Supraspinal and Afferent Signaling Facilitate Spinal Sensorimotor Network Excitability After Discomplete Spinal Cord Injury: A Case Report

Abstract

In this study, we evaluated the role of residual supraspinal and afferent signaling and their convergence on the sublesional spinal network in subject diagnosed with complete paralysis (AIS-A).Methods: A combination of electrophysiologic techniques with positional changes and subject-driven reinforcement maneuvers was implemented in this study. Electrical stimulation was applied transcutaneously at the T9-L2 vertebra levels and the spinal cord motor evoked potentials (SEMP) were recorded from leg muscles. To test the influence of positional changes, the subject was placed in (i) supine, (ii) upright with partial body weight bearing and (iii) vertically suspended without body weight bearing positions.Results: Increase in amplitude of SEMP was observed during transition from supine to upright position, supporting the role of sensory input in lumbosacral network excitability. Additionally, amplitudes of SEMP were facilitated during reinforcement maneuvers, indicating a supralesional influence on sub-lesional network. After initial assessment, subject underwent rehabilitation therapy with following electrophysiological testing that reviled facilitation of SEMP. Conclusion:These results demonstrate that combination of electrophysiological techniques with positional and reinforcement maneuvers can add to the diagnostics of discomplete SCI. These findings also support an idea that integration of supraspinal and afferent information on sub-lesional circuitry plays a critical role in facilitation of spinal sensorimotor network in discomplete SCI.

Combined Supra- and Sub-Lesional Epidural Electrical Stimulation for Restoration of the Motor Functions after Spinal Cord Injury in Mini Pigs

“…This profile of trauma is known as “incomplete” [ 72 , 73 ]. The role of this residual subfunctional connectivity after SCI and mechanisms of its reactivation by electrical stimulation remains largely unknown [ 16 , 74 ]. The neural networks below and above the injury may form a translesional network, which can reorganize over time in functional neuronal structure involved in the restoration of the motor functions, such as volitional motor control with EES.…”

The Role of Supraspinal Structures for Recovery after SCI: From Motor Dysfunction to Mental Health

“…Even some subjects AIS-ASIA A can regain some steeping capabilities without using body weight support [94,95]. The fact that ES enables voluntary motor activation even in subjects classified as AIS-ASIA A, suggests that some spare descending fibers can still be activated even at chronic SCI stages after several years [95,96,101,102]. It is noteworthy to mention that in the absence of ES, the capacity to perform voluntary motor activities is somewhat limited, concluding that facilitation provided by ES should be continually administered in otherwise "dormant" spinal circuits.…”

Newly regenerated axons through a cell-containing biomaterial scaffold promote reorganization of spinal circuitry and restoration of motor functions with epidural electrical stimulation

“…Greater synaptophysin co-localization with motor neuron and interneuron in animals treated with combined therapy suggests that regenerating axons form functional connections with sub-lesional circuitry facilitating reorganization with EES-enabled training. Plasticity below the SCI has been attributed to rehabilitation 43,44 , while the quality of movement is largerly depends on descending commands and sensory feedback integration on different interneuronal populations 11,17,[45][46][47][48] . Although the numbers of rats are relatively small, the concordance of behavioral, electrophysiological and histological results convincingly demonstrate that greater synaptic reorganization on the interneurons in the presence of regenerated axons leads to improvements in polysynaptic responses, improving gait, particularly in group with combined treatment.…”

“…Recent advances in bioelectronics and tissue engineering make available novel neuromodulatory and neuroregenerative therapies, aimed to improve function after SCI [1][2][3][4][5] . Encouraging results using epidural electrical stimulation (EES) to restore motor function in humans with SCI [6][7][8] have been attributed to the presence of functionally silent fibers and the combination of EES and motor training [9][10][11] . Most of the patients diagnosed with complete loss of motor function after SCI demonstrate some degree of subfunctional connectivity, which provides the anatomical and functional basis for supraspinal control in the presence of EES 11,12 .…”

“…Encouraging results using epidural electrical stimulation (EES) to restore motor function in humans with SCI [6][7][8] have been attributed to the presence of functionally silent fibers and the combination of EES and motor training [9][10][11] . Most of the patients diagnosed with complete loss of motor function after SCI demonstrate some degree of subfunctional connectivity, which provides the anatomical and functional basis for supraspinal control in the presence of EES 11,12 . Elucidating the mechanisms of EES-enabled restoration of motor function after SCI with sub-functional connectivity is critical for optimizing combined neurostimulation and neuroregenerative therapy.…”