How should I evaluate and manage peripheral (lower‑motor‑neuron) nystagmus presenting with vertigo, imbalance, nausea, and possible hearing loss?

Evaluation and Management of Peripheral Nystagmus with Vertigo

Immediate Clinical Assessment

Peripheral (lower motor neuron) nystagmus presenting with vertigo, imbalance, nausea, and possible hearing loss most commonly represents benign paroxysmal positional vertigo (BPPV), vestibular neuritis, or Ménière's disease—and your first priority is to distinguish these benign peripheral causes from life-threatening posterior circulation stroke, which can mimic peripheral vestibular disorders in approximately 10% of cases. 1

Key Distinguishing Features of Peripheral Nystagmus

Peripheral vestibular nystagmus exhibits specific characteristics that help differentiate it from central pathology:

• Horizontal with rotatory (torsional) component, never purely vertical 1, 2
• Unidirectional—the fast phase beats in the same direction regardless of gaze position 1
• Suppressed by visual fixation—asking the patient to focus on a target reduces nystagmus intensity 1
• Fatigable—repeated positional testing causes the nystagmus to diminish or disappear 1
• Brief latency period (5–20 seconds) before onset when triggered by position changes 1, 3

Red Flags Demanding Urgent Neuroimaging

Any of the following features indicate possible central (stroke) pathology and mandate immediate MRI brain without contrast 1, 3:

• Pure vertical nystagmus (up-beating or down-beating) without torsional component 1
• Direction-changing nystagmus that switches direction with gaze changes 1
• Baseline nystagmus present without provocative maneuvers 1
• Nystagmus that does not fatigue with repeated testing 1
• Severe postural instability with falling—inability to stand or walk 1, 3
• New-onset severe headache accompanying vertigo 1, 3
• Any focal neurological deficits: dysarthria, limb weakness, diplopia, dysphagia, sensory loss, Horner's syndrome 1
• Sudden unilateral hearing loss 3
• Age >50 years with vascular risk factors (hypertension, diabetes, atrial fibrillation, prior stroke), even with normal neurologic exam 3

Diagnostic Algorithm

Step 1: Perform the Dix-Hallpike Maneuver Bilaterally

Execute the Dix-Hallpike test on both sides immediately to diagnose or exclude BPPV, which accounts for 42% of all peripheral vertigo cases 1, 3:

• Move patient from seated to supine position with head turned 45° to the side being tested and neck extended 20° 3
• Positive result shows torsional up-beating nystagmus with 5–20 second latency, crescendo-decrescendo pattern, resolving within 60 seconds 1, 3
• If Dix-Hallpike is negative bilaterally, perform supine roll test to detect lateral-canal BPPV (10–15% of BPPV cases) 3

Step 2: Assess Hearing and Auditory Symptoms

Document presence, laterality, and fluctuation of hearing loss, tinnitus, and aural fullness to distinguish between peripheral vestibular etiologies 4, 1:

• Ménière's disease: fluctuating low-to-mid frequency sensorineural hearing loss, episodic vertigo lasting 20 minutes to 12 hours, tinnitus, and aural fullness 4, 1
• Vestibular neuritis: acute onset severe rotatory vertigo lasting days to weeks, horizontal spontaneous nystagmus toward unaffected ear, no hearing loss 1, 2
• Labyrinthitis: sudden severe vertigo with profound, non-fluctuating hearing loss 1

Step 3: Evaluate Episode Duration and Triggers

The temporal pattern of vertigo episodes is the most diagnostically useful feature 1, 3, 5:

• Seconds (<1 minute): BPPV—triggered by specific head position changes 1, 3
• Minutes (<30 minutes): vertebrobasilar insufficiency (central cause requiring vascular imaging) 1, 5
• 20 minutes to 12 hours: Ménière's disease 4, 1
• Days to weeks (continuous): vestibular neuritis or posterior circulation stroke 1, 6

Management Based on Diagnosis

BPPV (Positive Dix-Hallpike)

Perform the Epley canalith repositioning maneuver immediately upon diagnosis 4, 1, 3:

• Success rate: 80% after 1–3 treatments, 90–98% with additional maneuvers if initial treatment fails 1, 3
• Do not prescribe vestibular suppressants (meclizine, dimenhydrinate, benzodiazepines) for BPPV—they prevent central compensation and do not address the mechanical pathology 1, 3
• No imaging or laboratory testing is needed for typical BPPV with positive Dix-Hallpike and no red flags 4, 1, 3
• Reassess within 1 month to document resolution or persistence 1, 3

Vestibular Neuritis (Suspected)

Vestibular neuritis accounts for 41% of peripheral vertigo cases and presents with acute continuous vertigo lasting days 1, 2:

• Key features: horizontal spontaneous nystagmus toward unaffected ear, pathologic head-impulse test, no hearing loss 2
• Treatment: early vestibular rehabilitation to promote central compensation 2
• Vestibular suppressants may be used briefly (2–3 days maximum) for severe acute symptoms only 2

Ménière's Disease (Suspected)

Obtain comprehensive audiometry to document fluctuating low-to-mid frequency sensorineural hearing loss 4, 1:

• Diagnostic criteria require at least two spontaneous vertigo episodes lasting 20 minutes to 12 hours, plus fluctuating hearing loss and aural symptoms 4
• Initial management: dietary sodium restriction (1500–2300 mg daily), diuretics 4
• Consider MRI head and internal auditory canal with and without contrast to exclude vestibular schwannoma in chronic recurrent vertigo with unilateral hearing loss 3

When Imaging IS Required

Order urgent MRI brain without contrast (with diffusion-weighted imaging) if any red flag is present 1, 3:

• MRI has 4% diagnostic yield versus <1% for CT in isolated dizziness 3
• CT head misses most posterior circulation infarcts (sensitivity 10–20%) and should not substitute for MRI when stroke is suspected 3
• Approximately 25% of acute vestibular syndrome presentations are posterior circulation stroke, rising to 75% in high-vascular-risk cohorts 1, 3

Common Pitfalls to Avoid

• Do not assume peripheral cause based on nystagmus alone—10% of cerebellar strokes present identically to peripheral vestibular disorders 1
• Do not rely on absence of focal neurologic deficits to exclude stroke—75–80% of posterior circulation strokes present without focal findings 3
• Do not order imaging for typical BPPV with positive Dix-Hallpike and no red flags—diagnostic yield <1% 4, 1, 3
• Do not use vestibular suppressants for BPPV—they delay recovery and do not treat the underlying mechanical problem 1, 3
• Do not overlook medication-induced dizziness—antihypertensives, anticonvulsants, and cardiovascular drugs are common reversible causes 4, 1
• Isolated transient vertigo may precede vertebrobasilar stroke by weeks to months—maintain high suspicion in older adults with vascular risk factors 1