Modified Fisher Scale


The Modified Fisher grading scale classifies the appearance of subarachnoid hemorrhage on head CT scan and is used in predicting cerebral vasospasm. The amount and location of hemorrhage seen on the initial head CT scan correlates with the risk of developing vasospasm. The modified Fisher scale accounts for thick cisternal and ventricular blood, features that distinguish it from the conventional Fisher scale.

The development of clinical vasospasm within each grade has been reported as follows:

  • Grade 1 = 6%
  • Grade 2 = 15%
  • Grade 3 = 35%
  • Grade 4 = 34%


Frontera JA, et al.

Neurosurgery 2006, 59 (1): 21-7; discussion 21-7

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1. Appearance of Hemorrhage?

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