Arteriovenous malformations (AVMs) of the brain may be graded based on key features. The grade is associated with the likelihood of complications following surgical resection of the lesion. Grade 1 lesions are small and superficial with little risk from resection, whereas Grade 5 lesions are large, deep, involving critical areas of the brain and associated with significant risk from surgery.
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 |
Specialty: Neurology
ICD-10: ,