To evaluate the safety and efficacy of onyx for embolization of brain arteriovenous malformations (BAVM).

A prospective, multicenter study was conducted in France to evaluate embolization of BAVM with onyx. From May2003 to March2005, 50patients (26females, 24males; mean age: 34.8years, range: 16–64years) were included. Clinical presentation was haemorrhage in 22patients (44.0%), seizures in 16patients (32.0%), headaches in six patients (12.0%) and progressive neurological deficit in two cases (4.0%). Four patients were asymptomatic (8.0%).

One hundred and forty-ninesessions of embolization were performed: one to eight sessions/patient with a mean of 3.0sessions. One hundred and sixteen sessions (77.9%) were performed with onyx, 20sessions (13.4%) with glue and 13sessions (8.7%) with onyx and glue. Symptomatic acute postembolization haemorrhage (APEH) was observed in four cases (8.0% per patient). At 1month, morbidity and mortality related to the treatment were of 8% and 2%, respectively. Complete BAVM occlusion was obtained in 8.3% of cases. In the remaining cases, occlusion rate was between 99 and 80% in 56.3% of patients, 79 and 60% in 16.7%, and less than 60 in 18.7%. In case of incomplete occlusion, complementary treatment was performed by radiosurgery.

Onyx is suitable for BAVM embolization with acceptable morbidity and mortality.