NPH was first described in 1965. The classic triad of dementia, gait problems, and urinary incontinence associated with hydrocephalus in the presence of normal brain pressure (<20 mm Hg) was reported (1).
It has been estimated that 0.5% of the population over the age of 55 have NPH of the idiopathic form (iNPH). In the U.S., there are approximately 375,000 people with this disorder. The exact cause of the hydrocephalus is unknown. Some postulate that problems with Cerebrospinal Fluid (CSF) Absorption lead to dilation of the cerebral ventricles. Others propose that the cerebral degeneration that occurs with age leads to gradual loss of brain tissue (encephalomalacia) and subsequent expansion of the ventricles (2). There is an increased incidence of NPH in those with a history of traumatic brain injury, brain tumor, or stroke.
The best treatment for NPH is surgical placement of a shunt. This is generally a ventriculo-peritoneal shunt. The results vary and can range from the spectacular to very slight or mild improvement. Proper selection of patients prior to surgery allows for the best possible outcomes. There are newer imaging modalities that help to identify those patients that are more likely to improve with the surgery.
Improved surgical techniques and new shunt technology has decreased the risks of surgery. This is particularly important as many of the patients with NPH are elderly and have many other health issues.