Effects of a Robot-aided Somatosensory Training on Proprioception and Motor Function in Stroke Survivors

Abstract

Background- Proprioceptive deficits after stroke are associated with poor upper limb function, slower motor recovery, and decreased self-care ability. Improving proprioception should enhance motor control in stroke survivors, but current evidence is inconclusive. Thus, this study examined whether a robot-aided somatosensory-based training requiring increasingly accurate active wrist movements improves proprioceptive acuity and motor performance in chronic stroke. Methods - Twelve adults with chronic stroke completed a 2-day training (age range: 42 – 74 years; median time-after-stroke: 12 months; median Fugl-Meyer UE: 65). Retention was assessed at Day 5. Grasping the handle of a wrist-robotic exoskeleton, participants trained to roll a virtual ball to a target through continuous wrist adduction/abduction movements. During training vision was occluded, but participants received real-time, vibro-tactile feedback on their forearm about ball position and speed. Primary outcome was the just-noticeable-difference (JND) wrist position sense threshold as a measure of proprioceptive acuity. Secondary outcomes were spatial error in an untrained wrist tracing task and somatosensory-evoked potentials (SEP) as a neural correlate of proprioceptive function. Ten neurologically-intact adults were recruited to serve as non-stroke controls for age, gender and hand dominance (age range: 44 to 79 years; 6 women, 4 men).Results – Participants significantly reduced JND thresholds at posttest and retention (F(2, 38) = 4.54, p = 0.017, ηp2 = 0.20) in both groups. A higher pretest JND threshold was associated with a higher threshold reduction at posttest and retention (r = -0.86, -0.90, p ≤ 0.001) among the stroke participants. Error in the untrained tracing task was reduced by 22% at posttest, yielding an effect size of w = 0.13. Stroke participants exhibited significantly reduced P27-N30 peak-to-peak SEP amplitude at pretest (U = 11, p = 0.03) compared to the non-stroke group. SEP measures did not change systematically with training.Conclusion - This study provides proof-of-concept that non-visual, proprioceptive training can induce fast, measurable improvements in proprioceptive function in chronic stroke survivors. There is encouraging but inconclusive evidence that such somatosensory learning transfers to untrained motor tasks.Trial Registration Clinicaltrials.gov; Registration ID: NCT02565407; Date of registration: 01/10/2015; URL: https://clinicaltrials.gov/ct2/show/NCT02565407

Robot-Aided Assessment of Human Ankle Joint Position Sense and Motion Sense

“…Robotic technology has been developed to diagnose proprioceptive dysfunction of the upper limb. For example, recent studies using a wrist/hand exoskeleton robotic system have documented its usefulness in the evaluation of the joint position sense in healthy individuals and stroke survivors [51][52][53][54]. The current study extended such application to the ankle joint, which is a critical joint for balance and locomotion.…”

“…Coupled with an adaptive psychophysical testing paradigm, it is capable ofreliably and comprehensively assessing two major modalities of proprioceptive function -ankle position and motion sense. It yields established psychophysical measures of proprioceptive bias and precision, which are known to be affected in clinical populations with compromised proprioception, such as survivors of stroke [54] or children with developmental coordination disorder [55]. The system is easy to use and does not require extensive training, making it feasible to use as a diagnostic tool in clinical settings.…”

Tactile Sensation Improves Following Motor Rehabilitation for Chronic Stroke: The VIGoROUS Randomized Controlled Trial

“…Consistent with this, in a recent study of people with chronic stroke, participants experienced improved wrist position sense accuracy following just two 24-minute sessions of robotic wrist training. 42…”

“…Consistent with this, in a recent study of people with chronic stroke, participants experienced improved wrist position sense accuracy following just two 24-minute sessions of robotic wrist training. 42 An increase in afferent input may drive improved tactile sense following motor rehabilitation. Regardless of whether motor practice involved object manipulation, study participants experienced increased afferent input from the skin, muscle, and joint receptors during motor practice.…”

Cortical Reorganization of Early Somatosensory Processing in Hemiparetic Stroke

“…VTGs provide vibratory input to the paretic limb of chronic stroke survivors and have been shown to promote neural plasticity and reduce spasticity [45,46]. Other studies have used robot-assisted somatosensory training and vibrotactile biofeedback devices [47,48].…”