Intervention to enhance skilled arm and hand movements after stroke: A feasibility study using a new virtual reality system
© Stewart et al; licensee BioMed Central Ltd. 2007
Received: 13 March 2007
Accepted: 23 June 2007
Published: 23 June 2007
Rehabilitation programs designed to develop skill in upper extremity (UE) function after stroke require progressive practice that engage and challenge the learner. Virtual realty (VR) provides a unique environment where the presentation of stimuli can be controlled systematically for optimal challenge by adapting task difficulty as performance improves. We describe four VR tasks that were developed and tested to improve arm and hand movement skills for individuals with hemiparesis.
Two participants with chronic post-stroke paresis and different levels of motor severity attended 12 training sessions lasting 1 to 2 hours each over a 3-week period. Behavior measures and questionnaires were administered pre-, mid-, and post-training.
Both participants improved VR task performance across sessions. The less impaired participant averaged more time on task, practiced a greater number of blocks per session, and progressed at a faster rate over sessions than the more impaired participant. Impairment level did not change but both participants improved functional ability after training. The less impaired participant increased the number of blocks moved on the Box & Blocks test while the more impaired participant achieved 4 more items on the Functional Test of the Hemiparetic UE.
Two participants with differing motor severity were able to engage in VR based practice and improve performance over 12 training sessions. We were able to successfully provide individualized, progressive practice based on each participant's level of movement ability and rate of performance improvement.
Neurorehabilitation after stroke may include interventions designed to improve functional upper extremity (UE) skills through task-related practice. While amount of practice is an important variable for motor learning , variations in direction, timing and speed are needed to optimize the development of skill . Virtual reality (VR) is a promising modality for the creation of favorable practice environments for neurorehabilitation [3–8].
The purpose of this pilot trial was to determine the feasibility of providing individualized, progressive practice of skilled UE arm and hand movements after stroke using VR based tasks. We developed 4 tasks that allowed control of multiple parameters for the purpose of promoting motor skill learning by varying movement direction and speed. We investigated the feasibility of implementing an intervention tailored to each individual's level of movement ability and rate of progression over 12 practice sessions. Preliminary results are reported for two participants with different motor severity.
Participant Demographic Information
Level of Motor Severity
Time Since Stroke (months)
Type of Stroke
Side of Lesion/Paretic Limb
Hand Dominance Prior to Stroke
Virtual Reality System and Environment
Behavioral assessments were administered pre-, mid-, and post-training. Severity of motor deficit was determined with the UE portion of the Fugl-Meyer (FM) , an impairment-based measure. Functional ability was evaluated with the Functional Test of the Hemiparetic UE (FTHUE)  where the individual completes progressively more difficult functional tasks and the Box and Block test (B&B)  which requires one to grasp and move 2.5 cm blocks over a 10.8 cm tall barrier. The Stroke Impact Scale (SIS) was administered pre- and post-training to assess participation and health status .
Each participant attended 12 training sessions lasting 1–2 hrs/day over 3 weeks. A physical or occupational therapist was present during each session to run diagnostic tests and chose practice blocks and task parameters with the goal to maintain a moderate level of difficulty. If necessary, the therapist provided assistance for task completion, protected joint structures, and/or promoted movement quality.
VR Task Performance
Both participants completed all 12 VR practice sessions. Subject 102 (more impaired) was unable to perform 'Pinch' and required physical guidance to complete the other three tasks. Subject 103 (less impaired) practiced all four tasks independently with only occasional assistance. Subject 103 had 18.5% more total training time (7.95 vs. 6.48 hours) and averaged more time on task (39.76 ± 9.38 vs. 32.40 ± 9.3 minutes) and performed a greater number of practice blocks (16.17 ± 4.71 vs. 4.67 ± 1.50 blocks) per training session than did Subject 102.
Time in Seconds to Complete 'Reaching' Blocks Early and Late in Practice
30% Arm Length
50% Arm Length
For 'Rotation', both participants began practice on Day 1 with blocks targeting 45° of supination based on diagnostic results. By Day 12, Subject 103 performed blocks targeting a larger supination range (90°) while Subject 102 continued with practice targeting 45°. Finally, Subject 103 was able to practice 'Pinch' while Subject 102 could not. Subject 103 practiced grasping and lifting cubes of various sizes (20 & 40 mm) and weights (50, 100, & 150 g) to the maximal lift height (80 mm).
Summary of Behavioral Measures
UE FM Motor Score
Box & Block**
(Mean # Blocks)
SIS Hand Domain
In this report, we describe a newly developed VR system designed to promote UE movement skill in individuals recovering from hemiparesis. Two participants with differing motor severity were able to engage in VR based practice and improve performance over 12 training sessions. We were able to successfully tailor and progress practice content and task difficulty based on each participant's level of movement ability and rate of performance improvement. The feedback provided by the system was useful to the supervising therapist in setting goals, monitoring change in performance, grading task difficulty, and demonstrating performance change to the participant.
Others have reported improvement in UE movement capability in individuals recovering from stroke after training in a virtual environment. Merians et al. [6, 16] found improvements in hand function following 2 to 3 weeks of training on VR tasks. The tasks used in those studies focused primarily on hand and finger ability. Our system includes only one task that addresses hand function ('Pinch'), specifically a thumb and index finger pinch, with additional requirements that the grasp be coordinated with a reach movement. Holden et al. [5, 17] also demonstrated improved UE function in individuals post-stroke after training reaching movements in a virtual environment. The system used by Holden et al. [5, 17] made use of a "virtual teacher" to demonstrate optimal task completion and provide guidance to the user. We did not provide guidance during task performance but provided summary feedback at the completion of each practice block (10 to 20 trials) in order to engage the participant in anticipatory motor planning and problem solving throughout practice.
The VR system and tasks described in this pilot study provided a challenging practice environment that allowed individually-tailored practice progression. Future work is underway to further validate task design and configuration, develop hypothesis-driven algorithms for optimal task progression, evaluate transfer and persistence of training to real world activities, and incorporate more gaming features.
This work was supported by the Interdisciplinary Study of Neuroplasticity and Stroke Rehabilitation (ISNSR), an NIH Exploratory Center for Interdisciplinary Research (Grant # P20 RR20700-01) and the Integrated Media Systems Center, an NSF Engineering Research Center (Cooperative Agreement # EEC-9529152), both at the University of Southern California. The authors thank clinician therapists Cindy Kushi, Patricia Pate, Erica Pitsch, and JoAnne DelosReyes for assistance with data collection.
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