Temporal but not spatial dysmetria relates to disease severity in FA

Manuela Corti, Agostina Casamento Moran, Stefan Delmas, Samantha Bracksieck, Jessica Bowman, Blake Meyer, Samantha Norman, Sub Subramony, and Evangelos A Christou, Journal of Neurophysiology 0 0:0 Doi:10.1152/jn.00165.2019

The aim of this study is to characterize dysmetria and its association to functional capacity. Also, we examine the neural mechanisms of dysmetria by quantifying the EMG burst area, duration, and time-to-peak of the agonist muscle. Methods.27 individuals with FA and 13 healthy controls (HC) performed the modified Functional Ataxia Rating Scale (mFARS), and goal-directed movements with the ankle. Dysmetria was quantified as position and time error during dorsiflexion. Results. FA individuals exhibited greater time but not position error than HC. Moreover, time error correlated with disease severity and was related to increased agonist EMG burst. Discussion. Temporal dysmetria is associated to functional capacity, likely due to altered activation of the agonist muscle.