POSTTRAUMATIC OLFACTORY DYSFUNCTION - MR AND CLINICAL-EVALUATION

PURPOSE: To evaluate the sites of injury in patients with posttraumati c olfactory deficits and to compare damage with findings on clinical o lfactory tests. METHODS: Twenty-five patients with posttraumatic olfac tory dysfunction were examined by means of olfactory testing, endoscop y, and MR imaging. MR surface-coil scans through the olfactory bulbs a nd tracts and head-coil scans of the temporal lobes were evaluated. Qu antitative and qualitative gradings of damage to the olfactory bulbs, tracts, subfrontal region, hippocampus, and temporal lobes were compar ed with results on tests of odor identification, detection, memory, an d discrimination. RESULTS: Twelve patients were anosmic, eight had sev ere impairment, and five were mildly impaired. Injuries to the olfacto ry bulbs and tracts (88% of patients), subfrontal region (60%), and te mporal lobes (32%) were found, but these did not correlate well with i ndividual olfactory test scores. Volumetric analysis showed that patie nts without smell function had greater volume loss in olfactory bulbs and tracts than did those posttraumatic patients who retained some sen se of smell. Qualitative and quantitative assessments of damage showed few significant correlations with olfactory tests, probably because o f multifocal injuries, primary olfactory nerve damage, and the constra ints of a small sample size on the detection of clinically significant differences. CONCLUSION: MR imaging shows abnormalities in patients w ith posttraumatic olfactory dysfunction at a very high rate (88%), pre dominantly in the olfactory bulbs and tracts and the inferior frontal lobes.