Functional Electrical Stimulation During Walking in Cerebral Palsy

Children with spastic cerebral palsy often walk with insufficient ankle dorsiflexion in the swing phase or with eversion of the foot. A pathological gait, known as drop-foot gait, can be the result and this has 2 major complications: foot-slap during loading response and toe-drag during swing. This is partly caused by weakness of the anterior tibial muscle and partly due to co-contraction of both the fibular- and anterior tibial muscle. In time, the disorder appears to be progressive due to atrophy and contractures of the muscle and increasing bodyweight. For classification of gait, the Winters scale can be used, where unilateral CP with dropfoot is classified as type I.

In daily life these problems cause limited walking distance and frequent falls. This can lead to restrictions in participating in daily activities at school and in leisure. The current guideline for spastic cerebral palsy describes the following therapies: 1) conservative therapy, which includes physiotherapy, orthopaedic shoes and orthoses. 2) systemically and locally applied drugs suppressing spasticity. 3) surgical interventions, e.g. tenotomy, transposition and osteotomy. In each intervention, there is the risk of side effects, such as sedation with oral medications, pressure sores and atrophy in a static orthosis, temporary effect in a Botulinum toxin A treatment and surgical complications due to a result of the surgery, and on the other hand as a result of the execution.

Functional electrical stimulation (FES) may be an effective alternative treatment for children with spastic CP and a drop foot. By stimulating the fibular nerve or the anterior tibial muscle directly during the swing phase, dorsiflexion of the foot is stimulated. In contrast to bracing, FES does not restrict motion, but does produce muscle contraction, and thus has the potential to increase strength and motor control through repetitive neural stimulation over time.

In a systematic review the investigators found that FES immediately improves ankle dorsal flexion and falls. In addition, longer sustained effects of FES on ankle dorsal flexion and falls are found. However, it should be noted only two study studies (4 articles) were of level II class evidence (small RCT) and all other studies used a single subject design. Until now, the use of FES in CP is limited and no data exist about the effects on walking distance (activity level) and participation level.

The overall objective of this study is to conduct a randomised cross-over intervention trial in children with unilateral spastic CP with 12 weeks of FES for every participant and 18 weeks of conventional therapy. The effectiveness of FES will be examined at participation leven, using individual goal attainment. With every individual a goal at walking distance will be set, next to possible other goals. Next to that, results will be measured at the activity and functional level: the effect at gait kinematics (such as ankle dorsiflexion and balance), walking distance, falls, spasticity and muscle force. The type of brain damage of the patients is also taken in to account. An addition al goal is to investigate the cost effectiveness of FES, which, in case of a positive effect, may support allowance by insurance companies.

Inclusion criteria

• Unilateral foot drop of central origin, particularly the absence of initial heel contact
• Participants are currently treated with ankle-foot orthoses or (adapted) shoes to wear on a daily basis
• Participants ambulate independently, and thus classified as Gross Motor Function Classification System (GMFCS) levels I or II and have a gait type 1 according to Winters et al (4).
• Participants are able to walk for at least 15 minutes
• Confirmed cerebral abnormality with MRI (showing medial infarction, maldevelopment of the brain, or porencephaly).
• Participants are aged 4-18 years at time of inclusion

Exclusion criteria

• Plantarflexion ankle contracture of more than 5 degrees plantarflexion with the knee extended
• Botulinum toxin A injection to the plantar or dorsiflexor muscle groups within the 6 months before the study
• Orthopaedic surgery to the legs in the previous year
• Uncontrolled epilepsy with daily seizures