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Sudden Sensorineural Hearing Loss 

Overview
Sudden sensorineural hearing loss (SSNHL) is classically defined as sensorineural hearing loss that occurs acutely in ≤72 hours, of 30 dB or greater, in at least 3 contiguous frequencies. However, practically, any “significant” loss is usually investigated and treated, as described below. The most common associated symptoms are tinnitus, aural fullness, and hearing loss. When SSNHL presents with vertigo, the constellation of symptoms is termed “labyrinthitis.”  SSNHL harbors a wide differential diagnosis and requires urgent evaluation by an Otolaryngologist. An audiogram is a critical component of the evaluation and will differentiate between SNHL and conductive hearing loss (CHL). Otoscopy can rule out cerumen impaction, effusion, or other causes of CHL. Tuning fork testing can provide gross information on conductive versus sensorineural hearing loss; however, early formal audiometric testing is crucial to more definitively quantify the magnitude and type of hearing loss and provide a baseline to follow. The degree of hearing loss necessary for the diagnosis of SSNHL is not universally agreed upon but hearing loss of 30 dB over 3 consecutive frequencies (compared to the contralateral side if hearing loss is unilateral and no previous audiogram is available for comparison) is frequently quoted. It is important to note that hearing loss below this arbitrary threshold can still be clinically relevant and therefore generally deserves treatment as such. While SSNHL is most commonly idiopathic, this is a diagnosis of exclusion and other etiologies should be ruled out with appropriate work up based upon history and examination findings. Additional etiologies include but are not limited to autoimmune hearing loss, various infections, endolymphatic hydrops (Meniere’s disease), acoustic trauma, retrocochlear pathology such as vestibular schwannoma, microvascular insults, and malingering (see table below). If the patient has no medical contraindications (e.g., uncontrolled diabetes mellitus), treatment with high-dose oral steroids should be strongly considered and administered as soon possible. This is often given in combination with GI ulcer prophylaxis. Intratympanic steroid injections can also be initiated upfront or can be reserved for salvage treatment. Additional salvage therapy of hyperbaric oxygen therapy can be offered depending on severity of hearing loss, logistics, and patient preference. Regardless of improvement in hearing loss, whether spontaneous or post-treatment, all patients should undergo MRI in order to rule out an underlying retrocochlear pathology (e.g., vestibular schwannoma); in patients who cannot undergo MRI for various reasons, auditory brainstem reflexes (ABR) or head CT with contrast can be used, although less sensitive and reliable. If the clinical history and imaging work up is negative, the SSNHL is termed idiopathic, and prognosis generally follows the rule of thirds: 1/3rd of patients will recover completely, 1/3rd will recover to a degree, and 1/3rd will not recover at all. Younger patients, those with less severe hearing loss, low frequency hearing loss, and patients without vertigo have a better prognosis for improvement.

SSNHL Differential Diagnostic Considerations

SSNHL Differential Diagnostic Considerations

Key Supplies for Consultation

  • Otoscope

  • 512-Hertz tuning fork

  • If performing transtympanic steroid injection, will need:

    • Operating microscope

    • Size 4 or 5 ear speculum

    • Phenol and applicator (optional)

    • Size 3 or 5 straight suction

    • Suction source

    • 27-gauge spinal needle

    • 1-2 ml syringe

Management

  • Detailed history:

    • Otologic history (otalgia, otorrhea, aural fullness, tinnitus, vertigo)

    • Time course of hearing loss

    • Previous episodes

    • Recent head trauma

    • Associated eye symptoms (e.g., keratitis seen in Cogan’s disease)

    • New cranial nerve weakness or hypoesthesia

    • History of recent travel or tick exposure

    • Medication use (e.g., narcotics, Sildenafil etc)

    • Past medical history with attention to meningitis, autoimmune conditions or vasculitis, diabetes mellitus, or other possible contributing pathologies

  • Perform a complete head and neck physical exam, with specific attention to the otologic, cranial nerve, and tuning fork exams

  • Obtain audiogram as soon as possible, preferably same day

  • Consider high dose steroids (1mg/kg prednisone max dose 60mg) if no contraindications and initiate as soon as possible. Duration is controversial and an area of ongoing research, but treatment duration typically continues for 5-10 days, and in many cases includes a taper. Should discuss risks and benefits of use with patient before prescribing. Often not prescribed if beyond 4-6 after episode of sudden hearing loss.

  • Laboratory testing is not routinely ordered; consider targeted laboratory testing if suspicion of underlying conditions (e.g., ANA, ESR, RPR/VDRL)

  • Intratympanic steroid injections can also be initiated immediately or can be delayed and used as salvage therapy if oral steroids fail; optimally should be initiated within 2 weeks of hearing loss

    • Position patient in a comfortable position in exam chair

    • Under binocular microscopy, can consider the application of pinpoint phenol to the posterior superior quadrant (note that phenol use is controversial and may increase patient’s risk of long-term tympanic membrane perforation).

    • Consider making a ventilation hole with a 27-gauge needle; this is not required

    • Inject approximately 1 ml of steroid solution (24mg/ml dexamethasone or 40mg/ml Methylprednisolone are two studied concentrations though less concentrated preparations are acceptable if no compounding pharmacy is available) into posterior quadrant using a 27-gauge needle until middle ear is filled

    • Keep patient supine with their head turned to the contralateral ear for at least 10-20 minutes while attempting to avoid swallowing

    • Protocols vary but oftentimes injections are performed weekly for 3 weeks Weekly audiograms prior to each injection can be considered to determine response

  • Consider hyperbaric oxygen treatment within 4-6 weeks of hearing loss depending on severity, patient preference, logistics, response to steroid treatment, ability to equalize pressure in ears (will need PE tubes to tolerate dive pressures if unable to equalize)

  • MRI with gadolinium or high-resolution heavily T2-weighted sequences to rule out retrocochlear pathology in all patient regardless of hearing recovery; consider ABR or CT scan if patient is unable to undergo an MRI

  • Follow up with patient following all treatments and stabilization of hearing, usually around 3 months, and offer rehabilitative measures if residual hearing is not sufficiently useful (conventional or CROS hearing aid, bone-anchored implant, or cochlear implantation)

See the AAO-HNS Clinical Practice Guideline for more detailed discussion of SSNHL.

Example Procedural Note
Procedure: Transtympanic steroid injection
After obtaining informed consent followed by confirmation of the patient’s name, date of birth, and operative laterality, the patient was positioned supine in the exam chair. Visualization of the tympanic membrane (TM) was obtained with binocular microscopy with removal of cerumen as necessary. A 27-gauge needle was then used to create a pinpoint ventilation hole and then 1 ml of 24mg/ml dexamethasone, warmed to body temperature, was then slowly injected into the middle ear with a 27-gauge needle in the posterior quadrant of the tympanic membrane and confirmed to fill the middle ear space. The patient was kept laying in the supine position for 15 minutes. The patient tolerated the procedure well.

 

References

1. Chandrasekhar, S. S., Tsai Do, B. S., Schwartz, S. R., Bontempo, L. J., Faucett, E. A., Finestone, S. A., … Satterfield, L. (2019). Clinical Practice Guideline: Sudden Hearing Loss (Update). Otolaryngology–Head and Neck Surgery, 161(1_suppl), S1–S45. https://doi.org/10.1177/0194599819859885

2. Le Prell, C.G. (2020). Sensorineural Hearing Loss in Adults. In Flint, P.W., et al (Eds.), Cummings Otolaryngology Head and Neck Surgery 7e (pp. 2311-2327). Philadelphia, PA: Elsevier.

3. Oliver, E.R., Hashisaki, G.T. (2013). Sudden Sensory Hearing Loss. In J.J. Johnson, C.A. Rosen. (Eds.), Bailey’s Head and Neck Surgery-Otolaryngology 5e (pp. 2589-2596). Baltimore, MD: Lippincott Williams & Wilkins.