Background: Acute hydrocephalus is a potentially treatable cause of ea
rly neurological deterioration after aneurysmal mal subarachnoid hemor
rhage (SAH). Methods: A retrospective study of 105 consecutive cases o
f aneurysmal SAH was undertaken to determine those factors significant
ly related to the development of acute hydrocephalus. Acute hydrocepha
lus was diagnosed when the bicaudate index was greater than the 95(th)
percentile for age on a CT scan within 72 hours of the ictus, Results
: Thirty-one percent of the patients developed acute hydrocephalus. Gr
ade of SAH was a significant factor for the development of acute hydro
cephalus on univariate analysis as 87% of patients with acute hydrocep
halus (29/32) presented with at least grade 3 (Hunt-Hess) SAH (p < 0.0
5). In addition, posterior circulation aneurysms on univariate analysi
s were associated with acute hydrocephalus (p < 0.05). Both premorbid
hypertension and intraventricular blood (p < 0.05) were predictors for
acute hydrocephalus, whereas intracisternal blood, age and sex were n
ot. On multivariate linear regression analysis, factors found to be si
gnificantly associated with acute hydrocephalus were premorbid hyperte
nsion, intraventricular blood, CSF diversion and definitive shunt proc
edures. External ventricular drainage was not associated with any inst
ances of rebleeding. Thirty-seven percent (10/27) of patients with acu
te hydrocephalus who survived were improved by pre-operative external
ventricular drainage. Conclusions: Patients with acute hydrocephalus f
ollowing SAH can be safely treated with external ventricular drainage.
Multiple factors can be identified to predict those patients who will
develop acute hydrocephalus post aneurysmal rupture. Approximately 30
% of those patients with acute hydrocephalus will require definitive s
hunt placement. Acute hydrocephalus occurred in 31% of aneurysmal SAH
patients in this series.