Quantitative comparison of grasp and release abilities with and without functional neuromuscular stimulation in adolescents with tetraplegia

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Abstract
In this study, a functional neuromuscular stimulation (FNS) hand system designed by Case Western Reserve University (CWRU) was implemented in 5 adolescents with C5 tetraplegia and hand function with FNS was evaluated and compared to tenodesis abilities using a grasp and release test designed specifically for this purpose. The test involved the unilateral acquisition, movement and release of 6 objects of various sizes and weights. During a single test session, five 30-second trials were performed with each object with and without the FNS system where the number of completions and failures were recorded for each trial. At least 4 and as many as 8 test sessions were conducted with each subject over periods of 1.5 to 3 years. For each subject, test performance with FNS was compared statistically to tenodesis performance and session-to-session consistency was analyzed. Of 30 comparisons (5 subjects and 6 test objects), FNS was more effective in 23 cases (77%), tenodesis was better in 5 instances (17%) and in 2 cases (6%) there was no difference. Subjects were able to manipulate the 3 heaviest test objects only with FNS and in 60% of all cases involving the 3 lighter test objects there were significantly more trials in which there were more completions or fewer failures with FNS. Performance with FNS and tenodesis was generally inconsistent across sessions; possible reasons for these variations are discussed. Overall, the results of this study support those of the only previous investigation that used the grasp and release test to evaluate hand function with FNS in C5 and C6 tetraplegia.