Infections of the Labyrinth | Labyrinthitis | PPT
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Infections of the Labyrinth
Infections of the Labyrinth
Labyrinthitis: inflammation of the inner ear
Multiple etiologies: infectious, autoimmune, systemic disease, trauma
Infectious agents include bacteria, viruses, fungus and protozoa.
Vestibular manifestations (vertigo)
Cochlear manifestations (hearing loss)
Infection usually occurs by one of three routes:
From the meninges
From the middle ear space
Meningogenic: through the IAC, cochlear aqueduct, both (bilateral)
Tympanogenic: extension of infection from the middle ear, mastoid cells or petrous apex-most common through the round or oval window (unilateral)
Hematogenous: least common
Two types of labyrinthitis associated with bacterial infections:
Toxic Labyrinthitis: results from a sterile inflammation of the inner ear following an acute or chronic otitis media or early bacteria meningitis.
Toxins penetrate the round window, IAC, or cochlear aqueduct and cause an inflammatory reaction in the perilymph space.
Toxic Labyrinthitis produces mild high frequency hearing loss or mild vestibular dysfunction
Treatment: Antibiotics for precipitating otitis, possible myringotomy.
Suppurative Labyrinthitis: direct invasion of the inner ear by bacteria.
From otitis or meningitis
Suppurative Labyrinthitis: 4 stages
Serous or irritative: production of Ig rich exudates in the perilymph
Acute or purulent: bacterial and leukocyte invasion of the perilymphatic scala-end organ necrosis
Fibrous or latent: proliferation of fibroblasts and granulation tissue in the perilymph
Osseous or sclerotic: new bone deposition throughout the involved labyrinth
Purulent Labyrinthitis: medical emergency
Meningitis or Otitis symptoms
Hospitalization, hydration, vestibular suppressants and iv antibiotics
H. influenza B, N. meningitidis, S. pneumoniae
Hib vaccine: 55% decrease in cases
Pneumococcus now predominant org.
Postmeningitis hearing loss 10-20%
Bilateral, severe to profound, permanent
Diagnosis by FTA-ABS and confirmed by Western Blot.
Congenital or Acquired
Acquired: SNHL during secondary or tertiary
Early: high fetal and infant mortality
Late SNHL+/- vestibular symptoms
Systemic viral illness
Isolated involvement of inner ear
Most common congenital infection in US
Most common infectious cause of congenital deafness
Low birth weight, jaundice, hepatosplenomegaly, petechiae, microcephaly and psychomotor retardation.
65% w SNHL-bilateral, severe to profound
Diagnosis by isolating virus from urine during first few weeks of life.
Virus isolation form cord blood
No treatment: acyclovir may decrease amount of shedding, gancyclovir & foscarnet not approved during pregnancy.
Decline due to vaccine
Congenital rubella: cataracts, heart malformations and SNHL, others
Dx by viral culture
No treatment; prevention only
Parotitis, orchitis, meningoencephalitis, and in 0.05% of cases-hearing loss.
Hearing loss at end of first week of parotitis, unilateral and range from mild, high frequency SNHL to profound SNHL.
Vestibular involvement is uncommon
Systemic illness w rash, conjunctivitis, and mucosal Koplik spots.
Measles induced hearing loss is 1/1000 cases
Measles less common 2nd to vaccine
Encephalitis in 0.1% of cases w overall mortality rate of 15%, with 25% of survivors with SNHL.
SNHL seen in conjunction with rash.
Varies from mild to profound HF SNHL
Unilateral or bilateral
70% have vestibular losses also
Primary vzv=chicken pox
HL w chicken pox = CHL 2nd to MEE
Herpes zoster oticus= Ramsay Hunt syndrome, reactivation from the geniculate ganglion of CN VII. Painful vesicles.
1/3 have auditory or vestibular symptoms-HFHL, hyperacusis, tinnitus, vertigo
Labyrinthine infection by:
Reactivation in the spiral ganglion=SSNHL
Extension of the meningoencephalitis along CN VIII to the labyrinth=acquired SNHL
HSV-1 &2 can infect labyrinth. Animal models of ISSNHL. ??Humans.
Neuroepithelial cells of the cochlea, utricle, saccule, and semicircular canals infected with HSV
Circumstantial evidence only
Human Immunodeficiency virus
Auditory and vestibular complaints rare in AIDS patients
Some w hearing loss, tinnitus and vertigo
Thought to be result of opportunistic infections (CMV, HSV), ototoxic drugs, neoplasm of inner ear.
Fungal labyrinthitis is exceedingly rare outside the context of host immunocompromise.
High risk: diabetics, chemo therapy, organ transplant recipients, AIDS patients
Agents include Mucor, Cryptococcus, Candida, Aspergillus, and Blastomyces
Hearing loss is severe and permanent
Toxoplama gondii most common
Acquired infection usually asymptomatic
Congenital infection may lead to severe malformations of fetus
Triad of chorioretinitis, hydrocephalus, intracranial calcifications
May also have microcephaly, cataracts, micropthalmia, jaundice, and hsm.
3000 cases annually
75% asymptomatic at birth
15% ocular problems
10% severe malformations
85% of symptomatic infants at birth will later develop decreasing visual acuity, decreased intellectual function, hearing loss or precocious puberty.
Screening test to determine fetal infection
PCR analysis of amniotic fluid
Quantitative maternal/fetal IgG analysis of cord blood
Prenatal tx reduces both transmission and severity of illness in the fetus
Combination of pyrimethamine and sulfonamide
Neonates with documented infection should be given tx for 1st year of life + folic acid supplements
Pts present with only auditory dysfunction-acute cochlear labyrinthitis
Pts present with only vestibular dysfunction-acute vestibular labyrinthitis
Both-acute cochleovestibular labyrinthitis
Acute cochlear labyrinthitis, aka idiopathic sudden sensory neural hearing loss (ISSNHL)
Defined as minimum of 30dB deficit in three contiguous frequencies over a period of less than 3 days in a previously healthy person.
3 pathologic theories: viral infection, vascular phenomenon, intralabyrinthine membrane rupture.
Much circumstantial evidence of viral etiology
Acute cochlear labyrinthitis
30-70% have complete recovery of hearing.
Prognosis related to age, time from onset to presentation, type of audiogram, presence of vestibular symptoms
Seen within 10 days
Started on steroids within 10 days
Acute vestibular labyrinthitis, aka vestibular neuritis
Defined as sudden unilateral vestibular weakness in the absence of concomitant auditory or CNS dysfunction in a previously healthy person
Acute vestibular labyrinthitis
An acute, unilateral, peripheral vestibular disorder w/o associated hearing loss
Occurrence predominantly in middle age
A single episode of severe, prolonged vertigo
Decreased caloric response in the involved ear.
Complete subsidence of the symptoms within 6 months
Acute vestibular labyrinthitis
Treatment is supportive and includes hydration, antiemetics, and vestibular suppressants.
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