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

Abstract

<p class="abstract"><strong>Background:</strong> 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.</p><p class="abstract"><strong>Methods:</strong> The study was designed in low dose of radiation exposing healthy medical personnel. 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) was done. </p><p class="abstract"><strong>Results:</strong> 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 the high frequency range, statistically significant difference was observed (p=0.0001). 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.</p><p class="abstract"><strong>Conclusions:</strong> Taking account of the very low incidence of nerve and parathyroid injury in this series, the authors suggest that meticulous capsular dissection is superior to dissection of the entire nerve in avoiding transcient nerve damage as well as temporary hypocalcemia. However it is stated that a deliberate search for the nerve is definitely indicated in cases where there is likely to be distorted anatomy, as in infiltrating malignancies and recurrent thyroidectomies.</p>