Body-Worn Sensor Technology Captures Patient-Initiated Spontaneous Arm Movement after Reconstructive Surgery for Brachial Plexus Injury
Susan H Brown, PhD; Tanu Bhargava, MS; Serena J Saake, BS; Denise Justice, OTRL; Lynnette Rasmussen, OTRL; Kate Wan-Chu Chang, MA, MS; Samuel J Hertz, BS; Kevin C. Chung, MD, MS; Lynda Yang, MD, PHD; University of Michigan, Ann Arbor, MI
Introduction: Clinical assessment of function following reconstructive surgery for brachial plexus injury typically includes physician-elicited range of motion, muscle strength and self-reported disability. However, to what extent these measures predict patient-initiated arm movement following nerve reconstruction surgery is unclear. Recent advances in body-worn sensor technology provide a means of monitoring actual arm use in naturalistic settings following surgical reconstruction in this population. Methods: Clinical assessments of arm function (active range of motion (AROM), strength (MRC scale), and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire were completed on 10 patients (> 1 yr post-surgery, mean age: 43 y) who underwent either nerve transfer (n=7) or free functioning muscle transfer (FFMT, n=3) for brachial plexus injury. Patients then wore accelerometers (GT9X ActiGraph) on each wrist during waking hours for 7 consecutive days. The accelerometers measured arm motion in three planes and data were analyzed using ActiLife 6.13. Results: Compliance was excellent with an average weekly wear time of 110 hours. No adverse effects related to wearing the devices were reported. The mean ratio of arm use magnitude in the nerve transfer patients was .62 indicating that the amount of affected arm movement was 62% of the unaffected arm. In contrast, arm magnitude ratio was only .27 in the FFMT group. In the nerve transfer group, affected arm use was correlated with both biceps strength (r=0.79) and elbow AROM (r=0.81). A very strong correlation was observed between arm use and DASH scores was observed (r=0.93). No correlations were seen in the FFMT group. Conclusions: We demonstrate that body worn sensor technology is a feasible approach to monitoring "real world" arm use in patients following surgery for brachial plexus injury. We suggest that our results support the continued use of nerve reconstruction for brachial plexus injury in the appropriate patients. In contrast, our preliminary results do not support the use of free muscle transfers for patients with total brachial plexus injury, but further research involving a larger patient sample is warranted.
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