Cerebral palsy (CP)
Cerebral palsy (CP) is a collection of non-progressive conditions occurring due to cortical lesions of disorders an infant or even the developing infant (Wallard et al, 2017). Due to the CNS lesions, intrinsic functional compensatory strategies produce atypical gait and postural patterns: motor control adaptations. For instance, CP is associated with entire body stiffness, instability in the posture especially seen with the bloc patterns in the upper body which reduce trunk and head rotation in relation to the pelvic positioning. The upper body stiffness is a motor control adaptation that enables control and reduces lower extremity movement effects on the head, thus the head is stabilized when walking.
Gross Motor Function Classification System (GMFCS) is a standardized classification system used to describe the motor function in pediatric patients diagnosed with CP between 1 and 12 years. It has five levels that point to meaningful gross motor tasks with specific emphasis on walking and sitting, as part of the daily activities of living of both the patients and their families. The differences in the classes are based on the use of walking aids or wheeled devices, limitation of function, and movement quality. Age-based descriptions are also used with the clusters including; younger than 2 yrs., 2-4yrs, 4-6yrs, and 6-12 yrs.
In individuals with central nervous system disorders, variables such as the intensity of training, repetition levels with adaptation, specificity, and frequency are important in encouraging sensorimotor adaptation and learning (Ammann-Reifer et al, 2020). Training in conventional approaches often requires about 3 therapists for trunk and pelvis stabilization, and limb movement support is severe cases of cerebral palsy (CP), Parkinson’s, spinal cord injury, stroke, and multiple sclerosis. Robotic rehabilitation approaches alleviate the limitations in conventional approaches by decreasing the manual workload of the therapists and enabling longer durations and higher frequencies of repetition during training sessions. The utilization of robot-assisted therapy (RAT) becoming increasingly popular as an adjunct to traditional physical therapy in cerebral palsy. This might be because motor capabilities in terms of mobility are an important priority in terms of the choice of intervention among children and adolescents with CP and their parents (Aurich-Schuler, 2017).
Lokomat is a mechanical exoskeleton that is utilized in rehabilitation facilities proven to be feasible in both pediatric and adult patients suffering from cerebral palsy and other walking disorders. This has been a new and promising field in terms of rehabilitation of CP and stroke patients. However, controversies exist in its effectiveness with some studies supporting the superiority of robot-assisted approaches over conventional approaches, while others presenting a differing opinion. RAT offers a supportive, simplified, and safe environment for physical therapy with an allowance of visual aids and feedback which is ideal for the learning of movement and task performance. However, the supportive framework also confers a disadvantage since the full robotic support encourages passiveness among the patients which produces reduced activity and muscle hypotonia, inhibits adaptation of dynamic gait pattern, impairs functional participation, and adaptability to errors (Aurich-Schuler, 2017).
This paper will appraise two research articles with an aim of analyzing the positive impact of Lokomat therapy on gait impairment rehabilitation in children with CP.
Discussion
The Ammann-Reifer et al (2020) study used a randomized cross-over study that analyzed the effectiveness of robot-assisted gait training (RAGT) in improving the effective mobility parameter in a pediatric patient diagnosed with CP. The researchers used a single-blinded crossover study design, randomized at its interventions. Two outpatient settings were used: both pediatric rehabilitation centers in Switzerland. The inclusion criteria included pediatric patients with ages between 6 and 18 years, diagnosed with bilateral quadriplegic or diplegic spastic Cerebral palsy, and a GMFCS (Gross Motor Function Classification System) level of 2-4, with mobility capability of 14meters or more whether or not mobility aids are used. These participants represented a wide range of patients encountered in clinical settings, making the study results applicable in clinical practice. The exclusion criteria included participation in limb or trunk orthopedic surgery or neuro-surgery, or even a Lokomat intervention within the last six months and contraindications such as circulatory derangements, fractures and severe existing contractures outlines by the Lokomat instruction manual.
The participants were randomized into two pre-meditated intervention groups, conventional therapy (C) and RAGT (T). A participant belonged to either the TC or the CTC intervention groups. Members of the TC group were first assessed, exposed to 5 weeks of RAGT therapy, then exposed to a second assessment after which they were exposed to the conventional therapy (C) and finally a third assessment (11-week duration). The CTC group participants started with conventional therapy, followed by RAGT then another conventional therapy each lasting for a 5-week duration with 4 assessment points (16-week duration). RAGT sessions included 45-minute Lokomat sessions with a 3 times weekly frequency. VR (virtual reality) technology was also employed to increase training adherence, with the guidance force, speed, and support of body weight configured to individual child abilities. Conventional therapy involved 2 physiotherapy sessions weekly; involving occupational physiotherapies, circuit training, and hippotherapy.
Parameters used for the quantification and description of the Lokomat sessions included walked distance, duration, and the number of sessions, guidance force, gait speed, and percentage of supported body weight. The researchers used the percentage dimension E score of the GMFM-88 (Gross Motor Function Measure-88) that assess jumping, running, and walking tasks as the principal outcome measure. The GMFM is the gold-standard for gross motor function assessment in pediatric patients diagnosed with CP. Secondary outcome measures included the 10MWT (10-meter walking test) that assessed gait speed through a test-retest speed determination in a 14-meter track: the test is performed at both fast and comfortable self-selected pace. Measures of body function assess parameters such as muscle strength through manual testing of the muscles during flexion and extension, modified Ashworth scales, motion range, and 3D gait analysis. A 6MWT (6-minute walking test) was also used to assess the distance covered by requiring the participant to walk on a corridor 30 meters in length. The dimension D score GMFM-88 was also used to evaluate the participants’ ability to stand.
The results of the study showed no significant improvement in the GMFM E score after Lokomat therapy (-0.7) or conventional therapy (0). The follow-up, period, effects of treatment did not all show an observable impact: scores of 0.75, 0.91, and 0.61 respectively. For the secondary outcome measures, no significant change was observed apart from the 6MWT where a minimal change was observed (p= 0.22; Effect size (r) =0.23): the median change score was 11 for Lokomat and -0.5 for conventional therapy. This finding statistically insignificant improvements were explained by the fact that the participants with GMFCS-level 3-4 would only be expected to show slight improvements: in addition to the fact that the tests were conducted without walking aids and on barefoot. Wallard et al (2017) support this by noting clinically insignificant results were observed in studies with higher numbers of GMFCS scores of 3-4 (moderately severe to severe) whose mobility de[pends on walking aids. The researchers’ hypothesis based on previous evidence-based research was that RAGT therapy for 5 weeks would be superior to conventional treatment for 5 weeks with respect to gait rehabilitation impairments. This was however not confirmed due to the low statistical power due to the low participant number (16 participants out of the 34 intended participants. The authors however report that empirical evidence on Lokomat’s effectiveness is inconsistent and weak. They however report consistent findings with other studies that found no significant temporospatial and kinematic effects after 20 Lokomat sessions done in four weeks. The statistically significant changes in the 6MWT parameter were also observed in another study, where they increased in only in the Lokomat group: +21m.
The clinical interpretation of these results showing insignificant changes in the gait impairments is questionable. However, the superiority of the Lokomat RAGT in improving the distance a CP patient can walk compared to conventional therapies informed by the 6MWT measures warrants its clinical application. Ammann-Reifer et al (2020) recommend the incorporation of Lokomat RAGT together with other approaches as part of holistic care in clinical practice.
The Wallard et al (2017) study aimed to evaluate the effectiveness of Lokomat RAGT in improving dynamic control of gait equilibrium in CP patients by focusing on the various full-body postural adaptations, before and after RAGT. The study involved 30 pediatric patients of age range 8 to 10 years diagnosed with CP. The inclusion criteria included: pediatric patients with spastic diplegia disorder and a jump gait, able to walk or stand independently, or with use of walking aids and a GMFCS of 2 (moderate motor impairment severity). Exclusion criteria included exposure to a surgical CP intervention or botulinum toxin injections in the last 1 year.
The participants were randomized into two groups: the treatment group (TG) comprising of 14 participants (6 girls and 8 boys) who received 20 Lokomat RAGT sessions (5 weekly 40-minute sessions for 4 weeks), and the control group (CG) consisting of 16 participants (9girls and 7 boys) who only received physiotherapy sessions daily. For the intervention group, the parameters used in the Lokomat RAGT were participant body weight, tone of the muscles, lower limb motion range, and limb length measures. The support of the entire body weight at the starting point was 70% and was progressively reduced to 40% by the end of the session, while the gait speed was started at 0.7 km/hr and progressively raised to 1.4 km/hr. The control group’s psychotherapy regimen included 10 minutes of passivo-active segment mobilization, then subsequently posture-balance whole-body exercises involving tasks such as object displacements, grasping and walking on diverse grounds: total of 40 minutes.
The outcome measures for the study include a Vicon camera system with reflective marker sets, which recorded the 3D kinematic data of the entire body, clinical analysis of gait which analyzed the participants’ gait barefoot on a 10 m level walkway and GMFM-66 test whose dimensions D (standing) and E (climbing, running, and walking) analyzed the various motor skills such as postural stability and walking on various surfaces.
The following results were obtained from the research; the kinematic data shows that significant differences in both the upper (elbow, shoulders, and head) and lower body (ankle and knee) kinematic parameters between the treatment and control groups at the end of the intervention period: an intergroup comparison Mean peak angle p values of 0.005, 0.031, 0.046, 0.013, 0.035 and 0.026 for the head pitch, head roll, shoulder elevation, elbow, knee and ankle movements respectively. Significant improvements were observed in the GMFM-66 dimensions for both groups at the end of the treatment period: For dimension D TG= 60.58% versus CG= 55.74%; p-value= 0.048; for dimension E, TG=50.87% versus CG= 43.61%; p-value =0.026. The observed improvements in GMFM-66 dimensions were higher for the treatment group than the control group (dimension D TG 6.69% versus CG 1.93%; dimension E TG 8.64% versus CG 1.10%).
The observed result shows that in a clinical setting, pediatric patients on Lokomat therapy are able to acquire newer gait strategies than with the use of the convention physiotherapy approaches. The statistically significant improvements in the TG show better dynamic equilibrium gait control of the entire body. Adoption of new gait strategies is therefore expected to produce more relevant upper body control which translates to lower body function improvements (gait rehabilitation) when applied to clinical settings. The observed significant gains in the gait patterns especially the stance phase and initial contact angle of the ankle and knee represent positive steps towards functional gait rehabilitation achieved through repetitive and intensive simulation of various gait phases. The correlation between the significant improvements in both the kinematic and the GMFM E and D dimensions translates in reduced use and reliance on walking aids and improved alternating steps.
Conclusion
RAGT is beneficial in improving locomotor and postural functions in children diagnosed with CP. The improvements produce a gait pattern reorganization effect to resemble the normal developmental gait pattern observed in healthy children (Wallard et al, 2017).