Keyhole Mini-Pterional Craniotomy for Clipping of Bilateral Middle Cerebral Artery Aneurysms.

Middle cerebral artery aneurysms remain excellent candidates for microsurgical treatment, despite proliferation of new endovascular tools. Nonetheless, patients desire less invasive options for permanent, durable treatment of aneurysms; this is particularly the case for patients presenting without subarachnoid hemorrhage and patients with multiple aneurysms that may require several surgical approaches. Keyhole craniotomies, when properly used in well-selected patients, allow for minimally invasive treatment of both ruptured and unruptured cerebral aneurysms, including bilateral aneurysms, which may be treated from a single approach. Middle cerebral artery bifurcation aneurysms are ideal for application of the keyhole concept, as they are located at the depth from the skull under a direct, linear path of access; obtaining early proximal control of the inflow vessel can be accomplished with minimal further dissection at the depth of a narrow corridor; there are few perforators that require dissection; a properly placed craniotomy exposes the entire proximal sylvian fissure as well as the contralateral sylvian contents; sharp dissection of the sylvian fissure further expands the corridor, which can be illuminated with lighted instruments as needed; and conversion to a larger craniotomy can be easily performed is bailout is necessary. A relative contraindication of this approach is if both aneurysms are laterally projecting, although in experienced hands this remains only a relative contraindication. A possible potential complication that the surgeon should be prepared for beforehand is intraoperative rupture of the distal aneurysm, but as demonstrated in Video 1, it is critical that the surgeon obtain proximal and distal control of the most distal aneurysm as would be obtained from an ipsilateral approach. We demonstrate in Video 1 the use of this approach for bilateral unruptured middle cerebral artery aneurysms, highlighting nuances for successful performance of this operation.