Hand rehabilitation following stroke: a pilot study of assisted finger extension training in a virtual environment.(Clinical report)

Background and Purpose: The purpose of this pilot study was to investigate the impact of assisted motor training in a virtual environment on hand function in stroke survivors. Participants: Fifteen volunteer stroke survivors (32-88 years old) with chronic upper extremity hemiparesis (1-38 years post incident) took part. Method: Participants had 6 weeks of training in reach-to-grasp of virtual and actual objects. They were randomized to one of three groups: assistance of digit extension provided by a novel cable orthosis, assistance provided by a novel pneumatic orthosis, or no assistance provided. Hand performance was evaluated at baseline, immediately following training, and 1 month after completion of training. Clinical assessments included the Wolf Motor Function Test (WMFT), Box and Blocks Test (BB), Upper Extremity Fugl-Meyer Test (FM), and Rancho Los Amigos Functional Test of the Hemiparetic Upper Extremity (RLA). Biomechanical assessments included grip strength, extension range of motion and velocity, spasticity, and isometric strength. Results: Participants demonstrated a significant decrease in time to perform functional tasks for the WMFT (p = .02), an increase in the number of blocks successfully grasped and released during the BB (p = .09), and an increase for the FM score (p = .08). There were no statistically significant changes in time to complete tasks on the RLA or any of the biomechanical measures. Assistance of extension did not have a significant effect. Discussion and Conclusion: After the training period, participants in all 3 groups demonstrated a decrease in time to perform some of the functional tasks. Although the overall gains were slight, the general acceptance of the novel rehabilitation tools by a population with substantial impairment suggests that a larger randomized controlled trial, potentially in a subacute population, may be warranted. Key words: hand, finger extension orthosis, stroke, virtual reality

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Approximately 60% of stroke survivors experience upper extremity dysfunction limiting participation in functional activities. (1) Chronic deficits are especially prevalent in the hand. In fact, finger extension is the motor function most likely to be impaired. (2) This distal limb impairment is especially problematic, because proper hand function is crucial to manual exploration and manipulation of the environment. Indeed, loss of hand function is a major source of impairment in neuromuscular disorders, frequently preventing effective occupational performance and independent participation in daily life.

Several intervention approaches have been used in an effort to treat impairment and enhance functional recovery following stroke. Evidence indicates treatment techniques incorporating repetitive use of the affected limb, massed practice, task-oriented re-education, and constraint-induced movement therapy are the most effective strategies to date to improve motor recovery of the upper extremity. (3,4) Their use is further supported by observations from animal models of stroke in which practice seems to be the primary factor leading to synaptogenesis and brain plasticity) 7 Functional magnetic resonance imaging and transcranial magnetic stimulation studies in humans provide evidence for functional adaptation of the motor cortex following injury, (8-12) Imaging performed after constraint-induced training protocols has shown evidence of cortical plasticity as well. (13,14) Furthermore, many studies have demonstrated that neuroplasticity can occur even in the chronic stages of stroke. (14-18)

Rehabilitation is more effective when individuals are allowed opportunities for massed practice in a task-oriented context. (4) Robotics emerged in an effort to provide opportunities for this massed practice, which may be difficult for therapists to provide due to time and staffing limitations. For example, in lower extremity rehabilitation, body-weight-supported treadmill training has been found to be effective for individuals with decreased sensorimotor control. (19,20) However, this type of treadmill training is labor intensive, requiring assistance from up to three therapists for walking. Robotic machines have been introduced to assist with this task and to, ideally, make this treatment more readily available to clients. (21) Similarly, for the upper extremity, robots have been created to assist with therapeutic training of the arm and shoulder. (22) (25) Robotic devices have also been investigated as tools in upper extremity rehabilitation for chronic stroke survivors (20,24,26,27) in an effort to allow rehabilitation professionals to focus on functional independence and increased motor recovery for their clients. Research studies indicate that devices which incorporate intensive training of active repetitive movements increase upper extremity function following stroke. (20, 28-30) However, few devices have been designed specifically for hand rehabilitation, (31,32) especially for stroke survivors with moderate to severe impairments.

Robots and mechatronics also provide a convenient interface with virtual reality environments. These virtual environments have been recently applied to rehabilitation paradigms for stroke survivors. (31, 33-38) The use of virtual reality in rehabilitation affords the opportunity for individuals to practice movements in several different environments, allows rapid transition between tasks, and provides unlimited options for object sire, type, and location. Researchers have previously integrated a hand actuator with a virtual reality system for the purposes of rehabilitation after stroke, but the hand actuator was intended for individuals with relatively mild impairment and could not be used with real objects. (33,34,36-38)

In previous studies, we have found that individuals with moderate to severe chronic hemiplegia subsequent to stroke have directionally dependent weakness, such that finger extension is impaired to a greater extent than finger flexion. (39) Thus, we have developed two devices to assist finger extension when needed: a portable, cable orthosis (CO) with which the user could provide self-assistance, and a pneumatic orthosis (PO) that could provide automatic assistance. These devices were integrated with a virtual reality system. The purpose of this study was to explore whether repetitive practice with finger extension assistance could improve hand function in stroke survivors with moderate to severe upper extremity hemiparesis.

Method

Participants

A total of 15 adult participants (at least 1 year post stroke) with an average baseline Fugl-Meyer (40) score of 24 (see Table 1) volunteered to take part in this study. Participants had chronic upper extremity hemiparesis due to a stroke (7 [+ or -] 9 years post injury) and were classified as stage 2-3 on the Hand Subscale of the Chedoke McMaster Stroke Assessment, meaning that …