To Shunt or Not to Shunt Patients with Idiopathic Normal Pressure Hydrocephalus? A Reappraisal of an Old Question

The possibility that the cerebral ventricles can dilate without any increase in the pressure of the cerebrospinal fluid (CSF) was recognized in 1935 by Penfield who reported a patient in whom "…the cerebrospinal fluid spaces are closed and the ventricles progressively enlarge without the measured intraventricular pressure rising above 150 to 200 mm of water"