Microsurgical Treatment of Foramen Magnum Cognard Type V Dural Arteriovenous Fistula: 2-Dimensional Operative Video.

Abstract

Cognard type V dural fistulas represent a rare and unique entity, and present clinically with myelopathy. They are frequently located around the foramen magnum and are most commonly fed by dural branches of the vertebral and external carotid artery. Detection requires meticulous angiography to define the angioarchitecture of the fistula, which in turn defines the treatment modality. We present the case of a 63 yr old woman, after informed consent was obtained, with prolonged, severe and progressive lower extremity myelopathy for 6 yr, with T2-weighted signal changes in the thoracic spinal cord on magnetic resonance imaging (MRI). Cervical MRI was unremarkable. Following computed tomography (CT), angiography of the spinal canal that revealed tortuous and dilated veins on the thoracic spinal cord surface, catheter angiography was performed. This demonstrated a fistula in relation to a dural branch of left vertebral artery with a characteristic single draining vein coursing caudally to the thoracic level, with delayed outflow suggestive of venous hypertension. Given the fact that the dural feeder was tortuous and relatively small, thus, precluding distal microcatheter access, and with presence of a single accessible draining vein, microsurgical treatment was preferred. Following a midline suboccipital craniotomy in prone position, a limited vertical dural opening was performed. Careful microsurgical arachnoid dissection revealed the arterialized draining vein with the aid of Indocyanine Green angiography. The draining vein was clipped, coagulated, and disconnected. Postoperative recovery was uneventful and the patient is undergoing rehabilitation therapy. Follow-up angiography showed complete elimination of the fistula. Salient teaching points are narrated at conclusion.