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F57 Quantitative motor assessment of upper limb ataxia with q-motor: a cross-sectional validation study including novel ataxia tasks – lessons learnt for HD
  1. Pascal Barallon1,
  2. Andreas Traschütz2,3,
  3. Dominik Hermle2,3,
  4. Robin Schubert1,
  5. Rebecca Schüle2,3,
  6. Ralf Reilmann1,2,4,
  7. Matthis Synofzik2,3
  1. 1George Huntington Institute, Münster, Germany
  2. 2Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
  3. 3German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
  4. 4Department of Clinical Radiology, University of Münster, Münster, Germany

Abstract

Background and Objective With its relevance for everyday function, upper-limb-coordination is an insufficiently explored domain for digital-motor-outcomes in ataxia. Leveraging the trial-ready quantitative-motor (Q-Motor) system, we developed and validated a comprehensive task battery to capture upper-limb-ataxia.

Methods Cross-sectional single-center-study (46 patients with predominantly degenerative cross-genotype cerebellar-ataxias (mean-age: 50 years; mean-SARA: 12 points), and 48 age- and sex-matched controls. Q-Motor assessments with a force transducer and an electromagnetic position sensor comprised both existing bilateral-tasks particularly promising for ataxia (foot-tapping, finger-tapping, diadochokinesia, grip-lift) (47 parameters/side), and tasks newly designed to capture ataxia (multi-directional two-dimensional-target-pointing, spiral-drawing) with the dominant hand (450 parameters, including spatial, temporal, spatiotemporal, and texture measures).

Results Target hits per second (AUC: 0.97) and frequency of foot-tapping, finger-tapping or diadochokinesia (AUC: 0.91-0.94) were excellent discriminators between ataxia and controls. Target hits per second and finger-tapping-frequency correlated strongly with the SARA (Spearman rho: -0.87 and -0.81), and even specifically with the sum of its upper limb items (-0.85 and -0.72). For diadochokinesia, temporal variability showed the strongest correlation with SARA (0.71) and its upper-limb composite (0.67, all p<0.001). Parameters in upper-limb tasks had moderate to strong correlations with activities-of-daily-living-function (FARS ADL, |rho|: 0.5-0.6), and dexterity as assessed by the 9-hole peg-test (0.53-0.78, all p<0.001).

Discussion and Conclusion Severity of upper-limb ataxia can be captured by Q-Motor with physiologically interpretable and functionally relevant measures of a finger-tapping, diadochokinesia, and a novel two-dimensional target-pointing-task of interest also for HD. Longitudinal assessments are ongoing to explore their responsiveness to change in a clinical trial setting.

  • Q-Motor
  • quantitative assessment
  • clinical trials
  • ataxia

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