PATHOPHYSIOLOGY OF POSTTRAUMATIC OLFACTOR Y DISTURBANCES

Background: Head injury is one of the most common causes of olfactory disturbances. The incidence of posttraumatic anosmia depending from th e severity of the injury lies between 5% and over 80%. Methods: Clinic al assessments were performed in 26 cases with posttraumatic anosmia u sing subjective olfactometric tests. Additionally, morphological studi es were performed in 26 other patients, who died between 36 hours and six weeks after head injuries. Results: Frontal basal injuries as well as minor occipital blows are capable of causing complete olfactory lo ss. About one-third of all patients were not aware of their chemosenso ry deficits, especially when associated neurological deficits occured. Moreover, the studies show that: 1: The vulnerability of the fila olf actoria varies extremely and depends on unknown, highly individual par ameters. 2: Trauma can induce local hemorrhage within the olfactory tr acts and bulbs without any other intracranial lesions. 3: An intracere bral contusion is often misunderstood as the direct substrate of a pos ttraumatic anosmia. However, in a number of cases it is merely the sig n of a strong injuring force, potentially capable of injuring the fila or the olfactory bulbus. Conclusions: The findings indicate that the pathophysiology and biomechanics of posttraumatic anosmia should be th e subject of critical diskussion.