Sudden Sensorineural Hearing Loss

Don’t miss this diagnosis in a patient who presents with unilateral hearing loss occurring within 72 hours and has a normal ear examination. These patients frequently get misdiagnosed as having fluid in the middle-ear or having an infection. It is important to recognize this diagnosis, initiate treatment early, and refer to a specialist so that permanent hearing loss can be minimized.   

Sudden sensorineural hearing loss has been reported in up to 5-20 cases per 100,000 per year. Only in roughly 10-15% of these cases is a cause able to be determined. It arises proportionately in men and women, and most commonly in the fourth and fifth decades of life. The hearing loss usually occurs only in one ear, but can occur in both ears as well. Associated symptoms include tinnitus, vertigo, and aural (ear) fullness.

Causes of sudden sensorineural hearing loss are thought to be viral (including cytomegalovirus [CMV], enterovirus, Epstein-Barr [EBV], herpes simplex I and II [HSV-1 and -2], HIV, influenza, mumps, rubella, and varicella zoster [VZV] viruses), bacterial (including Lyme disease, meningitis, and syphilis), fungal (from meningitis), thromboembolic (including stroke), autoimmune (including systemic lupus erythematosus [SLE], multiple sclerosis [MS], Sjogren’s syndrome [SS], and Behcet’s disease), neoplastic (including acoustic neuroma [schwannoma], meningioma, and paraneoplastic), traumatic (including diving, flying, and motor vehicle accidents), surgical (including stapedectomy, lumbar puncture, and general anesthesia), drug induced (including aminoglycosides, and chemo drugs), psychiatric, and from Meniere’s disease.

When a patient presents with the above symptoms, it is imperative to determine if they have true sensorineural hearing loss. It is vital to look into the patient’s ear to rule out fluid in the middle-ear, acute otitis media or externa, cerumen impaction, perforated tympanic membrane (including from cotton swab use), and mass. It is also important to evaluate for temporomandibular joint (TMJ) dysfunction because this can cause the feeling of fullness. A neurologic exam assessing the cranial nerves, gait, and cerebellum should be performed.

Essential diagnostic testing to perform is the Weber and Rinne tuning fork tests to evaluate sensorineural vs. conductive hearing loss. The patient should receive an audiogram performed by an audiologist to document the hearing loss and an MRI with contrast to rule out neoplasm.

Treatment consists of steroids (60 mg prednisone taper over 10-14 days) started as quickly as possible. Steroids given intratympanically can also be used alone or in combination with the oral, if oral therapy fails to recover hearing, or if there is a contraindication to giving systemic steroids. Antiviral treatment can be initiated empirically but has not been proven to show improvement in hearing recovery. Prompt referral to an ENT specialist is required for optimal evaluation.

The prognosis for this condition is good, as most patients’ hearing returns completely within two weeks. The degree of initial hearing loss corresponds to the final degree of recovery, as patients who have minimal hearing loss usually recover in full, whereas those with severe hearing loss may only regain part of their hearing.

There is still a lot to learn about this condition, as the cause for most presentations are not known and universal treatment protocols have not been established. It is important for physicians and clinicians to have a high index of suspicion for this diagnosis, and to not pass it off as just fluid in the middle-ear. The results of misdiagnosing or putting off treatment could mean permanent hearing loss.  

Sources:

Rauch, Steven D. "Idiopathic Sudden Sensorineural Hearing Loss." New England Journal of Medicine 359.8 (2008): 833-40. NEJM.org. Web. 8 Dec. 2011. <http://www.nejm.org/doi/full/10.1056/NEJMcp0802129>.

Schreiber, Benjamin E., Charlotte Agrup, Dorian O. Haskard, and Linda M. Luxon. "Sudden Sensorineural Hearing Loss." The Lancet 375.9721 (2010): 1203-211. TheLancet.com. Web. 8 Dec. 2011. <http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2809%2962071-7/fulltext>.