# Vertigo and Dizziness: Sorting Benign from Dangerous

## Overview and Classification

### The Dizziness Problem

Dizziness accounts for 3 to 4 percent of ED visits. The traditional approach of classifying dizziness by "type" — vertigo versus presyncope versus disequilibrium versus lightheadedness — is unreliable because patients often cannot articulate the difference. The modern approach classifies dizziness by timing and triggers rather than type. Episodic triggered dizziness suggests BPPV (positional). Episodic spontaneous dizziness suggests vestibular migraine, Meniere's disease, cardiac arrhythmia, or panic. Acute continuous dizziness suggests vestibular neuritis or cerebellar/brainstem stroke. Chronic dizziness suggests persistent postural-perceptual dizziness (PPPD) or multisensory deficit.

### The Critical Question

The primary ED concern is whether the cause is peripheral (benign) or central (dangerous). Central causes such as stroke and hemorrhage require emergent intervention, while peripheral causes are managed symptomatically. Posterior circulation stroke accounts for approximately 3 to 5 percent of acute vestibular syndrome presentations and cannot be missed.

## Acute Vestibular Syndrome (AVS)

### Definition

The acute vestibular syndrome is defined as acute onset of continuous vertigo, nausea and vomiting, gait instability, nystagmus, and head motion intolerance lasting more than 24 hours. The two main causes are vestibular neuritis (benign) and posterior circulation stroke (dangerous).

### HINTS Examination

The HINTS examination — Head Impulse, Nystagmus, and Test of Skew — is a three-component bedside oculomotor examination that outperforms MRI in the first 48 hours for detecting posterior circulation stroke, with a sensitivity of 98 percent compared to 80 percent for MRI in the first 24 to 48 hours. However, the published sensitivity and specificity data come from neuro-ophthalmology and neurology experts, and generalizability to ED physicians without specific training is uncertain.

#### Head Impulse Test (HI)

The examiner rapidly turns the patient's head to each side while the patient fixates on the examiner's nose. A normal result (no corrective saccade) is the central and dangerous finding — the vestibular nerve is intact, meaning the problem lies in the brainstem or cerebellum. An abnormal result (a corrective saccade is present) is the peripheral and reassuring finding — the vestibular nerve itself is damaged. This is counterintuitive: a "normal" head impulse test in the acute vestibular syndrome is the concerning finding.

#### Nystagmus

Unidirectional, horizontal nystagmus that always beats in the same direction regardless of gaze is peripheral and reassuring. Direction-changing (gaze-evoked) nystagmus that changes direction with gaze is central and dangerous. Purely vertical or purely torsional nystagmus is central and dangerous.

#### Test of Skew

The cover-uncover test is performed to look for vertical refixation movement (skew deviation). A positive skew is central and dangerous, suggesting a brainstem lesion. A negative skew is peripheral and reassuring.

#### HINTS Summary

A HINTS peripheral pattern — all three components reassuring (abnormal head impulse, unidirectional nystagmus, and no skew) — points to vestibular neuritis. A HINTS central pattern — any one dangerous feature (normal head impulse, direction-changing nystagmus, or positive skew) — should raise concern for stroke, and MRI/MRA should be obtained. The HINTS examination only applies in the setting of the acute vestibular syndrome (continuous vertigo with nystagmus) and must not be applied to episodic or triggered dizziness.

| HINTS Component | Peripheral (Reassuring) | Central (Dangerous) |
|----------------|------------------------|-------------------|
| Head Impulse | Abnormal (corrective saccade present) | Normal (no saccade — nerve intact, central problem) |
| Nystagmus | Unidirectional, horizontal | Direction-changing, vertical, or torsional |
| Test of Skew | Negative (no vertical refixation) | Positive (vertical refixation present) |
| **Interpretation** | **All 3 peripheral = vestibular neuritis** | **Any 1 central = consider stroke** |

### Vestibular Neuritis

Vestibular neuritis is an acute unilateral peripheral vestibulopathy and the most common cause of the acute vestibular syndrome. It is often post-viral, with HSV reactivation in the vestibular ganglion proposed as a mechanism. It presents with severe vertigo, nausea, and nystagmus (unidirectional, with the fast phase beating away from the affected side). There is no hearing loss, which distinguishes it from labyrinthitis (which has hearing loss). Treatment is symptomatic relief for 24 to 48 hours only — vestibular suppressants impair central compensation if used longer. Ondansetron is used for nausea, and meclizine 25 mg orally every 8 hours or dimenhydrinate provides vestibular suppression. A short course of corticosteroids (a methylprednisolone taper) may improve long-term recovery based on moderate evidence. Early mobilization should be encouraged for vestibular rehabilitation.

## Benign Paroxysmal Positional Vertigo (BPPV)

### Pathophysiology

BPPV occurs when otoconia (calcium carbonate crystals) dislodge from the utricle and enter a semicircular canal. The posterior canal is most commonly affected (80 to 90 percent). Episodes are brief (less than 1 minute), intense, and provoked by specific head positions such as rolling over in bed, looking up, or bending forward.

### Diagnosis

The Dix-Hallpike maneuver is the gold standard for diagnosing posterior canal BPPV. The patient is moved from a seated position to supine with the head turned 45 degrees and hanging slightly off the table. A positive test produces a brief latency of 2 to 5 seconds, followed by upbeat-torsional nystagmus lasting less than 1 minute, with fatigability on repeat testing. The latency, brief duration, and fatigability distinguish BPPV from central positional nystagmus. The supine roll test is used for lateral (horizontal) canal BPPV, producing horizontal nystagmus with head turns in the supine position.

### Treatment

The Epley maneuver (canalith repositioning) is the treatment for posterior canal BPPV, with a success rate of 80 to 90 percent after 1 to 2 treatments. The Lempert (BBQ roll) maneuver is used for lateral canal BPPV. Post-procedure restrictions such as sleeping upright or avoiding the affected side are not evidence-based and are unnecessary. Vestibular suppressants are generally not needed for BPPV because the episodes are too brief — routine meclizine prescriptions for BPPV should be avoided.

## Posterior Circulation Stroke

### Why It Is Missed

Posterior circulation strokes account for 20 percent of all strokes but are disproportionately missed. Their symptoms overlap extensively with benign vestibular conditions. CT has poor sensitivity for posterior fossa ischemia (less than 30 percent). Even MRI with DWI can be false-negative in the first 24 to 48 hours (with an up to 20 percent miss rate).

### Red Flags Suggesting Central Cause

Red flags that should raise suspicion for a central cause include inability to walk (severe gait ataxia) — vestibular neuritis patients can usually walk with support — new headache (especially occipital), cranial nerve deficits (diplopia, facial weakness, dysarthria, and dysphagia), crossed findings (ipsilateral face and contralateral body), any HINTS central pattern, and cardiovascular risk factors (atrial fibrillation, hypertension, diabetes, and prior stroke).

### Specific Syndromes

Lateral medullary syndrome (Wallenberg) presents with vertigo, ipsilateral facial numbness, contralateral body numbness, dysarthria, dysphagia, ipsilateral Horner syndrome, and ipsilateral limb ataxia, and involves the PICA territory. Cerebellar infarction presents with severe vertigo, ataxia, and headache, with a risk of edema and herniation that may require emergent decompressive surgery. AICA infarction presents with vertigo and ipsilateral hearing loss (distinguishing it from vestibular neuritis) along with facial weakness.

## Other Important Causes

### Meniere Disease

Meniere disease presents with episodic vertigo lasting 20 minutes to hours, fluctuating sensorineural hearing loss, tinnitus, and aural fullness. It is unilateral in most cases. The ED role is symptom management and ENT referral. Treatment includes vestibular suppressants, antiemetics, and a low-salt diet, with intratympanic gentamicin or surgery reserved for refractory cases.

### Vestibular Migraine

Vestibular migraine is the most common cause of episodic spontaneous vertigo. It presents with vertigo lasting minutes to 72 hours accompanied by migrainous features (headache, photophobia, phonophobia, and visual aura). Importantly, 50 percent of patients may not have a headache during the episode, making diagnosis challenging and requiring a high index of suspicion. Treatment includes migraine abortive therapy and prophylaxis if the episodes are recurrent.

### Medication-Induced Dizziness

Common culprits for medication-induced dizziness include antihypertensives, anticonvulsants, benzodiazepines, aminoglycosides, and loop diuretics. The medication list should always be reviewed in patients presenting with dizziness.

<image>A three-panel instructional diagram showing the HINTS examination. Panel 1: Head Impulse Test — examiner rapidly turning the patient's head to the right while the patient fixates on the examiner's nose, with two outcomes shown: (A) corrective saccade present = peripheral (reassuring), (B) eyes stay fixed on target, no saccade = central (dangerous). Panel 2: Nystagmus assessment — two eyes showing (A) unidirectional horizontal nystagmus in all gaze directions = peripheral, and (B) direction-changing gaze-evoked nystagmus = central. Panel 3: Test of Skew — cover-uncover test showing (A) no vertical eye movement when uncovered = negative = peripheral, and (B) vertical refixation movement when uncovered = positive skew = central. A summary box states: any ONE central feature = consider stroke.</image>

<image>A step-by-step illustration of the Dix-Hallpike maneuver and Epley maneuver. Top row (Dix-Hallpike): Step 1 — patient seated with head turned 45 degrees to the right. Step 2 — patient rapidly moved to supine with head hanging 20 degrees below the table, maintaining 45-degree rotation. Step 3 — examiner observes for upbeat-torsional nystagmus after a brief latency. Bottom row (Epley): Step 1 — from positive Dix-Hallpike position, maintain for 30 seconds until nystagmus resolves. Step 2 — rotate head 90 degrees to the opposite side (now 45 degrees to the left), hold 30 seconds. Step 3 — roll patient onto their side with head turned to face the floor at 45 degrees, hold 30 seconds. Step 4 — sit patient up. Arrows show the path of otoconia through the posterior semicircular canal during each step.</image>

<image>A diagnostic algorithm flowchart for acute dizziness in the ED. Starting with "Acute dizziness presentation" splitting into three branches based on timing: "Episodic, triggered by position" (leads to Dix-Hallpike, if positive = BPPV, treat with Epley), "Episodic, spontaneous" (differential includes vestibular migraine, Meniere's, TIA, arrhythmia — workup based on associated features), and "Acute continuous (AVS)" (leads to HINTS exam: if all peripheral features = vestibular neuritis, if any central feature = MRI/MRA, vascular neurology consult for posterior circulation stroke). Red flags are listed: inability to walk, new headache, cranial nerve deficits, direction-changing nystagmus, positive skew, cardiovascular risk factors.</image>

## Clinical Pearls

The HINTS exam outperforms MRI in the first 48 hours for posterior circulation stroke detection, but it requires training and practice to perform reliably. A "normal" head impulse test in the acute vestibular syndrome is the dangerous finding (counterintuitively) — it means the vestibular nerve is intact and the problem is central. CT is nearly useless for posterior fossa stroke — if a central cause is suspected, MRI should be obtained, keeping in mind that even MRI can be false-negative in the first 24 to 48 hours. BPPV episodes last less than 1 minute — if vertigo lasts longer than 1 minute, it is not BPPV. The Epley maneuver treats BPPV in 80 to 90 percent of cases, and prescribing meclizine instead of performing the Epley is a missed opportunity. Inability to walk is the single strongest predictor of a central cause in acute dizziness — vestibular neuritis patients can walk, though unsteadily. Vestibular suppressants should be limited to 24 to 48 hours because prolonged use impairs central compensation and delays recovery. The HINTS examination only applies in the acute vestibular syndrome (continuous vertigo with nystagmus) and must not be applied to episodic dizziness.

## References

- Kattah JC, et al. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. *Stroke*. 2009;40:3504-3510.
- Newman-Toker DE, et al. HINTS outperforms ABCD2 to screen for stroke in acute continuous vertigo and dizziness. *Acad Emerg Med*. 2013;20:986-996.
- Hilton MP, Pinder DK. The Epley manoeuvre for benign paroxysmal positional vertigo. *Cochrane Database Syst Rev*. 2014;12:CD003162.
- Strupp M, et al. Methylprednisolone, valacyclovir, or the combination for vestibular neuritis. *NEJM*. 2004;351:354-361.
- Edlow JA, et al. A new diagnostic approach to the adult patient with acute dizziness. *J Emerg Med*. 2018;54:469-483.