Posts Tagged motor evoked potentials

[Abstract] Modulation of Cerebellar Cortical Plasticity Using Low-Intensity Focused Ultrasound for Poststroke Sensorimotor Function Recovery

Background. Stroke affects widespread brain regions through interhemispheric connections by influencing bilateral motor activity. Several noninvasive brain stimulation techniques have proved their capacity to compensate the functional loss by manipulating the neural activity of alternative pathways. Over the past few decades, brain stimulation therapies have been tailored within the theoretical framework of modulation of cortical excitability to enhance adaptive plasticity after stroke.

Objective. However, considering the vast difference between animal and human cerebral cortical structures, it is important to approach specific neuronal target starting from the higher order brain structure for human translation. The present study focuses on stimulating the lateral cerebellar nucleus (LCN), which sends major cerebellar output to extensive cortical regions.

Methods. In this study, in vivo stroke mouse LCN was exposed to low-intensity focused ultrasound (LIFU). After the LIFU exposure, animals underwent 4 weeks of rehabilitative training.

Results. During the cerebellar LIFU session, motor-evoked potentials (MEPs) were generated in both forelimbs accompanying excitatory sonication parameter. LCN stimulation group on day 1 after stroke significantly enhanced sensorimotor recovery compared with the group without stimulation. The recovery has maintained for a 4-week period in 2 behavior tests. Furthermore, we observed a significantly decreased level of brain edema and tissue swelling in the affected hemisphere 3 days after the stroke.

Conclusions. This study provides the first evidence showing that LIFU-induced cerebellar modulation could be an important strategy for poststroke recovery. A longer follow-up study is, however, necessary in order to fully confirm the effects of LIFU on poststroke recovery.

via Modulation of Cerebellar Cortical Plasticity Using Low-Intensity Focused Ultrasound for Poststroke Sensorimotor Function Recovery – Hongchae Baek, Ki Joo Pahk, Min-Ju Kim, Inchan Youn, Hyungmin Kim, 2018

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[ARTICLE] Comparing the Effects of Functional Electrical Stimulation Versus Somatosensory Stimulation on Increasing Corticospinal Excitability for a Muscle of the Hand – Full Text PDF

Abstract

The electrically-evoked afferent volley generated during NeuroMuscular Electrical Stimulation (NMES) can increase the excitability of CorticoSpinal (CS) pathways. Over time, NMES can strengthen damaged CS pathways and result in enduring improvements in function for persons with central nervous system injury or disease. NMES-induced increases in CS excitability have been studied using a variety of NMES parameters, yet the influence of these stimulation parameters on increasing CS excitability is not well understood.

NMES is commonly delivered at intensities sufficient to generate repeated functional contractions for relatively short durations (30-40 min) or at low intensities, near motor threshold, for long durations (2 h).

For the purpose of this study, these different stimulation protocols are termed Functional Electrical Stimulation (FES) and Somatosensory Stimulation (SS), respectively. A direct comparison of increases in CS excitability induced by such protocols has not been conducted. Thus, the present experiments were designed to compare changes in CS excitability for Abductor Pollicis Brevis (APB) in the hand following FES and SS of the median nerve.

We hypothesized that due to the generation of a larger afferent volley, the FES would increase CS excitability more than the SS. Ten Motor Evoked Potentials (MEPs) were evoked in APB using transcranial magnetic stimulation before and after each type of NMES. MEP amplitude increased significantly following both the FES (by 66 ± 7%, mean ± standard error) and SS (49 ± 6%), but the amplitude of these increases was not significantly different.

These results suggest that just 40 min of FES can increase CS excitability, and potentially provide rehabilitative benefits, to the same extent as 2 h of SS.

Full Text PDF

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[ARTICLE] Safety and Feasibility of Transcranial Direct Current Stimulation in Pediatric Hemiparesis: A Randomized Controlled Pilot Study

Abstract

Background: Transcranial Direct Current Stimulation (tDCS) is a form of non-invasive brain stimulation with improved adult stroke outcomes. Applying tDCS in children with congenital Transcranial Direct Current Stimulation has not yet been explored.

Objective/Design: Primary objective was to explore the safety and feasibility of single-session tDCS through an adverse events profile and symptom assessment within a double-blind, randomized placebo-controlled pilot study in children with congenital hemiparesis. A secondary objective assessed stability of hand and cognitive function.

Participants: Thirteen children, ages 7-18 years, with congenital hemiparesis.

Intervention: Random assignment to a tDCS intervention or tDCScontrol group, with safety and functional assessments on pretest, posttest on the same day and a one-week follow up session. An intervention of 10 minutes of 0.7 mA tDCS was applied to bilateral primary motor cortices. The tDCS intervention was considered safe, if there was no individual decline of 25% or group decline of 2 standard deviations (2 SD) for motor evoked potentials (MEPs), behavioral data, and report of adverse events.

Results: No major adverse events were found, including seizure. Two participants did not complete the study due to lack of MEP and discomfort. For the remaining 11 completed participants, group differences in MEPs and behavioral data did not exceed 2 SD.

Study completed without need for stopping per medical monitor and biostatisticial analysis.

Limitations: Small sample size with data available for 11 participants.

Conclusions: Based on our study, tDCS appears to be safe and feasible and well tolerated in most children with hemiparesis. Future investigation of serial sessions of tDCS in conjunction with rehabilitation in pediatric hemiparesis are indicated to explore the benefit of a synergistic approach to improving hand function.

via Safety and Feasibility of Transcranial Direct Current Stimulation in Pediatric Hemiparesis: A Randomized Controlled Pilot Study.

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