# Modified Fisher — Modified Fisher CT scale for aneurysmal subarachnoid hemorrhage

> Two-axis admission noncontrast-CT descriptor combining thin versus thick subarachnoid blood with presence versus absence of intraventricular blood. It stratifies population risk of symptomatic vasospasm or delayed cerebral ischemia; it does not diagnose SAH, detect current vasospasm or prescribe treatment.

**Situação:** vigente · **Órgão:** Encéfalo · **Órgão emissor:** Frontera et al. / neurocritical-care practice · **Versão:** 2006 derivation; NINDS CDE operationalization and evidence reviewed through 2026 · **Ano:** 2006

> ⚠️ Uma versão mais nova pode existir (em revisão).

## Procedência e vigência
- Família: léxico
- Tipo de lógica: flat
- Modalidade: CT
- Fonte primária: Frontera JA, Claassen J, Schmidt JM, et al.. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale (2006) — https://pubmed.ncbi.nlm.nih.gov/16823296/
- Última verificação: 2026-07-24
- Última checagem: 2026-08-12

## Lógica de decisão
Return the CT blood-burden axes, scan timing, definition provenance and uncertainty with the grade. Keep symptomatic vasospasm, angiographic vasospasm and DCI distinct, and never turn the category into a diagnosis or treatment order.

## Categorias

| Código | Rótulo | Critérios | Conduta | Risco | Localizador | Verificado |
| --- | --- | --- | --- | --- | --- | --- |
| 0 | Grade 0, no SAH and no IVH | On an adequate early noncontrast head CT, neither subarachnoid blood nor intraventricular blood is visible. Both must be absent. A delayed or technically limited negative CT does not exclude earlier SAH, and isolated IVH without visible SAH is outside the canonical five-category map rather than grade 0. | If aneurysmal SAH is suspected or established, continue the emergency diagnostic, aneurysm-securing and neurocritical-care pathway regardless of this category. Grade 0 does not justify reassurance, reduced surveillance or withholding nimodipine; the scan timing, clinical state and complete workup govern care. | Only 20 of 1,355 derivation participants were grade 0, so the investigators pooled grades 0 and 1 as the odds-ratio reference and did not provide a stable grade-0 probability. Do not attach the grade-1 rate or a near-zero vasospasm/DCI risk to an individual grade-0 scan. | Frontera et al. 2006, PMID 16823296, Methods and Table 1 for no SAH/no IVH and the 20-patient grade-0 sample; Results for the pooled grade 0-1 reference. Hoh et al. 2023 AHA/ASA guidance for grade-independent emergency care. | ✓ |
| 1 | Grade 1, thin SAH without IVH | Focal or diffuse thin subarachnoid blood is present and no intraventricular blood is visible. Record the maximal clot thickness and site plus the named thin/thick rule: the original 2006 paper supplied no reproducible universal measurement, while the current NINDS CDE uses less than 1 mm for thin and leaves exactly 1 mm unresolved. | Use the grade as blood-burden risk context within specialist aSAH care, not as a low-risk discharge or treatment rule. Prompt aneurysm evaluation and treatment, early enteral nimodipine, euvolemia and appropriate clinical/DCI surveillance follow current guidance and the patient state rather than being switched on or off by grade 1. | Symptomatic vasospasm occurred in 24% of grade-1 participants in the 1,355-patient derivation cohort; grades 0-1 formed the odds-ratio reference. Across five later studies with crude grade data, the mean DCI frequency for grades 0-1 combined was 21% (SD 7; range 5-24%). These different endpoints and historical cohorts are not an individual forecast. | Frontera et al. 2006, Methods and Table 2, modified Fisher row 1 (thin SAH, no IVH; 24% symptomatic vasospasm); NINDS CDE ModFisherScale v3.1 for the less-than 1 mm operational wording; van der Steen et al. 2019, Modified Fisher results for DCI synthesis. | ✓ |
| 2 | Grade 2, thin SAH with IVH | Focal or diffuse thin subarachnoid blood is present together with unequivocal intraventricular blood in any ventricle. Bilateral lateral-ventricular involvement is not required. Preserve the thickness definition and return 2-versus-4 if the thin/thick boundary is unresolved. | Treat aneurysmal SAH and any hydrocephalus or ventricular obstruction on their own clinical merits. Grade 2 supports risk-aware monitoring but does not by itself order CSF diversion, angiography, induced hypertension or endovascular rescue; new deterioration requires direct evaluation for DCI, vasospasm, hydrocephalus and other causes. | In the derivation cohort, 33% developed symptomatic vasospasm; the crude odds ratio was 1.58 (95% CI 1.02-2.46) versus pooled grades 0-1. Later studies reported a mean 26% DCI frequency (SD 9; range 0-33%) for grade 2. Endpoint, era and cohort heterogeneity preclude using either as a bedside probability. | Frontera et al. 2006, Methods and Table 2, modified Fisher row 2 (thin SAH with IVH; 33%; OR 1.58, 95% CI 1.02-2.46); Melinosky et al. 2021 abstract for any-ventricle definition awareness; van der Steen et al. 2019 for DCI context. | ✓ |
| 3 | Grade 3, thick SAH without IVH | Focal or diffuse thick subarachnoid blood is present and no intraventricular blood is visible. The original derivation did not define a universal thickness measurement; the qualified NINDS CDE uses more than 1 mm. An exact or rounded 1 mm measurement remains ambiguous and should be returned as grade 1-versus-3 rather than forced. | Use the larger subarachnoid blood burden to inform specialist surveillance while following the complete aSAH pathway. The category does not diagnose current arterial narrowing or DCI and does not independently trigger prophylactic hemodynamic augmentation, which current AHA/ASA guidance advises against. | In the derivation cohort, 33% developed symptomatic vasospasm; the crude odds ratio was 1.59 (95% CI 1.14-2.22) versus pooled grades 0-1. Later studies reported a mean 30% DCI frequency (SD 9; range 5-36%) for grade 3. These are group-level, endpoint-specific summaries rather than an individual probability. | Frontera et al. 2006, Methods and Table 2, modified Fisher row 3 (thick SAH, no IVH; 33%; OR 1.59, 95% CI 1.14-2.22); NINDS CDE v3.1 for more-than 1 mm wording; van der Steen et al. 2019 for DCI context; Hoh et al. 2023 for hemodynamic boundaries. | ✓ |
| 4 | Grade 4, thick SAH with IVH | Focal or diffuse thick subarachnoid blood is present together with unequivocal blood in any ventricle. Record clot distribution, maximum thickness and every involved ventricle. Hydrocephalus, intraparenchymal hemorrhage and other blood compartments are important companion findings but do not alter the code. | This is the highest ordinal blood-burden category and warrants full specialist aSAH attention, but it is not a treatment order. Use examination trajectory and appropriate TCD, CTA, CT perfusion or angiography to evaluate suspected vasospasm/DCI; treat hydrocephalus and symptomatic DCI based on their actual findings and physiology. | In the derivation cohort, 40% developed symptomatic vasospasm; the crude odds ratio was 2.20 (95% CI 1.58-3.05) versus pooled grades 0-1. Later studies reported a mean 42% DCI frequency (SD 9; range 34-83%) for grade 4. The wide range and distinct endpoint make a fixed individual risk claim unsafe. | Frontera et al. 2006, Methods and Table 2, modified Fisher row 4 (thick SAH with IVH; 40%; OR 2.20, 95% CI 1.58-3.05); van der Steen et al. 2019 Modified Fisher results for DCI context; Hoh et al. 2023 AHA/ASA points 6-8 for surveillance and symptomatic-DCI care. | ✓ |

### Citações por categoria
- **0**: Frontera JA, Claassen J, Schmidt JM, et al.. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale (2006) — https://pubmed.ncbi.nlm.nih.gov/16823296/ · Frontera et al. 2006, PMID 16823296, Methods and Table 1 for no SAH/no IVH and the 20-patient grade-0 sample; Results for the pooled grade 0-1 reference. Hoh et al. 2023 AHA/ASA guidance for grade-independent emergency care.
- **1**: Frontera JA, Claassen J, Schmidt JM, et al.. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale (2006) — https://pubmed.ncbi.nlm.nih.gov/16823296/ · Frontera et al. 2006, Methods and Table 2, modified Fisher row 1 (thin SAH, no IVH; 24% symptomatic vasospasm); NINDS CDE ModFisherScale v3.1 for the less-than 1 mm operational wording; van der Steen et al. 2019, Modified Fisher results for DCI synthesis.
- **2**: Frontera JA, Claassen J, Schmidt JM, et al.. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale (2006) — https://pubmed.ncbi.nlm.nih.gov/16823296/ · Frontera et al. 2006, Methods and Table 2, modified Fisher row 2 (thin SAH with IVH; 33%; OR 1.58, 95% CI 1.02-2.46); Melinosky et al. 2021 abstract for any-ventricle definition awareness; van der Steen et al. 2019 for DCI context.
- **3**: Frontera JA, Claassen J, Schmidt JM, et al.. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale (2006) — https://pubmed.ncbi.nlm.nih.gov/16823296/ · Frontera et al. 2006, Methods and Table 2, modified Fisher row 3 (thick SAH, no IVH; 33%; OR 1.59, 95% CI 1.14-2.22); NINDS CDE v3.1 for more-than 1 mm wording; van der Steen et al. 2019 for DCI context; Hoh et al. 2023 for hemodynamic boundaries.
- **4**: Frontera JA, Claassen J, Schmidt JM, et al.. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale (2006) — https://pubmed.ncbi.nlm.nih.gov/16823296/ · Frontera et al. 2006, Methods and Table 2, modified Fisher row 4 (thick SAH with IVH; 40%; OR 2.20, 95% CI 1.58-3.05); van der Steen et al. 2019 Modified Fisher results for DCI context; Hoh et al. 2023 AHA/ASA points 6-8 for surveillance and symptomatic-DCI care.

## Referências cruzadas
- _fronteira compartilhada_ → [Fisher — Original Fisher CT grouping for aneurysmal subarachnoid hemorrhage](https://radcommons.laudos.ai/systems/fisher.md) — Refinement of the original Fisher scale.
- _fronteira compartilhada_ → [Hunt-Hess — Hunt and Hess clinical grading of aneurysmal subarachnoid hemorrhage](https://radcommons.laudos.ai/systems/hunt-hess.md) — CT blood burden grade complementing the Hunt and Hess clinical grade.

## Histórico de versões

| Data | Evento | Detalhe | Situação |
| --- | --- | --- | --- |
| 2026-07-25 | revised | Monitored source changed (content_hash). Detected automatically; awaiting reviewer confirmation. | needs_review |
| 2006-07-01 | published | Frontera and colleagues published the five-category modified Fisher CT scale and its symptomatic-vasospasm derivation in 1,355 SAH trial participants. | confirmed |


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> Conteúdo de referência reescrito. Confira a publicação primária vigente. Não é dispositivo médico nem substitui o julgamento clínico. O radiologista responsável pelo laudo permanece o autor e o responsável.

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