Quantifying long-term upper-limb activity using wearable motion sensors after nerve reconstruction for neonatal brachial plexus palsy

Abstract

OBJECTIVE Standard, physician-elicited clinical assessment tools for the evaluation of function after nerve reconstruction for neonatal brachial plexus palsy (NBPP) do not accurately reflect real-world arm function. Wearable activity monitors allow for the evaluation of patient-initiated, spontaneous arm movement during activities of daily living. In this pilot study, the authors demonstrate the feasibility of using body-worn sensor technology to quantify spontaneous arm movement in children with NBPP 10 years after nerve reconstruction and report the timing and magnitude of recovered arm movement. METHODS Eight children with NBPP who underwent brachial plexus reconstruction approximately 10 years prior were recruited to take part in this single-institution prospective pilot study. Per the treatment protocol of the authors’ institution, operated patients had severe, nonrecovering nerve function at the time of surgery. The patients were fitted with an activity monitoring device on each of the affected and unaffected arms, which were worn for 7 consecutive days. The duration (VT) and power (VM) with which each arm moved during the patient’s normal daily activities were extracted from the accelerometry data and ratios comparing the affected and unaffected arms were calculated. Demographic data and standard physician-elicited clinical measures of upper-extremity function were also collected. RESULTS Three children underwent nerve grafting and transfer and 5 children underwent graft repair only. The mean (± SD) active range of motion was 98° ± 53° for shoulder abduction, 130° ± 24° for elbow flexion, and 39° ± 34° for shoulder external rotation. The median Medical Research Council grade was at least 2.5 for all muscle groups. The median Mallet grade was at least 2 for all categories, and 13.5 total. The VT ratio was 0.82 ± 0.08 and the VM ratio was 0.53 ± 0.12. CONCLUSIONS Wearable activity monitors such as accelerometers can be used to quantify spontaneous arm movement in children who underwent nerve reconstruction for NBPP at long-term follow-up. These data more accurately reflect complex, goal-oriented movement needed to perform activities of daily living. Notably, despite severe, nonrecovering nerve function early in life, postsurgical NBPP patients use their affected arms more than 80% of the time that they use their unaffected arms, paralleling results in patients with NBPP who recovered spontaneously. These data represent the first long-term, real-world evidence to support brachial plexus reconstruction for patients with NBPP.