Harnessing theta waves: tACS as a breakthrough in alleviating post-stroke chronic pain

 Will your competent? doctor do anything with this?

Here's how long your doctor has been incompetent in not having protocols to prevent this problem. Which means your board of directors is incompetent in not having correct goals for the stroke medical 'professionals'!

39% to 55% post stroke pain (3 posts to October 2022)

The latest here:

Harnessing theta waves: tACS as a breakthrough in alleviating post-stroke chronic pain

Ningjing Song^1,2,3,4Ling Long^1,2,3,4Nianquan Liu^1,2,3,4Yujun Luo^1,2,3,4Meng Wei^1,2,3,4Hai Huang^1,2,3,4*Wan Liu^1,2,3,4*

• ¹Department of Tuina and Rehabilitation Medicine, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, China
• ²Department of Tuina and Rehabilitation Medicine, Affiliated Hospital of Hubei University of Chinese Medicine, Wuhan, China
• ³Hubei Sizhen Laboratory, Wuhan, China
• ⁴First Clinical Medical College, Hubei University of Chinese Medicine, Wuhan, China

Neural oscillations play a critical role in the regulation of brain functions, with theta waves (4–8 Hz) in the sensorimotor cortex significantly influencing pain perception and modulation. These oscillations can modulate pain signal transmission, emotional cognition, and neuroplasticity. Post-stroke chronic pain is a common and complex symptom that imposes significant physiological and psychological burdens on patients. Transcranial alternating current stimulation (tACS), a non-invasive brain stimulation technique, can synchronize specific frequency neural activities, reorganize brain networks, and modulate neuroplasticity by adjusting specific frequency neural oscillations. In recent years, tACS has been widely applied in the research and treatment of various neurological and psychiatric disorders. This study aims to systematically summarize the current research progress on the regulation of θ oscillations in sensorimotor cortex by tACS. By reviewing relevant experimental and clinical studies, we explore the specific mechanisms of θ oscillations in pain perception and modulation and analyze the mechanisms and effects of tACS modulation of θ oscillations. Additionally, we examine the central and peripheral neural mechanisms of post-stroke chronic pain, emphasizing the critical role of the sensorimotor cortex in pain processing. In conclusion, tACS shows potential for modulating sensorimotor cortex θ oscillations and alleviating post-stroke chronic pain. This research provides new insights into the neural modulation mechanisms related to pain and offers potential new directions for developing novel therapies. Future clinical studies and technological optimizations are necessary to ensure the effectiveness and feasibility of tACS in clinical practice.

1 Introduction

Chronic post-stroke pain (PSCP) is a prevalent complication, affecting approximately 12% of individuals who have experienced a stroke (Zhan et al., 2019). The pathogenesis of PSCP is intricate, involving the reorganization and dysfunction of both the central and peripheral nervous systems (Larson et al., 2019). Patients frequently endure severe neuropathic pain, sensory abnormalities, and heightened pain sensitivity. Current therapeutic interventions, including pharmacological treatments, physiotherapy, and cognitive behavioral therapy, often demonstrate limited efficacy, with many patients struggling to achieve sustained pain relief (Haslam et al., 2021). Central nervous system pathological alterations are central to the challenging nature of PSCP, particularly the dysfunction of the sensorimotor cortex, which is closely linked to pain perception. Consequently, the modulation of sensorimotor cortex activity to alleviate pain has emerged as an urgent research priority. Recent advancements in neuroscience have highlighted the significant role of neural electrical activity in pain stimulation and perception (Yin and Zhao, 2024). Consequently, the modulation of sensorimotor cortex activity to alleviate pain has emerged as an urgent research priority.

Recent advancements in neuroscience have highlighted the significant role of neural electrical activity in pain stimulation and perception, emphasizing the importance of neural oscillation energy regulation and phase properties in the onset and modulation of pain. Neural oscillations are integral not only to pain processing but also to a wide range of cognitive and sensory functions. The sensorimotor cortex, a critical region for processing sensory input and motor output (Kong et al., 2024), is particularly influenced by θ-wave (4–8 Hz) neural oscillations (θ oscillations), which are pivotal in sensorimotor integration, attention regulation, and pain modulation. Research indicates that synchronized θ wave activity may enhance the integration of sensory information and the formulation of motor plans by modulating the functional connectivity within the sensorimotor network. Furthermore, θ waves play a distinctive role in pain modulation, particularly in chronic pain conditions, where abnormalities in θ wave patterns may be linked to central sensitization phenomena. Such abnormalities in neural oscillation patterns are posited to be central mechanisms in the development of chronic pain.

Transcranial alternating current stimulation (tACS) is an emerging neuromodulation technique that non-invasively applies specific frequency alternating currents to the scalp to modulate neural oscillations in the brain (Feurra et al., 2011; Wischnewski et al., 2023). Transcranial alternating current stimulation (tACS) presents a promising avenue for the treatment of persistent sensorimotor cortex pain (PSCP) through the modulation of θ oscillations. Although the application of tACS in pain research remains in its nascent stages, ongoing investigations continue to explore its analgesic effects and underlying mechanisms, with a current paucity of direct evidence to definitively elucidate the analgesic mechanism of tACS (Angelakis et al., 2013; May et al., 2021). This study aims to systematically synthesize the existing research on the modulation of θ oscillations in the sensorimotor cortex via tACS, to investigate the specific role of these oscillations in pain perception and modulation, and to analyze the effects and mechanisms of their modulation by tACS. Furthermore, this paper will delve into the mechanisms of tACS intervention in PSCP, with a particular focus on the central and peripheral neural mechanisms involved, highlighting the critical role of the sensorimotor cortex in pain processing. Additionally, the paper will propose future research directions and discuss the clinical application prospects of tACS, with the objective of providing a theoretical foundation and practical references for the treatment of chronic pain using this modality.

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Following a stroke, pain is common but can be managed

 Survivors don't want it managed, they want it cured! So our stroke medical 'professionals' are OK with 3.9 to 5.5 million yearly stroke survivors having uncurable pain. THAT IS COMPLETE INCOMPETENCY!

• 39% to 55% post stroke pain (2 posts to October 2022)

Following a stroke, pain is common but can be managed

By Laura Williamson, American Heart Association News

(SelectStock/Vetta via Getty Images)

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At 51, Kerwin Ifill had a stroke. Though he believed he was in excellent health, a tangle of blood vessels – something called an arteriovenous malformation, or AVM – was hiding in his brain. One day after a regular gym workout, a vessel burst while he was taking a nap.

The brain bleed caused the entire right side of Ifill's body to go numb. Confused, he called for an ambulance. He was shocked to find out that he'd had a stroke and needed brain surgery. But there were more surprises to come.

"After coming out of surgery, I had a crazy burning sensation in my face," he said. "It was almost like alcohol being poured into a wound."

Ten years later, his face still burns – the result of damage to his nerves that can be managed with medication but can't be fixed.

"Post-stroke pain is not uncommon," said Dr. Talya Fleming, Ifill's doctor and the medical director of the Stroke Recovery Program and Aftercare Program at the JFK Johnson Rehabilitation Institute at Hackensack Meridian Health in Edison, New Jersey.

Though just how common it is remains unclear. Researchers disagree on its prevalence, with some estimating between 10% to as many as 70% of stroke survivors experience pain in the weeks and months that follow. Post-stroke pain can range from headaches that resolve on their own to chronic, severe joint pain or burning sensations like the type Ifill experiences.

"Some types of pain are due to the mechanical changes that happen in the body after a stroke, and some are due to nerve irritability from the stroke itself," said Dr. Richard Harvey, a professor of physical medicine and rehabilitation and physical therapy and human movement sciences at Northwestern University Feinberg School of Medicine in Chicago.

"The majority of patients don't have pain, but a good proportion do," he said.

Fleming, who also is a clinical associate professor at Hackensack Meridian School of Medicine and Rutgers Robert Wood Johnson Medical School in New Jersey, said people who have severe strokes can be more likely to experience post-stroke pain, and it's common for people with post-stroke pain to have had a chronic pain condition prior to their stroke. Having a history of depression, smoking and being younger at the time of a stroke have also been associated with a higher risk for post-stroke pain.

In addition to headaches, the most common types of post-stroke pain include shoulder pain; central post-stroke pain; spasticity; and complex regional pain syndrome, a burning sensation and other symptoms which can be related to nerve damage but may also occur with no evidence of direct nerve injury. Despite its impact on everyday life, research suggests post-stroke pain is often underdiagnosed and not well managed.

Persistent shoulder pain affects roughly 20% of stroke survivors as many as four years after their strokes, one study found. It typically occurs within three months of a stroke and can be caused by a variety of factors.

"The shoulder is a very complex joint in the body," Fleming said. "It can move in many directions. We use our arms for so many day-to-day activities, such as eating, dressing and manipulating objects with our hands. If the arm muscles are weak after a stroke, using those muscles can put a strain on the shoulder joint."

"It's not the stroke that causes it, but what happens after," said Harvey, who also is chair of the Brain Innovation Center at the Shirley Ryan AbilityLab, a rehabilitation hospital in Chicago.

Weak muscles from stroke paralysis can lead to poor mechanical glide in the shoulder joint, rotator cuff injuries and inflammation in the joints and tendons, he said. "If not managed well, this can lead to chronic inflammation and a frozen shoulder (scar tissue that forms in the joint). Acute pain will eventually turn into chronic pain."

There are numerous ways to treat shoulder pain that results from a stroke, including medications, exercise therapies, steroid injections to reduce inflammation, and electrical stimulation. Harvey said it's important to get a full diagnostic workup to properly identify the root of the problem.

Central post-stroke pain syndrome occurs when there is damage to the pathway in the brain that transmits signals about pain. For some people, this can cause feelings of extreme pain when they are touched even lightly.

Treatment may include medications for nerve injury or irritation, deep brain stimulation or medications to treat the depression and anxiety this type of pain can cause over the long term.

Kerwin Ifill uses medications and meditation to manage the burning pain in his face caused by a stroke. (Photo courtesy of Kerwin Ifill)

Fleming said lifestyle changes, such as getting adequate sleep, eating a healthy diet and using correct posture can help alleviate central post-stroke pain, but "unfortunately, we don't have a precise solution for this."

Spasticity refers to involuntary muscle reflexes and contractions that may occur following a stroke. This can lead to pain when the movements cause tension around the joints and tendons. While common, Harvey said that in his experience, this type of pain is not usually severe and can be treated with medications.

Complex regional pain syndrome refers to long-lasting pain and inflammation that can occur following a stroke, heart attack or an injury. It can affect any part of the body but typically affects an arm, leg, hand or foot.

Harvey said this type of pain can occur from a lack of mobility. The body parts "become tender, and people don't want to move them," he said. "We don't see it too often anymore because modern stroke care centers now mobilize people early after stroke."

Many types of post-stroke pain are temporary if properly managed, Harvey said.

Any type of pain following a stroke should be addressed by a health care professional such as a primary care doctor or neurologist, or at a stroke rehabilitation center, Fleming said. "You don't have to live with this pain."

Even pain that can't be eliminated can at least be reduced, she said.

Ifill uses meditation and a combination of medications to manage his pain. He's also learned to identify situations and environments that can trigger it.

"When I'm processing information, just one or two things at a time, it's tolerable," he said. "But if there are too many things going on, like if I go to the movies, the sound and lighting and noise can make this hard. It feels like everything is closing in on me and that burning sensation increases."

Rating his pain on a scale of 1 to 10, "the lowest I've been able to get it down to is a 4 or 5," Ifill said. "I've just gotten used to it."

Bibliometric Analysis of Post-Stroke Pain Research Published from 2012 to 2021

 Useless. With 39% to 55% post stroke pain (1 post to October 2022) and known a lot sooner than that(10+ years), the idea is to solve the problem, NOT JUST TELL US IT EXISTS!

Bibliometric Analysis of Post-Stroke Pain Research Published from 2012 to 2021

      

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Authors Xiong F, Shen P, Li Z, Huang Z, Liang Y, Chen X, Li Y , Chai X , Feng Z, Li M

Received 22 May 2022

Accepted for publication 12 December 2022

Published 5 January 2023 Volume 2023:16 Pages 1—20

DOI https://doi.org/10.2147/JPR.S375063

Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr Jonathan Greenberg

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Feng Xiong,¹ Peng Shen,¹ Zhenhui Li,² Ziyi Huang,¹ Ying Liang,¹ Xiwen Chen,¹ Yutong Li,³ Xinping Chai,³ Zhen Feng,^1,* Moyi Li<sup>1,*

1</sup>Rehabilitation Medicine Department, The First Affiliated Hospital of Nanchang University, Nanchang, People’s Republic of China; ²Children Health Care Department, Longyan First Hospital Affiliated to Fujian Medical University, Longyan, People’s Republic of China; ³First School of Clinical Medicine, Nanchang University, Nanchang, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Moyi Li; Zhen Feng, Rehabilitation Medicine Department, The First Affiliated Hospital of Nanchang University, No. 17, Yong Wai Zheng Jie, Nanchang, Jiangxi, 330006, People’s Republic of China, Tel +86 15806031050 ; +86 13970038111, Email limoyi123@aliyun.com; fengzhen@email.ncu.edu.cn

Background and Purpose: Pain is one of the most common symptoms in patients after stroke. It is a distressing experience that affects patients’ quality of life, and it is highly prevalent in clinical practice. The pathogenesis mechanisms of PSP are not so clear, and there is currently a lack of effective medical treatments, hence it is necessary to establish a sufficient understanding of this disease. Limited number of studies have applied bibliometric methods to systematically analyze studies on post-stroke pain. This study aimed to systematically analyze scientific studies conducted worldwide on post-stroke pain from 2012 to 2021 to evaluate global trends in this field using a bibliometric analysis.
Methods: Publications related to post-stroke pain from 2012 to 2021 were obtained from the Web of Science Core Collection database. Bibliometrics Biblioshiny R-package software was used to analyze the relationship of publication year with country, institution, journals, authors, and keywords and to generate variant visual maps to show annual publications, most relevant countries, authors, sources, keywords, and top-cited articles.
Results: In this study, 5484 papers met the inclusion criteria. The annual growth rate of publications was 5.13%. The USA had the highest number of publications (1381, 25.2%) and citations (36,395), and the University of Toronto had the highest number of papers (156, 2.8%). “Stroke”, “management”, “pain”, “risk”, “prevalence”, “ischemic stroke”, “risk factors”, “disease”, “diagnosis” and “therapy” are the top 10 keywords.
Conclusion: The global research interest regarding PSP has maintained growing over the past ten years. Both central post stroke pain and hemiplegic shoulder pain are the hottest research subjects. Further investigations are needed in order to reveal the mystery of the pathophysiologic mechanisms of CPSP, and high-quality well-designed trials of potential treatments of CPSP and HSP are also needed.

Keywords: post-stroke pain, publication trends, bibliometric analysis, research interest

Introduction

Post-stroke pain (PSP) is a common and refractory disabling complication in stroke survivors. The mean prevalence of the various types of post-stroke pain was 29.56%, which was higher in the subacute and chronic stages than in the acute post-stroke stage (14.06% in the acute, 42.73% in the subacute, and 31.90% in the chronic post-stroke stage).^1–3 The most common types of PSP include central post-stroke pain (CPSP), complex regional pain syndrome (CRPS), pain secondary to spasticity, shoulder pain, and headache.^3–5 Currently, the diagnosis of definite neuropathic pain should be based on the sensory findings, relevant lesion, and specific findings on clinical examination, as there are no pathognomonic features of PSP.^6–8 Patients who experience PSP seem to be more likely to have a lower quality of life, poorer cognitive and functional performance, higher fatigue perception, and higher incidence of depression, anxiety symptoms, sleep disorders, and suicidality, facing the dual challenges of physical and mental suffering.^9–15 Both pharmacological and non-pharmacological interventions can be used to relieve PSP.¹⁶ Besides, a multimodal strategy incorporating lifestyle-related interventions have been studied to optimize prognosis with improved quality of life and social participation after stroke, considering the complex interrelation between medical and psychosocial aspects of post-stroke pain and other post-stroke complications.¹⁶

Bibliometrics is a comprehensive science mapping analysis tool for analyzing and processing massive literature information, improve the efficiency of scientific research.¹⁷ It is extensively used to visualize the citation, cooperation, co-occurrence and other relationships within the literatures, and construct various types of knowledge maps,^17–19 and explore the critical paths, research hotspots, and frontiers of the evolution of this discipline or field.²⁰ In the past 10 years, bibliometric analyses have been conducted on other stroke-related research hotspots, such as inflammasomes,²¹ traditional medicine,²² and rehabilitation treatment.²³ They used bibliometric methods to objectively present the global trend of pathogenesis, treatments of stroke and to provide important information for relevant researchers.

The pathogenesis mechanisms of PSP are not so clear, and there is currently a lack of effective medical treatments, hence it is necessary to establish a sufficient understanding of this disease.^5,24 Limited number of studies have used bibliometric methods to analyze the overall aspects pertaining to PSP currently. Therefore, this study aimed to methodically offer a comprehensive scientific analysis of published research within the past 10 years using a bibliometric analysis. The results of the present study would provide valuable reference information for researchers about identification of the current focus and challenges in the research evidence of post-stroke pain.

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Poststroke pain may be controlled by targeting neuropathic symptoms

 This is after the fact, WHOM will be doing the research that will prevent post stroke pain?

Poststroke pain may be controlled by targeting neuropathic symptoms

LAS VEGAS — Central neuropathic pain can be challenging to treat, but several pharmacologic and nonpharmacologic options are available, according to a presenter at BRAINWeek 2022.

“Central neuropathic pain is one of the most difficult pain syndromes to treat,” Michael Bottros, MD, associate professor of anesthesiology and clinical operations and medical director of pain services at Keck School of Medicine the University of Southern California, Los Angeles, said during his presentation. “There are a number of reasons for developing central neuropathic pain syndromes, and stroke is just one of them.”

Source: Adobe Stock.

Bottros explained that pain is among the most common complications of stroke, with an estimated prevalence between 39% and 55%, and tends to appear in central locations like the head, shoulders and upper extremities. Central poststroke pain (CPSP) is neuropathic in origin and affects sensory pathways, accounting for roughly 25% of poststroke pain cases, he said.

Onset of poststroke pain, Bottros stated, can develop immediately following stroke in some patients, 3 to 6 months after stroke in others and up to several years in some. However, CPSP onset within a few months is most common, with later onset a possible sign of stroke recurrence.

“Pain is the most common complication,” Bottros said. “The majority of pain described by people who have a stroke is musculoskeletal.”

To make an accurate pain assessment, clinicians should work around emotional response in their patients, he noted, and find an accurate and objective alternative to pain scales, particularly in cases of CPSP.

Bottros cited the Quantitative Sensory Testing (QST) method as the most objective, as CPSP encompasses a range of pain sensations, locations and emotions within patients that can interfere with diagnosis.

First-line treatment for CPSP is pharmacologic, Bottros said, and includes antidepressants such as amitriptyline, while anticonvulsants like gabapentin and pregabalin are good second-line choices. Lamotrigine monotherapy also is moderately effective and generally well tolerated, although this treatment comes with more serious potential side effects. And while opioids are considered generally ineffective in treating CPSP, Bottros reported that IV ketamine provided relatively rapid pain relief, which lasted 2 to 3 hours, in a double-blind, placebo-controlled study.

In the realm of nonpharmacologic treatment, various forms of neurostimulation (motor cortex, transcranial magnetic stimulation, deep brain and vestibular caloric) demonstrated beneficial pain reducing effects.

Regional blocking of nerves, Bottros added, resulted in fairly rapid pain reduction as a result of signals from the brain being cut off before reaching the locus of pain. This, he said, may be an indicator that pain may not be generated and perceived in the central nervous system.

“CPSP has variable timetable to onset following stroke,” Bottros said. “Sensory afferent input could play an important role in patients hiding the effects of poststroke pain.”