Hydrocephalus

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Skull of a newborn

Hydrocephalus

Definition:

Hydrocephalus is an accumulation of cerebrospinal fluid in the ventricles of the brain, leading to their enlargement and swelling.

Alternative Names:
Water on the brain
Causes, incidence, and risk factors:

Cerebrospinal fluid (CSF) is formed in a region of the brain known as the choroid plexus. CSF usually circulates through channels of the brain known as ventricles, as well as flowing around the outside of the brain and through the spinal canal.

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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.

The symptoms vary depending on the cause of the obstruction, the person's age when the problem develops, and the extent of brain tissue damage caused by the swelling.

In infants, fluid accumulates in the central nervous system, causing the fontanelle (soft spot) to bulge and the head to expand. An infant's head can enlarge because the bony plates that 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, hydrocephalus may be associated with infections acquired before birth, injury occurring during the birth process, congenital defects, tumors of the central nervous system, infections that affect the central nervous system (such as meningitis or encephalitis ), and 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 a history of congenital or developmental defects, space-occupying lesions or tumors of the brain or spinal cord, central nervous system infections, bleeding anywhere in the brain, and trauma.

Hydrocephalus most often occurs in children, but may also occur in adults and the elderly.

See normal pressure hydrocephalus (NPH).