Lumbar repetitive magnetic stimulation reduces spastic tone increase of the lower limbs

Identifying spinal tracts transmitting distant effects of trans-spinal magnetic stimulation

Estimating the state of tract-specific inputs to spinal motoneurons is critical to understanding movement deficits induced by neurological injury and potential pathways to recovery but remains challenging in humans. In this study, we explored the capability of trans-spinal magnetic stimulation (TSMS) to modulate distal reflex circuits in young adults. TSMS was applied over the thoracic spine to condition soleus H-reflexes involving sacral-level motoneurons. Three TSMS intensities below the motor threshold were applied at interstimulus intervals (ISIs) between 2 and 20 ms relative to peripheral nerve stimulation (PNS). Although low-intensity TSMS yielded no changes in H-reflexes across ISIs, the two higher stimulus intensities yielded two phases of H-reflex inhibition: a relatively long-lasting period at 2- to 9-ms ISIs, and a short phase at 11- to 12-ms ISIs. H-reflex inhibition at 2-ms ISI was uniquely dependent on TSMS intensity. To identify the candidate neural pathways contributing to H-reflex suppression, we constructed a tract-specific conduction time estimation model. Based upon our model, H-reflex inhibition at 11- to 12-ms ISIs is likely a manifestation of orthodromic transmission along the lateral reticulospinal tract. In contrast, the inhibition at 2-ms ISI likely reflects orthodromic transmission along sensory fibers with activation reaching the brain, before descending along motor tracts. Multiple pathways may contribute to H-reflex modulation between 4- and 9-ms ISIs, orthodromic transmission along sensorimotor tracts, and antidromic transmission of multiple motor tracts. Our findings suggest that noninvasive TSMS can influence motoneuron excitability at distal segments and that the contribution of specific tracts to motoneuron excitability may be distinguishable based on conduction velocities.NEW & NOTEWORTHY This study explored the capability of trans-spinal magnetic stimulation (TSMS) over the thoracic spine to modulate distal reflex circuits, H-reflexes involving sacral-level motoneurons, in young adults. TSMS induced two inhibition phases of H-reflex across interstimulus intervals (ISIs): a relatively long-lasting period at 2- to 9-ms ISIs, and a short phase at 11- to 12-ms ISIs. An estimated probability model constructed from tract-specific conduction velocities allowed the identification of potential spinal tracts contributing to the changes in motoneuron excitability.

Effect of Repetitive Peripheral Magnetic Stimulation on Patients With Low Back Pain: A Meta-analysis of Randomized Controlled Trials

OBJECTIVE

The purpose of this meta-analysis was to investigate the effects of repetitive peripheral magnetic stimulation (rPMS) on pain intensity, functional mobility, and kinesiophobia in individuals with low back pain (LBP).

DATA SOURCES

The PubMed, Physiotherapy Evidence Database, Embase, Cochrane Library, and Web of Science databases were systematically searched from inception until November 25, 2022.

STUDY SELECTION

Eligible randomized controlled trials contained information on the population (LBP), intervention (rPMS), and outcomes (pain intensity, functional mobility, and kinesiophobia). Participants in the rPMS intervention group were compared with those in sham or other control groups. Two independent researchers searched for, screened, and qualified the articles.

DATA EXTRACTION

Two independent researchers extracted key information from each eligible study. The authors' names, year of publication, setting, total sample size, rPMS parameters, baseline/mean difference (MD), and 95% confidence interval (CI) were extracted using a standardized form, and the methodological quality was assessed using the Physiotherapy Evidence Database score and GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) system.

DATA SYNTHESIS

Of 733 studies identified, 6 randomized controlled trials (n = 139) were included for meta-analysis. Compared with sham rPMS or other therapy, rPMS showed significant efficacy in reducing pain intensity (visual analog scale: MD, -1.89; 95% CI, -3.32 to -0.47; P<.05; very low-quality evidence). Significant efficacy was also found in terms of functional disability (Oswestry Disability Index: MD, -8.39; 95% CI, -13.65 to -3.12; P<.001; low-quality evidence). However, there was no statistically significant between-group difference on the Tampa scale of kinesiophobia (MD, -1.81; 95% CI, -7.60 to 3.98; P>.05; very low-quality evidence).

CONCLUSIONS

This meta-analysis found very low- to low-quality evidence that rPMS can be used to reduce pain intensity and improve functional disability in individuals with LBP. However, no significant effect of rPMS on kinesiophobia was found.

Role of Cervical Spinal Magnetic Stimulation in Improving Posture and Functional Ambulation of Patients with Relapsing Remitting Multiple Sclerosis

Balance impairment is one of the hallmarks of early MS. Proprioceptive deficit was found to be one of the main causes of this imbalance. The cervical enlargement has a strong proprioceptive system, with its projections to the reticular formation and the central pattern generators, helping in rhythmic pattern generation and alternate leg movements. Repetitive trans-spinal magnetic stimulation (rTSMS) is a noninvasive technique, which can trigger massive proprioceptive afferents. Therefore, it has the potential of improving proprioceptive deficits and motor control. Objective. To determine the effectiveness of repetitive cervical magnetic stimulation in improving functional ambulation of patients with relapsing remitting multiple sclerosis (RRMS). Design. Prospective sequential clinical trial. Setting. University and academic hospital. Participants. A total of 32 participants ( $N=32$ ) with RRMS. Interventions. Outpatient rehabilitation. The 32 patients received 10 sessions over two weeks of 20 Hz cervical spinal magnetic stimulation (SMS). Both groups were assessed at baseline, after 2 weeks, then one month later. Patients were enrolled as a control group at first and received Sham SMS, and then a wash out period of one month was done for all the patients, followed by a baseline assessment. Second, the same 32 patients rejoined as the active group, which received real magnetic stimulation. Both groups performed an intensive physical therapy program with the spinal magnetic stimulation. Main Outcome Measures. Extended Disability status score (EDSS), Timed up and Go test (TUG), Mini-Best test, dynamic posturography sensory organization composite score, and motor composite score. Results. Thirty-two RRMS patients with EDSS range from 1.5 to 6. They showed statistically significant difference between active and control groups in Mini-Best test score. We divided our patients according to EDSS into 3 subgroups: (a) mild: ≤2.5, (b) moderate: 3-5.5, and (c) severe: ≥6. Mild cases showed significant differences in EDSS score, TUG test, Mini-Best test, and dynamic posturography sensory composite scale. The effect size between the different patient subgroups was also measured and showed highly significant improvements in all measured parameters among our mild patients, indicating that this subgroup could be the best responders to cervical repetitive high-frequency magnetic stimulation. Moderate cases showed highly significant improvement in TUG score and Mini-Best test and significant change in EDSS score and the dynamic posturography sensory composite score. Severe cases showed only significant improvements in TUG, Mini-Best test, and sensory composite score. Conclusion. Cervical repetitive magnetic stimulation can help improve balance and functional ambulation and decreases the risk of falls in RRMS patients, especially in the mild, low disability cases.

Non-invasive brain-spine interface: Continuous control of trans-spinal magnetic stimulation using EEG

Brain-controlled neuromodulation has emerged as a promising tool to promote functional recovery in patients with motor disorders. Brain-machine interfaces exploit this neuromodulatory strategy and could be used for restoring voluntary control of lower limbs. In this work, we propose a non-invasive brain-spine interface (BSI) that processes electroencephalographic (EEG) activity to volitionally control trans-spinal magnetic stimulation (ts-MS), as an approach for lower-limb neurorehabilitation. This novel platform allows to contingently connect motor cortical activation during leg motor imagery with the activation of leg muscles via ts-MS. We tested this closed-loop system in 10 healthy participants using different stimulation conditions. This BSI efficiently removed stimulation artifacts from EEG regardless of ts-MS intensity used, allowing continuous monitoring of cortical activity and real-time closed-loop control of ts-MS. Our BSI induced afferent and efferent evoked responses, being this activation ts-MS intensity-dependent. We demonstrated the feasibility, safety and usability of this non-invasive BSI. The presented system represents a novel non-invasive means of brain-controlled neuromodulation and opens the door towards its integration as a therapeutic tool for lower-limb rehabilitation.

Controversies and Clinical Applications of Non-Invasive Transspinal Magnetic Stimulation: A Critical Review and Exploratory Trial in Hereditary Spastic Paraplegia

Magnetic stimulation is a safe, non-invasive diagnostic tool and promising treatment strategy for neurological and psychiatric disorders. Although most studies address transcranial magnetic stimulation, transspinal magnetic stimulation (TsMS) has received recent attention since trials involving invasive spinal cord stimulation showed encouraging results for pain, spasticity, and Parkinson’s disease. While the effects of TsMS on spinal roots is well understood, its mechanism of action on the spinal cord is still controversial. Despite unclear mechanisms of action, clinical benefits of TsMS have been reported, including improvements in scales of spasticity, hyperreflexia, and bladder and bowel symptoms, and even supraspinal gait disorders such as freezing and camptocormia. In the present study, a critical review on the application of TsMS in neurology was conducted, along with an exploratory trial involving TsMS in three patients with hereditary spastic paraplegia. The goal was to understand the mechanism of action of TsMS through H-reflex measurement at the unstimulated lumbosacral level. Although limited by studies with a small sample size and a low to moderate effect size, TsMS is safe and tolerable and presents consistent clinical and neurophysiological benefits that support its use in clinical practice.

Efficacy of Repetitive Trans-spinal Magnetic Stimulation for Patients with Parkinson's Disease: a Randomised Controlled Trial

We evaluated the effect of repetitive trans-spinal magnetic stimulation (rTSMS) in patients with Parkinson's disease (PD) in a randomised, single-blind study. Participants were hospitalised and administered a single trial of rTSMS or sham treatment 2 days a week for 4 weeks. In addition, all participants underwent rehabilitation 5 days a week for 4 weeks. The primary outcome was the difference between the two groups in the mean change from baseline to post-training in the total score on the Unified Parkinson's Disease Rating Scale (UPDRS). Secondary endpoints included the differences between the two groups in the mean change on the UPDRS part III (motor) score and the Timed Up and Go (TUG) score. Eligible participants were randomly assigned to either the rTSMS group (n = 50) or sham group (n = 50). The between-group difference in mean change in the total UPDRS score was 10.28 (95% confidence interval (CI), 4.42 to 16.13; P = 0.014) immediately after intervention from baseline, 5.04 (95% CI, - 5.41 to 15.50; P = 0.024) 3 months after intervention from baseline and 2.38 (95% CI, 7.18 to 11.85; P = 0.045) 6 months after intervention from baseline. Significant differences between groups in UPDRS part III and TUG scores were maintained more strictly than those in the UPDRS total score. These results strongly indicate that rTSMS promotes the effect of rehabilitation on motor function in patients with PD.

Effects of Peripheral Electromagnetic Fields on Spasticity: A Systematic Review

Electromagnetic fields are emerging as a therapeutic option for patients with spasticity. They have been applied at brain or peripheral level. The effects of electromagnetic fields applied to the brain have been extensively studied for years in spasticity, but not so at the peripheral level. Therefore, the purpose of our work is to analyze the effects of electromagnetic fields, applied peripherally to spasticity. A systematic review was conducted resulting in 10 clinical trials. The frequency ranged from 1 Hz to 150 Hz, with 25 Hz being the most commonly used and the intensity it was gradually increased but there was low homogeneity in how it was increased. Positive results on spasticity were found in 80% of the studies: improvements in stretch reflex threshold, self questionnaire about difficulties related to spasticity, clinical spasticity score, performance scale, Ashworth scale, spastic tone, Hmax/Mmax Ratio and active and passive dorsal flexion. However, results must be taken with caution due to the large heterogeneity and the small number of articles. In future studies, it would be interesting to agree on the parameters to be used, as well as the way of assessing spasticity, to be more objective in the study of their effectiveness.

Spinal cord stimulation research in the restoration of motor, sensory and autonomic function for individuals living with spinal cord injuries: A scoping review

OBJECTIVE

To describe the status of spinal cord stimulation (SCS) research for the improvement of motor, sensory and autonomic function for individuals living with a spinal cord injury (SCI).

DATA SOURCES

This scoping review identified original research published prior to March 31, 2021, via literature searches using Medline, EMBASE, PubMed, Science Direct, CINAHL, Sport Discus, Web of Science, as well as a targeted search for well-known principal investigators. Search terms included permutations of "spinal cord stimulation", "epidural spinal cord stimulation", "transcutaneous spinal cord stimulation", "magnetic spinal cord stimulation" and "neuromodulation".

STUDY SELECTION

Studies were included if they: 1) were in English, 2) presented original research on humans living with a SCI, and 3) investigated at least one of the three forms of SCS.

DATA EXTRACTION

Extracted data included: authors, publication year, participant characteristics, purpose, study design, stimulation (device, location, parameters,) primary outcomes, and adverse events.

DATA SYNTHESIS

As a scoping review the extracted data was tabulated and presented descriptively. Themes and gaps in the literature were identified and reported. Of the 5,754 articles screened, 103 articles were included (55 epidural, 36 transcutaneous and 12 magnetic). The primary research design was a case study or series with only a single randomized clinical trial. Motor recovery was the most common primary outcome for epidural and transcutaneous SCS studies whereas bowel and bladder outcomes were most common for magnetic. Seventy percent of the studies included 10 or fewer participants, and 18 articles documented at least one adverse event. Incomplete stimulation parameter descriptions were noted across many studies. No articles mentioned direct engagement of consumers or advocacy groups.

CONCLUSION

This review identified a need for more robust study designs, larger sample sizes, comparative studies, improved reporting of stimulation parameters, adverse event data, and alignment of outcomes with the priorities of the SCI community.

Modulation of H-reflex responses and frequency-dependent depression by repetitive spinal electromagnetic stimulation: From rats to humans and back to chronic spinal cord injured rats

The lack of propagation of signals through survived fibers is among the major reasons for functional loss after incomplete spinal cord injury (SCI). Our recent results of animal studies demonstrate that spinal electromagnetic stimulation (SEMS) can enhance transmission in damaged spinal cord, and this type of modulation depends on the function of NMDA receptors at the neuronal networks below the injury level. Here, our pilot human study revealed that administration of repetitive SEMS induced long‐lasting modulation of H‐responses in both healthy and participants with chronic SCI. In order to understand the mechanisms underlying these effects, we have used an animal model and examined effects of SEMS on H‐responses. Effects of SEMS on H‐responses, frequency‐dependent depression (FDD) of H‐reflex, and possible underlying mechanisms have been examined in both naïve and rats with SCI. Our results demonstrate that consistent with the effects of SEMS on H‐reflex seen in humans, repetitive SEMS induced similar modulation in excitability of peripheral nerve responses in both non‐injured and rats with SCI. Importantly, our results confirmed the reduced FDD of H‐reflex in SCI animals and revealed that SEMS was able to recover FDD in rats with chronic SCI. Using intraspinal injections of the NMDA receptor blocker MK‐801, we have identified NMDA receptors as an important contributor to these SEMS‐induced effects in rats with SCI. These results identify SEMS as a novel non‐invasive technique for modulation of neuro‐muscular circuits and, importantly, modulation of spinal networks after chronic SCI.

Electric Field Distribution during Non-Invasive Electric and Magnetic Stimulation of the Cervical Spinal Cord. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019;2019:5898-5901. [PMID: 31947192 DOI: 10.1109/embc.2019.8857129]

Experimental studies on transcutaneous spinal cord direct current and magnetic stimulation (tsDCS and tsMS) show promising results in the neuromodulation of spinal sensory and motor pathways, with possible application in spinal functional rehabilitation. Modelling studies on the electric field (EF) distribution during tsDCS and tsMS are powerful tools to understand the underlying biophysics and to select and optimize stimulation protocols for a specific clinical target. The study presented here compares the EF during cervical tsDCS and tsMS. The EF predictions show the same spatial profiles along the cervical spinal cord using both types of stimulation. tsMS presents higher average magnitudes per spinal segment, with a maximum value of 14.61 V/m, whereas tsDCS is approximately 30 times lower, reaching 0.44 V/m. According to previous studies, tsDCS and tsMS induce EF values which are sufficient for spinal neuromodulation.

Therapeutic Stimulation for Restoration of Function After Spinal Cord Injury

Paralysis due to spinal cord injury can severely limit motor function and independence. This review summarizes different approaches to electrical stimulation of the spinal cord designed to restore motor function, with a brief discussion of their origins and the current understanding of their mechanisms of action. Spinal stimulation leads to impressive improvements in motor function along with some benefits to autonomic functions such as bladder control. Nonetheless, the precise mechanisms underlying these improvements and the optimal spinal stimulation approaches for restoration of motor function are largely unknown. Finally, spinal stimulation may augment other therapies that address the molecular and cellular environment of the injured spinal cord. The fact that several stimulation approaches are now leading to substantial and durable improvements in function following spinal cord injury provides a new perspectives on the previously "incurable" condition of paralysis.

Now is the Critical Time for Engineered Neuroplasticity

Recent advances in neuroscience and devices are ushering in a new generation of medical treatments. Engineered biodevices are demonstrating the potential to create long-term changes in neural circuits, termed neuroplasticity. Thus, the approach of engineering neuroplasticity is rapidly expanding, building on recent demonstrations of improved quality of life for people with movement disorders, epilepsy, and spinal cord injury. In addition, discovering the fundamental mechanisms of engineered neuroplasticity by leveraging anatomically well-documented systems like the spinal cord is likely to provide powerful insights into solutions for other neurotraumas, such as stroke and traumatic brain injury, as well as neurodegenerative disorders, such as Alzheimer's, Parkinson disease, and multiple sclerosis. Now is the time for advancing both the experimental neuroscience, device development, and pioneering human trials to reap the benefits of engineered neuroplasticity as a therapeutic approach for improving quality of life after spinal cord injury.

Effects of Neuromuscular Electrical Stimulation on the Frequency of Skeletal Muscle Cramps: A Prospective Controlled Clinical Trial

OBJECTIVES

We investigated if neuromuscular electrical stimulation (NMES) of calf muscles prevents spontaneous calf cramps.

MATERIALS AND METHODS

In 19 individuals affected by more than or equal to one calf cramp per week the gastrocnemius of the predominantly affected leg was stimulated twice a week (intervention leg, IL) over six weeks (3 × 6 stimulation trains at 30 Hz above the individual cramp threshold frequency). The other leg served as control (CL). The participants were advised to record all spontaneous muscle cramps from two weeks before the intervention until two weeks after the last NMES session.

RESULTS

The number of spontaneous calf cramps in the two weeks after the intervention was 78% lower (2.1 ± 6.8 cramps) in the stimulated (p < 0.001) and 63% lower (2.0 ± 6.9 cramps) in the unstimulated calves (p < 0.001), when compared to the two weeks prior to the intervention (IL: 9.6 ± 12.4 cramps; CL: 5.5 ± 12.7 cramps). Only in the IL, this improvement was accompanied by an increase in the cramp threshold frequency from 15.5 ± 8.5 Hz before the NMES intervention to 21.7 ± 12.4 Hz after the intervention. The severity of the remaining calf cramps tended to be lower in both legs after the intervention.

CONCLUSIONS

The applied stimulation protocol seems to provide an effective prevention strategy in individuals affected by regular calf cramps.

Regenerative Rehabilitation: Combining Stem Cell Therapies and Activity-Dependent Stimulation

The number of clinical trials in regenerative medicine is burgeoning, and stem cell/tissue engineering technologies hold the possibility of becoming the standard of care for a multitude of diseases and injuries. Advances in regenerative biology reveal novel molecular and cellular targets, with potential to optimize tissue healing and functional recovery, thereby refining rehabilitation clinical practice. The purpose of this review is to (1) highlight the potential for synergy between the fields of regenerative medicine and rehabilitation, a convergence of disciplines known as regenerative rehabilitation; (2) provide translational examples of regenerative rehabilitation within the context of neuromuscular injuries and diseases; and (3) offer recommendations for ways to leverage activity dependence via combined therapy and technology, with the goal of enhancing long-term recovery. The potential clinical benefits of regenerative rehabilitation will likely become a critical aspect in the standard of care for many neurological and musculoskeletal disorders.

Passive cycling in neurorehabilitation after spinal cord injury: A review

CONTEXT/OBJECTIVE

Passive cycling (PC) may represent a potential alternative neurorehabilitation program for patients who are too weak or medically unstable to repeatedly practice active movements. We review here the most important animal and human studies addressing PC after spinal cord injury (SCI).

METHODS

A MEDLINE search was performed using following terms: "passive", "cycling", "pedaling", "pedalling","spinal cord injury".

RESULTS

Experimental studies revealed that PC modulated spinal reflex and reduced spasticity. PC also reduced autonomic dysreflexia and elicited cardio-protective effects. Increased levels of mRNA for brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor and neurotrophin-4 were found. In contrast, human studies failed to show an effect of PC on spasticity reduction and did not support its application for prevention of cardiovascular disease-related secondary complications.

CONCLUSION

Available evidence to support the use of PC as standard treatment in patients with SCI is still rather limited. Since it is conceivable that PC motion could elicit sensory inputs to activate cortical structures and induce cortical plasticity changes leading to improved lower limb motor performance, further carefully designed prospective studies in subjects with SCI are needed.

Spinal electro-magnetic stimulation combined with transgene delivery of neurotrophin NT-3 and exercise: novel combination therapy for spinal contusion injury

Our recent terminal experiments revealed that administration of a single train of repetitive spinal electromagnetic stimulation (sEMS; 35 min) enhanced synaptic plasticity in spinal circuitry following lateral hemisection spinal cord injury. In the current study, we have examined effects of repetitive sEMS applied as a single train and chronically (5 wk, every other day) following thoracic T10 contusion. Chronic studies involved examination of systematic sEMS administration alone and combined with exercise training and transgene delivery of neurotrophin [adeno-associated virus 10-neurotrophin 3 (AAV10-NT3)]. Electrophysiological intracellular/extracellular recordings, immunohistochemistry, behavioral testing, and anatomical tracing were performed to assess effects of treatments. We found that administration of a single sEMS train induced transient facilitation of transmission through preserved lateral white matter to motoneurons and hindlimb muscles in chronically contused rats with effects lasting for at least 2 h. These physiological changes associated with increased immunoreactivity of GluR1 and GluR2/3 glutamate receptors in lumbar neurons. Systematic administration of sEMS alone for 5 wk, however, was unable to induce cumulative improvements of transmission in spinomuscular circuitry or improve impaired motor function following thoracic contusion. Encouragingly, chronic administration of sEMS, followed by exercise training (running in an exercise ball and swimming), induced the following: 1) sustained strengthening of transmission to lumbar motoneurons and hindlimb muscles, 2) better retrograde transport of anatomical tracer, and 3) improved locomotor function. Greatest improvements were seen in the group that received exercise combined with sEMS and AAV-NT3.

Immediate effect of spinal magnetic stimulation on camptocormia in Parkinson's disease

OBJECTIVES

Spinal cord stimulation is a potential therapeutic option for the treatment of Parkinson's disease (PD)-associated symptoms. Repetitive trans-spinal magnetic stimulation (rTSMS) is a non-invasive and safe alternative for stimulation of spinal pathways that has not been studied for therapeutic efficacy in PD. We assessed the benefits of rTSMS on camptocormia, an often treatment-resistant postural abnormality observed in PD patients.

METHODS

We compared rTSMS to sham stimulation in PD patients with camptocormia in a single-centre, randomised, single-blind, crossover, placebo-controlled study. PD patients with camptocormia were administered a single trial of rTSMS (a train of 40 stimuli) or sham treatment followed 1 week later by the alternate treatment. Primary outcome measure was thoracolumbar spine flexion angle in the standing position immediately after the trial.

RESULTS

Of 320 PD patients examined, 37 had concomitant camptocormia and were randomly assigned to either the rTSMS first group (n=19) or sham first group (n=18). Flexion angle in the standing position decreased by a mean of 10.9° (95% CI 8.1 to 13.65) after rTSMS but remained unchanged after sham stimulation (mean, -0.1°; 95% CI -0.95 to 0.71). The flexion angle while sitting (secondary outcome) decreased by 8.1° (95% CI 5.89 to 10.25) after rTSMS, whereas sham treatment had no significant effect (mean, -0.8°; 95% CI -1.62 to 0.05).

CONCLUSIONS

We found an immediate beneficial effect of rTSMS on camptocormia in PD patients. Although the effect was transient, this successful trial justifies further studies to test if repeated rTSMS treatments can induce longer term improvements in camptocormia associated with PD.

CLINICAL TRIAL REGISTRATION

UMIN Clinical Trials Registry: UMIN000011495.

Noninvasive and painless magnetic stimulation of nerves improved brain motor function and mobility in a cerebral palsy case

Motor deficits in cerebral palsy disturb functional independence. This study tested whether noninvasive and painless repetitive peripheral magnetic stimulation could improve motor function in a 7-year-old boy with spastic hemiparetic cerebral palsy. Stimulation was applied over different nerves of the lower limbs for 5 sessions. We measured the concurrent aftereffects of this intervention on ankle motor control, gait (walking velocity, stride length, cadence, cycle duration), and function of brain motor pathways. We observed a decrease of ankle plantar flexors resistance to stretch, an increase of active dorsiflexion range of movement, and improvements of corticospinal control of ankle dorsiflexors. Joint mobility changes were still present 15 days after the end of stimulation, when all gait parameters were also improved. Resistance to stretch was still lower than prestimulation values 45 days after the end of stimulation. This case illustrates the sustained effects of repetitive peripheral magnetic stimulation on brain plasticity, motor function, and gait. It suggests a potential impact for physical rehabilitation in cerebral palsy.

Effects of conditioning peripheral repetitive magnetic stimulation in patients with complex regional pain syndrome

OBJECTIVES

We tested whether repetitive magnetic stimulation (rMS) induces an afferent input to the spinocerebral tract in patients with complex regional pain syndrome (CRPS).

METHODS

Cortical and spinal motor evoked potentials (cMEP and sMEP), as well as the contra- and ipsilateral silent period (cCSP and iCSP), were recorded in patients with CRPS type I before and after conditioning rMS, applied at cervical nerve roots innervating affected muscles. Patients were compared with a group of healthy subjects.

RESULTS

In the group of patients we found that cMEP amplitudes were always significantly smaller for both hemispheres. In the group of healthy subjects we found a significant prolongation of the cCSP and iCSP after rMS. This was absent in patients. SMEP were always unchanged in both groups.

DISCUSSION

This led us to the explanation that the afferent input to the motor cortical system in CRPS patients is less effective than in healthy subjects.

The physiological basis of neurorehabilitation--locomotor training after spinal cord injury

Advances in our understanding of the physiological basis of locomotion enable us to optimize the neurorehabilitation of patients with lesions to the central nervous system, such as stroke or spinal cord injury (SCI). It is generally accepted, based on work in animal models, that spinal neuronal machinery can produce a stepping-like output. In both incomplete and complete SCI subjects spinal locomotor circuitries can be activated by functional training which provides appropriate afferent feedback. In motor complete SCI subjects, however, motor functions caudal to the spinal cord lesion are no longer used resulting in neuronal dysfunction. In contrast, in subjects with an incomplete SCI such training paradigms can lead to improved locomotor ability. Appropriate functional training involves the facilitation and assistance of stepping-like movements with the subjects’ legs and body weight support as far as is required. In severely affected subjects standardized assisted locomotor training is provided by body weight supported treadmill training with leg movements either manually assisted or moved by a driven gait orthosis. Load- and hip-joint related afferent input is of crucial importance during locomotor training as it leads to appropriate leg muscle activation and thus increases the efficacy of the rehabilitative training. Successful recovery of locomotion after SCI relies on the ability of spinal locomotor circuitries to utilize specific multisensory information to generate a locomotor pattern. It seems that a critical combination of sensory cues is required to generate and improve locomotor patterns after SCI. In addition to functional locomotor training there are numbers of other promising experimental approaches, such as tonic epidural electrical or magnetic stimulation of the spinal cord, which both promote locomotor permissive states that lead to a coordinated locomotor output. Therefore, a combination of functional training and activation of spinal locomotor circuitries, for example by epidural/flexor reflex electrical stimulation or drug application (e.g. noradrenergic agonists), might constitute an effective strategy to promote neuroplasticity after SCI in the future.

[Cerebral reorganization in chronic low back pain and neurostimulation to improve motor control]

Chronic recurrent pain results in brain reorganization for cortical sensory and motor representation of muscles. This review supports the hypothesis that maladaptive plasticity in chronic low back pain patients could be associated with disorders of volitional activation of trunk/pelvis muscles and alterations of their anticipatory motor patterns for postural control. This is actually observed for the transversus abdominis muscle, an abdominal muscle that stabilizes the lumbosacral spine against external and internal postural perturbations. Indeed, voluntary activation of this muscle is more difficult in low back pain and a posterolateral translation of its cortical motor representation is observed in association with a delay of its anticipatory activation (usually observed in any focal limb movement). During physiotherapy, low back pain patients are trained to hollowing for contracting the transversus abdominis muscle, which normalizes both activation delays and cortical motor representation. This motor rehabilitation could be potentiated by peripheral repetitive magnetic stimulation directly over the nerves/muscles. This review introduces the magnetic stimulation technique and proposes to combine peripheral theta-burst stimulation to conventional therapy for increasing the functional gain. This may facilitate the activation of sensory afferents and modulate cortical plasticity to improve (or even re-activate) the sensorimotor control and possibly influence pain. Peripheral magnetic stimulation as an ancillary treatment adjuvant for promoting motor control in low back pain might also be relevant in any other neurological or musculoskeletal disorder with underlying maladaptive brain reorganization.

Combined effects of acrobatic exercise and magnetic stimulation on the functional recovery after spinal cord lesions

The objective of the study was to determine whether physical exercise combined with epidural spinal cord magnetic stimulation could improve recovery after injury of the spinal cord. Spinal cord lesioning in mice resulted in reduced locomotor function and negatively affected the muscle strength tested in vitro. Acrobatic exercise attenuated the behavioral effects of spinal cord injury. The exposure to magnetic fields facilitated further this improvement. The progress in behavioral recovery was correlated with reduced muscle degeneration and enhanced muscle contraction. The acrobatic exercise combined with stimulation with magnetic fields significantly facilitates behavioral recovery and muscle physiology in mice following spinal cord injury.

Peripheral repetitive magnetic stimulation induces intracortical inhibition in healthy subjects

OBJECTIVE

Repetitive magnetic stimulation (rMS) is mainly used in transcranial applications. Only a few works have described its potential peripheral use. The aim of this investigation was to determine if conditioning peripheral (paravertebral) rMS of the cervical nerve roots in a group of healthy subjects induces changes in motor cortical excitability.

METHODS

This was measured by means of motor evoked potentials (MEP), motor recruitment curves (RC), intracortical inhibition (ICI) and facilitation, as well as the cortical silent period (CSP) before and after repetitive stimulation. rMS was carried out by applying ten series of stimulation at 120% of resting motor threshold, each lasting 10 seconds with a frequency of 20 Hz. The nerve roots (C7/C8) of the right hand innervating the target muscles (the first dorsal interosseous) were systematically stimulated.

RESULTS

This conditioning rMS caused a significantly longer CSP (p=0.001), increased MEP amplitudes (with a tendency to significance of p=0.06) and raised ICI (p<0.05). These changes were absent on the contralateral side, as well as in the course of RC. In conclusion, previously published results that described a prolonged CSP and increased MEP amplitudes led us to speculate that conditioning peripheral rMS is, like electrical stimulation, capable of influencing motor cortical excitability.

SIGNIFICANCE

rMS might therefore be used in rehabilitative strategies for spasticity, pain or central paresis.

Differential activation and block of peripheral nerve fibers by magnetic fields

The ability to noninvasively and reversibly block conduction in peripheral nerves would have several clinical applications. As an initial step in this direction, we investigated the possibility of magnetically generating and differentially blocking activity in mammalian peripheral nerve fibers in vitro. Compound action potentials at each end of individual explanted phrenic nerves were recorded in response to currents induced at the midpoint of the nerve with an externally placed magnetic coil. Current in the coil was then reversed and the recordings repeated. In all cases, the area under the compound action potential on the virtual anode side of the magnetic stimulus was reduced (mean of 18.2 +/- 8.8%) in comparison to the area on the virtual cathode side. This indicates that peripheral nerve activity can be differentially induced by magnetic stimulation. Extension of this effect to the point of generating unidirectional action potentials in vivo may prove clinically useful in a number of contexts, such as reducing contractures secondary to spasticity and generating magnetically induced anesthesia in limbs. Further investigations of this effect seem warranted.

The effect of penile vibratory stimulation on male fertility potential, spasticity and neurogenic detrusor overactivity in spinal cord lesioned individuals

PURPOSE

Present the possibility for treatment of male infertility, spasticity, and neurogenic detrusor overactivity in spinal cord lesioned (SCL) individuals with penile vibratory stimulation (PVS).

METHOD

Obtaining reflex-ejaculation by PVS, by using a vibrator developed for this purpose. The stimulation was performed with a vibrating disc of hard plastic placed against the frenulum of the penis (amplitude > or = 2.5 mm). The vibration continued until antegrade ejaculation or for a maximum of 3 minutes followed by a pause of 1 minute before the cycle was repeated, maximally 4 times.

RESULTS

>80% SCL men are able to obtain ejaculation with PVS. Pregnancy rates obtained with home PVS and intra-vaginal insemination was 22-62% (4 studies), and with PVS or electroejaculation and intrauterine insemination/in-vitro fertilization/intracytoplasmatic sperm injection 39-64% (9 studies). PVS was demonstrated to decrease spasticity significantly when measured by the modified Ashworth scale. In addition, a decrease of the number of spontaneous EMG events which probably indicate spasms was observed. Increase in bladder capacity at leakpoint following 4 weeks of frequent ejaculation with PVS treatment was likewise demonstrated.

CONCLUSION

PVS has proved its importance for SCL male fertility, in the years to come its place in treatment of spasticity and neurogenic detrusor overactivity has to be established.

Chapter 36 Modulation of sensorimotor performances and cognition abilities induced by RPMS: clinical and experimental investigations

The investigations presented in this chapter lead to the conclusion that proprioceptive afferent inflow to the CNS induced by RPMS elicits various modulatory effects in sensorimotor and cognitive systems. Since the build-up of the conditioning effects is delayed and the effects itself are long-lasting, it has to be assumed that these effects are caused via neuromodulators. Therefore, the presented approach is promising to improve sensorimotor and cognitive disturbances after lesions in the CNS, e.g. after a stroke, by facilitation of reorganization.