Germana Cappellini

Real-time assessment of spinal motor output (“spinal maps”) can provide insight into how neural control strategies during walking differ between healthy individuals and patients with neurological disorders. Abnormal spatiotemporal activation of spinal motor pools may underlie gait impairments, making spinal maps a potential physiological marker for guiding personalized rehabilitation. We present a stride-by-stride online visualization method for estimating spinal locomotor output from multi-muscle EMG signals mapped onto the approximate rostrocaudal location of motor pools, identifying activation patterns across lumbar and sacral motor pools. The primary objective of this framework is to serve as a near real-time neurophysiological monitoring and assessment tool during clinical gait analysis. Beyond this core diagnostic capability, the system is designed as an extensible platform that may support real-time feedback to therapists, exploratory biofeedback to patients, or future integration into closed-loop spinal neuromodulation protocols. The system enables online visualization of spinal maps and related parameters (such as timing, intensity, and coactivation of lumbar and sacral motor pools) through a flexible, user-friendly software interface. Preliminary tests in eight children with cerebral palsy and comparing with typically developing peers show that, despite stride-to-stride variability, the method may effectively differentiate in real-time impaired from typical spinal activation patterns, supporting its promise for clinical gait rehabilitation.

Aim: Understanding how haptic interaction supports interpersonal coordination during locomotion is important to develop assistive technologies when necessary. While significant work has been done on haptic interactions during adult locomotion, little is known about how children interact between each other or with an adult during walking. Here, we studied haptic-guided locomotion in children and adults. Methods: We examined 11 pairs (adult-adult, child-child [6–8 years old], and adult-child) walking side by side with hand contact toward targets, with one participant leading and one blindfolded follower. The walking path was either straight or curved. We recorded and analysed upper limb muscle electromyography, kinematics, and haptic interaction forces. Results and conclusion: All dyads (adult-adult, child-child, adult-child) showed relatively small interaction forces (around 3 N), which presumably function primarily as communicative cues rather than as direct mechanical drivers of movement of the partner. Gait initiation involved compliant interaction in all dyads, with frequent anterior deltoid shortening reactions aiding arm elevation and movement onset, particularly prominent in adult-child pairs. During curved locomotion, small direction-specific adjustments in force (2–3 N) and arm elevation (3–4) conveyed effective haptic cues across ages. In addition, we found clear age-related features in the haptic interaction. Adults reduced upper-limb compliance when guiding children as compared with guiding another adult. However, children were systematically more compliant when interacting with adults, irrespective of their role, leader or follower. We interpret this difference as indicating that adults emphasize precise control and interaction stability, whereas children display more variable and reactive motor behaviour. The latter behaviour may reflect the need of children to learn and explore while walking in tandem. However, it may also reflect a compliance control that is different from that of adults. Limitations: The sample size and children age range were limited. Moreover, we only included female adults.

Given the cervical spinal cord’s role in locomotor and rhythmic upper limb tasks, its neuromodulation has emerged as an important area of study for understanding human spinal rhythmogenesis. We previously demonstrated that, under unloading conditions, arm muscle vibrostimulation can elicit non-voluntary upper limb oscillations. In this study, we investigated the effects of transcranial magnetic stimulation (TMS) of the motor cortex during both voluntary and non-voluntary (vibration-induced) rhythmic arm movements. We analyzed motor-evoked potentials, mean arm muscle activity, and kinematic parameters of arm movements, including cycle duration and shoulder and elbow joint angular oscillations. Motor-evoked potentials in proximal arm muscles were significantly modulated during both movement types. Notably, low-frequency TMS markedly enhanced non-voluntary arm oscillations, whereas its effect on voluntary movements was statistically non-significant. This differential response is likely due to the absence of characteristic supraspinal influences in sensory-induced spinal activation during non-voluntary movements. These findings align with previous evidence showing that supraspinal pathways facilitate rhythmogenesis in the lower limbs, and they now extend this concept to the upper limbs. Overall, our results suggest that therapies aimed at modulating cervical central pattern generators may benefit from the active engagement of supraspinal motor circuits.

Given the cervical spinal cord’s role in locomotor and rhythmic upper limb tasks, its neuromodulation has emerged as an important area of study for understanding hu-man spinal rhythmogenesis. We previously demonstrated that, under unloading conditions, arm muscle vibrostimulation can elicit non-voluntary upper limb oscillations. In this study, we investigated the effects of transcranial magnetic stimulation (TMS) of the motor cortex during both voluntary and non-voluntary (vibration-induced) rhythmic arm movements. Motor-evoked potentials in proximal arm muscles were significantly modulated during both movement types. Notably, low-frequency TMS markedly enhanced non-voluntary arm oscillations, whereas its effect on voluntary movements was minimal. This differential response is likely due to the absence of characteristic supraspinal influences in sensory-induced spinal activation during non-voluntary movements. These findings align with previous evidence showing that supraspinal pathways facilitate rhythmogenesis in the lower limbs, and they now extend this concept to the upper limbs. Overall, our results suggest that therapies aimed at modulating central pattern generators in the cervical spinal cord may benefit from the active engagement of supraspinal motor circuits.

Cerebral Palsy (CP) is a leading cause of childhood motor disability, making independent walking a crucial therapeutic goal. Robotic assistive devices offer potential to enhance mobility, promoting community engagement and quality of life. This is an observational report of 22 cases of children with CP in which we evaluated the Moonwalker exoskeleton (a dynamic moving aid system) usability, functional changes, and caregivers' perspectives based on the International Classification of Functioning (ICF). All children (aged 2–8 years, with a severe gait impairment and inability to use a conventional walker) underwent Moonwalker training for 20 sessions, followed by home use for five months. Post-treatment, majority of children showed improved endurance assessed by the 10-m walk test with a notable involvement of the upper trunk and arm movements for gait assistance. Many of them achieved rather remarkable results reaching a velocity of ≥0.5 m/s given the constraints of the walking exoskeleton and the children's size, while at admission all children walked at a speed of less than 0.5 m/s. Several positive environmental factors and family adherence were noted, as assessed by ICF in a subgroup of children. This study on a sample of children demonstrated that the Moonwalker exoskeleton allows walking and training at home in children with severe CP, enhancing development, social interaction, and endurance, while being well-received by families.

Recent advances in the performance and evaluation of walking in exoskeletons use various assessments based on kinematic/kinetic measurements. While such variables provide general characteristics of gait performance, only limited conclusions can be made about the neural control strategies. Moreover, some kinematic or kinetic parameters are a consequence of the control implemented on the exoskeleton. Therefore, standard indicators based on kinematic variables have limitations and need to be complemented by performance measures of muscle coordination and control strategy. Knowledge about what happens at the spinal cord output level might also be critical for rehabilitation since an abnormal spatiotemporal integration of activity in specific spinal segments may result in a risk for abnormalities in gait recovery. Here we present the PEPATO software, which is a benchmarking solution to assess changes in the spinal locomotor output during walking in the exoskeleton with respect to reference data on normal walking. In particular, functional and structural changes at the spinal cord level can be mapped into muscle synergies and spinal maps of motoneuron activity. A user-friendly software interface guides the user through several data processing steps leading to a set of performance indicators as output. We present an example of the usage of this software for evaluating walking in an unloading exoskeleton that allows a person to step in simulated reduced (the Moon’s) gravity. By analyzing the EMG activity from lower limb muscles, the algorithms detected several performance indicators demonstrating differential adaptation (shifts in the center of activity, prolonged activation) of specific muscle activation modules and spinal motor pools and increased coactivation of lumbar and sacral segments. The software is integrated at EUROBENCH facilities to benchmark the performance of walking in the exoskeleton from the point of view of changes in the spinal locomotor output.

The forefoot plays an important role in providing body support and propulsion during walking. We investigated the effect of forefoot dysfunction on the gait pattern of a young adult with partial bilateral amputation of the toes. We measured our participant’s gait kinematics during barefoot and shod overground walking and analysed time-distance and joint range of motion (RoM) parameters against a group of healthy adults. Forefoot dysfunction gait is improved by footwear and walking experience; however, this improvement was still remarkably different (exceeded 95% CI) when compared to healthy gait at matching walking speed. Compared to healthy gait, walking barefoot had a slower speed and a 30% reduction in ankle and knee joint RoM, but a larger hip RoM. Shod gait resulted in a remarkable increase in ankle RoM and walking speed compared to barefoot gait. These results are consistent with the important role of the forefoot (tarsals and metatarsophalangeal joints) and suggest that footwear can facilitate gait function following toe amputation.

Surface electromyography (sEMG) can be used to assess the integrity of the neuromuscular system and its impairment in neurological disorders. Here we will consider several issues related to the current clinical applications, difficulties and limited usage of sEMG for the assessment and rehabilitation of children with cerebral palsy. The uniqueness of this methodology is that it can determine hyperactivity or inactivity of selected muscles, which cannot be assessed by other methods. In addition, it can assist for intervention or muscle/tendon surgery acts, and it can evaluate integrated functioning of the nervous system based on multi-muscle sEMG recordings and assess motor pool activation. The latter aspect is especially important for understanding impairments of the mechanisms of neural controllers rather than malfunction of individual muscles. Although sEMG study is an important tool in both clinical research and neurorehabilitation, the results of a survey on the clinical relevance of sEMG in a typical department of pediatric rehabilitation highlighted its limited clinical usage. We believe that this is due to limited knowledge of the sEMG and its neuromuscular underpinnings by many physiotherapists, as a result of lack of emphasis on this important methodology in the courses taught in physical therapy schools. The lack of reference databases or benchmarking software for sEMG analysis may also contribute to the limited clinical usage. Despite the existence of educational and technical barriers to a widespread use of, sEMG does provide important tools for planning and assessment of rehabilitation treatments for children with cerebral palsy.

Previous studies mainly evaluated the neuromuscular pattern generation in cerebral palsy (CP) during unobstructed gait. Here we characterized impairments in the obstacle task performance associated with a limited adaptation of the task-relevant muscle module timed to the foot lift during obstacle crossing. Impaired task performance in children with CP may reflect basic developmental deficits in the adaptable control of gait when the locomotor task is superimposed with the voluntary movement.