title: Surgical and anatomic considerations in endoscopic revision of failed external dacryocystorhinostomy.
abstract: OBJECTIVE
  To identify key anatomic considerations in endoscopic revision dacryocystorhinostomy (r-EnDCR) following failed external dacryocystorhinostomy (ExDCR).
  
  
  METHODS
  Case series with chart review.
  
  
  METHODS
  Tertiary care academic medical center.
  
  
  METHODS
  A retrospective review of patients undergoing r-EnDCR after failed ExDCR over the past 6 years was performed. Those with primary or previous EnDCR, proximal nasolacrimal procedures, and nasolacrimal lesions were excluded. All patients had a preoperative maxillofacial computed tomography (CT) scan. Data were collected on patient demographics, clinical characteristics, and radiographic findings. A classification system for the anterior ethmoid-lacrimal fossa complex anatomy was developed.
  
  
  RESULTS
  Twenty-five r-EnDCRs were performed on 22 patients after failed ExDCR. Concurrent sinusitis and previous maxillofacial trauma were seen in 9% (2/22) of patients. CT scan demonstrated anterior ethmoid pneumatization with agger nasi cells in 88% (22/25) of patients, and 95% (21/22) of these partially overlapped the medial aspect of the lacrimal fossa, resulting in a DCR ostium located within the middle meatus. The presence of ipsilateral septal deviation, concha bullosa, and middle turbinate lateralization or scarring to the lateral nasal wall was seen in 24% (6/25).
  
  
  CONCLUSIONS
  In this case series, a large proportion of patients who had failed an ExDCR had an agger nasi cell, suggesting that variability of the anterior ethmoid anatomy may contribute to surgical failure following ExDCR. CT imaging and endoscopy, which are not always performed prior to ExDCR, can help to elucidate the pattern of agger nasi pneumatization as it relates to the lacrimal fossa and to optimize placement of the DCR ostium.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Liang
authors.forename: Kevin
authors.initials: K
authors.lastname: Hur
authors.forename: Shannath L
authors.initials: SL
authors.lastname: Merbs
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Lane
mesh_terms: D003608:Dacryocystorhinostomy / Q000379:methods*; D004724:Endoscopy / Q000379:methods*; D005260:Female; D006801:Humans; D007767:Lacrimal Duct Obstruction / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009301:Nasolacrimal Duct / Q000033:anatomy & histology; D012086:Reoperation; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure
keywords: anatomy; endoscopic dacryocystorhinostomy; ethmoid; lacrimal fossa; revision