Classification
There are several grading scales available for SAH. The Glasgow Coma Scale is ubiquitously used for assessing consciousness. Three specialized scores are used to evaluate SAH; in each, a higher number is associated with a worse outcome. These scales have been derived by retrospectively matching characteristics of patients with their outcomes.
The first scale of severity was described by Hunt and Hess in 1968:
| Grade | Signs and symptoms | Survival |
|---|---|---|
| 1 | Asymptomatic or minimal headache and slight neck stiffness | 70% |
| 2 | Moderate to severe headache; neck stiffness; no neurologic deficit except cranial nerve palsy | 60% |
| 3 | Drowsy; minimal neurologic deficit | 50% |
| 4 | Stuporous; moderate to severe hemiparesis; possibly early decerebrate rigidity and vegetative disturbances | 20% |
| 5 | Deep coma; decerebrate rigidity; moribund | 10% |
The Fisher Grade classifies the appearance of subarachnoid hemorrhage on CT scan.
| Grade | Appearance of hemorrhage |
|---|---|
| 1 | None evident |
| 2 | Less than 1 mm thick |
| 3 | More than 1 mm thick |
| 4 | Diffuse or none with intraventricular hemorrhage or parenchymal extension |
This scale has been modified by Claassen and coworkers, reflecting the additive risk from SAH size and accompanying intraventricular hemorrhage (0 - none; 1 - minimal SAH w/o IVH; 2 - minimal SAH with IVH; 3 - thick SAH w/o IVH; 4 - thick SAH with IVH);.
The World Federation of Neurosurgeons (WFNS) classification uses Glasgow coma score (GCS) and focal neurological deficit to gauge severity of symptoms.
| Grade | GCS | Focal neurological deficit |
|---|---|---|
| 1 | 15 | Absent |
| 2 | 13–14 | Absent |
| 3 | 13–14 | Present |
| 4 | 7–12 | Present or absent |
| 5 | <7 | Present or absent |
A comprehensive classification scheme has been suggested by Ogilvy and Carter to predict outcome and gauge therapy. The system consists of five grades and it assigns one point for the presence or absence of each of five factors: age greater than 50; Hunt and Hess grade 4 or 5; Fisher scale 3 or 4; aneurysm size greater than 10 mm; and posterior circulation aneurysm 25 mm or more.
Read more about this topic: Subarachnoid Hemorrhage