title: Hearing loss following intratympanic instillation of gentamicin for the treatment of unilateral Meniere's disease.
abstract: OBJECTIVE
  To determine the incidence, extent, and time course of hearing loss following instillation of intratympanic gentamicin using a predetermined fixed protocol for incapacitating unilateral Meniere's disease and to determine whether such loss is associated with any identifiable risk factors.
  
  
  METHODS
  A retrospective analysis of all patients treated with intratympanic gentamicin between 1988 and 1998 using American Academy of Otolaryngology-Head and Neck Surgery reporting guidelines (1985 and 1995). A predetermined regimen using a fixed dose (gentamicin 26.7 mg/mL administered three times daily for 4 consecutive days) was used.
  
  
  METHODS
  The records of patients treated with this particular protocol were reviewed. The relationship between pretreatment hearing acuity, pretreatment bithermal caloric response, duration of symptoms, and previous treatment to post-treatment hearing were analyzed with respect to hearing.
  
  
  RESULTS
  Complete vestibular and audiologic data over a minimum 2-year follow-up were available for 85 individuals. Sixty-three patients (74.1%) had unchanged or improved hearing, and 22 patients (25.9%) realized hearing loss. In 80% of the latter, it occurred during the first month post-treatment. When hearing acuity at the 1-month post-treatment interval remained unchanged (91.1%), it was likely to remain so over the next 23 months. A significantly higher incidence of profound hearing loss was noted in patients who developed hearing loss in the first month, as compared with those who developed hearing loss at a later period (p = .0207, relative risk = 1.5). Re-treatment was not associated with hearing loss. The only identifiable risk factor for developing hearing loss was pretreatment hearing acuity stages 3 and 4 (pure-tone average > 40 dB) (p = .022, relative risk = 1.5).
  
  
  CONCLUSIONS
  Hearing loss is a recognized complication of treatment with intratympanic gentamicin, occurring in approximately 26% of individuals. In those individuals in whom hearing acuity has remained unchanged after the first month interval, significant worsening of hearing is unlikely, and patients can be reassured accordingly.
authors.affiliation: Department of Otolaryngology, Sunnybrook and Women's College Health Science Centre and the University of Toronto, Ontario.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Kaplan
authors.forename: Julian M
authors.initials: JM
authors.lastname: Nedzelski
authors.forename: Aziz
authors.initials: A
authors.lastname: Al-Abidi
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Chen
authors.forename: David B
authors.initials: DB
authors.lastname: Shipp
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000009:adverse effects*; D004432:Ear, Middle; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage* / Q000009:adverse effects*; D034381:Hearing Loss / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D015994:Incidence; D007322:Instillation, Drug; D008297:Male; D008575:Meniere Disease / Q000188:drug therapy*; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins