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PubMed This is a summary of 15 peer-reviewed journal articles Updated
Neurology

Understanding Your Scans & The Spetzler-Martin Grading Scale

At a Glance

The Spetzler-Martin Grading Scale helps doctors determine the surgical risk of a brain AVM based on its size, location in critical brain areas (eloquence), and venous drainage. Digital Subtraction Angiography (DSA) is the gold standard scan used to map these details and guide treatment decisions.

Navigating the technical language of brain imaging can feel like learning a new language. To determine the safest path forward, your care team uses specific grading scales and high-resolution scans to “map” the architecture of your AVM [1][2].

The Spetzler-Martin Grading Scale

The Spetzler-Martin (SM) Grade is the most widely used system to estimate the risk of surgically removing an AVM [3]. It assigns points (1 to 5) based on three physical characteristics:

  • Size: Points are given based on the largest diameter of the nidus (the central tangle).
    • Small AVMs (under 3 cm): 1 point [3]
    • Medium AVMs (3 to 6 cm): 2 points [3]
    • Large AVMs (over 6 cm): 3 points [3]
  • Eloquence: This refers to whether the AVM is located in “eloquent” brain tissue. Eloquent cortex includes areas critical for neurological functions like speaking, moving your limbs, or seeing [4]. If an AVM is in an eloquent area, it gets 1 point because surgery there carries a higher risk of causing a permanent deficit [5][6].
  • Venous Drainage: If the blood drains only through superficial veins (on the surface), it gets 0 points. If any blood drains through deep venous drainage (veins deep within the brain), it gets 1 point. Deep drainage is more complex for surgeons to manage [3][7].

The Grading Score:

  • Grades I–II: Generally considered lower risk for surgery [8].
  • Grade III: An “intermediate” group where doctors must very carefully weigh the pros and cons [2].
  • Grades IV–V: High-risk lesions where conservative (non-surgical) management is often preferred [9].

The Supplemented Scale

Doctors may also use the Supplemented Spetzler-Martin (Supp-SM) scale [2]. This adds points for your age, whether the AVM has previously bled (rupture), and whether the nidus is compact or “diffuse” (spread out). This supplemented score helps surgeons more accurately predict how well a patient will recover after treatment [2][10].

Understanding the Imaging “Gold Standard”

You will likely undergo several types of scans to get a complete picture of your AVM:

  1. MRI / MRA: Excellent for showing the AVM’s relationship to the surrounding brain tissue and identifying “eloquence” [11][4].
  2. CT / CTA: Often the first scan used in an emergency to look for blood (hemorrhage) and the basic structure of the vessels [12].
  3. Digital Subtraction Angiography (DSA): This is the gold standard. A thin tube (catheter) is threaded through an artery (usually in the leg or wrist) up to the brain. A special dye is injected while X-rays are taken. Unlike a regular MRI, a DSA shows the blood moving in real-time, allowing doctors to see exactly how fast the blood is shunting and if there are hidden “weak spots” like aneurysms [13][14].

Your Radiology Report Checklist

When reviewing your imaging reports, ensure the following details are clearly documented. If they aren’t, ask your specialist for clarification:

  • [ ] Nidus Size: Measured in centimeters (cm) [3].
  • [ ] Location: Which lobe of the brain is it in? Is it in an eloquent area? [4]
  • [ ] Venous Drainage: Is it “superficial,” “deep,” or “mixed”? [7]
  • [ ] Associated Aneurysms: Are there weak bulges on the feeding arteries? [15]
  • [ ] Hemorrhage: Is there evidence of a current or old bleed (hemosiderin)? [2]
  • [ ] Nidus Morphology: Is the tangle “compact” (one tight ball) or “diffuse” (vessels mixed with healthy brain)? [2]

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Common questions in this guide

What is the Spetzler-Martin Grading Scale for brain AVMs?
The Spetzler-Martin Grading Scale is a system used to estimate the risk of surgically removing a brain AVM. It assigns a score from 1 to 5 based on three main factors: the size of the AVM, whether it is located in eloquent brain tissue, and if it has deep venous drainage.
What does eloquent brain tissue mean on my MRI report?
Eloquent cortex refers to areas of the brain that are critical for important functions like speaking, seeing, or moving your limbs. If your AVM is located in an eloquent area, surgery carries a higher risk of causing a permanent neurological deficit.
Why is a DSA (Digital Subtraction Angiography) necessary?
A DSA, or angiogram, is considered the gold standard because it allows doctors to see blood moving through the brain's vessels in real-time. Unlike a standard MRI, it shows exactly how fast blood is flowing and can identify hidden weak spots, such as aneurysms on the feeding arteries.
What is the nidus of a brain AVM?
The nidus is the central tangle of abnormal blood vessels that make up the arteriovenous malformation. Your radiology report should measure the largest diameter of the nidus in centimeters, as this size directly affects your Spetzler-Martin grade.
What does deep venous drainage mean?
Deep venous drainage means that the blood from your AVM drains through veins located deep within the brain, rather than just superficial veins on the surface. This type of drainage makes the AVM more complex for surgeons to manage and adds a point to your Spetzler-Martin score.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is my Spetzler-Martin grade and my Supplemented Spetzler-Martin score?
  2. 2.Which specific areas of 'eloquence' is my AVM touching or located within?
  3. 3.Does my AVM have 'deep venous drainage' or 'venous stenosis' that increases my risk?
  4. 4.Are there any 'flow-related' aneurysms on the feeding arteries?
  5. 5.When do we need to perform a DSA (angiogram) to get a more detailed look?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (15)
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    Critical review of brain AVM surgery, surgical results and natural history in 2017.

    Morgan MK, Davidson AS, Assaad NNA, Stoodley MA

    Acta neurochirurgica 2017; (159(8)):1457-1478 doi:10.1007/s00701-017-3217-x.

    PMID: 28555270
  2. 2

    Spetzler-Martin Grade III Arteriovenous Malformations: A Comparison of Modified and Supplemented Spetzler-Martin Grading Systems.

    Frisoli FA, Catapano JS, Farhadi DS, et al.

    Neurosurgery 2021; (88(6)):1103-1110 doi:10.1093/neuros/nyab020.

    PMID: 33582762
  3. 3

    Influence of preoperative embolisation on resection of brain arteriovenous malformations: cohort study.

    Lee SH, Loan JJ, Downer J, et al.

    Acta neurochirurgica 2024; (166(1)):345 doi:10.1007/s00701-024-06234-4.

    PMID: 39167231
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    Presurgical Functional Mapping with Magnetoencephalography.

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    Neuroimaging clinics of North America 2020; (30(2)):159-174 doi:10.1016/j.nic.2020.02.005.

    PMID: 32336404
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    A study of pediatric cerebral arteriovenous malformations: clinical presentation, radiological features, and long-term functional and educational outcomes with predictors of sustained neurological deficits.

    Ravindra VM, Bollo RJ, Eli IM, et al.

    Journal of neurosurgery. Pediatrics 2019; (24(1)):1-8.

    PMID: 30952115
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    Feasibility of awake craniotomy for brain arteriovenous malformations: A scoping review.

    Tariq R, Siddiqui UA, Bajwa MH, et al.

    World neurosurgery: X 2024; (22()):100321 doi:10.1016/j.wnsx.2024.100321.

    PMID: 38440377
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    Are hemodynamics responsible for inflammatory changes in venous vessel walls? A quantitative study of wall-enhancing intracranial arteriovenous malformation draining veins.

    Stahl J, McGuire LS, Rizko M, et al.

    Journal of neurosurgery 2024; (141(2)):333-342 doi:10.3171/2024.1.JNS232625.

    PMID: 38552234
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    More II It than Meets the Eye: Outcomes After Single-Fraction Stereotactic Radiosurgery in a Case Series of Low-Grade Arteriovenous Malformations.

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    Operative neurosurgery (Hagerstown, Md.) 2020; (18(2)):136-144 doi:10.1093/ons/opz153.

    PMID: 31250901
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    Stereotactic Radiosurgery for Intermediate (III) or High (IV-V) Spetzler-Martin Grade Arteriovenous Malformations: International Stereotactic Radiosurgery Society Practice Guideline.

    Graffeo CS, Kotecha R, Sahgal A, et al.

    Neurosurgery 2025; (96(2)):298-307 doi:10.1227/neu.0000000000003102.

    PMID: 38989995
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    The Application of the Novel Grading Scale (Lawton-Young Grading System) to Predict the Outcome of Brain Arteriovenous Malformation.

    Hafez A, Koroknay-Pál P, Oulasvirta E, et al.

    Neurosurgery 2019; (84(2)):529-536 doi:10.1093/neuros/nyy153.

    PMID: 29733392
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    Conventional digital subtractional vs non-invasive MR angiography in the assessment of brain arteriovenous malformation.

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    Clinical neurology and neurosurgery 2018; (169()):29-33 doi:10.1016/j.clineuro.2018.03.022.

    PMID: 29604508
  12. 12

    Co-occurrence of cerebral arteriovenous malformation and jugular bulb dehiscence as the etiology of pulsatile tinnitus: A case report.

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    Radiology case reports 2026; (21(1)):310-313 doi:10.1016/j.radcr.2025.09.028.

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    Validation of cerebral arteriovenous malformation hemodynamics assessed by DSA using quantitative magnetic resonance angiography: preliminary study.

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    Journal of neurointerventional surgery 2018; (10(2)):156-161 doi:10.1136/neurintsurg-2017-012991.

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    Quantitative evaluation of arteriovenous malformation hemodynamic changes after endovascular treatment using parametric color coding: A case series study.

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    Early Rebleeding after Brain Arteriovenous Malformation Rupture, Clinical Impact and Predictive Factors: A Monocentric Retrospective Cohort Study.

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This page explains brain AVM grading and imaging terminology for educational purposes only. Always discuss your specific scan results and Spetzler-Martin grade directly with your neurosurgeon or care team.

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