Objective: To determine the utility of quantitative wearable sensors in Multiple system atrophy (MSA).

Background: Symptoms of MSA include parkinsonism, ataxia, and/or failure of the autonomic nervous system. Wearable sensors to assess gait and activity parameters in MSA have potential to characterize motor impairment in an outpatient setting and to serve as clinical trial outcomes.

Method: Participants enrolled in biomarkers of progression in MSA (bioMUSE) were diagnosed with early MSA (<3 years of motor symptoms) by clinical assessment. All completed a neurologic exam, neuroimaging and biofluid assessments. The motor exam of the Unified MSA Rating Scale (UMSARS II) , Parkinson Plus Scale (PPSm), and Tandem Walk (TW), were completed every 3 months. PAMSys actigraphy pendant sensors were worn continuously for up to 12-months, allowing assessment of gait parameters (step count, bouts of walking, steps per bout, cadence, cadence variability), postures (minutes of sitting, lying, standing, walking, sedentary [sitting + lying]) and postural transitions (sit to stand). Clinical assessments were obtained at baseline (BL) and months 3, 6, 9 and 12.   At each time point, sensor parameters were obtained by averaging data over 14-day epochs.   Pearson correlation coefficients between each clinical variable and each sensor variable were estimated at each time point.  The two-sided p-value from the test of the null hypothesis that the true correlation equals zero was computed.

Results: 12 participants (6 Female, mean age 64.2) with an average motor symptom duration of 2 years were followed for ≥ 6 months (n=9), and 12 months (n=5). Significant (P<0.05) correlations were observed between step count, bouts of walking, minutes walking and sit to stand transitions for UMSARS II, PPSm and TW. Significant correlations were most frequently observed at BL and months 3, 6 and 9. The strongest correlations (r>0.8) were observed at month 6 and 9.  The PPSm had more frequent and stronger correlation with sensor parameters than UMSARS II.

Conclusion: In early MSA, continuous activity monitoring is feasible and demonstrates significant correlation with motor exam. The PPSm appeared to have stronger correlation with sensor variables than UMSARS II. Continuous motor assessments via a wearable pendant may be a suitable endpoint for clinical trials in MSA.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/wearable-sensors-for-quantitative-motor-assessments-in-multiple-system-atrophy/