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The neuro calculations provides neuroanatomy, neurophysiology, and neurosurgical calculations based upon patient demographic information provided in the fields above. Some calculations require additional patient data, for which fields are provided within the calculation. As with all clinical decision support tools, ultimately use clinical judgement when considering these results.

• Some calculations may have important additional information which can be shown using the question mark icon

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Use the discussion page to leave feedback about the calculator. To contribute more substantially, see the calculators guide to learn about the process to get developer access.

The neuro calculations calculator is powered by the patients and neuro modules.

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Brain mass

1370 g

This calculation will give a more precise estimate of brain mass if age and/or sex are provided.

1. Dekaban AS. Changes in brain weights during the span of human life: relation of brain weights to body heights and body weights. Ann Neurol. 1978 Oct;4(4):345-56. doi: 10.1002/ana.410040410. PMID: 727739.

Cerebral blood volume

55 mL

4 mL per 100g of brain mass

1. Tameem A, Krovvidi H, Cerebral physiology, Continuing Education in Anaesthesia Critical Care & Pain, Volume 13, Issue 4, August 2013, Pages 113–118, https://doi.org/10.1093/bjaceaccp/mkt001

Cerebral metabolic rate (O₂)

Temperature

°C°F

41 mL/min

• 3 mL O₂/min per 100g of brain mass
• If temperature is provided, adjusts estimate using 7% change in CMR for every 1 °C change in temperature

1. Tameem A, Krovvidi H, Cerebral physiology, Continuing Education in Anaesthesia Critical Care & Pain, Volume 13, Issue 4, August 2013, Pages 113–118, https://doi.org/10.1093/bjaceaccp/mkt001

Cerebral metabolic rate (Glucose)

68.5 mg/min

• 5 mg glucose/min per 100g of brain mass
• 7% change in CMR for every 1 °C change in temperature

1. Tameem A, Krovvidi H, Cerebral physiology, Continuing Education in Anaesthesia Critical Care & Pain, Volume 13, Issue 4, August 2013, Pages 113–118, https://doi.org/10.1093/bjaceaccp/mkt001

Cerebral blood flow

PaCO₂

mmHg

685 mL/min

• 50 mL/min per 100g of brain mass.
• Every mmHg in PaCO2 changes CBF by 1.5 mL/min per 100g of brain mass.
• Cerebral blood flow and cerebral metabolic rate are coupled. Factors that alter CMR (e.g. temperature) will proportionally alter CBF.

1. Tameem A, Krovvidi H, Cerebral physiology, Continuing Education in Anaesthesia Critical Care & Pain, Volume 13, Issue 4, August 2013, Pages 113–118, https://doi.org/10.1093/bjaceaccp/mkt001
2. Brian JE Jr. Carbon dioxide and the cerebral circulation. Anesthesiology. 1998 May;88(5):1365-86. doi: 10.1097/00000542-199805000-00029. PMID: 9605698.

Glasgow Coma Scale

Eye responseNot testableNo eye openingTo painTo voiceSpontaneous

Verbal responseNot testableMakes no soundsIncomprehensible soundsInappropriate wordsConfusedOriented

Motor responseNot testableNo movementsExtension to painFlexion to painWithdrawal from painLocalizes PainObeys commands

Glasgow coma score:

Cannot be calculated because one or more components are not testable

Glasgow coma scale:

E(NT) V(NT) M(NT)

1. Teasdale G, Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974 Jul 13;2(7872):81-4. doi: 10.1016/s0140-6736(74)91639-0. PMID: 4136544.

Spetlzer-Martin AVM grading scale

AVM Size

cm

Eloquence of adjacent brainNon-eloquentEloquent

Venous drainageSuperficial veins onlyDeep veins

I (low-to-moderate risk)

The Spetzler-Martin AVM grading system predicts the morbidity/mortality risk of surgery using angiographic features

• Size of nidus
  • 0: Small (<3 cm)
  • 1: Medium (3-6 cm)
  • 2: Large (>6 cm)
• Eloquence of adjacent brain area
  • 0: Non-eloquent
  • 1: Eloquent
• Venous drainage
  • 0: Superficial veins only
  • 1: Deep veins

1. Spetzler RF, Martin NA. A proposed grading system for arteriovenous malformations. J Neurosurg. 1986 Oct;65(4):476-83. doi: 10.3171/jns.1986.65.4.0476. PMID: 3760956.

Supplemental AVM grading scale

Ruptured presentationUnrupturedRuptured

Nidus compactnessCompactDiffuse

Age required

The Supplemental AVM grading system provides additional surgical risk stratification in addition to the Spetzler-Martin grade.

• Age
  • 1: <20 yo
  • 2: 20-40 yo
  • 3: >40 yo
• Ruptured presentation
  • 0: Unruptured
  • 1: Ruptured
• Nidus compactness
  • 0: Compact
  • 1: Diffuse

1. 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 Apr;66(4):702-13; discussion 713. doi: 10.1227/01.NEU.0000367555.16733.E1. PMID: 20190666; PMCID: PMC2847513.