Description

• Acute inflammation of the labyrinth (the organs of hearing and balance that comprise the bony inner ear). Infection (viral/bacterial) and subsequent inflammation of the inner ear is felt to be the most common etiology. Labyrinthitis is a clinical diagnosis in absence of neurologic deficits.
• Typically presents with false sense of motion (i.e., vertigo) or room spinning vertigo lasting for hours or days AND often sudden hearing loss in 1 ear.
• System(s) affected: Nervous; Special sensory (auditory and vestibular)
• Synonym(s): Acute peripheral vestibulopathy; Vestibular neuronitis (vertigo/dizziness only); Vestibular neuritis (vertigo/dizziness only)

• “Vertigo” and “dizziness” are commonly used terms. Clarify symptoms by giving options of alternative descriptions, such as light-headedness, dysequilibrium, room-spinning vertigo, or imbalance.
• Benign positional vertigo (BPPV) is the most common cause of room-spinning vertigo. Unlike labyrinthitis, BPPV is episodic and is diagnosed using the Dix-Hallpike maneuver. The associated vertigo is often severe, but lasts <1 minute each time. Rarely, some may report a sense of dysequilibrium lasting for hours after the initial event.

• Acute infectious labyrinthitis is often associated with vestibular hypofunction of the involved ear. Peripheral vertigo improves over time with central compensation.
• Elderly less likely to compensate fully and may report symptoms of dysequilibrium lasting weeks after resolution of the acute vertigo.
• Avoid excessive use of scopolamine, meclizine, and other vestibular suppressants following the initial event, especially in the elderly, as this will delay central compensation.

Pediatric Considerations
Unusual in this age group, except meningogenic suppurative labyrinthitis, which more commonly affects children <2 years of age.

Epidemiology

• Rare in children; most common in middle age (30–60 years)
• Predominant sex: Female = Male

• Viral labyrinthitis is the most common etiology.
• Suppurative or serous labyrinthitis secondary to otitis media is increasingly rare in the postantibiotic era. Estimated 0.5–3% of intratemporal complications of otitis media in recent studies. Higher rates in cases with cholesteatoma

Prevalence
In the US, 2nd most common cause of dizziness due to persistent peripheral vestibular hypofunction (9%); benign positional vertigo (16%) is most common. These numbers are believed to be underestimated.

Risk Factors

• Viral upper respiratory infection
• Otitis media
• Cholesteatoma
• History of allergies
• Smoking
• Excessive alcohol consumption
• Herpes zoster infection
• Head trauma
• Meningitis
• Vestibulotoxic/Ototoxic medications
• Otosyphilis (congenital or acquired)
• Tuberculosis
• Cerebrovascular disease
• Autoimmune disease

Genetics
No known genetic link.

General Prevention

• Scheduled immunizations (to prevent common viral pathogens)
• Prevent maternal transmission of pathogens, including syphilis, HIV

Pathophysiology

Acute inflammation/damage to the inner ear, involving the peripheral special sensory organs of hearing and balance:

• Viruses may pass hematogenously into the labyrinth or directly from the middle ear to labyrinth via the round/oval window.
• Bacterial toxins and host inflammatory mediators (e.g., cytokines) from a middle ear infection may reach the inner ear. In serous labyrinthitis, bacteria are not present in the inner ear.
• In suppurative labyrinthitis, the infecting organism obtains direct access into the inner ear:
  • Otogenic: Usually unilateral. Enters via round/oval window to the labyrinth. May also enter via dehiscent horizontal semicircular canal if there is associated cholesteatoma.
  • Meningogenic: Can be bilateral. Enters by way of CSF via internal auditory canal or cochlear aqueduct.
• Ischemia: Ischemic or thromboembolic events involving the labyrinthine artery can cause symptoms that mimic acute labyrinthitis. May have other associated neurologic symptoms
• Autoimmune: Local or systemic inflammatory processes may affect the inner ear directly via autoantibodies or indirectly via a vasculitis of the labyrinthine artery.

Etiology

• Infections:
  • Common viral: Cytomegalovirus, mumps, varicella zoster, rubeola, influenza, parainfluenza, herpes simplex, adenovirus, coxsackievirus, respiratory syncytial virus, HIV
  • Common bacterial: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Neisseria meningitidis, Streptococcus sp., Staphylococcus species, Borrelia burgdorferi
  • Treponemal: Treponema pallidum
• Autoimmune:
  • Wegener granulomatosis
  • Cogan syndrome
  • Systemic lupus erythematous
  • Polyarteritis nodosa
  • Behçet disease
• Ischemia/Infarction
• Ototoxic drugs (e.g., aspirin, aminoglycosides, cisplatin)

Commonly Associated Conditions

• Viral upper respiratory infection
• Allergies
• Otitis media
• Cholesteatoma
• Head injury