title: Effect of mastoid drilling on hearing of the contralateral ear.
abstract: OBJECTIVE
  This study aimed to: understand the effect that high intensity noise associated with drilling (during otological surgery) has on hearing in the contralateral ear; determine the nature of hearing loss, if any, by establishing whether it is temporary or persistent; and examine the association between hearing loss and various drill parameters.
  
  
  METHODS
  A prospective clinical study was carried out at a tertiary centre. Thirty patients with unilateral cholesteatoma and normal contralateral hearing were included. Patients were evaluated pre-operatively and for five days following surgery using high frequency pure tone audiometry, and low and high frequency transient evoked and distortion product otoacoustic emission testing.
  
  
  RESULTS
  The findings revealed statistically significant changes in distortion product otoacoustic emissions at high frequencies (p = 0.016), and in transient evoked otoacoustic emissions at both low and high frequencies (p = 0.035 and 0.021, respectively). There was a higher statistical association between otoacoustic emission changes and cutting burrs compared with diamond burrs.
  
  
  CONCLUSIONS
  Drilling during mastoid surgery poses a threat to hearing in the contralateral ear due to noise and vibration conducted transcranially.
authors.affiliation: Department of ENT and Head and Neck Surgery, University College of Medical Sciences and Guru Teg Bahadur Hospital, New Delhi, India.
authors.forename: A
authors.initials: A
authors.lastname: Goyal
authors.forename: P P
authors.initials: PP
authors.lastname: Singh
authors.forename: A
authors.initials: A
authors.lastname: Vashishth
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001301:Audiometry, Pure-Tone; D002648:Child; D018424:Cholesteatoma, Middle Ear / Q000601:surgery*; D007758:Ear, Inner; D005260:Female; D006317:Hearing Loss, Noise-Induced / Q000209:etiology* / Q000517:prevention & control; D006801:Humans; D008297:Male; D008416:Mastoid / Q000601:surgery*; D008875:Middle Aged; D010033:Otitis Media / Q000601:surgery; D017084:Otoacoustic Emissions, Spontaneous; D013506:Otologic Surgical Procedures / Q000009:adverse effects* / Q000295:instrumentation; D011183:Postoperative Complications; D011446:Prospective Studies; D013997:Time Factors; D055815:Young Adult