Short-term cervical spinal cord stimulation for central post-stroke pain: a case report and literature review

Introduction

Post-stroke central pain is disabling yet ineffectively treated with routine medical intervention. In this study, the authors presented an alternative neuromodulation therapy and conducted a brief narrative literature review to examine current evidence of spinal cord stimulation treatment for central post-stroke pain.

Case presentation

Here, the authors reported a case of severe post-stroke syndrome, who achieved satisfactory improvement of pain symptom, as well as muscle rigidity with a novel neuromodulation therapy of short-term implantation of cervical spinal cord stimulation.

Clinical discussion

It remains a great challenge in the management of post-stroke pain, which in turn significantly reduces the quality of life and worsens the burden on the public health system. Spinal cord stimulation therapy is an emerging neuromodulation approach to restore pathological pain status and functional impairment to provide a prospective insight into neuromodulation and rehabilitation options in the management of post-stroke syndrome.

Conclusion

A potential role of spinal cord stimulation in the treatment of post-stroke pain is proposed in combined with traditional medication or other neuromodulation strategies, to achieve better control of pain in the future.

"I will try anything" the experience of working age stroke survivors living with chronic post-stroke pain: an interpretative phenomenological analysis

PURPOSE

To investigate the experience of working age adults living with chronic post-stroke pain in the United Kingdom (UK).

METHODS

Semi-structured interviews were conducted with eight working age (46-64 years) UK-based stroke survivors who experience chronic post-stroke pain (≥3 months). The interviews were analysed using interpretative phenomenological analysis.

RESULTS

The analysis led to three Group Experiential Themes: "The Solitude of the Pain Experience," "Unsatisfactory Healthcare and the Need for Self-Care" and "The Development of Pain Acceptance." Findings suggest that individuals see their post-stroke pain as an invisible disability, which is overlooked and misunderstood by others. Furthermore, in the absence of a differential post-stroke pain diagnosis, clear, accurate information and alternatives to pharmacological treatments, individuals with post-stroke pain invest their own resources in finding answers and a way to live with the pain.

CONCLUSIONS

The findings suggest the need for further education on post-stroke pain for healthcare professionals, the consideration of pain in post-stroke assessments, the need for clear differential pain diagnoses and the provision of accurate information to patients. Research is needed to establish non-pharmacological evidence-based treatment approaches, such as pain management programmes, peer support and psychological interventions.

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

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.

The effect and mechanism of exercise for post-stroke pain

One of the common negative effects of a stroke that seriously lowers patients' quality of life is post-stroke pain (PSP). Thus, exercise in PSP management has become a hot research topic. The main advantages of exercise therapy are affordability and ease of acceptance by patients compared to other treatment methods. Therefore, this article reviews the effectiveness and possible mechanisms of exercise interventions for PSP. Exercise training for patients with PSP not only improves physical function but also effectively reduces pain intensity and attenuates the behavioral response to pain. In addition, exercise therapy can improve brain function and modulate levels of pro-inflammatory and neurotrophic factors to exert specific analgesic effects. Potential mechanisms for exercise intervention include modulation of synaptic plasticity in the anterior cingulate gyrus, modulation of endogenous opioids in vivo, reversal of brain-derived neurotrophic factor overexpression, inhibition of purinergic receptor (P2X4R, P2X7R) expression, and inhibition of microglia activation. However, current research on exercise for PSP remains limited, and the sustainable benefits of exercise interventions for PSP need to be further investigated.

Psychological interventions for post stroke pain: A systematic review

Chronic pain is prevalent after stroke and has a significant impact on quality of life. Research demonstrates the efficacy of psychological interventions for mixed chronic pain conditions. This review aimed to assess evidence on the effectiveness of psychological interventions for chronic pain in people with stroke. PubMed, PsychINFO, Embase, and CINAHL were searched from inception to 31 January 2021 at all levels of evidence. Psychological interventions assessing chronic pain in adults following stroke as a primary outcome were included. All outcomes related to pain quality were included (e.g., intensity, frequency, duration). Study quality was assessed using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Case Reports and Risk of Bias in N-of-1 Trials (RoBiNT) Scale. Three single n case reports were included. A narrative synthesis was performed, indicating that psychological interventions may reduce chronic post-stroke pain; however, overall quality appraisal of the included studies was poor, owing to the low internal validity found in the single-n case report designs. The limited evidence suggests that psychological interventions may have clinical utility in reducing chronic post-stroke pain. However, owing to the paucity and quality of studies found, the results must be treated with caution. More rigorous research is needed.

Bilateral Motor Cortex tDCS Effects on Post-Stroke Pain and Spasticity: A Three Cases Study

Stroke patients frequently suffer from chronic limb pain, but well-suited treatment approaches have been not established so far. Transcranial direct current stimulation (tDCS) is a safe and non-invasive brain stimulation technique that alters cortical excitability, and it has been shown that motor cortex tDCS can reduce pain. Some data also suggest that spasticity may be improved by tDCS in post-stroke patients. Moreover, multiple sessions of tDCS have shown to induce neuroplastic changes with lasting beneficial effects in different neurological conditions. The aim of this pilot study was to explore the effect of multiple anodal tDCS (atDCS) sessions on upper limb pain and spasticity of stroke patients, using a within-subject, crossover, sham-controlled design. Brain damage was of similar extent in the three patients evaluated, although located in different hemispheres. The results showed a significant effect of 5 consecutive sessions of atDCS, compared to sham stimulation, on pain evaluated by the Adaptive Visual Analog Scales -AVAS-, and spasticity evaluated by the Fugl-Meyer scale. In two of the patients, pain was completely relieved and markedly reduced, respectively, only after verum tDCS. The pain improvement effect of atDCS in the third patient was considerably lower compared to the other two patients. Spasticity was significantly improved in one of the patients. The treatment was well-tolerated, and no serious adverse effects were reported. These findings suggest that multiple sessions of atDCS are a safe intervention for improving upper limb pain and spasticity in stroke patients, although the inter-individual variability is a limitation of the results. Further studies including longer follow-up periods, more representative patient samples and individualized stimulation protocols are required to demonstrate the efficacy and safety of tDCS for improving limb symptoms in these patients.

Opioids in Post-stroke Pain: A Systematic Review and Meta-Analysis

Background: Post-stroke pain is one of the most common sequelae of stroke, which stands among the leading causes of death and adult-acquired disability worldwide. The role and clinical efficacy of opioids in post-stroke pain syndromes is still debated.

Objectives: Due to the important gap in knowledge on the management of post-stroke pain, this systematic review aimed at assessing the efficacy of opioids in post-stroke pain syndromes.

Methods: A literature search was conducted on databases relevant for medical scientific literature, i.e. PubMed/MEDLINE, Scopus, Web of Science and Cochrane Library databases from databases inception until August 31^st, 2020 for clinical trials assessing the effects of opioids and opioid antagonists on pain reduction and pain related symptoms in patients with post-stroke pain syndromes. Studies assessing the effects of other medications (e.g., tricyclic antidepressant, pregabalin) or non - pharmacological management strategies (e.g., neurostimulation techniques) were excluded. The selected studies have been subjected to examination of the risk of bias.

Results: The literature search retrieved 83,435 results. After duplicates removal, 34,285 articles were title and abstract screened. 25 full texts were assessed and 8 articles were identified to be eligible for inclusion in the qualitative summary and narrative analysis, of which three were placebo-controlled and two were dose-response. Among placebo-controlled studies, two evaluated the analgesic effect of morphine and one assessed the effects of the opioid antagonist naloxone on patients with central post-stroke pain. With regard to dose-response studies, both were on patients with central post-stroke pain, one assessing the efficacy of levorphanol, and the other on naloxone. Seven out of eight included studies showed an overall slight analgesic effect of opioids, with less consistent effects on other pain-related symptoms (e.g., mood, quality of life). The randomized controlled trials were subjected to meta-analysis and rating of the quality of evidence for the two outcomes considered according to GRADE (Grading of Recommendations, Assessment, Development and Evaluations) system. The overall results are inconclusive because of the small number of studies and of patients.

Conclusions: The limited number of the included studies and their heterogeneity in terms of study design do not support the efficacy of opioids in post-stroke pain and in pain-related outcomes. Large double-blind randomized clinical trials with objective assessment of pain and related symptoms are needed to further investigate this topic.

A Narrative Review of Persistent Post-Stroke Headache - A New Entry in the International Classification of Headache Disorders, 3rd Edition

BACKGROUND

Persistent post-stroke headache is a clinical entity that has recently entered the International Classification of Headache Disorders, 3rd edition. In contrast to acute headache attributed to stroke, the epidemiology, clinical features, potential pathophysiology, and management of persistent post-stroke headache have not been reviewed.

METHODS

We summarize the literature describing persistent headache attributed to stroke.

RESULTS

Persistent headache after ischemic or hemorrhagic stroke affects up to 23% of patients. These persistent headaches tend to have tension-type features and are more frequent and severe than acute stroke-related headaches. Risk factors include younger age, female sex, pre-existing headache disorder, and comorbid post-stroke fatigue or depression. Other factors including obstructive sleep apnea or musculoskeletal imbalances may contribute to headache persistence. Although more evidence is needed, it may be reasonable to treat persistent post-stroke headache according to headache semiology.

CONCLUSION

Recognition of persistent post-stroke headache as a separate clinical entity from acute stroke-attributed headache is the first step toward better defining its natural history and most effective treatment strategies.

A case report of a thalamic stroke associated with sudden disappearance of severe chronic low back pain

BACKGROUND

Chronic pain conditions are associated with neuroplasticity within the central nervous system. In most patients the maladaptive consequence of neuroplasticity supports prolonged course of chronic pain, despite the absence of a commensurate etiology. From a pain neuromatrix perspective it can involve three different circuits within the central nervous system; the classical sensory pathway, the limbic system pathway, and the associative pathways involving the parietal cortical connections. Although this can be conceptualized as a fluid system composed of several interacting networks, it can be broadly separated into a nociceptive specific network of spino-thalamic neurons and second order neurons beyond thalamus that are not nociceptor specific. Thalamus acts as an important relay station that conveys nociceptive signaling to higher centres. Neuroplastic changes can potentially involve any parts within this neuromatrix. It is very uncommon to observe the sudden disappearance of such a chronic pain condition.

METHODS AND RESULTS

In this case report, the author describes the clinical course of a patient with severe chronic low back pain (CLBP), whose pain suddenly disappeared after a stroke involving his left thalamus. Although extremely rare, existing case reports of such disappearance of pain with a secondary stroke in patients suffering from central post stroke pain (CPSP) are reviewed. The author further postulates hypotheses that could potentially explain this phenomenon based on the existing knowledge.

CONCLUSIONS AND IMPLICATIONS

Although extremely rare and unpredictable, a thalamic stroke involving areas that are involved in chronic pain signaling can potentially lead to disappearence of an existing chronic pain condition. This is the first case report of such sudden disappearence of CLBP with well established nociceptive pathology supported by clinical and imaging findings. This unique case report could potentially generate ideas for future research and clinical treatment in the field of neuromodulation and brain stimulation.

Deep brain stimulation of the ventral striatum/anterior limb of the internal capsule in thalamic pain syndrome: study protocol for a pilot randomized controlled trial

BACKGROUND

Chronic neuropathic pain in thalamic pain syndrome remains intractable. Its poor response is ascribed to destruction of the integrated neuromatrix in experience of pain. Deep brain stimulation is a promising technique to modulate activity of implicated structures. However, traditional approaches targeting sensori-motor substrates have failed to affect disability. The offending lesion in thalamic pain syndrome that almost invariably destroys sensory pain pathways may render these classical approaches ineffective. Instead, we hypothesize that targeting structures representing emotion and affective behavior-ventral striatum/anterior limb of the internal capsule, may alleviate disability.

METHODS/DESIGN

We present the design of our phase I randomized, double-blinded, sham-controlled, crossover trial that examines safety, feasibility and efficacy of our proposed approach. In our ongoing trial, we intend to enroll ten patients with thalamic pain syndrome. Following implantation, patients are randomized to receive active deep brain stimulation to the ventral striatum/anterior limb of the internal capsule or sham for 3 months, after which they are crossed over. The primary endpoint is Pain Disability Index. Other outcomes include visual analog scale, depression and anxiety inventories, quality of life, and functional neuroimaging.

DISCUSSION

Designing trials of deep brain stimulation for pain is challenging owing to the ethical-scientific dilemma of introducing a control arm, complicated blinding, heterogeneous etiologies, patient expectations, and inadequate assessment of disability. The quality of evidence in the field is classified as level III (poor) because it mainly includes a multitude of uncontrolled case series reporting variable outcomes, with little regard for the placebo effect related to implantation. Without valid data on efficacy, use of deep brain stimulation for pain remains "off label". We present our trial design to discuss feasibility of conducting sham-controlled phase I studies that may represent significant refinement for the field. Double-blinding would reduce influence of patient expectations and therapeutic confusion amongst investigators. With a cross-over approach, the dilemma regarding including a control group can be mitigated. Use of homogeneous etiology, measurement of disability, depression and quality of life, besides pain perception, all represent strategies to evaluate efficacy rigorously. Functional imaging would serve to define mechanisms underlying observed effects and may help optimize future targeting.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01072656.

The biochemical origin of pain--proposing a new law of pain: the origin of all pain is inflammation and the inflammatory response. Part 1 of 3--a unifying law of pain

We are proposing a unifying theory or law of pain, which states: the origin of all pain is inflammation and the inflammatory response. The biochemical mediators of inflammation include cytokines, neuropeptides, growth factors and neurotransmitters. Irrespective of the type of pain whether it is acute or chronic pain, peripheral or central pain, nociceptive or neuropathic pain, the underlying origin is inflammation and the inflammatory response. Activation of pain receptors, transmission and modulation of pain signals, neuro plasticity and central sensitization are all one continuum of inflammation and the inflammatory response. Irrespective of the characteristic of the pain, whether it is sharp, dull, aching, burning, stabbing, numbing or tingling, all pain arise from inflammation and the inflammatory response. We are proposing a re-classification and treatment of pain syndromes based upon their inflammatory profile. Treatment of pain syndromes should be based on these principles: 1. Determination of the inflammatory profile of the pain syndrome; 2. Inhibition or suppression of production of the appropriate inflammatory mediators, e.g. with inflammatory mediator blockers or surgical intervention where appropriate; 3. Inhibition or suppression of neuronal afferent and efferent (motor) transmission, e.g. with anti-seizure drugs or local anesthetic blocks; 4. Modulation of neuronal transmission, e.g. with opioid medication. At the L.A. Pain Clinic, we have successfully treated a variety of pain syndromes by utilizing these principles. This theory of the biochemical origin of pain is compatible with, inclusive of, and unifies existing theories and knowledge of the mechanism of pain including the gate control theory, and theories of pre-emptive analgesia, windup and central sensitization.