The purpose of this case study is to support best practices in treating sudden sensorineural hearing loss (SSNHL), particularly the importance of immediate audiological evaluation and treatment of suspected SSNH to ensure an optimal outcome. SSNHL is most commonly defined as a hearing loss of 30 dB or greater at three consecutive frequencies that occur within 72 hours.1 SSNHL can develop at any age, but it most commonly occurs in patients aged 65 and older.2 In the United States,2 it is estimated to affect 27 in every 100,000 people. Those with this condition often discover their hearing loss upon waking up in the morning, after hearing a loud popping sound, or when using their phones on the affected side. Although most cases of SSNHL are idiopathic, differential diagnoses include viral infections and autoimmune diseases (10-15%4), as well as retrocochlear lesions.3,4 Audiological diagnosis should begin with a review of the patient's history for any potential underlying conditions that could explain the hearing loss. If no underlying conditions or other diagnoses can be established, the diagnosis of an SSNHL is assumed. When previous audiometric results are unavailable for unilateral losses, hearing threshold levels and other test findings on the contralateral ear are used as a reference for pre-existing hearing status in the affected ear.
Given the broad nature of the differential diagnoses and the complex nature of SSNHL, management can be complicated, requiring a multidisciplinary approach (e.g., audiologists, otolaryngologists, primary care physicians, etc.). The prognosis is also largely determined by the time between onset and consultation with an appropriate health care provider. Failure to address symptoms immediately can result in a poor outcome and a permanent hearing impairment. The American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) established clinical practice guidelines designed to increase diagnostic accuracy, minimize unnecessary tests, provide consistent treatment, and improve outcomes. AAO-HNS recently updated the guidelines to recommend magnetic resonance imaging (MRI) or auditory brainstem response testing for patients with SSNHL.5 The updated guidelines also emphasize the importance of the time between symptom onset and the initiation of evaluation and treatment. The guidelines also recommend audiological assessment as soon as possible (defined as within 14 days of the onset of symptoms) and at follow-up appointments within six months of completing treatment. Ideally, treatment should be initiated immediately. Unfortunately, not all patients with SSNHL present to an otolaryngologist's office for timely evaluation and definitive diagnosis. For cases with delayed diagnosis and treatment, patients must be informed that spontaneous recovery is possible in one-third to two-thirds of cases,6 usually within the first two weeks.7 We describe here the interdisciplinary assessment and management of a patient with SSNL, and the outcome at three months post-onset.
The patient is a 58-year-old Hispanic woman who was evaluated for sudden unilateral (right ear) hearing loss accompanied by roaring tinnitus. The patient reportedly noted the hearing loss upon waking in the morning on the day of her clinic visit. She also reported hearing a “wind-like” sound in her right ear the night before the appointment. An audiologic evaluation at the same clinic from three years prior to the first appointment showed that her hearing sensitivity was within normal limits in both ears, with pure tone thresholds ranging from 0 to 10 dB HL from 250 to 8,000 Hertz (Hz). Word recognition scores (WRS) during the previous assessment were 100 percent bilaterally with normal tympanograms and acoustic reflexes present at 500 and 1,000 Hz, bilaterally. The patient was reportedly in generally good health with no history of vertigo, tinnitus, or other hearing-related difficulties.
In the patient's initial assessment at our clinic on the day of symptom onset, otoscopy of both ears was unremarkable. Pure tone audiometry revealed a low-frequency SNHL of 70 dB HL at 500 Hz rising to 20 dB at 8000 Hz in the right ear, whereas hearing in the left ear was within normal limits. The patient's WRS was 100 percent for the left ear and 40 percent for the right ear. Aural immittance testing revealed bilateral normal Type A tympanograms. Ipsilateral acoustic reflexes were elicited at normal levels at 500 and 1,000 Hz, bilaterally. Contralateral reflexes were not tested. Distortion-product otoacoustic emissions (DPOAEs) were present in the left ear and absent across all frequencies in the affected right ear. Due to the asymmetrical nature of the audiogram, referrals for an MRI and a complete blood count test were made. Laboratory blood tests were normal, and the MRI confirmed that there was no retrocochlear lesion.
After counseling about her symptoms and test findings, the patient was immediately instructed to consult with an otolaryngologist for evaluation and treatment. Otolaryngological treatment involved oral prednisone therapy, an oral diuretic, and a salt-restricted diet. Lipoflavonoid and Antivert were used to treat the patient's tinnitus and vertigo, respectively. In addition to the audiological assessment on the day of the onset of symptoms, the patient also underwent assessments on post-onset day 7 day and day 25, plus 58 months post-onset. All audiometric evaluations consisted of otoscopy, aural immittance measurements, pure-tone audiometry, speech audiometry, and otoacoustic emissions. Table 1 shows a timeline of the patient's onset, assessment, and management. Figure 1 shows the change in pure-tone average, WRS measured at 80dB HL and OAE amplitudes at 256 Hz across all sessions.
FOLLOW-UP & OUTCOME
As displayed in the timeline in Table 1, there was no delay in managing this patient. Assessment and medical management were initiated on the day of onset. Interestingly, findings for WRS and OAE measurements improved the most in the shortest amount of time, with the WRS increasing from 40 percent to 92 percent within a week of the initiation of treatment. Return of DPOAEs suggests that OAE measurement may offer a reliable and sensitive option for quickly monitoring cochlear status when clinical resources are limited. On the last audiometric evaluation, which was performed four and a half years after the event, all previous audiometric tests were repeated. Pure-tone audiometry, speech audiometry, aural immittance, and OAE findings were all within normal limits, bilaterally.
This case report illustrates the importance of timely diagnosis and treatment of SSNHL. The patient met the criteria for SSNHL as evidenced by the negative history of hearing loss and risk factors (e.g., noise exposure, ototoxicity), normal bloodwork results, rapid onset of unilateral sensorineural hearing loss, and a significant decrease in word discrimination in the absence of any other potential diagnosis. Radiographic imaging confirmed the absence of a retrocochlear lesion. Without any identifiable etiology, the patient was diagnosed with SSNHL consistent with AAO-HNS guidelines for the classification of idiopathic SSNHL.5 Spontaneous recovery occurs in about 32 to 65 percent of patients with idiopathic SSNHL.8,9 Treatment for SSNHL is controversial largely due to the heterogeneous nature of the diagnosis and can involve corticosteroids.
The patient's hearing recovery was likely due to a combination of factors, including age, severity, and configuration of hearing loss, overall health, and treatment onset. The patient's OAE recovery is clinically important as OAEs have been suggested to be a potential indicator of prognosis for recovery from SSNHL.10,11
The immediate evaluation and subsequent treatment of the patient were facilitated in a multidisciplinary hospital setting with an otolaryngologist on-site as well as facilities for imaging and laboratory blood tests and access to audiological and medical services. Audiologists referring patients with suspected SSNHL are encouraged to schedule an appointment with an otolaryngologist as quickly as possible, as was done with this patient. Patient-reported outcome measures can also be used to document the subjective nature and experience with SSNHL. The case history should also include questions about tinnitus and hearing loss. Also, the evaluation should differentiate any causes of conductive hearing loss. Lastly, audiologic rehabi-litation may be recommended for patients with SSNHL to address quality of life, effects on communication, and counseling needs.5 Amplification and rehabilitation, including emotional support, should be provided for patients who confirm the significant impact of SSNHL on their lives, particularly those who do not experience any recovery in their hearing.
The present case study illustrated the importance of timely diagnosis and management of SSNHL. Audiologists and physicians should collaborate to ensure timely plans for evaluation and treatment consistent with the AAO-HNS guidelines.
Editor's note: We acknowledge the assistance of James Hall, PhD, who provided critical reading and review of this manuscript.