Proprioceptive Thresholds Are Indicators of Upper Limb Perception After Stroke

Background Proprioception is critical for daily activities and is often impaired after stroke. Recent studies have highlighted the prevalence of proprioceptive impairments of the upper limb in stroke; however, few studies have examined the relationship between proprioceptive impairments and motor function. Objective We examined how proprioceptive detection thresholds (movement discrimination thresholds [MDTs]) relate to existing assessments of upper limb proprioceptive, motor, and clinical function after stroke. Methods Stroke (N = 39) and control participants (N = 39) completed 5 tasks using the Kinarm Exoskeleton Lab: (1) MDT—a single-arm proprioceptive task assessing movement detection threshold, (2) Position Matching—a bilateral matching task assessing static limb position sense, (3) Kinesthetic Matching—a bilateral matching task assessing sense of limb motion, (4) Visually Guided Reaching—a task assessing upper limb motor control, and (5) Reaching without Vision—a task assessing upper limb motor control with increased reliance on proprioceptive feedback. Results Stroke participants were significantly impaired on all robotic tasks compared to controls. We found that MDT was correlated with bilateral matching robotic tasks of proprioception, including Position Matching (ρ = .64, P < .001) and Kinesthetic Matching (ρ = .56, P < .001). However, MDT was not significantly correlated with robotic tasks of motor control or clinical measures. Conclusions MDT, a single-arm measure that reduces motor requirements in proprioceptive testing, was significantly correlated to existing robotic measures of proprioception. MDT is capable of measuring impairments in perception that may be independent from impairments in action-based motor function.