Normal pressure hydrocephalus.

Idiopathic normal pressure hydrocephalus (INPH) is a treatable neurological disorder in older adults involving disturbances of gait/balance, control of micturition, and/or cognition in combination with enlargement of the cerebral ventricles. Diagnosis can be challenging due to its varied presentation and overlap with other disorders common in the elderly. Evidence-based consensus guidelines for diagnosis and treatment of INPH have been created that can assist in clinical management. Diagnosis requires clinical documentation of one or more of the characteristic symptoms of INPH in combination with a brain imaging study demonstrating nonobstructive ventricular enlargement disproportionate to cerebral atrophy. Gait and balance disturbances are the most common presenting findings in INPH and may occur alone or together with cognitive and urinary symptoms. Adjunct tests, particularly those involving transient removal of cerebrospinal fluid via lumbar puncture or lumbar drain, can serve the dual purpose of adding to diagnostic certainty and assisting in prognostication about response to treatment. Prognostication is important because neurosurgical treatment by placement of a ventricular shunt, while effective, carries the risk of potentially significant morbidity. Outcome of shunting in INPH is most often successful when patients are accurately diagnosed, suitably evaluated for surgical candidacy, and managed carefully throughout the preoperative, surgical, and postoperative periods.