Historical development and contemporary use of neuromodulation in human spinal cord injury

Role of Epidural Electrode Stimulation in Three Patients with Incomplete AIS D Spinal Cord Injury

Background/Objectives: To determine whether epidural electrical stimulation (EES) improves sensory recovery and walking function in patients with chronic spinal cord injury (SCI) with a grade on the American Spinal Cord Injury Association impairment scale (AIS) of C or D at the cervical level. Methods: Three individuals with cervical-level chronic AIS D SCI were enrolled in the study. The mean injury duration and age were 4.8 ± 4.5 (range: 1.5-10) and 56.7 ± 9 years, respectively. The participants received personalized electrical stimulation for 36 weeks and were evaluated for their SCI characteristics, the result of an AIS assessment according to the lower extremity sensorimotor scale, their muscle activity, and preoperative walking ability parameters, initially as well as at weeks 8 and 36 of the EES intervention. Results: Participants receiving EES significantly increased the muscle activity in most lower limb muscles. Regarding the AIS assessment of the lower extremities, one participant fully regained a light touch sensation, while two fully recovered their pinprick sensation (AIS sensory scores increased from 14 to 28). One participant achieved a full motor score, whereas the others' scores increased by 19 and 7 points. Compared with preoperative gait parameters, two participants showed improvements in their walking speed and cadence. Walking symmetry, an important parameter for assessing walking function, improved by 68.7%, 88%, and 77% in the three participants, significantly improving the symmetry index (p = 0.003). Conclusions: Thus, EES may be an effective strategy for sensory impairment recovery, as well as muscular activity and strength improvement. These findings may facilitate stable walking in subjects with chronic incomplete SCI, but larger clinical trials are warranted. Clinical trial: NCT05433064.

Effects of Noninvasive or Minimally Invasive Neuromodulation Techniques on Neurogenic Lower Urinary Tract Dysfunction After Spinal Cord Injury: A Network Meta-analysis

OBJECTIVE

To assess the available evidence of noninvasive or minimally invasive neuromodulation therapies in improving urodynamic outcomes, voiding diaries, and quality of life in patients with neurogenic lower urinary tract dysfunction (NLUTD) after spinal cord injury (SCI).

DATA SOURCES

A comprehensive search of 10 databases from inception until August 30, 2023, was conducted.

STUDY SELECTION

Randomized controlled trials (RCTs) assessing the effects of conventional treatment (CT) and CT combined with sham stimulation, transcranial magnetic stimulation (TMS), sacral nerve magnetic stimulation (SNMS), TMS+SNMS, sacral pulsed electromagnetic field therapy (SPEMFT), sacral transcutaneous electrical nerve stimulation (STENS), sacral dermatomal transcutaneous electrical nerve stimulation, bladder & STENS, transcutaneous tibial nerve stimulation (TTNS), transcutaneous electrical acupoint stimulation, pelvic floor electrical stimulation, or pelvic floor biofeedback therapy on postvoid residual volume (PVR), maximum cystometric capacity (MCC), number of voids per 24 hours (V24), mean urine volume per micturition, (MUV), maximum urinary flow rate (Qmax), maximum detrusor pressure (MDP), maximum voiding volume, number of leakages per 24 hours (L24), lower urinary tract symptoms score, and SCI-quality of life (SCI-QoL) score in patients with NLUTD after SCI were included.

DATA EXTRACTION

Two researchers independently extracted data on study characteristics and outcomes following the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. The Cochrane risk of bias tool (2.0) was used to assess the quality of RCTs.

DATA SYNTHESIS

Fifty-two RCTs with 2884 participants were included. CT+TMS was able to remarkably decrease PVR (mean difference [MD], -132.14; 95% confidence interval [CI], -230.97 to -33.31) and increase MUV (MD, 147.79; 95% CI, 64.51-231.06). CT+SNMS ranked high in improving V24 (MD, 2.76; 95% CI, 1.26-4.25) and reducing L24 (MD, -2.73; 95% CI, -4.46 to -1.01); CT+TMS+SNMS maximized the reduction of SCI-QoL scores (MD, -1.52; 95% CI, -2.97 to -0.25) and ranked second in both reducing PVR and improving MCC; CT+SPEMFT had a significant advantage in improving MCC (MD, 83.31; 95% CI, 39.73-126.88) and increasing Qmax (MD, 5.91; 95% CI, 2.99-8.84). Improvement in MDP was highly ranked by CT+TTNS (MD, 9.46; 95% CI, 2.15-16.76).

CONCLUSIONS

CT combined with magnetic stimulation therapy provided more benefits than its combination with electrical stimulation. TMS+SNMS seemed to be a promising noninvasive neuromodulation technique in managing NLUTD after SCI. High-quality RCTs should be conducted in the future to validate these findings.

Targeted Selection of Stimulation Parameters for Restoration of Motor and Autonomic Function in Individuals With Spinal Cord Injury

STUDY DESIGN

This is a report of methods and tools for selection of task and individual configurations targeted for voluntary movement, standing, stepping, blood pressure stabilization, and facilitation of bladder storage and emptying using tonic-interleaved excitation of the lumbosacral spinal cord.

OBJECTIVES

This study aimed to present strategies used for selection of stimulation parameters for various motor and autonomic functions.

CONCLUSIONS

Tonic-interleaved functionally focused neuromodulation targets a myriad of consequences from spinal cord injury with surgical implantation of the epidural electrode at a single location. This approach indicates the sophistication of the human spinal cord circuitry and its important role in the regulation of motor and autonomic functions in humans.

Updating perspectives on spinal cord function: motor coordination, timing, relational processing, and memory below the brain

Those studying neural systems within the brain have historically assumed that lower-level processes in the spinal cord act in a mechanical manner, to relay afferent signals and execute motor commands. From this view, abstracting temporal and environmental relations is the province of the brain. Here we review work conducted over the last 50 years that challenges this perspective, demonstrating that mechanisms within the spinal cord can organize coordinated behavior (stepping), induce a lasting change in how pain (nociceptive) signals are processed, abstract stimulus-stimulus (Pavlovian) and response-outcome (instrumental) relations, and infer whether stimuli occur in a random or regular manner. The mechanisms that underlie these processes depend upon signal pathways (e.g., NMDA receptor mediated plasticity) analogous to those implicated in brain-dependent learning and memory. New data show that spinal cord injury (SCI) can enable plasticity within the spinal cord by reducing the inhibitory effect of GABA. It is suggested that the signals relayed to the brain may contain information about environmental relations and that spinal cord systems can coordinate action in response to descending signals from the brain. We further suggest that the study of stimulus processing, learning, memory, and cognitive-like processing in the spinal cord can inform our views of brain function, providing an attractive model system. Most importantly, the work has revealed new avenues of treatment for those that have suffered a SCI.

Spinal Cord Injury Community Personal Opinions and Perspectives on Spinal Cord Stimulation

Background

Spinal cord stimulation (SCS) clinical trials are evaluating its efficacy and safety for motor, sensory, and autonomic recovery following spinal cord injury (SCI). The perspectives of people living with SCI are not well known and can inform the planning, delivery, and translation of SCS.

Objectives

To obtain input from people living with SCI on the top priorities for recovery, expected meaningful benefits, risk tolerance, clinical trial design, and overall interest in SCS.

Methods

Data were collected anonymously from an online survey between February and May 2020.

Results

A total of 223 respondents living with SCI completed the survey. The majority of respondents identified their gender as male (64%), were 10+ years post SCI (63%), and had a mean age of 50.8 years. Most individuals had a traumatic SCI (81%), and 45% classified themselves as having tetraplegia. Priorities for improved outcome for those with complete or incomplete tetraplegia included fine motor skills and upper body function, whereas priorities for complete or incomplete paraplegia included standing and walking, and bowel function. The meaningful benefits that are important to achieve are bowel and bladder care, less reliance on caregivers, and maintaining physical health. Perceived potential risks include further loss of function, neuropathic pain, and complications. Barriers to participation in clinical trials include inability to relocate, out-of-pocket expenses, and awareness of therapy. Respondents were more interested in transcutaneous SCS than epidural SCS (80% and 61%, respectively).

Conclusion

SCS clinical trial design, participant recruitment, and translation of the technology can be improved by better reflecting the priorities and preferences of those living with SCI identified from this study.

Beyond treatment of chronic pain: a scoping review about epidural electrical spinal cord stimulation to restore sensorimotor and autonomic function after spinal cord injury

Epidural electrical epinal cord stimulation (ESCS) is an established therapeutic option in various chronic pain conditions. In the last decade, proof-of-concept studies have demonstrated that ESCS in combination with task-oriented rehabilitative interventions can partially restore motor function and neurological recovery after spinal cord injury (SCI). In addition to the ESCS applications for improvement of upper and lower extremity function, ESCS has been investigated for treatment of autonomic dysfunction after SCI such as orthostatic hypotension. The aim of this overview is to present the background of ESCS, emerging concepts and its readiness to become a routine therapy in SCI beyond treatment of chronic pain conditions.