The BNI (Barrow Neurological Institute) classification for subarachnoid hemorrhages was first described in 2012[^1] and relates the imaging extent of a subarachnoid hemorrhage to the risk of developing vasospasms.
Classification
BNI grade | Maximum SAH layer thickness (mm) | Incidence of symptomatic vasospasms (%) |
BNI grade 1 | No subarachnoid hemorrhage visible on imaging | 0 |
BNI grade 2 | ≤ 5 | 12.5 |
BNI grade 3 | >5 to 10 | 21.6 |
BNI grade 4 | >10 to 15 | 29.6 |
BNI grade 5 | >15 | 50 |