Vestibular Neuronitis

• Definition: Inflammation of the vestibular portion of the eighth cranial nerve, presenting with vertigo, nausea, and gait imbalance.
• Nature: Benign, self-limited condition lasting several days; complete resolution of symptoms can take weeks to months.
• Diagnosis: Clinical, requiring differentiation from central causes like cerebrovascular syndromes.
• Treatment: Supportive, including antiemetics, antihistamines, and benzodiazepines; vestibular rehabilitation after nausea/vomiting control.

Introduction

• Cause: Believed to be associated with viral infection, causing inflammation of the vestibular portion of the eighth cranial nerve.
• Presentation: Acute onset of vertigo, nausea, vomiting, and gait imbalance.
• Prognosis: Typically resolves without intervention; vestibular symptoms can persist for weeks to months.

Etiology

• Presumed Cause: Viral origin (e.g., reactivation of latent HSV infection).
• Other Theories: Vascular etiology and immunologic factors.

Epidemiology

• Incidence: Third most common cause of peripheral vertigo after BPPV and Meniere disease.
• Prevalence: Diagnosed in 6% of patients presenting with dizziness in emergency departments in the USA.
• Demographics: No gender preference; commonly affects middle-aged individuals.

Pathophysiology

• Mechanism: Inflammation affecting the superior division of the vestibular nerve more than the inferior division.
• Histologic Findings: Vestibular damage with predilection for the superior vestibular labyrinth.

History and Physical Examination

• Symptoms:
  • Vertigo: Constant, worsened with head movement.
  • Nausea/Vomiting: Common.
  • Balance Problems: Acute onset, peaks within 24-48 hours.
  • Preceding Viral Illness: Noted in up to 50% of patients.
• Differential Symptoms: Absence of headaches; accompanying symptoms (visual changes, somatosensory changes, weakness, dysarthria, incoordination) may indicate central causes.
• Physical Exam:
  • Normal Neurological Exam: Peripheral vertigo findings include a negative HINTS exam.
  • HINTS Exam: High sensitivity and specificity for distinguishing peripheral from central vertigo.
  • Components of HINTS Exam:
    • Head Impulse Test: Positive test indicates peripheral etiology.
    • Nystagmus: Horizontal or horizontal-torsional, unidirectional indicates peripheral cause.
    • Test of Skew: No eye deviation indicates peripheral cause.

Evaluation

• Diagnosis: Based on clinical signs and symptoms.
• Imaging: MRI preferred over CT if central causes need to be ruled out; not typically indicated unless symptoms persist or risk factors for stroke exist.
• Additional Tests: Cervical and ocular vestibular evoked myogenic potentials, video head impulse testing.

Treatment / Management

• Symptomatic Treatment:
  • Antiemetics: Promethazine 12.5-25 mg every 4-6 hours, Metoclopramide 10 mg three times daily.
  • Antihistamines: Diphenhydramine 25-50 mg every 4-6 hours, Meclizine 25-50 mg up to three times daily.
  • Benzodiazepines: Diazepam 2-5 mg three times daily, Lorazepam 0.5-1 mg three times daily (use for no more than 3 days)..
  • Duration: Use for no more than three days to avoid delaying central compensation.
• Vestibular Rehabilitation: Recommended after acute symptoms are controlled.
• Corticosteroids: Efficacy controversial; insufficient evidence to recommend.
• Antiviral Medications: Valacyclovir not shown to be effective.

Differential Diagnosis

• Peripheral Causes:
  • Benign Paroxysmal Positional Vertigo (BPPV): Episodic vertigo with head movements.
  • Meniere Disease: Recurrent episodes with sensory symptoms (ear fullness, tinnitus).
  • Labyrinthitis: Similar to vestibular neuritis but includes unilateral hearing loss.
• Central Causes:
  • Vestibular Migraine: Central/peripheral signs, recurrent episodes, associated with migraine.
  • Vertebrobasilar TIA: Vascular risk factors, acute onset, short duration.
  • Brainstem Ischemia/Infarct: Acute onset, neurological symptoms, history of trauma.
  • Cerebellar Infarct/Hemorrhage: Vascular risk factors, associated neurological deficits.
• With Hearing Loss:
  • Perilymphatic Fistula
  • Cholesteatoma
  • Meniere Disease
  • Labyrinthitis
  • Acoustic Neuroma
  • Autoimmune Processes
• Without Hearing Loss:
  • BPPV
  • Vertebral Basilar Insufficiency
  • Migraines
  • Vestibulopathy
  • Vestibular Neuronitis
  • CNS Disorders
  • Lyme Disease
  • Multiple Sclerosis

Prognosis

• Outcome: Typically uncomplicated with complete resolution in most cases.
• Persistent Symptoms: 15% with symptoms at one year.
• Recurrence: Infrequent (2-11% of patients).

Complications

• Benign Paroxysmal Positional Vertigo (BPPV): Develops in 10-15% of patients within weeks.
• Persistent Postural-Perceptual Dizziness (PPPD): Non-spinning vertigo, unsteadiness, found in 25% of patients followed 3-12 months after acute vestibular disorders.

Deterrence and Patient Education

• Acute Onset of Persistent Vertigo: Suggests vestibular neuritis.
• Consultation: Seek consultation with primary care, emergency, or ENT physician.
• Primary Evaluation: Exclude severe brain or vascular diseases, refer to ENT for further testing.

Enhancing Healthcare Team Outcomes

• Interprofessional Approach:
  • Role of Pharmacists: Medication reconciliation, verify dosing, counsel on administration and adverse effects.
  • Role of Nurses: Monitor treatment progress, answer patient questions, report concerns to clinicians.
  • Vestibular Rehabilitation: Early improvement through individually designed programs.
  • Collaborative Effort: Essential for optimal patient care, especially in distinguishing vestibular neuritis from central causes like cerebrovascular events.