The Fisher grading system uses CT-findings within 5 days of onset of a subarachnoid haemorrhage to evaluate risk of vasospasm. It looks primarily at amount and distribution of blood in the ventricular system. The original publication (abstract) by Fisher et al (1980) can be viewed here.
Grade 1: No blood
Grade 2: Diffuse or thin layer of blood less than 1 mm thick (interhemispheric, insular, or ambient cisterns)
Grade 3: Localized clots and/or layers of blood greater than 1 mm thick in the vertical plane
Grade 4: Intracerebral or intraventricular clots with diffuse or absent blood in basal cisterns
A number of subsequent publications have evaluated its validity and compared it to newer grading systems:
- Lagares A, Gómez PA, Alen JF, Lobato RD, Rivas JJ, Alday R. A comparison of different grading scales for predicting outcome after subarachnoid haemorrhage. Acta Neurochir (Wien). 2005 Jan. 147(1):5-16; discussion 16. [Medline].
- Ogilvy CS, Carter BS. A proposed comprehensive grading system to predict outcome for surgical management of intracranial aneurysms. Neurosurgery. 1998 May. 42(5):959-68; discussion 968-70. [Medline].
- Klimo P Jr, Schmidt RH. Computed tomography grading schemes used to predict cerebral vasospasm after aneurysmal subarachnoid hemorrhage: a historical review. Neurosurg Focus. 2006. 21(3):E5. [Medline].
- Hijdra A, Brouwers PJ, Vermeulen M, van Gijn J. Grading the amount of blood on computed tomograms after subarachnoid hemorrhage. Stroke. 1990 Aug. 21(8):1156-61. [Medline].
- Jiménez-Roldán L, Alén JF, Gómez PA, Lobato RD, Ramos A, Munarriz PM. Volumetric analysis of subarachnoid hemorrhage: assessment of the reliability of two computerized methods and their comparison with other radiographic scales. J Neurosurg. 2013 Jan. 118(1):84-93. [Medline].