Exercise-Induced Alterations in Sympathetic-Somatomotor Coupling in Incomplete Spinal Cord Injury

Effects of percutaneously-implanted epidural stimulation on cardiovascular autonomic function and spasticity after complete spinal cord injury: A case report

Importance

There is a revived interest to explore spinal cord epidural stimulation (SCES) to improve physical function after spinal cord injury (SCI). This case report highlights the potential of eliciting multiple functional improvements with a single SCES configuration, a strategy which could improve clinical translation.

Objective

To determine whether SCES intended to facilitate walking also acutely yields benefits in cardiovascular autonomic regulation and spasticity.

Design

Case report from data collected at two timepoints 15 weeks apart from March to June 2022 as part of a larger clinical trial.

Setting

Research lab at Hunter Holmes McGuire VA Medical Center.

Participant

27-year-old male, 7 years post a C8 motor complete spinal cord injury.

Intervention

A SCES configuration intended to enhance exoskeleton-assisted walking training applied for autonomic and spasticity management.

Main outcomes and measures

The primary outcome was cardiovascular autonomic response to a 45-degree head-up-tilt test. Systolic blood pressure (SBP), heart rate (HR), and absolute power of the low-frequency (LF) and high-frequency (HF) components of a heart-rate variability analysis were collected in supine and tilt with and without the presence of SCES. Right knee flexor and knee extensor spasticity was assessed via isokinetic dynamometry with and without SCES.

Results

At both assessments with SCES off, transitioning from supine to tilt decreased SBP (assessment one: 101.8 to 70 mmHg; assessment two: 98.9 to 66.4 mmHg). At assessment one, SCES on in supine (3 mA) increased SBP (average 117 mmHg); in tilt, 5 mA stabilized SBP near baseline values (average 111.5 mmHg). At assessment two, SCES on in supine (3 mA) increased SBP (average 140 mmHg in minute one); decreasing amplitude to 2 mA decreased SBP (average 119 mmHg in minute five). In tilt, 3 mA stabilized SBP near baseline values (average 93.2 mmHg). Torque-time integrals at the right knee were reduced at all angular velocities for knee flexors (range: -1.9 to -7.8%) and knee extensors (range: -1 to -11.4%).

Conclusions and relevance

These results demonstrate that SCES intended to facilitate walking may also enhance cardiovascular autonomic control and attenuate spasticity. Using one configuration to enhance multiple functions after SCI may accelerate clinical translation.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/, identifier NCT04782947.

Exercise-Induced Plasticity in Signaling Pathways Involved in Motor Recovery after Spinal Cord Injury

Spinal cord injury (SCI) leads to numerous chronic and debilitating functional deficits that greatly affect quality of life. While many pharmacological interventions have been explored, the current unsurpassed therapy for most SCI sequalae is exercise. Exercise has an expansive influence on peripheral health and function, and by activating the relevant neural pathways, exercise also ameliorates numerous disorders of the central nervous system (CNS). While the exact mechanisms by which this occurs are still being delineated, major strides have been made in the past decade to understand the molecular underpinnings of this essential treatment. Exercise rapidly and prominently affects dendritic sprouting, synaptic connections, neurotransmitter production and regulation, and ionic homeostasis, with recent literature implicating an exercise-induced increase in neurotrophins as the cornerstone that binds many of these effects together. The field encompasses vast complexity, and as the data accumulate, disentangling these molecular pathways and how they interact will facilitate the optimization of intervention strategies and improve quality of life for individuals affected by SCI. This review describes the known molecular effects of exercise and how they alter the CNS to pacify the injury environment, increase neuronal survival and regeneration, restore normal neural excitability, create new functional circuits, and ultimately improve motor function following SCI.

Improvements in Bladder Function Following Activity-Based Recovery Training With Epidural Stimulation After Chronic Spinal Cord Injury

Spinal cord injury (SCI) results in profound neurologic impairment with widespread deficits in sensorimotor and autonomic systems. Voluntary and autonomic control of bladder function is disrupted resulting in possible detrusor overactivity, low compliance, and uncoordinated bladder and external urethral sphincter contractions impairing storage and/or voiding. Conservative treatments managing neurogenic bladder post-injury, such as oral pharmacotherapy and catheterization, are important components of urological surveillance and clinical care. However, as urinary complications continue to impact long-term morbidity in this population, additional therapeutic and rehabilitative approaches are needed that aim to improve function by targeting the recovery of underlying impairments. Several human and animal studies, including our previously published reports, have documented gains in bladder function due to activity-based recovery strategies, such as locomotor training. Furthermore, epidural stimulation of the spinal cord (scES) combined with intense activity-based recovery training has been shown to produce volitional lower extremity movement, standing, as well as improve the regulation of cardiovascular function. In our center, several participants anecdotally reported improvements in bladder function as a result of training with epidural stimulation configured for motor systems. Thus, in this study, the effects of activity-based recovery training in combination with scES were tested on bladder function, resulting in improvements in overall bladder storage parameters relative to a control cohort (no intervention). However, elevated blood pressure elicited during bladder distention, characteristic of autonomic dysreflexia, was not attenuated with training. We then examined, in a separate, large cross-sectional cohort, the interaction between detrusor pressure and blood pressure at maximum capacity, and found that the functional relationship between urinary bladder distention and blood pressure regulation is disrupted. Regardless of one’s bladder emptying method (indwelling suprapubic catheter vs. intermittent catheterization), autonomic instability can play a critical role in the ability to improve bladder storage, with SCI enhancing the vesico-vascular reflex. These results support the role of intersystem stimulation, integrating scES for both bladder and cardiovascular function to further improve bladder storage.

Effect of chronic spinal cord injury's severity on sperm parameters in rat: correlation with locomotion deficits

OBJECTIVES

Infertility is one of the major concerns for male patients following spinal cord injury (SCI). Although the severity of the injury has a large impact on extent of infertility, the effect of exact injury extent (with specific affected spinal tracts) on fertility is not studied yet.

MATERIALS AND METHODS

In the present study, sperm parameters, locomotion scores, and hormonal changes were evaluated following dorsal one third SCI (1/3 SCI), dorsal two third SCI (2/3 SCI), and complete spinal cord transection (TX) at T8 spinal level in male rats.

RESULTS

Sperm count decreased significantly following 1/3 SCI and Tx compered to normal (control and sham). In addition, sperm count decreased significantly in Tx compared to 1/3 SCI and 2/3 SCI. Concerning sperm motility, although, percentage of motile sperms decreased significantly in Tx group in comparison to all other groups, the percentage of rapid progressive motile sperms (RPM) decreased significantly in all SCI groups compared to normal. Meanwhile, locomotion score (BBB-score) showed a significant progressive decrease following SCI compared to normal or within SCI groups. However, there was no significant changes in the serum hormonal and seminal fructose concentrations following SCI compared to normal.

CONCLUSIONS

These results show that understanding the extent of SCI, the affected spinal tracts, and the resultant locomotion deficits may help to predict the deficits in sperm parameters and hence fertility potentials.