Olfactory dysfunction following occupational head trauma teruhiro ogawa

Olfactory dysfunction following head trauma has been widely reported, but the risk factors regarding its development have not been fully elucidated. Therefore, 365 head injury patients, who were examined by the senior author (JAR) in Canada between 1993 and 1997, were assessed to determine the incidence of posttraumatic olfactory dysfunction and its association with the severity of head injury and the mechanism of injury in the same cohort group. Olfactory dysfunction was identified in 13.7% (9.3% with anosmia, 4.4% with hyposmia). It occurred more often in cases of loss of consciousness > 1 hr (p = 0.0005), severe head injuries (grade I vs m: p = 0.000001) (grade I vs V ; p<:0.00001) and skull fractures (p = 0.0001). The direction of the blow applied to the skull did not influence its presence although radiologically confirmed skull fractures in the frontal, occipital, skull base and midface were more likely than temporal and parietal fractures to result in an olfactory change (p<0.01). Moreover by multivariate analysis, hypogeusia, nasal bone fracture, occipital bone fracture, skull base fracture, and positive rhinoscopic findings were found to be the most valuable or most closely related factors/conditions in that order among 46 factors that were initially presumed to cause posttraumatic smell disorder.