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[Cranio-cervical junction dural arteriovenous malformation presenting with subarachnoid hemorrhage: report of two cases].

Most spinal dural arteriovenous malformations (AVMs) affect the thoracic and lumbar regions. The clinical features of dural AVMs are, usually, gradually progressing myelopathy, while hemorrhage is a rare occurrence. We have recently encountered two cases of cranio-cervical junction dural AVM which caused subarachnoid hemorrhage. Both patients, a 61-year-old and a 37-year-old man were admitted to our hospital due to sudden onset of severe headache. Left vertebral angiography demonstrated a dural AVM at the cranio-cervical junction. A left suboccipital craniotomy and left hemilaminectomy of the atlas were performed. Dural opening disclosed tortuous dilated abnormal vessels. The dural AVM was fed by multiple small dural branches of the left vertebral artery and drained into an intracranial pial vein. The dura where the left vertebral artery penetrated was coagulated and divided from the left vertebral artery. Postoperative courses of these patients were uneventful. The pathophysiology and surgical treatment of dural AVMs in the cranio-cervical junction are discussed.