Understanding cognitive features of cervical dystonia: application of the cerebellar cognitive affective syndrome scale (CCAS-S)

Cervical Dystonia (CD) is now recognized to encompass a constellation of non-motor symptoms, including sensory, cognitive, and psychiatric manifestations, which significantly affect patients' quality of life. Cerebellar dysfunction may affect cognitive and affective processing in CD, mirroring cognitive and affective patterns observed in Cerebellar Cognitive and Affective Syndrome (CCAS). To investigate impairments in cerebellar-dependent cognitive and affective domains in CD patients using the Cerebellar Cognitive and Affective Syndrome scale (CCAS-S), and to analyze the potential relationship between cognitive deficits and clinical features of CD. The CCAS-S was administered to twenty CD patients and twenty controls (HC) matched for age, gender, level of education, and MMSE score. For CD patients, disease severity and disability were evaluated using the Toronto Western Spasmodic Torticollis Rating Scales (TWSTRS), while tremor was assessed through the Fahn-Tolosa-Marin Clinical Rating Scale for Tremor (FTM). CD exhibited a significantly lower total CCAS-S score, and a higher number of failed items compared to HC, with marked deficits in specific sub-items such as fluency, delayed verbal recall, similarities, and affective domain. The total number of failed tests revealed high predictive ability (AUC = 0.90), with no significant correlations between disease duration, clinical outcomes, and CCAS-S performance. The CCAS-S is a sensitive screening tool in differentiating cognitive performance in CD and HC, showing a critical cerebellar involvement in the cognitive and affective symptoms of dystonia.