[Natural history and spontaneous prognosis of cerebral arteriovenous malformations]

Eight large series of patients presenting with untreated cerebral arterio-venous malformations (A.V.M.) were reviewed. Data were gathered on 1134 patients who were followed for 20 years or more. The risk of rupture and the rate of other complications were estimated, in relation with other factors like age of patient, size of A.V.M., or hemodynamic stresses. The prevalence of A.V.M. at autopsy is 14 per 10,000 population. Fifty percent of A.V.M.s remain asymptomatic during the whole patient's life. The risk of hemorrhage from rupture of an A.V.M. is 2% per year and per patient. Hemorrhage is more frequent from small-sized A.V.M.s, mostly under certain hemodynamic factors. The risk of hemorrhage is also higher in children between 5 and 10 years of age, and in women to the end of pregnancy. The incidence of seizures and neurological impairment is approximately 1% per year and per patient, and these symptoms mostly occur in elder patients with large A.V.M.s. If the A.V.M. has not been revealed by hemorrhage, the risk of rupture is 1% per year and per patient. The incidence of complications from fortuitously diagnosed A.V.M.s seems very low, and even nil in some series. The risks of therapeutic procedures could not be determined, but in some A.V.M.s, the association of different therapeutic means seems mor advisable than isolated therapy. The analysis of natural history of A.V.M.s is desirable to provide a better information to the patient, and to define the limits of therapeutic indications.