Acute hydrocephalus after subarachnoid hemorrhage.

This issue of Stroke includes an important discussion of acute hydrocephalus after subarachnoid hemorrhage (SAH), contributed by a group of investigators from The Netherlands who have made several important recent contributions to our understanding of the pathophysiology of SAH. The data of Hasan et al, derived from a careful study of 473 consecutive patients with SAH admitted within 72 hours after ictus, are interesting in several respects. They show that hydrocephalus, defined as a bicaudate index on computed tomogram (CT scan) exceeding the 95th percentile for age, occurs in approximately 20% of patients, which is in agreement with previous studies in which similar criteria were used.They also show that in approximately a third of these patients hydrocephalus is asymptomatic. More important, half of the patients with initial hydrocephalus and impairment of consciousness improve spontaneously within 24 hours. This finding confirms a previous report from the same group as well as another larger report from England but is in contrast to an earlier study by another group in which only one of nine patients with symptomatic acute hydrocephalus improved spontaneously. An incidental finding of some interest is that Hasan et al found that hydrocephalus was just as frequent in their series of 46 patients who had negative angiograms and hence no identified etiology for their SAH. However, only one of these 46 patients was symptomatic, and there were no episodes of rebleeding or delayed ischemia, which confirms the generally held belief that such patients run a benign clinical course. Improvement in consciousness after ventricular drainage occurred in 78% of the 32 patients treated by either external drainage (24 patients) or by an internal shunt (eight patients). This is in agreement with one report in which 18 of 21 such patients improved rapidly and another report in which such improvement occurred in seven of 11 patients. The disappointing aspect of the data of Hasan et al, however, is that ventriculitis developed in 50%