Project Details

Chronic pain in children with obstetrical brachial plexus palsy

Kristen Davidge, MD, MSc, FRCS(C)

Summary

BACKGROUND: Obstetrical brachial plexus palsy (OBPP) is a condition where the nerves innervating the upper limb are injured during the birthing process, resulting in immediate and often persistent impairment in upper limb sensory and motor function. The fact that children with OBPP experience pain has only recently been recognized, because children with OBPP do not start reporting pain in their affected upper limb until late childhood or adolescence, a decade or more after the initial nerve injury. GAP: Early data suggests that upper limb pain in older children and adolescents with OBPP is typically frequent, episodic, of low-to-moderate intensity and more common than initially recognized, with a point prevalence of 25% and lifetime prevalence of 66%. However, existing data are limited to operated patients and much remains to be understood regarding the nature of pain in this condition. HYPOTHESIS: The goal of this proposal is to establish the overall prevalence, characteristics, impact and determinants of pain in children and adolescents with obstetrical brachial plexus palsy. We anticipate overall point and lifetime pain prevalence to approach 15% and 50%, respectively, and hypothesize that children with OBPP experience episodic upper limb pain, with mixed musculoskeletal and neuropathic symptoms that interferes with function when the intensity is severe. METHODS: This study comprises a cross-sectional investigation of pain prevalence, characteristics, and interference, (Aims 1 and 2), and a retrospective cohort analysis of pain determinants (Aim 3). In the cross-sectional study, we will sample 684 children and adolescents with OBPP, aged 8-18 years, at a single, high-volume, pediatric tertiary care center. RESULTS: Of 684 eligible children, we had 202 respondents with a response rate of 30%. The prevalence of pain at time of survey completion was 42% in the affected upper limb. One hundred and eighteen children (58%) endorsed prior pain in their affected upper limb, and 145 (72%) children reported that their affected limb felt different. Survey responders had higher injury severity than non-responders, but were no different in terms of age, sex and limb injured. One-hundred and four of 123 eligible children (mean age 14.6 ± 3.2 years, 66% female) completed the in-depth pain assessments. Mean age of pain onset was 8.0 ± 1.6 years and mean pain intensity was 39.9 ± 21.5 mm (range, 0 to 80.5 mm). Pain was typically intermittent, with children utilizing a combination of neuropathic and musculoskeletal descriptors. The shoulder was the most frequently circled pain location, endorsed by 70% of children, followed by the elbow and hand at 28% each. Eight-four children (81%) reported that their pain sometimes, often or always impacted at least one of 11 different activities on the PI-PPQ; “sports”, “sleeping”, “seeing friends” and “enjoying the family” were the most commonly affected activities. In regression analyses, age at pain assessment and cervical root avulsion were significant predictors of having pain in OBPP, whereas increased injury severity (root avulsion, total plexus palsy, shoulder impairment) were predictive of worsened pain intensity in OBPP. IMPACT: This research has generated key information about the prevalence, characteristics, impact and predictors of pain in OBPP. Results will be used to guide improved recognition and diagnosis of pain in OBPP, and to guide further research that will improve treatment and prevention strategies based on knowledge of pain mechanisms. In the long-term, research on pain in OBPP will have wide-ranging implications for our understanding of central and peripheral pain processing in the neonate.