STEREOTAXIC RADIOSURGICAL TREATMENT OF CEREBRAL ARTERIOVENOUS-MALFORMATIONS

Objective: To assess the role of clinical factors, size of lesion, sit e of involvement, and radiation dose in patients with cerebral arterio venous malformations (AVMs) who underwent stereotactic radiosurgical t reatment. Design: We reviewed the results in 121 patients with cerebra l AVMs treated with the Leksell ''Gamma Knife'' between January 1990 a nd December 1993 at the Mayo Clinic in Rochester, Minnesota, Material and Methods: The following strict dose-volume protocol was used: AVMs 2.0 cm or smaller in diameter (volume, 4.2 cm(3) or less) received 20 Gy to the margin of the nidus, those between 2.1 and 3.0 cm in diamete r (4.3 to 14.1 cm(3)) received 18 Gy to the margin, and those that exc eeded 3.0 cm in diameter (more than 14.1 cm(3)) received 16 Gy to the margin. Lesions that involved the brain stem received a radiosurgical dose of 18 Gy or less to the margin, Patients participated in regular follow-up clinical and imaging studies for up to 55 months. Results: F ollow-up cerebral angiography in 43 patients demonstrated total oblite ration of the AVM nidus in 31 (72.1%), including 5 of 7 (71.4%) who ha d AVMs with a volume larger than 10 cm(3). Clinical follow-up revealed that 111 patients (91.7%) had a stable or improved outcome, 3 had a n onfatal AVM hemorrhage, 2 suffered a fatal hemorrhage, and 2 died of c auses not directly attributed to the AVM or radiosurgical treatment, T wo patients had new or increased, nondisabling neurologic deficits as a result of treatment, and one patient had a temporary partial eyelid ptosis. Conclusion: Our findings suggest that previous theories about the relationship between AVM size and rate of obliteration after radio surgical treatment may need revision, Our experience confirms that rad iosurgical treatment for cerebral AVMs is safe and effective, even in cases for which the latency period before obliteration is longer than 2 years.