Narrative Review of Noninvasive Brain Stimulation in Stroke Rehabilitation

Effects of home-based neurostimulation on outcomes after stroke: a systematic review and meta-analysis

BACKGROUND

Home-based rehabilitation is a cost-effective means of making services available for patients. The aim of this study is to determine the evidence in the literature on the effects of home-based neurostimulation in patients with stroke.

METHOD

We searched PubMED, Embase, Web of Science, Scopus, and CENTRAL for randomized controlled trials on the subject matter using keywords such as stroke, electrical stimulation and transcranial direct current stimulation. Information on participants' characteristics and mean scores on the outcomes of interest were extracted. Risks of bias and methodological quality of the included studies were assessed using Cochrane Risks of bias tool and PEDro scale respectively. The data was analyzed using both narrative and quantitative syntheses. In the quantitative synthesis, meta-analysis was carried out using random effect model analysis.

RESULT

The results showed that, home-based neurostimulation is superior to the control at improving upper limb muscle strength (SMD = 0.72, 95% CI = 0.08 to 1.32, p = 0.03), functional mobility (SMD = -0.39, 95% CI = -0.65 to 0.14, p = 0.003) and walking endurance (SMD = 0.33, 95% CI = 0.08 to 0.59, p = 0.01) post intervention; and upper limb motor function (SMD = 0.9, 95% CI = 0.10 to 1.70, p = 0.03), functional mobility (SMD = -0.30, 95% CI = -0.56 to -0.05, p = 0.02) and walking endurance (SMD = 0.33, 95% CI = 0.08 to 0.59, p = 0.01) at follow-up.

CONCLUSIONS

Home-based neurostimulation can be used to improve upper and lower limb function after stroke.

Advanced rehabilitation in ischaemic stroke research

At present, due to the rapid progress of treatment technology in the acute phase of ischaemic stroke, the mortality of patients has been greatly reduced but the number of disabled survivors is increasing, and most of them are elderly patients. Physicians and rehabilitation therapists pay attention to develop all kinds of therapist techniques including physical therapy techniques, robot-assisted technology and artificial intelligence technology, and study the molecular, cellular or synergistic mechanisms of rehabilitation therapies to promote the effect of rehabilitation therapy. Here, we discussed different animal and in vitro models of ischaemic stroke for rehabilitation studies; the compound concept and technology of neurological rehabilitation; all kinds of biological mechanisms of physical therapy; the significance, assessment and efficacy of neurological rehabilitation; the application of brain-computer interface, rehabilitation robotic and non-invasive brain stimulation technology in stroke rehabilitation.

Comparative efficacy of different noninvasive brain stimulation protocols on upper-extremity motor function and activities of daily living after stroke: a systematic review and network meta-analysis

The objectives of the study were to systematically evaluate the rehabilitation effect of noninvasive brain stimulation (NIBS) on upper extremity motor function and activities of daily living in stroke patients and to prioritize various stimulation protocols for reliable evidence-based medical recommendations in patients with upper extremity motor dysfunction after stroke. Web of Science, PubMed, Embase, Cochrane Library, CNKI, Wanfang, VIP, and CBM were searched to collect all randomized controlled trials (RCTs) of NIBS to improve upper extremity motor function in stroke patients. The retrieval time was from the establishment of all databases to May 2023. According to the Cochrane system evaluation manual, the quality of the included studies was evaluated, and the data were extracted. Statistical analysis was carried out by using RevMan 5.3, R 4.3.0, and Stata 17.0 software. Finally, 94 RCTs were included, with a total of 5546 patients. Meta-analysis showed that NIBS improved the Fugl-Meyer assessment (FMA) score (mean difference (MD) = 6.51, 95% CI 6.20 ~ 6.82, P < 0.05), MBI score (MD = 7.69, 95% CI 6.57 ~ 8.81, P < 0.05), ARAT score (MD = 5.06, 95% CI 3.85 ~ 6.27, P < 0.05), and motor evoked potential (MEP) amplitude. The modified Ashworth scale score (MD =  - 0.37, 95% CI - 0.60 to - 0.14, P < 0.05), National Institutes of Health Stroke Scale score (MD =  - 2.17, 95% CI - 3.32 to - 1.11, P < 0.05), incubation period of MEP (MD =  - 0.72, 95% CI - 1.06 to - 0.38, P < 0.05), and central motor conduction time (MD =  - 0.90, 95% CI - 1.29 to - 0.50, P < 0.05) were decreased in stroke patients. Network meta-analysis showed that the order of interventions in improving FMA scores from high to low was anodal-transcranial direct current stimulation (tDCS) (surface under the cumulative ranking curve (SUCRA) = 83.7%) > cathodal-tDCS (SUCRA = 80.2%) > high-frequency (HF)-repetitive transcranial magnetic stimulation (rTMS) (SUCRA = 68.5%) > low-frequency (LF)-rTMS (SUCRA = 66.5%) > continuous theta burst stimulation (cTBS) (SUCRA = 54.2%) > bilateral-tDCS (SUCRA = 45.2%) > intermittent theta burst stimulation (iTBS) (SUCRA = 34.1%) > sham-NIBS (SUCRA = 16.0%) > CR (SUCRA = 1.6%). In terms of improving MBI scores, the order from high to low was anodal-tDCS (SUCRA = 88.7%) > cathodal-tDCS (SUCRA = 85.4%) > HF-rTMS (SUCRA = 63.4%) > bilateral-tDCS (SUCRA = 56.0%) > LF-rTMS (SUCRA = 54.2%) > iTBS (SUCRA = 32.4%) > sham-NIBS (SUCRA = 13.8%) > CR (SUCRA = 6.1%). NIBS can effectively improve upper extremity motor function and activities of daily living after stroke. Among the various NIBS protocols, anodal-tDCS demonstrated the most significant intervention effect, followed by cathodal-tDCS and HF-rTMS.

Effects of transcranial direct current stimulation of the left primary motor cortex area on hand grip strength and dexterity in healthy individuals: A double-blind randomized sham-controlled trial

BACKGROUND AND OBJECTIVE

Motor function plays a critical role in everyday activities, from basic self-care tasks to complex activities that require precision and dexterity. This study was conducted to investigate the effects of transcranial direct current stimulation (tDCS) on grip strength and hand dexterity in healthy individuals.

METHOD

We conducted a double-blind randomized clinical trial with two groups of sham and active tDCS. The anode was fixed over the primary motor cortex area M1 on the C3 point. The primary outcome was hand grip strength measured by a dynamometer and the secondary outcomes were hand dexterity and assembly assessed by the Purdue Pegboard test. The tDCS program was administered at rest three and two times for the first and second week for a total of five sessions of 20 min each.

RESULTS

There was no significant improvement in the mean difference in grip strength between the sham (N = 27) and active (N = 27) tDCS groups (1.7 vs. 2.3, Mann-Whitney U test, P = 0.869, d = 0.02). Participants who received active tDCS showed subtle improvements in right-hand dexterity (0.6 vs. 1.3, U test P = 0.017, d = 0.33) and overall manual dexterity (1.4 vs. 3.2, U test P = 0.023, d = 0.31) compared with the sham group. Other comparisons for hand dexterity and assembly (motor coordination and fine skills during the manipulation of small objects) between the two groups were not significant. We did not find any adverse effects of sham or active tDCS.

CONCLUSION

Our study showed a potential for clinical improvement in hand dexterity after five sessions of tDCS in healthy individuals.

Neuropsychological and Anatomical-Functional Effects of Transcranial Magnetic Stimulation in Post-Stroke Patients with Cognitive Impairment and Aphasia: A Systematic Review

Transcranial magnetic stimulation (TMS) has been found to be promising in the neurorehabilitation of post-stroke patients. Aphasia and cognitive impairment (CI) are prevalent post-stroke; however, there is still a lack of consensus about the characteristics of interventions based on TMS and its neuropsychological and anatomical-functional benefits. Therefore, studies that contribute to creating TMS protocols for these neurological conditions are necessary. To analyze the evidence of the neuropsychological and anatomical-functional TMS effects in post-stroke patients with CI and aphasia and determine the characteristics of the most used TMS in research practice. The present study followed the PRISMA guidelines and included articles from PubMed, Scopus, Web of Science, ScienceDirect, and EMBASE databases, published between January 2010 and March 2023. In the 15 articles reviewed, it was found that attention, memory, executive function, language comprehension, naming, and verbal fluency (semantic and phonological) are the neuropsychological domains that improved post-TMS. Moreover, TMS in aphasia and post-stroke CI contribute to greater frontal activation (in the inferior frontal gyrus, pars triangularis, and opercularis). Temporoparietal effects were also found. The observed effects occur when TMS is implemented in repetitive modality, at a frequency of 1 Hz, in sessions of 30 min, and that last more than 2 weeks in duration. The use of TMS contributes to the neurorehabilitation process in post-stroke patients with CI and aphasia. However, it is still necessary to standardize future intervention protocols based on accurate TMS characteristics.

Deciphering Post-Stroke Sleep Disorders: Unveiling Neurological Mechanisms in the Realm of Brain Science

Sleep disorders are the most widespread mental disorders after stroke and hurt survivors' functional prognosis, response to restoration, and quality of life. This review will address an overview of the progress of research on the biological mechanisms associated with stroke-complicating sleep disorders. Extensive research has investigated the negative impact of stroke on sleep. However, a bidirectional association between sleep disorders and stroke exists; while stroke elevates the risk of sleep disorders, these disorders also independently contribute as a risk factor for stroke. This review aims to elucidate the mechanisms of stroke-induced sleep disorders. Possible influences were examined, including functional changes in brain regions, cerebrovascular hemodynamics, neurological deficits, sleep ion regulation, neurotransmitters, and inflammation. The results provide valuable insights into the mechanisms of stroke complicating sleep disorders.

The effect of transcranial alternating current stimulation on functional recovery in patients with stroke: a narrative review

Stroke is a common neurological disorder worldwide that can cause significant disabilities. Transcranial alternating current stimulation (tACS) is an emerging non-invasive neuromodulation technique that regulates brain oscillations and reshapes brain rhythms. This study aimed to investigate the effect of tACS on functional recovery in patients with stroke. The MEDLINE (PubMed), Cochrane Library, Embase, SCOPUS, and Web of Science databases were searched for English-language articles on tACS and stroke, published up to October 20, 2023. The following key search phrases were combined to identify potentially relevant articles: 'tACS,' 'transcranial alternating current stimulation,' 'stroke,' 'cerebral infarct,' and 'intracerebral hemorrhage.' The inclusion criteria for study selection were as follows: (1) studies involving patients with stroke and (2) studies that used tACS for functional recovery. A total of 34 potentially relevant studies were identified. Five articles were included in this review after reading the titles and abstracts and assessing their eligibility based on the full-text articles. Among the included studies, one investigated the improvement in overall functional status in patients with stroke after tACS, and two investigated the effect of tACS on motor function and gait patterns. Moreover, one study reported the efficacy of tACS on aphasia recovery, and one study evaluated the effect of tACS on hemispatial neglect. Our findings suggest that tACS improves functional recovery in patients with stroke. The application of tACS was associated with improved overall functional recovery, sensorimotor impairment, aphasia, and hemispatial neglect. The potential clinical application of tACS should be supported by high-quality, evidence-based studies.

New approaches to recovery after stroke

After a stroke, several mechanisms of neural plasticity can be activated, which may lead to significant recovery. Rehabilitation therapies aim to restore surviving tissue over time and reorganize neural connections. With more patients surviving stroke with varying degrees of neurological impairment, new technologies have emerged as a promising option for better functional outcomes. This review explores restorative therapies based on brain-computer interfaces, robot-assisted and virtual reality, brain stimulation, and cell therapies. Brain-computer interfaces allow for the translation of brain signals into motor patterns. Robot-assisted and virtual reality therapies provide interactive interfaces that simulate real-life situations and physical support to compensate for lost motor function. Brain stimulation can modify the electrical activity of neurons in the affected cortex. Cell therapy may promote regeneration in damaged brain tissue. Taken together, these new approaches could substantially benefit specific deficits such as arm-motor control and cognitive impairment after stroke, and even the chronic phase of recovery, where traditional rehabilitation methods may be limited, and the window for repair is narrow.

The assessment of interhemispheric imbalance using functional near-infrared spectroscopic and transcranial magnetic stimulation for predicting motor outcome after stroke

Objective

To investigate changes in interhemispheric imbalance of cortical excitability during motor recovery after stroke and to clarify the relationship between motor function recovery and alterations in interhemispheric imbalance, with the aim to establish more effective neuromodulation strategies.

Methods

Thirty-one patients underwent assessments of resting motor threshold (RMT) using transcranial magnetic stimulation (TMS); the cortical activity of the primary motor cortex (M1), premotor cortex (PMC), and supplementary motor area (SMA) using functional near-infrared spectroscopy (fNIRS); as well as motor function using upper extremity Fugl-Meyer (FMA-UE). The laterality index (LI) of RMT and fNIRS were also calculated. All indicators were measured at baseline(T1) and 1 month later(T2). Correlations between motor function outcome and TMS and fNIRS metrics at baseline were analyzed using bivariate correlation.

Results

All the motor function (FMA-UE1, FMA-UE2, FMA-d2) and LI-RMT (LI-RMT1 and LI-RMT2) had a moderate negative correlation. The higher the corticospinal excitability of the affected hemisphere, the better the motor outcome of the upper extremity, especially in the distal upper extremity (r = -0.366, p = 0.043; r = -0.393, p = 0.029). The greater the activation of the SMA of the unaffected hemisphere, the better the motor outcome, especially in the distal upper extremity (r = -0.356, p = 0.049; r = -0.367, p = 0.042). There was a significant moderate positive correlation observed between LI-RMT2 and LI-SMA1 (r = 0.422, p = 0.018). The improvement in motor function was most significant when both LI-RMT1 and LI-SMA1 were lower. Besides, in patients dominated by unaffected hemisphere corticospinal excitability during motor recovery, LI-(M1 + SMA + PMC)2 exhibited a significant moderate positive association with the proximal upper extremity function 1 month later (r = 0.642, p = 0.007).

Conclusion

The combination of both TMS and fNIRS can infer the prognosis of motor function to some extent. Which can infer the role of both hemispheres in recovery and may contribute to the development of effective individualized neuromodulation strategies.

Somatosensory Impairment and Chronic Pain Following Stroke: An Observational Study

BACKGROUND

Chronic pain and somatosensory impairment are common following a stroke. It is possible that an interaction exists between pain and somatosensory impairment and that a change in one may influence the other. We therefore investigated the presence of chronic pain and self-reported altered somatosensory ability in individuals with stroke, aiming to determine if chronic pain is more common in stroke survivors with somatosensory impairment than in those without.

METHODS

Stroke survivors were invited to complete an online survey that included demographics, details of the stroke, presence of chronic pain, and any perceived changes in body sensations post-stroke.

RESULTS

Survivors of stroke (n = 489) completed the survey with 308 indicating that they experienced chronic pain and 368 reporting perceived changes in somatosensory function. Individuals with strokes who reported altered somatosensory ability were more likely to experience chronic pain than those who did not (OR = 1.697; 95% CI 1.585, 2.446). Further, this difference was observed for all categories of sensory function that were surveyed (detection of light touch, body position, discrimination of surfaces and temperature, and haptic object recognition).

CONCLUSIONS

The results point to a new characteristic of chronic pain in strokes, regardless of nature or region of the pain experienced, and raises the potential of somatosensory impairment being a rehabilitation target to improve pain-related outcomes for stroke survivors.