Idiopathic normal, pressure hydrocephalus: A systematic review of diagnosis and outcome

OBJECTIVE: Patient selection for cerebrospinal fluid diversion is difficult , because idiopathic normal pressure hydrocephalus (INPH) mimics other neur odegenerative disorders and no findings reliably predict outcome. The liter ature was reviewed to identify diagnostic criteria that predict shunt respo nse and to formulate prognostic expectations. METHODS: MEDLINE was searched, and 44 articles meeting predetermined criter ia were included. RESULTS: Clinical series were frequently retrospective with small patient n umbers and unstandardized outcome evaluation. Clinical findings suggestive of shunt responsiveness were the complete triad (gait disturbance, urinary incontinence, and dementia) with early gait disturbance. Degree of hydrocep halus was not correlated with clinical improvement. Reduction of the subcor tical low-blood flow area was correlated with improvement in three small st udies. Clinical response to prolonged cerebrospinal fluid drainage predicte d shunt outcome in all cases in two small series. Overall, 59% (range, 24-1 00%) of patients improved after shunting, and 29% (range, 10-100%) of patie nts experienced prolonged improvement. Complications occurred in 38% (range , 5-100%) of patients, additional surgery was required in 22% (range, 0-47% ) of patients, and there was a 6% (range, 0-35%) combined rate of permanent neurological deficit and death. CONCLUSION: Shunting INPH is associated with an approximately 29% rate of s ignificant improvement and a 6% significant complication rate. Enlargement of the subcortical low-flow area and clinical improvement secondary to prol onged lumbar drainage may provide additive predictive value above clinical and computed tomographic criteria. A multicenter clinical trial that focuse s on the value of ancillary tests, defines the clinical course of a patient with a ventriculoperitoneal shunt, and evaluates the cost effectiveness of shunting INPH is needed to better describe outcome from shunting in INPH.