What is labyrinthitis?
Inflammatory condition caused by bacteria or viruses that affects the inner ear, which consists of the cochlea and vestibular system.
What are the risk factors for labrythinitis?
- Viral infections
- Chronic suppurative otitis media
- Acute otitis media
- Cholesteatoma
- Meningitis
- Inner ear malformations
Briefly describe the cause of viral labrythinitis
- Viral labyrinthitis is typically associated with a preceding upper respiratory tract infection.
- Viral agents include varicella zoster virus, cytomegalovirus, mumps, measles, rubella, and HIV.
Briefly describe the cause of bacterial labryinitis
- Bacterial labyrinthitis is associated with acute or chronic otitis media, meningitis, and cholesteatoma (a collection of epidermal and connective tissues within the middle ear). Unlike viral labyrinthitis, the bacterial form may affect both ears simultaneously.
- Bacterial causes: Treponema pallidum, Haemophilus influenzae, Streptococcus species, Staphylococcus species and Neisseria meningitidis.
What investigations should be ordered for labyrinthitis?
- Audiogram
- Rhinne’s test
- Weber’s test
Why investigate using an audiogram? And what may this show?
- Useful to document the extent of hearing loss and to confirm the affected ear.
- Sensorineural hearing loss.
Why investigate using Rhinne’s? And what may this test show?
- Determine whether any hearing loss is secondary to middle ear (conductive hearing loss) or inner ear/eighth cranial nerve (sensorineural hearing loss) causes.
- Sensorineural hearing loss.
Briefly describe Rhinne’s test
The base of a 512-Hz tuning fork is placed on the mastoid and the patient indicates when he or she longer hears the sound. Once the sound is no longer audible, the tuning fork is placed in front of the ear and the patient is asked whether he or she hears the sound. If the sound is louder when the tuning fork is on the mastoid, then the patient has a conductive hearing loss. If the sound is louder with the fork in front of the ear, the hearing loss is sensorineural or normal.
Why investigate using Weber’s? And what may this show?
- Localise the affected ear and determine whether the hearing loss is sensorineural or conductive.
- Sensorineural hearing loss.
Briefly describe Weber’s test
Examination with a Weber 512-Hz tuning fork (placing the tuning fork on the forehead or maxillary teeth and asking the patient to state in which ear the sound was louder). The sound will be perceived in the affected ear when a unilateral conductive hearing loss is present or in the unaffected ear when there is a unilateral sensorineural hearing loss.
Briefly describe the treatment for viral labyrinthitis
- Vestibular suppressant and anti-emetic
- Corticosteroid (if accompanied by sensorineural hearing loss)
Briefly describe the treatment for bacterial labyrinthitis
- Treatment of underlying condition e.g. acute otitis media, secondary to meningitis
- Vestibular anti-suppressant and anti-emetic
Give examples of drugs that can be used as vestibular suppressant and anti-emetics
- Antihistamines with anticholinergic properties (e.g., promethazine, cyclizine, dimenhydrinate)
- Anti-emetics (e.g., prochlorperazine, metoclopramide, ondansetron)
What complications are associated with labyrinthitis?
- Cochlear ossification
- Hearing loss
- Bilateral vestibular hypo-function
What differentials should be considered in labyrinthitis?
- Vestibular neuritis
- Benign paroxymal positional vertigo (BPPV)
- Meniere’s disease
How does labyrinthitis and vestibular neuritis differ?
- Signs and symptoms: similar presentation to labyrinthitis but no hearing loss. Vertigo is exacerbated by change in head position with respect to gravity.
- Investigations: normal audiogram.
How does labyrinthitis and benign paroxymal positional vertigo differ?
- Signs and symptoms: similar presentation to labyrinthitis but no hearing loss.
- Investigations: normal audiogram and a positive Dix-Hallpike’s test (rotatory nystagmus and reproduction of symptoms).
How does labyrinthitis and Meniere’s disease differ?
- Signs and symptoms: fluctuating hearing loss, low-pitch tinnitus, low-frequency hearing loss, repeated episodes of vertigo.
- Investigations: complete audiological evaluation. Includes pure-tone air and bone conduction, speech audiometry, tympanometry, and otoacoustic emissions. Typically reveals sensorineural hearing loss mainly in the low frequencies, although other configurations of hearing losses may be present.
