Use of the extreme lateral approach in the surgical treatment of an intradural ventral cervical spinal cord vascular malformation: technical case report

Vascular malformations on the ventral aspect of the spinal cord are difficult to access surgically. Recently, selected lesions have been treated with endovascular embolization. However, embolization using currently approved agents may not be permanently effective, and recanalization rates range from 25 to 83% in the literature. Additionally, many of these lesions are not amenable to endovascular treatment because of the inadequate diameter, tortuosity, or lack of collateral flow of the anterior spinal artery from which the feeding arteries arise. Surgical approaches to these lesions have been posterolateral or anterior. The posterolateral approach requires division of the dentate ligaments and occasionally the adjacent nerve root and then rotation of the cord itself to allow visualization of the lesion. The anterior approach involves a multilevel corpectomy requiring subsequent bone grafting and stabilization. Certain lesions are not readily approachable by either method. We describe the use of the extreme lateral approach to successfully access and obliterate a Type IVa perimedullary fistula located adjacent to the midline ventrally at the C1-C2 level in a 72-year-old woman who had suffered a subarachnoid hemorrhage. The extreme lateral approach was originally designed to access neoplasms located ventral to the cord and brain stem; as a result of the posterior displacement of the spinal cord by the neoplasm, intraoperative visualization is improved. No posterior displacement was present with this malformation. Even without such cord displacement, the extreme lateral approach allowed excellent visualization of and access to the arteriovenous fistula, preserved important anatomic structures, and required essentially no rotation or compression of the spinal cord to successfully obliterate the lesion.