it was initially developed for angiography , but it has also been found useful in oral and maxillofacial radiology ( omfr ) . the introduction of cbct has made three - dimensional imaging possible in omfr .
cbct offers a 3d approach to data acquisition , image reconstruction , image display , and image interpretation .
cbct scan can be achieved in a relatively short period of time , making it ideal for imaging children and claustrophobic adults .
the patient finds the examination comfortable as it can be performed with the patient in a standing or sitting position .
the technique is characterized by fast image acquisition with relatively high three - dimensional resolution , lower radiation exposure to patients , and fewer artifacts when compared with conventional computed tomography ( ct ) .
the voxels are isotropic and the resolution varies from 0.07 to 0.25 mm depending on the manufacturer .
these values exceed most high - grade multi - slice ct units in terms of spatial resolution , real time image analysis , and three - dimensional display .
cbct technology has been used for preoperative implant planning , evaluation of the jaws , and presurgical assessment of the bone volume required for orthognathic surgery . as
cbct systems have become more prevalent , its use has gained attention in the field of otolaryngology .
cbct of the inner ear [ figures 1 and 2 ] is effective in the diagnoses of most malformations , dysplasia , traumatic lesions , thin osseous labyrinthine wall erosion , or dehiscence .
the advantages and diagnostic value of cbct have been demonstrated in the analysis of the position of cochlear implants in the temporal bone , the free visualization of alloplastic middle ear titanium , gold , or platinum implants .
it is also possible that the smallest bone structure or position of the prosthesis can be defined with high precision contributing valuable information to the diagnosis , preoperative planning , and prevention of intra - operative complications .
60-year - old female patient with clinical history of hearing loss diagnosed with sensorineural hearing loss .
cbct of temporal bone three - dimensional image with air cavity volume rendering ( green ) , shows normal inner ear : semicircular canals ( white arrows ) , vestibule ( white star ) , cochlea ( yellow arrow ) and internal auditory canal ( red star ) .
28-year - old male patient with clinical history of bilateral hearing loss and semicircular canal dehiscence diagnosed with conductive hearing loss due to bilateral fixing of the malleus .
bilateral cbct of temporal bone three - dimensional image with osseous volume rendering demonstrates normal superior semicircular canal .
a semicircular canal dehiscence ( scd ) is characterized by a pathological opening in a small section of the bony wall of the semicircular canal ( sc ) of the inner ear .
an scd can be found in three different places according to different etiologies : the superior [ figures 3 and 4 ] , lateral , and posterior scs .
regardless of differences in scd location , dehiscence patients have complained of similar symptoms such as vertigo , oscillopsia , and/or hearing loss .
35-year - old male patient with clinical history of vertigo and autophony diagnosed with left superior semicircular canal dehiscence .
cbct of temporal bone ( a and d ) coronal ( b ) sagittal ( c ) oblique sagittal images show a dehiscence of the left superior semicircular canal ( white arrow ) .
17-year - old patient with clinic history of progressive hearing loss , without vertigo and oscillopsia diagnosed with sensorineural hearing loss and right superior semicircular canal dehiscence .
cbct of temporal bone , air cavity volume rendering ( green ) images ( a ) sagittal view , ( b ) endocranial view , ( c ) osseous volume rendering oblique sagittal view and ( d ) osseous volume rendering superior view show superior semicircular canal dehiscence ( yellow arrow in a ) , ( yellow arrow in b ) , ( white arrow in c ) , and ( white arrow in d ) .
superior semicircular canal dehiscence ( sscd ) syndrome is characterized by sound and/or pressure - induced vertigo and oscillopsia due to a dehiscence of bone overlying the superior sc in the roof of the temporal bone or in the neighborhood of the epidural space .
minor et al . , first described this in 1998 , and it has become a new and exciting concept in the field of otology .
vertigo as a result of loud noises ( tullio phenomenon ) , autophony , oscillopsia , disequilibrium due to sound changes in middle ear pressure , or changes in intracranial pressure were observed in these patients .
sscd may present with a variety of atypical vestibular and/or auditory symptoms , which can be suggestive of otosclerosis .
sscd is relatively rare , the reported cases in the literature range from 0.4% to 0.7% with the majority of patients being asymptomatic .
several etiologies have been linked to hereditary , developmental , intracranial hypertension , and trauma .
other authors have suggested that sscd may be due to a congenital or a genetic condition .
sscd most commonly occurs along the apex or the roof of the sc , termed the arcuate eminente .
however , approximately 9.1% of sscd may also occur more posteriorly or medially , involving the groove of the superior petrosal sinus [ figure 5 ] .
42-year - old male patient , with clinical history of cranial trauma and initial diagnosis of left temporal bone fracture diagnosed with left temporal bone fracture and ipsilateral superior semicircular canal dehiscence .
cbct of temporal bone shows incidental find of dehiscence of the superior semicircular canal ( black arrow ) in superior petrosal sinus canal area ( white arrow ) , cochlea ( white star ) , and ossicle chain ( black star ) .
diagnosis of sscd is based on the presence of vestibular or auditory symptoms and radiologic findings .
the dehiscence is confirmed with high resolution computed tomography ( hrct ) scanning of the temporal bones using bone window settings .
this is a key component in the diagnosis of sscd , especially when a surgical intervention is contemplated .
minor reported a sensitivity of 100% , a specificity of 99% , a positive predictive value of 99% , and a negative predictive value of 100% in the identification of sscd .
a semicircular canal dehiscence ( scd ) is characterized by a pathological opening in a small section of the bony wall of the semicircular canal ( sc ) of the inner ear .
an scd can be found in three different places according to different etiologies : the superior [ figures 3 and 4 ] , lateral , and posterior scs .
regardless of differences in scd location , dehiscence patients have complained of similar symptoms such as vertigo , oscillopsia , and/or hearing loss .
35-year - old male patient with clinical history of vertigo and autophony diagnosed with left superior semicircular canal dehiscence .
cbct of temporal bone ( a and d ) coronal ( b ) sagittal ( c ) oblique sagittal images show a dehiscence of the left superior semicircular canal ( white arrow ) .
17-year - old patient with clinic history of progressive hearing loss , without vertigo and oscillopsia diagnosed with sensorineural hearing loss and right superior semicircular canal dehiscence .
cbct of temporal bone , air cavity volume rendering ( green ) images ( a ) sagittal view , ( b ) endocranial view , ( c ) osseous volume rendering oblique sagittal view and ( d ) osseous volume rendering superior view show superior semicircular canal dehiscence ( yellow arrow in a ) , ( yellow arrow in b ) , ( white arrow in c ) , and ( white arrow in d ) .
superior semicircular canal dehiscence ( sscd ) syndrome is characterized by sound and/or pressure - induced vertigo and oscillopsia due to a dehiscence of bone overlying the superior sc in the roof of the temporal bone or in the neighborhood of the epidural space .
minor et al . , first described this in 1998 , and it has become a new and exciting concept in the field of otology .
vertigo as a result of loud noises ( tullio phenomenon ) , autophony , oscillopsia , disequilibrium due to sound changes in middle ear pressure , or changes in intracranial pressure were observed in these patients .
sscd may present with a variety of atypical vestibular and/or auditory symptoms , which can be suggestive of otosclerosis .
sscd is relatively rare , the reported cases in the literature range from 0.4% to 0.7% with the majority of patients being asymptomatic .
several etiologies have been linked to hereditary , developmental , intracranial hypertension , and trauma .
other authors have suggested that sscd may be due to a congenital or a genetic condition .
sscd most commonly occurs along the apex or the roof of the sc , termed the arcuate eminente .
however , approximately 9.1% of sscd may also occur more posteriorly or medially , involving the groove of the superior petrosal sinus [ figure 5 ] .
42-year - old male patient , with clinical history of cranial trauma and initial diagnosis of left temporal bone fracture diagnosed with left temporal bone fracture and ipsilateral superior semicircular canal dehiscence .
cbct of temporal bone shows incidental find of dehiscence of the superior semicircular canal ( black arrow ) in superior petrosal sinus canal area ( white arrow ) , cochlea ( white star ) , and ossicle chain ( black star ) .
diagnosis of sscd is based on the presence of vestibular or auditory symptoms and radiologic findings .
the dehiscence is confirmed with high resolution computed tomography ( hrct ) scanning of the temporal bones using bone window settings .
this is a key component in the diagnosis of sscd , especially when a surgical intervention is contemplated .
minor reported a sensitivity of 100% , a specificity of 99% , a positive predictive value of 99% , and a negative predictive value of 100% in the identification of sscd .
teymoortash et al . , analyzed radiological imaging of 43 structures of the temporal bone by cbct and ct in 38 human temporal bones .
the frequency of visualization of these anatomic structures were studied and statistically analyzed : 9 structures ( 20.1% ) of axial scans and 5 structures ( 11.6% ) of coronal scans could be identified as statistically significantly ( p < 0.05 ) more often in cbct than in ct .
they determined that anatomical structures of the temporal bone can be identified significantly better in cbct than in ct scans .
a dehiscent - appearing superior canal was seen in 4.0% of cases , while published pathologic studies reported that only 0.5% of temporal bone sscs have a dehiscence ( p < 0.001 ) .
they established that the prevalence of dehiscent - appearing superior canal on thin - section temporal bone scanning with reformation in the ssc plane is much higher than anticipated by pathologic studies .
the results were compared with intra - operative findings to evaluate the diagnostic value of cbct in cases of erosion of the scs .
they determined the presence of a fistula of the scs in 100% of the cases .
in conclusion , when compared with multi detector computed tomography , cbct imaging for the inner ear is an excellent alternative .
it results in lower radiation to patients , fewer artifacts , and equal or higher resolution depending on the unit used .
 superior semicircular canal dehiscence is a relatively new syndrome in the field of otology . 
 it is of unknown etiology presenting with a variety of vestibular and auditory symptoms and radiologic findings play a crucial role in its diagnosis . 
 cone beam computed tomography has been shown to be a powerful tool in the field of otolaryngology . 
 it is a three dimensional technique that uses lower radiation resulting in fewer artifacts and offers higher resolution when compared with multi - slice computed tomography . 
 it is considered to be an excellent imaging modality for radiological exploration of the ear . 
INTRODUCTION
Superior semicircular canal dehiscence
DISCUSSION
CONCLUSION