Fisher Grade calculator
Result
Grade 1
Rare vasospasm
How to use it
- 1
Obtain CT head within 24h of SAH onset. Sensitivity ~98% within 6h; declines thereafter.
- 2
Measure blood thickness in basal cisterns. Fisher 3 = thick clot (≥1mm in subarachnoid space).
- 3
Grade 3 highest vasospasm risk. Paradoxically Grade 4 (IVH) has lower vasospasm rate — blood cleared rapidly.
When to use it
- Nimodipine dosing protocol
- All SAH grades: nimodipine 60 mg Q4H for 21 days (reduces vasospasm deficit).
- TCD monitoring
- Grade 3: more aggressive TCD monitoring for vasospasm days 4–14.
- Modified Fisher
- Modified Fisher 3 = focal thick AND IVH — improves prediction over original.
A reference for clinicians and students, not medical advice. A score supports a decision; it does not make one. Check every result against the patient in front of you and your local protocol.
At a glance
- Specialty
- Neurology
- Inputs
- 1
- Type
- Points score
