2.2 | Study design and patients
We retrospectively reviewed the medical records of patients who admitted
to [Blinded for review] University Hospital for SSNHL between August
2013 and December 2018. Inclusion criteria for the study included 1)
unilateral SSNHL with a minimum 30 dB HL in three continuous octaves
that had occurred within a course of 3 days; 2) patients who performed
ASSR test withing 2 days after initial audiogram; 3) patients who
received systemic high dose steroid therapy within one month after
onset; 4) patients who had initial and follow-up audiogram. Exclusion
criteria included 1) a history of previous SSNHL; 2) any recognized
cause of SSNHL such as Meniere’s disease, active viral infection,
vestibular schwannoma, or congenital anomalies; 3) a history of chronic
otitis media or otologic surgery.
Age, sex, side of affected ear, the presence of dizziness, ear fullness,
and dizziness, and comorbid diabetes mellitus (DM) were also collected.
All enrolled patients received systemic steroid therapy and/or
intratympanic dexamethasone (ITD) injection within one month after
onset. Systemic steroid therapy was considered the first-line treatment
and comprised a single morning dose of oral steroid each day for 2 weeks
(48 mg of methylprednisolone for 4 days, followed by a taper of 8 mg
every 2 days). ITD injection was administered as a salvage therapy for
patients who did not exhibit recovery after an initial one week of
systemic steroid treatment. ITD injections were performed 3–5 times
with dexamethasone (4 mg/ml) within 2 weeks of diagnosis. No additional
treatment, including antiviral agents, prostaglandin, vitamins, or
hyperbaric oxygen therapy were used as second line treatments.
Patients were divided into two groups according to the difference of
hearing thresholds between pure-tone audiometry (PTA) and ASSR ([ASSR
threshold – pure-tone threshold] at 0.5, 1, 2, and 4 kHz). Because
the ASSR mostly could not measure the hearing thresholds in profound
hearing loss,15 subjects who had more than 90 dB HL
hearing thresholds were excluded in grouping. If the patients had a ≥ 15
dB HL ASSR predicted thresholds compared to pure-tone threshold ([ASSR
predicted threshold – pure-tone threshold] ≥ 15 dB HL) at least one
frequency, it defined as a worse ASSR (WASSR) group. If the patients had
a < 15dB of ASSR predicted thresholds compared to pure-tone
threshold thresholds ([ASSR predicted threshold – pure-tone
threshold] < 15 dB HL) at all frequencies, it defined as a
similar or better ASSR (SBASSR) group.