Central poststroke pain: A systematic review

Post stroke pain: Is there under-diagnosis in Black versus White patients?

Stroke incidence is higher and stroke outcomes are poorer in Black patients compared to White patients. Poststroke pain, however, is not a well understood stroke outcome. Using the National Institutes of Health All of Us Research Program database, we hypothesized that the dataset would demonstrate proportionately higher relative risk of poststroke pain in the Black poststroke patient population compared to the White poststroke patient population. However, our analysis showed that Black stroke patients were diagnosed with poststroke pain at a similar rate as White stroke patients. As our results are not consistent with other poststroke outcomes in the literature, this study identifies a potentially underdiagnosed patient population, highlighting the need for further research.

Comparative effectiveness of pain control between opioids and gabapentinoids in older patients with chronic pain

ABSTRACT

Gabapentinoid (GABA) prescribing has substantially increased while opioid prescribing has decreased since the 2016 Centers for Disease Control and Prevention Guidelines restricted opioid prescribing for chronic pain. The shift to GABA assumes equal analgesic effectiveness to opioids, but no comparative analgesic effectiveness data exist to support this assumption. We compared GABA to opioids by assessing changes in pain interfering with activities (activity-limiting pain) over time in patients with chronic pain. We used 2017 to 2019 data from a 20% national sample of Medicare beneficiaries diagnosed with chronic pain who initiated a GABA or opioid prescription for ≥30 continuous days and received home health care in the study year. The main outcome was the difference in reduction in pain score from pre- to post-prescription assessments between the 2 groups. Within a 60-day window before-and-after drug initiation, our sample comprised 3208 GABA users and 2846 opioid users. Reduction in post-prescription scores of pain-related interference with activities to less-than-daily pain was 48.1% in the GABA group and 41.7% in the opioid group; this remained significant (odds ratio = 1.29, 95% confidence interval: 1.17-1.43, P < 0.0001) after adjustment for patient demographics and comorbidities. The adjusted difference in reduced pain-related interference score between the 2 groups was -0.10 points on a 0 to 4 scale ( P = 0.01). Gabapentinoid use had greater odds of less-than-daily pain post-prescription, in a dose-dependent manner. Thus, GABA use was associated with a larger reduction in chronic pain than opioids, with a larger effect at higher GABA dosage. Future research is needed on functional outcomes in patients with chronic pain prescribed GABA or opioids.

"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.

Comparative efficacy and safety of acupuncture and Western medicine for poststroke thalamic pain

Poststroke thalamic pain (PSTP) is one of the most common sequelae following stroke. Analgesics, antidepressants, anticonvulsants, and surgical treatment are conventional treatment methods of PSTP, but these methods have limited efficacy, cost more, and cause a likelihood of adverse reactions. Clinical studies have shown that acupuncture has a significant analgesic effect on PSTP without obvious side effects. But, there is a lack of high-quality evidence concerning its effectiveness and safety to support its use. Therefore, this study aimed to evaluate the clinical efficacy and safety of acupuncture versus Western medicine for the treatment of PSTP to provide evidence to support clinical PSTP treatment. Searches were conducted to identify randomized controlled trials investigating the use of acupuncture for PSTP across six databases, including PubMed, the Cochrane Library, EMBASE, the China National Knowledge Infrastructure, Wan Fang Database, and the Chinese Scientific Journal Database VIP. RevMan 5.3 software was used for the meta-analysis. The results showed that compared with Western medicine, acupuncture had a higher total effective rate for the treatment of PSTP, reduced visual analog scale scores, increased beta-endorphin content, and decreased incidence of adverse reactions. However, the sample sizes of the included studies were insufficient, and the quality of the articles was relatively poor. In future studies, the clinical study design should be standardized and the sample size should be expanded to validate these results.

Oral health decline in patients after stroke: a qualitative study

Introduction To develop and implement effective oral care interventions for patients after stroke, there is a need to understand the causes behind the decline in their oral health. This qualitative study was, therefore, undertaken to explore experiences and views of health service providers about the causes of oral health decline in this group of patients.Methods A purposively selected sample of healthcare service providers who work in two NHS Trusts in the North of England were interviewed utilising a semi-structured interview technique. Interviews were conducted with the assistance of a topic guide and continued until data saturation (n = 30) was reached. The constant comparative approach was used to analyse the data.Results Two major factors, perceived by the participants, were thought to cause oral health decline in patients after stroke. Post-stroke neurological deficits resulting in oral-related functional disturbances was the first. The second was the barriers leading to difficulties in performing or receiving daily oral care. These barriers were related to the patients, their service providers, or the environment in which care is being delivered.Conclusions This study described the major factors affecting the oral health of patients after stroke, which can offer a starting point for developing effective oral care interventions for them.

Relief of Central Poststroke Pain Affecting Both the Arm and Leg on One Side by Double-independent Dual-lead Spinal Cord Stimulation Using Fast-acting Subperception Therapy Stimulation: A Case Report

Central poststroke pain is a chronic, intractable, central neuropathic pain. Spinal cord stimulation is a neuromodulation therapy for chronic neuropathic pain. The conventional stimulation method induces a sense of paresthesia. Fast-acting subperception therapy is one of the latest new stimulation methods without paresthesia. A case of achieving pain relief of central poststroke pain affecting both the arm and leg on one side by double-independent dual-lead spinal cord stimulation using fast-acting subperception therapy stimulation is presented. A 67-year-old woman had central poststroke pain due to a right thalamic hemorrhage. The numerical rating scale scores of the left arm and leg were 6 and 7, respectively. Using dual-lead stimulation at the Th 9-11 levels, a spinal cord stimulation trial was performed. Fast-acting subperception therapy stimulation achieved pain reduction in the left leg from 7 to 3. Therefore, a pulse generator was implanted, and the pain relief continued for 6 months. Then, two additional leads were implanted at the C 3-5 levels, and pain in the arm decreased from 6 to 4. Independent setting and adjustments of the dual-lead stimulation were required because the thresholds of paresthesia perception were significantly different. To achieve pain relief in both the arm and leg, double-independent dual-lead stimulation placed at cervical and thoracic levels is an effective treatment. Fast-acting subperception therapy stimulation may be effective for central poststroke pain, especially in cases where the paresthesia is perceived as uncomfortable or the conventional stimulation itself is ineffective.

Modulation of melatonin to the thalamic lesion-induced pain and comorbid sleep disturbance in the animal model of the central post-stroke hemorrhage

The devastating chronic central post stroke pain is associated with variety of comorbidities. Disrupted sleep is a severe comorbidity, causing an increase in the suicide rate, due to CPSP’s pain symptom. Melatonin is a well-known jet-lag compound, which helps in entrainment of sleep cycle. Accordingly, whether melatonin as a therapeutic measurement for the regulation of sleep disturbance related to central post stroke pain remains unclear. Exogenous melatonin administration entrained the disrupted 24 h circadian cycle, more effectively after 2 and 3 week of administration. The effect of melatonin was persisted on 4th week too, when melatonin administration was discontinued. Also, melatonin ameliorated the pain due to distorted sleep-activity behavior after melatonin administration for 3 weeks. The low levels of melatonin in blood plasma due to CPSP were restored after 3 weeks of melatonin administration. After 30 mg/kg melatonin administrations for 3 weeks, all the disrupted resting and activity behaviors were reduced during light and dark periods. The results suggested that melatonin significantly ameliorated CPSP’s pain symptoms and comorbid sleep disturbance showing in activity behavior.

Dissecting neuropathic from poststroke pain: the white matter within

ABSTRACT

Poststroke pain (PSP) is a heterogeneous term encompassing both central neuropathic (ie, central poststroke pain [CPSP]) and nonneuropathic poststroke pain (CNNP) syndromes. Central poststroke pain is classically related to damage in the lateral brainstem, posterior thalamus, and parietoinsular areas, whereas the role of white matter connecting these structures is frequently ignored. In addition, the relationship between stroke topography and CNNP is not completely understood. In this study, we address these issues comparing stroke location in a CPSP group of 35 patients with 2 control groups: 27 patients with CNNP and 27 patients with stroke without pain. Brain MRI images were analyzed by 2 complementary approaches: an exploratory analysis using voxel-wise lesion symptom mapping, to detect significant voxels damaged in CPSP across the whole brain, and a hypothesis-driven, region of interest-based analysis, to replicate previously reported sites involved in CPSP. Odds ratio maps were also calculated to demonstrate the risk for CPSP in each damaged voxel. Our exploratory analysis showed that, besides known thalamic and parietoinsular areas, significant voxels carrying a high risk for CPSP were located in the white matter encompassing thalamoinsular connections (one-tailed threshold Z > 3.96, corrected P value <0.05, odds ratio = 39.7). These results show that the interruption of thalamocortical white matter connections is an important component of CPSP, which is in contrast with findings from nonneuropathic PSP and from strokes without pain. These data can aid in the selection of patients at risk to develop CPSP who could be candidates to pre-emptive or therapeutic interventions.

Contralateral C7 nerve transfer in the treatment of upper-extremity paralysis: a review of anatomical basis, surgical approaches, and neurobiological mechanisms

The previous three decades have witnessed a prosperity of contralateral C7 nerve (CC7) transfer in the treatment of upper-extremity paralysis induced by both brachial plexus avulsion injury and central hemiplegia. From the initial subcutaneous route to the pre-spinal route and the newly-established post-spinal route, this surgical operation underwent a series of innovations and refinements, with the aim of shortening the regeneration distance and even achieving direct neurorrhaphy. Apart from surgical efforts for better peripheral nerve regeneration, brain involvement in functional improvements after CC7 transfer also stimulated scientific interest. This review summarizes recent advances of CC7 transfer in the treatment of upper-extremity paralysis of both peripheral and central causes, which covers the neuroanatomical basis, the evolution of surgical approach, and central mechanisms. In addition, motor cortex stimulation is discussed as a viable rehabilitation treatment in boosting functional recovery after CC7 transfer. This knowledge will be beneficial towards improving clinical effects of CC7 transfer.

Difference in Analgesic Effects of Repetitive Transcranial Magnetic Stimulation According to the Site of Pain

High-frequency repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex for neuropathic pain has been shown to be effective, according to systematic reviews and therapeutic guidelines. However, our large, rigorous, investigator-initiated, registration-directed clinical trial failed to show a positive primary outcome, and its subgroup analysis suggested that the analgesic effect varied according to the site of pain. The aim of this study was to investigate the differences in analgesic effects of rTMS for neuropathic pain between different pain sites by reviewing our previous clinical trials. We included three clinical trials in this mini meta-analysis: a multicenter randomized controlled trial at seven hospitals (N = 64), an investigator-initiated registration-directed clinical trial at three hospitals (N = 142), and an exploratory clinical trial examining different stimulation parameters (N = 22). The primary efficacy endpoint (change in pain scale) was extracted for each patient group with pain in the face, upper limb, or lower limb, and a meta-analysis of the efficacy of active rTMS against sham stimulation was performed. Standardized mean difference (SMD) with 95% confidence interval (CI) was calculated for pain change using a random-effects model. The analgesic effect of rTMS for upper limb pain was favorable (SMD = -0.45, 95% CI: -0.77 to -0.13). In contrast, rTMS did not produce significant pain relief on lower limb pain (SMD = 0.04, 95% CI: -0.33 to 0.41) or face (SMD = -0.24, 95% CI: -1.59 to 1.12). In conclusion, these findings suggest that rTMS provides analgesic effects in patients with neuropathic pain in the upper limb, but not in the lower limb or face, under the conditions of previous clinical trials. Owing to the main limitation of small number of studies included, many aspects should be clarified by further research and high-quality studies in these patients.

The occurrence of neuropathic pain following surgery of brainstem cavernous malformations

BACKGROUND AND PURPOSE

This study aimed to assess the occurrence and significance of postoperative neuropathic pain (NP) in patients with surgically treated brainstem cavernous malformations (BSCMs).

METHODS

Seventy-four BSCM patients surgically treated between 2003 and 2019 were reviewed for the occurrence of postoperative NP and related treatment. The relevance of BSCM location, preoperative characteristics, influence on functional outcome, postoperative health-related quality of life (HRQOL) and life satisfaction was evaluated.

RESULTS

Six out of 74 patients (8%) suffered from NP. The Leeds Assessment of Neuropathic Symptoms and Signs scores ranged from 12 to 16 (mean 14.28 ± 1.6). Visual analog scale pain was 5.2 ± 2.0. NP had no effect on preoperative characteristics or functional outcome. Bodily pain (HRQOL) and vocational time (life satisfaction) were significantly decreased in NP compared to non-NP patients. Specific BSCM location (regarding brainstem nuclei involved in pain processing) and other preoperative patient- and BSCM-related parameters were not associated with the occurrence of postoperative NP. Three out of six patients were currently under NP-specific treatment. The proportion of patients suffering from postoperative NP (8%) was substantially higher compared to previously published studies. The pain affected the HRQOL of patients, most of whom were insufficiently treated and not satisfied with treatment results.

CONCLUSION

Our findings may help to raise awareness for postoperative NP in BSCM, which is essential to improve diagnosis and initiation of proper treatment, as well as preoperative informed consent of patients.

MicroRNA-133b-3p targets purinergic P2X4 receptor to regulate central poststroke pain in rats

Central poststroke pain (CPSP) is a neuropathic pain syndrome that usually occurs after cerebrovascular accidents. Currently, the pathogenesis of CPSP is not fully understood. Purinergic P2X4 receptor (P2X4R) is implicated in neuropathic pain including CPSP. Herein, we demonstrated that the levels of microRNA-133b-3p (miR-133b-3p), which targets P2X4R transcripts, were significantly downregulated in the ventral posterolateral nucleus of the thalamus (VPL), cerebrospinal fluid (CSF), and plasma of CPSP rats. The expression levels of miR-133b-3p negatively correlated with the severity of allodynia. Genetic knockdown of P2X4R in the VPL protected CPSP rats against allodynia. Similarly, genetic overexpression of miR-133b-3p in the VPL reversed the allodynia established in CPSP rats via downregulation of P2X4R expression. Treatment using gabapentin in CPSP rats significantly restored the decreased miR-133b-3p expression in the VPL, CSF, and plasma and blocked allodynia in CPSP rats. The administration of an miR-133b-3p inhibitor into the VPL abolished the antiallodynic activity of gabapentin. This mechanism was associated with P2X4R expression and involved the endogenous opioid system. Human patients with CPSP showed decreased plasma levels of miR-133b-3p compared with those of control participants. Logistic regression analysis of our patient cohort showed that determining plasma levels of miR-133b-3p may be useful for CPSP diagnosis and treatment.

Defining and Managing Pain in Stroke and Traumatic Brain Injury Research

Neurologic conditions such as stroke and traumatic brain injury are challenging conditions to study in humans. Animal models are necessary to uncover disease processes and develop novel therapies. When attempting to model these or other neurologic diseases, the accompanying anesthesia and analgesia create variables that are not part of the onset of the clinical disease in the human population but are critical components of the postinjury care both in humans and animals. To maximize model validity, researchers must consider whether the disease process or a novel therapy is being studied. Damage to the neurons of the brain or the spinal cord is not painful at the neural tissue itself, but alterations to nociceptive signaling along the pain pathway can induce chronic pain. In addition, trauma or surgery leading to the event is associated with damage to peripheral tissue. Inflammation is inextricably associated with tissue injury. Inflammation is known to evoke nociception in the periphery and drive long-term changes to neurons in the CNS. Analgesics and anesthetics alter these responses yet are required as part of humane animal care. Careful planning for effective drug administration consistent with the standard of care for humans and equivalent animal care is required.

Chronic Central Pain Among Community-Dwelling Survivors of Moderate-to-Severe Traumatic Brain Injury: A Quantitative Sensory Testing Study

Background:

Central pain associated with changes in sensory thresholds is one of the most enduring consequences of major trauma. Yet it remains sparsely studied among community-dwelling survivors of moderate-to-severe traumatic brain injury (TBI).

Purpose:

To describe and compare thermal and mechanical sensory thresholds in home-based patients with and without central pain after moderate-to-severe TBI with a cohort of healthy controls.

Design:

Cross-sectional.

Method:

Thresholds for cold/heat detection, thermal pain, touch, and distorted sensation were gathered using quantitative sensory testing (QST). QST was performed on the painful and contralateral pain-free body regions in TBI participants with pain (TBI-P) and on both forearms in TBI participants without pain (TBI-NP) and healthy controls (HC). Central pain was characterized using the Brief Pain Inventory–Short Form.

Results:

We tested 16 TBI-P patients, 17 TBI-NP patients, and 16 HC. Mean time since injury for TBI patients was 24 ± 15 months. TBI-P and TBI-NP patients showed significant loss in innocuous mechanical sensitivity compared to HC ( F = 18.929; Bonferroni-adjusted p ≤ .001). Right–left differences in cold pain sensations were significantly larger in TBI-P than in TBI-NP and HC participants ( F = 14.352; Bonferroni-adjusted p ≤ .001). Elevated heat sensitivity thresholds were also observed in TBI-P participants but remained within normal range.

Conclusion:

Damage to cutaneous mechanoreceptors is a necessary, but not sufficient, condition for the development of chronic central pain following TBI. Damage or incomplete recovery of cutaneous thermoreceptors may be a contributing factor to chronic pain after TBI.

Predictive Factors Associated with Pain Relief of Spinal Cord Stimulation for Central Post-stroke Pain

The efficacy and predictive factors associated with successful spinal cord stimulation (SCS) for central post-stroke pain (CPSP) have yet to be definitively established. Thus, this study evaluated the rates of pain relief found after more than 12 months and the predictive factors associated with the success of SCS for CPSP. The degree of pain after SCS in 18 patients with CPSP was assessed using the Visual Analog Scale preoperatively, at 1, 6 and 12 months after surgery, and at the time of the last follow-up. After calculating the percentage of pain relief (PPR), patients were separated into two groups. The first group exhibited continuing PPR ≥30% at more than 12 months (effect group) while the second group exhibited successful/unsuccessful trials followed by decreasing PPR <30% within 12 months (no effect group). Pain relief for more than 12 months was achieved in eight out of 18 (44.4%) patients during the 67.3 ± 35.5 month follow-up period. Statistically significant differences were found for both the age and stroke location during comparisons of the preoperative characteristics between the two groups. There was a significantly younger mean age for the effect versus the no effect group. Patients with stoke in non-thalamus were significantly enriched in effect group compared with those with stoke in thalamus. Multivariable analysis using these two factors found no statistical differences, suggesting that these two factors might possibly exhibit the same behaviors for the SCS effect. These results suggest that SCS may be able to provide pain relief in young, non-thalamus stroke patients with CPSP.