Neuromodulation of the lumbar spinal locomotor circuit

Effects of end-effector robot-assisted gait training on gait ability, muscle strength, and balance in patients with spinal cord injury

BACKGROUND

There is no randomized controlled study about the effects of end-effector robot-assisted gait training (RAGT) in patients with spinal cord injury (SCI).

OBJECTIVE

To examine the effects of end-effector RAGT on gait and balance abilities in SCI.

METHODS

Thirty-one patients were randomly assigned to the RAGT (Morning Walk®, Curexo, Seoul, South Korea) or conventional therapy (CT) group. Patients were assessed using the 10-meter walk test (10MWT), 6-minute walk test (6mWT), lower extremity motor score (LEMS) and proprioception, Berg Balance Scale (BBS), Walking Index for Spinal Cord Injury-II (WISCI-II), and mobility category of Spinal Cord Independence Measure-III.

RESULTS

All clinical outcome measures significantly improved in both groups. The BBS and WISCI-II were significantly improved in the RAGT group compared to the CT group. In the RAGT group, pre-LEMS and pre-WISCI-II of the 10MWT improved group and pre-BBS of the 6mWT improved group were higher than those of the 10MWT non-improved and 6mWT non-improved group, respectively.

CONCLUSION

End-effector RAGT and CT in patients with incomplete SCI could lead to improvements in gait ability, lower extremity muscle strength, balance, proprioception, and mobility. Additionally, end-effector RAGT could improve balance and gait abilities substantially better than CT.

Body weight-supported gait training for patients with spinal cord injury: a network meta-analysis of randomised controlled trials

Different body weight-supported gait-training strategies are available for improving ambulation in individuals with spinal cord injury (SCI). These include body weight-supported overground training (BWSOGT), body weight-supported treadmill training (BWSTT), and robot-assisted gait training (RAGT). We conducted a network meta-analysis of randomised controlled trials (RCTs) to assess the effect and priority of each training protocol. We searched the PubMed, Cochrane Library, Scopus, and Embase databases from inception to 6 August 2022. The eligibility criteria were as follows: (1) being RCTs, (2) recruiting participants with SCI diagnosis and requiring gait training, (3) comparing different body weight-supported gait training strategies, and (4) involving ambulatory assessments. We conducted a network meta-analysis to compare different training strategies using the standard mean difference and its 95% credible interval. To rank the efficacy of training strategies, we used the P score as an indicator. Inconsistency in network meta-analysis was evaluated using loop-specific heterogeneity. We included 15 RCTs in this analysis. RAGT was had significantly more favourable performance than had the control intervention. The ranking probabilities indicated that the most effective approach was RAGT, followed by BWSOGT, BWSTT, and the control intervention. No significant inconsistency was noted between the results of the direct and indirect comparisons.

Finding the Way to Improve Motor Recovery of Patients with Spinal Cord Lesions: A Case-Control Pilot Study on a Novel Neuromodulation Approach

Robot-assisted rehabilitation (RAR) and non-invasive brain stimulation (NIBS) are interventions that, both individually and combined, can significantly enhance motor performance after spinal cord injury (SCI). We sought to determine whether repetitive transcranial magnetic stimulation (rTMS) combined with active transvertebral direct current stimulation (tvDCS) (namely, NIBS) in association with RAR (RAR + NIBS) improves lower extremity motor function more than RAR alone in subjects with motor incomplete SCI (iSCI). Fifteen adults with iSCI received one daily session of RAR+NIBS in the early afternoon, six sessions weekly, for eight consecutive weeks. Outcome measures included the 6 min walk test (6MWT), the 10 m walk test (10MWT), the timed up and go (TUG) to test mobility and balance, the Walking Index for Spinal Cord Injury (WISCI II), the Functional Independence Measure-Locomotion (FIM-L), the manual muscle testing for lower extremity motor score (LEMS), the modified Ashworth scale for lower limbs (MAS), and the visual analog scale (VAS) for pain. The data of these subjects were compared with those of 20 individuals matched for clinical and demographic features who previously received the same amount or RAR without NIBS (RAR - NIBS). All patients completed the trial, and none reported any side effects either during or following the training. The 10MWT improved in both groups, but the increase was significantly greater following RAR + NIBS than RAR - NIBS. The same occurred for the FIM-L, LEMS, and WISCI II. No significant differences were appreciable concerning the 6MWT and TUG. Conversely, RAR - NIBS outperformed RAR + NIBS regarding the MAS and VAS. Pairing tvDCS with rTMS during RAR can improve lower extremity motor function more than RAR alone can do. Future research with a larger sample size is recommended to determine longer-term effects on motor function and activities of daily living.

A Controlled Clinical Study of Intensive Neurorehabilitation in Post-Surgical Dogs with Severe Acute Intervertebral Disc Extrusion

Simple Summary

This study explores the potential intensive neurorehabilitation plasticity effects in post-surgical paraplegic dogs with severe acute intervertebral disc extrusion aiming to achieve ambulatory status. The intensive neurorehabilitation protocol translated in 99.4% (167/168) of recovery in deep pain perception-positive dogs and 58.5% (55/94) in deep pain perception-negative dogs. There was 37.3% (22/59) spinal reflex locomotion, obtained within a maximum period of 3 months. Thus, intensive neurorehabilitation may be a useful approach for this population of dogs, avoiding future euthanasia and promoting an estimated time window of 3 months to recover.

Abstract

This retrospective controlled clinical study aimed to verify if intensive neurorehabilitation (INR) could improve ambulation faster than spontaneous recovery or conventional physiotherapy and provide a possible therapeutic approach in post-surgical paraplegic deep pain perception-positive (DPP⁺) (with absent/decreased flexor reflex) and DPP-negative (DDP⁻) dogs, with acute intervertebral disc extrusion. A large cohort of T10-L3 Spinal Cord Injury (SCI) dogs (n = 367) were divided into a study group (SG) (n = 262) and a control group (CG) (n = 105). The SG was based on prospective clinical cases, and the CG was created by retrospective medical records. All SG dogs performed an INR protocol by the hospitalization regime based on locomotor training, electrical stimulation, and, for DPP⁻, a combination with pharmacological management. All were monitored throughout the process, and measuring the outcome for DPP⁺ was performed by OFS and, for the DPP⁻, by the new Functional Neurorehabilitation Scale (FNRS-DPP⁻). In the SG, DPP⁺ dogs had an ambulation rate of 99.4% (n = 167) and, in DPP⁻, of 58.5% (n = 55). Moreover, in DPP⁺, there was a strong statistically significant difference between groups regarding ambulation (p < 0.001). The same significant difference was verified in the DPP^– dogs (p = 0.007). Furthermore, a tendency toward a significant statistical difference (p = 0.058) regarding DPP recovery was demonstrated between groups. Of the 59 dogs that did not recover DPP, 22 dogs achieved spinal reflex locomotion (SRL), 37.2% within a maximum of 3 months. The progressive myelomalacia cases were 14.9% (14/94). Therefore, although it is difficult to assess the contribution of INR for recovery, the results suggested that ambulation success may be improved, mainly regarding time.

Does Differential Receptor Distribution Underlie Variable Responses to a Neuropeptide in the Lobster Cardiac System?

Central pattern generators produce rhythmic behaviors independently of sensory input; however, their outputs can be modulated by neuropeptides, thereby allowing for functional flexibility. We investigated the effects of C-type allatostatins (AST-C) on the cardiac ganglion (CG), which is the central pattern generator that controls the heart of the American lobster, Homarus americanus, to identify the biological mechanism underlying the significant variability in individual responses to AST-C. We proposed that the presence of multiple receptors, and thus differential receptor distribution, was at least partly responsible for this observed variability. Using transcriptome mining and PCR-based cloning, we identified four AST-C receptors (ASTCRs) in the CG; we then characterized their cellular localization, binding potential, and functional activation. Only two of the four receptors, ASTCR1 and ASTCR2, were fully functional GPCRs that targeted to the cell surface and were activated by AST-C peptides in our insect cell expression system. All four, however, were amplified from CG cDNAs. Following the confirmation of ASTCR expression, we used physiological and bioinformatic techniques to correlate receptor expression with cardiac responses to AST-C across individuals. Expression of ASTCR1 in the CG showed a negative correlation with increasing contraction amplitude in response to AST-C perfusion through the lobster heart, suggesting that the differential expression of ASTCRs within the CG is partly responsible for the specific physiological response to AST-C exhibited by a given individual lobster.

Ambulation in Dogs With Absent Pain Perception After Acute Thoracolumbar Spinal Cord Injury

Acute thoracolumbar spinal cord injury (SCI) is common in dogs frequently secondary to intervertebral disc herniation. Following severe injury, some dogs never regain sensory function to the pelvic limbs or tail and are designated chronically "deep pain negative." Despite this, a subset of these dogs develop spontaneous motor recovery over time including some that recover sufficient function in their pelvic limbs to walk independently without assistance or weight support. This type of ambulation is commonly known as "spinal walking" and can take up to a year or more to develop. This review provides a comparative overview of locomotion and explores the physiology of locomotor recovery after severe SCI in dogs. We discuss the mechanisms by which post-injury plasticity and coordination between circuitry contained within the spinal cord, peripheral sensory feedback, and residual or recovered supraspinal connections might combine to underpin spinal walking. The clinical characteristics of spinal walking are outlined including what is known about the role of patient or injury features such as lesion location, timeframe post-injury, body size, and spasticity. The relationship between the emergence of spinal walking and electrodiagnostic and magnetic resonance imaging findings are also discussed. Finally, we review possible ways to predict or facilitate recovery of walking in chronically deep pain negative dogs. Improved understanding of the mechanisms of gait generation and plasticity of the surviving tissue after injury might pave the way for further treatment options and enhanced outcomes in severely injured dogs.

Early term effects of robotic assisted gait training on ambulation and functional capacity in patients with spinal cord injury

Background/aim

The aim of the study was to determine the effects of robotic-assisted gait training on ambulation and functional capacity in patients with spinal cord injury.

Materials and methods

In total, 88 patients were included and were randomly divided into two groups. The first group underwent 16 sessions of robotic therapy training for 8 weeks and conventional therapy for 5 days a week. The second group underwent conventional treatment. The Walking Index for Spinal Cord Injury II was used to evaluate functional ambulation, and the functional independence measure score was used to assess patients’ functional independence levels in a blind manner.

Results

A significant improvement was observed in both groups according to Walking Index for Spinal Cord Injury II and functional independence measure scores (P < 0.001). However, a significantly higher improvement according to the Walking Index for Spinal Cord Injury II (P = 0.011) and functional independence measure scores (P = 0.022) was seen in the robotic group than in the control group.

Conclusions

Robotic-assisted gait training combined with conventional therapy was found to be superior to the conventional therapy in terms of gait function and level of disability.

New perspectives on the mechanisms establishing the dorsal-ventral axis of the spinal cord

Distinct classes of neurons arise at different positions along the dorsal-ventral axis of the spinal cord leading to spinal neurons being segregated along this axis according to their physiological properties and functions. Thus, the neurons associated with motor control are generally located in, or adjacent to, the ventral horn whereas the interneurons (INs) that mediate sensory activities are present within the dorsal horn. Here, we review classic and recent studies examining the developmental mechanisms that establish the dorsal-ventral axis in the embryonic spinal cord. Intriguingly, while the cellular organization of the dorsal and ventral halves of the spinal cord looks superficially similar during early development, the underlying molecular mechanisms that establish dorsal vs ventral patterning are markedly distinct. For example, the ventral spinal cord is patterned by the actions of a single growth factor, sonic hedgehog (Shh) acting as a morphogen, i.e., concentration-dependent signal. Recent studies have shed light on the mechanisms by which the spatial and temporal gradient of Shh is transduced by cells to elicit the generation of different classes of ventral INs, and motor neurons (MNs). In contrast, the dorsal spinal cord is patterned by the action of multiple factors, most notably by members of the bone morphogenetic protein (BMP) and Wnt families. While less is known about dorsal patterning, recent studies have suggested that the BMPs do not act as morphogens to specify dorsal IN identities as previously proposed, rather each BMP has signal-specific activities. Finally, we consider the promise that elucidation of these mechanisms holds for neural repair.

Report and Research Agenda of the American Geriatrics Society and National Institute on Aging Bedside-to-Bench Conference on Urinary Incontinence in Older Adults: A Translational Research Agenda for a Complex Geriatric Syndrome

The American Geriatrics Society, with support from the National Institute on Aging and other funders, held its ninth Bedside-to-Bench research conference, entitled "Urinary Incontinence in the Older Adult: A Translational Research Agenda for a Complex Geriatric Syndrome," October 16 to 18, 2016, in Bethesda, Maryland. As part of a conference series addressing three common geriatric syndromes-delirium, sleep and circadian rhythm disturbance, and urinary incontinence-the series highlighted relationships and pertinent clinical and pathophysiological commonalities between these conditions. The conference provided a forum for discussing current epidemiology, basic science, and clinical and translational research on urinary incontinence in older adults; for identifying gaps in knowledge; and for developing a research agenda to inform future investigative efforts. The conference also promoted networking involving emerging researchers and thought leaders in the field of incontinence, aging, and other fields of research, as well as National Institutes of Health program personnel.

Efficacy and safety of 9 nonoperative regimens for the treatment of spinal cord injury: A network meta-analysis

OBJECTIVE

This network meta-analysis aims to compare the efficacy and safety of 9 nonoperative regimens (placebo, pregabalin, GM-1 ganglioside, venlafaxine extended-release [venlafaxine XR], fampridine, conventional over-ground training [OT], body-weight-supported treadmill training [BWSTT], robotic-assisted gait training [RAGT] + OT and body-weight-supported over-ground training [BWSOT]) in treating spinal cord injury (SCI).

METHODS

Clinical controlled trials of 9 nonoperative regimens for SCI were retrieved in the electronic database. Traditional pairwise and Bayesian network meta-analyses were performed to compare the efficacy and safety of 9 nonoperative regimens for the treatment of SCI. Weighted mean difference (WMD), odds ratios (OR), and surface under the cumulative ranking curve (SUCRA) were calculated using the Markov Chain Monte Carlo engine Open BUGS (V.3.4.0) and R (V.3.2.1) package gemtc (V.0.6).

RESULTS

A total of 9 clinical controlled trials meeting the inclusion criteria were selected in this meta-analysis. On the aspect of efficacy, the results of pairwise meta-analysis indicated that the RAGT + OT and BWSOT might have the best efficacy in SCI patients in terms of a lower extremity motor score (LEMS) compared with conventional OT; the efficacy of RAGT + OT on SCI patients was relatively better than that of conventional OT in terms of walking index for spinal cord injury (WISCI). With the aspect of safety, the constipation rate of placebo on SCI patients was relatively higher than that of venlafaxine XR; however, with respect to headache and urinary tract infection, there was no significant difference in the safety of placebo, pregabalin, GM-1 ganglioside, venlafaxine XR, and fampridine on SCI patients. The results of SUCRA values suggested that BWSOT had the highest SUCRA value (75.25%) of LEMS; RAGT + OT had the highest SUCRA value (88.50%) of WISCI; venlafaxine XR had the highest SUCRA value (94.00%) of constipation; venlafaxine XR had the highest SUCRA value (80.00%) of headache; GM-1 ganglioside had the highest SUCRA value (87.75%) of urinary tract infection.

CONCLUSION

Our results provide evidence that the RAGT + OT and BWSOT might have the best efficacy in the treatment of SCI, and the venlafaxine XR and GM-1 ganglioside showed adequate safety for SCI.

Rehabilitation of hand function after spinal cord injury using a novel handgrip device: a pilot study

Background

Activity-based therapy (ABT) for patients with spinal cord injury (SCI), which consists of repetitive use of muscles above and below the spinal lesion, improves locomotion and arm strength. Less data has been published regarding its effects on hand function. We sought to evaluate the effects of a weekly hand-focused therapy program using a novel handgrip device on grip strength and hand function in a SCI cohort.

Methods

Patients with SCI were enrolled in a weekly program that involved activities with the MediSens (Los Angeles, CA) handgrip. These included maximum voluntary contraction (MVC) and a tracking task that required each subject to adjust his/her grip strength according to a pattern displayed on a computer screen. For the latter, performance was measured as mean absolute accuracy (MAA). The Spinal Cord Independence Measure (SCIM) was used to measure each subject’s independence prior to and after therapy.

Results

Seventeen patients completed the program with average participation duration of 21.3 weeks. The cohort included patients with American Spinal Injury Association (ASIA) Impairment Scale (AIS) A (n = 12), AIS B (n = 1), AIS C (n = 2), and AIS D (n = 2) injuries. The average MVC for the cohort increased from 4.1 N to 21.2 N over 20 weeks, but did not reach statistical significance. The average MAA for the cohort increased from 9.01 to 21.7% at the end of the study (p = .02). The cohort’s average SCIM at the end of the study was unchanged compared to baseline.

Conclusions

A weekly handgrip-based ABT program is feasible and efficacious at increasing hand task performance in subjects with SCI.

Electrical Stimulation and Motor Recovery

In recent years, several investigators have successfully regenerated axons in animal spinal cords without locomotor recovery. One explanation is that the animals were not trained to use the regenerated connections. Intensive locomotor training improves walking recovery after spinal cord injury (SCI) in people, and >90% of people with incomplete SCI recover walking with training. Although the optimal timing, duration, intensity, and type of locomotor training are still controversial, many investigators have reported beneficial effects of training on locomotor function. The mechanisms by which training improves recovery are not clear, but an attractive theory is available. In 1949, Donald Hebb proposed a famous rule that has been paraphrased as “neurons that fire together, wire together.” This rule provided a theoretical basis for a widely accepted theory that homosynaptic and heterosynaptic activity facilitate synaptic formation and consolidation. In addition, the lumbar spinal cord has a locomotor center, called the central pattern generator (CPG), which can be activated nonspecifically with electrical stimulation or neurotransmitters to produce walking. The CPG is an obvious target to reconnect after SCI. Stimulating motor cortex, spinal cord, or peripheral nerves can modulate lumbar spinal cord excitability. Motor cortex stimulation causes long-term changes in spinal reflexes and synapses, increases sprouting of the corticospinal tract, and restores skilled forelimb function in rats. Long used to treat chronic pain, motor cortex stimuli modify lumbar spinal network excitability and improve lower extremity motor scores in humans. Similarly, epidural spinal cord stimulation has long been used to treat pain and spasticity. Subthreshold epidural stimulation reduces the threshold for locomotor activity. In 2011, Harkema et al. reported lumbosacral epidural stimulation restores motor control in chronic motor complete patients. Peripheral nerve or functional electrical stimulation (FES) has long been used to activate sacral nerves to treat bladder and pelvic dysfunction and to augment motor function. In theory, FES should facilitate synaptic formation and motor recovery after regenerative therapies. Upcoming clinical trials provide unique opportunities to test the theory.

Effect of robotic-assisted gait training in patients with incomplete spinal cord injury

Objective

To determine the effect of robotic-assisted gait training (RAGT) compared to conventional overground training.

Methods

Sixty patients with motor incomplete spinal cord injury (SCI) were included in a prospective, randomized clinical trial by comparing RAGT to conventional overground training. The RAGT group received RAGT three sessions per week at duration of 40 minutes with regular physiotherapy in 4 weeks. The conventional group underwent regular physiotherapy twice a day, 5 times a week. Main outcomes were lower extremity motor score of American Spinal Injury Association impairment scale (LEMS), ambulatory motor index (AMI), Spinal Cord Independence Measure III mobility section (SCIM3-M), and walking index for spinal cord injury version II (WISCI-II) scale.

Results

At the end of rehabilitation, both groups showed significant improvement in LEMS, AMI, SCIM3-M, and WISCI-II. Based on WISCI-II, statistically significant improvement was observed in the RAGT group. For the remaining variables, no difference was found.

Conclusion

RAGT combined with conventional physiotherapy could yield more improvement in ambulatory function than conventional therapy alone. RAGT should be considered as one additional tool to provide neuromuscular reeducation in patient with incomplete SCI.