Our objective was to evaluate longitudinal changes in Microsoft Kinect measured upper extremity reachable workspace relative surface area (RSA) versus the revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R), ALSFRS-R upper extremity sub-scale and Forced Vital Capacity (FVC) in a cohort of patients diagnosed with amyotrophic lateral sclerosis (ALS). Ten patients diagnosed with ALS (ages 52-76 years, ALSFRS-R: 8-41 at entry) were tested using single 3D depth sensor, Microsoft Kinect, to measure reachable workspace RSA across five visits spanning one year. Changes in RSA, ALSFRS-R, ALSFRS-R upper extremity sub-scale, and FVC were assessed using a linear mixed model. Results showed that upper lateral quadrant RSA declined significantly in one year by approximately 19% (p <0.01) while all other quadrants and total RSA did not change significantly in this time-period. Simultaneously, ALSFRS-R upper extremity sub-scale worsened significantly by 25% (p <0.01). In conclusion, upper extremity reachable workspace RSA as a novel ALS outcome measure is capable of objectively quantifying declines in upper extremity ability over time in patients with ALS with more granularity than other common outcome measures. RSA may serve as a clinical endpoint for the evaluation of upper extremity targeted therapeutics.
Keywords: ALS; Kinect; Reachable workspace; longitudinal; motor activity; outcome measure; upper extremity.