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The implementation of electromechanical devices for the quantification and treatment of movement impairments (abnormal muscle synergies, spasticity, and paralysis) resulting from brain injury is the main topic in this chapter. The specific requirements for the use of robotic devices to quantify these impairments as well as treat them effectively are discussed. A case is made that electromechanical devices not only allow the clinician to quantitatively control task practice and dosage, but, more importantly, allow for direct targeting of specific impairments, such as the loss of independent joint control (Dewald et al. Top Stroke Rehabil. 8(1):1–12, 2001), that are informed by a body of scientific evidence. Acceptance of these new technologies is dependent on proof of their effectiveness in the reduction of movement impairments and activity limitations, as opposed to compensation, and ultimately on carryover of benefits to activities of daily living and quality of life. Furthermore, the need of a concerted effort to simplify these new technologies, once essential treatment ingredients have been determined, is seen as being a key component for their acceptance in the clinic on a large scale. Finally, it is crucial that we demonstrate that electromechanical technologies augment existing rehabilitative care and serve to reduce treatment time and costs while maintaining, and even improving, functional outcomes. This is a requirement for future technology development especially in a healthcare environment where rehabilitation services have become less accessible.

In the rehabilitation of a patient suffering a spinal cord injury (SCI), the exploitation of neuroplasticity is well established. It can be facilitated through the training of functional movements with technical assistance as needed and can improve outcome after an SCI. The success of such training in individuals with incomplete SCI critically depends on the presence of physiological proprioceptive input to the spinal cord leading to meaningful muscle activations during movement performances. Some actual preclinical approaches to restore function by compensating for the loss of descending input to spinal networks following complete/incomplete SCI are critically discussed in this report. Electrical and pharmacological stimulation of spinal neural networks is still in the experimental stage, and despite promising repair studies in animal models, translations to humans up to now have not been convincing. It is possible that a combination of techniques targeting the promotion of axonal regeneration is necessary to advance the restoration of function. In the future, refinement of animal models according to clinical conditions and requirements may contribute to greater translational success.

Recent research indicates that a task-specific, interhemispheric neural coupling is involved in the control of cooperative hand movements required for activities of daily living. This neural coupling is manifested in bilateral electromyographic reflex responses in the arm muscles to unilateral arm nerve stimulation. In addition, fMRI recordings show a bilateral task-specific activation and functional coupling of the secondary somatosensory cortical areas (S2) during the cooperative, but not during bimanual control tasks. This activation is suggested to reflect processing of shared cutaneous input during the cooperative task in both cortical areas. In chronic poststroke patients, arm nerve stimulation of the unaffected arm also leads to bilateral electromyographic responses, similar to those seen in healthy subjects in the cooperative task. However, stimulation of the affected side is frequently followed only by ipsilateral responses. The presence/absence of contralateral electromyographic responses correlates with the clinical motor impairment measured by the Fugl-Meyer score. The observations suggest impaired processing of afferent input from the affected side leading to defective neural coupling during cooperative hand movements after stroke. In moderately affected patients, movement execution seems to rely on the involvement of the ipsilateral corticospinal tract arising in the non-damaged hemisphere. According to these results, hand rehabilitation of stroke patients, currently focused on reach and grasp movements of the affected side, should be supplemented with the training of cooperative hand movements required during activities of daily living.

The application of rehabilitation technologies in children with neurological impairments appears promising as these systems can induce repetitive goal-directed movements to complement conventional treatments. Characteristics of robotic-supported and computer-assisted training are in line with principles of motor learning and include high numbers of repetitions, prolonged training durations, and online feedback about the patient’s active participation. When experienced therapists apply these technologies, they can be considered a rather safe and in combination with virtual realities a motivating supplementary approach. Therapists might have to take into account that there might be some factors that are different when applying such technologies to children with congenital versus acquired neurological lesions. Currently, clinical guidelines on how to apply such technologies are missing, and clinical evidence considering the effectiveness of such technologies has just started to commence in pediatric neurorehabilitation. Experienced therapists formulated recommendations that might be useful to those with less experience on how to apply some of these systems to train the lower and upper extremity intensively and playfully. Finally, suggestions are made on how these technologies could be integrated into the clinical path.

Robots for neurorehabilitation have been designed principally to automate repetitive labor-intensive training and to support therapists and patients during different stages of rehabilitation. Devices designed for body weight-supported treadmill training are promising task-oriented tools intended to assist in the restoration of gait. In early rehabilitation, robots provide a safe environment through the use of a suspension harness and assistance in achieving a more physiological gait pattern while promoting a high number of repetitions. In the later stages of rehabilitation, more sophisticated control strategies, virtual environment scenarios, or the possibility to address specific gait deficits by modulating different parameters extends their application. Scientific and clinical evidence for the effectiveness, safety, and tolerability of these devices exists; however documentation of their comparative advantages to conventional therapies is limited.

In recent decades, several novel approaches of spinal cord repair have revealed promising findings in animal models. However, for a successful translation of these into a clinical trial in humans the specific conditions pertaining to human spinal cord injuries (SCI) have to be appreciated. Firstly, transection of the spinal cord is commonly applied in animal models, whereas spinal cord contusion is the predominant type of injury in humans, and generally leads to more extensive injury in two to three spinal cord segments. Secondly, the quadrupedal organization of locomotion in animals and the more complex autonomic functions in humans challenge the translation of animal behavior into recovery from human SCI. Thirdly, so far, no adequate animal model has been developed to resemble spastic movement disorder in human SCI. Fourthly, the extensive damage to spinal motor neurons and nerve roots in human cervical and thoracolumbar in spine trauma is but little addressed in current translational studies. This damage has direct implications for rehabilitation and repair strategies. Fifthly, there is increasing evidence for a neuronal dysfunction below the level of the lesion in chronic complete SCI. The relevance of this dysfunction for a regeneration-inducing treatment needs to be investigated. Lastly, an approach to facilitate an appropriate reconnection of regenerating tract fibers by functional training in the postacute stage has yet to be confirmed.

Neuroplasticity refers to the ability of the central nervous system (CNS) to undergo persistent or lasting modifications to the function or structure of its elements. Neuroplasticity is a CNS mechanism that enables successful learning. Likely, it is also the mechanism by which recovery after CNS lesioning is possible. The chapter gives an overview of the phenomena that constitute plasticity and the cellular events leading to them. Evidence for neural plasticity in different regions of the brain and in the spinal cord is summarized in the contexts of learning, recovery, and rehabilitation therapy.