Fractionated, stereotactic proton beam treatment of cerebral arteriovenous malformations

Objectives – To evaluate the therapeutic efficiency and adverse effects of stereotactic proton beam treatment of cerebral arteriovenous malformations (AVM). Material and methods – Twenty-six patients treated in Uppsala during 1991–97 were included (men = 14, women = 12; mean age = 39, range = 23–64). The nidus volumes ranged from 0.3 to 102 ml (mean = 24, median = 13). The follow-up included clinical evaluation, magnetic resonance imaging (and/or computed tomography) every 6–12 months for 3 years and final angiography. Results – The volume changes at final follow-up in AVMs >25 ml were −89, −85, −44, −29, −7, 0, 0, +5 and +18 (%); in AVMs 11–24 ml, −100, −100, −97, −92 and 0 (%); and in AVMs <10 ml, −100, −100, −100, −100, −100, −99, −98, −50, −0 and +40 (%). Two patients were lost to follow-up due to cerebral haemorrhage and myocardial infarction. Radiology displayed significant perifocal oedema in one patient and slight oedema in four patients. Of nine patients with epilepsy, seven became seizure-free after therapy while two continued to suffer from seizures. Conclusion – Proton beam irradiation is successful in a relatively high proportion of intermediate and large-sized cerebral AVMs. The adverse effects are acceptable. The advantage of proton treatment compared with gamma knife and LINAC stereotactic irradiation is that protons can irradiate even large volumes with a very sharp dose profile against normal surroundings. Thus, proton beam irradiation is a valuable option in the treatment of AVMs larger than 10 ml.