1. Michael T. Lawton, M.D. Department of Neurological Surgery, University of California, San Francisco, San Francisco, California Neurosurgery 2003, April, Volume 52, Number 4

2. A Supplementary Grading Scale for Selecting Patients with Brain Arteriovenous Malformations for Surgery Neurosurgery 2010, April, Volume 66, Number 4 Michael T. Lawton, M.D. Department of Neurological Surgery, University of California, San Francisco, San Francisco, California

3. Methods - Neurosurgery 2003 174 AVM’s (174 patients) in 4.8 years - 76 AVMs (45.2%) were Grade III - Consecutive analysis

4. Why study Grade III? Low-grade AVMs (Grades I and II) have low morbidity rates (0–5%) associated with their resection Surgery High-grade AVMs (Grades IV and V) have high morbidity rates (12-38%) associated with their resection Monitorization

5. Why study Grade III? Heterogenous: 4 different combination - Size - Venous drainage - Eloquence

6. Combinations: - S1V1E1 - S2V1E0 - S2V0E1 - S3V0E0

7. ??????????? S ize: 1 = < 3cm 2 = 3 -6 cm 3= > 6cm V enous drainage: 0 = Superficial 1 = Deep E loquence: 0 = No 1 = Yes

8. Results Improved Unchanged Worse Dead Lost to monitoring Total S1V1E1 18 (51.4%) 15 (42.9%) 0 (0.0%) 1 (2.9%) 1 (2.9%) 35 S2V1E0 4 (28.6%) 9 (64.3%) 1 (7.1%) 0 (0.0%) 0 (0.0%) 14 S2V0E1 9 (33.3%) 14 (51.9%) 2 (7.4%) 2 (7.4%) 0 (0.0%) 27 S3V0E0 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 Total 31 (40.8%) 38 (50.0%) 3 (3.9%) 3 (3.9%) 1 (1.3%) 76

9. Modification of the Spetzler-Martin grading scale S1V1E1 = S&M III- can be safely treated with microsurgical resection S2V0E1 = S&M III+ have higher than expected surgical risks and might be better managed conservatively (like many high-grade AVMs) S2V1E0 = S&M III require carefully individualized treatment recommendations and planning S3V0E0 = S&M III* are either nonexistent or exceedingly rare, with a surgical risk that is unclear