LAUSR

A 49 y.o. female presented with sudden onset headache and meningismus. CT scan revealed a posterior fossa subarachnoid hemorrhage extending from the foramen magnum to the ambient cistern. Angiography showed a pial extramedullary arteriovenous malformation (AVM) at the lateral ventral surface of the cervicomedullary junction with primary supply from the left posterior inferior cerebellar artery (PICA), and dominant drainage into the anterior median perimedullary vein. Embolization of the AVM was considered high-risk as feeding arteries originated from the proximal lateral medullary segment of the left PICA. A far lateral approach with suboccipital craniotomy and C1-C2 laminectomy was performed. PICA was disconnected from the AVM, and multiple small feeders interrupted with bipolar cautery and aneurysm clips to achieve an in-situ occlusion of the pial AVM. Intraoperative indocyanine green video-angiography was used to define the AVM and critical en passant vessels prior to disconnection, and to demonstrate no residual early venous filling after the in-situ occlusion. Postoperative angiography demonstrated no residual arteriovenous shunting or nidiform vessels, with preservation of patency of the left PICA. The patient had an uneventful postoperative course and was discharged with no significant neurological deficits.