title: Retronasal and orthonasal olfactory function in relation to olfactory bulb volume in patients with posttraumatic loss of smell.
abstract: OBJECTIVE
  The aims of this study were to evaluate olfactory function with orthonasal and retronasal testing in patients with posttraumatic olfactory loss and to investigate the relation between residual olfactory function and olfactory bulb (OB) volume.
  
  
  METHODS
  A retrospective study of 25 patients with posttraumatic olfactory loss was performed. Orthonasal olfactory function was assessed with the Sniffin' Sticks test kit; retronasal olfactory function was assessed with intraorally applied odors. Magnetic resonance imaging was used to determine OB volume and cortical damage in the frontal and temporal areas.
  
  
  RESULTS
  The main outcomes of the present study were the demonstration of a correlation between olfactory function and OB volume, which was more pronounced for retronasal than for orthonasal olfactory function; retronasal olfactory function was most affected in the patients with the most extensive cerebral damage and was least compromised in patients without such damage; OB volumes were smaller in patients with parosmia compared with those without; and the presence of parosmia was clearly associated with the presence of cerebral damage.
  
  
  CONCLUSIONS
  The data confirm that OB volume is an indicator of olfactory function but, interestingly, in this study, it is largely determined by retronasal olfactory sensitivity. In addition, these results emphasize the role of higher cortical centers in olfactory function, and especially in parosmia, which may, at least in some cases, be related to lesions in the fronto-orbital and anterior temporal cortices. It would be of interest to investigate OB volume further in relation to the prognosis of the disorder.
authors.affiliation: Department of Otorhinolaryngology, Cliniques Universitaires Saint Luc, Brussels, Belgium. philippe.rombaux@orlo.ucl.ac.be
authors.forename: Philippe
authors.initials: P
authors.lastname: Rombaux
authors.forename: André
authors.initials: A
authors.lastname: Mouraux
authors.forename: Bernard
authors.initials: B
authors.lastname: Bertrand
authors.forename: Georges
authors.initials: G
authors.lastname: Nicolas
authors.forename: Thierry
authors.initials: T
authors.lastname: Duprez
authors.forename: Thomas
authors.initials: T
authors.lastname: Hummel
mesh_terms: D000328:Adult; D000368:Aged; D006259:Craniocerebral Trauma / Q000150:complications*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D000857:Olfaction Disorders / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D009830:Olfactory Bulb / Q000473:pathology* / Q000503:physiopathology; D012189:Retrospective Studies; D012903:Smell / Q000502:physiology*