High resolution magnetic resonance (MR) imaging allows for the evaluation of the conductive pathway of olfaction; the olfactory bulbs, the olfactory tracts, and a number of central regions associated with olfactory processing, the amygdaloid-hippocampal complex, and the entire temporal lobe. In patients with congenital anosmia and head injury, the basic for the olfactory site of such deficits is often unclear. MR can detect the morphologic abnormalities which may pinpoint the site of such deficits and lead to a statement of prognostic importance in at least some of these patients. In this component of the Smell and Taste Center's program, we ill evaluate 30 patients with congenital anosmia, 30 patients with decreased olfaction due to head trauma, 30 patients with miscellaneous causes of smell deficits, and 60 age- and sex-matched controls to assess olfactory bulb and tract volume, as well as hippocampal and temporal lobe volume. Olfactory deficits in congenitally anosmic patients can be due to genetically transmitted syndromes associated with bulb and tract aplasia (Kallmann's syndrome), as well as non-hereditary causes, where the defect may not be so clear. Traumatic causes of olfactory dysfunction may be secondary to axonal injury, hematomas or shearing abnormalities of the olfactory bulb, tract, frontal lobe, or temporal lobe. The potential for restoration of olfaction can be best assessed by understanding the morphologic deficit involved. Volumetric analysis of the olfactory bulbs and tracts, hippocampus, and temporal lobe will be performed via three dimensional analysis of MR scans taken at 3 millimeter intervals through the representative anatomy. A surface coil will be used to study the olfactory bulbs and tracts, whereas a head coil will be used for evaluation of the various portions of the temporal lobe. T1 weighted scans with contiguous high resolution thin section imaging will be used with a computer analysis program. By comparing the volumetric analysis of the olfactory bulbs and tracts, hippocampal-amygdaloid complex, and temporal lobes in patients with congenital anosmia, head trauma, and neurodegenerative or obstructive lesions with age and sex-matched controls, we will be able to assess the morphologic site of olfactory deficit and counsel patients on the genetic and/or prognostic implications of their deficit. The MR quantitative studies will be correlated with tests of odor identification, detection, recognition, and memory performed in the Core facility.
Showing the most recent 10 out of 93 publications
