**5. Grading of cAVMs**

Before starting the management of cAVMs, all management risks should be considered, starting from those associated with diagnosis, surgical intervention, radiotherapy, to interventional radiology. Treating physicians should also consider both early and late complications such as hemorrhage and convulsions. There are many grading systems that may help physicians to assess the risk of these complications, take appropriate intervention for each patient, predict prognosis, and standardize patient's evaluation for scientific study purposes [21–23].
