Effects of Functional Electrical Stimulation on Gait in Children With Cerebral Palsy

Effects of Functional Electrical Stimulation on Gait in Children With Hemiplegic and Diplegic Cerebral Palsy

Cerebral palsy (CP) is the most common neuromuscular disorder among children, resulting from a non-progressive injury during early brain development which leads to impairment of movement and posture.

Muscle weakness and spasticity associated with CP limit the joint range of motion and negatively impact ambulatory ability. Most ambulatory children with CP are prescribed with ankle-foot orthoses (AFOs) to improve ankle position and stability and to maintain muscle range. Nevertheless, AFOs may also restrict desired motions and may exacerbate muscle weakness and atrophy.

During the last years a novel method is being used for treating upper motor neuron drop foot, by means of dynamic orthoses, namely Functional Electrical Stimulation (FES).

These FES devices cause dorsiflexion of foot by stimulating the peroneal nerve and activating the tibialis anterior muscle. Most of the studies of FES devices were conducted on adult population. These studies showed improvement in laboratory and functional gait parameters. There are relatively few studies on children with hemiplegic or diplegic CP with favorable results. There is no solid evidence whether the improvements seen in laboratory setting of children with CP, are reflected on functional ambulation in daily life. In addition, there are no defined parameters which could predict the response to FES among those children.

The aim of this study is to determine whether using FES device (WalkAide; Innovative Neurotronics, Austin, TX, USA) improves daily motor function and gait parameters in children with spastic hemiplegic or diplegic CP. additionally, we aim to define clinical and biomechanical parameters that can predict a favorable response to using the FES device.

Cerebral palsy (CP) is the most common neuromuscular disorder among children, resulting from a non-progressive injury during early brain development which leads to impairment of movement and posture.

Individuals with CP exhibit a wide range of motor disabilities; however, approximately 70% of them achieve the ability to ambulate during childhood, albeit with difficulty.

Muscle weakness and spasticity associated with CP limit the joint range of motion and negatively impact ambulatory ability. The ankle joint is affected in virtually all patients. Insufficient ankle dorsiflexion during swing, foot drop and excessive plantar flexion during early to mid-stance may cause standing and walking instability with greater risk for falling. Most ambulatory children with CP are prescribed with ankle-foot orthoses (AFOs) to improve ankle position and stability for standing and walking and to maintain muscle range. Nevertheless, AFOs may also restrict desired motions and may exacerbate muscle weakness and atrophy, leading to further loss of function over time. In addition many children, especially adolescents, avoid using AFOs because of discomfort and concerns regarding negative effects on body image.

During the last years a novel method is being used for treating upper motor neuron drop foot, by means of dynamic orthoses, namely Functional Electrical Stimulation (FES).

These FES devices cause dorsiflexion of foot by stimulating the peroneal nerve and activating the tibialis anterior muscle.

FES devices, by actively stimulating the muscle have theoretical advantages over static AFOs. In addition the stimulator can be cosmetically better accepted.

Most of the studies of FES devices were conducted on adult population with upper motor neuron defect. These studies showed improvement in laboratory and functional gait parameters.In addition to the direct orthotic effect of the device during utilization, some studies also indicated a therapeutic effect ("carry over effect"), which was postulated to arise through the neural plasticity facilitation by increasing the strength of afferent feedback inputs to CNS. Whether this therapeutic effect actually exists and for how long is still unclear.

A variety of Functional Electrical Stimulation (FES) devices are being increasingly prescribed as a treatment option in CP children. There are relatively few studies on children with hemiplegic or diplegic CP. Prosser et al(Prosser et al 2013), reported good acceptability of FES device in CP population. Other studies have showed as well favorable results, with improvement of ankle kinematics parameters, such as dorsiflexion angle at swing phase and initial contact. Damiano et al (Damiano et al 2012) showed evidence of use-dependent muscle plasticity with increased tibialis anterior muscle thickness while using FES devices in CP patients.

There is still no solid evidence whether the improvements seen in laboratory setting are reflected on functional ambulation in daily life. Some studies showed improvement in walking speed while others did not.

Moreover, some studies also indicated an effect variability among subjects, which could be partially explained by the heterogeneity of CP population. There are no defined parameters which could predict the response to FES among those children.

The WalkAide(WalkAide; Innovative Neurotronics, Austin, TX, USA) is a battery-operated, small medical electrical stimulator device, which attaches to a molded cuff located just below the knee and produces controlled dorsiflexion of the foot during walk.It utilizes a tilt sensor and accelerometer to control the timing and duration of the stimulation during walking.Use of the Tilt Sensor to trigger stimulation eliminates the need for additional components or external wires.

The aim of this study is to determine whether using WalkAide device, improves daily motor function and gait parameters in children with spastic hemiplegic or diplegic CP. In addition, we aim to define clinical and biomechanical parameters that can predict a favorable response to using the FES device.

Inclusion Criteria:

-Children above age of 6 years, with hemiplegic and asymmetric diplegic CP GMFCS I/II, with drop foot and dynamic contracture of the ankle on examination, who are being treated at the CP clinic at Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.

Exclusion Criteria:

• Children with fixed contracture of ankle joint (passive range of motion< 0 degree); children who had orthopedic surgery to the leg or had botulinum toxin injection to the plantar or dorsiflexor muscles within the 6 months prior to the study; children who cannot tolerate the electrical stimulation delivered by the device.