Hydrocephalus

Hydrocephalus

Definition

A condition affiliated with excessive fluid in the brain.

Causes, incidence, and risk factors

The fluid in the brain (cerebrospinal fluid or CSF) is formed in the brain. CSF usually circulates through parts of the brain, its covering, and the spinal canal, and is then absorbed into the circulatory system.

When the circulation or absorption of this fluid is blocked, or excessive fluid is produced, the volume of fluid in the brain becomes higher than normal. The accumulation of fluid puts pressure on the brain forcing it against the skull and damaging or destroying the tissues.

Symptoms vary depending on the cause of the obstruction to CSF circulation, the age at which the problem develops, and the extent of damage to brain tissue caused by the hydrocephalus.

In infants, fluid accumulates in the central nervous system, causing the fontanelle (soft spot) to bulge and the head to expand. The head can enlarge because the bony plates which make up the skull have not yet fused together. However, once the skull bones are completely fused together, at about age 5, the skull will no longer expand.

In small children, risks for developing hydrocephalus include congenital defects, tumors of the central nervous system, intrauterine infection, infections in an infant or child that affect the central nervous system (such as meningitis or encephalitis), injury occurring during the birth process, or trauma before or after birth (including subarachnoid hemorrhage). Myelomeningocele, a disorder involving incomplete closure of the spinal column, is strongly associated with hydrocephalus.

In older children, risks include history of congenital or developmental defects, space-occupying lesions or tumors of the brain...

... middle of paper ...

..., or similar problems)

* infection

* meningitis

* encephalitis

* infection of the area to which CSF is shunted

* intellectual impairment

* neurologic damage (decrease in movement, sensation, function)

* physical disabilities

* complications of surgery

Expectations (prognosis)

Untreated hydrocephalus has a 50 to 60% death rate, with the survivors having varying degrees of intellectual, physical, and neurologic disabilities.

Prognosis for treated hydrocephalus varies depending on the cause. If the child survives for one year, over 80% will have a fairly normal life span. Approximately one-third will have normal intellectual function, but neurologic difficulties may persist.

Hydrocephalus that is caused by disorders not associated with infection carries the best prognosis (probable outcome), although hydrocephalus caused by tumors has a very poor prognosis.