Modified Tentorium Incision in the Extended Subtemporal Transtentorial Approach for Posterior Circulation Aneurysms: Technical Note and Clinical Experience

Introduction: Although most posterior circulation aneurysms are currently treated by endovascular means, some may not be amenable to this modality. Among the surgical routes, the subtemporal approach provides excellent exposure of the incisural space. Retraction or incision of the tentorial edge is essential for exposure of the interpeduncular cistern and basilar artery. We present a modified technique of tentorial incision and report our clinical experience with this technique.

Methods: Retrospective review of patients operated on from 01/1999 to 09/2011 via an extended subtemporal transtentorial approach for posterior circulation aneurysms. The modified tentorial incision implies dissection of the trochlear nerve (TN) along its dural canal to its entrance into the cavernous sinus, allowing reflection of the tentorial flap anterolaterally, capitalizing rostrocaudal exposure. Clinical and radiological data were reviewed.

Results: This series comprises 18 patients (21 procedures) with a mean age of 47 years. Of the 15 symptomatic patients, 10 presented (67%) with a subarachnoid hemorrhage. Aneurysms most frequently arose from the basilar tip (61%), were of small size (50%), and had saccular morphology (78%). Aneurysm treatment was successful on first attempt in 90% and after a second attempt via the same approach in 100%. Oculomotor and TN palsies were noted postoperatively in three patients and one patient, respectively; all were transient. No procedure-related mortality occurred.

Conclusion: We describe a modified technique of tentorial incision in which dissection of the TN from its DC is essential. This technique optimized visibility and maneuverability by increasing the rostrocaudal exposure obtained via the extended subtemporal transtentorial route without significant postoperative TN deficit.