Disorders of the peripheral auditory system


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Disorders of the peripheral auditory system

  1. 1. Ozarks Technical Community College HIS 120 Disorders of the Peripheral Auditory System
  2. 2. Disorders of the Outer & Middle Ear  Causes a conductive hearing loss (CHL)  On the audiogram, you would find normal bone conduction thresholds and abnormal air conduction thresholds  Tympanograms (test of middle ear function) will be abnormal
  3. 3. Conductive HL in Right Ear
  4. 4. Abnormal Tympanograms Type B=flat Type C=negative pressure
  5. 5. Abnormal Tympanograms Type As=stiff, hypocompliant Type AD=flaccid, hypercompliant
  6. 6. Outer Ear Pathologies  Anotia o absence of the outer ear  Microtia o malformation of the outer ear  Wax build-up  Otitis Externa o aka swimmer’s ear or outer ear infection (bacterial)  Atresia o absent or closed earcanal  Stenosis o narrowing of EAC  Otomycosis o fungal infection of EAC  Exostoses o bony growth in EAC, common in cold water swimmers  Osteoma o bony tumor in EAC
  7. 7. Tympanic Membrane Pathologies  Myringitis o inflammation of TM  Tympanosclerosis o thickening and scarring of the TM  Perforation o hole or tear in the TM o May be caused by fluid pressure due to otitis media, barotrauma (rapid pressure change due to flying or scuba diving), or self-inflicted (q-tip use)
  8. 8. Middle Ear Pathologies  Otitis media (OM)=middle ear infection  Otitis media with effusion (fluid)  May be acute (sudden onset) or chronic (long-lasting)  Eustachian tube dysfunction  malfunction of Eustachian tube  Causes retraction of TM and popping, crackling, pressure, pain  Patulous Eustachian tube  Eustachian tube is stuck open (patent)  Autophony, hearing one’s own voice in head, is common complaint  Otosclerosis  Bony growth over stapes footplate and fixation to oval window  Ossicular chain discontinuity  Loss of connection between the ossicles; usually due to head injury
  9. 9. Treatment for Conductive HL  Medical  Antibiotic eardrops, oral antibiotics for bacterial infections  Surgical  Myringotomy (incision in TM), pressure-equalization tubes, ossicular repair, stapedectomy (removal of stapes and prosthesis placement)  Amplification  CHL is very easy to fit with a hearing aid(s)  Because the sensory cells of the cochlea are healthy, CHL only requires amplification to power through the middle ear pathology. Once the sound gets past the middle ear problem, it is clearly transmitted through the remainder of the auditory system with ease.
  10. 10. Disorders of the Inner Ear  Results in a (primarily) sensorineural hearing loss (SNHL)  On the audiogram, you would find abnormal bone conduction and air conduction thresholds  Tympanograms (test of middle ear function) will usually be normal
  11. 11. Bilateral SNHL
  12. 12. Normal Tympanogram  Tests middle ear function = eardrum, ossicles, eustachian tube  Measures changes in the movement of the eardrum Type A=normal
  13. 13. Inner Ear Pathologies Presbycusis  Age-related hearing loss; effects the high frequencies first  Noise-Induced Hearing Loss (NIHL)  Exactly like it sounds; dependent on intensity, duration, and type of noise exposure, classic “noise notch” seen from 3 to 6 kHz, with recovery at 8 kHz  Meniere’s disease  Overacummulation of endolymph in the cochlea; characterized by attacks of vertigo, tinnitus (roaring), low- frequency SNHL (usually unilateral), nausea/vomiting  Ototoxicity  High-frequency SNHL due to damaging effects of certain drugs (most notably aminoglycoside antibiotics and platinum-based chemo drugs)  Perilymph fistula  Hole (fistula) at the oval window, in which perilymph leaks into middle ear. Fluctuating HL (SNHL or Mixed HL) and dizziness common.  Superior Semicircular Canal Dehiscence  Hole or thinning of the bony lining of the superior SCC; symptoms: fullness, autophony, dizziness with/sensitivity to
  14. 14. A note about sudden hearing loss  Sudden, idiopathic sensorineural hearing loss is any SNHL that occurs very suddenly with no identifiable cause  Usually unilateral  May be partial or complete loss of hearing  Often accompanied by dizziness and tinnitus  Requires IMMEDIATE medical referral  Do not assume that a patient has wax, an infection, or a broken hearing aid if they call complaining of a sudden inability to hear. If you can’t see them ASAP refer them to their primary doctor or an ENT for a same-day appointment, if possible. Steroid treatment that occurs within the first week of the hearing loss may result in improved/recovered hearing.
  15. 15. Treatment for SNHL  Hearing Aids  Hearing Assistive Technology  Cochlear Implants
  16. 16. Mixed HL in the Right Ear  Mixed hearing loss (MHL) is a combination of sensorineural hearing loss with a conductive HL component  Commonly seen in older adults with presbycusis and middle ear disorder  May be seen in cases of perilymph fistula, head injury, barotrauma Imagefrom: asha.org
  17. 17. Treatment for MHL  Because MHL is a combination of CHL and SNHL, the treatment should also take a combined approach  Always refer to ENT for medical treatment FIRST  Finally, amplify the hearing loss that remains