title: Posterior tympanotomy is a riskier procedure in chronic otitis media than in a normal mastoid: a high-resolution computed tomography study.
abstract: OBJECTIVE
  The aim of our study was to compare the difficulty in performing a posterior tympanotomy in chronic otitis media (COM) versus the same procedure in a normal mastoid.
  
  
  METHODS
  The study included 122 patients who underwent tympanomastoidectomy for unilateral chronic otitis media with contralateral normal mastoid pneumatization. We evaluated the anatomical relationships between the mastoid segment and neighboring structures by analyzing axial temporal bone computed tomography scans. A vertical line (line A) was drawn tangential to the most lateral end of the posterior semicircular canal (point A). Three distances were measured: the distance (D1) between the point A and the most lateral end of the mastoid segment of the facial nerve (point B), the distance (D2) between the line A and the point B, and the distance (D3) between the point B and the posterior end of the bony annulus of the external auditory canal.
  
  
  RESULTS
  The average measurements of D1 and D3 were 3.79 ± 0.55 and 2.63 ± 0.51 mm, respectively, in the normal mastoid ears and 3.47 ± 0.59 and 2.35 ± 0.44 mm, respectively, in the COM ears. The measurements of D1 and D3 were statistically shorter in the COM ears than in the normal ears.
  
  
  CONCLUSIONS
  These findings suggest that the facial recess in COM may be narrower than in a normal mastoid and that performing a posterior tympanotomy may be riskier in COM than in a normal mastoid due to the potential for injury to the neighboring structures and the facial nerve.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Hallym University, 445 Gil-Dong, Gangdong-gu, Seoul, 134-701, Korea. kcw5088@dreamwiz.com.
authors.forename: Chang Woo
authors.initials: CW
authors.lastname: Kim
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Hallym University, 445 Gil-Dong, Gangdong-gu, Seoul, 134-701, Korea.
authors.forename: Oh Joon
authors.initials: OJ
authors.lastname: Kwon
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Hallym University, 445 Gil-Dong, Gangdong-gu, Seoul, 134-701, Korea.
authors.forename: Jang Hee
authors.initials: JH
authors.lastname: Park
authors.affiliation: International Health Care Center, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Yeo Hoon
authors.initials: YH
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D002908:Chronic Disease; D004424:Ear Canal / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005154:Facial Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D020220:Facial Nerve Injuries / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control*; D008297:Male; D008416:Mastoid / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D008875:Middle Aged; D008876:Middle Ear Ventilation / Q000009:adverse effects*; D010033:Otitis Media / Q000000981:diagnostic imaging / Q000601:surgery*; D012189:Retrospective Studies; D012306:Risk; D013701:Temporal Bone / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Chorda tympani nerve; Computed tomography; Facial nerve; Otologic surgical procedure