Modified Fisher scale

The modified Fisher scale is a method for grading subarachnoid haemorrhage (SAH) seen on CT. It was developed from the original Fisher scale which was modified to account for patients with thick cisternal blood and concomitant intraventricular (IVH) or intraparenchymal haemorrhage.

Moreover, the risk of developing vasospasm progressively increases with each level of the modified Fisher grade. Whereas the risk was highest for Grade 3 and then decreased for Grade 4 while using the original Fisher scale.

Classification

  • grade 0
    • no subarachnoid haemorrhage (SAH)
    • no intraventricular haemorrhage (IVH)
    • incidence of symptomatic vasospasm: 0% 3
  • grade 1
    • focal or diffuse, thin SAH
    • no IVH
    • incidence of symptomatic vasospasm: 24%
    grade 2
    • thin focal or diffuse SAH
    • IVH present
    • incidence of symptomatic vasospasm: 33%
  • grade 3
    • thick focal or diffuse SAH
    • no IVH
    • incidence of symptomatic vasospasm: 33%
  • grade 4
    • thick focal or diffuse SAH
    • IVH present
    • incidence of symptomatic vasospasm: 40%

Note: thin SAH is < 1 mm thick and thick SAH is >1 mm in depth. 

Differences between the Fisher scale and modified Fisher scale 4, 5
  • in Fisher scale no SAH is grade 1 (grade 0 in modified Fisher scale)
  • in Fisher scale thin SAH, no IVH is grade 2 (grade 1 in modified Fisher scale)
  • in Fisher scale thick SAH with no IVH is grade 3 (grade 3 in modified Fisher scale)
  • in Fisher scale any IVH is grade 4, irrespective of presence of SAH (in modified Fisher scale it is either grade 2 if thin or no SAH, or grade 4 if thick SAH)

See also

Stroke and intracranial haemorrhage
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Article information

rID: 41101
Synonyms or Alternate Spellings:
  • Modified Fisher scale in subarachnoid haemorrhage

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Cases and figures

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    Case 1: modified Fisher grade 4
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