II. Epidemiology

  1. Age of onset over 40 years old

III. Causes

  1. See Sudden Sensorineural Hearing Loss
  2. Presbycusis related to aging (bilateral)
  3. Noise induced Hearing Loss (bilateral)
  4. Cranial Nerve 8 disease
    1. Meniere's Disease
    2. Acoustic Neuroma
  5. Viral
    1. Mumps
  6. Hematologic from vascular sludging and Hypoxia
    1. Polycythemia Vera
    2. Sickle Cell Anemia
    3. Leukemia
    4. Hypercoagulable states
  7. Microvascular disease
    1. Diabetes Mellitus
    2. Hyperlipidemia
  8. Ototoxic Medications (bilateral)
  9. Infectious Causes
    1. Tertiary Syphilis
    2. Lyme Disease
  10. Endocrine Disease
    1. Hypothyroidism
  11. Autoimmune Hearing Loss
  12. Congenital deafness
  13. Trauma
    1. Temporal Bone Fracture involving Cochlea or vestibule
    2. Perilymph fistula
      1. Round window or oval window rupture with leak
      2. Caused by Trauma, lifting, straining, coughing

IV. Symptoms

  1. Tinnitus
    1. Ringing, buzzing, humming, hissing, "crickets in ears"
    2. Occurs early in Hearing Loss course
  2. Pain with loud noise exposure
  3. Frequently ask others to repeat what they have said
  4. Impaired word understanding often present
  5. Loud patient's voice
  6. Hearing difficult in noisy environments

V. Signs

  1. Otoscopy
    1. Ear Canal and TM are normal
  2. Weber Test (Tuning Fork at Midline) Abnormal
    1. Sound radiates to ear with less sensorineural loss
  3. Rinne Test (Tuning Fork on Mastoid) Abnormal
    1. Both air conduction and bone conduction reduced

VII. Imaging

  1. MRI Head at Internal Auditory Canal (IAC)
    1. Gold standard to evaluate for Acoustic Neuroma
    2. Evaluates for inflammation such as due to Herpes Zoster Oticus
    3. Vascular lesions may be evident
  2. MRA head
    1. Indicated if vascular lesion is suspected
  3. CT Temporal Bone
    1. Evaluates infectious causes (e.g. Mastoiditis, Cholesteatoma)
    2. Evaluates bone anatomy (ossicles and Cochlea, vestibular aqueduct swelling, Fractures)
    3. Can also identify Acoustic Neuroma and vascular lesions but MRI is preferred

VIII. Management

  1. Formal audiology testing
  2. Acute Hearing Loss (within 3 days)
    1. Urgent evaluation needed for 30 db loss
    2. High dose Steroids (1 mg/kg/d) (uncertain efficacy)
    3. Carbogen Inhalation (5% CO2 and 95% Oxygen)
      1. May increase Cochlear blood flow by vasodilation
      2. Duration determined by serial Audiograms
    4. Otolaryngology evaluation
  3. Chronic
    1. See Hearing Aid

IX. Course

  1. Often no etiology identified
  2. May resolve spontaneously

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