Motor Cortex Neurostimulation Technologies for Chronic Post-stroke Pain: Implications of Tissue Damage on Stimulation Currents

Abstract

Background: Central post stroke pain (CPSP) is a highly refractory syndrome that can occur after stroke. Primary motor cortex (M1) brain stimulation using epidural brain stimulation (EBS), transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS) have been explored as potential therapies for CPSP. These techniques have demonstrated variable clinical efficacy. It is hypothesized that changes in the stimulating currents that are caused by stroke-induced changes in brain tissue conductivity limit the efficacy of these techniques.Methods: We generated MRI-guided finite element models of the current density distributions in the human head and brain with and without chronic focal cortical infarctions during EBS, TMS, and tDCS. We studied the change in the stimulating current density distributions’ magnitude, orientation, and maxima locations between the different models.Results: Changes in electrical properties at stroke boundaries altered the distribution of stimulation currents in magnitude, location, and orientation. Current density magnitude alterations were larger for the non-invasive techniques (i.e., tDCS and TMS) than for EBS. Nonetheless, the lesion also altered currents during EBS. The spatial shift of peak current density, relative to the size of the stimulation source, was largest for EBS.Conclusion: In order to maximize therapeutic efficiency, neurostimulation trials need to account for the impact of anatomically disrupted neural tissues on the location, orientation, and magnitude of exogenously applied currents. The relative current-neuronal structure should be considered when planning stimulation treatment, especially across techniques (e.g., using TMS to predict EBS response). We postulate that the effects of altered tissue properties in stroke regions may impact stimulation induced analgesic effects and/or lead to highly variable outcomes during brain stimulation treatments in CPSP.

Pain modulation effect on motor cortex after optogenetic stimulation in shPKCγ knockdown dorsal root ganglion-compressed Sprague-Dawley rat model

“…62,63 This focus on M1 neuromodulation will be helpful for focusing on other fundamental studies in different types of pain. [64][65][66][67][68] We used optogenetics technology to stimulate M1 for producing circuit-specific neuromodulation to regulate neuronal activities by overexpressing light-sensitive proteins (opsins) in M1 layer 5 cells. 60 Optogenetic stimulation was accomplished by using viral vectors that infect only definite neuron types through cell type-specific promoter CaMKIIa, which will localize optogenetic proteins to excitatory neurons.…”

Motor cortex stimulation in deafferentation facial pain

“…[24] Согласно результатам современных исследований, эффект стимуляции мозга зависит от электромагнитных свойств ткани, которая по-разному реагирует на разные методы стимуляции. Вероятно, этот факт требует точного размещения стимулирующего электрода для достижения наибольшей терапевтической эффективности [24,27,28]. A. O'Brien и соавт.…”

“…A. O'Brien и соавт. [27] подчеркнули необходимость уточнять топографию измененной вследствие инсульта ткани мозга у пациентов с центральной постинсультной болью. Изменения анатомии и скопление ликвора могут влиять на расположение, ориентацию и величину действующего тока вблизи границы поражения.…”

“…Некоторые авторы отмечают повышенный риск инфекционных осложнений во время тестового периода, который проводится после краниотомии и установки тестовых электродов в эпидуральное пространство и длится до 5-7 дней. По данным литературы [27,[29][30][31], инфекционные осложнения при MCS могут составлять 2,2-5,7%, их частота может быть выше в тестовом периоде (до 22%), поэтому некоторые авторы предлагают имплантировать систему сразу без тестового испытания. Согласно данным A. Raslan и соавт.…”

Quantitative proteomic analysis of dermal papilla from male androgenetic alopecia comparing before and after treatment with low‐level laser therapy

“…LLLT is evidenced to enhance wound repair, and promote fibroblast migration, collagen deposition, and neovascularization [14,15]. Until now, there are 2 ex vivo [16], 8 animal [17][18][19][20][21], and 12 published clinical studies [19,[22][23][24][25][26][27][28][29] evaluating the effects of LLLT especially in the red and blue light spectrum [28] on hair loss. Of the 13 clinical studies, 11 of them investigate the efficacy of the LLLT devices (comb, helmet, and cap) on male and female AGA and two of them do studies on alopecia areata (AA).…”