Only a proportion of patients with aSAH-associated acute hydrocephalus develop shunt-dependent chronic hydrocephalus. The method of deter- mining which patients require ventricular shunt placement was studied in a single-center, prospective, randomized, controlled trial in which 41 patients were randomized to rapid weaning of EVD (wean period 24 hours) and 40 patients were randomized to gradual EVD weaning (wean period 96 hours).245 There was no difference in the rate of shunt placement (63.4% rapid versus 62.5% gradual), but the gradual wean group had 2.8 more days in the intensive care unit (P 0.0002) and 2.4 more days in the A number of retrospective series have attempted to identify factors predictive of aSAH-associated shunt-dependent nonrandomized studies236,258 261 with 1718 pooled patients (1336 who underwent clipping, 382 who underwent coiling) found a lower risk of shunt dependency in the clipping group (relative risk, 0.74; 95% confidence interval, 0.58 0.94) than in the coiling group (P 0.01); however, only 1 of the 5 studies showed an independent significant difference.258 Three other nonrandomized series not included in the meta- analysis showed no significant difference between clipping and coiling in shunt-dependent chronic hydrocepha- lus.237,244,262 Fenestration of the lamina terminalis has been suggested to reduce the incidence of shunt-dependent chronic hydrocephalus, yet a meta-analysis243 of 11 nonrandomized studies234,260,263 271 pooled 1973 patients (975 who had un- dergone fenestration and 998 who had not) and found no significant difference in shunt-dependent hydrocephalus be- tween patients who had undergone fenestration of the lamina terminalis and those who had not (10% in the fenestrated cohort versus 14% in the nonfenestrated cohort; P 0.09). 