Effect of Transcranial Direct Current Stimulation on Patients With Disorders of Consciousness: A Systematic Review and Meta-analysis

Cognitive and neurophysiological effects of bilateral tDCS neuromodulation in patients with minimally conscious state

The minimally conscious state (MCS) is a clinical condition characterized by severely reduced but present awareness of self and the environment. Transcranial direct current stimulation (tDCS) has shown promising potential. The aim of this quasi-randomised control study was to investigate the effects of bilateral of tDCS applied to the right and left dorsolateral prefrontal cortex (DLPFC) on neurophysiological and cognitive outcomes in 28 patients with MCS. Participants were quasi-randomly assigned to one of two groups: experimental group with tDCS over both DLPFC, and a control group, which received sham tDCS. Neurophysiological assessments included event-related potentials (ERPs) analysis (N200 and P300) and EEG beta band study. Clinical outcomes were measured using ad hoc psychometric battery, including Coma Recovery Scale-Revised (CRS-R), Levels of Cognitive Functioning Scale (LCFS), and Functional Independence Measure (FIM). The findings revealed a significant improvement in ERP latencies and increased beta band rhythms in the experimental group, indicating enhanced neural responsiveness to cognitive stimuli. Additionally, significant improvements were observed in clinical measures of awareness and functional capacity. These findings suggest that tDCS may represent a promising therapeutic option for enhancing both neurophysiological responses and cognitive functioning in patients with MCS.

The efficacy and safety of bilateral synchronous transcutaneous auricular vagus nerve stimulation for prolonged disorders of consciousness: a multicenter, double-blind, stratified, randomized controlled trial protocol

Background

Treatment of disorders of consciousness (DOC) poses a huge challenge for clinical medicine. Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation method, which shows potential in improving recovery of DOC. However, the evidence came from single-center, small-sample randomized controlled trial, which is insufficient to form a conclusion. Thereby, we propose a prospective, multicenter, double-blind, stratified, two-arm randomized controlled trial protocol to investigate the efficacy and safety of bilateral synchronous taVNS for treatment of DOC.

Methods

We aim to recruit 382 patients with prolonged DOC, and divide them into an active stimulation group and a sham stimulation group. The patients in the active stimulation group will receive bilateral synchronous taVNS with a 200 μs pulse width, 20 Hz frequency, and personal adjusted intensity. The sham stimulation group will wear the same stimulator but without current output. Both groups will receive treatment for 30 min per session, twice per day, 6 days per week lasting for 4 weeks. The clinical assessment including Coma Recovery Scale-Revised (CRS-R), Full Outline of Unresponsiveness (FOUR), Glasgow Coma Scale (GCS), and Extended Glasgow Outcome Scale (GOS-E) will be conducted to evaluate its efficacy. Heart rate variability (HRV), blood pressure, and adverse events will be recorded to evaluate its safety.

Discussion

These results will enable us to investigate the efficacy and safety of taVNS for DOC. This protocol will provide multicenter, large-sample, high-quality Class II evidence to support bilateral synchronous taVNS for DOC, and will advance the field of treatment options for DOC.Clinical trial registration:https://www.chictr.org.cn/showproj.html?proj=221851, ChiCTR2400081978.

Transcranial direct current stimulation promotes angiogenesis and improves neurological function via the OXA-TF-AKT/ERK signaling pathway in traumatic brain injury

Traumatic brain injury (TBI) and its resulting complications pose a major challenge to global public health, resulting in increased rates of disability and mortality. Cerebrovascular dysfunction is nearly universal in TBI cases and is closely associated with secondary injury after TBI. Transcranial direct current stimulation (tDCS) shows great potential in the treatment of TBI; however, the exact mechanism remains elusive. In this study, we performed in vivo and in vitro experiments to explore the effects and mechanisms of tDCS in a controlled cortical impact (CCI) rat model simulating TBI. In vivo experiments show that tDCS can effectively reduce brain tissue damage, cerebral edema and neurological deficits. The potential mechanism may be that tDCS improves the neurological function of rats by increasing orexin A (OXA) secretion, upregulating the TF-AKT/ERK signaling pathway, and promoting angiogenesis at the injury site. Cellular experiments showed that OXA promoted HUVEC migration and angiogenesis, and these effects were counteracted by the ERK1/2 inhibitor LY3214996. The results of Matrigel experiment in vivo showed that TNF-a significantly reduced the ability of HUVEC to form blood vessels, but OXA could rescue the effect of TNF-a on the ability of HUVEC to form blood vessels. However, LY3214996 could inhibit the therapeutic effect of OXA. In summary, our preliminary study demonstrates that tDCS can induce angiogenesis through the OXA-TF-AKT/ERK signaling pathway, thereby improving neurological function in rats with TBI.