Long-Term Follow-Up of Quality of Life after Gamma Knife Radiosurgery Treatment for Arteriovenous Malformations

Introduction: Gamma Knife radiosurgery (GKR) is a standard treatment modality for intracranial arteriovenous malformations (AVMs). The efficacy and safety of this procedure is well accepted; yet, there is a relative lack of long-term studies in the literature to support its low morbidity. The goal of this study is to obtain quality of life and complication rate data at long-term follow-up on patients with AVMs treated by GKR. Methods: We independently reviewed 177 GKR procedures performed between 1989 and 2001 at a single institution for the treatment of intracranial AVM. Through chart review and direct patient contact, we attained greater than 4-year follow-up on 40 patients. Clinical outcome was evaluated using a modified Rankin scale. For statistical analysis, we constructed scatter plots and comparison of variables using Student’s t-testing to investigate predictors of clinical outcome after GKR. Results: Average follow-up was 100 ± 52 months (range, 48-189). Average pre-operative Rankin score was 1 ± 0.6 (range, 0-2), compared to average post-operative Rankin score of 0.8 ± 0.7 (p = 0.003). 33 patients (83%) had the same pre and post Rankin score, seven patients (17%) improved, and no patients worsened. Only two patients (5%) experienced major complications defined as requiring surgery for radiation necrosis, occurring at 36 and 64 months. Four others (10%) suffered minor transient neurological events, which were self-limited or resolved with medical therapy. No correlation was found between outcome and AVM grade, location, method of presentation, age of patient, or radiation dosing parameters. Conclusion: GKR is a safe and effective modality for the treatment of AVM. The immediate impact of treatment on quality of life is minimal. However, we recommend extended follow-up of these patients for surveillance of potential long-term complications.