Revision 10 for 'Modified Fisher scale'

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Modified Fisher scale

The modified Fisher scale is a method for grading subarachnoid hemorrhage (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 hemorrhage.

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 hemorrhage (SAH)
    • no intraventricular hemorrhage (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: 30%

 

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

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