Arteriovenous Malformation Scores

Table.  Predictive grading systems for procedural risk in the endovascular treatment of brain AVMs.Capture


Buffalo score best predicts procedural risks, although predictive value is modest (AUC ~0.7).



Pulli, B., Stapleton, C., Walcott, B., Koch, M., Raymond, S., & Leslie-Mazwi, T. et al. (2019). Comparison of predictive grading systems for procedural risk in endovascular treatment of brain arteriovenous malformations: analysis of 104 consecutive patients. Journal Of Neurosurgery, 1-9. doi: 10.3171/2019.4.jns19266


ABCD2 Score



Table: ABCD2 Score


TIA Prognosis and Key Mx Considerations by National Stroke Association

ABCD2 Score:

  • Discharge low risk scores (ABCD 0-3)
    • outpatient work-up within 1-2 days (alternate option: admit for work-up)
      • carotid imaging (US, CTA, MRA)
      • Consider TTE; if high suspicion for cardioembolic source / bilateral infarcts, obtain TEE
      • Consider 30-d ambulatory cardiac monitor to detect cryptogenic Afib
    • smoking cessation
      • Start antiplatelet therapy:
        • ASA 81mg/day or
        • Clopidogrel 75mg/day or
        • ASA 25mg/ER dipyridamole 200mg BID
      • start high-intensity statins
        • Atorvastatin 40-80mg/d or
        • Rosuvastatin 20-40mg/day
      • *consider moderate intensity statins if >75y/o
        • Atorvastatin 10-20mg/d or
        • Rosuvastatin 5-10mg/d or
        • Simvastatin 20-40mg/d or
        • Pravastatin 40-80mg/d
      • Consider OAC or LMWH if rhythm shows atrial fibrillation – calculate CHADSVASC and HAS BLED score to guide therapy

    Admit high risk TIAs (ABCD2 scores >3)

    • Admit to hospital
    • Permissive hypertension (up to 220/120mm Hg) and gradually lower over 24-48h

Reference: (2017). [online] Available at: [Accessed 31 Jul. 2017].

Gross, Hartmut, and Noah Grose. 2017. “Emergency Neurological Life Support: Acute Ischemic Stroke”. Neurocritical Care 27 (S1): 102-115. doi:10.1007/s12028-017-0449-9.

SETScore for Early Tracheostomy in Stroke


**APS acute physiology score, LIS lung injury score


  • initially an in-house screening tool for tracheostomy prediction
  • performed within 1st 24 hours after admission – use worst value in the first 24 hours
  • Dysphagia either
    • reported from a transferring neurological department or
    • observed by clinical signs on admission
      • non-successful swallowing test
      • impaired saliva handling
      • loss/reduction of gag reflex
    • if already intubated on admission, scored with “0”
  • (Neuro)surgical intervention
    • decompressive surgery, hematoma removal, non-cranial major surgery
    • NOTE EVD or probe placement, thrombectomy, angioplasty for vasospasm or coiling
  • Diffuse lesion = a multilocular or widespread affection of brain (i.e. SAH, brain edema, multiple infarcts, hematomas)
  • hydrocephalus = distension of ventricles requiring EVD
  • total sum ranges between 3 and 37

Previously used (with score of >10) to screen for eligibility to be included in pilot trial of SETPOINT study for early tracheostomy (within 3 days) to standard regimen (late tracheostomy between day7 and day14).




Schönenberger, Silvia et al. “The Setscore To Predict Tracheostomy Need In Cerebrovascular Neurocritical Care Patients”. Neurocritical Care 25.1 (2016): 94-104.


The Buffalo Score (AVM)

The Buffalo Score is a new grading system for the endovascular treatment of cerebral AVMs.  It is a 5-point system, and higher scores is associated with higher complication rates.  This new score was created because components of the Spetzler Martin Grading scale, while useful for determining suitability of surgical treatment of cerebral AVMs, may not be relevant in determining suitability for endovascular treatment.

For example, the diameter and number of arterial pedicles supplying the AVM nidus is an important factors to consider in endovascular intervention, since smaller vessels are more prone to injury with catheterization, and a greater number of arterial pedicles produces more risk with each embolization.  The actual size of the AVM nidus and venous drainage pattern is important when considering surgical resection, but is less important during endovascular embolization.

Points for Buffalo Score:

  • number of arterial pedicles
    • 1 point for 1–2 pedicles
    • 2 points for 3–4
    • 3 points greater than 5
  • arterial pedicle diameter
    • 1 point for less than 1 mm
    • 0 points for more than 1 mm
  • eloquence of the location
    • 1 point for eloquent location
    • 0 point for non-eloquent location




Buffalo System Vs. Spetzler Martin Grading System:


*arterial pedicles for Buffalo and draining veins for Spetzler Martin (black lines); nidus (black shading);  deep drainage (dashed lines)

  • Buffalo system = # arterial pedicles (N), diameter of pedicles (D), and eloquence (E)
  • Spetzler–Martin system = venous drainage (V), size (S), eloquence (E)



  1. Measurement of arterial pedicle diameter is made at a distal segment of the arterial pedicle, within 1 cm of the AVM nidus.
  2. Eloquent location is determined based on the nidus location and is defined according to the grading system of Spetzler-Martin.
  3. Any portion of AVM nidus located within motor or sensory cortex, language and vision, and deep eloquent areas (hypothalamus, thalamus, brainstem, cerebellar peduncles) is considered eloquent in location.
  4. This system has not been applied or validated yet.



Levy, EladI et al. “A Proposed Grading System For Endovascular Treatment Of Cerebral Arteriovenous Malformations: Buffalo Score”. Surgical Neurology International 6.1 (2015): 3.


CHESS (Chronic Hydrocephalus Ensuing from SAH Score)

The European Journal of Neurology recently published a risk score that allows early estimation of the probability for shunt dependency after subarachnoid hemorrhage. CHESS stands for Chronic Hydrocephalus Ensuing from SAH Score.  This score can be helpful in deciding whether a permanent CSF diversion is needed in post-hemorrhage hydrocephalus (PHH).

Inclusion criteria for the study:

  1. admission and treatment of ruptured aneurysm within 48 hours post-ictus
  2. patient survives up to the time of decision-making for shunt placement


Baseline Characteristics:


PHH was divided into 3 stages:

  1. acute (0-3 days post-SAH)
  2. subacute (4-13 days)
  3. chronic (>=14 days)


All patients with acute PHH underwent CSF diversion via EVD or lumbar drainage.  Continuous drianage was maintained for at least 7 days.  Patients who developed subacute PHH were treated with serial lumbar punctures.

The drain (EVD or lumbar drain) was challenged starting the second week of SAH in the absence of clinical contraindications (ICP issues or infection).  Drain was closed for 48 hours with CT scans performed before and after clamping.

Patients considered to fail EVD/LD challenge if:

  1. they deteriorate neurologically and/or they have increased headaches that improve with unclamping the drain
  2.  sustained ICP increase >20 cm H20
  3. radiographic evidence of increased ventricular size compared to baseline CT (CT prior to clamping)

Shunt placement was performed after two unsuccessful clamping trials.





The  following independent risk factors were identified and included in the CHESS:

  1. Hunt and Hess grade ≥IV (1 point, OR = 2.65)
  2. aneurysm in posterior circulation (1 point, OR = 2.37)
  3. (+) IVH on initial CT (1 point, OR = 2.41)
  4. (+) acute PHH (4 points, OR = 9.36)
  5. early cerebral infarction on follow-up CT scan (1 point, OR = 2.29)


The ROC curve between the CHESS and shunt rates showed a significant cutoff at 6 points.

  1. CHESS score ≥6 = 6.74-fold higher risk for shunt dependency (P < 0.0001)
  2. CHESS score <6 points showed NPV of 84.9%.
  3. CHESS <2 points showed NPV of 98.5%



  1. avoid unnecessary prolonged EVD/LD weaning (and reduce catheter-related meningitis)
  2. reduce readmission rates (for delayed shunt placement)

Based on this score, patients can be stratified into:

  1. high risk – score of 6-8
  2. moderate risk – 2-5
  3. low risk – 0-1

A shunt-restrictive policy as well as an early transfer to rehabilitation can be considered in SAH patients with low CHESS scores.



Jabbarli, R. et al. “The CHESS Score: A Simple Tool For Early Prediction Of Shunt Dependency After Aneurysmal Subarachnoid Hemorrhage”. Eur J Neurol (2016).

Modified Ramsay Scale

The Modified Ramsay Scale:

  • first scoring system for evaluating sedation in mechanically ventilated patients
  • four levels of sedation (3-6) and one level of agitation (1)
  • lack of scientific validation, but used in many ICUs




Marino, Paul L, Kenneth M Sutin, and Paul L Marino. The Little ICU Book Of Facts And Formulas. Philadelphia: Wolter Kluwer Health/Lippincott Williams & Wilkins, 2009. Print.