Cervical Dystonia with Classic Sensory Tricks and Forcible Sensory Trick Showed Different Functional Connectivity Alterations: A Functional Near-Infrared Spectroscopy Study

Background/Objectives: Brain dysfunction and symptoms can be improved with a sensory trick (ST) in more than 80% of patients with cervical dystonia (CD). This study aimed to investigate the functional connectivity (FC) of CD patients with different types of STs using functional near-infrared spectroscopy (fNIRS) and to explore the underlying neural mechanisms of STs. Methods: In this study, 35 CD patients (including 15 with classic STs, 15 with forcible STs, 5 with non-STs) and 29 healthy controls (HCs) underwent resting-state fNIRS. We subsequently analyzed FC differences between the groups and their correlations with clinical characteristics. Results: The grand-average FC was significantly higher in the non-ST group than in the forcible ST group. Furthermore, compared to the ST group, the non-ST group exhibited significantly increased FC, primarily involving the prefrontal and sensorimotor networks. In the forcible ST group, this hypoconnectivity was negatively correlated with disease severity scores. Conclusions: This study supports the concept of CD as a networkopathy, suggesting that both the severity and topology of cortical coherence impairment are modulated by the ST phenotype.