Spetzler-Martin Grade Calculator

Spetzler-Martin Grade Calculator for Neurology. Grades I-V describe anatomical features relevant to surgery, not a universal treatment algorithm. The AHA/ASA statement discusses grading alongside treatment context: https://www.ahajournals.org/doi/10.1161/STR.0000000000000134

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

Size <3 cm gives 1, 3-6 cm gives 2, and >6 cm gives 3. Add one for eloquent location and one for any deep drainage. Original model: https://pubmed.ncbi.nlm.nih.gov/3760956/ . A primary surgical cohort also distinguishes <3 from 3-6 cm lesions and discusses additional risk factors: https://pubmed.ncbi.nlm.nih.gov/20190666/

When to use this calculator

Support discussion of brain AVM microsurgical risk after appropriate anatomical assessment. Do not use an associated hematoma or draining-vein diameter as nidus size.

Inputs used

  • Specialist-characterized brain AVM anatomy
  • Maximum nidus diameter in cm
  • Adjacent eloquent brain: present, absent or unassessable
  • Any deep venous drainage: present, absent or unassessable

Clinical interpretation

Grades I-V describe anatomical features relevant to surgery, not a universal treatment algorithm. The AHA/ASA statement discusses grading alongside treatment context: https://www.ahajournals.org/doi/10.1161/STR.0000000000000134

Worked example

A nidus exactly 6 cm across scores 2 for size. Adjacent eloquent tissue and mixed superficial/deep drainage add 1 each: grade IV. At 6.01 cm the same findings give V.

Limitations and safety notes

Age, rupture history, diffuseness, associated aneurysms and treatment expertise are not encoded. The original descriptive grade VI is not an additive score. No hemorrhage probability or preferred procedure is generated.

Frequently asked questions

Does mixed venous drainage count as deep?

Yes. Any deep drainage contributes one point; only exclusively superficial drainage contributes zero.

References

  • Spetzler and Martin. Original AVM grading, 1986: https://pubmed.ncbi.nlm.nih.gov/3760956/
  • AHA/ASA brain AVM scientific statement, 2017; treatment context: https://www.ahajournals.org/doi/10.1161/STR.0000000000000134
  • Lawton et al. Primary surgical cohort, 2010; size categories and factors beyond Spetzler-Martin: https://pubmed.ncbi.nlm.nih.gov/20190666/

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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