Q) What do we tell a patient who has an unruptured cerebellar AVM?

A) Cerebellar AVMs make up < 15% of all brain AVMS. However, they have > 2 times the rate of hemorrhage compared to cerebral AVMs. Infratentorial AVM had the highest rupture rate, 12% per year in the first 5 years after diagnosis.  After 5 years, the rupture rate was 3.6% per year.   


They are more likely to have deep venous drainage. Patients with surgically treated cerebellar AVMS experienced poorer outcomes than supratentorial AVMs. Recent cerebellar AVMs database showed that preoperative neurological status (PrNS) was the strongest association with patient outcomes. Patients who presented with poor PrNs (mRS >2), almost 74% of patients remained in poor neurological status.    


Nisson et al reported the new proposed grading system of cerebellar AVMs which showed higher predictive accuracy of patient outcomes than Spetzler-Martin (SM), Spetzler-Ponce (SP), and Lawton-Young (LY) grading systems. (please see figure below)  


Nisson et al stated “Given the high morbidity and mortality rate associated with hemorrhage, a more aggressive treatment has been cited as an appropriate strategy. Further corroborating this practice, we found patients were afforded the greatest probability of experiencing a favorable outcome when treated early, prior to intracranial hemorrhage and/or preoperative decline in neurological status. These risk-benefits are not restricted to only surgery and would likely apply to nonoperative methods as well, such as radiosurgery, embolization, or both”. 


  1. Nisson PL, Fard SA, Walter CM, et al. A novel proposed grading system for cerebellar arteriovenous malformations [published online ahead of print, 2019 Mar 8]. J Neurosurg. 2019;1-11. 


  1. Hernesniemi JA, Dashti R, Juvela S, Väärt K, Niemelä M, Laakso A. Natural history of brain arteriovenous malformations: a long-term follow-up study of risk of hemorrhage in 238 patients. Neurosurgery. 2008;63(5):823-831.