hydrocephalus hydrocephalus hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (csf) occurs within the brain. this typically causes increased pressure inside the skull. older people may have headaches, double vision, poor balance, urinary incontinence, personality changes, or mental impairment. in babies, it may be seen as a rapid increase in head size. other symptoms may include vomiting, sleepiness, seizures, and downward pointing of the eyes. not to be confused with hypocephalus or hydranencephaly. hydrocephalusother nameswater on the brainhydrocephalus as seen on a ct scan of the brain. the black areas in the middle of the brain (the lateral ventricles) are abnormally large and filled with fluid.pronunciation/ˌhaɪdroʊˈsɛfələs/ specialtyneurosurgerysymptomsbabies: rapid head growth, vomiting, sleepiness, seizuresolder people: headaches, double vision, poor balance, urinary incontinence, personality changes, mental impairmentcausesneural tube defects, meningitis, brain tumors, traumatic brain injury, brain bleed during birth, intraventricular hemorrhagediagnostic methodbased on symptoms and medical imagingtreatmentsurgeryprognosisvariable, often normal lifefrequencyvaries throughout the world, from 1 per 256 live births to 1 per 9,000, depending on access to prenatal health care, prenatal tests, and abortion hydrocephalus can occur due to birth defects or be acquired later in life. associated birth defects include neural tube defects and those that result in aqueductal stenosis. other causes include meningitis, brain tumors, traumatic brain injury, intraventricular hemorrhage, and subarachnoid hemorrhage. the four types of hydrocephalus are communicating, noncommunicating, ex vacuo, and normal pressure. diagnosis is typically made by physical examination and medical imaging. hydrocephalus is typically treated by the surgical placement of a shunt system. a procedure called a third ventriculostomy is an option in some people. complications from shunts may include overdrainage, underdrainage, mechanical failure, infection, or obstruction. this may require replacement. outcomes are variable, but many people with shunts live normal lives. without treatment, death or permanent disability may occur. about one to two per 1,000 newborns have hydrocephalus. rates in the developing world may be higher. normal pressure hydrocephalus is estimated to affect about 5 per 100,000 people, with rates increasing with age. description of hydrocephalus by hippocrates dates back more than 2,000 years. the word hydrocephalus is from the greek ὕδωρ, hydōr, meaning 'water' and κεφαλή, kephalē, meaning 'head'. signs and symptoms illustration showing different effects of hydrocephalus on the brain and cranium adult showing cranial deformity from pediatric hydrocephalus the clinical presentation of hydrocephalus varies with chronicity. acute dilatation of the ventricular system is more likely to manifest with the nonspecific signs and symptoms of increased intracranial pressure (icp). by contrast, chronic dilatation (especially in the elderly population) may have a more insidious onset presenting, for instance, with hakim's triad (adams' triad). symptoms of increased icp may include headaches, vomiting, nausea, papilledema, sleepiness, or coma. with increased levels of csf, there have been cases of hearing loss due to csf creating pressure on the auditory pathways or disrupting the communication of inner ear fluid. elevated icp of different etiologies have been linked to sensorineural hearing loss (snhl). transient snhl has been reported after the loss of csf with shunt surgeries. hearing loss is a rare but well-known sequela of procedures resulting in csf loss. elevated icp may result in uncal or tonsillar herniation, with resulting life-threatening brain stem compression. hakim's triad of gait instability, urinary incontinence, and dementia is a relatively typical manifestation of the distinct entity normal-pressure hydrocephalus. focal neurological deficits may also occur, such as abducens nerve palsy and vertical gaze palsy (parinaud syndrome due to compression of the quadrigeminal plate, where the neural centers coordinating the conjugated vertical eye movement are located). the symptoms depend on the cause of the blockage, the person's age, and how much brain tissue has been damaged by the swelling. in infants with hydrocephalus, csf builds up in the central nervous system (cns), causing the fontanelle (soft spot) to bulge and the head to be larger than expected. early symptoms may also include: eyes that appear to gaze downward irritability seizures separated sutures sleepiness vomiting symptoms that may occur in older children can include: brief, shrill, high-pitched cry changes in personality, memory, or the ability to reason or think changes in facial appearance and eye spacing (craniofacial disproportion) crossed eyes or uncontrolled eye movements difficulty feeding excessive sleepiness headaches irritability, poor temper control loss of bladder control (urinary incontinence) loss of coordination and trouble walking muscle spasticity (spasm) slow growth (child 0–5 years) delayed milestones failure to thrive slow or restricted movement vomiting because hydrocephalus can injure the brain, thought and behavior may be adversely affected. learning disabilities, including short-term memory loss, are common among those with hydrocephalus, who tend to score better on verbal iq than on performance iq, which is thought to reflect the distribution of nerve damage to the brain. hydrocephalus that is present from birth can cause long-term complications with speech and language. children can have issues such as nonverbal learning disorder, difficulty understanding complex and abstract concepts, difficulty retrieving stored information, and spatial/perceptual disorders. children with hydrocephalus are often known in having the difficulty in understanding the concepts within conversation and tend to use words they know or have heard. however, the severity of hydrocephalus can differ considerably between individuals, and some are of average or above-average intelligence. someone with hydrocephalus may have coordination and visual problems, or clumsiness. they may reach puberty earlier than the average child (this is called precocious puberty). about one in four develops epilepsy. cause congenital a one-year-old girl with hydrocephalus showing "sunset eyes", before shunt surgery congenital hydrocephalus is present in the infant prior to birth, meaning the fetus developed hydrocephalus in utero during fetal development. the most common cause of congenital hydrocephalus is aqueductal stenosis, which occurs when the narrow passage between the third and fourth ventricles in the brain is blocked or too narrow to allow sufficient cerebral spinal fluid to drain. fluid accumulates in the upper ventricles, causing hydrocephalus. other causes of congenital hydrocephalus include neural-tube defects, arachnoid cysts, dandy–walker syndrome, and arnold–chiari malformation. the cranial bones fuse by the end of the third year of life. for head enlargement to occur, hydrocephalus must occur before then. the causes are usually genetic, but can also be acquired and usually occur within the first few months of life, which include intraventricular matrix hemorrhages in premature infants, infections, type ii arnold-chiari malformation, aqueduct atresia and stenosis, and dandy-walker malformation. hydrocephalus has also been seen in cases of congenital syphilis. in newborns and toddlers with hydrocephalus, the head circumference is enlarged rapidly and soon surpasses the 97th percentile. since the skull bones have not yet firmly joined, bulging, firm anterior and posterior fontanelles may be present even when the person is in an upright position. the infant exhibits fretfulness, poor feeding, and frequent vomiting. as the hydrocephalus progresses, torpor sets in, and infants show lack of interest in their surroundings. later on, their upper eyelids become retracted and their eyes are turned downwards ("sunset eyes") (due to hydrocephalic pressure on the mesencephalic tegmentum and paralysis of upward gaze). movements become weak and the arms may become tremulous. papilledema is absent, but vision may be reduced. the head becomes so enlarged that they eventually may be bedridden. about 80–90% of fetuses or newborn infants with spina bifida—often associated with meningocele or myelomeningocele—develop hydrocephalus. acquired this condition is acquired as a consequence of cns infections, meningitis, brain tumors, head trauma, toxoplasmosis, or intracranial hemorrhage (subarachnoid or intraparenchymal), and is usually painful. type the cause of hydrocephalus is not known with certainty and is probably multifactorial. it may be caused by impaired csf flow, reabsorption, or excessive csf production. obstruction to csf flow hinders its free passage through the ventricular system and subarachnoid space (e.g., stenosis of the cerebral aqueduct or obstruction of the interventricular foramina secondary to tumors, hemorrhages, infections or congenital malformations) and can cause increases in icp. hydrocephalus can also be caused by overproduction of csf (relative obstruction) (e.g., choroid plexus papilloma, villous hypertrophy). bilateral ureteric obstruction is a rare, but reported, cause of hydrocephalus. hydrocephalus can be classified into communicating and noncommunicating (obstructive). both forms can be either congenital or acquired. communicating communicating hydrocephalus, also known as nonobstructive hydrocephalus, is caused by impaired csf reabsorption in the absence of any obstruction of csf flow between the ventricles and subarachnoid space. this may be due to functional impairment of the arachnoidal granulations (also called arachnoid granulations or pacchioni's granulations), which are located along the superior sagittal sinus, and is the site of csf reabsorption back into the venous system. various neurologic conditions may result in communicating hydrocephalus, including subarachnoid/intraventricular hemorrhage, meningitis, and congenital absence of arachnoid villi. scarring and fibrosis of the subarachnoid space following infectious, inflammatory, or hemorrhagic events can also prevent reabsorption of csf, causing diffuse ventricular dilatation. noncommunicating noncommunicating hydrocephalus, or obstructive hydrocephalus, is caused by an obstruction to the flow of csf. foramen of monro obstruction may lead to dilation of one, or if large enough (e.g., in colloid cyst), both lateral ventricles. the aqueduct of sylvius, normally narrow, may be obstructed by a number of genetic or acquired lesions (e.g., atresia, ependymitis, hemorrhage, or tumor) and lead to dilation of both lateral ventricles, as well as the third ventricle. fourth ventricle obstruction leads to dilatation of the aqueduct, as well as the lateral and third ventricles (e.g., chiari malformation). the foramina of luschka and foramen of magendie may be obstructed due to congenital malformation (e.g., dandy–walker malformation). other hydrocephalus ex vacuo from vascular dementia as seen on mri normal pressure hydrocephalus (nph) is a particular form of chronic communicating hydrocephalus, characterized by enlarged cerebral ventricles, with only intermittently elevated cerebrospinal fluid pressure. characteristic triad of symptoms are; dementia, apraxic gait and urinary incontinence. the diagnosis of nph can be established only with the help of continuous intraventricular pressure recordings (over 24 hours or even longer), since more often than not instant measurements yield normal pressure values. dynamic compliance studies may be also helpful. altered compliance (elasticity) of the ventricular walls, as well as increased viscosity of the cerebrospinal fluid, may play a role in the pathogenesis. hydrocephalus ex vacuo also refers to an enlargement of cerebral ventricles and subarachnoid spaces, and is usually due to brain atrophy (as it occurs in dementias), post-traumatic brain injuries, and even in some psychiatric disorders, such as schizophrenia. as opposed to hydrocephalus, this is a compensatory enlargement of the csf-spaces in response to brain parenchyma loss; it is not the result of increased csf pressure. mechanism spontaneous intracerebral and intraventricular hemorrhage with hydrocephalus shown on ct scan 3d cast of lateral ventricles in hydrocephalus hydrocephalus is usually due to blockage of csf outflow in the ventricles or in the subarachnoid space over the brain. in a person without hydrocephalus, csf continuously circulates through the brain, its ventricles and the spinal cord and is continuously drained away into the circulatory system. alternatively, the condition may result from an overproduction of the csf, from a congenital malformation blocking normal drainage of the fluid, or from complications of head injuries or infections. compression of the brain by the accumulating fluid eventually may cause neurological symptoms such as convulsions, intellectual disability, and epileptic seizures. these signs occur sooner in adults, whose skulls are no longer able to expand to accommodate the increasing fluid volume within. fetuses, infants, and young children with hydrocephalus typically have an abnormally large head, excluding the face, because the pressure of the fluid causes the individual skull bones—which have yet to fuse—to bulge outward at their juncture points. another medical sign, in infants, is a characteristic fixed downward gaze with whites of the eyes showing above the iris, as though the infant were trying to examine its own lower eyelids. the elevated icp may cause compression of the brain, leading to brain damage and other complications. a complication often overlooked is the possibility of hearing loss due to icp. the mechanism of icp on hearing loss is presumed that the transmission of csf pressure to and from the perilymphatic space through a patent cochlear aqueduct. the cochlear aqueduct connects the perilymphatic space of the inner ear with the subarachnoid space of the posterior cranial fossa. a loss of csf pressure can induce perilymphatic loss or endolymphatic hydrops resembling the clinical presentation of ménière's disease associated hearing loss in the low frequencies. csf can accumulate within the ventricles,