Fisher grade

CT-based vasospasm risk after SAH

Group 1

No blood detected.

Group 2

Diffuse or vertical layers < 1mm thick.

Group 3

Localized clot and/or vertical layer >= 1mm (largest risk for delayed ischemic neurological deficit!)

Group 4

Intracerebral or intraventricular clot with diffuse or no SAH.


Greenberg's Handbook of Neurosurgery, 7th edition