The MGH aneurysm grade is based on 5 admission factors in a patient with an intracranial aneurysm. One point is given for each of the following factors:
- Age>50
- Size>10 mm
- Fisher Score of 3 or 4 (dense SAH or ICH)
- Hunt-Hess Score of 4 or 5 (patient is comatose)
- Giant Posterior Circulation lesion
For example, a 70 year old patient with an unruptured 13 mm anterior communicating artery aneurysm would have a score of 2 with a 20% chance of major disability according to the scale.
A 37 year old with a ruptured 6 mm PICA aneurysm with a Hunt-Hess score of 1 and Fisher score of 3 would obtain a score would have an MGH score of 1 with an expected very good outcome.
A 54 year old with an unruptured 5 mm posterior communicating aneurysm would have an MGH score of 1 with an expected excellent outcome.
Development of the grading system is described here and the PubMed citation is here.