Publication:

Changes in the hearing threshold using high frequency audiometry in medical personnel exposed to ionizing radiation

Background Effect on sensorineural hearing loss by low dose ionizing radiation exposure in radiation workers has been rarely evaluated. A case control study was done among the radiation associated workers and normal subjects.

Methods The study was done among medical personnels exposed to low dose of ionizing radiation. Age and sex matched healthy control group of subjects were selected. Groups were evaluated by normal otoscopic evaluation; normal tuning fork test and normal standard pure tone audiogram at frequencies from 250 to 8000 Hz. They underwent impedance audiometry, transient evoked otoacoustic emissions, and high frequency audiometry (from frequencies 10000 to 20000 Hz).

Results No statistically significant difference was found in the results of impedance audiometry, transient evoked otoacoustic emissions and standard pure tone audiogram from 250 to 8000 Hz between cases and controls. In high frequency range, statistically significant difference was obtained only at 12500Hz (p=0.001) and 16000 Hz (p=0.001). Mean thresholds were higher at all frequencies in cases compared to controls, except at 4000 Hz. A statistically significant correlation was found between duration of exposure and thresholds at 500 Hz (p=0.014) and 10000 Hz (p=0.048). Tinnitus, vertigo, ear block, hard of hearing and loss of appetite were seen more in cases, but was not significant.

Conclusions Even though using standard pure tone audiometry or high frequency audiometry there was no statistically significant variation in frequencies between cases and controls except at 12500 and 16000 Hz, the mean thresholds were more at almost all frequencies in cases than in controls. Hence a pre placement and periodic high frequency audiometric evaluation in medical personnels with radiation exposure is indicated in future.