Spontaneous disappearance of intracranial arterio-venous malformations.

4 cases of spontaneous disappearance of intracranial arteriovenous malformations are reported. All the malformations were in the rolandic-parietal area, and fed in most cases by the MCA. In one case, the malformation was associated with a proximal aneurysm. One malformation was large, one medium-sized, and two small. Venous drainage was towards the longitudinal sinus in all cases. Presenting symptoms consisted of epilepsy in 2 cases, and intracerebral haemorrhage in 2 cases. Disappearance of the AVM was documented by angiography from 1 to 15 years after diagnosis, and was preceded by a new haemorrhage in 2 cases. Acute or gradual thrombosis of the AVM is suggested as the most likely cause of the disappearance of an AVM. Spontaneous thrombosis of an AVM should be considered as an aspect of the pathological entity known as "thrombosed AVM". Guidelines for the management of patients exhibiting spontaneous disappearance of an AVM are briefly discussed.