The effects of fenestration of the interpeduncular cistern membrane arousted to the opening of lamina terminalis in patients with ruptured ACoA aneurysms: a prospective, comparative study

Background. The incidence of chronic hydrocephalus requiring shunt placement is a well-known and common complication of aneurysmal subarachnoid hemorrhage (aSAH). It was suggested that fenestration of the lamina terminalis (LT) during microsurgery for aSAH may be associated with a reduced rate of shunt-dependent chronic hydrocephalus (SDCH). We analyzed that, fenestrations of the LT and Liliequist membrane (LM) would reduce rate of SDCH and improve rate of favorable outcome. Methods. 145 patients who were analyzed in the study were treated in our department with ruptured anterior communicating artery (ACoA) aneurysms. We compared the rate of shunting and clinical outcome in patients in whom only fenestration of the LT (Group 1) was performed with that in patients in whom fenestrations of both the LT and LM (Group 2) were performed. Results. Chronic hydrocephalus requiring shunting amounted to 9.8% (7 patients) in Group 1 and 4% (3 patients) in Group 2 (p = 0.203). Also, there were no differences in the rate of shunt dependent hydrocephalus between the two groups in patients with Fisher's CT grades 3 (p = 0.343) and 4 (p = 0.667), and HH grades 4 (p = 0.306) and 5 (p = 0.361). Favorable clinical outcomes were observed with rates of 74.6% in Group 1 and 79.7% in Group 2 (p = 0.693). Also there were no differences in the rates of favorable clinical outcome between the two groups in patients with Fisher's CT grades 3-4, HH grades 4-5. Conclusions. Our study shows that fenestration of the LM coupled with the opening of the LT reduced-relatively-the incidence of SDCH; this however was not significant. This positive effect was particularly noticeable in patients in whom a cisternal "overflow" was observed at surgery when opening the LM. This corresponded to cases with ventricular dilatation and a IVth ventricle with clots.