Sensorineural Hearing Loss


Sensorineural Hearing Loss, Perceptive Hearing Loss, Sensorineural Deafness

  • Definitions
  1. Sensorineural Hearing Loss
    1. Disorder of converting mechanical sounds to neuroelectric sound in the inner ear or auditory nerve
  • Epidemiology
  1. Age of onset over 40 years old
  • Causes
  1. See Sudden Sensorineural Hearing Loss
  2. Presbycusis related to aging (often bilateral)
    1. Most common cause of Sensorineural Hearing Loss
  3. Noise Induced Hearing Loss (bilateral)
    1. Acute exposure to sudden loud noise >130 dB noise
    2. Chronic exposures to loud noise >85 dB
  4. Cranial Nerve 8 disease
    1. Meniere's Disease (associated with Tinnitus and Vertigo)
    2. Acoustic Neuroma (unilateral)
  5. Hematologic from vascular sludging and Hypoxia
    1. Polycythemia Vera
    2. Sickle Cell Anemia
    3. Leukemia
    4. Hypercoagulable states
  6. Microvascular disease
    1. Diabetes Mellitus
    2. Hyperlipidemia
  7. Ototoxic Medications (bilateral)
    1. See Ototoxic Hearing Loss
  8. Infectious Causes
    1. Tertiary Syphilis
    2. Lyme Disease
    3. Acute Labyrinthitis (Viral Labyrinthitis)
      1. Mumps is most common cause
    4. Meningitis
    5. Otitis Media complication
  9. Endocrine Disease
    1. Hypothyroidism
  10. Autoimmune Hearing Loss
  11. Congenital Deafness
  12. Trauma (e.g. Traumatic Brain Injury, other head and neck Trauma)
    1. Temporal BoneFracture involving Cochlea or vestibule
    2. Perilymph fistula
      1. Round window or oval window rupture with leak
      2. Caused by Trauma, lifting, straining, coughing
  • 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. Hearing Loss
    1. See Hearing Impairment Severity Scale
    2. Frequently ask others to repeat what they have said
    3. Impaired word understanding often present
    4. Loud patient's voice
    5. Hearing difficult in noisy environments
  • 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
  4. Hum Test
    1. Sensorineural Hearing Loss will localize to the unaffected ear
    2. Contrast with Conductive Hearing Loss which will localize to the affected ear
  • 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
  • Management
  1. Formal audiology testing
  2. Acute Hearing Loss (within 3 days)
    1. See Sudden Sensorineural Hearing Loss
    2. Urgent evaluation needed for 30 db loss
    3. High dose Steroids (1 mg/kg/d) (uncertain efficacy)
    4. Carbogen Inhalation (5% CO2 and 95% Oxygen)
      1. May increase Cochlear Blood Flow by vasodilation
      2. Duration determined by serial Audiograms
    5. Otolaryngology evaluation
  3. Chronic
    1. See Hearing Aid
  • Course
  1. Often no etiology identified
  2. May resolve spontaneously