Abstract
We presented eight cases of arteriovenous malformation in the vincity of the medulla oblongata, located ventrolaterally at the cervicomedullary junction.
All patients developed subarachnoid hemorrhage and the initial symptoms were not specific except for severe nuchal rigidity and headache. Four cases were surgically treated. Satisfactory results were obtained by clipping of the feeding arteries and coagulation of the abnormal vessels with a bipolar coagulator. Three patients died, and two of them were autopsied.
Bilateral vertebral angiography is the best method for diagnosis and the open mouth projection is essential because shortened vascular figures of vertebral arteries can be corrected and because abnormal vessels can usually be found in the open mouth space. In our cases the C2 radiculomedullary artery, anterior spinal artery, posterior spinal artery and the abnormally dilated artery branching from the posterior inferior cerebellar artery and vertebral artery to flow into the lateral-inferior portion of the madulla oblongata participated as feeding arteries. The draining veins empty into the anteromedian medullary vein, transverse pontine vein and petrosal vein cranially and into the desending anterior spinal vein and intervertebral venous plexus caudally.
As the lesions were located at the lateral and ventral surface of the medulla oblongata, total removal was difficult by surgical procedures. If the anterior spinal artery is not the main feeding artery, the purpose of the operation can be attained by clipping or ligaturing the other feeding arteries and then coagulating the arteriovenous malformation located in the medulla oblongata. It is impossible to treat this surgically by the dorsal approach. It may be necessary to resort to other methods, such as the transclival approach.
