Treating Spastic Equinus Foot from Cerebral Palsy with Botulinum Toxin Type A: What Factors Influence the Results?

Abstract

The aim of this study was to determine the variables that improve spastic equinus foot caused by cerebral palsy when treated with botulinum toxin type A. We reviewed all patients treated for spastic equinus foot using botulinum toxin type A (Botox) in the triceps suralis during a 3 1/2-yr period and analyzed the results after the first injection. There were 117 patients (72 diplegic and 45 hemiplegic patients) and a total of 189 triceps suralis treated. Variables analyzed included age, total dose per session, total dose per kilogram for each session, total dose per triceps, triceps dose per kilogram, type of cerebral palsy, cognitive level, botulinum toxin dilution, and physiotherapy. Assessments of efficacy were done using a Global Assessment Scale rated independently by parents, therapists, and a neurologist; the Modified Ashworth Scale; and the Modified Physician Rating Koman scale. Improvement was observed in all scales (P < 0.001). The change of foot position during walking was the best parameter for measuring improvement. There was correlation between the grade of improvement and the dose per kilogram for each triceps suralis (P < 0.001). Patient age was inversely correlated with improvement (P = 0.043). Diplegic and hemiplegic patients improved similarly, but the hemiplegic patients required higher doses for each muscle (P < 0.001). The most effective dose for diplegic patients was 3-4 IU/kg for each triceps, compared with 4-6 IU/kg for hemiplegic patients. Different dilutions of Botox (100, 50, and 40 U/ml) resulted in similar outcomes. No better results were achieved when 2-3 sessions/wk of physiotherapy was added to a daily program of exercises at home to enhance foot dorsiflexion. The dose per kilogram of Botox injected into triceps suralis and the patient age influence the results. The most effective dose is different between diplegic and hemiplegic patients. The concentration of botulinum toxin type A does not play a significant role in the outcome.