Botulinum toxin-a injections in children with cerebral palsy: functional outcome and characteristics of best responders

Botulinum toxin-a injections in children with cerebral palsy: functional outcome and characteristics of best responders

Botulinum Toxin A (BtA) injections in selected spastic muscles of children with cerebral palsy (CP) have shown a temporary beneficial effect in a limited number of recent studies.
However the long or medium term functional gains from this intervention have not yet been established.

The aim of this on going prospective study is to analyse the functional benefits of children with CP, within the first year after BtA injections.

Materials and Methods

Thirty eight CP children (tetraplegia=23, hemiplegia=5) with ages ranging from 3 to 9 years (mean: 4,5 yrs) enrolled in a physiotherapy (P.T.) program from early on and having no acute indication for orthodaedic surgery, were selected for intervention.
The functional goal was to help initiate, assist or improve one of the basic motor milestones i.e. sitting, standing, walking and running depending on the degree of individual involvement.
This latter was classified by the Gross Motor Function Classification System for C.P. BtA (Dysport, UK) was injected intramuscularly in selected spastic muscles of the lower extremities in all patients, using clinical localization or a neurostimulator.
A max dose of 40 U/kgr/per patient (Equivalency Ratio Dysport / BOTOX 3-4:1) was applied.
All children were evaluated in the immediate pre-interventional period and at 1,2 weeks and at the 1st, 3rd, 6th, 9th and 12 month thereafter, by neurological, orthopaedic, physical therapy examinations and detailed vidiorecordings.

Outcome measures included:

1) Clinical parameters as the degree of spasticity by the Ashworth scale (AS) and Passive range of motion at the involved joints by manual goniometry and
2) Functional measurements by the Gross Motor Function Measure test (GMFM).

Results:

  • All children tolerated well the procedure.
  • Mild transient side effects in the first week post injections were reported in four (10.5%). Some reduction of spasticity was noted within the first 1-4 days, reaching an observable effect by the end of 1st post treatment week in all children, while they continued P.T. The outcome results, combining clinical and functional parameters are reported as mean differences between baseline (pre-injection) period and at 3, 6, 9 and 12 months post treatment, taking into consideration a significance level of at least p<0.05 (Wilcoxon Statistics).
  • Significant gains, lasting over 9 mos were noted in 5 children (13%) (all ex-premies, ages 3-4 yrs, with spastic diplegia)
  • Moderate effects with significant improvement of clinical parameters in 3 mos and further functional achievements, between 3-6 mos were noted in 23 children (60.5%)(tetraplegi 3/10, diplegia 16/23, hemiplegia 5/5).
  • Minor changes (improvement of clinical parameter in the first 3 mos with no real functional gains were recorded in 8 patients 21%) (tetraplegia 5/10, diplegia 2/23).
  • Minimal effect was demonstrated in 2 children (5.2%) with marginal improvement of all parameters only within the first month.
  • Both had mental retardation and seizures.

Conclusions:

  • BtA injections in selected spastic lower extremities muscles of CP children is a safe, well tolerated interventional method.
  • Most children can respond favorably by achieving and maintaining functional gains for at least 6 mos post-treatment.
  • These best responders are children with diplegia (especially the young ones) hemiplegia and mild tetraplegia with good intellect.
  • A small percentage of children might not benefit from the interventions if there is severe involvement and associated problems.
  • This paper draws attention to the careful selection of BtA pediatric CP candidates, through a comprehensive team evaluation.