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Neuroradiology
Demonstration data

Spetzler-Martin AVM Grade

Grading of brain arteriovenous malformations to predict the risk of surgical resection.

The Spetzler-Martin scale grades cerebral arteriovenous malformations from I to V by summing points for nidus size, eloquence of adjacent brain, and pattern of venous drainage, predicting the risk of neurological morbidity from microsurgical resection.

🧮 Interactive Calculator

📐 Formula

Grade = size (1–3) + eloquence (0/1) + deep venous drainage (0/1)

When to Use

  • Pre-treatment assessment of a brain AVM on angiography, CT or MRI.
  • Estimating surgical resection risk and guiding treatment choice.
  • Standardised communication between neurosurgery, radiology and radiosurgery teams.

How It Works

  • Size: < 3 cm = 1, 3–6 cm = 2, > 6 cm = 3 points.
  • Eloquent location (sensorimotor, language, visual cortex, hypothalamus/thalamus, internal capsule, brainstem, cerebellar peduncles/nuclei): +1 point.
  • Deep venous drainage (any drainage through deep veins): +1 point.
  • Grade = sum of the three components, ranging from 1 to 5.

Interpreting the Result

  • Grade I–II — low surgical risk; generally favourable for microsurgical resection.
  • Grade III — intermediate risk; management is individualised.
  • Grade IV–V — high surgical morbidity; often managed conservatively or with staged/multimodal therapy.
  • A separate grade VI denotes an inoperable lesion in some schemes.

Limitations & Pitfalls

  • Predicts microsurgical risk, not rupture risk or radiosurgery outcome.
  • Does not include patient age, diffuseness or prior haemorrhage (addressed by the supplemented Lawton-Young grade).
  • Eloquence is defined categorically and can be subjective at borders.

References

  • Spetzler RF, Martin NA. A proposed grading system for arteriovenous malformations. J Neurosurg. 1986;65(4):476-483.
  • Lawton MT, Kim H, McCulloch CE, Mikhak B, Young WL. A supplementary grading scale for selecting patients with brain arteriovenous malformations for surgery. Neurosurgery. 2010;66(4):702-713.

⚕️ For clinical decision support only. Always verify calculations and apply clinical judgment.