THE CASE
A healthy 48-year-old man presented to our otolaryngology clinic with a 2-hour history of hearing loss, tinnitus, and fullness in the left ear. He denied any vertigo, nausea, vomiting, otalgia, or otorrhea. He had noticed signs of a possible upper respiratory infection, including a sore throat and headache, the day before his symptoms started. His medical history was unremarkable. He denied any history of otologic surgery, trauma, or vision problems, and he was not taking any medications.
The patient was afebrile on physical examination with a heart rate of 48 beats/min and blood pressure of 117/68 mm Hg. A Weber test performed using a 512-Hz tuning fork lateralized to the right ear. A Rinne test showed air conduction was louder than bone conduction in the affected left ear—a normal finding. Tympanometry and otoscopic examination showed the bilateral tympanic membranes were normal.
THE DIAGNOSIS
Pure tone audiometry showed severe sensorineural hearing loss in the left ear and a poor speech discrimination score. The Weber test confirmed the hearing loss was sensorineural and not conductive, ruling out a middle ear effusion. Additionally, the normal tympanogram made conductive hearing loss from a middle ear effusion or tympanic membrane perforation unlikely. The positive Rinne test was consistent with a diagnosis of idiopathic sudden sensorineural hearing loss (SSNHL).
DISCUSSION
SSNHL is defined by hearing loss of more than 30 dB in at least 3 consecutive frequencies with acute onset of less than 72 hours.1,2 The most common symptoms include acute hearing loss, tinnitus, and fullness in the affected ear.1 The majority of cases of SSNHL are unilateral. The typical age of onset is in the fourth and fifth decades, occurring with equal distribution in both sexes. The annual incidence of SSNHL is 5 to 20 cases per 100,000 individuals worldwide.1,2
Etiology. Identifiable causes of SSNHL include viral infections, vascular events, cochlear hydrops, head trauma, tumors (eg, vestibular schwannoma), and demyelinating disorders. Bilateral SSNHL can be seen in autoimmune diseases and rarely can be caused by medications, such as aminoglycosides or certain chemotherapy medications. However, 90% of cases of SSNHL are considered idiopathic because the etiology cannot be determined.1
Diagnosis. The initial evaluation should include an otoscopic examination, tuning fork tests, and pure tone audiometry.1-3 Weber and Rinne tests are essential when evaluating patients for unilateral hearing loss and determining the type of loss (ie, sensorineural vs conductive). The Weber test (ideally using a 512-Hz tuning fork) can detect either conductive or sensorineural hearing loss. In a normal Weber test, the patient should hear the vibration of the tuning fork equally in both ears. The tuning fork will be heard in both ears in conductive hearing loss but will only be heard in the unaffected hear if sensorineural hearing loss is present. So, for instance, if a patient has a perforation in the right tympanic membrane causing conductive hearing loss in the right hear, the tuning fork would be heard in both ears. If the patient has sensorineural hearing loss in the right ear, the tuning fork would only be heard in the left ear.
The Rinne test compares the perception of sound waves transmitted by air conduction vs bone conduction and serves as a rapid screen for conductive hearing loss. In a positive Rinne test, the patient should be able to hear the vibrating tuning fork next to the pinna louder than when placed against the mastoid bone (ie, air conduction greater than bone conduction). In a negative Rinne test, bone conduction is greater than air conduction, and a conductive hearing loss is present. In our patient, pure tone audiometry, tympanometry, and speech audiometry results were consistent with SSNHL.
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