/kg, i.v.) reduced the noxious thermal stimuli-evoked responses of 16/25 nociceptive neurons in the superficial laminae whereas it enhanced the responses of 6/10 nociceptive neurons in the deeper dorsal horn. However, a different picture emerged when selectivity of neuronal responsivity (nocireceptive or multireceptive) was considered. In the superficial dorsal horn, naloxone reduced the responses of the majority of (15/18) selectively nocireceptive neurons. The reduction in responses became apparent within 60 sec following naloxone administration and returned to control level within 48 min. In contrast, the responses of the majority of multireceptive neurons in the superficial (6/7), or the deeper (6/10) dorsal horn, were enhanced. The excitatory action in the superficial dorsal horn persisted for only 6-15 min, whereas it persisted for 40-70 min in the deeper dorsal horn. The firing of the majority of cold-receptive neurons (6/8) in the superficial dorsal horn was not altered. These effects were stereoselective since (+)-naloxone, the inactive isomer of naloxone, did not affect the responses of 14/16 nociceptive neurons. It is concluded that naloxone differentially, and selectively, affects the firing of nociceptive neurons in the superficial versus the deeper dorsal horn, and the firing of selectively nocireceptive versus multireceptive neurons. The relevance of these findings to the behavioral effects of naloxone, hyperalgesia and analgesia, is discussed.


Differential antinociceptive effects of morphine and methylmorphine in the formalin test.

The antinociceptive activities of morphine, and its quaternary analogue methylmorphine, have been compared after intraperitoneal and intracerebroventricular administrations in the mouse paw formalin test. Systemic morphine inhibited both the early and late phases of the formalin-induced licking response and this activity was naloxone sensitive. In contrast, systemic methylmorphine inhibited only the late phase, and this activity was blocked by pre-treatment with methylnaloxone. Central administration of either morphine or methylmorphine inhibited the early phase of the licking response partially and the late phase completely. Systemic naloxone inhibited the central action of both opioids, whilst systemic methylnaloxone did not affect the central action of methylmorphine. The results indicate that the early phase of the response to formalin in the mouse may be inhibited by stimulation of central opioid receptors whilst inhibition of the late phase may involve both peripheral and central opioid receptors.