Grading Scales for Subarachnoid Hemorrhage - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 284

Table 4
Fisher grading scale for SAH

Fisher group Blood on CT

1 No SAH indentifi ed

2 Diffuse or vertical layers <1 mm thick

3 Localized clot and/or vertical thickness >1 mm

4 Intracerebral or intraventricular hemorrhage

was developed at time (circa 1980) when the resolution on CT
scanners was much less than those in common use today. Other
important variables that were not addressed when the Fisher scale
was developed also include density of blood clot and clot location
which are known to play a role in the clinical course of SAH ( 17 ).
Additional studies have attempted to utilize the Fisher grading
scale as a standalone mechanism to predict outcome with some
success ( 18 ). The issue becomes that the majority of patients fall
into a Fisher grade 3 as most SAH patients do not present with
either absent blood (grade I) or clot that is less than 1 mm in thickness
(grade II). More recently, outcome prediction based on the Fisher
scale has been bolstered with the addition of patient age, aneurysm
size, and aneurysm location. These adaptations to the Fisher scale
have predicted patient outcomes with some reliability but they have
as of yet been included in day-to-day management of the SAH
patient ( 17 ).
Higher resolution CT images and MRI sequences ( 19 ) play an
important role in the management of the SAH patient that was not
present when the Fisher scale was developed, however, their utility
in prediction of clinical outcomes remains in question and requires
additional study as stand-alone techniques.
With the explosion of new MRI techniques, the future predic-
tion models based on imaging studies alone will likely include the
use of diffusion tensor imaging, perfusion sequences and likely MR
spectroscopy. It does, however, remain to be seen if an imaging
modality without consideration of clinical picture will provide
additional predictive information.

7. Massachusetts
General Hospital
Scale

The Massachusetts General Hospital (MGH) aneurysm grade
(Table 5 ) ( 17 ) is assigned based on retrospective review of 409 patients
who had their aneurysms surgically treated with the patient's clinical
outcome as the primary goal of the study. Using a combination of