Treatment outcomes of Spetzler-Ponce grade A brain AVMs in a low-volume center: a systematic review and single institution experience

Arteriovenous malformations of the brain (bAVMs) are complex lesions in the treatment of which patient volumes and subsequent experience are likely to reflect on the outcome. We investigated whether a small neurosurgical center with a limited caseload can achieve similar results to larger centers in treatment of low grade bAVMs. We performed a systematic literature review of studies that have reported outcomes for Spetzler-Ponce A bAVM patients and completed a statistical analysis with a binary random-effects model (Simonian Laird). Since the definition of morbidity varied significantly between studies, we also grouped surgical and endovascular studies according to the definition. We examined treatment outcomes at our own institution and compared them to the literature. In the random effects model based on the literature review, surgery achieved a cure more consistently (98.2%, CI 97.3-99.2%, I² = 50.8) than embolization (71.0%, CI 61.5-80.5%, I² = 97.3) or radiosurgery (77.7%, CI 72.8-82.6%, I² = 90.0). Surgical morbidity (5.4%, CI 3.7-7.1%, I² = 85.3) in the literature was comparable to embolization (2.9%, CI 1.4-4.4%, I² = 43.1) and radiosurgery (6.2%, CI 1.6-10.7%, I² = 77.7). When studies were grouped according to the definition of morbidity, 9.5% experienced a new neurological deficit, 8.7% developed any worsening in mRS and 3.3% severely worsened in mRS after surgery. At our own institution in 1980-2019, 16.9% (14/83) developed any mRS worsening and 6.0% severely worsened in mRS after surgery. Treatment outcomes improved in 2010-2019 (after adoption of radiosurgery) in comparison to earlier decades (p = 0.213), with 11.7% (2/17) experiencing any and 0% (0/17) severe mRS worsening after surgery. Radiosurgical cure rate at our institution was 82.1% (23/28). While surgical morbidity at our institution has been somewhat higher than what is reported in the literature, outcomes have improved during the latest decade after adoption of radiosurgery. Radiosurgical outcomes at our institution were comparable to the literature. A small center can treat low grade bAVMs safely with surgery and radiosurgery given adequate training and proper patient selection.