"Tangential" resection of medial temporal lobe arteriovenous malformations with the orbitozygomatic approach.

OBJECTIVE

Arteriovenous malformations (AVMs) of the medial temporal lobe are usually resected through subtemporal-transcortical approaches that provide a trajectory that is perpendicular to the plane of the AVM. The pterional approach is sometimes used for AVMs in the uncus and amygdala, but it is not recommended for AVMs in the hippocampal region because it provides a "tangential" approach with limited access to posterior feeding arteries and draining veins. The orbitozygomatic approach enhances exposure along this tangential trajectory and was used in a consecutive series of 10 patients to determine its advantages.

METHODS

During a 5.7-year period, 43 patients underwent resection of temporal lobe AVMs, 10 of which were located in the medial temporal lobe (amygdala and uncus [Region A] or hippocampus, parahippocampus, and fusiform gyrus [Region B]). AVMs were evenly distributed by region and by hemispheric dominance and included two Spetzler-Martin Grade IV lesions. An orbitozygomatic approach was used in all cases.

RESULTS

Complete resection was accomplished in nine patients, and one patient underwent multimodality management with postoperative stereotactic radiosurgery. Good outcomes (Rankin outcome score <or=2) were observed in all patients, and six patients were improved neurologically at late follow-up (mean, 1.3 yr). No permanent language deficits were produced by this approach.

CONCLUSION

The orbitozygomatic approach maximizes the exposure of the tangential approach to medial temporal lobe AVMs and has advantages over traditional lateral approaches. It provides early access to critical feeding arteries from the anterior choroidal artery, posterior cerebral artery, and posterior communicating artery; it minimizes temporal lobe retraction and risk to the vein of Labbé; and it avoids transcortical incisions or lobectomy that might impact language and memory function. For these reasons, it may be the optimal approach for small- and medium-sized compact AVMs in the dominant medial temporal lobe.