Sudden Sensorineural Hearing Loss (SSNHL): Case Report
History
A 28-year-old man visited a hearing clinic with a complaint of experiencing hearing loss from left ear on waking up in the morning. He was hearing well from both his ears when he went to bed last night. His hearing from right was normal at the time of presentation. According to the patient his hearing from left ear had worsened in the interim between waking up in the morning and visit to the hearing clinic in the afternoon. There was no complaint of associated tinnitus or vertigo. There was no other complaint associated with ear, nose, or throat. There was no history of head and neck trauma or any exposure to sudden loud noise.
Examination
The Hearing Instrument Specialist (HIS) on duty performed the otoscopic examination. Both the external auditory canals and ear drums were normal in appearance.
Audiological Evaluation
Tympanograms showed normal middle ear pressure and normal tympanic membrane mobility bilaterally. Acoustic reflexes were absent to ipsilateral stimulation bilaterally.
Pure Tone Audiogram (See above) showed borderline normal to normal thresholds across all frequencies. In the right ear. Left ear showed borderline normal with a drop to moderately-severe sensorineural hearing loss from 500 Hz to 2000 Hz rising to normal at 3000 Hz and above. Audiometric weber demonstrated lateralization to right side.
Speech reception thresholds were within PTA thresholds. Word recognition scores showed excellent speech scores at soft conversational levels in the right ear but these scores very poor in left ear.
Action taken
Keeping in mind the chief complaints of the patient, sudden onset and progression of the symptoms the HIS recommended immediate further otological examination for sudden hearing loss.
Patient did not return for follow-up examination. A telephonic follow-up at the end of three months since onset of symptoms was made. Patient said he had almost fully recovered.
Discussion
According to National Institute on Deafness and other communication disorder (NIDCD) criteria Sudden Sensorineural Hearing Loss (SSNHL) is defined as, “Subjective sensation of hearing impairment in one or both ears developing within 72 hours and a decrease in hearing of more than or equal to 30 decibels (dB), on 3 consecutive frequencies in comparison to normal ear on pure tone audiometry”. Vertigo and/or tinnitus may be the accompanying symptoms.
Identifiable causes of sudden SNHL include autoimmune, infectious, functional, metabolic, neoplastic, neurological, toxic, traumatic, and vascular. The degree of recovery of hearing thresholds is variable and can range between little to full and is not dependent on etiology of sudden SNHL. Some of the factors that determine the extent of recovery of hearing thresholds include age at the time of onset, severity of symptoms and frequencies affected, presence of associated symptoms such as vertigo, and lag between onset of symptom and initiation of treatment. SSNHL is a medical emergency and must be managed on emergent basis.
When a Clinician comes across a patient with sudden SNHL it is always rewarding to document his/her age, time since onset, progression of hearing loss, presence or absence of any co-morbidities, associated symptoms such as tinnitus or vertigo, history of recent use of ototoxic drugs, and improvement of hearing loss if any.
SSNHL is considered a medical emergency. The patient must get urgent attention from a medical professional. As a HIS you must be aware of your role and responsibilities if you are attending to a patient with SSNHL. You must refer the patient to medical professional immediately as any delay in instituting treatment may result in permanent hearing loss.
HIS, audiologists, medical professionals commonly come across the patients who present with history sudden hearing loss. In majority of patients no specific cause may be attributed. An effort should be made to find out possible cause for the condition. The final outcome depends upon a number of factors such as age of the patients, severity of the hearing loss, and presence or absence of accompanying symptoms such as tinnitus or vertigo. Any delay in instituting treatment may also impact the outcome. The idiopathic SSNHL may get better without any treatment in a set of patients. However medical professionals mainly use corticosteroids for treatment of idiopathic SSNHL. (Kuhn M, 2011)
Bibliography
Kuhn M, H.-A. S. (2011). Sudden sensorineural hearing loss: a review of diagnosis, treatment, and prognosis. Trends Amplif., 91-105.