Factors influencing shunt dependency after aneurysmal subarachnoid haemorrhage.

In this retrospective analysis of 138 patients treated for ruptured aneurysms the development of shunt dependent hydrocephalus was evaluated regarding possible predictive factors. In 15 patients (11%) ventriculo-atrial shunt was implanted due to hydrocephalus. One predictive factor was the localisation of aneurysms as patients with hydrocephalus had PcoA aneurysms in 40% compared to 20% in the group of patients without hydrocephalus and only 7% compared to 28% MCA aneurysms. An other predictive factor was the severity of the subarachnoid haemorrhage (SAH) as 7 patients out of the 15 were graded Fisher IV on admission. Furthermore, an important predictive factor was the presence of acute hydrocephalus as 13 out of the 15 patients (87%) with shunt dependent hydrocephalus had acute hydrocephalus requiring external ventricular drainage. An other possible factor was the intraoperative opening of the lamina terminalis as in 73% of the patients with shunt dependent hydrocephalus compared to 82% in the group of patients without hydrocephalus this procedure was performed during surgery. The results suggest that shunt dependency is more likely after severe SAH especially in the presence of an acute hydrocephalus and in patients with aneurysms located in the basal cisterns. Therefore treatment of the acute hydrocephalus and possible the opening of the lamina terminalis could have a positive effect on the development of shunt dependent hydrocephalus after SAH.