Sudden Sensorineural Hearing Loss

1. See Also
   1. Sensorineural Hearing Loss
   2. Hearing Loss
   3. Conductive Hearing Loss
   4. Hearing Impairment Severity Scale
2. Epidemiology
   1. Incidence: 5-20 per 100,000 people annually aged 40-60 years old
3. 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
4. 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
5. Exam
   1. See Hearing Loss
   2. See Hearing Impairment Severity Scale
6. Differential Diagnosis
   1. Conductive Hearing Loss
7. 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
8. Diagnosis: Audiogram
   1. Rapid loss of hearing within a 72 hour period
   2. Hearing Loss of 30 DB in at least 3 connected frequencies
9. 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
10. 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
          1. Typical adult dose: 60 mg for 5 days and then taper off over 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
11. Prognosis
    1. Spontaneous recovery in up to 70% of idiopathic cases
12. 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]