Sensorineural Hearing Loss and Brain Stem Auditory Evoked Potential Changes During Interferon Therapy: A Prospective Study in Nine Patients

Abstract

We prospectively studied the sensorineural hearing loss in 12 patients who underwent interferon therapy. Interferon alfa was subcutaneously injected at a dose of 3 or 5 million units daily for 5 days in the first week and then thrice weekly until 6 months. None of our patients received analgesics for fever in the first week, and none received any medications affecting hearing ability. The audiometry and brain-stem auditory evoked potentials (BAEF) were assessed prior to, at 3 months of interferon therapy and at one month after the end of therapy. Three patients were excluded for incomplete follow-up. Three of the remaining 9 patients had a hearing threshold＞30 dB (60 dB at 4 and 8 Hz, 55 dB at 8 Hz, and 55 dB at 4 and 8 Hz) prior to the therapy. Two of them experienced with a 15-dB (from 10 dB to 25 dB at 8 Hz and from 20 dB to 35 dB at 4 Hz) increase of hearing threshold at 3 months of therapy. Their hearing threshold improved after the termination of interferon therapy (from 25 dB to 10 dB and from 35 dB to 30 dB). The I-V interpeak latency (IPL) of BAEF was 4.27±0.15,4.12±0.14, and 4.20±0.14 ms prior to, at 3 months, and at one month after therapy, respectively. None of the patients had abnormal I-VIPL. The change of I-VIPLs (from 4.27 ms to 4.36 ms and from 4.17 ms to 4.56 ms) during interferon therapy was not significant. Our preliminary study showed 22% of patients had mild sensorineural hearing impairment during interferon therapy; this impairment was reversible after the termination of therapy. The brainstem function was preserved during interferon therapy. However, our case number is small, further study with larger case number is necessary.