Surgical treatment of arteriovenous malformations of the posterior fossa.

Nine cases of arteriovenous malformations of the posterior fossa were operated upon, using microsurgical techniques. The excision was radical in eight patients. Seven of them, as well as the sole patient who had a partial removal of the malformation, returned to their previous occupations without neurological signs. In one case the preoperative deficit was unchanged. Some lesions that appear to penetrate the brain stem actually lie on its surface and can be dissected through an extrapial plane of cleavage. Extension of the malformation into the cerebellar peduncles requires dissection of the tangle and opening of the IVth ventricle.