Internal Maxillary to MCA Bypass: Infratemporal Approach to the Internal Maxillary Artery. Anatomy and Technique

Introduction: Internal maxillary artery (IMax)-to-Middle cerebral artery (MCA) has been recently described as an alternative to cervical EC-IC bypass to reduce the graft length which theoretically correlates with improved graft patency. The previously described technique utilizes a “key hole” craniectomy between V2 and V3 in the temporal fossa floor, thereby exposing the donor IMax through a small boney window. This limited access requires that the anastomosis be performed in a technically challenging end-to-side fashion. We describe a lateral subtemporal craniectomy of the middle cranial fossa floor to facilitate wide exposure of the IMax thereby resulting in a less demanding end-to-end proximal anastomosis.

Technique: Zygomatic osteotomy was used followed by fronto-temporal craniotomy and subsequently lateral temporal fossa craniectomy reaching its medial border designated by a virtual line connecting foramen rotundum and foramen ovale. In the first patient, the Imax was identified in the infratemporal fossa by neuronavigation coupled with microdoppler confirmation. In the subsequent patients, reliable anatomic landmarks were identified resulting in more rapid atraumatic location of the IMax, which was then confirmed by micordoppler

Results: There were three cases in which the technique was utilized. The first bypass was performed as flow augmentation for hypoperfused hemisphere. The other two were performed due to MCA giant aneurysms.

A saphenous vein graft was used in two patients. In the third patient a segment of brachiocephalic vein was used. The first patient was anastomosed as end-to-side while the subsequent two patients were done as end-to-end anastomoses. Post operative angiography demonstrated good filling of the graft with robust distal flow. There were no complications associated with the approach to the IMax. All patients tolerated the procedure well. One of the aneurysm patients had postoperative swelling of the hemisphere. He underwent decompressive craniectomy, recovered to his preoperative baseline and ultimately underwent cranioplasty.

Conclusions: The lateral temporal fossa craniectomy technique combined with zygomatic osteotomy resulted in reliable identification and wide exposure facilitating easy access to the Imax.