Background: Labyrinthitis is an inflammation or dysfunction of the vestibular labyrinth, which is a system of intercommunicating cavities and canals in the inner ear. The syndrome is defined by the acute onset of vertigo that commonly is associated with head or body movement. Nausea, vomiting, or malaise often accompanies the vertigo.

Vertigo is the subjective sensation of environmental movement that may be experienced as a mild subjective instability of the surroundings or, in its most severe form, as a spinning sensation. Vertigo may be experienced and described anywhere between these 2 extremes. Vertigo syndromes have many synonyms, including labyrinthitis, benign positional vertigo, cupulolithiasis, and vestibular neuronitis.

Pathophysiology: The pathophysiology of this syndrome is not completely understood. However, a dysfunction of the vestibular apparatus clearly is present when labyrinthitis occurs.

Theories involve lesions in the otolith organs, degeneration of the utricular macula, or lesions in the posterior semicircular canal. The cupulolithiasis theory suggests that otoconia, which are formed by a dysfunctional utricular macula, settle on the cupula of the posterior semicircular canal, causing aberrant stimulation of the vestibular system.

A more popular theory is that of canalithiasis, as well outlined by Hall in 1979. This theory postulates that free-floating otoconial debris produces pressure in the semicircular canal, causing deflection of the cupula. This deflection results in a transient attack of vertigo.

Many cases of labyrinthitis are associated with systemic or viral-like illnesses. Suppurative or bacterial labyrinthitis is rare, but it should be considered in patients with acute or chronic otitis media. Cases are reported in association with meningitis, but the presentation of the meningitis often overwhelms the vestibular symptoms.

Frequency:
 

• In the US: In 1987, a large study of 240 patients with benign paroxysmal vertigo was published and revealed the following etiologies:

  Idiopathic - 49% (118 patients)

  Posttraumatic - 18% (43 patients)

  Viral neurolabyrinthitis -15% (37 patients)

  Miscellaneous - 18% (42 patients)

  The miscellaneous etiologies in this study included vertebrobasilar ischemia, Ménière disease, postsurgical ototoxicity, luetic labyrinthitis, and chronic otomastoiditis.

  Other studies have shown a lower frequency of idiopathic cases. A specific diagnosis is usually possible in cases of recurrent acute and chronic vertigo. Benign paroxysmal vertigo and Ménière disease are the most frequent causes of peripheral vertigo.

Mortality/Morbidity:

• In the vast majority of patients with labyrinthitis syndrome, the acute episode is self-limited and lasts anywhere from days to weeks.

• Spontaneous recovery is the rule. However, recurrences are common, especially in the first 5 years following the first episode. In rare cases, the episode can last months or even years.

   

• Death is not associated with the syndrome unless an underlying condition (eg, brainstem tumor, vertebrobasilar ischemia) is present.

• Loss of vestibular function and/or hearing as a result of bacterial labyrinthitis is typically severe and permanent.

Sex: Combined data from various studies reflect that females with labyrinthitis outnumber males with labyrinthitis (female-to-male ratio 1.5-2:1).

History: Although the vast majority of cases of labyrinthitis are self-limited, a minority of patients can have a more chronic and prolonged course. Patients express difficulties involving vertigo and hearing.

• Patients with the labyrinthitis syndrome typically develop brief (<1 min) episodes of vertigo that are associated with head and/or body position changes. Examples of such movement include the following:

• Turning over in bed

• Reaching and looking above the head (ie, top shelf vertigo)

• Rising from a bed or chair (ie, matutinal vertigo)

• At times, the vertigo may be persistent and severe.

• Acute episodes of position-sensitive vertigo may have characteristics including the following:

• Nausea, vomiting, and malaise

• May occur following head trauma

• May be associated with a recent viral illness (eg, cold, flu)

• A brief change in hearing also can be experienced, although these episodes rarely last more than a few seconds.

• Tinnitus and a subjective change in hearing are symptoms most commonly reported.

• Ask about a prior history of hearing loss or dysfunction.

• Hearing loss does not occur with benign paroxysmal vertigo or vestibular neuronitis. Hearing loss does occur with infectious labyrinthitis and Ménière disease and is seen frequently with ototoxicity and autoimmune labyrinthitis.

• Hearing

• Perform a gross testing of hearing with a tuning fork (256 Hz preferred, although a 512 Hz also can be used).

• A sufficient screen may entail gently rubbing the fingers together and measuring the farthest distance from which the patient can hear this stimulus while occluding the other ear.

• Visualize the tympanic membranes to exclude otitis media and other associated middle ear problems.

• Note any decrease in hearing or asymmetry of hearing, because these symptoms suggest a problem other than labyrinthitis (although hearing loss does not in and of itself exclude the diagnosis of labyrinthitis).

• Cranial nerves

• Give particular attention to the cranial nerve examination.

• Any abnormalities in the neurological examination that cannot be attributed to the vestibular system may point toward a different diagnosis that would warrant a more substantial workup and a different treatment strategy.

• Vestibular maneuvers may be helpful in diagnosis of the syndrome.

• Nylen-Bárány maneuver: While the patient is seated at the end of the examining table, quickly lay back and carefully hyperextend the patient onto the back, while support is provided to the head. First, turn the head toward one shoulder. Repeat the maneuver; however, the second time, turn the head toward the other shoulder.

• Hallpike maneuver: While the patient is seated in the middle of the examination table, carefully provide support to the head and neck while quickly laying the patient on one side and then the other.

• Repeat the maneuvers several times in a period of 5-10 minutes, as tolerated by the patient.

• Interpretation of these vestibular maneuvers is identical.

• Note the reproducibility of the vestibular symptoms, including vertigo, nausea, and malaise.

• Typically with labyrinthine disorders, these symptoms are worse with the head in a particular position.

• Note fatigue and extinction of the vestibular symptoms and whether the severity of the symptoms decreases with the successive repetition of the maneuvers.

• Note nystagmus in primary gaze or gaze-invoked nystagmus. Most commonly, the nystagmus is either horizontal or rotatory. Observe nystagmus onset and any latent period between the completion of the maneuver and the onset of the nystagmus. Note the length of the latent period in seconds.

• Interpretation of these findings of the vestibular maneuvers is of critical importance. If the localization of the vestibular dysfunction is peripheral, it is usually benign; a central location can indicate a more serious prognosis.

• Peripheral vestibular dysfunction is associated with (1) a short latency between the change in position and the vertigo, nausea, and malaise symptomatology; (2) a latency of several seconds after the change in position and before the onset of nystagmus; and (3) fatigue with habituation of the nystagmus and with the vertigo/nausea/malaise symptoms associated with repeated maneuvers.

• Central vestibular lesions are associated with immediate onset (no latency) of nystagmus and minimal symptoms of vertigo, nausea, or malaise. The nystagmus does not fatigue or habituate with repetitive vestibular maneuvers.

   

• The assessment of nystagmus in the conscious patient is problematic since visual fixation suppresses the nystagmus.

   

• These maneuvers are helpful if they are positive, but many results are equivocal.

Causes: Physiologically, a mismatch of vestibular, visual, and somatosensory systems is present. This mismatch is triggered by an external stimulus, such as a stop after turning, a change in altitude, or motion/height sickness. A lesion within vestibular pathways (ie, inner ear to cerebral cortex) causes this imbalance.

• In 1987, a large study of 240 patients with benign paroxysmal vertigo was published and revealed that 49% (118 patients) had an idiopathic etiology, 18% (43 patients) had a posttraumatic etiology, 15% (37 patients) had a viral neurolabyrinthitis etiology, and 18% (42 patients) had a miscellaneous etiology. The miscellaneous etiologies in this study included vertebrobasilar ischemia, Ménière disease, postsurgical ototoxicity, luetic labyrinthitis, and chronic otomastoiditis.

• The most common cause of the labyrinthitis syndrome is idiopathic.

• Posttraumatic and viral neurolabyrinthitis are the next most common causes of this disorder.

• The following variety of miscellaneous conditions also can be associated with this syndrome:

• Vertebrobasilar ischemia

• Ménière disease

• Postsurgical ototoxicity

• Luetic labyrinthitis

• Chronic otomastoiditis

• Tumors

• Vasculitis

• Ototoxic drugs

• Head injury

• Vestibular neuronitis

• Risk factors associated with labyrinthitis include the following:

• Trauma

• Drug ingestion

• Predisposing viral infection

• Cardiovascular disease; cerebrovascular disease

• Perilymphatic fistula