Botulinum toxin injections into psoas muscle – effect on leg lengthening in children with spastic hemiparesis

Background: Spastic hemiparesis in children is often combined with hyperlordosis, scoliosis and reduced leg length.

Aim: Does botulinum toxin injections into psoas muscle have effect on leg length?

Method: 25 patients (mean age 6,9 years; range:3–10 years) with spastic hemiparesis received 39 injections of botulinum toxin A or B as one-side multi-level treatment (psoas, gastrocnemius, soleus±medial hamstrings). 14 patients received one injection, 6 patients two and 4 patients three. Injections were performed sonography guided and under analgosedation. Dosage for psoas muscle were: 0,5–2,5 U/kg (mean 1,1 U/kg) Botox® or 35–50 U/kg Neurobloc® or 5 U/kg Dysport®. Leg length measurement was performed 4–6 weeks following the injections.

Results: 13 injections (1 injection for 7 patients, 2 injections for 3 patients) improved leg length by 0,5 (n=11) or 1cm (n=2). Dosage for psoas muscle in responders was 0,5–2,5 U/kg (mean:1,2 U/kg) Botox®.

Discussion: Leg length difference in children with spastic hemiparesis is not only a growth problem but also caused by psoas spastic. No significant higher dosage were found between responders and non-resonders. Evidence-based studies are needed to clarify ideal dosage and progress of leg lengthening after repeated psoas injections in children with spastic hemiparesis.