The Arm Movement Detection (AMD) test: a fast robotic test of proprioceptive acuity in the arm

Abstract

BackgroundWe examined the validity and reliability of a short robotic test of upper limb proprioception, the Arm Movement Detection (AMD) test, which yields a ratio-scaled, objective outcome measure to be used for evaluating the impact of sensory deficits on impairments of motor control, motor adaptation and functional recovery in stroke survivors.MethodsSubjects grasped the handle of a horizontal planar robot, with their arm and the robot hidden from view. The robot applied graded force perturbations, which produced small displacements of the handle. The AMD test required subjects to respond verbally to queries regarding whether or not they detected arm motions. Each participant completed ten, 60s trials; in five of the trials, force perturbations were increased in small increments until the participant detected motion while in the others, perturbations were decreased until the participant could no longer detect motion. The mean and standard deviation of the 10 movement detection thresholds were used to compute a Proprioceptive Acuity Score (PAS). Based on the sensitivity and consistency of the estimated thresholds, the PAS quantifies the likelihood that proprioception is intact. Lower PAS scores correspond to higher proprioceptive acuity. Thirty-nine participants completed the AMD test, consisting of 25 neurologically intact control participants (NIC), seven survivors of stroke with intact proprioception in the more affected limb (HSS+P), and seven survivors of stroke with impaired or absent proprioception in the more affected limb (HSS-P).ResultsSignificant group differences were found, with the NIC and HSS+P groups having lower (i.e., better) PAS scores than the HSS-P group. A subset of the participants completed the AMD test multiple times and the AMD test was found to be reliable across repetitions.ConclusionsThe AMD test required less than 15 min to complete and provided an objective, ratio-scaled measure of proprioceptive acuity in the upper limb. In the future, this test could be utilized to evaluate the contributions of sensory deficits to motor recovery following stroke.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-017-0269-3) contains supplementary material, which is available to authorized users.

Reliability, validity, and clinical feasibility of a rapid and objective assessment of post-stroke deficits in hand proprioception

“…While there exist some position matching assessments which are reported to be more rapid (e.g., [ 14 , 50 ]), the duration of the assessment should be put into relation with the information content of the outcome measures and the reliability of the assessment. Nevertheless, the present assessment is relatively quick to administer, comparable to recently developed perturbation detection assessments taking 10–15 min [ 55 , 56 ] and much faster than other assessments using a 2AFC paradigm requiring around 45 min [ 59 ].…”

“…Studies evaluating other assessment approaches using various matching paradigms for different upper limb joints [ 14 , 31 , 32 , 34 , 35 , 38 , 41 , 50 , 54 , 56 , 60 ] or similar joint position DL estimation methods [ 34 , 59 ] reported coefficients of reliability ranging from fair to excellent for most outcome measures. However, it is difficult to compare results, as other approaches may measure different aspects of proprioception, or because some studies investigated the reliability in NIC subjects instead of in the target population, which may lead to non-representative results, due to different inter- and intra-subject variabilities [ 88 ].…”

“…More quantitative approaches have been proposed, for example using simple apparatuses still requiring manual intervention of the examiner (e.g., using protractor scales [ 31 – 34 ] or objects to discriminate by grasping [ 35 ]). Furthermore, a large number of robotic approaches taking advantage of today’s actuation, control and sensing technology for better stimulus control [ 36 ] and using different assessment paradigms have been developed (e.g., matching and movement reproduction methods [ 14 , 37 – 50 ], detection of passive motion [ 51 – 53 ] or perturbations [ 54 – 56 ], as well as difference threshold assessments [ 57 – 59 ]). An essential step when developing a new assessment is the evaluation of its psychometric and clinimetric properties (e.g., reliability, validity, sensitivity, feasibility, and clinical utility) and its potential confounds.…”

Robotic tests for position sense and movement discrimination in the upper limb reveal that they each are highly reproducible but not correlated in healthy individuals

“…Our task is similar to a recently developed robotic Arm Movement Detection (AMD) task which reduced task time to under 15 min by using graded force perturbations applied to a robotic handle held by participants [45]. In the AMD task the force perturbation is increased or decreased and participants are asked to respond to the question "do you feel the perturbation" and a Proprioception Acuity Score is calculated from the threshold and variability for movement detection from 10 trials.…”

“…An alternate approach is to assess proprioception by quantifying the threshold for sensing limb movement, an aspect of kinesthesia. In this approach, proprioceptive acuity is typically measured as the threshold for detecting a difference between two movements [42,43] or the detection of the onset of passive movement of the limb [44,45]. Advantages to this approach are the fact that it does not rely on the use of the contralateral limb or as much on working memory, both of which could confound results.…”