**2.2 Audiological assessment**

394 Hearing Loss

prognostic factors affecting the improvement of ISSHL using feature selection analysis and

We reviewed the medical records of ISSHL patients who visited 'Tinnitus & Hearing loss clinic' in Kyung Hee Oriental Medical Hospital, Seoul, Korea from June 2006 to February 2011. Patients who met the definition of ISSHL, which is defined as an abrupt or rapidly progressing hearing loss of at least 25 dB in 3 contiguous frequencies over a period of no more than 3 days, were eligible to participate in this study. We excluded patients with sensorineural hearing loss caused by trauma, noise, tumors, otitis media or Meniere's

Of a total 117 patients, ten had Meniere's disease, two had senile progressive hearing loss, four had hearing loss in both ears, one had otitis media and twenty-eight failed to undergo a follow up audiogram. Therefore, 72 patients (40 males, 32 females) were enrolled in this study (Fig. 1). This study was approved by the Institutional Review Board of Kyung Hee

Enrollment (n=72)

Improvement (n=36 (50.0%))

disease. Additionally, patients were ineligible if they have hearing loss in both ears.

decision tree model.

**2. Materials and methods 2.1 Patients and eligibility** 

Fig. 1. Flow chart of the study

Oriental Medical Hospital (KOMCIRB-2011-09).

All patients underwent a full physical exam as well as a routine audiological evaluation and otolaryngologic history was also recorded. Magnetic resonance images were acquired if necessary. Pure tone audiograms were conducted using a *GSI 61 audiogram (Grason-Stadler, Inc., WI, USA)* on the day of the initial visit and the day of the follow-up measurement, which was usually after 10 rounds (1st follow-up) and 20 rounds (2nd follow-up) of AT. However, the follow-up measurement was performed before 10 or 20 rounds of acupuncture for some patients who request an earlier audiogram because they felt clear improvement. If partial improvement in the audiogram was observed at the time of the first follow-up measurement, AT was continued until the second follow-up measurement. The hearing results were evaluated based on the pure tone average (PTA) of 4 frequencies (250, 500, 1000, 2000 Hz). A clear improvement of hearing was defined as a final hearing level less than 25 dB and a partial improvement of hearing was defined as a final hearing level not less than 25dB but decreased in PTA of 10 dB or more.
