314 Exoskeletons increase paretic limb use in stroke survivors during a bimanual virtual reality reaching task

OBJECTIVES/GOALS: Almost 8 million Americans live with disability caused by stroke. However, recent advances in stroke rehabilitation are costly and lack resemblance to activities of daily living. The goal of this study was to develop a rehabilitation platform to increase stroke patients paretic limb use using inexpensive virtual reality and exoskeleton devices. METHODS/STUDY POPULATION: We conducted a feasibility study with 2 hemiplegic stroke participants. They reached for targets in a virtual reality environment using both hands. They completed 162 reaches divided into 3 blocks. Following baseline, we used an exoskeleton to provide 50% arm weight compensation to the paretic limb and used wrist weights to provide 50% arm weight resistance to the non-paretic limb. We removed the exoskeleton and wrist weights during the retention block. We used electromyography to approximate muscle activity in the biceps brachii. Relative contribution (RC) was calculated as the displacement of the paretic arm divided by the sum of displacements for both arms. Muscle contribution (MC) was calculated as the root mean square of paretic arm muscle activity divided by the sum of activity for both arms. RESULTS/ANTICIPATED RESULTS: During baseline, RC of the impaired limb was 44% and 48%, and MC of the impaired bicep was 43% and 35% in two mild to moderately impaired patients (Fugl-Meyer Upper Extremity scores of 43 and 37, respectively). During loading, RC increased by 5.6% and 1.1% and MC decreased by 8.3% and 11.8%. These data suggest hemiplegic stroke participants alter limb coordination when our device normalizes muscular output asymmetries between limbs. Importantly, these results closely match data from our previous work in 12 healthy controls, where we found a 2% increase in RC is significantly predicted by a 11% decrease in MC. By collecting more data on stroke patients, we will quantify this tradeoff between coordination and muscle activity modulation, allowing us to optimize the exoskeleton mechanics to maximize paretic limb use. DISCUSSION/SIGNIFICANCE: We demonstrate our platform is well tolerated by mild to moderately impaired stroke patients; this feasibility study forms the basis for low cost at-home technologies for stroke rehabilitation. With further development, clinicians can use our platform to fine-tune the level of limb constraint based on the individual needs of the patient.