Relationships between accelerometry and general compensatory movements of the upper limb after stroke

Abstract

Background: Standardized assessments are used in rehabilitation clinics after stroke to measure restoration versus compensatory movements of the upper limb. Accelerometry is an emerging tool that can bridge the gap between in- and out-of-clinic assessments of the upper limb, but is limited in that it currently does not capture the quality of a person's movement, an important concept to assess compensation versus restoration. The purpose of this analysis was to characterize how accelerometer variables may reflect upper limb compensatory movement patterns after stroke.

Methods: This study was a secondary analysis of an existing data set from a Phase II, single-blind, randomized, parallel dose-response trial (NCT0114369). Sources of data utilized were: (1) a compensatory movement score derived from video analysis of the Action Research Arm Test (ARAT), and (2) calculated accelerometer variables quantifying time, magnitude and variability of upper limb movement from the same time point during study participation for both in-clinic and out-of-clinic recording periods.

Results: Participants had chronic upper limb paresis of mild to moderate severity. Compensatory movement scores varied across the sample, with a mean of 73.7 ± 33.6 and range from 11.5 to 188. Moderate correlations were observed between the compensatory movement score and each accelerometer variable. Accelerometer variables measured out-of-clinic had stronger relationships with compensatory movements, compared with accelerometer variables in-clinic. Variables quantifying time, magnitude, and variability of upper limb movement out-of-clinic had relationships to the compensatory movement score.

Conclusions: Accelerometry is a tool that, while measuring movement quantity, can also reflect the use of general compensatory movement patterns of the upper limb in persons with chronic stroke. Individuals who move their limbs more in daily life with respect to time and variability tend to move with less movement compensations and more typical movement patterns. Likewise, individuals who move their paretic limbs less and their non-paretic limb more in daily life tend to move with more movement compensations at all joints in the paretic limb and less typical movement patterns.

Keywords: Accelerometry; Cerebrovascular disease; Stroke rehabilitation; Upper extremity.

Fig. 1

Relationships (x-axis) of compensatory movement scores to accelerometer variables (y-axis). Open symbols are in-clinic calculations, and closed symbols are out-of-clinic calculations. Error bars are 95% confidence intervals for each correlation coefficient. Lack of statistical significance occurs when error bars cross the vertical dashed line at 0

Fig. 2

Relationship of variability of bilateral movement during in-clinic time (a, rho = − 0.32, p < 0.001) and out-of-clinic (b, rho = − 0.35, p < 0.01). This accelerometer variable had a similar moderate relationship both in and out-of-clinic

Fig. 3

Relationship of isolated use of the nonpartetic limb to compensatory movement score, both in-clinic (a, rho = 0.14, p = 0.23) and out-of-clinic (b, rho = 0.61, p < 0.0001). Relationship of the use ratio to the compensatory movement score in-clinic (c, rho = − 0.15, p = 0.18) and out-of-clinic (d, rho = − 0.57, p = 0.18) These variables both had a little to no relationships in-clinic, yet good relationships out-of-clinic

Fig. 4

Relationship of two newly proposed metrics that quantify quality of upper limb movement. a Relationship of the Jerk Asymmetry Index to compensatory movement scores (rho = − 0.19, p = 0.09). b Relationship of the spectral arc length of the paretic limb to compensatory movement scores (rho = 0.29, p < 0.01). In b, one outlier with a spectral arc length of > − 6 has been omitted from the plot. Both variables are from out-of-clinic time and had a low relationship with the compensatory movement score