Effectiveness of botulinum toxin injection on upper-limb motor function of children with OBPP

Abstract

Obstetrical brachial plexus palsy (OBPP) is often complicated by contractures of shoulder internal rotators and/or co-contractions of the biceps/triceps brachii muscles. They are responsible of early limitations of the upper limb movements and thus limit children at the activity and participation level. The aim of this study was to evaluate the effect of botulinum toxin injections (BTI) on the active movements of the upper limb. Eighty-three children with C5-C7 injury received BTI with an average age of 4.2 years (ET: 55 months): 39 children in the intern rotators (IR), 44 in the triceps brachii (TB). The primary outcome measure was the Mallet scale at baseline, 3 months followed by a measure at 6 months of ITB. Comparisons using paired t -test were used to assess the statistical significance of the between-group differences. Sub-group analysis on different variables were carried out (age, gender, Mallet sub-score…). For the RI group, the total Mallet score increased significantly at 3 months (+4.3 on average out of a maximum score of 25) and remained significantly greater at 6 months (+2.6) compared to baseline with a greater improvement on the abduction task. For the TB group, the total Mallet score increased significantly at 3 months (+3.8) and remained significantly greater at 6 months (+2.6) compared to baseline with a greater improvement during the hand to mouth task. This study suggests that ITB is likely to improve the motor function of the upper limb of children with OBPP as it has been previously suggested in studies involving smaller groups. It also suggests a specific functional effect depending on the site of the injections and a prolonged effect until 6 months. Randomized controlled trials are needed to definitely confirm these preliminary results.