Sudden Sensorineural Hearing Loss

Aka: Sudden Sensorineural Hearing Loss, Idiopathic Sudden Sensorineural Hearing Loss, SSHNL, Sudden Hearing Loss

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II. Definitions

  1. Sudden Sensorineural Hearing Loss
    1. Rapid loss of Hearing within a 72 hour period
    2. Hearing Loss of 30 DB in at least 3 connected frequencies

III. Epidemiology

  1. Incidence: 5-20 per 100,000 people annually aged 40-60 years old

IV. Precautions

  1. Sudden Sensorineural Hearing Loss is an ENT Emergency requiring urgent evaluation and management

V. Causes

  1. See Sensorineural Hearing Loss
  2. Background
    1. Idiopathic in 80-90% of cases
    2. Significant underlying pathology identified in 16% of cases
  3. Most common causes
    1. Autoimmune inner ear process
    2. Viral Infection
      1. Herpes Zoster Oticus (Ramsay Hunt Syndrome)
        1. Presents with severe Otalgia, ear vessicles, Bell's Palsy
      2. HIV Otitis
        1. Presents with Mastoiditis and other Cranial Nerve neuropathies
    3. Vascular event
      1. Vertebrobasilar Vascular Disease
        1. Presents with bilateral internal auditory artery Occlusion
        2. Brainstem infarct could also cause acute Hearing Loss
      2. Hyperviscosity Syndrome
        1. Presents with Retinopathy, mucous membrane bleeding, neurologic signs, pulmonary signs
  4. Other causes
    1. Neoplasms
      1. Neurofibromatosis II
      2. Bilateral Vestibular Schwannomas
      3. Intravascular Lymphomatosis
      4. Meningioma
      5. Hyperviscosity Syndrome
    2. Toxins
      1. Lead Poisoning
      2. Ototoxic Medications
    3. Infections
      1. Mononucleosis (Epstein-Barr Virus)
      2. Group A Streptococcus
      3. Herpes Simple Virus
      4. Herpes ZosterVirus
      5. HIV Infection
      6. Lyme Disease
      7. Meningitis
      8. Syphilis
    4. Trauma
      1. Head Injury
      2. Barotrauma
      3. Temporal BoneFracture
      4. Acute exposure to sudden loud noise >130 dB noise
    5. Miscellaneous
      1. See Ototoxic Medications
      2. Genetic disorders
      3. Sarcoidosis
      4. Meniere Disease
      5. Pregnancy
      6. Cerebrovascular Accident
      7. Cogan Syndrome
        1. Presents with interstitial Keratitis, Hearing Loss and Vertigo
      8. Mitochondrial disorders (MELAS)
        1. Presents with Mitochondrial Encephalopathy, Lactic Acidosis, Stroke-Like episodes

VI. Symptoms

  1. Sudden onset Hearing Loss
  2. Typically unilateral (bilateral is rare)
  3. Sounds are harsh and distorted
  4. Associated with aural fullness
  5. Vertigo and Ataxia may be present

VII. Exam

  1. See Hearing Loss
  2. See Hearing Impairment Severity Scale
  3. Hum Test (can be performed by nurse phone triage)
    1. Sensorineural Hearing Loss will localize to the unaffected ear (red flag - needs urgent evaluation)
    2. Contrast with Conductive Hearing Loss which will localize to the affected ear (reassuring, routine evaluation)

VIII. Differential Diagnosis

  1. Conductive Hearing Loss

IX. Evaluation

  1. Labs
    1. Not indicated unless dictated by history (e.g. Lyme Titer)
  2. Urgent Audiogram
    1. Perform same day of presentation
    2. Confirms Sensorineural Hearing Loss
    3. Repeat at 6 months from initial Audiogram

X. Diagnosis: Audiogram

  1. Rapid loss of Hearing within a 72 hour period
  2. Hearing Loss of 30 DB in at least 3 connected frequencies

XI. Imaging

  1. Indicated if SSHNL confirmed by Audiogram
  2. MRI with gadolinium
    1. Evaluates retrocochlear lesion (e.g. Schwannoma)
    2. CT Head is not recommended as alternative

XII. Management

  1. Sudden Sensorineural Hearing Loss requires immediate evaluation
    1. Otolaryngology evaluation is recommended within 24 hours
  2. Consider Antiviral Medications
  3. Corticosteroids
    1. Targets inflammatory cell death cascade in Sudden SNHL
    2. Standard of care treatment, but does not appear to significantly improve outcomes
      1. Labus (2010) Laryngoscope 120(9): 1863-71 [PubMed]
    3. Systemic Corticosteroids orally (dosing protocols vary)
      1. Short Adult Protocol: 60 mg for 5 days and then taper off over next 5 days
      2. Harvard Protocol: 60 mg orally daily for 14 days, then taper off over the next 5 days
    4. Intratympanic Corticosteroids by Otolaryngology
      1. Indicated for patients not recovering spotaneously or after initial treatment
    5. Hyperbaric oxygen
      1. May be beneficial in first 3 months
  4. Other measures used
    1. Diuretics
    2. Plasma expanders
    3. Immunosuppressants (in addition to Corticosteroids as above)
  5. Measures without evidence of benefit
    1. Antiviral Agents
      1. Consider only if suspected underlying viral etiology (e.g. HSV, VZV)
      2. Previously 10 days of Valacyclovir, Famciclovir, or Acyclovir was considered
    2. Thrombolytics
    3. Vasodilators
    4. Vasoactive substances
    5. Antioxidants

XIII. Prognosis

  1. Spontaneous recovery in up to 70% of idiopathic cases

XIV. References

  1. Browning (2008) Park Nicollet Primary Care Update, Lecture, St. Louis Park, MN
  2. Orman and Finley (2018) EM:Rap 18(2): 15-6
  3. Michels (2019) Am Fam Physician 100(2): 98-108 [PubMed]
  4. Rauch (2008) N Engl J Med 359(8): 833-40 [PubMed]
  5. Stachler (2012) Otolaryngol Head Neck Surg 146(3 Suppl): S1-35 [PubMed]

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