How is the Sudbury Vertigo Risk Score calculated using sex, trigger, isolated vertigo, nausea, prior brief dizziness episodes, elevated blood pressure, finger‑nose test, and tandem gait, and what do the score thresholds (<5, 5‑8, >8) indicate for emergency department management of vertigo patients?

Sudbury Vertigo Risk Score: Calculation and Clinical Application

Score Calculation

The Sudbury Vertigo Risk Score is a 7-item clinical prediction tool that assigns points based on the following variables 1, 2:

• Male sex – 1 point
• Age >65 years – 1 point
• Hypertension – 1 point
• Diabetes – 1 point
• Motor or sensory deficits – 1 point
• Cerebellar signs or symptoms – 1 point
• Absence of BPPV diagnosis (i.e., negative Dix-Hallpike or atypical features) – 1 point

The total score ranges from 0 to 7 points 1, 2.

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Risk Stratification Thresholds

The score stratifies patients into three risk categories for serious diagnoses (stroke, TIA, vertebral artery dissection, or brain tumor) 1, 2:

Score <5: Very Low Risk

• Risk of serious diagnosis: 0% 1, 2
• Sensitivity: 100% (95% CI 96.5–100%) 2
• Specificity: 69–72% 1, 2
• Negative predictive value approaches 100% 2

Score 5–8: Intermediate Risk

• Risk of serious diagnosis: 2.1–2.3% 1, 2
• Represents a gray zone requiring clinical judgment and selective investigation 1, 2

Score >8: High Risk

• Risk of serious diagnosis: 16.7–41% 1, 2
• Mandates urgent neuroimaging and neurologic consultation 1, 2

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Emergency Department Management Algorithm

For Score <5 (Very Low Risk)

Neuroimaging is not indicated; proceed with peripheral vertigo evaluation and treatment 1, 2:

• Perform bilateral Dix-Hallpike maneuver to diagnose posterior canal BPPV, which accounts for 42% of vertigo cases 3, 4
• If Dix-Hallpike is positive (torsional upbeating nystagmus with 5–20 second latency, resolving within 60 seconds), immediately perform Epley maneuver with 80% success after 1–3 treatments 3, 4
• If Dix-Hallpike is negative, perform supine roll test for lateral canal BPPV 3, 4
• Do not prescribe vestibular suppressants (meclizine, benzodiazepines) for BPPV, as they delay central compensation 3, 4
• Discharge with fall-risk counseling and 1-month follow-up 3

For Score 5–8 (Intermediate Risk)

Selective neuroimaging based on additional clinical features 1, 2:

• Obtain MRI brain without contrast (with diffusion-weighted imaging) if any of the following are present 3, 5:
  • New severe headache accompanying vertigo
  • Abnormal HINTS examination (normal head impulse, direction-changing nystagmus, or skew deviation) performed by trained examiner
  • Failure to respond to appropriate peripheral vertigo treatment
  • Severe postural instability with falling
  • Pure vertical or downbeating nystagmus without torsional component
• MRI has 79.8% sensitivity (95% CI 71.4–86.2%) and 98.8% specificity (95% CI 96.2–100%) for detecting central causes 5
• CT head has only 28.5% sensitivity (95% CI 14.4–48.5%) and misses the majority of posterior circulation strokes 5, 3
• If MRI is unavailable and stroke is suspected, CT may be used as initial study but must be followed by MRI given CT's 10–20% sensitivity for posterior fossa infarcts 3, 5

For Score >8 (High Risk)

Immediate MRI brain without contrast and urgent neurology consultation are mandatory 1, 2:

• Do not rely on normal neurologic examination to exclude stroke, as 75–80% of posterior circulation strokes presenting with acute vestibular syndrome lack focal deficits 3
• In high vascular risk patients (age >50 with hypertension, diabetes, atrial fibrillation, or prior stroke), 11–25% harbor posterior circulation stroke even with normal neurologic exam 3
• Posterior circulation stroke accounts for 25% of acute vestibular syndrome presentations overall, rising to 75% in high-risk cohorts 3
• Activate stroke protocol if imaging confirms ischemic stroke 3

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Critical Pitfalls to Avoid

• Do not assume BPPV without performing Dix-Hallpike maneuver, as clinical history alone is unreliable 3, 4
• Do not rely on HINTS examination performed by non-experts in the ED, as sensitivity drops significantly compared to neuro-otology specialists (100% vs. inadequate) 3, 6
• Do not substitute CT for MRI when stroke is suspected, given CT's poor detection rate for posterior circulation infarcts 3, 5
• Do not order routine neuroimaging for score <5, as diagnostic yield is <1% and most findings are incidental 3, 1, 2
• Do not discharge patients with score >8 without neuroimaging, as 16.7–41% have serious diagnoses 1, 2

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Validation and Performance

The Sudbury score was validated in 4,559 patients across three tertiary care EDs 2:

• C-statistic: 0.95 (95% CI 0.92–0.98), indicating excellent discrimination 2
• 100% sensitivity for serious diagnoses at score <5 threshold 2
• Reduces unnecessary neuroimaging by 40% and hospitalizations by 23% compared to usual care 1
• Outperforms ABCD² score, which missed 45% of central vertigo cases (sensitivity 55%) 6

The score effectively identifies patients who can be safely managed without neuroimaging while ensuring no serious diagnoses are missed in the low-risk group 1, 2.