Follow-up studies by cerebral angiography 4 to 11 years after the first angiography were carried out in six out of 44 cases with arteriovenous malformation of the brain (AVM) which were not operated on radically for various reasons. The size of the AVM was unchanged in five cases and spontaneous complete regression of the AVM was noted in one case. This 44 year-old man had a sudden attack of severe headache followed by disturbance of consciousness in April, 1968. Bloody CSF was noted in spinal taps. He was admitted in August, 1968. Vertebral angiography on admission showed an AVM of 1.4×1.1×1.0 cm in size in the left occipital lobe. The main feeder was the posterior cerebral artery and the drainer joined the vein of Galen. Craniotomy was performed, but no attempt was made to remove the AVM. Right hemiparesis and hemihypesthesia suddenly appeared and continued for 1 to 2 months four times from 1970 to 1978, but computerized tomography revealed no abnormal findings. The second angiography performed 10 years after the first study showed complete disappearance of the AVM. The same attack was noted in June, 1979 and the third study revealed reappearance of a small AVM.
Spontaneous disappearance of the AVM was also demonstrated in another case during admission. This 26 year-old man had a sudden attack of left hemiparesis in January, 1966. Right carotid angiography revealed a small AVM of 0.7×0.5×0.5 cm in size in the right parietal lobe. The main feeder was the pericallosal artery and the drainer joined the superior sagittal sinus. A small intracerebral hematoma was noted posterior to the AVM. He was treated conservatively. Angiography performed 3 months after the first study demonstrated complete disappearance of the AVM. The left hemiparesis recovered gradually and he returned to his job. No more attacks were noted for 7 years after discharge.
Ten cases, including the two present cases, showed spontaneous regression of the AVM and 33 cases with angiographically occult AVM were collected from the literature.
Thrombosis of the AVM associated with circulatory disturbance in and around the lesion due to repeated intracerebral bleeding from the AVM was suspected to be the main factor causing spontaneous disappearance of the AVM. Roles of advanced arteriosclerosis and the circulatory condition depending on the location of the AVM in spontaneous regression of the AVM were not clear in the present study.