Natural history of arteriovenous malformations: analysis of non-radically treated patients

The natural history of cerebral arteriovenous malformations (AVMs) was studied in 115 patients with untreated or incompletely obliterated AVM. Sixty-six patients had histories of hemorrhage, 20 had seizures, 18 had progressive ischemic neurologic deficits and 8 had headache. Three patients had no symptoms attributable to the AVM. Twenty-seven (23%) AVMs rebled or newly bled and the cumulative bleeding or rebleeding rate was 72.5% (4.2% per year). The cumulative bleeding rate of the neurologic deficit group, however, was significantly lower than the cumulative rebleeding rate of the hemorrhagic group (P < 0.05) and that of the seizure group (P < 0.05). No significant differences were found in regard to the initial clinical manifestations. The cumulative survival rate was 84% and the average mortality rate was 1.4% per year. Fifty patients (43%) were below 90 in Karnofsky's Index at the end of the follow-up period and the average morbidity rate was 6.0% per year.