What is the medical term for an accumulation of cerebrospinal fluid in the brain?

The medical term for an accumulation of cerebrospinal fluid in or around the brain is hydrocephalus. The excess fluid can enlarge the brain’s ventricles and, in some cases, raise pressure inside the skull.

Cerebrospinal fluid, or CSF, normally circulates through the brain’s ventricles and around the spinal cord. It cushions the central nervous system, carries nutrients, and helps remove waste. Hydrocephalus develops when CSF flow is blocked, reabsorption is impaired, or—much more rarely—production is excessive. Aqueductal stenosis, bleeding, tumors, infections such as meningitis, and congenital brain abnormalities can all disrupt this balance.

The condition does not look the same at every age. In infants, whose skull bones have not fully fused, pressure may cause rapid head enlargement. Older children and adults may develop headaches, nausea, vision problems, balance difficulties, drowsiness, or cognitive changes. Normal-pressure hydrocephalus is a distinctive form in older adults associated with walking difficulty, urinary problems, and impaired thinking. Cerebral edema is swelling of brain tissue, not a buildup of CSF, while meningitis and encephalitis are inflammatory diseases.