Peak Slope Ratio of the Recruitment Curves Compared to Muscle Evoked Potentials to Optimize Standing Configurations with Percutaneous Epidural Stimulation after Spinal Cord Injury.

Background: Percutaneous spinal cord epidural stimulation (pSCES) has effectively restored varying levels of motor control in persons with motor complete spinal cord injury (SCI). Studying and standardizing the pSCES configurations may yield specific motor improvements. Previously, reliance on the amplitude of the SCES-evoked potentials (EPs) was used to determine the correct stimulation configurations. Methods: We, hereby, retrospectively examined the effects of wide and narrow-field configurations on establishing the motor recruitment curves of motor units of three different agonist-antagonist muscle groups. Magnetic resonance imaging was also used to individualize SCI participants (n = 4) according to their lesion characteristics. The slope of the recruitment curves using a six-degree polynomial function was calculated to derive the slope ratio for the agonist-antagonist muscle groups responsible for standing. Results: Axial damage ratios of the spinal cord ranged from 0.80 to 0.92, indicating at least some level of supraspinal connectivity for all participants. Despite the close range of these ratios, standing motor performance was enhanced using different stimulation configurations in the four persons with SCI. A slope ratio of ≥1 was considered for the recommended configurations necessary to achieve standing. The retrospectively identified configurations using the supine slope ratio of the recruitment curves of the motor units agreed with that visually inspected muscle EPs amplitude of the extensor relative to the flexor muscles in two of the four participants. Two participants managed to advance the selected configurations into independent standing performance after using tonic stimulation. The other two participants required different levels of assistance to attain standing performance. Conclusions: The findings suggest that the peak slope ratio of the muscle agonists-antagonists recruitment curves may potentially identify the pSCES configurations necessary to achieve standing in persons with SCI.

A case study of percutaneous epidural stimulation to enable motor control in two men after spinal cord injury.

Two persons with chronic motor complete spinal cord injury (SCI) were implanted with percutaneous spinal cord epidural stimulation (SCES) leads to enable motor control below the injury level (NCT04782947). Through a period of temporary followed by permanent SCES implantation, spinal mapping was conducted primarily to optimize configurations enabling volitional control of movement and training of standing and stepping as a secondary outcome. In both participants, SCES enabled voluntary increased muscle activation and movement below the injury and decreased assistance during exoskeleton-assisted walking. After permanent implantation, both participants voluntarily modulated induced torques but not always in the intended directions. In one participant, percutaneous SCES enabled motor control below the injury one-day following temporary implantation as confirmed by electromyography. The same participant achieved independent standing with minimal upper extremity self-balance assistance, independent stepping in parallel bars and overground ambulation with a walker. SCES via percutaneous leads holds promise for enhancing rehabilitation and enabling motor functions for people with SCI.

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.

Epidural stimulation with locomotor training ameliorates unstable blood pressure after tetraplegia. A case report.

A male with C7 complete tetraplegia participated in 14 weeks of body weight supported treadmill training (BWSTT) combined with spinal cord epidural stimulation (SCES), 4 weeks of no intervention, and two more weeks of BWSTT + SCES. The participant presented with unstable resting seated blood pressure (BP; 131/66 mmHg). After retrospective analysis, resting systolic BP decreased and diastolic BP increased, yielding a safe mean arterial BP. There was a fivefold increase in BWSTT bouts per session, and percentage of body weight support decreased to 69%. BWSTT + SCES safely and effectively regulated resting BP and mitigated symptoms of orthostatic intolerance. These effects were not maintained after 4 weeks without training.

Peripheral nerve stimulation for the management of acute and subacute post-amputation pain: a randomized, controlled feasibility trial.

Introduction & aim: Temporary (60-day) percutaneous peripheral nerve stimulation (PNS) has demonstrated effectiveness for the treatment of chronic post-amputation pain, and this pilot study aims to evaluate the feasibility of temporary percutaneous PNS for the treatment of acute post-amputation pain. Patients & methods: Sixteen veterans undergoing lower extremity amputation received PNS and standard medical therapy or standard medical therapy alone. Results: The PNS group reported greater reductions in average phantom limb pain, residual limb pain and daily opioid consumption, and there were fewer participants taking opioids through 3 months post-amputation. Conclusion: This pilot study suggests that PNS is feasible in the acute postoperative period following lower limb amputation and may provide a non-pharmacologic analgesic therapy that lowers pain scores and reduces opioid consumption, and thus warrants further investigation.

A small study was done to evaluate placing a wire lead near a nerve to electrically stimulate it for 60 days after a leg amputation surgery to see if it helps reduce pain. The study looked at 16 veterans who had an amputation to their leg. These patients were divided into either a group that received nerve stimulation plus normal pain control medications or a group that just received pain medications. The group that received nerve stimulation had less pain in the remaining leg and less phantom pain (pain in the missing leg). They also required fewer narcotic medications. The study suggested that nerve stimulation may provide an effective way to manage pain after amputation and reduce the use of pain medications. Clinical Trial Registration Number: NCT03484429.

The feasibility of using exoskeletal-assisted walking with epidural stimulation: a case report study.

Spinal cord epidural stimulation (SCES) exhibits a rehabilitation potential of restoring locomotion in individuals with spinal cord injury (SCI). However, this is linked to an intensive rehabilitation locomotion approach, which is impractical to apply among a large clinical SCI population. We, hereby, propose a rehabilitation approach of using SCES to enhance motor control during exoskeletal-assisted walking (EAW). After 24 sessions (12 weeks) of EAW swing assistance decreased from 100% to 35% in a person with C7 complete SCI. This was accompanied by 573 unassisted steps (50% of the total number of steps). Electromyographic pattern improved during EAW, reflecting the subject's ability to rhythmically activate paralyzed muscles. Rate perceived exertion increased during EAW with SCES compared to stepping without SCES. These preliminary findings suggest that using SCES with EAW may be a feasible rehabilitation approach for persons with SCI.

Percutaneous Peripheral Nerve Stimulation for the Treatment of Chronic Pain Following Amputation.

INTRODUCTION: Chronic pain and reduced function are significant problems for Military Service members and Veterans following amputation. Peripheral nerve stimulation (PNS) is a promising therapy, but PNS systems have traditionally been limited by invasiveness and complications. Recently, a novel percutaneous PNS system was developed to reduce the risk of complications and enable delivery of stimulation without surgery. MATERIALS AND METHODS: Percutaneous PNS was evaluated to determine if stimulation provides relief from residual and phantom limb pain following lower-extremity amputation. PNS leads were implanted percutaneously to deliver stimulation to the femoral and/or sciatic nerves. Patients received stimulation for up to 60 days followed by withdrawal of the leads. RESULTS: A review of recent studies and clinical reports found that a majority of patients (18/24, 75%) reported substantial (≥50%) clinically relevant relief of chronic post-amputation pain following up to 60 days of percutaneous PNS. Reductions in pain were frequently associated with reductions in disability and pain interference. CONCLUSIONS: Percutaneous PNS can durably reduce pain, thereby enabling improvements in quality of life, function, and rehabilitation in individuals with residual or phantom limb pain following amputation. Percutaneous PNS may have additional benefit for Military Service members and Veterans with post-surgical or post-traumatic pain.

Organization of sensory input to the nociceptive-specific cutaneous trunk muscle reflex in rat, an effective experimental system for examining nociception and plasticity.

Detailed characterization of neural circuitries furthers our understanding of how nervous systems perform specific functions and allows the use of those systems to test hypotheses. We have characterized the sensory input to the cutaneous trunk muscle (CTM; also cutaneus trunci [rat] or cutaneus maximus [mouse]) reflex (CTMR), which manifests as a puckering of the dorsal thoracolumbar skin and is selectively driven by noxious stimuli. CTM electromyography and neurogram recordings in naïve rats revealed that CTMR responses were elicited by natural stimuli and electrical stimulation of all segments from C4 to L6, a much greater extent of segmental drive to the CTMR than previously described. Stimulation of some subcutaneous paraspinal tissue can also elicit this reflex. Using a selective neurotoxin, we also demonstrate differential drive of the CTMR by trkA-expressing and nonexpressing small-diameter afferents. These observations highlight aspects of the organization of the CTMR system that make it attractive for studies of nociception and anesthesiology and plasticity of primary afferents, motoneurons, and the propriospinal system. We use the CTMR system to demonstrate qualitatively and quantitatively that experimental pharmacological treatments can be compared with controls applied either to the contralateral side or to another segment, with the remaining segments providing controls for systemic or other treatment effects. These data indicate the potential for using the CTMR system as both an invasive and a noninvasive quantitative assessment tool providing improved statistical power and reduced animal use.

A report of 3 soldiers returned to full duty after lumbar radiofrequency facet denervation in a theater of war.

OBJECTIVE: To provide the advanced interventional procedure of zygapophysial joint neurotomy to soldiers meeting the diagnostic criteria in a combat environment and thus reduce medical evacuations of soldiers from a theater of war. DESIGN: Retrospective chart review was performed on three consecutive soldiers who received neuroablation of the lumbar ZP joint. Patients received single MBB with 1 cc of 1% lidocaine at the b/l L3-L5 levels considered diagnostic if >50% analgesia was achieved concordant with duration of anesthetic. SETTING: All procedures were co-performed by the two authors at the Ibn Sina hospital in Baghdad, Iraq over a 3-month period. PATIENTS: Three consecutive patients with >50% pain relief from diagnostic medial branch blocks were treated with radiofrequency ablation of the bilateral L3-L4 medial branch nerves and L5 posterior primary ramus. INTERVENTIONS: Sensory test stimulation at 50 Hz and motor stimulation at 2 Hz were performed at each level. The nerves were then lesioned at 80° Centigrade for 90 seconds after injection of lidocaine and methylprednisolone. OUTCOME MEASURES: Procedure was considered successful if patients were able to wear body armour without significant discomfort (at least 1 hour/day). RESULTS AND CONCLUSIONS: Medical evacuation from Iraq was prevented and all soldiers returned to rigorous combat duties including the wearing of body armour daily. We believe to be the first to report on the use of RF nerve ablation in a war time setting and with this functional outcome.