Deficits in Elbow Position Sense in Neonatal Brachial Plexus Palsy

BACKGROUND: In neonatal brachial plexus palsy, sensory recovery is thought to exceed motor recovery with little attention paid to long-term assessment of proprioceptive ability. However, there is growing evidence that reduced somatosensory function frequently accompanies motor deficits as a result of activity-dependent changes in the central nervous system. Given the importance of proprioception in everyday motor activities, this study was designed to investigate position sense about the elbow joint in neonatal brachial plexus palsy. METHODS: A convenience sample of seven individuals with neonatal brachial plexus palsy aged 9-17 years and in seven control individuals aged 10-16 years were recruited for the study. An elbow position matching task was used in which passive displacement of the forearm (reference arm) was reproduced with the same or opposite arm. In both conditions, matching was performed in the absence of vision and required utilization of position-related proprioceptive feedback. RESULTS: Position-matching errors were significantly greater for the affected versus the unaffected arm when reproducing a reference position with the same arm. When matching was performed using the opposite arm, errors were dependent upon which arm served as the reference arm. When the unaffected arm served as the reference position, affected arm matching errors were not significantly different from control values. However, in the reverse situation, in which the unaffected arm relied on reference feedback from the affected arm, matching errors doubled compared with control values. CONCLUSIONS: These results provide evidence that position sense is impaired in neonatal brachial plexus palsy and illustrate the importance of assessing proprioception in this population.