A patient with aneurysmal subarachnoid hemorrhage undergoes CT scan showing diffuse thick subarachnoid blood in the basal cisterns, greater than 1 mm in vertical layers, with intraventricular hemorrhage. No intraparenchymal hematoma is present. What is the Fisher grade of this hemorrhage?

• A Fisher Grade 1
• B Fisher Grade 2
• C Fisher Grade 4
• D Fisher Grade 3 ✓

Explanation

Fisher Grade 3 is defined as diffuse thick subarachnoid clot (vertical layers >1 mm thick) without intraparenchymal or intraventricular hemorrhage. Grade 1 is no blood; Grade 2 is diffuse thin clot (<1 mm); Grade 3 is thick diffuse clot; Grade 4 is intracerebral or intraventricular hemorrhage with diffuse or no subarachnoid blood. Fisher grading predicts vasospasm risk. Grade 3 carries the highest risk of symptomatic vasospasm (Fisher et al., Neurosurgery; Greenberg, 9th ed.).

Reference: Greenberg's Handbook of Neurosurgery, 9th ed.

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