What is the significance of leukocytosis (elevated White Blood Cell (WBC) count), neutrophilia (high neutrophil percentage), and thrombocytosis (elevated platelet count) in a patient with sudden-onset severe vertigo?

Laboratory Findings in Sudden-Onset Severe Vertigo

Direct Interpretation of Your Laboratory Values

Your laboratory findings show a mild inflammatory response pattern that is consistent with peripheral vestibular disorders, particularly vestibular neuritis, but does not help distinguish between peripheral and central causes of vertigo. The elevated WBC (12.1), neutrophilia (81%), relative lymphopenia (12.4%), elevated ANC (9.8), and thrombocytosis (455) collectively suggest an inflammatory or infectious process 1, 2.

Clinical Significance of These Specific Values

Neutrophil-to-Lymphocyte Ratio (NLR)

• Your calculated NLR is approximately 6.5 (81%/12.4%), which falls into the moderate stress/inflammation range 2
• In vestibular neuritis specifically, patients typically show elevated WBC counts (mean ~10,500/mm³) with higher lymphocyte counts (mean ~5,000/mm³) and paradoxically lower NLR values (mean 0.9±0.2) 3
• Your pattern differs from typical vestibular neuritis, as you have neutrophil predominance rather than lymphocyte predominance 3
• Studies show that BPPV patients typically have higher NLR (mean 1.9±0.9) compared to vestibular neuritis patients, though your NLR is higher than both groups 3

White Blood Cell Count

• Your WBC of 12.1 is mildly elevated, suggesting an inflammatory process 1
• This elevation supports the inflammatory nature of peripheral vestibular disorders, where higher plasma inflammatory markers (including elevated WBC) confirm the inflammatory process 1
• However, one study found no statistically significant difference in inflammatory markers between peripheral vertigo patients and controls, suggesting these findings may not be diagnostically specific 4

Platelet Count

• Your platelet count of 455 represents mild thrombocytosis 2
• Elevated platelets can indicate acute inflammation or stress response 2
• The platelet-to-lymphocyte ratio (PLR) would be approximately 367 in your case, which is elevated 4

What These Labs DO NOT Tell You

Critical limitation: These laboratory findings cannot distinguish between peripheral vestibular disorders (vestibular neuritis, labyrinthitis) and central causes like posterior circulation stroke 5, 6. This is the most important clinical pitfall to avoid.

Why This Matters

• 75-80% of patients with acute vestibular syndrome from posterior circulation infarct have no focal neurologic deficits, making clinical examination unreliable 5, 6
• Laboratory markers of inflammation do not exclude stroke 5
• The detection rate of posterior circulation infarct in acute vestibular syndrome is 11-25%, rising to 75% in high vascular risk cohorts 5, 6

Immediate Clinical Action Required

Red Flag Assessment

You must immediately assess for these features that mandate urgent MRI brain without contrast 6, 7:

• Focal neurological deficits (speech difficulties, weakness, numbness, visual disturbances)
• Inability to stand or walk
• New severe headache (particularly occipital)
• Sudden unilateral hearing loss
• Downbeating or direction-changing nystagmus
• Vascular risk factors: age >50, hypertension, diabetes, atrial fibrillation, prior stroke 6

HINTS Examination

If you have access to a specially trained examiner, the HINTS examination (Head Impulse, Nystagmus, Test of Skew) has 100% sensitivity for detecting posterior circulation stroke versus 46% for early MRI 6. However, when performed by non-experts, results are unreliable 6.

HINTS findings suggesting central (stroke) cause 6:

• Normal head impulse test (concerning for central cause)
• Direction-changing or vertical nystagmus
• Present skew deviation

Imaging Decision Algorithm

If ANY red flags present OR high vascular risk: Obtain MRI brain without contrast immediately 6. Do not rely on CT, as it has <1% diagnostic yield and misses most posterior circulation infarcts 6.

If NO red flags AND trained HINTS examiner available: HINTS examination can safely exclude stroke if consistent with peripheral vertigo 6.

If NO red flags but NO trained HINTS examiner: Consider MRI brain without contrast given the 11-25% stroke rate in acute vestibular syndrome 5, 6.

Most Likely Diagnosis Based on Lab Pattern

Your inflammatory pattern (elevated WBC, neutrophilia, thrombocytosis) is most consistent with vestibular neuritis or labyrinthitis 1, 2, which are thought to result from viral infection causing inflammation and demyelination of the vestibular nerve 1. The inflammatory nature is confirmed by elevated inflammatory markers 1.

However, this laboratory pattern does not exclude stroke and should never be used alone to make this determination 5, 6. The clinical examination, HINTS testing (if available), and imaging (if indicated) are far more important than these laboratory values for distinguishing peripheral from central causes.

Common Pitfalls to Avoid

• Never assume normal labs exclude stroke - inflammatory markers are irrelevant to stroke diagnosis 5, 6
• Never assume normal neurologic exam excludes stroke - 75-80% of posterior circulation strokes present without focal deficits 5, 6
• Never order CT instead of MRI when stroke is suspected - CT misses most posterior circulation infarcts 6
• Never rely on patient's description of "spinning" versus "lightheadedness" - focus on timing, triggers, and red flags instead 6