Visual sensory processing is altered in myoclonus dystonia.

Abstract

Abnormal sensory processing, including temporal discrimination threshold, has been described in various dystonic syndromes. To investigate visual sensory processing in DYT-SGCE and identify its structural correlates. DYT-SGCE patients without DBS (DYT-SGCE-non-DBS) and with DBS (DYT-SGCE-DBS) were compared to healthy volunteers in three tasks: a temporal discrimination threshold, a movement orientation discrimination, and movement speed discrimination. Response times attributed to accumulation of sensory visual information were computationally modelized, with μ parameter indicating sensory mean growth rate. We also identified the structural correlates of behavioral performance for temporal discrimination threshold. Twenty-four DYT-SGCE-non-DBS, 13 DYT-SGCE-DBS, and 25 healthy volunteers were included in the study. In DYT-SGCE-DBS, the discrimination threshold was higher in the temporal discrimination threshold (P = 0.024), with no difference among the groups in other tasks. The sensory mean growth rate (μ) was lower in DYT-SGCE in all three tasks (P < 0.01), reflecting a slower rate of sensory accumulation for the visual information in these patients independent of DBS. Structural imaging analysis showed a thicker left primary visual cortex (P = 0.001) in DYT-SGCE-non-DBS compared to healthy volunteers, which also correlated with lower μ in temporal discrimination threshold (P = 0.029). In DYT-SGCE-non-DBS, myoclonus severity also correlated with a lower μ in the temporal discrimination threshold task (P = 0.048) and with thicker V1 on the left (P = 0.022). In DYT-SGCE, we showed an alteration of the visual sensory processing in the temporal discrimination threshold that correlated with myoclonus severity and structural changes in the primary visual cortex. © 2019 International Parkinson and Movement Disorder Society.