An Objective Technology-based Assessment of Arm and Hand Sensorimotor Disability in Neurological Disorders

Abstract

Background. Detailed assessments of upper limb disability are essential to understand and monitor sensorimotor recovery. Usually, multiple timeconsuming assessments are required to define a holistic sensorimotor profile of proximal (shoulder-elbow) and distal (wrist-hand) impairments and their impact on the capacity to perform activities. We propose and evaluate a novel physiologically-motivated computational framework for objectively assessing sensorimotor profiles in neurological patients using a single, rapid technologybased assessment involving goal-directed arm and hand movements. Methods.The Virtual Peg Insertion Test (VPIT) was administered to 121 healthy and 80 neurological subjects. The framework provides 25 kinematic and kinetic metrics expected to describe 12 sensorimotor components representative of ataxia and paresis and their influence on task performance, as well as one overall disability measure. The feasibility (protocol duration), structural validity (factor analysis and correlations ρ between sensorimotor components), concurrent validity (correlation with Action Research Arm Test; ARAT), and discriminant validity (comparing healthy controls and patients, and patients with different disability levels) were evaluated. Results. The median VPIT protocol duration was 16.5min in neurological patients. The sensor-based metrics could unambiguously be grouped into 12 mostly independent (median |ρ|=0.14) components. Ten components showed significant differences between healthy and impaired subjects and nine components indicated clear trends across disability levels, without any ceiling effects. The VPIT overall disability measure Technology-based Upper Limb Disability Assessment and ARAT were moderately correlated (ρ=−0.53, p<0.001). Conclusions. This work demonstrates the possibility to rapidly, holistically, and objectively assess proximal and distal sensorimotor impairments and their influence on the capacity to perform activities with a single assessment.

An Objective Functional Evaluation of Myoelectrically-Controlled Hand Prostheses: A Pilot Study Using the Virtual Peg Insertion Test

“…The number of repetitions the VPIT could be successfully completed (i.e., insertion of all nine pegs) with a prosthesis was measured. The objective assessment with the VPIT was based on a previously defined computational framework, which relies on kinematic, kinetic, and haptic data that is processed into 12 mostly independent metrics describing sensorimotor impairments and their influence when performing coordinated, goal-directed arm and hand movements [17]. The metrics were selectively calculated during the transport (i.e., after picking up a peg until approaching a hole), return (i.e., after inserting a peg until approaching the next peg), peg approach (i.e., from targeting a peg until picking it up), hole approach (i.e., from targeting a hole until peg insertion), and force release (i.e., maximal release of force) phases.…”

“…All measures were averaged across pegs as well as repetitions and subsequently normalized with respect to the median and variability of a reference population (i.e., data from 120 neurologically intact subjects) [17]. Subsequently, each metric was further normalized with respect to the neurologically impaired subject that indicated maximal disability for this metric, chosen from a representative cohort of 80 neurological subjects.…”

“…This led to values in the interval ]−inf, inf[ with the median of the reference population being at 0% and the worst observed subject at 100%. Lastly, the influence of confounding factors such as age, gender, handedness, and tested body side was removed [17].…”

“…The goal of this pilot study was to explore the feasibility of using the Virtual Peg Insertion Test (VPIT) as a technology-based assessment for upper limb prostheses. The VPIT provides a rapid, standardized, kinematic-and kinetic-based evaluation of arm-and hand-control during a goal-directed manipulation task and was developed to assess sensorimotor profiles of upper limb disability in neurological patients [16,17]. We hypothesized that amputees using technically advanced (i.e., allowing precise grasping force control) prostheses could successfully complete the VPIT protocol.…”

“…1) consists of a virtual reality (VR) environment that can be controlled through a commercial haptic end-effector (Phantom Omni or Touch, 3D Systems, CA, USA) with a rapid-prototyped force sensing handle that contains three flexible parallel structures equipped with piezoresistive sensors (CentoNewton40, EPFL, Switzerland). The test was described in detail in previous work [16,17]. In short, the VPIT requires the coordination of arm movements, precise manipulations, and a stable grip to transport nine virtual pegs into nine holes, thereby mimicking a goaldirected manipulation activity.…”