What are the red flags to look for when evaluating a patient with dizziness?

Red Flags in Dizziness Evaluation

When evaluating a patient with dizziness, immediately assess for focal neurological deficits, sudden hearing loss, inability to stand or walk, new severe headache, downbeating or central nystagmus patterns, and failure to respond to appropriate vestibular treatments—these red flags mandate urgent neuroimaging and neurologic consultation. 1, 2

Critical Warning Signs Requiring Immediate Action

Neurological Red Flags

• Focal neurological deficits including diplopia, dysarthria, facial numbness, limb weakness, or sensory changes suggest posterior circulation stroke or other central pathology 3, 1, 2
• Inability to stand or walk independently indicates severe vestibular dysfunction or central lesion 1, 2
• New severe headache accompanying dizziness mandates immediate imaging and neurologic consultation, as this may indicate hemorrhage, dissection, or posterior fossa pathology 2

Otologic Red Flags

• Sudden unilateral hearing loss with vertigo raises concern for labyrinthitis, stroke affecting the anterior inferior cerebellar artery territory, or other serious pathology 3, 1, 2
• Unilateral or pulsatile tinnitus warrants neuroimaging to exclude cerebellopontine angle tumors (including vestibular schwannomas) or vascular malformations 3, 2

Examination Red Flags

• Downbeating nystagmus or other central nystagmus patterns (direction-changing without positional trigger, purely vertical, purely torsional) indicate brainstem or cerebellar pathology 1, 2
• Abnormal HINTS examination (normal head impulse test, direction-changing nystagmus, or skew deviation) in acute vestibular syndrome has 100% sensitivity for stroke when performed by trained examiners 2
• Loss of consciousness is never a symptom of peripheral vestibular disorders like Ménière's disease and suggests cardiac, neurologic, or systemic causes 3

Important Clinical Context

The 75-80% Rule

A critical pitfall to avoid: 75-80% of patients with acute vestibular syndrome from posterior circulation infarction have NO focal neurologic deficits on standard examination. 2 This means a "normal" neurologic exam does not exclude stroke—you must rely on timing, triggers, and specialized bedside tests like HINTS.

Duration and Timing Matter

• Acute persistent vertigo lasting days to weeks (acute vestibular syndrome) carries the highest stroke risk and requires differentiation between vestibular neuritis and posterior circulation stroke 3, 2, 4
• Brief episodes (seconds to minutes) triggered by head position typically indicate benign paroxysmal positional vertigo, but atypical Dix-Hallpike responses increase risk of central pathology 3, 2

High-Risk Patient Populations

• Patients with vascular risk factors (hypertension, diabetes, smoking, atrial fibrillation, prior stroke) presenting with acute vestibular syndrome require MRI even with reassuring bedside examination 2
• Elderly patients may not manifest classic "spinning" vertigo even with serious pathology, instead describing vague dizziness or vestibular disturbance 3

Red Flags by Clinical Syndrome

For Acute Vestibular Syndrome (Continuous Symptoms Days to Weeks)

• Normal head impulse test in a patient with acute vertigo and nystagmus suggests central cause 2
• Any focal neurologic signs 2
• Severe truncal ataxia out of proportion to subjective symptoms 4

For Episodic Vestibular Syndromes

• Failure to respond to appropriate treatment (e.g., canalith repositioning for presumed BPPV) after adequate trials 1, 2
• Atypical nystagmus patterns on Dix-Hallpike testing 3, 2
• Associated symptoms suggesting transient ischemic attack: diplopia, dysarthria, facial numbness occurring with episodes 3, 4

For Chronic or Recurrent Dizziness

• Progressive unilateral hearing loss with asymmetry on audiometry 2
• Persistent symptoms despite appropriate vestibular rehabilitation 1, 2
• Headache with photophobia and phonophobia may suggest vestibular migraine (not a red flag per se, but requires different management) 2

Common Pitfalls to Avoid

Do not rely on the patient's description of "spinning" versus "lightheadedness"—instead focus on timing (acute vs episodic vs chronic) and triggers (spontaneous vs positional) to categorize the vestibular syndrome. 1, 2, 4

Do not assume CT head is adequate for stroke evaluation—CT misses many posterior circulation infarcts and has sensitivity of only 20-40% for causative pathology in dizziness, whereas MRI with diffusion-weighted imaging is the appropriate study. 3, 2

Do not order routine imaging for isolated dizziness with typical peripheral features—the diagnostic yield is extremely low (<1% for CT, 4% for MRI) and most findings are incidental. 3, 1

Do not miss the opportunity to perform bedside testing—the Dix-Hallpike maneuver for suspected BPPV and HINTS examination for acute vestibular syndrome provide more diagnostic value than imaging in most cases. 1, 2