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hydrocephalus (hi″dro-sef´ә-lәs) enlargement of the skull because of abnormal accumulation of cerebrospinal fluid within the ventricular system of the brain. Although it occurs occasionally in adults, it is usually seen in young children associated with a congenital defect, especially a neural tube defect. The two common types of hydrocephalus are communicating and noncommunicating, distinguished according to whether there is or is not obstruction to the outflow of cerebrospinal fluid. adj., hydrocephal´ic., adj. communicating hydrocephalus
hydrocephalus caused by some abnormality in the capacity to absorb fluid from the arachnoid space, with no obstruction to
flow of fluid between the ventricles. Infections, hemorrhage into the ventricles of the brain (a common problem in premature
infants), trauma, and tumors can produce this. noncommunicating hydrocephalus
hydrocephalus due to an obstruction somewhere in the ventricular system of the brain, usually a congenital abnormality such
as severe narrowing of the aqueduct of Sylvius, congenital blockage or absence of the foramina of the fourth ventricle, or spina bifida cystica. normal-pressure hydrocephalus
, normal-pressure occult hydrocephalus
dementia, ataxia, and urinary incontinence with hydrocephalus, i.e., with enlarged ventricles associated with inadequacy of
the subarachnoid spaces, occurring in middle-aged and older persons. The cerebrospinal and spinal fluid pressures are at the
upper end of normal, but with the excess spinal fluid volume, that pressure is actually abnormally high. Called also occult
normal-pressure hydrocephalus.
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