1 | INTRODUCTION
Sudden sensorineural hearing loss (SSNHL) is defined as a sensorineural
hearing loss greater than or equal to 30 dB HL over at least three
consecutive frequencies, occurring within 3 days.1Although the exact etiology is not well clarified, viral infection,
vascular compromise, autoimmune processes, and labyrinthine membrane
ruptures have been proposed as possible etiologies.1,2Given the ambiguity of the etiology of SSNHL, a number of different
regiments have been used as therapy, including vasodilators,
anticoagulants, corticosteroids, vitamins, plasma expanders, antiviral
agents, diuretics, and hyperbaric oxygen.3-5 None of
the treatment options have superiority on the others in randomized
clinical trials,6 but systemic high dose steroid is
currently the most widely accepted treatment for
SSNHL.3-5
The natural history of SSNHL is still obscure. SSNHL may recover
spontaneously in up to 65% of the patients.7,8However, nearly 40% of steroid-treated cases did not recover at all, or
the hearing worsened over the treatment period.9 Thus,
identification of prognostic factors is needed to predict the
spontaneous recovery and risk for permanent or progressive hearing loss
requiring maximal treatment. Many prognostic factors have been reported
for SSNHL. Advanced age, presence of vertigo at onset, more severe
initial hearing loss, descending type of audiogram, cardiovascular risk
factors such as diabetes were shown to be negatively correlated with
recovery.10 In recent years, several authors have
reported on the clinical application of electrophysiologic hearing tests
such as otoacoustic emissions (OAEs) or auditory brainstem response
(ABR) in patients with SSNHL.11-14 However, there has
been no report on the predictive value of auditory steady-state response
(ASSR) in the hearing prognosis of SSNHL. The purpose of the present
study was to investigate whether ASSR can be a prognostic indicator of
hearing outcome in patients with SSNHL.