Modified system validated for superior prediction of DCI.
Diagnostic Analysis
Input CT findings regarding cisternal and ventricular blood to calculate risk of Delayed Cerebral Ischemia.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Superior alternative to the original Fisher scale for predicting Delayed Cerebral Ischemia (DCI).
Admission CT evaluation of aneurysmal SAH.
Identifying patients at high risk for symptomatic vasospasm who require ICU-level monitoring.
Section 2
Formula & Logic
Fronig-Claassen Algorithm
Score
Cisternal SAH (Thick)
IVH (Present)
0
No
No
1
Thin/Absent
Yes
2
Thick (≥ 1 mm)
No
3
Thin/Absent
Yes
4
Thick (≥ 1 mm)
Yes
Note on "Thick"
Thick blood is defined as a layer of subarachnoid blood ≥ 1 mm in depth in any cistern. Thin blood is < 1 mm.
Section 3
Pearls/Pitfalls
IVH as a Variable
The major enhancement in the Modified Fisher Scale is treating Intraventricular Haemorrhage (IVH) as an INDEPENDENT risk factor. In the original scale, IVH alone was Grade 4 and often seen as lower risk than Grade 3. In the Modified scale, SAH + IVH (Grade 4) is the highest possible risk.
Section 4
Evidence Appraisal
Primary Reference
Effect of cisternal and ventricular blood on risk of delayed cerebral ischemia after subarachnoid hemorrhage: the Fisher scale revisited
