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Botulinum Toxin for the Treatment of Motor Imbalance in Obstetrical Brachial Plexus Palsy
Ehud Arad, MD; Derek Stephens, MSc; Christine G. Curtis, BScPT, MSc; Howard M. Clarke, MD, PhD
Hospital for Sick Children, Toronto, ON, Canada
Background: Residual muscle imbalance is a common problem affecting obstetrical brachial plexus palsy (OBPP) patients. Imbalance typically leads to limitations in shoulder abduction and external rotation, and in elbow flexion and supination. Ongoing imbalance may produce functional limitations or structural joint deformities, necessitating secondary surgical balancing procedures. The goal of this study was to examine the efficacy of Botulinum toxin-A (BTX-A) in improving muscle imbalance in OBPP patients.
Methods: We retrospectively reviewed all charts of OBPP patients treated with BTX-A for muscle imbalance as an isolated procedure. Collected data included details of patient demographics, nature and primary management of OBPP, BTX-A injection technique, secondary surgical procedures and Active Movement Scale (AMS) scores. Outcomes were examined by the change in AMS scores from pre- BTX-A scores to scores at 1 month post- BTX-A and 1 year post- BTX-A. Statistical analysis for change in AMS scores was performed by repeated measures analysis of variance. p values of 0.05 or less were considered to be statistically significant.
Results: From a population of approximately 600 new patients seen from 2004-2011, a study sample of 27 patients were included, of which 18 were treated for shoulder imbalance and 8 for elbow imbalance. Primary brachial plexus neurotization had been performed in 11 (58%) of shoulder patients and 6 (75%) of elbow patients. Age (months, mean±1SD) at first BTX-A procedure for the shoulder and elbow groups was 30.7±24.8 and 36.2±28.2, respectively. AMS scores (mean±1SD) for shoulder external rotation improved from 0.6±2.6 pre-BTX-A, to 2.6±2.14 (p < 0.01) at 1 month post-BTX-A, and declined to 1.3±1.2 (p < 0.01) at 1 year post-BTX-A. Scores for elbow flexion were 3.3±2.1 pre-BTX-A, unchanged at 4.4±1.8 (p = 0.07) 1 month post-BTX-A, and improved to 5.8±0.5 (p < 0.01) at 1 year post-BTX-A. Scores for elbow supination were 2.9±1.7 pre-BTX-A and 3.4±1.5 (p = 0.2) at 1 month post-BTX-A, and improved to 3.9± 2.0 (p < 0.01) at 1 year post-BTX-A. Secondary balancing surgeries were subsequently performed in 6 (32%) of shoulder patients but none of the elbow patients.
Conclusions: BTX-A for shoulder movement imbalance produces improvement in external rotation that is not sufficiently sustained over time to be of clinical benefit. However, BTX-A for elbow movement imbalance produces a sustained and clinically useful improvement in elbow flexion.
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