Definition of Normal pressure hydrocephalus

Normal pressure hydrocephalus: A specific form of hydrocephalus in which the central cavities of the inner brain (the ventricles) enlarge at the expense of the substance of the brain, while the pressure of the CSF remains within normal range. Normal pressure hydrocephalus (NPH) is due usually to a gradual blockage of the drainage pathways for cerebrospinal fluid (CSF) in the brain. NPH can occur as a complication of brain infection or hemorrhage. In some patients no predisposing cause can be identified.

NPH is characterized by gradual loss of memory loss (dementia), balance disorder (ataxia), incontinence of urine and a general slowing of activity. Symptoms progressively worsen over weeks. "I became incontinent," one NPH patient recalled. "I went from a cane to a walker to a wheelchair. I lost cognizance, concentration and focus. My intellect was failing," she continued. "I lived in a veiled landscape."

In some patients, an improvement of symptoms is noted immediately after removal of some spinal fluid with a lumbar puncture. Treatment of NPH involves the insertion of a shunt to let the excess fluid exit and relieve the pressure on the brain. The shunt is a flexible, plastic tube with a oneway valve. The shunt is inserted into the ventricular system of the brain to divert the flow of CSF into another area of the body, where the CSF can drain and be absorbed into the bloodstream.

The word "hydrocephalus" in Greek literally means "watery head."