Functional Electrical Stimulation During Walking in Cerebral Palsy

Functional Electrical Stimulation of the Ankle Dorsiflexors During Walking in Children With Unilateral Spastic Cerebral Palsy: a Randomized Crossover Intervention Study

Children with spastic cerebral palsy (CP) often walk with insufficient ankle dorsiflexion in the swing phase. 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. 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, leading to restrictions in participating in daily life. The current guideline for spastic cerebral palsy describes the following therapies: 1) conservative therapy (physiotherapy, orthopaedic shoes and orthoses) 2) drugs suppressing spasticity 3) surgical interventions. 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 reduces falls and these effects also sustain. However, it should be noted that the level of evidence is limited. 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. Next to that the effect at gait will be measured. An additional goal is to investigate the cost effectiveness of FES, which, in case of a positive effect, may support allowance by insurance companies.

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.

randomisation for the order of treatments and thereby for the total length of the 'conventional therapy phase'.

The physical examination and the advanced analysis of the 3D gait analysis will be done be a blinded examiner.

Start: 4 weeks 'adaptation phase' and 8 weeks 'FES phase'. Adaption phase: the stimulus (in Volt) will gradually be increased up to an effective level and the wear time has to be increased from 30 minutes to 6 hours a day. FES phase: the participants have to wear the FES device for minimal 6 hours a day during walking. Usual physiotherapy can be continued during the FES phase. Second: after the FES phase, this group will enter the 'wash-out' period of 6 weeks for fading of the therapeutic effects, in which they return to their conventional therapy. Afterwards, 12 weeks of conventional therapy (orthoses/shoes and usual physiotherapy) with measurements at start and end will follow.

Start: wearing usual orthoses/shoes on a daily basis for the first 12 weeks of the study. Usual physiotherapy can be continued. Second: after 12 weeks this group will enter a 6 week watch out phase, and next be switched to FES treatment for 12 weeks, consisting of: 4 weeks 'adaptation phase' with gradual increase of the treatment and 8 weeks 'FES phase'.

Functional electrical stimulation of the ankle dorsiflexors during walking, using a (superficial) neurostimulator with tilt sensor.

Goal attainment scale: definition of an individual goal at start, followed by a 6- point numeric scale indicating to what extent the goal is (score 0 till +2) or is not (-3 indicating detoriation till -1) reached.

Measured by the 6 minute walking test and the functional mobility scale (3 items, 6-point rating scale).

the FES devices measures this automatically during wearing; so this will happen during the 12 weeks of FES therapy

Assessment and analysis of available imaging will be done after completion of the study by the patient, so after week 30, up to week 50 to collect a batch of finished patients. No imaging will be performed because of the study.

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

With publishing our results, an additional data file will be available containing the original individual data (anonymized) in order to make meta-analysis possible.

Moll I, Vles JSH, Soudant DLHM, Witlox AMA, Staal HM, Speth LAWM, Janssen-Potten YJM, Coenen M, Koudijs SM, Vermeulen RJ. Functional electrical stimulation of the ankle dorsiflexors during walking in spastic cerebral palsy: a systematic review. Dev Med Child Neurol. 2017 Dec;59(12):1230-1236. doi: 10.1111/dmcn.13501. Epub 2017 Aug 17.

Waters E, Davis E, Mackinnon A, Boyd R, Graham HK, Kai Lo S, Wolfe R, Stevenson R, Bjornson K, Blair E, Hoare P, Ravens-Sieberer U, Reddihough D. Psychometric properties of the quality of life questionnaire for children with CP. Dev Med Child Neurol. 2007 Jan;49(1):49-55. doi: 10.1017/s0012162207000126.x.

Moll I, Marcellis RGJ, Coenen MLP, Fleuren SM, Willems PJB, Speth LAWM, Witlox MA, Meijer K, Vermeulen RJ. A randomized crossover study of functional electrical stimulation during walking in spastic cerebral palsy: the FES on participation (FESPa) trial. BMC Pediatr. 2022 Jan 13;22(1):37. doi: 10.1186/s12887-021-03037-9.