Neurology
Fisher Grade
Predicts the risk of cerebral vasospasm after subarachnoid hemorrhage.
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Parameters
Fisher Grade Result
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Formula
Classification assigned based on the thickness and distribution of blood on initial non-contrast head CT.Clinical Pearls
Aids in deciding the intensity of neurocritical care monitoring and the need for prophylactic measures (like nimodipine) against vasospasm, which typically peaks 4-14 days post-bleed.
Limitations
The original scale has been criticized because Grade 3 has a higher risk of vasospasm than Grade 4. The Modified Fisher Scale (mFS) was later developed to correct this non-linear relationship.