Optimal treatment strategy of mesial occipital arteriovenous malformations (AVMs) requires meticulous preoperative planning and a tailored approach however microsurgical resection remains the most definitive treatment option. Their anatomical relationship to falx and the deep neurovascular structures make them amenable for being approached via a posterior interhemispheric (PIH) approach. We present the case of a ruptured Spetzler-Martin grade III, Spetzler-Ponce B mesial occipital AVM in a 49 year old male patient who presented to our institution. The patient had a small AVM nidus centered medial to the calcar avis of the left lateral ventricle who presented with hemorrhage within the splenium of the corpus callosum. The arterial supply to the AVM was from branches of the posterior cerebral artery and drainage was through a single vein to the vein of Galen. Given the patients young age, favorable AVM angioarchitecture and grading, multimodality treatment was indicated. He underwent preoperative onyx embolization prior to surgery. The AVM nidus had limited lateral extension, therefore we chose an ipsilateral PIH approach for resection. The ipsilateral approach allowed excellent exposure of the AVM nidus and draining vein without putting the uninvolved hemisphere at risk. Post operative cerebral angiography confirmed complete resection of the AVM. Understanding the angioarchitecture regarding the size of the nidus, the presence of AVM hemorrhage, and the degree of lateral extension can aid in deciding optimal patient positioning for this approach. Informed consent was obtained from the patient for the procedure and publication of his imaging.

Disclosures A. Kaul: None. R. Almefty: None. K. Erkmen: None.