Spetzler-Martin Scale for Grading Arteriovenous Malformations (AVM) of the Brain

 

Point Assignment	Finding	Points
size of AVM	small ( < 3 cm)	1
	medium (3-6 cm)	2
	large (> 6 cm)	3
eloquence of adjacent brain	non-eloquent	0
	eloquent	1
pattern of venous drainage	superficial only	0
	deep	1

 

Eloquence of adjacent brain:

(1) Eloquent brain areas are those associated with a readily identified neurological function and which are associated with a disabling neurological deficit when injured.

(2) Examples of eloquent brain areas: sensorimotor cortex, language cortex, visual cortex, hypothalamus, thalamus, internal capsule, brain stem, cerebellar peduncles, deep cerebellar nuclei.

(3) Noneloquent brain areas are those with subtle neurological function or which are not associated with disabling neurological deficits when injured.

(4) Examples of noneloquent brain areas are the anterior portion of the frontal lobes, the anterior portion of the temporal lobes and the cerebellar cortex.

 

Pattern of venous drainage on angiography:

(1) superficial if all drainage from the AVM is through the cortical venous system

(2) deep if any or all of the drainage is through the deep veins such as internal cerebral veins, basal veins or precentral cerebellar vein

 

grade of AVM =

= (points for AVM size) + (points for eloquence) + (points for venous drainage pattern)

 

Interpretation

 

Possible grades for surgical candidates: 1 through 5

Grade 6: surgically inoperable

 

Grade	Number of Patterns	Patterns
1	1	(1,0,0)
2	3	(2,0,0); (2,0,1); (1,1,0)
3	4	(3,0,0); (2,0,1); (2,1,0); (1,1,1)
4	3	(3,0,1); (3,1,0); (2,1,1)
5	1	(3,1,1)

 

Deficits from surgery:

(1) Minor: very mild increase in brainstem deficit, temporary increase in visual field deficit, temporary increase in aphasia and weakness, mild increase in aphasia only detectable with rapid speech, temporary mild increase in weakness, increase in trigeminal nerve deficit, mild temporary increase in hemiparesis, mild residual ataxia, or temporary mild dysphasia

(2) Major: hemiparesis, increase in aphasia, homonymous hemianopsia, severe neurological deficit with major aphasia and hemiparesis

 

Grade	Likelihood of complications from surgery
1	very low for minor and major deficits after surgery
2	low for minor and very low for major deficits
3	intermediate for minor and low for major deficits
4	significant numbers of minor and intermediate for major deficits
5	significant numbers of minor and major deficits