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 have potential to characterize motor impairment in an outpatient setting and to serve as clinical trial outcomes in MSA.

Design/Methods:

Participants enrolled in biomarkers of progression in MSA (bioMUSE) had early MSA (<3 years of motor symptoms) by clinical assessment. All completed neurologic exam, neuroimaging and biofluid assessments. The Unified MSA Rating Scale motor exam (UMSARS II), Parkinson Plus Scale (PPSm), and Tandem Walk (TW), were completed every 3 months. PAMSys actigraphy sensors were worn continuously for up to 12-months to assess gait (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) by averaging data over 14-days.   Pearson correlation coefficients between clinical and sensor variables were estimated at each time point and two-sided p-values were calculated.

Results:

12 participants (6 Female, mean age 64.2) with motor symptoms of 2.X 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.

Conclusions:

In early MSA, continuous actigraphy 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 wearable sensors may be a suitable endpoint for clinical trials in MSA.