The Fisher scale is used to assess the amount of blood visible on a CT scan following subarachnoid hemorrhage. Higher Fisher grades are associated with a worse prognosis and increased mortality.
1
No hemorrhage is evident.
2
Subarachnoid hemorrhage less than 1mm thick.
3
Subarachnoid hemorrhage is more than 1mm thick.
4
Subarachnoid hemorrhage of any thickness with intraventricular hemorrhage (IVH) or parenchymal extension. 1).
see Modified Fisher Grading Scale for Subarachnoid Hemorrhage
Elderly patients, and especially the subgroup with a Fisher Scale 3 bleeding pattern, had a high risk for an unfavorable outcome, whereas the subgroup of Non perimesencephalic subarachnoid hemorrhage NPM-SAH without a Fisher Grade 3 bleeding pattern had a favorable outcome, similar to perimesencephalic subarachnoid hemorrhage (PM)-SAH.