Quantifying real-world upper limb activity via patient-initiated spontaneous movement in neonatal brachial plexus palsy.

Background: Neonatal brachial plexus palsy (NBPP) results in muscle weakness and impaired somatosensory function of the arm. Current functional assessment is primarily based on clinician-elicited measurements including muscle strength and range of motion. To what extent these measures are representative of real-world arm movement is unclear.

Objective: To determine the feasibility of using body-worn accelerometers to remotely assess arm movements in children with NBPP.

Design: Prospective criterion validity study of accelerometry versus clinician assessment.

Setting: Academic medical center.

Participants: Nine adolescents with NBPP and nine age- and gender-matched control adolescents participated in the study. All were enrolled in school and participated in community activities.

Interventions: Not applicable.

Methods: Standard clinician-elicited measurements were collected. For assessing spontaneous arm movements, participants wore activity monitors during all waking hours for 7 days. Results were expressed as ratios of affected to unaffected arm motion for duration and magnitude and correlated with traditional clinic-based assessments. Spearman correlations were used to determine relationships between accelerometry results and traditional assessments. A p value <.05 was considered statistically significant.

Main Outcome Measurements: Accelerometry measurements of arm motion and traditional clinical assessments.

Results: Compared to control ratios, duration of arm movement and magnitude ratios were reduced in the NBPP group, particularly for arm magnitude due to reduced affected arm movement and an increase in unaffected arm movement. Ratios were highly correlated with shoulder function and, to a lesser extent, with elbow function.

Conclusion: Real-world arm use is an appropriate outcome measure that reflects functional recovery. This study demonstrates the feasibility of wearable technology to quantify duration and intensity of spontaneous arm movement in children with NBPP. Accelerometry also allows for the association between traditional clinician-elicited assessment measures and spontaneous arm movements, demonstrating the importance of the shoulder as a focus of treatment in NBPP.