The impact of microsurgical fenestration of the lamina terminalis on shunt-dependent hydrocephalus and vasospasm after aneurysmal subarachnoid hemorrhage.

Objective: Chronic hydrocephalus requiring shunt placement and cerebral vasospasm are common complications after aneurysmal subarachnoid hemorrhage. Recent publications have investigated the possibility that microsurgical fenestration of the lamina terminalis during aneurysm surgery may reduce the incidence of shunt-dependent hydrocephalus and cerebral vasospasm. We reviewed a single-surgeon series to compare postsurgical outcomes of patients who underwent fenestration of the lamina terminalis against those who did not.

Methods: This study is a retrospective review of the medical records of 369 consecutive patients with aneurysmal subarachnoid hemorrhage admitted to Columbia University Medical Center between January 2000 and July 2006. All patients underwent craniotomy and clipping of at least one ruptured cerebral aneurysm by a single neurosurgeon (ESC). The incidences of shunt-dependent hydrocephalus, conversion from acute hydrocephalus on admission to chronic hydrocephalus, and clinical cerebral vasospasm were compared in patients who underwent fenestration of the lamina terminalis with those who did not. The patient cohort was thus divided into three subgroups: 1) patients whose operative records clearly indicated that they underwent fenestration of the lamina terminalis, 2) patients whose operative records clearly indicated that they did not undergo fenestration of the lamina terminalis, and 3) patients whose operative records did not indicate one way or another whether they received fenestration of the lamina terminalis. We performed two separate analyses by comparing the postsurgical outcomes in those patients who were fenestrated versus those who were definitively not fenestrated and comparing the postsurgical outcomes in those patients who were fenestrated versus those who were not plus those whose records did not document fenestration. To further control for any cohort differences, we performed a comparison between patients who were fenestrated and those who were not after matching 1:1 for presenting radiographic and clinical characteristics predictive of hydrocephalus and vasospasm. Outcomes were compared using logistic regression and multivariable analysis.

Results: In the first model, fenestrated patients had a shunt rate, conversion rate, and rate of clinical vasospasm of 25, 50, and 23%, respectively, versus 20, 27, and 27% in nonfenestrated patients, respectively (P = 0.28, 0.21, and 0.32, respectively). In the second model, the nonfenestrated patients plus nondocumented patients had a shunt rate, conversion rate, and rate of clinical vasospasm of 16, 40, and 20%, respectively (P = 0.19, 0.33, and 0.60, respectively). In the matched cohort, fenestrated patients had a shunt rate, conversion rate, and rate of clinical vasospasm of 29, 67, and 20%, respectively, versus 20, 25, and 25% in nonfenestrated patients, respectively (P = 0.30, 0.24, and 0.20, respectively).

Conclusion: In contrast to other retrospective multisurgeon series, our retrospective single-surgeon series suggests that microsurgical fenestration of the lamina terminalis may not reduce the incidence of shunt-dependent hydrocephalus or cerebral vasospasm after aneurysmal subarachnoid hemorrhage. A prospective multicenter trial is needed to definitively address the use of this maneuver.