PROSPECTIVE ANALYSIS BY COMPUTED-TOMOGRAPHY AND LONG-TERM OUTCOME OF 23 ADULT PATIENTS WITH CHRONIC IDIOPATHIC HYDROCEPHALUS

FROM 1986 TO 1989, 23 adult patients (average age, 70 yr) with idiopat hic chronic hydrocephalus received shunts with medium-pressure Pudenz- Schulte valves for suspected normal pressure hydrocephalus. Prospectiv e clinical and computed tomographic monitoring was continued for at le ast 5 years. We observed the formation of a hypodense subdural collect ion in each of 10 patients (43%). Those collections that occurred earl y, i.e., within the first 9 postoperative days, evolved differently fr om those that occurred late; only early hypodense collections became s ubdural hematomas (three cases). In one case, a subdural hematoma was already present 9 days after surgery, so that four patients (17%) pres ented a subdural hematoma within the first 2 postoperative months. Our long-term follow-up revealed three patients (13%) with hypodense subd ural collections, which appeared more than 2 months after surgery. Non e of the collections evolved into a subdural hematoma. Thirteen patien ts (57%) died between 9 and 68 months (average, 20 mo) after surgery, most often of an ischemic stroke. During the 1st postoperative year, t here was improvement in the condition of 22 patients (96%) who had rec eived a ventricular shunt; 21 of these patients (91%) remained improve d until death or for at least 5 years.