CT showing early ventricular dilatation after subarachnoidal hemorrhage

We performed a retrospective analysis of 398 patients with subarachnoidal hemorrhage (SAH) confirmed by CT. On the first CT examination the temporal horns were enlarged in 84%, the frontal horns in 32%, and the third ventricle in 21% of the patients. The amount of blood in the basal cisterns was highly correlated to dilatation of the temporal horns. The temporal horns were enlarged even when small amounts of blood were found in the cisterns. The frontal and temporal horns were dilated only when moderate or large amounts of blood were present in the cisterns. In 24 patients no blood was seen in the basal cisterns on CT performed within 5 days of the hemorrhage; none of the 3 patients with aneurysms showed normal temporal horns while 18 without demonstrable aneurysms had normal, and 3 had moderately dilated, temporal horns. Because the temporal horns cannot usually be seen at CT of healthy individuals, dilatation could be a useful sign in the diagnosis of SAH.