[Fusiform aneurysm of the vertebral artery presenting with foramen magnum syndrome: a case report].

A 33-year-old male developed stiffness of the left neck and pain of the left shoulder two years previously. Six months prior to admission, he noticed tingling sensation of the left 2nd, 3rd and 4th fingers and motor weakness of the left hand, both of which gradually progressed. On admission, positive neurological findings were neck pain on dorsal extension, left hemiparesis more advanced in the upper limb, diffuse muscle atrophy of the left upper limb, hyperreflexia of the left upper and lower limbs with positive Babinski sign and dysesthesia corresponding to the left C3-T5 sensory dermatomes. Enhanced CT and Metrizamide CT myelography showed a large extra- and intra-dural mass from the C1 segment to the medulla oblongata on the left. Angiography disclosed a fusiform aneurysm of the left vertebral artery. Proximal ligation of the left vertebral artery was performed. Postoperatively, clinical signs were markedly improved and shrinkage of the aneurysm was demonstrated on postoperative Metrizamide CT myelogram. Pathogenesis of diffuse muscle atrophy of the left upper limb was undetermined, but was probably not due to disturbance of the anterior spinal artery because of good visualization of the artery on the angiogram. Indication of the proximal ligation of the vertebral artery with an aneurysm was discussed.