title: Hidden unilateral agenesis of the frontal sinus: human cadaver study of a potential surgical pitfall.
abstract: OBJECTIVE
  The aim of the study was to attract attention to the surgical significance of unilateral agenesis of the frontal sinus hidden by the overlapping expansion of the contralateral sinus toward the agenetic side.
  
  
  METHODS
  Retrospective review of endoscopic transnasal sinus dissections of 55 human cadavers (42, formalin fixated; 13, fresh frozen) was done in a tertiary care academic medical center. Surgical and radiologic findings were noted.
  
  
  RESULTS
  Absence of right frontal sinus ostium in the presence of a connection between the right and left frontal sinuses was demonstrated in 2 (3.6%) cadavers. An absent and an incomplete septum between the frontal sinuses were also noted in these cadavers. No accompanying abnormality of other sinuses was found, and no evidence of previous sinus surgery was noted in these 2 cadavers.
  
  
  CONCLUSIONS
  If one of the frontal sinus ostia cannot be found during sinus surgery, although this sinus and its recess can be seen on the thick-sliced coronal computed tomographic (CT) scans, keep in mind that it may be (3.6%) an agenetic frontal sinus hidden by the extensive pneumatization of the contralateral sinus that is crossing the midline. It may not be possible to foresee this variant preoperatively by endoscopic examinations or thick-sliced CT scans. If there is suspicion, thin-sliced CT scans with reconstruction will be ideal to confirm the agenesis of the frontal sinus and to avoid complications. In the presence of such variant of frontal sinus, 1-sided successful frontal sinusotomy is adequate because this sinus or cell will already be drained through the treated frontal recess.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Ankara University School of Medicine, Ankara, Turkey. ozgursoy.ozan@mayo.edu
authors.forename: Ozan Bagis
authors.initials: OB
authors.lastname: Ozgursoy
authors.forename: Ayhan
authors.initials: A
authors.lastname: Comert
authors.forename: Irfan
authors.initials: I
authors.lastname: Yorulmaz
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Tekdemir
authors.forename: Alaittin
authors.initials: A
authors.lastname: Elhan
authors.forename: Babur
authors.initials: B
authors.lastname: Kucuk
mesh_terms: D002102:Cadaver; D004210:Dissection / Q000379:methods*; D004724:Endoscopy / Q000379:methods*; D005626:Frontal Sinus / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D010254:Paranasal Sinus Diseases / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D015203:Reproducibility of Results