MRI Study: Objective Olfactory Function and CNS Pathologies in Patients with Multiple Sclerosis

Abstract

Background: Multiple sclerosis (MS) is a chronic disease characterized by CNS lesions causing physical and cognitive impairment. Using psychophysical testing, an olfactory disorder is diagnosed in 15-38.5% of patients with MS. Olfactometry permits objective testing of the sensory nerve function. Methods: The study looked at 20 patients with MS. Clinical, olfactory (chemosensory evoked potentials), and MRI data (volume of the bulbus olfactorius (BO), olfactory brain (OB), lesions in the CNS) were analyzed. Results: 25 percent of patients were hyposmic, exhibiting higher OB lesion volumes and smaller bulb volumes. H₂S and CO₂ latencies and the BO volume (inversely) correlated with the volume and number of MS lesions of the olfactory brain in all patients. Patients with a smaller olfactory bulb volume exhibited longer H₂S latencies (p = 0.025). Conclusion: A relationship between olfactory bulb volume, olfactory brain lesion load, and objective olfactory function testing in MS patients was investigated in all patients. Our data shows that brain damage characteristic of MS, including reduced bulb volume, causes an increase in chemosensory potential latencies and an olfactory function deficit.