This poster was originally presented at the RANZCR Annual Scientific Meeting 2011, October 6-9, in Melbourne/AU.
Congress:
RANZCR ASM 2011
Keywords:
Interventional vascular, Neuroradiology brain, Catheter arteriography, CT, Aneurysms, Haemorrhage
Authors:
A. Lane, N. Stewart, L. Jones, A. Coulthard; Brisbane/AU
DOI:
10.1594/ranzcr2011/R-0149
Purpose
Non-traumatic subarachnoid haemorrhage (SAH) is caused by the rupture of an intracranial aneurysm in 85% of cases(1) and cerebral vasospasm is the leading cause of death and disability in patients with aneurysmal SAH (aSAH) (2).
Despite much research having focused on this potentially devastating complication,
it is still incompletely understood.
Grading scales for SAH abound,
and include :
- Fisher scale
- Modified Fisher scale
- World Federation of Neurosurgeons scale (WFNS)
- Hunt and Hess scale
- Hijdra sum score
- Glasgow Coma Scale
The Fisher scale (see Table 1):
- is a radiologic scale designed to predict the likelihood of vasospasm after aSAH
- was developed by Fisher et al in 1980 based on a study involving a cohort of 47 patients(3)
- associates thickness of subarachnoid blood and intracerebral or intraventricular blood with risk of vasospasm
- was subsequently validated in a prospective study by Kistler et al in 1983(4)
- identified weaknesses include the lack of consideration of clot density and clearance rates and lack of distinction between intracerebral and intraventricular haemorrhage(5-7),
and modifications to the scale have been suggested(6,
8)
- currently remains the strongest known determinant of risk of developing cerebral vasospasm after aSAH(3,
4,
9)
Table 1: The Fisher scale
Fisher score
|
CT finding
|
1
|
No blood detected
|
2
|
Diffuse deposition or thin layer with all vertical layers of blood (interhemispheric fissue,
insular cistern,
ambient cistern) < 1mm thick
|
3
|
Localised clots and or vertical layers of blood 1mm or greater in thickness
|
4
|
Any thickness of subarachnoid blood,
with intracerebral or intraventricular clots
|
The WFNS scale (see Table 2):
- is a clinically oriented grading system,
incorporating GCS and presence of focal motor deficit
- was developed in 1988 by the World Federation of Neurological Surgeons Committee for the purposes of estimating patient prognosis,
quantifying a change in status over time,
and to standardise evaluation of treatment(10)
- validity as a predictor of outcome was confirmed in a large study of around 3500 patients(11),
however not all investigators have been able to identify such a relationship(12,
13)
- was used in a study by Dupont et al investigating the relationship between a number of scales and vasospasm,
and found a WFNS grade of 4 or 5 conferred an increased risk(14)
- has not been found,
thus far,
to be reliable for prediction of vasospasm
Table 2: WFNS scale
WFNS score
|
GCS Score
|
Motor Deficit
|
1
|
15
|
Absent
|
2
|
13-14
|
Absent
|
3
|
13-14
|
Present
|
4
|
7-12
|
Present or absent
|
5
|
3-6
|
Present or absent
|
This study seeks an association between Fisher Grade and WFNS Grade and the risk of developing vasospasm after aneurysmal SAH treated by endovascular coiling.