Fisher Grade (SAH)
Grades amount of subarachnoid blood on CT to predict vasospasm risk
Score interpretation
No subarachnoid blood seen, or diffuse thin blood: severe vasospasm in 1 of 18 patients (Fisher 1980).
→ Standard SAH management; nimodipine; serial TCD/neurological monitoring
Localised clot or layers ≥ 1 mm thick: severe vasospasm followed in 23 of 24 patients (Fisher 1980).
→ ICU monitoring; early aneurysm treatment; vasospasm prevention protocol; daily TCD
Not a high-vasospasm group in Fisher 1980, but intraventricular blood raises the risk of delayed ischaemia in later series — consider the modified Fisher scale.
→ Standard SAH management; neurosurgical review for hydrocephalus or haematoma; serial neurological monitoring
Interpretation bands for the Fisher Grade. Apply clinical judgement and local guidance.
References
- Fisher CM, et al. Relation of cerebral vasospasm to subarachnoid hemorrhage visualized by computerized tomographic scanning. Neurosurgery. 1980;6(1):1–9.
Related
Curated clinical cross-links plus same-class fallbacks.
- Difficult Airway Algorithm (DAS) · DAS 2015; Royal College of Anaesthetists
- Major Haemorrhage Protocol · NICE NG24; UK MHP guidelines
- New-Onset Atrial Fibrillation · ESC 2020 AF Guidelines; NICE NG196
- Hypertensive Emergency · ESC/ESH 2018 Hypertension Guidelines; NICE NG136
- Bradycardia Management · Resuscitation Council UK ABCDE; ESC 2021 Pacing Guidelines
- Ventricular Tachycardia / Fibrillation · Resuscitation Council UK ACLS; ESC 2022 Ventricular Arrhythmia Guidelines
Featured in these MRCEM clinical pathways
The Fisher Grade is covered in detail — with RCEM/NICE evidence base, indications and pitfalls — in the following exam-focused pathways on our sister siteReviseMRCEM.
MRCEM Primary / Intermediate / OSCE candidates: each pathway includes exam-style questions, RCEM/NICE citations, and FAQ summaries.
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.