無難聴を疑つた6000Hz-dip型急性難聴

抄録

We usually use 6 frequencies, 250, 500, 1000, 2000, 4000 and 8000 Hz, in conventional pure tone audiometry. When these 6 points do not show hearing loss, our clinical diagnosis is no hearing loss. If the hearing loss is not located in the clinical 6 frequencies, we cannot detect it.
The authors diagnosed 6000 Hz-dip type acute hearing loss in a 43-year-old male with tinnitus. We measured the hearing levels at 6 frequencies and found no hearing loss. The pitch of his tinnitus was 6000 Hz, so we measured the hearing levels at 4 other frequencies (800, 1500, 3000 and 6000 Hz) and detected a 6000 Hz-dip.
Steroid treatment cured both the tinnitus and the 6000 Hz-dip hearing loss.
When hearing loss occurs at a frequency other than the conventional pure tone audiometric frequencies, a mistaken diagnosis of no hearing loss is made. If the patient complains of tinnitus, the clinician should investigate the pitch and measure the hearing level near the frequency of the tinnitus. This is a useful method of discovering narrow diptype acute hearing loss.