Objective: To contribute to the better understanding of the pathophysiology of cervical dystonia (CD) we systematically assessed olfactory and gustatory functioning in CD subjects and healthy controls.

Background: The pathophysiology of CD is not completely understood. Current concepts on dystonia pathophysiology propose that basal ganglia, cerebellum and sensorimotor cortex are involved. Animal studies, functional imaging and clinical studies in human subjects suggest that these structures are also concerned with the chemical senses. This overlap let us hypothesize a link between CD and altered smell and taste. In fact, diminished olfactory functioning was found in CD [1-3]. The number of CD subjects assessed was small or the results were compared to normative data. Neuropsychological and psychiatric alterations in CD, which could potentially impede the chemical senses, were not assessed. To the best of our knowledge, taste has not been assessed in CD.

Method: We examined 40 CD subjects (age 61.8±10.9 years, 58% female) and 40 healthy controls (age 61.6±12.2 years, 58% female) in the unmedicated state. Sniffin Sticks were used to evaluate odor threshold, discrimination and identification, whereas Taste Strips were applied for the assessment of the combined taste score. Findings were compared by unpaired t-test. Clinical scores were used to assess motor and non-motor deficits including neuropsychological and psychiatric alterations.

Results: CD subjects had lower scores than healthy controls for odor threshold (5.8±2.4 versus 8.0±3.2; p=0.001) and odor identification (11.7±2.3 versus 13.1±1.3; p=0.001), while there was no difference for odor discrimination (12.0±2.5 versus 12.9±1.8; p=0.097). The combined taste score was lower in CD subjects than in healthy controls (9.5±2.2 versus 11.7±2.7; p<0.001). Regression analyses revealed that age was the main predictor for the olfactory and gustatory decline in CD subjects but not neuropsychological and psychiatric alterations.

Conclusion: CD is associated with olfactory and gustatory deficits. Findings support the idea that basal ganglia, cerebellum and sensorimotor cortex are involved in the pathophysiology of CD.

References: [1] Silveira-Moriyama et al. Olfaction in patients with suspected parkinsonism and scans without evidence of dopaminergic deficit (SWEDDs). J Neurol Neurosurg Psychiatry. 2009 Jul;80(7):744-8. [2] Vemula et al. Role of Gα(olf) in familial and sporadic adult-onset primary dystonia. Hum Mol Genet. 2013 Jun 15;22(12):2510-9. [3] Marek et al. High prevalence of olfactory dysfunction in cervical dystonia. Parkinsonism Relat Disord. 2018 Aug;53:33-36.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/smell-and-taste-in-cervical-dystonia-a-contribution-to-understand-dystonia-pathophysiology/