Neurophysiology of epidurally evoked spinal cord reflexes in clinically motor-complete posttraumatic spinal cord injury.

Increased use of epidural Spinal Cord Stimulation (eSCS) for the rehabilitation of spinal cord injury (SCI) has highlighted the need for a greater understanding of the properties of reflex circuits in the isolated spinal cord, particularly in response to repetitive stimulation. Here, we investigate the frequency-dependence of modulation of short- and long-latency EMG responses of lower limb muscles in patients with SCI at rest. Single stimuli could evoke short-latency responses as well as long-latency (likely polysynaptic) responses.

Spinal cord injuries, human neuropathology and neurophysiology.

A correlative approach to human spinal cord injuries (SCI) through the combination of neuropathology and neurophysiology provides a much better understanding of the condition than with either alone. Among the benefits so derived is the wide range of interventions applicable to the restorative neurology (RN) of SCI so that the neurological status of the SCI patient is thereby much improved. The neurophysiological and neuropathological elements underlying these advances are described.

Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017).

Cell therapy has been shown to be a key clinical therapeutic option for central nervous system diseases or damage. Standardization of clinical cell therapy procedures is an important task for professional associations devoted to cell therapy. The Chinese Branch of the International Association of Neurorestoratology (IANR) completed the first set of guidelines governing the clinical application of neurorestoration in 2011.

Motor Control of Human Spinal Cord Disconnected from the Brain and Under External Movement.

Motor control after spinal cord injury is strongly depending on residual ascending and descending pathways across the lesion. The individually altered neurophysiology is in general based on still intact sublesional control loops with afferent sensory inputs linked via interneuron networks to efferent motor outputs. Partial or total loss of translesional control inputs reduces and alters the ability to perform voluntary movements and results in motor incomplete (residual voluntary control of movement functions) or motor complete (no residual voluntary control) spinal cord injury classification.

Epidural and transcutaneous spinal electrical stimulation for restoration of movement after incomplete and complete spinal cord injury.

Purpose Of Review: The Purpose of this review is to outline and explain the therapeutic use of electrical spinal cord stimulation (SCS) for modification of spinal motor output. Central functional stimulation provides afferent input to posterior root neurons and is applied to improve volitional movements, posture and their endurance, control spasticity, and improve bladder function or perfusion in the lower limbs. Clinical accomplishments strongly depend on each individual's physiological state and specific methodical adaptation to that physiological state.

Neurocontrol of Movement in Humans With Spinal Cord Injury.

In this review of neurocontrol of movement after spinal cord injury, we discuss neurophysiological evidences of conducting and processing mechanisms of the spinal cord. We illustrate that external afferent inputs to the spinal cord below the level of the lesion can modify, initiate, and maintain execution of movement in absence or partial presence of brain motor control after chronic spinal cord injury. We review significant differences between spinal reflex activity elicited by single and repetitive stimulation.

Outline of restorative neurology: definition, clinical practice, assessment, intervention.

Rather than focusing on the deficits and lost function caused by upper motor neuron lesions or disorders, it is more advantageous to elucidate, in each individual, the specific neural functions that remain available, and then, to build upon them by designing a treatment protocol to optimize their effectiveness and thus improve recovery. The practice of Restorative Neurology is based on detailed assessment of the individual patient, the use of neurophysiological methods to elucidate and characterize subclinical function and the application of interventions that modify neural activity to improve clinical function.

Stimulation of the human lumbar spinal cord with implanted and surface electrodes: a computer simulation study.

Human lumbar spinal cord networks controlling stepping and standing can be activated through posterior root stimulation using implanted electrodes. A new stimulation method utilizing surface electrodes has been shown to excite lumbar posterior root fibers similarly as with implants, an unexpected finding considering the distance to these target neurons. In the present study we apply computer modeling to compare the depolarization of posterior root fibers by both stimulation techniques.

Modification of reflex responses to lumbar posterior root stimulation by motor tasks in healthy subjects.

Dynamic task-dependent regulation of reflexes controlled by the central nervous system plays an integral part in neurocontrol of locomotion. Such modifications of sensory-motor transmission can be studied by conditioning a test reflex with specific motor tasks. To elicit short-latency test reflexes, we applied a novel transcutaneous spinal cord stimulation technique that depolarizes large-diameter posterior root afferents.

Clinical practice of functional electrical stimulation: from "Yesterday" to "Today".

Functional electrical stimulation (FES) is an accepted treatment method for paresis or paralysis after spinal cord and head injury as well as stroke and other neurological upper motor neuron disorders. At the beginning, FES worked like an electrophysiological brace for the correction of drop foot of patients after a stroke. When analyzing early accomplishments, it becomes evident that FES was influenced rather by technological and biomedical engineering development than by contemporary knowledge on neurocontrol of movement in individuals with upper motor neuron paralysis.

Posterior root-muscle reflexes elicited by transcutaneous stimulation of the human lumbosacral cord.

Continuous epidural stimulation of lumbar posterior root afferents can modify the activity of lumbar cord networks and motoneurons, resulting in suppression of spasticity or elicitation of locomotor-like movements in spinal cord-injured people. The aim of the present study was to demonstrate that posterior root afferents can also be depolarized by transcutaneous stimulation with moderate stimulus intensities. In healthy subjects, single stimuli applied through surface electrodes placed over the T11-T12 vertebrae with a mean intensity of 28.

Motor control in the human spinal cord.

Features of the human spinal cord motor control are described using two spinal cord injury models: (i) the spinal cord completely separated from brain motor structures by accidental injury; (ii) the spinal cord receiving reduced and altered supraspinal input due to an incomplete lesion. Systematic studies using surface electrode polyelectromyography were carried out to assess skeletal muscle reflex responses to single and repetitve stimulation in a large number of subjects. In complete spinal cord injured subjects the functional integrity of three different neuronal circuits below the lesion level is demonstrated: first, simple mono- and oligosynaptic reflex arcs and polysynaptic pathways; second, propriospinal interneuron system with their cell in the gray matter and the axons in the white matter of the spinal cord conducting activity between different spinal cord segments; and third, internuncial gray matter neurons with short axons and dense neuron contact within the spinal gray matter.

Frequency-dependent selection of alternative spinal pathways with common periodic sensory input.

Electrical stimulation of the lumbar cord at distinct frequency ranges has been shown to evoke either rhythmical, step-like movements (25-50 Hz) or a sustained extension (5-15 Hz) of the paralysed lower limbs in complete spinal cord injured subjects. Frequency-dependent activation of previously "silent" spinal pathways was suggested to contribute to the differential responsiveness to distinct neuronal "codes" and the modifications in the electromyographic recordings during the actual implementation of the evoked motor tasks. In the present study we examine this suggestion by means of a simplified biology-based neuronal network.

Clinical elements for the neuromuscular stimulation and functional electrical stimulation protocols in the practice of neurorehabilitation.

The physicians and their multidisciplinary teams involved in the clinical practice of neurological rehabilitation have more and more opportunities to apply neuromuscular stimulation (NMS) and functional electrical stimulation (FES) of peripheral nerves as a part of their daily practice. In this article, we outline clinical protocols of NMS and FES in the following clinical conditions of upper motor neuron dysfunction: to prevent consequences of disuse of the neuromuscular system of the upper motor neuron, to facilitate recovery processes of impaired upper motor neuron functions due to acute and/or subacute neurological conditions, to maintain or enhance the trophic state of the muscle, to modify altered control of muscle tone, to modify altered patterns of automatic and volitional functional movements, to enhance functional movement of the single joint muscle group within intact functional multijoint movement, and to modify altered neurocontrol of posture, locomotion, and skillful movements. We emphasize the importance of understanding the motor control alteration while developing clinical protocols and defining the goals.

Central dysesthesia syndrome in spinal cord injury patients.

We have described 13 spinal cord injury patients with a complaint of diffuse, ongoing dysesthesias below the level of the lesion, which are burning in quality, and usually functionally limiting. Quantitative sensory and neurophysiological testing revealed relative preservation of the dorsal column functions in comparison to absence of spinothalamic system mediated functions. On the basis of these findings, we are speculating that such an imbalance between the spinothalamic and dorsal column systems is the main underlying mechanism of dysesthesias as a central nervous system misinterpretation of residual peripheral input.