Data from: Tactile and proprioceptive dysfunction differentiates cervical dystonia with and without tremor
Avanzino, Laura et al. (2020), Data from: Tactile and proprioceptive dysfunction differentiates cervical dystonia with and without tremor, Dryad, Dataset, https://doi.org/10.5061/dryad.2264mf4
Objective: To determine if different phenotypes of cervical dystonia (CD) express different types and levels of somatosensory impairment. Methods: We assessed somatosensory function in CD patients with and without tremor (N=12 each) and in healthy age-matched controls (N=22) by measuring tactile temporal discrimination thresholds of the non-dystonic forearm, and proprioceptive acuity in both the dystonic (head/neck) and non-dystonic body segments (forearm/hand) using a joint position-matching task. The head or the wrist was passively displaced along different axes to distinct joint positions by the experimenter or through a robotic exoskeleton. Participants actively reproduced the experienced joint position and the absolute joint position matching error between target and the reproduced positions served as a marker of proprioceptive acuity. Results: Tactile temporal discrimination thresholds were significantly elevated in both CD subgroups when compared to controls. Proprioceptive acuity of both the dystonic and non-dystonic body segments was elevated in patients with CD and tremor with respect to both healthy controls and patients with CD without tremor. That is, tactile abnormalities were a shared dysfunction of both CD phenotypes, while proprioceptive dysfunction was observed in CD patients with tremor. Conclusions: Our findings suggest that the pathophysiology in CD can be characterized by two abnormal neural processes: First, a dysfunctional somatosensory gating mechanism involving the basal ganglia that triggers involuntary muscle spasms. Second, abnormal processing of proprioceptive information within a defective cortico-cerebellar loop, likely affecting the feedback and feedforward control of head positioning. This dysfunction is mainly expressed in CD with tremor.