Effects of high frequency repetitive transcranial magnetic stimulation on KCC2 expression in rats with spasticity following spinal cord injury

Effects of non-invasive brain stimulation on motor function after spinal cord injury: a systematic review and meta-analysis

BACKGROUND

In recent years, non-invasive brain stimulation (NIBS) has been used for motor function recovery. However, the effects of NIBS in populations with spinal cord injury (SCI) remain unclear. This study aims to conduct a meta-analysis of the existing evidence on the effects and safety of NIBS against sham groups for motor dysfunction after SCI to provide a reference for clinical decision-making.

METHODS

Two investigators systematically screened English articles from PubMed, MEDLINE, Embase, and Cochrane Library for prospective randomized controlled trials regarding the effects of NIBS in motor function recovery after SCI. Studies with at least three sessions of NIBS were included. We assessed the methodological quality of the selected studies using the evidence-based Cochrane Collaboration's tool. A meta-analysis was performed by pooling the standardized mean difference (SMD) with 95% confidence intervals (CI).

RESULTS

A total of 14 randomized control trials involving 225 participants were included. Nine studies used repetitive transcranial magnetic stimulation (rTMS) and five studies used transcranial direct current stimulation (tDCS). The meta-analysis showed that NIBS could improve the lower extremity strength (SMD = 0.58, 95% CI = 0.02-1.14, P = 0.004), balance (SMD = 0.64, 95% CI = 0.05-1.24, P = 0.03), and decrease the spasticity (SMD = - 0.64, 95% CI = - 1.20 to - 0.03, P = 0.04). However, the motor ability of the upper extremity in the NIBS groups was not statistically significant compared with those in the control groups (upper-extremity strength: P = 0.97; function: P = 0.56; and spasticity: P = 0.12). The functional mobility in the NIBS groups did not reach statistical significance when compared with the sham NIBS groups (sham groups). Only one patient reported seizures that occurred during stimulation, and no other types of serious adverse events were reported.

CONCLUSION

NIBS appears to positively affect the motor function of the lower extremities in SCI patients, despite the marginal P-value and the high heterogeneity. Further high-quality clinical trials are needed to support or refute the use and optimize the stimulation parameters of NIBS in clinical practice.

Safety and effects of a therapeutic 15 Hz rTMS protocol administered at different suprathreshold intensities in able-bodied individuals

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) remains a promising strategy for neurorehabilitation. The stimulation intensity (SI) influences the aftereffects observed. Here, we examined whether single sessions of a 15 Hz rTMS protocol, administered at suprathreshold SI, can be safely administered to able-bodied (AB) individuals. Six right-handed men were included in this pilot study. HF-rTMS was delivered over the right M1, in 10 trains of 75 biphasic stimuli at 15 Hz, at 105-120% of the individual resting motor threshold (RMT). To assess safety, electromyography (EMG) was monitored to control for signs of spread of excitation and brief EMG burst (BEB) after stimulation. Additionally, TMS side effects questionnaires and the numeric rating scale (NRS) were administered during each session. We assessed corticospinal excitability (CSE) and motor performance changes with measures of resting (rMEP) and active (aMEP) motor evoked potential and grip strength and box and blocks test (BBT) scores, respectively. Overall, the sessions were tolerated and feasible without any pain development. However, EMG analysis during 15 Hz rTMS administration revealed increased BEB frequency with SI. Statistical models revealed an increase of CSE at rest (rMEP) but not during active muscle contraction (aMEP). No linear relationship was observed between 15 Hz rTMS SI and rMEP increase. No significant changes were highlighted for motor performance measures. Although feasible and tolerable by the AB individuals tested, the results demonstrate that when administered at suprathreshold intensities (≥ 105% RMT) the 15 Hz rTMS protocol reveals signs of persistent excitation, suggesting that safety precautions and close monitoring of participants should be performed when testing such combinations of high-intensity and high-frequency stimulation protocols. The results also give insight into the nonlinear existent relationship between the SI and HF-rTMS effects on CSE.NEW & NOTEWORTHY The results of this pilot study show the effects of a therapeutically promising 15 Hz repetitive transcranial magnetic stimulation (rTMS) protocol, administered at different suprathreshold intensities in able-bodied individuals. Although tolerable and feasible with a neuromodulatory potential, 15 Hz rTMS might result in persistent excitability that needs to be closely monitored if administered at suprathreshold stimulation intensity. These results reaffirm the importance of feasibility studies, especially in translational animal-to-human research.

Stimulation Parameters Used During Repetitive Transcranial Magnetic Stimulation for Motor Recovery and Corticospinal Excitability Modulation in SCI: A Scoping Review

There is a growing interest in non-invasive stimulation interventions as treatment strategies to improve functional outcomes and recovery after spinal cord injury (SCI). Repetitive transcranial magnetic stimulation (rTMS) is a neuromodulatory intervention which has the potential to reinforce the residual spinal and supraspinal pathways and induce plasticity. Recent reviews have highlighted the therapeutic potential and the beneficial effects of rTMS on motor function, spasticity, and corticospinal excitability modulation in SCI individuals. For this scoping review, we focus on the stimulation parameters used in 20 rTMS protocols. We extracted the rTMS parameters from 16 published rTMS studies involving SCI individuals and were able to infer preliminary associations between specific parameters and the effects observed. Future investigations will need to consider timing, intervention duration and dosage (in terms of number of sessions and number of pulses) that may depend on the stage, the level, and the severity of the injury. There is a need for more real vs. sham rTMS studies, reporting similar designs with sufficient information for replication, to achieve a significant level of evidence regarding the use of rTMS in SCI.

Fibromyalgia Pain and Depression: An Update on the Role of Repetitive Transcranial Magnetic Stimulation

Fibromyalgia is a musculoskeletal pain of different parts of the body, which is also associated with fatigue, lack of sleep, cognition deficits, family history, gender bias, and other disorders such as osteoarthritis and rheumatoid arthritis. It is generally initiated after trauma, surgery, infection, or stress. Fibromyalgia often coexists with several other conditions or disorders such as temporomandibular joint disorders, bowel and bladder syndrome, anxiety, depression, headaches, and interstitial cystitis. While there is no permanent cure for fibromyalgia, some interventions are available with multiple side effects. rTMS (repetitive transcranial magnetic stimulation), a noninvasive management strategy is used widely for various pain-related etiologies including fibromyalgia in both the laboratory and clinical settings. In this Review, we discuss the role and mechanism of action of rTMS in fibromyalgia patients and on associated comorbidities including anxiety, pain, depression, neurotransmitter alterations, sleep disorders, and overall quality of life of the patients suffering from this chronic problem. We also provide an update on the rTMS application in the clinical trials of fibromyalgia patients and prospective management therapy for multiple problems that these patients suffer.