Pathophysiology

Vestibular neuritis is most commonly caused by viral inflam­mation of the vestibular nerve, but otitis media is another possible cause. Increasing evidence suggests an association with latent herpes simplex virus type 1 (HSV-1) infection of the vestibular ganglia.³ Inflammation of the eighth cranial nerve causes the sensation of vertigo. Acute suppurative labyrinthitis, an uncommon bacterial infection of the inner ear, is more serious and may be a complication of otitis media or meningitis.⁴ Vestibular neuritis may also be caused by irritation from chemical products associated with acute or chronic otitis media.

Clinical Presentation

Patients with vestibular neuritis complain of severe vertigo, nausea, and vomiting aggravated by head movement. Tinnitus may be present, but hearing remains intact.³ The most severe symptoms of vertigo usually subside within 48 to 72 hours, but they can last 4 or 5 days. Although most episodes resolve spontaneously, up to half of patients will continue to experience dizziness and disequilibrium for many months.² Albeit not life-threatening, these symptoms can cause significant emotional and social stress for patients.

The history should include current medication use; history of head trauma; and duration, episodic nature, and severity of the vertigo. Past medical history and recent infection, particularly in the respiratory tract, should be elicited. Precipitating or aggravating factors, including cough, sneeze, or change in head position, and associated symptoms should be ascertained to help determine the cause of the vertigo.

Physical Examination

A thorough ear, nose, and throat examination and a careful neurologic evaluation, including balance testing (Romberg test), are recommended. A hearing screen reveals normal hearing.³ Spontaneous nystagmus, horizontal or rotary, is often present with fast phases directed away from the affected ear. The nystagmus may need to be evaluated by use of Frenzel lenses for greater magnification.³ Any abnormal finding on neurologic examination suggests a central cause and should be referred for immediate neurologic evaluation.⁴

Diagnostics

More definitive examinations to test hearing and to assess vertigo may be warranted. If a bacterial cause is suspected, a complete blood count (CBC) with differential may be helpful. If a tumor is suspected, magnetic resonance imaging (MRI) or a computed tomography (CT) scan is indicated.

Differential Diagnosis

Additional causes of peripheral vertigo and central vertigo must be considered. Benign paroxysmal positional vertigo (BPPV) (see Chapter 194) is associated with changes in head position, especially when the patient is recumbent. Meniere disease is associated with recurrent episodic vertigo, fluctuating hearing loss, and tinnitus.³ Migrainous vertigo may occur in patients with a history of migraines.⁵ Ramsay Hunt syndrome, caused by herpes zoster, includes hearing loss, facial palsy, and vertigo.⁶ Central causes of vertigo, such as cerebellar disorders, are less common but potentially life-threatening.⁴ Multiple sclerosis, head trauma, barotrauma, and toxins such as drugs and alcohol can also cause similar symptoms. Additional information about vertigo can be found in Chapter 194.

Treatment focuses on three goals: (1) alleviating vertigo, nausea, and vomiting, (2) treating the cause of infection, and (3) improving ventral compensation through vestibular exercises.³ Symptomatic relief can be achieved with anticholinergics, antihistamines, long-acting benzodiazepines, or antiemetics. Anticholinergics and antihistamines are first-line agents; benzodiazepines are reserved for patients who cannot take drugs with anticholinergic effects. Meclizine, 25 to 50 mg every 6 hours, is commonly used and acceptable in pregnancy. Antiemetics may be added during an acute episode to relieve vomiting.⁷ These medications should be stopped after 3 days because continuing them may hamper vestibular recovery.⁷ The use of antivirals as monotherapy has not proven effective and is typically not recommended.³ Some studies report improvement of symptoms with corticosteroids; however, more recent studies have shown little benefit. Despite conflicting evidence, it is reasonable to begin steroid therapy during the acute phase of vertigo.³ Methylprednisolone can be given once daily for 22 days beginning with diagnosis, beginning with a 100-mg dose and gradually tapering down every 3 days. Once the severe symptoms have passed, patients may benefit from vestibular enhancement exercises, which can be obtained through physical therapy services.^3,7

Life Span Considerations

Medications for symptomatic relief of vestibular neuritis can cause drowsiness and sedation. In older adults, lower doses of medications (e.g., 12.5 mg of meclizine or less) should be considered for control of sedation.

Complications

Sensorineural hearing loss can occur after resolution of inner ear inflammation. In older adults especially, vertigo may increase the risk of falls.

Indications for Referral or Hospitalization

Consultation with an otolaryngologist is indicated if the diagnosis is unclear, the bacterial infection is severe, or symptoms do not resolve within 4 to 6 weeks. Associated suppurative otitis media or meningitis also necessitates referral. Severe dehydration indicates a need for intravenous rehydration and possible hospitalization.

Patient and Family Education

The provision of information about the disorder and reassurances will be helpful to patients and families. The importance of slowly changing positions should be discussed. In addition, adequate hydration and safety should be stressed. Patients, particularly older adults, may require assistance with activities of daily living or a walker or cane during the acute phase of the illness. Patients should avoid driving and operating heavy equipment while taking sedatives or antihistamines.

Because the disorder usually resolves within 4 to 6 weeks, patients should understand the importance of notifying the health care provider if the symptoms continue or increase in severity. Follow-up evaluation should be scheduled to reassess the patient and to ensure that the vertigo is resolving.

Pathophysiology

Meniere disease involves excess fluid and pressure in the labyrinth of the inner ear that episodically distends the structures of the labyrinth and damages the vestibular and cochlear hair cells. The exact cause remains unknown; however, the majority of cases are likely caused by viral infections or immune system–mediated mechanisms.⁸ Up to one third of all cases seem to originate from an autoimmune process. Less common potential causes include tumors and trauma.