The diagnosis and treatment of idiopathic normal pressure hydrocephalus.

Idiopathic normal pressure hydrocephalus (INPH) is a syndrome that is characterized by gait impairment, cognitive decline and urinary incontinence, and is associated with ventriculomegaly in the absence of elevated cerebrospinal fluid (CSF) pressure. There is significant variation in the clinical presentation and progression of this disorder, and its diagnosis often represents a challenge for neurologists and neurosurgeons. Various supplemental tests, including the CSF tap test, external CSF drainage via spinal catheter, and CSF outflow resistance determination, can improve the accuracy of predicting a response to surgical treatment. CSF shunting provides significant symptom improvement in the majority of appropriately evaluated patients. In 2005, an international study group published evidence-based guidelines for the diagnosis and management of INPH. This review will highlight the clinical presentation, radiographic findings, supplemental prognostic tests, differential diagnosis, surgical treatment and outcomes of INPH.