Hydrocephalus pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun M.D., PhD.,Kalsang Dolma, MBBS
Overview
Pathophysiology
Hydrocephalus is usually due to blockage of cerebral spinal fluid (CSF) outflow in the brain ventricles or in thesubarachnoid space over the brain. In a normal healthy person, CSF continuously circulates through the brain and its ventricles and the spinal cord and is continuously drained away into the circulatory system. In a hydrocephalic situation, the fluid accumulates in the ventricles, and the skull may become enlarged because of the great volume of fluid pressing against the brain and skull. Alternatively, the condition may result from an overproduction of the CSF fluid, from a congenital malformation blocking normal drainage of the fluid, or from complications of head injuries or infections.[1]
Infants and young children with hydrocephalus typically have abnormally large heads, because the pressure of the fluid causes the individual skull bones which have not knitted with each other yet to bulge outward at their juncture points. Compression of the brain by the accumulating fluid eventually may cause convulsions and mental retardation. The elevated intracranial pressure may cause compression of the brain, leading to brain damage and other complications. Conditions among affected individual vary widely. Children who have had hydrocephalus may have very small ventricles.
If the foramina (pl.) of the fourth ventricle or the cerebral aqueduct are blocked, cereobrospinal fluid (CSF) can accumulate within the ventricles. This condition is called internal hydrocephalus and it results in increased CSF pressure. The production of CSF continues, even when the passages that normally allow it to exit the brain are blocked. Consequently, fluid builds inside the brain causing pressure that compresses the nervous tissue and dilates the ventricles. Compression of the nervous tissue usually results in irreversible brain damage. If the skull bones are not completely ossified when the hydrocephalus occurs, the pressure may also severely enlarge the head. The cerebral aqueduct may be blocked at the time ofbirth or may become blocked later in life because of a tumor growing in the brainstem.
Usually, hydrocephalus need not cause any intellectual impairment if recognized and properly treated. A massive degree of hydrocephalus rarely exists in normally functioning people, and such rarity may occur if onset is gradual rather than sudden.[2]
References
- ↑ "Hydrocephalus Fact Sheet", National Institute of Neurological Disorders and Stroke. (August 2005).
- ↑ "Man with tiny brain shocks doctors", New Scientist (2007-07-20).