Gray matter alterations in parosmia

• Published in: Neuroscience Vol. 177; pp. 177 - 182
• Main Authors: Bitter, T, Siegert, F, Gudziol, H, Burmeister, H.P, Mentzel, H.-J, Hummel, T, Gaser, C, Guntinas-Lichius, O
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 17-03-2011; Elsevier
• Subjects: Adult; Aged; Atrophy; Biological and medical sciences; Female; Fundamental and applied biological sciences. Psychology; human; Humans; insula; magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Middle Aged; Nerve Degeneration - pathology; Neurology; olfaction; Olfaction Disorders - pathology; Olfactory Pathways - pathology; Olfactory system and olfaction. Gustatory system and gustation; parosmia; Vertebrates: nervous system and sense organs; volumetry; VBM; magnetic resonance imaging; olfactory bulb; TDI score; volumetry; GM; volume of interest; olfaction; voxel-based morphometry; insula; OFC; VOI; white matter; OB; WM; gray matter; orbitofrontal cortex; parosmia; IC; threshold discrimination identification score; insular cortex; human; Human; Olfaction; Nuclear magnetic resonance imaging
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2011.01.016

Abstract Parosmia is a common olfactory disorder. In this condition, odors are perceived in a different quality than usual. This distorted olfactory percept is typically reported to be unpleasant. Little is known about the pathophysiology of this phenomenon. Previous studies demonstrated smaller volumes of the olfactory bulbs in patients with parosmia compared to subjects without parosmia. In order to investigate structural brain alterations in areas beyond the olfactory bulb, in the current study voxel-based morphometry was applied. A group of 22 parosmic patients was compared with control subjects matched for age- and sex, who exhibited a similar performance in olfactory tests. Performing a whole brain analysis, we found profound gray matter volume loss in the left anterior insula in parosmic patients. In an additional volume of interest analysis including primary and secondary olfactory areas, we also found volume loss in the right anterior insula, the anterior cingulate cortex, the hippocampus bilaterally, and the left medial orbitofrontal cortex. Many of these areas are critically involved in olfactory quality discrimination and odor memory. The present results indicate that reduced gray matter volume in brain regions supporting odor discrimination and memory is related to disturbed olfactory sensation in parosmia.