Vestibular neuritis

Vestibular neuritis (VN) is the idiopathic inflammation of the vestibular nerve. Although the etiology is unclear, it is thought to be viral in origin because it commonly occurs after upper airway infections. The disorder manifests as acute vestibular syndrome with persistent, acute-onset vertigo, nausea and vomiting, and gait instability in otherwise healthy patients. When hearing loss is present, it is sometimes referred to as labyrinthitis. Diagnosis is clinical and should include a complete otoneurological examination to exclude a central cause of acute vestibular syndrome, such as cerebellar stroke or lateral medullary syndrome. Vestibular rehabilitation therapy is the most important aspect of treatment and should be initiated as soon as possible. Symptomatic therapy with vestibular suppressants may be considered during the acute phase. Glucocorticoids are no longer routinely recommended as there is insufficient evidence regarding their long-term efficacy. The acute phase of severe vertigo usually lasts a few days and symptoms typically resolve in 2–3 weeks with treatment. In refractory cases, which are rare, vestibular ablation therapy or surgery involving the inner ear may be necessary.

See also “Vertigo.”

See also “Acute vestibular syndrome.”

• Vestibular neuritis: inflammation of the vestibular nerve with features of vestibular hypofunction, such as vertigo, nausea, vomiting, and gait instability, usually without hearing loss ^[1][2]
• Labyrinthitis: ipsilateral sensorineural hearing loss associated with features of vestibular neuritis ^[1]
• Acute peripheral vestibulopathy: a term used to encompass peripheral causes of acute vestibular syndrome (i.e., vestibular neuritis and labyrinthitis) ^[3]

The term dizziness is nonspecific and is variably used to describe distinct symptoms such as vertigo, presyncope, imbalance, and confusion.

• Second most common cause of vertigo (after BPPV) ^[4]
• Age: peak incidence at 30–50 years of age
• Sex: ♀ = ♂ ^[2]

Epidemiological data refers to the US, unless otherwise specified.

• Idiopathic inflammation of the vestibular nerve
• Tends to occur more often after upper airway infections ^[2][5]

• Acute or subacute onset ^[1][4]
  • Severe vertigo: persistent and continuous, often exacerbated by head motion
  • Nausea and vomiting
  • Gait instability
  • Increased risk of falling toward the affected side
  • Nystagmus (spontaneous horizontal unilateral)
  • Oscillopsia
• Progression and duration of symptoms
  • Usually develop over several hours
  • Severe symptoms usually last for 1–2 days
  • Mild symptoms may persist for weeks or even months.
• Examination
  • Characteristic findings on HINTS examination
  • Neurological examination is otherwise normal.

Cochlear symptoms (e.g., hearing loss, tinnitus) are usually absent in vestibular neuritis.

The presence of neurological abnormalities (e.g., truncal ataxia) in a patient with acute vestibular syndrome should raise suspicion for a central cause (e.g., cerebellar stroke, lateral medullary syndrome).

Labyrinthitis

• Definition: inflammation of the inner ear, notably the membranous labyrinth
• Epidemiology
  • Peak incidence: 30–50 years of age ^[6]
  • ♀ > ♂ (1,5:1) ^[6]
• Etiology
  • Infectious: viruses, bacteria, fungi
    • Viral labyrinthitis
      • Congenital: rubella, cytomegalovirus
      • Acquired: mumps, measles, herpes simplex virus, influenza, HIV, varicella zoster virus (see “Herpes zoster oticus”)
    • Bacterial labyrinthitis; : typically a complication of acute otitis media, meningitis, mastoiditis, syphilis, or cholesteatoma ^[7]
  • Autoimmune systemic diseases (e.g., due to vasculitis)
  • Other: head trauma, vascular ischemia, ototoxic drugs (e.g., aminoglycosides)
• Pathophysiology: toxins or bacteria spread to the inner ear (labyrinth) through the round or oval window
• Clinical features
  • Severe vertigo, nausea, and vomiting
  • Hearing loss, tinnitus
  • Nystagmus direction toward healthy ear: Labyrinthitis causes decreased vestibular activity (due to damage) and is typically associated with nystagmus toward the healthy ear. ^[8][9]
  • Fever, ear rash, facial paralysis in case of herpes zoster oticus
• Diagnostics
  • See “Diagnostics” below
  • Bacterial labyrinthitis
    • Complication of otitis media: change of lateralization in Weber test
    • Audiometry confirms sensorineural hearing loss
• Treatment: based on the underlying cause
  • Viral: See “Treatment” section below.
  • Bacterial
    • IV antibiotics PLUS tympanostomy with insertion of tympanostomy tube PLUS glucocorticoids
    • Mastoidectomy (to treat the source of infection in acute otitis media)
  • Autoimmune: corticosteroids

Labyrinthitis can be distinguished from vestibular neuritis based on the presence of hearing loss.

See “Approach to vertigo” for details on clinical evaluation, targeted testing (e.g., HINTS examination), and neuroimaging for patients with undifferentiated acute vestibular syndrome.

• Vestibular neuritis is a clinical diagnosis.
• Perform a complete otoneurological examination to distinguish between peripheral and central vertigo in all patients.
• Obtain urgent neuroimaging if clinical evaluation suggests central vertigo and in patients with risk factors for ischemic stroke.
• Viral testing (culture or serology) is not routinely recommended ^[1]
• See also “Diagnostic testing for vertigo” for information on additional investigations for causes of peripheral vertigo ,e.g., audiometry and caloric testing.

Hospital admission may be necessary in patients with severe symptoms or if there is any concern for a central etiology of symptoms.

Pharmacotherapy

Therapy is primarily supportive; see “Management of peripheral vertigo” for more information.

• Antiemetics and vestibular suppressants: only indicated in the acute setting.
• Corticosteroids (e.g., prednisone ) ^[12]
  • Not routinely recommended ^[13]
  • There is evidence they improve recovery at the one-month mark, but long-term benefits are uncertain. ^[14]
  • If considered , they should be started within 72 hours of symptom onset. ^[15]
• Antiviral therapy: not routinely recommended ^[4][15]

Other therapies ^[16]

• Vestibular rehabilitation therapy: facilitates central vestibular compensation and accelerates recovery.
• Interventional therapy
  • Overview: reduce or eliminate sensory information output to the brain to allow for central compensation
  • Indication: consider in patients with refractory symptoms
  • Procedures
    • Chemical labyrinthectomy: transtympanic gentamicin infusion ^[17]
    • Surgery: vestibular neurectomy or labyrinthectomy

• BPPV: In about 10–15% of patients, BPPV develops within weeks of vestibular neuritis onset. ^[2]
• Persistent postural perceptual dizziness: fear of falling or unsteadiness without actual falls or vestibular dysfunction to explain the symptoms ^[2]

We list the most important complications. The selection is not exhaustive.

• Spontaneous recovery or central vestibular compensation and habituation within a few weeks is common (good prognosis). ^[18][19][20]
  • Vertigo symptoms usually improve within 24–48 hours of onset in most patients. ^[2]
  • Vestibular rehabilitation can speed up recovery. ^[2]
• Recurrence is uncommon (2–11%). ^[2]