A few chronic tinnitus patients show normal hearing thresholds in the pure tone audiometry from 125Hz to 8000Hz (≤20dB). We report the characteristics of the course of those patients underwent tinnitus retraining therapy (TRT) compared with other patients suffering from chronic and severe tinnitus.
We identified 13 patients with normal hearing thresholds among 242 patients suffering over 3 months, Tinnitus Handicap Inventory (THI) ≥16/100, and follow up period is over 6 months. We divided into two groups - tinnitus with normal audiometry and with hearing loss - and contrasted these patients with age, gender, tinnitus duration, instruments for TRT, loudness and pitch of the tinnitus, THI and Visual Analogue Scale (VAS) scores.
The pitch-match of the tinnitus was higher and tinnitus duration was shorter in normal audiometry. The age is younger and the tinnitus loudness was smaller in normal hearing group significantly. THI of normal audiogram group showed significant improvement on 18 months treatment, though it once got worse on 12 months. THI of hearing loss group showed significant decreases in first 3 months and decreased slightly until 48 months treatment. The VAS scores of annoyance also showed a large decrease in first 3 months and decreased slightly until 24 months. Both THI after 48 months and VAS scores after 24 months treatment showed almost stable until 72 months in hearing loss group.
Chronic tinnitus with normal audiometry and with hearing loss both showed adaptation with TRT. Normal audiometry group with chronic tinnitus may have damage in high frequency though there were not significant differences between two groups as to tinnitus pitch-match. They also need at least 18 months TRT to become adaptation, while 48 months treatment is enough and first 3 months treatment is very important for hearing loss with chronic tinnitus.