What is the diagnosis and treatment for a 2-week history of dizziness that began after a viral upper respiratory infection, worsened by head movements, with mild horizontal nystagmus, and partially relieved by Bonine (meclizine)?

Diagnosis: Vestibular Neuritis (Post-Viral Labyrinthitis)

This patient has vestibular neuritis, a peripheral vestibular disorder that developed following a viral upper respiratory infection, characterized by prolonged dizziness with mild horizontal nystagmus that partially responds to meclizine. 1, 2

Clinical Reasoning

The clinical presentation strongly points to a peripheral vestibular etiology rather than central pathology:

• Timing and onset: The 2-week duration following a viral URI is classic for vestibular neuritis, which typically presents with acute severe vertigo lasting days to weeks after viral infection 2, 3
• Nystagmus pattern: Mild horizontal nystagmus is characteristic of peripheral vestibular disorders; central causes typically produce pure vertical nystagmus without torsional component or direction-changing nystagmus 2
• Symptom evolution: Initial severe vertigo that gradually improves to persistent imbalance over 2 weeks follows the expected course of vestibular neuritis 1
• Trigger pattern: Worsening with sudden head movements but not strictly positional (unlike BPPV) fits vestibular neuritis 3

Distinguishing from Other Diagnoses

This is NOT BPPV because:

• BPPV causes brief episodes (seconds to <1 minute) of vertigo with specific positional changes 1
• This patient has continuous dizziness/imbalance for 2 weeks, not brief episodic symptoms 1
• BPPV would show characteristic fatigable, latent nystagmus on Dix-Hallpike testing 1

This is NOT labyrinthitis because:

• Labyrinthitis includes hearing loss, tinnitus, or aural fullness in addition to vertigo 1
• No hearing symptoms are mentioned in this case 1

Central causes are unlikely because:

• No neurological deficits (dysarthria, dysmetria, dysphagia, motor/sensory deficits) 2
• Horizontal nystagmus rather than pure vertical 2
• Partial response to meclizine suggests peripheral etiology 4

Diagnostic Workup

No imaging is required for this typical presentation:

• Imaging is unnecessary in acute persistent vertigo with normal neurologic examination and peripheral HINTS findings 1
• CT detection rate of contributory CNS pathology in patients with normal neurologic exam is <1% 1
• MRI would only be indicated if atypical features were present (pure vertical nystagmus, neurologic deficits, failure to improve) 1

Perform bedside examination:

• Complete Dix-Hallpike maneuver to definitively exclude BPPV 1
• HINTS examination (head-impulse, nystagmus, test of skew) to confirm peripheral localization 2, 3
• Assess for additional neurologic signs that would suggest central pathology 2

Treatment Approach

Discontinue meclizine after the acute phase (now, at 2 weeks):

• Meclizine is FDA-approved for vertigo associated with vestibular system diseases 4
• However, vestibular suppressants should only be used during the acute severe phase (first 2-3 days) 3, 5
• Continued use beyond the acute phase impairs central compensation and prolongs recovery 5
• The partial relief he experiences is actually hindering his recovery 5

Initiate vestibular rehabilitation immediately:

• Vestibular rehabilitation is the primary treatment for vestibular neuritis 3, 5
• Active head movements and balance exercises promote central compensation 5
• This addresses his persistent imbalance more effectively than continued medication 3, 5

Expected recovery timeline:

• Most patients show significant improvement within 4-6 weeks with appropriate vestibular rehabilitation 3
• Some residual imbalance may persist for several months but continues to improve 1

Red Flags Requiring Urgent Re-evaluation

Watch for features suggesting central pathology that would mandate immediate MRI:

• Development of pure vertical or direction-changing nystagmus 2
• New neurologic symptoms (diplopia, dysarthria, dysphagia, weakness, sensory changes) 2
• Severe headache suggesting vertebrobasilar stroke 2
• Worsening symptoms or failure to improve over the next 2-4 weeks 1, 2