Labyrinthitis

• Definition:
  • Inflammation of the membranous labyrinth of the inner ear.
• Symptoms:
  • Vertigo (severe ‘room spinning’ sensation)
  • Nausea
  • Vomiting
  • Tinnitus (ringing in the ears)
  • Hearing loss
• Epidemiology:
  • Limited data available.
  • Incidence increases with age.
• Differential Diagnosis:
  • Conditions like cerebrovascular accident (CVA) can mimic symptoms, necessitating thorough evaluation including history, examination, and investigations.

Anatomy

• Inner Ear Structures:
  • Bony Labyrinth: Collection of bony cavities within the temporal bone.
    • Parts: Vestibule, cochlea, and three semicircular canals.
    • Contains: Perilymph.
  • Membranous Labyrinth: Located within the bony labyrinth.
    • Parts: Saccule, utricle, semicircular ducts, and cochlear duct.
    • Contains: Endolymph.
• Connections:
  • Middle Ear:
    • Oval window: Connects vestibule to middle ear.
    • Round window: Connects cochlear duct to middle ear.
  • Central Nervous System (CNS):
    • Internal auditory canal: Connects inner ear to CNS.
    • Cochlear aqueduct: Connects inner ear to CNS.

Etiology

• Causes:
  • Infections:
    • Viral: Upper respiratory tract infections, maternal rubella, cytomegalovirus (CMV), mumps, measles, herpes zoster (Ramsay-Hunt syndrome).
    • Bacterial: Meningitis, otitis media.
  • Systemic Diseases: Autoimmune diseases such as polyarteritis nodosa and granulomatosis with polyangiitis.
  • HIV/Syphilis: Possible association with opportunistic infections or direct viral impact.
• Types of Labyrinthitis:
  • Viral Labyrinthitis:
    • Common, secondary to viral infections.
    • Congenital deafness often due to maternal rubella or CMV.
    • Post-natal viral causes include mumps, measles, and reactivated varicella-zoster virus (Ramsay-Hunt syndrome).
  • Bacterial Labyrinthitis:
    • Arises from meningitis or otitis media.
    • Mechanisms:
      • Serous Labyrinthitis: Inflammation from bacterial toxins or host cytokines/inflammatory mediators.
      • Suppurative Labyrinthitis: Direct bacterial infection.
  • Autoimmune Labyrinthitis:
    • Rare complication of autoimmune diseases.
  • Labyrinthitis Ossificans:
    • Pathological bone formation within the labyrinth (rare).

Epidemiology

• Prevalence:
  • Varies widely; in South Korea, prevalence of vestibular dysfunction ranged from 3.1% to 35.4%.
  • Viral labyrinthitis is the most common form.
• Demographics:
  • Typically affects adults aged 30-60.
  • Twice as common in females.
• Childhood Cases:
  • Suppurative bacterial labyrinthitis from meningitis can cause deafness in children under age 2 (rare in post-antibiotic era).

History and Physical Examination

• Risk Factors:
  • Recent viral infections (upper respiratory tract infections).
  • Cholesteatoma or history of ear surgery.
  • Temporal bone or skull fracture.
  • Meningitis.
  • Acute/chronic otitis media.
• Symptoms:
  • Severe vertigo (initial vertigo rarely lasts longer than 72 hours).
  • Nausea and vomiting.
  • Hearing loss or tinnitus.
  • Balance issues and occasional brief episodes of vertigo may persist for weeks.
• Examination:
  • Nystagmus: Fast phase moves away from the affected ear.
  • Gait and Balance Disturbances: Test with Romberg’s and tandem gait.
  • Hearing Tests: Rinne and Weber tests (sensorineural hearing loss).
  • Otoscopy: May reveal otitis media or cholesteatoma.
  • Neurological Symptoms: Screen for numbness, weakness, dysphagia, dysarthria, and facial pain (potential CVA signs).

Evaluation

• Audiometry: Assess extent of sensorineural hearing loss.
• Vestibular System Tests: Not indicated in the acute phase but useful for long-term assessment.
• Laboratory Tests: Tailored to symptoms and differential diagnoses.
  • Electrolyte Panel: If severe vomiting is present.
  • CSF Cultures: If bacterial meningitis is suspected.
  • HIV/Syphilis Serology: In high-risk individuals or atypical presentations.
  • Autoimmune Screens: In patients with systemic symptoms or negative serology.
• Imaging: MRI and CT to rule out alternative pathology.
  • Gadolinium-enhanced MRI (GdMRI): Predicts hearing loss in bacterial meningitis.
  • CT: Useful for identifying other causes (e.g., acoustic neuroma).

Treatment/Management

• Viral Labyrinthitis:
  • Hydration and bed rest.
  • Counsel patients to seek medical help if symptoms worsen or neurological disturbances occur.
  • Limited evidence for antiviral medications and steroids.
• Bacterial Labyrinthitis:
  • Antibiotic treatment based on infection source (oral for acute otitis media, IV for meningitis or unresponsive infections).
• Autoimmune Labyrinthitis:
  • Initial management with corticosteroids.
  • Other immunomodulators (azathioprine, etanercept, cyclophosphamide) for refractory cases.
  • Specialist oversight required.
• HIV/Syphilis:
  • Appropriate treatment and specialist referral.
• Symptom Management:
  • Benzodiazepines and antihistamines (short-term) for vertigo.
  • Antiemetics (e.g., prochlorperazine) for nausea and vomiting.
  • Corticosteroids for sudden hearing loss, with specialist referral.
• Rehabilitation:
  • Vestibular rehabilitation for persistent symptoms.
  • Early mobilization to aid vestibular compensation and prognosis.
• Surgical Intervention:
  • Required in a minority of cases (e.g., mastoidectomy for cholesteatoma or severe mastoiditis).
  • Drainage of effusions or myringotomy for labyrinthitis secondary to otitis media.

Differential Diagnosis

• Vestibular Neuritis: Similar symptoms but without hearing loss.
• Meniere Disease: Intermittent episodes of vertigo and hearing loss.
• Benign Positional Vertigo: Dizziness without hearing loss, positive Dix-Hallpike test.
• Posterior Fossa CVA: Neurological signs require immediate imaging.
• Others:
  • Acoustic neuromas/vestibular schwannomas (visualized using GdMRI).
  • Inner ear malformations (diagnosed with CT or MRI).
  • Temporal bone fracture (confirmed with CT).
  • Inner ear hemorrhage (associated with trauma, demonstrated on MRI).
  • Temporal bone neoplasm (presents with cranial nerve deficits, investigated with MRI/CT).
  • Multiple sclerosis (systemic symptoms like spasticity or optic neuritis).

Complications

• Bilateral Vestibular Hypofunction: Debilitating complication from bilateral labyrinthitis (most commonly from bacterial meningitis), can result in visual impairment and reliance on mobility aids.
• Residual Hearing Loss/Tinnitus: Managed with hearing aids or tinnitus-specific therapies.
• Complete Deafness: Rare, usually from bacterial meningitis.
• Labyrinthitis Ossificans: Complication of suppurative labyrinthitis.
• Mastoiditis: Risk if bacterial labyrinthitis is not treated effectively; may require mastoidectomy with tympanoplasty in severe cases.
• Labyrinthectomy: Rarely required, e.g., in cholesteatoma-induced labyrinthitis.

Prognosis

• Acute Vertigo: Should resolve within a couple of days.
• Mild Symptoms: May persist for several weeks.
• Serious Neurological Sequelae: Require further interventions (e.g., ventriculoperitoneal shunts for hydrocephalus).
• Delayed Vestibular Recovery: Prolonged use of benzodiazepines/antihistamines can delay recovery.
• Permanent Hearing Impairment: More likely with suppurative labyrinthitis.

Deterrence and Patient Education

• Infection Control: Early diagnosis and management of primary infections (e.g., otitis media, meningitis) to prevent labyrinthitis.
• Vaccinations: Important to reduce the risk of contracting measles, mumps, or rubella.
• Mobilization: Encourage patients to mobilize early to aid vestibular compensation and prognosis.

Enhancing Healthcare Team Outcomes

• Interprofessional Approach:
  • Coordination between primary care, nurses, pharmacists, occupational and physiotherapists.
  • Ensure all team members are aware of labyrinthitis signs, symptoms, and differential diagnoses.
• Nurses:
  • Assist with patient transfers due to vertigo, prevent falls.
  • Allow patients extra time for tasks due to vertigo.
• Pharmacists:
  • Advise on appropriate medications for symptom management.
  • Monitor for adverse effects and drug interactions.
• Occupational Therapists:
  • Assess home environment, implement safety changes.
• Physiotherapists:
  • Provide vestibular rehabilitation, improve symptoms.