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

Repetitive peripheral magnetic stimulation for preventing shoulder subluxation after stroke: a randomized controlled trial

BACKGROUND

Shoulder subluxation caused by paralysis after stroke is a serious issue affecting shoulder pain and functional prognosis. However, its preventive treatment has not been fully investigated.

AIM

To investigate the effects of repetitive peripheral magnetic stimulation (rPMS) on the prevention of shoulder subluxation.

DESIGN

A single-center, parallel-group, prospective randomized, open-blinded, end-point study.

SETTING

Convalescent rehabilitation ward.

POPULATION

We included 50 inpatients in the convalescent rehabilitation ward with post-stroke, having upper limb paralysis, and the acromio-humeral interval (AHI) was within 1/2 finger-breadth.

METHODS

A blinded computer-based allocation system was used to randomly assign patients into two groups: 1) conventional rehabilitation plus rPMS therapy (rPMS group, N=25); and 2) conventional rehabilitation alone (control group, N=25). Blinded assessors evaluated the patients before the intervention (T0), 6 weeks after (T1), and 12 weeks after (T2). The primary outcome was the change in AHIs from T0 to T1 between the groups. In contrast, the secondary outcomes were shoulder pain, spasticity, active range of motion, and Fugl-Meyer Assessment upper extremity (FMA-UE) score.

RESULTS

Twenty-two patients in the rPMS group and 24 in the control group completed T1, whereas 16 in the rPMS group and 11 in the control group completed T2. The change in AHI was significantly lower in the rPMS group than in the control group ([95% CI, -5.15 to -0.390], P=0.023). Within-group analysis showed that AHI in the rPMS group did not change significantly, whereas it increased in the control group (P=0.004). There were no significant differences between T1 and T2 within or between the groups. Moreover, AHI did not show differences in patients with severe impairment but decreased in the rPMS group in patients with mild impairment (P=0.001).

CONCLUSIONS

The rPMS may be a new modality for preventing shoulder subluxation. The association between motor impairment and the sustained effect needs to be further examined.

CLINICAL REHABILITATION IMPACT

Applying rPMS to the muscles of the paralyzed shoulder after a stroke may prevent shoulder subluxation.

Body representation underlies response of proprioceptive acuity to repetitive peripheral magnetic stimulation

Proprioceptive acuity is of great significance in basic research exploring a possible neural mechanism of fine motor control and in neurorehabilitation practice promoting motor function recovery of limb-disabled people. Moreover, body representation relies on the integration of multiple somatic sensations, including proprioception that is mainly generated in muscles and tendons of human joints. This study aimed to examine two hypotheses: First, different extension positions of wrist joint have different proprioceptive acuities, which might indicate different body representations of wrist joint in the brain. Second, repetitive peripheral magnetic stimulation (rPMS) applied peripherally to the forearm radial nerve and extensors could change proprioceptive acuity at the wrist joint. Thirty-five healthy participants were recruited then randomly divided into the real stimulation group (n = 15) and the sham stimulation group (n = 20). The participants’ non-dominant side wrist joint position sense was tested at six extension positions within the physiological joint motion range (i.e., 10°, 20°, 30°, 40°, 50°, 60°) both before stimulation and after stimulation. Results showed that proprioceptive bias (arithmetic difference of target position and replicated position) among six extension positions could be divided into lower-extension position (i.e., 10°, 20°, 30°) and higher-extension position (i.e., 40°, 50°, 60°). One session rPMS could influence proprioceptive bias in lower-extension position but not in higher-extension position. However, proprioceptive precision (standard deviation within lower-extension position and higher-extension position) was not influenced. To conclude, proprioceptive bias may vary between different wrist extension positions due to different hand postures being related to changes in body representation, and different functions relating to proprioceptive bias and proprioceptive precision may underlie two aspects of body representation.

Theta-Burst Stimulation of Forearm Muscles in Patients With Complex Regional Pain Syndrome: Influence on Brain and Clinical Outcomes

Objective: Complex regional pain syndrome (CRPS) is a common pain condition characterized by the changes in the brain that are not yet addressed by conventional treatment regimens. Repetitive peripheral magnetic stimulation (rPMS) of muscles is painless and non-invasive and can influence these changes (the induction of brain plasticity) to reduce pain and improve motricity. In patients with CRPS, this open-label pilot study tested rPMS after-effects on the pain intensity and sensorimotor control of the upper limb along with the excitability changes of the primary motor cortex (M1).

Methods: Eight patients with CRPS were enrolled in a single-session program. Patients were tested at pre- and post-rPMS over the flexor digitorum superficialis (FDS) muscle. The clinical outcomes were pain intensity, proprioception, active range of motion (ROM), and grip strength. M1 excitability was tested using the single- and paired-pulse transcranial magnetic stimulation (TMS) of M1.

Results: In our small sample study, rPMS reduced instant and week pain, improved proprioception and ROM, and reduced the hemispheric imbalance of several TMS outcomes. The more M1 contralateral to the CRPS side was hyperactivated at baseline, the more pain was reduced.

Discussion: This open-label pilot study provided promising findings for the use of rPMS in CRPS with a focus on M1 plastic changes. Future randomized, placebo-controlled clinical trials should confirm the existence of a causal relationship between the TMS outcomes and post-rPMS decrease of pain. This will favor the development of personalized treatments of peripheral non-invasive neurostimulation in CRPS.

Electroencephalography Mu Rhythm Changes and Decreased Spasticity After Repetitive Peripheral Magnetic Stimulation in Patients Following Stroke

Background: Spasticity is common among patients with stroke. Repetitive peripheral magnetic stimulation (rPMS) is a painless and noninvasive therapy that is a promising approach to reducing spasticity. However, the central mechanism of this therapy remains unclear. Changes in cortical activity and decreased spasticity after rPMS intervention require further exploration. The aim of this study was to explore the electroencephalography (EEG) mu rhythm change and decrease in spasticity after rPMS intervention in patients with stroke. Materials and methods: A total of 32 patients with spasticity following stroke were recruited in this study and assigned to the rPMS group (n = 16) or sham group (n = 16). The modified Ashworth scale, modified Tardieu scale, and Fugl-Meyer assessment of the upper extremity were used to assess changes in upper limb spasticity and motor function. Before and after the rPMS intervention, EEG evaluation was performed to detect EEG mu rhythm changes in the brain. Results: After one session of rPMS intervention, spasticity was reduced in elbow flexors (p < 0.05) and wrist flexors (p < 0.05). Upper limb motor function measured according to the Fugl-Meyer assessment was improved (p < 0.05). In the rPMS group, the power of event-related desynchronization decreased in the mu rhythm band (8-12 Hz) in the contralesional hemisphere (p < 0.05). Conclusions: The results indicate that rPMS intervention reduced spasticity. Cortical activity changes may suggest this favorable change in terms of its neurological effects on the central nervous system.

Effects of Repetitive Peripheral Magnetic Stimulation Over Vastus Lateralis in Patients After Hip Replacement Surgery

Objective

To investigate the effects of repetitive peripheral magnetic stimulation (rPMS) on the vastus lateralis (VL) in the early stage after hip replacement surgery.

Methods

Twenty-two patients who underwent hip replacement after proximal femur fracture were included in this study. After hip surgery, the experimental group was applied with 15 sessions of 10 Hz rPMS over the VL 5 times per week for 3 weeks, while the control group took sham stimulation. All patients were also given conventional physical therapy. The VL strength was measured with the root mean square (RMS) value of the VL with surface electromyography technique. The ratio of RMS values between fractured and unfractured legs and tandem stand test were used to assess standing balance. Usual gait speed was measured to evaluate gait function. Pain in two groups was assessed with visual analog scale (VAS).

Results

Both RMS value of the VL and the ratio of RMS values after rPMS were significantly improved (p<0.05). Also, tandem standing time and usual gait speed in rPMS group were dramatically increased (p<0.05). However, no significant difference in VAS was found between the two groups after 3 weeks.

Conclusion

rPMS on the VL improved muscle strength, standing balance and gait function in the early stage after hip surgery. Therefore, rPMS could be applied to patients who cannot take electrical stimulation due to pain and an unhealed wound.

Revisiting the Corticomotor Plasticity in Low Back Pain: Challenges and Perspectives

Chronic low back pain (CLBP) is a recurrent debilitating condition that costs billions to society. Refractoriness to conventional treatment, lack of improvement, and associated movement disorders could be related to the extensive brain plasticity present in this condition, especially in the sensorimotor cortices. This narrative review on corticomotor plasticity in CLBP will try to delineate how interventions such as training and neuromodulation can improve the condition. The review recommends subgrouping classification in CLBP owing to brain plasticity markers with a view of better understanding and treating this complex condition.

[The modern approaches to the prognostication of rehabilitation of the patients after stroke on an individual basis: a review of the literature and the results of original investigations]

This article was designed to analyze the results of the investigations with the purpose of elucidation of the prognostic factors relevant to the rehabilitation of the patients who survived after stroke. Special attention is given to the role of demographic (age and sex) factors and the data of the clinical, neurological, psychological, cognitive, and instrumental examination of the patients. The results of the original studies based on the treatment of 203 stroke patients are discussed in the context of modern concepts of the significance of the factors contributing to the recovery of the patients in the course of the post-stroke rehabilitation. The prognostic value of the selected factors, such as leukoareosis (for the patients presenting with hemorrhagic stroke), has been demonstrated for the first time. The new data on the duration of the rehabilitation period are presented with reference to its dependence on the type of stroke and localization of the lesions. Specifically, it is estimated to be 2 years for the patients who suffered from ischemic stroke in the brain stem, 31 months for those with ischemic stroke of the hemispherical localization, and 38 months for the patients presenting with hemorrhagic stroke (hemispherical hematoma). In addition, the data on the magnitude of the post-ischemic atrophic changes of prognostic values are presented.

Noninvasive neurostimulation in chronic stroke: a double-blind randomized sham-controlled testing of clinical and corticomotor effects

BACKGROUND

Repetitive peripheral magnetic stimulation (RPMS) is a painless and noninvasive method to produce afferents via the depolarization of the peripheral nervous system. A few studies tested RPMS after-effects on cerebral plasticity and motor recovery in stroke individuals, but evidences remain limited.

OBJECTIVES

This study aimed to explore whether RPMS could mediate improvements in corticomotor and clinical outcomes associated with ankle impairments in chronic stroke.

METHODS

Eighteen subjects with chronic stroke were randomly allocated to RPMS or sham group and compared to 14 healthy subjects. Stimulation was applied over the paretic tibialis anterior (TA). Ankle impairments on the paretic side and ipsilesional TA cortical motor representation were tested clinically and by transcranial magnetic stimulation (TMS), respectively.

RESULTS

In the RPMS group, ankle dorsiflexion mobility and maximal isometric strength increased and resistance to plantar flexor stretch decreased. The magnitude of change seemed to be related to cortical and corticospinal integrity. Sham stimulation yielded no effect. Changes in TMS outcome and their relationships with clinical improvements were limited.

CONCLUSIONS

RPMS improved ankle impairments in chronic stroke likely by a dynamic influence of sensory inputs on synaptic plasticity. The neurophysiological mechanisms potentially underlying the clinical effects are unclear. More studies are warranted to test the spinal and hemispheric changes responsible for the clinical improvements with emphasis on circuits spared by the lesion.

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 repetitive peripheral magnetic stimulation on upper-limb spasticity and impairment in patients with spastic hemiparesis: a randomized, double-blind, sham-controlled study

OBJECTIVE

To investigate short-term and long-term effects of repetitive peripheral magnetic stimulation (rpMS) on spasticity and motor function.

DESIGN

Monocentric, randomized, double-blind, sham-controlled trial.

SETTING

Neurologic rehabilitation hospital.

PARTICIPANTS

Patients (N=66) with severe hemiparesis and mild to moderate spasticity resulting from a stroke or a traumatic brain injury. The average time ± SD since injury for the intervention groups was 26 ± 71 weeks or 37 ± 82 weeks.

INTERVENTIONS

rpMS for 20 minutes or sham stimulation with subsequent occupational therapy for 20 minutes, 2 times a day, over a 2-week period.

MAIN OUTCOME MEASURES

Modified Tardieu Scale and Fugl-Meyer Assessment (arm score), assessed before therapy, at the end of the 2-week treatment period, and 2 weeks after study treatment. Additionally, the Tardieu Scale was assessed after the first and before the third therapy session to determine any short-term effects.

RESULTS

Spasticity (Tardieu >0) was present in 83% of wrist flexors, 62% of elbow flexors, 44% of elbow extensors, and 10% of wrist extensors. Compared with the sham stimulation group, the rpMS group showed short-term effects on spasticity for wrist flexors (P=.048), and long-term effects for elbow extensors (P<.045). Arm motor function (rpMS group: median 5 [4-27]; sham group: median 4 [4-9]) did not significantly change over the study period in either group, whereas rpMS had a positive effect on sensory function.

CONCLUSIONS

Therapy with rpMS increases sensory function in patients with severe limb paresis. The magnetic stimulation, however, has limited effect on spasticity and no effect on motor function.

Therapeutic effects of peripheral magnetic stimulation on traumatic brachial plexopathy: clinical and neurophysiological study

OBJECTIVE

To evaluate the therapeutic effects of peripheral repetitive magnetic stimulation (rMS) on recovery of traumatic brachial plexopathy.

PATIENTS AND METHODS

Thirty-four patients with traumatic brachial plexopathy were studied. Strength of different muscles of upper limbs was evaluated neurologically. Nerve conduction studies (NCS), upper limb F-waves and visual analogue scales (VAS) for shoulder pain were obtained for all patients. These were randomly assigned into two groups with a ratio of 2:1; each patient received conventional physical therapy modalities and active exercises as well as real or sham rMS applied over the superior trapezius muscle of the affected limb daily for 10 sessions. Patients were reassessed with the same parameters after the 5th and the 10th session, and 1 month after rMS treatment.

RESULTS

No significant between-group differences were recorded at baseline assessment. Significant improvement was observed (time X groups) after real rMS in comparison to the sham group (P=0.0001 for muscle strength and 0.01 for VAS of shoulder pain). These improvements were still present at 1 month after the end of treatment. In accordance with the clinical improvement, a significant improvement was recorded in the neurophysiological parameters in the real vs the sham group.

CONCLUSIONS

We demonstrate that peripheral rMS for 10 sessions may have positive therapeutic effects on motor recovery and pain relief in patients with traumatic brachial plexopathy. Therefore, it is a useful adjuvant in the therapy of these patients.

Translational Studies in Neurorehabilitation: From Bench to Bedside

Stroke is the leading cause of adult disability in the western world. Consensus has built over the last few years regarding the usefulness of training to improve motor disability resulting from stroke. Until recently, there were no accepted strategies to enhance the beneficial effects of training. However, the combination of basic and clinical science data over the last few years is changing this picture, and is highly relevant to the field of neurorehabilitation. Human studies in both healthy individuals and patients after brain damage demonstrate as a proof of principle that somatosensory input, cortical stimulation, interhemispheric interactions, and pharmacologic interventions can modulate cortical plasticity in neurorehabilitation after stroke. These findings strongly suggest directions in the development of novel strategies to enhance training effects on motor recovery. The intent of this review is to describe these strategies, the basic science principles on which they are based, and the clinical applications that have emerged so far.

Influence of Electric Somatosensory Stimulation on Paretic-Hand Function in Chronic Stroke

OBJECTIVE

To test the influence of electric somatosensory stimulation on performance of the Jebsen-Taylor Hand Function Test (JTHFT), a widely used assessment of functional hand motor skills, by the paretic arm in patients with chronic stroke.

DESIGN

Initially, patients trained for several sessions until reaching plateau performance on the JTHFT. Subsequently, they entered a crossover randomized study, designed to evaluate the influence of somatosensory stimulation on JTHFT performance.

SETTING

A research laboratory.

PARTICIPANTS

Nine patients with chronic stroke (>/=1.5 y) who acutely had marked weakness (paralysis of the upper extremity is evaluated as equal or below Medical Research Council [MRC] grade 2) followed by improvement to an MRC grade of 4.24+/-0.43 (range, 3.5-4.9) and Fugl-Meyer Assessment (FMA) score of 86.43%+/-2.02% at the time of testing.

INTERVENTIONS

Two hours of electric somatosensory stimulation was applied to the (1) paretic hand, (2) paretic leg, or (3) no stimulation in different sessions, in a randomized order.

MAIN OUTCOME MEASURE

The time required to complete the JTHFT was analyzed by using repeated-measures analysis of variance (ANOVA) with factors time (pre-, postintervention) and intervention (paretic hand, paretic leg, no stimulation) followed by post hoc testing.

RESULTS

Significant effects of intervention and intervention by time interaction (P<.01) on JTHFT time was revealed by repeated-measures ANOVA. Post hoc testing documented improvements in JTHFT time with paretic hand stimulation alone (P<.005), an effect that appeared more prominent in subjects with lower FMA scores.

CONCLUSIONS

Somatosensory stimulation applied to a paretic limb can benefit performance of a functional test in patients with chronic stroke. This result supports the proposal that electric sensory stimulation in combination with training protocols may enhance the benefit of customary neurorehabilitative treatments and possibly motor learning.

Enduring representational plasticity after somatosensory stimulation

Somatosensory stimulation (SS), leading to increases in motor cortical excitability, influences motor performance in patients with brain lesions like stroke. The mechanisms by which SS modulates motor function are incompletely understood. Here, we used functional magnetic resonance imaging (fMRI, blood-oxygenation-level-dependent (BOLD), and perfusion imagings simultaneously acquired in a 3 T magnet) to assess the effects of SS on thumb-movement-related activation in three regions of interest (ROI) in the motor network: primary motor cortex (M1), primary somatosensory cortex (S1), and dorsal premotor cortex (PMd) in healthy volunteers. Scans were obtained in different sessions before and after 2-h electrical stimulation applied to the median nerve at the wrist (MNS), to the skin overlying the shoulder deltoid muscle (DMS), and in the absence of stimulation (NOSTIM) in a counterbalanced design. We found that baseline perfusion intensity was comparable within and across sessions. MNS but not DMS nor NOSTIM led to an increase in signal intensity and number of voxels activated by performance of median nerve-innervated thumb movements in M1, S1, and PMd for up to 60 min. Task-related fMRI activation changes were most prominent in M1 followed by S1 and to a lesser extent in PMd. MNS elicited a displacement of the center of gravity for the thumb movement representation towards the other finger representations within S1. These results indicate that MNS leads to an expansion of the thumb representation towards other finger representations within S1, a form of plasticity that may underlie the influence of SS on motor cortical function, possibly supporting beneficial effects on motor control.