Importance and Difficulties of Pursuing rTMS Research in Acute Stroke

Efficacy of rTMS in treating functional impairment in post-stroke patients: a systematic review and meta-analysis

BACKGROUND

Most stroke patients suffer from an imbalance in blood supply, which causes severe brain damage leading to functional deficits in motor, sensory, swallowing, cognitive, emotional, and speech functions. Repetitive transcranial magnetic stimulation (rTMS) is thought to restore functions impaired during the stroke process and improve the quality of life of stroke patients. However, the efficacy of rTMS in treating post-stroke function impairment varies significantly. Therefore, we conducted a meta-analysis of the number of patients with effective rTMS in treating post-stroke dysfunction.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched. Screening and full-text review were performed by three investigators. Single-group rate meta-analysis was performed on the extracted data using a random variable model. Then subgroup analyses were performed at the levels of stroke acuity (acute, chronic, or subacute); post-stroke symptoms (including upper and lower limb motor function, dysphagia, depression, aphasia); rTMS stimulation site (affected side, unaffected side); and whether or not it was a combination therapy.

RESULTS

We obtained 8955 search records, and finally 33 studies (2682 patients) were included in the meta-analysis. The overall analysis found that effective strength (ES) of rTMS was 0.53. In addition, we found that the ES of rTMS from acute/subacute/chronic post-stroke was 0.69, 0.45, and 0.52. We also found that the ES of rTMS using high-frequency stimulation was 0.56, while the ES of rTMS using low-frequency stimulation was 0.53. From post-stroke symptoms, we found that the ES of rTMS in sensory aspects, upper limb functional aspects, swallowing function, and aphasia was 0.50, 0.52, 0.51, and 0.54. And from the site of rTMS stimulation, we found that the ES of rTMS applied to the affected side was 0.51, while the ES applied to the unaffected side was 0.54. What's more, we found that the ES of rTMS applied alone was 0.53, while the ES of rTMS applied in conjunction with other therapeutic modalities was 0.53.

CONCLUSIONS

By comparing the results of the data, we recommend rTMS as a treatment option for rehabilitation of functional impairment in patients after stroke. We also recommend that rehabilitation physicians or clinicians use combination therapy as one of the options for patients.

Optimal timing and neural loci: a scoping review on the effect of non-invasive brain stimulation on post-stroke gait and balance recovery

BACKGROUND

Little is known about the optimal timing and neural loci for applying noninvasive brain stimulation (NIBS) to promote gait and balance recovery after stroke.

OBJECTIVE

To identify the optimal timing and neural loci of NIBS for gait and balance recovery after stroke.

METHODS

We performed a PubMed search using keywords of stroke, transcranial magnetic stimulation, transcranial direct current stimulation, NIBS, balance, and gait. Interventional trials with various designs published in English were selected. Both flowcharts and tables were used for the result presentation.

RESULTS

The majority of selected 31 studies included individuals with chronic stroke and primary motor cortex (M1) stimulation. Studies' quality ranged from 4 to 10 (max = 10) on the Pedro scale. NIBS led to improvements in gait and balance in individuals with chronic and subacute stroke, yet the evidence for the acute phase of stroke is limited. Further, stimulation over the ipsilesional M1 resulted in improvement in gait and balanced performance. Stimulation over non-motor regions such as the cerebellum has been limitedly explored.

CONCLUSION

Current evidence supports the use of NIBS to the M1 in conjunction with behavioral training to improve gait and balance performance in individuals with subacute and chronic stroke. Future research is recommended to evaluate the effect of NIBS during acute stroke and over neural loci other than M1, and to implement a more rigorous method.

The Effect and Optimal Parameters of Repetitive Transcranial Magnetic Stimulation on Poststroke Dysphagia: A Meta-Analysis of Randomized Controlled Trials

Objective

The objectives of the study were to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) treatment for poststroke dysphagia (PSD) and explore the optimal stimulation parameters.

Method

The databases of Medline, Embase, Web of Science, and Cochrane Library were searched from the establishment to June 2021. All randomized controlled trials about rTMS treatment for PSD were enrolled. Dysphagia Grade (DG) and Penetration Aspiration Scale (PAS) were applied as the major dysphagia severity rating scales to evaluate the outcomes.

Results

A total of 12 clinical randomized controlled studies were included in our study. The summary effect size indicated that rTMS had a positive effect on PSD (SMD = −0.67, p < 0.001). The subgroup analysis for treatment duration and different stroke stages showed significant differences (treatment duration >5 days: SMD = −0.80, p < 0.001; subacute phase after stroke: SMD = −0.60, p < 0.001). Furthermore, no significant differences were observed among the other stimulation parameter subgroups (including stimulation frequency, location, and a single stimulation time) (p > 0.05).

Conclusion

rTMS is beneficial to the recovery of PSD patients, while an intervention of more than 5 days and in the subacute phase after stroke might bring new strategies and rational therapeutics to the treatment of PSD.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022299469.

Effects of coupling inhibitory and facilitatory repetitive transcranial magnetic stimulation on motor recovery in patients following acute cerebral infarction

BACKGROUND

The treatment for patients suffering from motor dysfunction following stroke using continuous repetitive transcranial magnetic stimulation (rTMS) has the potential to be beneficial for recovery. However, the impact of explicit results on the coupling of various rTMS protocols on motor treatment in patients following acute cerebral infarction remain unexplored.

OBJECTIVE

The current study aims to design a sham-controlled randomized report to explore the capability of consecutive suppressive-facilitatory rTMS method to increase the motor results following acute stroke.

METHODS

A hundred ischemic stroke patients suffering from motor disorder were randomly assigned to obtain 4 week sessions of (1)10 Hz over the ipsilesional primary motor cortex (M1) and next 1 Hz over the contralesional M1; (2) contralesional sham stimulation and next ipsilesional real 10 Hz; (3) contralesional real 1 Hz rTMS and next ipsilesional sham stimulation; or (4) bilateral sham-control procedures. At 24 hours before and after the intervention, we obtained cortical excitability data from study subjects. At baseline, after treatment and 3 months follow up, we additionally evaluated patients with the clinical assessments.

RESULTS

At post-intervention, group A showed greater motor improvements in FMA, FMA-UL, NIHSS, ADL and mRS values than group B, group C and group D, that were continued for at least 3 months after the completion of the treatment time. Specifically, it is shown in the cortical excitability study that the motor-evoked potential (MEP) amplitude and resting motor threshold (rMT) more significantly improved in group A than other groups. The improvement in motor function and change in motor cortex excitability exhibit a significant correlation in the affected hemisphere. The combined 1 Hz and 10 Hz stimulation treatment showed a synergistic effect.

CONCLUSIONS

Facilitatory rTMS and coupling inhibitory produced extra satisfactory results in facilitating the motor's recovery in the subacute and acute phase following stroke compared to that acquired from alone single-course modulation.

Theta burst stimulation over the prefrontal cortex: Effects on cerebral oximetry and cardiovascular measures in healthy humans

Theta Burst Stimulation (TBS) is a non-invasive neurophysiological technique, able to induce changes in synaptic activity. Research suggests that TBS may induce changes in cerebral oxygenation, cerebral blood flow, blood pressure and heart rate but there are conflicting results across studies. Thus, the objective of our sham-controlled study is to evaluate if TBS applied to the dorsolateral prefrontal cortex (DLPFC) of healthy volunteers produces changes in cerebral oximetry, heart rate and blood pressure. Forty-nine volunteers of both sexes were randomly allocated to one of five stimulation groups. Before and after real TBS or sham stimulation, blood pressure, heart rate, and cerebral oxygenation of the volunteers were measured. Cerebral oxygenation values were obtained with a near infra-red spectroscopy system. We found a significant reduction in left cortex oximetry after continuous TBS (cTBS) over the left DLPFC (p = 0.039) and a non-significant reduction in right cortex oximetry (p = 0.052). Right hemisphere inhibition (using cTBS) seemed to originate a significant reduction of 8 mmHg in systolic arterial pressure. No other changes were seen in oximetry, cardiac frequency and diastolic arterial pressure. In our group of normal subjects, cTBS applied to the left DLPFC was able to reduce oxygenation in the left cortex. Right hemisphere inhibition was associated with a significant reduction in systolic pressure.

Low-Frequency Repetitive Transcranial Magnetic Stimulation Over Contralesional Motor Cortex for Motor Recovery in Subacute Ischemic Stroke: A Randomized Sham-Controlled Trial

BACKGROUND

Low-frequency repetitive transcranial magnetic stimulation (rTMS) over the contralesional motor cortex (M1) has demonstrated beneficial effects on motor recovery, but evidence among patients with subacute stroke is lacking. We aimed to investigate whether 1-Hz rTMS over the contralesional M1 versus sham rTMS could improve arm function in patients with subacute ischemic stroke when combined with rehabilitative motor training.

METHODS

In total, 77 patients who were within 90 days after their first-ever ischemic stroke were enrolled and randomly allocated to either real (n = 40) or sham rTMS (n = 37). We delivered 1-Hz 30-minute active or sham rTMS before each daily 30-minute occupational therapy sessions over a 2-week period. The primary endpoint was changes in the Box and Block Test (BBT) score immediately after the end of treatment (EOT). Secondary analyses assessed changes in Fugl-Meyer assessment, Finger Tapping Test (FTT), Brunnstrom stage, and grip strength.

CLINICAL TRIAL REGISTRATION

ClinialTrials.gov (NCT02082015).

RESULTS

Changes in BBT immediately after the end of treatment did not differ significantly between the 2 groups (P = .267). Subgroup analysis according to cortical involvement revealed that real rTMS resulted in improvements in BBT at 1 month after EOT (17.4 ± 9.8 real vs 10.9 ± 10.3 sham; P = .023) and Brunnstrom stage of the hand immediately after EOT (0.6 ± 0.5 real vs 0.2 ± 0.5 sham; P = .023), only in the group without cortical involvement.

CONCLUSION

The effects of real and sham rTMS did not differ significantly among patients within 3 months poststroke. The location of stroke lesions should be considered for future clinical trials.

Effects of combining high- and low-frequency repetitive transcranial magnetic stimulation on upper limb hemiparesis in the early phase of stroke

BACKGROUND

Both high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) and low-frequency rTMS (LF-rTMS) are reported to benefit upper limb motor function rehabilitation in patients with stroke. However, the efficacy of combining LF- and HF-rTMS (LF-HF rTMS) has not been adequately explored, especially in the early phase of stroke.

OBJECTIVE

To compare the effects of LF- and LF-HF rTMS on the upper limb motor function in the early phase post stroke.

METHODS

Sixty-two patients were randomly assigned to three groups: LF-rTMS group (1 Hz rTMS to the contralesional hemisphere), LF-HF rTMS group (1 Hz rTMS to the contralesional hemisphere followed by 10 Hz rTMS to the lesional hemisphere) and sham group. The patients received the same conventional rehabilitation accompanied with sessions of rTMS for 15 consecutive days. The upper limb motor function was evaluated using the Fugl-Meyer Assessment (FMA) and the Wolf Motor Function Test (WMFT) before the first session, after the last session, and at 3 months after the last session.

RESULTS

All patients finished the study without any adverse reaction. Three groups exhibited improvement in terms of the FMA score and the log WMFT time at the end of the treatment and 3 months later. Better improvement was found in the LF-HF rTMS group than in the LF-rTMS and sham groups.

CONCLUSION

The results indicated that both LF- and LF-HF rTMS were effective in promoting upper limb motor recovery in patients with acute stroke. Combining HF- and LF-rTMS protocol in the present study is tolerable and more beneficial for motor improvement than the unilateral use of LF-rTMS alone.

Excitatory Repetitive Transcranial Magnetic Stimulation Induces Contralesional Cortico-Cerebellar Pathways After Acute Ischemic Stroke: A Preliminary DTI Study

Background: Repetitive transcranial magnetic stimulation (rTMS) is proved to be effective in facilitating stroke recovery. However, its therapeutic mechanism remains unclear. The present study aimed to investigate changes in white matter fractional anisotropy (FA) after excitatory rTMS to better understand its role in motor rehabilitation.

Materials and Methods: Acute stroke patients with unilateral subcortical infarction in the middle cerebral artery territory were recruited. The patients were randomly divided into an rTMS treatment group and a sham group. The treatment group received a 10-day 5 HZ rTMS applied over the ipsilesional primary motor area beginning at about 4 days after stroke onset. The sham group received sham rTMS. Diffusion tensor imaging (DTI) data were collected in every patient before and after the rTMS or sham rTMS. Voxel-based analysis was used to study the difference in FA between the two groups. The trial of this article has been registered on the ClinicalTrials.gov and the identifier is NCT03163758.

Results: Before the rTMS, there is no significant difference in FA between the two groups. Differently, after the treatment, the rTMS group showed increased FA in the contralesional corticospinal tract, the pontine crossing tract, the middle cerebellar peduncle, the contralesional superior cerebellar peduncle, the contralesional medial lemniscus, and the ipsilesional inferior cerebellar peduncle. These fasciculi comprise the cortex-pontine-cerebellum-cortex loop. Increased FA was also found in the body of corpus callosum and the contralesional cingulum of the treatment group compared with the sham.

Conclusion: The greater connectivity of contralesional cortico-cerebellar loop and the strengthening of interhemispheric connection may reflect contralesional compensation facilitated by the excitatory rTMS, which gives us a clue to understand the therapeutic mechanism of rTMS.