Introduction: Cisternal lavage of subarachnoid blood from ventricular to cisternal spaces forms the basis of advocating ventriculocisternostomy as an adjunct procedure to aneurysm clipping. Moreover, it has theoretical implications for the administration of therapies into the cisternal space to prevent vasospasm. It is therefore crucial to verify that a dynamic flow of CSF does exist from the third ventricle into the chiasmatic cisterns after surgical fenestration of the lamina terminalis (FLT). Here we prospectively studied the patency of anterior third ventriculostomy after FLT during aneurysm surgery through CT cisternography.
Methods: Prospective analysis of 10 patients undergoing clipping of ruptured anterior circulation aneurysms followed by FLT during surgery. Flow of contrast into basal cisterns was assessed with CT imaging obtained 3-5 minutes following 1cc of intraventricular contrast injection (Omnipaque 300, containing 300mg organic iodine/mL), EVD closure and cranial maneuvering designed to position contrast adjacent to the lamina terminalis. Flow of contrast was documented by measuring Hounsfield Units in a pre-specified “region of interest” within the basal cisterns on the CT scan. This procedure was done using a standardized protocol designed in consultation with the Department of Radiology and approved by the institutional IRB.
Results: Ten patients consented to study participation. There was no evidence of contrast appearance within the basal cisterns on post-operative day one ventriculo-cisternograms. In all 10 subjects, contrast followed normal ventricular pathway from the lateral ventricles into the fourth ventricle.
Conclusions: Despite microsurgical FLT after aneurysm clipping, there was no radiological evidence of CSF flow into basilar cisterns one day following creation of a cisternostomy. Reports of beneficial effects of FLT in preventing vasospasm and shunt dependent hydrocephalus following aneurysmal subarachnoid hemorrhage should be taken with caution. Aggressive clot removal and manipulation of Circle of Willis vessels during surgery may instead be responsible for the observed beneficial effects.
Patient Care: Based on this study, routine opening of lamina terminals appears to be an un-necessary and potentially harmful maneuver and does not achieve the physiological goal of improving cisternal flow.
Learning Objectives: By the conclusion of this sessions, participants should be able to: 1) Describe the role of microsurgical fenestration of lamina terminalis after ruptured aneurysm clipping, 2) Describe the need to demonstrate the scientific validity of ventriculo-cisternostomy currently advocated as a necessary adjunct to clipping following aneurysmal subarachnoid hemorrhage