A STUDY OF DRILL INDUCED HEARING LOSS IN THE CONTRALATERAL EAR FOLLOWING MASTOID SURGERY.

Background: Mastoidectomy is the mainstay of COM treatment . Usage of the micro motor drill has an effect on the contralateral ear due to the noise induced by the drill and the sound-conducting characteristic of the intact skull. Aims And Objectives: 1. To identify the drill induced hearing loss in the contralateral ear, by transient evoked otoacoustic emissions following mastoidectomy. 2. To identify the relation between the type of burr tip used and the amount of hearing loss. Methodology: This study consisted of 63 patients that underwent mastoidectomy. A pre-operative PTA and TEOAE was done. PTA was repeated on POD-1 and POD-7. TEOAE was done on POD-1,3 and 7. Intraoperatively, the type of burr tip used and the individual drilling time for each type of drill bit was recorded. Results: 37 patients developed transient SNHL by POD-3. All patients recovered by POD-30. Higher frequencies of 3000 Hz and 4000 Hz were commonly affected. No change was detected on PTA. Conclusion: The drill is not only a source of noise but is also a strong vibration generator. These strong oscillations are transmitted into the cochlea. Thus surgeons should select appropriate burrs and drills to minimize the temporal bone vibrations.

Findings on the Central Auditory Functions of Endemic Disease Control Agents

This study aimed to assess the central auditory functions of endemic disease control agents. This cross-sectional cohort study comprised two groups: the exposed group, with 38 male endemic disease control agents with simultaneous occupational noise and pesticide exposure; and the control group, with 18 age- and sex-matched workers without occupational noise and/or pesticide exposure. All participants underwent pure-tone audiometry, brainstem auditory evoked potentials, dichotic digits test, and transient-evoked otoacoustic emissions suppression effect. There was a significant inter-group difference in waves III and V absolute latencies, and interpeak I–III and I–V latencies bilaterally, with worse results found in the exposed group. Abnormal dichotic digits test results occurred more often in the exposed group, with a significant association between pesticide- and noise-exposure and the abnormal results (p = 0.0099). The transient-evoked otoacoustic emissions with suppression effect did not yield significant inter-group differences. It was concluded that pesticide and noise exposure induce harmful effects on the central auditory functions, particularly on the brainstem and figure-ground speech-sound auditory skills.

Use of transient evoked otoacoustic emissions as a hearing screen after high-intensity noise exposure

Hearing organ damage caused by high-intensity noise continues to be one of the actual problems of modern otorhinolaryngology. This study aims to evaluate the effectiveness of transient evoked otoacoustic emissions (TEOAEs) as a screening method for hearing research. 15 patients (men aged 18 to 28 years) were examined before and after exposure to high-intensity noise of artillery weapons. All patients passed a set of diagnostic tests: otoscopy, whispered voice test, tonal threshold audiometry, and TEOAE. Hearing thresholds according to audiometry did not exceed normal values. However, the number of people who passed the test TEOAE after noise exposure was 46.6% in the right ear and 40.0% in the left ear, which was statistically significantly different from the data obtained before the shooting. The authors conclude that TEOAE allows evaluation of the functional state of the hearing organ better than tonal threshold audiometry. This technique can be used for mass screening of individuals who are most sensitive to the effects of high-intensity noise, as well as for their further in-depth audiological monitoring.

Hearing screening in schoolchildren: accuracy of different criteria used to analyze transient evoked otoacoustic emissions

ABSTRACT Purpose: to compare the accuracy of different criteria used to analyze transient evoked otoacoustic emissions in schoolchildren. Methods: an accuracy study, where an audiological assessment (audiometry, logoaudiometry, tympanometry) and transient emissions were performed with 70 schoolchildren, from the first to the fifth grade of a municipal school, in Northeastern Brazil (6-14 years, 9.9 ± 2 years), with four criteria, all with signal-to-noise ratio ≥ 3 dB, being: criterion A, in all frequency bands; B, in three consecutive frequency bands; C, in three of the five non-consecutive frequency bands; D, in 2, 3 and 4 kHz. Sensitivity, specificity, accuracy and predictive values with their respective confidence intervals of 95% were analyzed. Results: criterion A showed higher sensitivity (92.31%, 95% CI: 67-98%) and lower specificity (17.35%, 95% CI: 10-29%); criterion C higher specificity (84.21%, 95% CI: 72-91%) and higher positive predictive value (52.63%; 95% CI: 51.63-54.63). Accuracy was 82.85% (95% CI 78.23-87.47) in criterion C and 70% (95% CI: 65.38-74.62) in criterion B. Conclusion: criterion C, signal-to-noise ratio ≥ 3dB in three non-consecutive frequency bands, showed the best accuracy, being considered the best choice as a criterion for the isolated use of transient emissions as a hearing screening procedure, in schoolchildren.