Somatosensory symptoms and signs and conditioned pain modulation in chronic post-stroke shoulder pain

Assessment approaches for hemiplegic shoulder pain in people living with stroke - A scoping review

PURPOSE

Hemiplegic shoulder pain (HSP) is reported in up to 40% of people with stroke. Causes of HSP are often multifactorial. To inform appropriate treatment, reliable/valid assessments are critical. The aim of this scoping review was to collate assessment approaches used in studies where the primary outcome was HSP, and to identify how frequently each assessment approach was used.

METHODS

A systematic search, including studies from 2000-2023 was conducted of the MEDLINE, EMBASE, CINAHL, AMED, Biomed Central, and Cochrane Library databases, with four key terms used: "assess", "stroke", "pain" and "shoulder". All primary studies published in English language fulfilling the reviews inclusion criteria were included. Six reviewers extracted the data.

RESULTS

A total of 29 assessment methods for HSP were identified from 124 studies. The common assessments were: Visual Analogue Scale (n = 75, 60%), Passive Range of Movement (n = 65, 52%), Fugl-Meyer Assessment (n = 32, 26%), glenohumeral subluxation (n = 30, 24%) and Numerical Rating Scale (n = 27, 22%).

CONCLUSION

A wide range of assessment approaches was identified for HSP, and some are used more than others. A fully comprehensive assessment that considers different aspects of pain including severity and timing, functioning, and the psychological burden, is needed in this area of practice to be able to guide appropriate treatment.

Is there a relationship between somatosensory impairment and the perception of pain in stroke survivors? An exploratory study

Pain and somatosensory impairments are commonly reported following stroke. This study investigated the relationship between somatosensory impairments (touch detection, touch discrimination and proprioceptive discrimination) and the reported presence and perception of any bodily pain in stroke survivors. Stroke survivors with somatosensory impairment ( N  = 45) completed the Weinstein Enhanced Sensory Test (WEST), Tactile Discrimination Test, and Wrist Position Sense Test for quantification of somatosensation in both hands and the McGill Pain Questionnaire, visual analog scale and the Neuropathic Pain Symptom Inventory (NPSI) for reporting presence and perception of pain. No relationship was observed between somatosensory impairment (affected contralesional hand) of touch detection, discriminative touch or proprioceptive discrimination with the presence or perception of pain. However, a weak to moderate negative relationship between touch detection in the affected hand (WEST) and perception of pain intensity (NPSI) was found, suggesting that stroke survivors with milder somatosensory impairment of touch detection, rather than severe loss, are likely to experience higher pain intensity [rho = -0.35; 95% confidence interval (CI), -0.60 to -0.03; P  = 0.03]. Further, a moderate, negative relationship was found specifically with evoked pain (NPSI) and touch detection in the affected hand (rho = -0.43; 95% CI, -0.72 to -0.02; P  = 0.03). In summary, our findings indicate a weak to moderate, albeit still uncertain, association, which prevents making a definitive conclusion. Nevertheless, our findings contribute to our understanding of the complexities surrounding the experience of pain in survivors of stroke and provide direction for future studies.

Effects of photobiomodulation on pain, lactate and muscle performance (ROM, torque, and EMG parameters) of paretic upper limb in patients with post-stroke spastic hemiparesis-a randomized controlled clinical trial

The objective of the study was to investigate the impact of photobiomodulation (PBM) on the paretic upper limb in post-stroke patients with spastic hemiparesis and to understand the potential of PBM as a long-term non-invasive therapy for reducing the side effects caused by spasticity in the hemiparetic upper limb after a stroke. This is a double-blind randomized clinical trial constituted of 27 participants, being Control group (CG = 12 healthy individuals) and PBM group (PBMG = 15 post-stroke individuals). In the CG, the baseline blood lactate (BL) was evaluated, followed by the evaluation of the IC torque of the biceps and triceps muscles, with the isokinetic dynamometer associated with surface electromyography (EMG) and, subsequently, a new measurement of BL. The PBMG received 10 sessions of treatment with PBM (780 nm, Power: 100 mV, Power Density: 3.18 W/cm2, Energy: 4 J, Fluency: 127.4 J/cm2, Time: 40 s per point and 1.280 s total, Spot: 0.0314 cm2, 32 Points: 16 points (brachial biceps) and 16 points (brachial triceps) applied with contact at 90°, Total Energy: 64 J), which in the pre-treatment evaluation measured BL, the visual analogue scale (VAS) of pain; torque and EMG of the same muscles in the IC, subsequently, a new measurement of VAS and BL, and measurement of range of motion (ROM) during the reaching movement. At the conclusion of the ten sessions, all participants underwent a reassessment, wherein all tests originally administered during the initial evaluation were repeated. Subsequently, the data were analyzed using the Shapiro-Wilk normality test. For related data, the paired t-test was used for normal distributions and the Wilcoxon test for non-normal data. For unrelated data, the t test was used for normal distributions and the Mann-Whitney test for non-normal data. Muscle torque was higher for the CG, with a significant difference (CGxPBMG = p < 0.0001). There was no significant difference between the EMG values of the CG in relation to the Pre-PBM phase and with the Post-PBM phase of the PBMG (p > 0.05). On the other hand, there was a 38% reduction in pain reported by hemiparetic patients (p = 0.0127) and a decrease in BL in the PBMG. Post-PBM ROM increased by 46.1% in the elbow extension of the paretic limb. In conclusion, Photobiomodulation (PBM) demonstrated significant improvements in muscle performance, reducing fatigue and pain levels, and enhancing range of motion in post-stroke patients with spastic hemiparesis. These findings support the potential integration of PBM into rehabilitation protocols, but further research and clinical trials are needed to validate and expand upon these promising outcomes.

Hemiplegic shoulder pain affects ipsilesional aiming movements after stroke: a cross-sectional study

BACKGROUND

Hemiplegic shoulder pain (HSP) is common after stroke. The pain perception may exacerbate changes in the motor behavior of the ipsi-lesional upper limb, contributing to the functional decline of an individual's motor performance.

OBJECTIVE

This study evaluates the influence of pain perception on the aiming movements performed with the ipsilesional upper limb in individuals with unilateral chronic stroke.

METHODS

A cross-sectional study was conducted with 41 participants divided into three groups: 1) stroke with contralesional shoulder pain ≥ 3 by the Visual Numerical Pain Scale (SPSG; n = 13); 2) stroke no shoulder pain (nSPSG; n = 14); and 3) healthy control (CTG; n = 14) matched by sex and age. Individuals with stroke were matched for the severity of sensorimotor impairment by the Fugl-Meyer upper limb subscale and the injured hemisphere side. Stroke groups performed aiming movements with the ipsilesional upper limb and the CTG with the corresponding limb using a pen tip on the sensitive surface of a digitizing tablet. Performance across groups was compared by one-way analysis of variance, considering the time since injury as a covariate. The planning and execution variables of the movement trajectory were analyzed, and the significance was set at 5%.

RESULTS

Trajectories of the SPSG were slower (p = .010; η2 = 0.22), were less smooth (p = .002; η2 = 0.30), had more directional error (p = .002; η2 = 0.28), and were less accurate (p = .034; η2 = 0.17) than the CTG. The nSPSG and CTG showed similar performance.

CONCLUSIONS

The perception of pain impairs aiming movements performed with the ipsilesional upper limb in individuals with unilateral chronic stroke.

A Novel Endoplasmic Reticulum-Targeted Metal-Organic Framework-Confined Ruthenium (Ru) Nanozyme Regulation of Oxidative Stress for Central Post-Stroke Pain

Central post-stroke pain (CPSP) is a chronic neuropathic pain caused by cerebrovascular lesion or disfunction after stroke. Convincing evidence suggest that excessive reactive oxygen species (ROS), generated matrix metalloproteinase (MMPs) and neuroinflammation are largely involved in the development of pain. In this study, an effective strategy is reported for treating pain hypersensitivity using an endoplasmic reticulum (ER)-targeted metal-organic framework (MOF)-confined ruthenium (Ru) nanozyme. The Ru MOF is coated with a p-dodecylbenzene sulfonamide (p-DBSN) modified liposome with endoplasmic reticulum-targeted function. The experimental results reveals that ROS, Emmprin, MMP-2, and MMP-9 are upregulated in the brain of CPSP mice, along with the elevated expression of inflammation markers such as TNF-α and IL-6. Compared to vehicle, one-time intravenous administration of ER-Ru MOF significantly reduces mechanical hypersensitivity after CPSP for three days. Overall, ER-Ru MOF system can inhibit oxidative stress in the brain tissues of CPSP model, reduce MMPs expression, and suppress neuroinflammation response-induced injury, resulting in satisfactory prevention and effective treatment of CPSP during a hemorrhagic stroke. The ER-Ru MOF is expected to be useful for the treatment of neurological diseases associated with the vicious activation of ROS, based on the generality of the approach used in this study.

Neurophysiological oscillatory markers of hypoalgesia in conditioned pain modulation

Introduction

Conditioned pain modulation (CPM) is an experimental procedure that consists of an ongoing noxious stimulus attenuating the pain perception caused by another noxious stimulus. A combination of the CPM paradigm with concurrent electrophysiological recordings can establish whether an association exists between experimentally modified pain perception and modulations of neural oscillations.

Objectives

We aimed to characterize how CPM modifies pain perception and underlying neural oscillations. We also interrogated whether these perceptual and/or neurophysiological effects are distinct in patients affected by chronic pain.

Methods

We presented noxious electrical stimuli to the right ankle before, during, and after CPM induced by an ice pack placed on the left forearm. Seventeen patients with chronic pain and 17 control participants rated the electrical pain in each experimental condition. We used magnetoencephalography to examine the anatomy-specific effects of CPM on the neural oscillatory responses to the electrical pain.

Results

Regardless of the participant groups, CPM induced a reduction in subjective pain ratings and neural responses (beta-band [15-35 Hz] oscillations in the sensorimotor cortex) to electrical pain.

Conclusion

Our findings of pain-induced beta-band activity may be associated with top-down modulations of pain, as reported in other perceptual modalities. Therefore, the reduced beta-band responses during CPM may indicate changes in top-down pain modulations.

A retrospective examination of pain in acute stroke at hospital discharge

OBJECTIVES

Pain is an overlooked sequela of stroke. Persistent pain after stroke is an underrecognized experience and significantly impacts survivors' function, ability to participate in rehabilitation, and quality of life. The aim of this retrospective, observational study is to examine the incidence of pain at the acute hospitalization period immediately after stroke, to identify the characteristics of those reporting pain at discharge, and to compare pain reporting between stroke and non-stroke hospital controls.

MATERIALS AND METHODS

Using discharge diagnosis, this retrospective review examined self- reports of pain during acute hospitalization for stroke compared to those with COPD (control group) admitted during the same time in the same facilities. Variables of interest included age, gender, body mass index (BMI), length of stay, pain assessment score (numeric rating scale [NRS], behavior pain scale [BPS], and medication administration record pain score total [MAR]), smoking history, prevalence of hypertension and race. 821 subjects were included from a total of three campuses from one large hospital system. 772 subjects were included in the comparative analysis with COPD patients from the same facilities during the same time.

RESULTS

43% of patients diagnosed with stroke reported pain at discharge. For stroke survivors reporting pain at discharge, the average BMI was higher (p=0.009), average arrival NIHSS was higher (p=0.044), and mean hospital length of stay was longer (p<0.001).

CONCLUSIONS

The evidence demonstrated in this study highlights the critical need for the implementation of targeted objective pain assessment and effective pain interventions for stroke survivors beginning at initial hospitalization.

Thermal Grill Illusion in Post-Stroke Patients: Analysis of Clinical Features and Lesion Areas

Purpose

In the thermal grill illusion, participants experience a feeling similar to burning pain. The illusion is induced by simultaneously touching warm and cool stimuli in alternating positions. In post-stroke pain, central sensitization is caused by a variety of factors, including damage to the spinothalamic tract and shoulder pain. Because the thermal grill illusion depends on central mechanisms, it has recently been suggested that it may be a useful indicator of central sensitization. Therefore, we hypothesized that post-stroke patients who are more likely to experience central sensitization may also be more likely to experience a thermal grill sensation of pain and discomfort than the likelihood among those who are less likely to experience central sensitization. However, the effects of the thermal grill illusion in post-stroke patients have not yet been reported. In this pilot study, we conducted the thermal grill illusion procedure in post-stroke patients and analyzed the relationship between clinical somatosensory functions and thermal grill sensations. We also conducted brain imaging analysis to identify brain lesion areas that were associated with thermal grill sensations.

Patients and Methods

Twenty patients (65.7 ± 11.9 years old) with post-stroke patients participated in this study. The thermal grill illusion procedure was performed as follows: patients simultaneously touched eight water-filled copper bars, with the water temperature adjusted to provide alternate warm (40°C) and cold (20°C) stimuli.

Results

Thermal grill sensation of pain and discomfort tended to be associated with the wind-up phenomenon in bedside quantitative sensory testing and thermal grill sensation of discomfort was also related to damage to the thalamic lateral nucleus.

Conclusion

These findings suggest that the thermal grill illusion might measure central sensitization, and that secondary brain hyperactivity might lead to increased thermal grill sensations.

Pain tolerance after stroke: The Tromsø study

BACKGROUND

Stroke lesions might alter pain processing and modulation by affecting the widely distributed network of brain regions involved. We aimed to compare pain tolerance in stroke survivors and stroke-free persons in the general population, with and without chronic pain.

METHODS

We included all participants of the sixth and seventh wave of the population-based Tromsø Study who had been tested with the cold pressor test (hand in cold water bath, 3°C, maximum time 106 s in the sixth wave and 120 s in the seventh) and who had information on previous stroke status and covariates. Data on stroke status were obtained from the Tromsø Study Cardiovascular Disease Register and the Norwegian Stroke Register. Cox regression models were fitted using stroke prior to study attendance as the independent variable, cold pressor endurance time as time variable and hand withdrawal from cold water as event. Statistical adjustments were made for age, sex, diabetes, hypertension, hyperlipidaemia, body mass index and smoking.

RESULTS

In total 21,837 participants were included, 311 of them with previous stroke. Stroke was associated with decreased cold pain tolerance time, with 28% increased hazard of hand withdrawal (hazard ratio [HR] 1.28, 95% CI 1.10-1.50). The effect was similar in participants with (HR 1.28, 95% CI 0.99-1.66) and without chronic pain (HR 1.29, 95% CI 1.04-1.59).

CONCLUSIONS

Stroke survivors, with and without chronic pain, had lower cold pressor pain tolerance, with possible clinical implications for pain in this group.

SIGNIFICANCE

We found lower pain tolerance in participants with previous stroke compared to stroke-free participants of a large, population-based study. The association was present both in those with and without chronic pain. The results may warrant increased awareness by health professionals towards pain experienced by stroke patients in response to injuries, diseases and procedures.

Somatosensory Impairment and Chronic Pain Following Stroke: An Observational Study

BACKGROUND

Chronic pain and somatosensory impairment are common following a stroke. It is possible that an interaction exists between pain and somatosensory impairment and that a change in one may influence the other. We therefore investigated the presence of chronic pain and self-reported altered somatosensory ability in individuals with stroke, aiming to determine if chronic pain is more common in stroke survivors with somatosensory impairment than in those without.

METHODS

Stroke survivors were invited to complete an online survey that included demographics, details of the stroke, presence of chronic pain, and any perceived changes in body sensations post-stroke.

RESULTS

Survivors of stroke (n = 489) completed the survey with 308 indicating that they experienced chronic pain and 368 reporting perceived changes in somatosensory function. Individuals with strokes who reported altered somatosensory ability were more likely to experience chronic pain than those who did not (OR = 1.697; 95% CI 1.585, 2.446). Further, this difference was observed for all categories of sensory function that were surveyed (detection of light touch, body position, discrimination of surfaces and temperature, and haptic object recognition).

CONCLUSIONS

The results point to a new characteristic of chronic pain in strokes, regardless of nature or region of the pain experienced, and raises the potential of somatosensory impairment being a rehabilitation target to improve pain-related outcomes for stroke survivors.

Pressure pain threshold and somatosensory abnormalities in different ages and functional conditions of post-stroke elderly

Background

Somatosensory deficits and abnormal pain sensitivity are highly prevalent among stroke survivors, which negatively impacts their quality of life and recovery process. However, the factors for pressure pain threshold (PPT) and somatosensory abnormalities in post-stroke elderly remain unknown. The aim of this study was to explore the effects of age, side and other functional conditions, such as spasticity and motor functions, on PPT and sensory abnormalities among elderly after stroke.

Methods

The cross-sectional study finally included 43 post-stroke elderly aged over 60 and assessed the PPT of 14 bilateral muscles widely located in the whole body by using a digital force gage. Meanwhile, spasticity, motor function, joint pain and activity of daily living (ADL) were evaluated by the Modified Ashworth scale, Fugl-Meyer, and Barthel Index, respectively. All participants were divided into higher-aged and lower-aged groups based on the median age of all of them.

Results

Higher age tended to be associated with higher sensitivity but not significant except for one upper limb muscle, and the affected side showed significantly higher PPTs than the unaffected side in three out of seven muscles (p < 0.05). Furthermore, the somatosensory abnormalities in the affected side, particularly hypoalgesia, were more frequent in higher-aged than lower-aged patients in most assessed muscles. Meanwhile, patients with spasticity showed more increment of PPTs in affected muscles around the knee joint than patients without spasticity (p < 0.05). Patients with better motor functions, less joint pain and higher ADL performed less bilateral differences of PPTs than other patients in some muscles (p < 0.05).

Conclusions

The age and side differences of mechanical pain sensitivity were found among post-stroke elderly. Older patients show higher sensitivity in both sides compared with the younger ones, and the affected side of the elder shows more somatosensory abnormalities, particularly hypoalgesia, than that of the younger ones. Post-stroke elderly in good functional conditions, such as normal muscle tone, better physical function and daily activities, and less joint pain, seems to have more equal pain sensitivity between both sides than those in poor conditions.

Intra-rater and inter-rater reliability of pressure pain threshold assessment in stroke patients

BACKGROUND

As pain is a common symptom following a stroke, pressure pain threshold (PPT) assessment can be used to evaluate pain status or pain sensitivity of patients. However, the reliability of PPT test in stroke patients is still unknown.

AIM

To examine the intra- and inter-rater reliability of PPT measurements in poststroke survivors and explore their factors.

DESIGN

An observational study.

SETTING

The setting of the study is a rehabilitation hospital.

POPULATION

The population of the study was represented by a total of 54 patients after stroke.

METHODS

The study included 16 measured points on the affected and unaffected sides. PPT was assessed by two raters in turn. Intra- and inter-rater reliability was evaluated by intraclass correlation coefficients (ICC).

RESULTS

All intra-rater (ICC=0.84-0.97) and inter-rater (ICC=0.83-0.95) reliability for PPT assessment were good or excellent in stroke patients. Of the 16 points, 12 showed higher intra-rater ICC values than inter-rater, whereas no evident difference was observed between the affected and unaffected sides. Furthermore, patients who were male, ischemic, or with higher motor function generally performed higher ICC values than those who were female (24 out of 32 results), hemorrhagic (28 out of 32 results), or mobility dysfunction (26 out of 32 results), respectively.

CONCLUSIONS

PPT assessment with good or excellent reliability can be used in stroke patients. Neither of the two sides (affected or unaffected) affects PPT reliability, and intra-rater reliability is better than inter-rater reliability. In addition, gender, stroke type, and motor function can affect the reliability of measuring mechanical pain threshold in poststroke survivors.

CLINICAL REHABILITATION IMPACT

The pressure algometer can be used as a reliable and portable tool to assess the mechanical pain tolerance and sensory function in stroke patients in clinics.

Conditioned pain modulation is more efficient in patients with painful diabetic polyneuropathy than those with nonpainful diabetic polyneuropathy

ABSTRACT

Endogenous pain modulation, as tested by the conditioned pain modulation (CPM) protocol, is typically less efficient in patients with chronic pain compared with healthy controls. We aimed to assess whether CPM is less efficient in patients with painful diabetic polyneuropathy (DPN) compared with those with nonpainful DPN. Characterization of the differences in central pain processing between these 2 groups might provide a central nervous system explanation to the presence or absence of pain in diabetic neuropathy in addition to the peripheral one. Two hundred seventy-one patients with DPN underwent CPM testing and clinical assessment, including quantitative sensory testing. Two modalities of the test stimuli (heat and pressure) conditioned to cold noxious water were assessed and compared between patients with painful and nonpainful DPN. No significant difference was found between the groups for pressure pain CPM; however, patients with painful DPN demonstrated unexpectedly more efficient CPMHEAT (-7.4 ± 1.0 vs -2.3 ± 1.6; P = 0.008). Efficient CPMHEAT was associated with higher clinical pain experienced in the 24 hours before testing (r = -0.15; P = 0.029) and greater loss of mechanical sensation (r = -0.135; P = 0.042). Moreover, patients who had mechanical hypoesthesia demonstrated more efficient CPMHEAT (P = 0.005). More efficient CPM among patients with painful DPN might result from not only central changes in pain modulation but also from altered sensory messages coming from tested affected body sites. This calls for the use of intact sites for proper assessment of pain modulation in patients with neuropathy.

Peripheral Nerve Stimulation for the Treatment of Hemiplegic Shoulder Pain

Hemiplegic shoulder pain (HSP) is a common comorbidity affecting stroke survivors. It can lead to chronic pain in a significant portion of patients. Prompt recognition and treatment may lead to improved outcomes, though it can be very challenging to treat. Peripheral nerve stimulation (PNS) has shown significant promise as a treatment modality for HSP. We present an interesting case of a patient with debilitating HSP that was unresponsive to a variety of medications and prior neuromodulation therapies. We report our experience utilizing the SPRINT PNS system and our outcomes treating a patient with refractory HSP.

The Effects of Gender, Functional Condition, and ADL on Pressure Pain Threshold in Stroke Patients

Background

Somatosensory impairments and pain are common symptoms following stroke. However, the condition of perception and pain threshold for pressure stimuli and the factors that can influence this in individuals with stroke are still unclear. This study aimed to investigate the gender differences in pressure pain threshold (PPT) and positive somatosensory signs for pressure stimuli, and explore the effects of joint pain, motor function, and activities of daily living (ADL) on pain threshold in post-stroke patients.

Design

A cross-sectional study.

Methods

A total of 60 participants with stroke were recruited, and their pain condition, motor functions, and ADL were evaluated by the Fugl-Meyer assessment of joint pain scale, motor function scale, and Barthel index, respectively. PPTs in eight tested points at the affected and unaffected sides were assessed.

Results

Significant differences in PPTs were found between male and female patients in all measured muscles (p < 0.05). Positive somatosensory signs for pressure stimuli, including hypoalgesia and hyperalgesia, were frequently found at the affected side, particularly in the extremity muscles, but such signs were not significantly influenced by gender (p > 0.05). More equal PPTs between both sides and relatively lower PPTs at the affected side in the trunk and medial gastrocnemius muscles (p < 0.05) were observed in patients with less pain, better motor functions, and ADL.

Conclusion

Gender differences widely exist in post-stroke survivors either at the affected or unaffected side, which are multifactorial. Sensory loss and central and/or peripheral sensitization, such as hypoalgesia and hyperalgesia for pressure stimuli, caused by a brain lesion are common signs in male and female stroke patients. Moreover, patients who are in a better condition show a more symmetrical pain sensitivity between both sides in the trunk and in female lower extremities, indicating the bidirectional improvement of somatosensory abnormalities caused by a possible neural plasticity.

Peripherally Induced Reconditioning of the Central Nervous System: A Proposed Mechanistic Theory for Sustained Relief of Chronic Pain with Percutaneous Peripheral Nerve Stimulation

Peripheral nerve stimulation (PNS) is an effective tool for the treatment of chronic pain, although its efficacy and utilization have previously been significantly limited by technology. In recent years, purpose-built percutaneous PNS devices have been developed to overcome the limitations of conventional permanently implanted neurostimulation devices. Recent clinical evidence suggests clinically significant and sustained reductions in pain can persist well beyond the PNS treatment period, outcomes that have not previously been observed with conventional permanently implanted neurostimulation devices. This narrative review summarizes mechanistic processes that contribute to chronic pain, and the potential mechanisms by which selective large diameter afferent fiber activation may reverse these changes to induce a prolonged reduction in pain. The interplay of these mechanisms, supported by data in chronic pain states that have been effectively treated with percutaneous PNS, will also be discussed in support of a new theory of pain management in neuromodulation: Peripherally Induced Reconditioning of the Central Nervous System (CNS).

Association between Physiological and Subjective Aspects of Pain and Disability in Post-Stroke Patients with Shoulder Pain: A Cross-Sectional Study

Background: Patients often experience pain as a result of a stroke. However, the mechanism of this pain remains uncertain. Our aim was to investigate the relationship between pressure pain thresholds (PPTs) and disability pain in patients with hemiplegic shoulder pain (HSP). Methods: Twenty-six post-stroke patients (age 53.35 ± 13.09 years) and healthy controls (54.35 ± 12.37 years) participated. We investigated spontaneous shoulder pain, disability pain perception through the shoulder pain and disability index (SPADI), and the PPTs over joint C5–C6, upper trapezius, deltoid, epicondyle, second metacarpal, and tibialis anterior, bilaterally. Results: The analysis of variance (ANOVA) showed significant differences in pain between groups (p < 0.001) and differences in the SPADI (p < 0.001) between groups but not between sides for PPTs over deltoid (group: p = 0.007; side: p = 0.750), epicondyle (group: p = 0.001; side: p = 0.848), and tibialis anterior (group: p < 0.001; side: p = 0.932). Pain in the affected arm was negatively associated with PPTs over the affected epicondyle (p = 0.003) and affected tibialis anterior (p = 0.009). Pain (SPADI) appeared negatively correlated with PPTs over the affected epicondyle (p = 0.047), and disability (SPADI) was negatively associated with PPTs over the affected tibialis anterior (p = 0.041). Conclusions: Post-stroke patients showed a relationship between widespread pressure pain hypersensitivity with lower PPT levels and pain disability perception, suggesting a central sensitization mediated by bilateral and symmetric pain patterns.

The effect of electrical stimulation on impairment of the painful post-stroke shoulder

Background: Transcutaneous electrical nerve stimulation (TENS) and transcutaneous neuromuscular electrical stimulation (t-NMES) are commonly used therapies in the treatment of chronic hemiplegic shoulder pain. These treatments are often utilized during physical or occupational therapy sessions, yet research into the acute analgesic effects of TENS and t-NMES on hemiplegic shoulder pain and use during therapy is limited. Objective: To compare the acute effects of transcutaneous electrical nerve stimulation (TENS), transcutaneous neuromuscular electrical stimulation (t-NMES), and no stimulation on pain-free passive range of motion of the shoulder in subjects with hemiplegic shoulder pain. Methods: Prospective cohort study of 10 subjects randomly treated with t-NMES, TENS, and one non-stimulation experimental condition. Pain-free passive external rotation and abduction range of motion of the affected shoulder were measured during stimulation. Results: There was not a significant within-subject difference in pain-free range of motion for external rotation or abduction. Subject to subject differences explained the majority of the variability in pain-free range of motion. Conclusion: This pilot study is the first to measure pain-free passive range of motion during electrical stimulation. Our findings demonstrate the lack of an acute effect of TENS and t-NMES on pain reduction.

Post-stroke shoulder pain subtypes classifying criteria: towards a more specific assessment and improved physical therapeutic care

BACKGROUND

Post-stroke Shoulder Pain (PSSP) is a common stroke-related syndrome that prolongs hospitalization and diminishes quality of life. PSSP studies were unsuccessful in clarifying pathophysiological mechanisms. Therefore, cohort's studies with greater variety of the sample and larger follow-up period could provide additional clinical data and may improve medical care.

OBJECTIVE

To classify people with PSSP and identify intergroup clinical differences, providing additional data useful for therapeutic care planning.

METHODS

One thousand individuals with stroke were selected from all levels of one health Area and followed up during one year. Demographic data, stroke clinical characteristics, stroke-related symptoms and rehabilitation parameters were collected. The shoulder muscle impairment was used to group participants into three clinical profiles: severe muscular impairment, moderate muscular impairment and low muscular impairment groups.

RESULTS

A total of 119 individuals were diagnosed with PSSP. The suggested classification criteria showed two groups that differed significantly in relation to the onset and duration of PSSP, presence of sensory and speech impairment, and spasticity. The outcomes did not firmly support the existence of a third suggested PSSP subtype.

CONCLUSIONS

PSSP may vary in onset, clinical manifestations, severity and syndrome duration. These results highlight the course of different clinical profiles and require multidisciplinary management approaches.

Acupuncture-Analgesia-Mediated Alleviation of Central Sensitization

Pain can trigger central amplification called central sensitization, which ultimately results in hyperalgesia and/or allodynia. Many reports have showed acupuncture has an analgesic effect. We searched the related article on PubMed database and Cochrane database to discover central sensitization pathway in acupuncture analgesia. We summarized that acupuncture enhances the descending inhibitory effect and modulates the feeling of pain, thus modifying central sensitization. The possible mechanisms underlying the analgesic effects of acupuncture include segmental inhibition and the activation of the endogenous opioid, adrenergic, 5-hydroxytryptamine, and N-methyl-D-aspartic acid, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate pathways. Moreover, acupuncture can locally reduce the levels of inflammatory mediators. In clinical settings, acupuncture can be used to treat headache, neuropathic pain, low back pain, osteoarthritis, and irritable bowel syndrome. These mechanisms of acupuncture analgesia may be involved in the alleviation of central sensitization.

Pain management strategies among persons with long-term shoulder pain after stroke - a qualitative study

OBJECTIVE:

To explore strategies that persons with persistent shoulder pain after stroke use to manage their pain in daily life.

DESIGN:

A qualitative study using semi-structured face-to-face interviews, analysed by content analysis.

SETTING:

A university hospital.

SUBJECTS:

Thirteen community-dwelling persons (six women; median age: 65 years; range 57-77) with shoulder pain after stroke were interviewed median two years after the pain onset.

RESULTS:

An overall theme 'Managing shoulder pain by adopting various practical and cognitive strategies' emerged from the analysis. Three categories were identified: (1) practical modifications to solve daily life problems; (2) changed movement patterns and specific actions to mitigate the pain, by non-painful movements, avoidance of pain-provoking activities and various pain distracting activities and (3) learned how to deal with the pain mentally. Several strategies were used simultaneously and they were experienced successful to various degrees.

CONCLUSION:

The findings in the present study indicate that persons with persistent shoulder pain after stroke use both practical and cognitive strategies to manage their pain.

Pain Modulation: From Conditioned Pain Modulation to Placebo and Nocebo Effects in Experimental and Clinical Pain

Accumulating evidence reveal important applications of endogenous pain modulation assessment in healthy controls and in patients in clinical settings, as dysregulations in the balance of pain modulatory circuits may facilitate pain and promote chronification of pain. This article reviews data on pain modulation, focusing on the mechanisms and translational aspects of pain modulation from conditioned pain modulation (CPM) to placebo and nocebo effects in experimental and clinical pain. The specific roles of expectations, learning, neural and neurophysiological mechanisms of the central nervous system are briefly reviewed herein. The interaction between CPM and placebo systems in pain inhibitory pathways is highly relevant in the clinic and in randomized controlled trials yet remains to be clarified. Examples of clinical implications of CPM and its relationship to placebo and nocebo effects are provided. A greater understanding of the role of pain modulation in various pain states can help characterize the manifestation and development of chronic pain and assist in predicting the response to pain-relieving treatments. Placebo and nocebo effects, intrinsic to every treatment, can be used to develop personalized therapeutic approaches that improve clinical outcomes while limiting unwanted effects.

Short- and medium-term effect of kinesio taping or electrical stimulation in hemiplegic shoulder pain prevention: A randomized controlled pilot trial

OBJECTIVE

To compare the short and medium-term effectiveness of combining Kinesio Tape (KT) or neuromuscular electrical stimulation (NMES) with a conventional approach to prevent shoulder pain after stroke.

METHODS

Thirty-one first-time stroke survivors (58.06% females) were recruited and randomly assigned to one group; Control (n = 10), KT (n = 11), or NMES (n = 10). Ten of all participants were lost during follow-up because of death or a second stroke. The control group underwent conventional treatment (careful shoulder handling and daily mobilizations). This approach was combined with KT or NMES over deltoid muscles in the KT and NMES groups respectively. Measurements were taken at baseline, and at weeks 1, 2, 3, 4, 12, and 24 post-stroke. Data collected included self-perceived shoulder pain (Visual Analogue Scale), disability (Barthel Index and Berg scale), and upper limb function (Action Research Arm test).

RESULTS

In all groups, shoulder pain did not appear during the first month (p < 0.001), but increased afterwards. In the between-groups analysis, all groups similarly improved disability and function, and no significant differences were observed for any measure (p > 0.05).

CONCLUSION

The combination of KT or NMES with conventional treatment is no superior to conventional treatment alone to prevent hemiplegic shoulder pain.

Does conditioned pain modulation predict the magnitude of placebo effects in patients with neuropathic pain?

BACKGROUND

Conditioned pain modulation (CPM) is a validated measure of the function of endogenous pain inhibitory pathways. Placebo effects reflect top-down inhibitory modulation of pain. CPM and placebo effects are both influenced by expectations, albeit to varying degrees, and are related to neurotransmitter systems such as the endogenous opioid system, and it can be speculated that CPM responses are positively associated with the magnitude of placebo effects. Yet, no studies have tested this.

METHODS

The study included 19 patients with neuropathic pain. CPM was quantified as the difference in pressure pain threshold (PPT) as measured at the middle deltoid muscle before and after 5-min exposure to the cold pressor test (CPT) (conditioning pain stimulus). Placebo effects were tested via open and hidden applications of the pain-relieving agent lidocaine (2 mL) using a disinfection napkin controlled for no treatment.

RESULTS

The mean (SD) PPT was 668.7 (295.7) kPa before and 742.3 (370.8) kPa after the CPT. The mean (SD) CPM response was -73.6 (214.0) kPa corresponding to an 11% increase in PPT, reflecting a normally functioning endogenous pain modulatory system. Large and significant placebo effects were observed in ongoing neuropathic pain intensity (p = 0.002). The CPM response did not predict the magnitude of the placebo effect (p = 0.765). Moreover, there were no interaction effects for the moderator variables: clinical pain level (p = 0.136), age (p = 0.347) and gender (p = 0.691).

CONCLUSIONS

Conditioned pain modulation and placebo effects do not seem to be associated in patients with neuropathic pain.

SIGNIFICANCE

Conditioned pain modulation and placebo effects are endogenous pain-modulating phenomena that are influenced by some of the same mechanisms. This study suggests that CPM and placebo effects in neuropathic pain are independent phenomena that may be mediated by different mechanisms.

Fully Implantable Peripheral Nerve Stimulation for Hemiplegic Shoulder Pain: A Multi-Site Case Series With Two-Year Follow-Up

OBJECTIVE

To explore the feasibility and safety of a single-lead, fully implantable peripheral nerve stimulation system for the treatment of chronic shoulder pain in stroke survivors.

PARTICIPANTS

Participants with moderate to severe shoulder pain not responsive to conservative therapies for six months.

METHODS

During the trial phase, which included a blinded sham introductory period, a percutaneous single-lead peripheral nerve stimulation system was implanted to stimulate the axillary nerve of the affected shoulder. After a three-week successful trial, participants received an implantable pulse generator with an electrode placed to stimulate the axillary nerve of the affected shoulder. Outcomes included pain, pain interference, pain-free external rotation range of motion, quality of life, and safety. Participants were followed for 24 months.

RESULTS

Twenty-eight participants underwent trial stimulation and five participants received an implantable pulse generator. The participants who received the implantable generator experienced an improvement in pain severity (p = 0.0002). All five participants experienced a 50% or greater pain reduction at 6 and 12 months, and four experienced at least a 50% reduction at 24 months. There was an improvement in pain interference (p < 0.0001). There was an improvement in pain-free external ROM (p = 0.003). There were no serious adverse events related to the device or to the procedure.

CONCLUSIONS

This case series demonstrates the safety and efficacy of a fully implantable axillary PNS system for chronic HSP. Participants experienced reduction in pain, reduction in pain interference, and improved pain-free external rotation ROM. There were no serious adverse events associated with the system or the procedure.

A novel dual-wavelength laser stimulator to elicit transient and tonic nociceptive stimulation

This study aimed to develop a new laser stimulator to elicit both transient and sustained heat stimulation with a dual-wavelength laser system as a tool for the investigation of both transient and tonic experimental models of pain. The laser stimulator used a 980-nm pulsed laser to generate transient heat stimulation and a 1940-nm continuous-wave (CW) laser to provide sustained heat stimulation. The laser with 980-nm wavelength can elicit transient pain with less thermal injury, while the 1940-nm CW laser can effectively stimulate both superficial and deep nociceptors to elicit tonic pain. A proportional integral-derivative (PID) temperature feedback control system was implemented to ensure constancy of temperature during heat stimulation. The performance of this stimulator was evaluated by in vitro and in vivo animal experiments. In vitro experiments on totally 120 specimens fresh pig skin included transient heat stimulation by 980-nm laser (1.5 J, 10 ms), sustained heat stimulation by 1940-nm laser (50-55 °C temperature control mode or 1.5 W, 5 min continuous power supply), and the combination of transient/sustained heat stimulation by dual lasers (1.5 J, 10 ms, 980-nm pulse laser, and 1940-nm laser with 50-55 °C temperature control mode). Hemoglobin brushing and wind-cooling methods were tested to find better stimulation model. A classic tail-flick latency (TFL) experiment with 20 Wistar rats was used to evaluate the in vivo efficacy of transient and tonic pain stimulation with 15 J, 100 ms 980-nm single laser pulse, and 1.5 W constant 1940-nm laser power. Ideal stimulation parameters to generate transient pain were found to be a 26.6 °C peak temperature rise and 0.67 s pain duration. In our model of tonic pain, 5 min of tonic stimulation produced a temperature change of 53.7 ± 1.3 °C with 1.6 ± 0.2% variation. When the transient and tonic stimulation protocols were combined, no significant difference was observed depending on the order of stimuli. Obvious tail-flick movements were observed. The TFL value of transient pain was 3.0 ± 0.8 s, and it was 4.4 ± 1.8 s for tonic pain stimulation. This study shows that our novel design can provide effective stimulation of transient pain and stable tonic pain. Furthermore, it can also provide a reliable combination of transient and consistent stimulations for basic studies of pain perception.

Musculoskeletal and central pain at 1 year post-stroke: associated factors and impact on quality of life

BACKGROUND AND PURPOSE

Pain is common in post-stroke patients and has been shown to be associated with depression, fatigue, and decreased quality of life (QOL). However, studies examining different types of post-stroke pain are scarce. We investigated differences in the related factors and their QOL impacts between musculoskeletal pain (MSP) and central post-stroke pain (CPSP).

METHODS

We assessed 364 consecutive stroke patients who were admitted to Asan Medical Center and contacted 12 months after stroke onset. We categorized pain and paresthesia as MSP, CPSP, combined pain, or other pain. Post-stroke depression (Beck Depression Inventory), fatigue (Fatigue Severity Scale), sleep disturbance (Verran Snyder-Halpern scale), social support (ENRICHED Social Support Instrument), and QOL (Medical Outcome Study 36-Item Short Form) were assessed.

RESULTS

Of the 364 patients analyzed, 135 (37.1%) had pain, 78 (21.4%) had MSP, 22 (6.0%) had CPSP, 16 (4.4%) had combined pain, and 19 (5.2%) had other pain. In multivariate analyses, CPSP was related to modified Rankin scale (P=.004), sensory dysfunction (P<.001), thalamus lesion (P=.001), medulla lesion (P=.007), and fatigue (P=.026). MSP was related to motor dysfunction (P<.001) and fatigue (P=.003). QOL varied among groups with different types of pain (P<.001) and was the poorest in patients with combined pain.

CONCLUSIONS

Pain is common 12 months post-stroke. The factors associated with CPSP and MSP differ, but are both closely associated with fatigue rather than depression. QOL is the poorest in patients with combined pain. Management of pain and fatigue may be important for improving the QOL in stroke patients.

Shoulder pain after stroke - experiences, consequences in daily life and effects of interventions: a qualitative study

PURPOSE

To describe experiences of shoulder pain after stroke, how pain affects daily life and perceived effects of interventions.

METHOD

A qualitative interview study including 13 community-dwelling persons (six women; median age 65 years) with persistent shoulder pain after stroke.

RESULTS

Three categories emerged from the content analysis. In "Multiple pain characteristics" an insidious pain onset was reported. The pain existed both day and night and could be located around the shoulder girdle but also have radiation to the arm and hand. An explanation of the pain was seldom given. In "Limitations caused by the pain" it was described how the pain negatively influenced personal care, household activities and leisure, but also could lead to emotional reactions. In "Multiple pain interventions with various effects" a variety of interventions were described. Self-management interventions with gentle movements were perceived most effective. A restraint attitude to pain medication due to side effects was reported.

CONCLUSIONS

Shoulder pain after stroke can lead to a variety of pain characteristics. As the pain is complex and may affect many important areas in a person's life, multidisciplinary rehabilitation interventions are important. Implications for rehabilitation Shoulder pain after stroke can lead to a variety of pain characteristics with radiation to the arm and hand Shoulder pain often influence personal care, household activities and leisure negatively, which may lead to emotional reactions Self-management interventions with gentle movements are perceived most effective As the shoulder pain after stroke is complex, interventions by a multidisciplinary team may be needed.

The Effect of Peripheral Nerve Stimulation on Shoulder Biomechanics: A Randomized Controlled Trial in Comparison to Physical Therapy

OBJECTIVE

To establish the effects on shoulder biomechanics from a peripheral nerve stimulation (PNS) treatment compared to physical therapy (PT) in stroke survivors with chronic hemiplegic shoulder pain.

DESIGN

Single-site, pilot, randomized controlled trial for adults with chronic shoulder pain after stroke. Participants were randomized to receive a 3-week treatment of single-lead PNS or physical therapy (PT). The outcomes included isometric shoulder abduction strength, pain-free shoulder external rotation range of motion (ROM), delay in initiation and termination of shoulder abduction electromyogram (EMG) activity, and the Fugl-Meyer Motor Assessment (upper extremity section). Outcomes were measured at baseline, and at weeks 1, 4, 12, and 16.

RESULTS

Twenty-five participants were recruited, 13 to PNS and 12 to PT. There were significant improvements for both PNS and PT in maximum isometric shoulder abduction strength, pain-free external rotation ROM, and Fugl-Meyer Motor Assessment. There were no significant changes in delay of initiation or termination of deltoid EMG with either treatment.

CONCLUSIONS

Both PNS and PT are capable of improving shoulder biomechanics in those with HSP, though changes in biomechanics alone do not account for the greater pain relief associated with PNS than PT.

Guidelines for Adult Stroke Rehabilitation and Recovery: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

PURPOSE

The aim of this guideline is to provide a synopsis of best clinical practices in the rehabilitative care of adults recovering from stroke.

METHODS

Writing group members were nominated by the committee chair on the basis of their previous work in relevant topic areas and were approved by the American Heart Association (AHA) Stroke Council's Scientific Statement Oversight Committee and the AHA's Manuscript Oversight Committee. The panel reviewed relevant articles on adults using computerized searches of the medical literature through 2014. The evidence is organized within the context of the AHA framework and is classified according to the joint AHA/American College of Cardiology and supplementary AHA methods of classifying the level of certainty and the class and level of evidence. The document underwent extensive AHA internal and external peer review, Stroke Council Leadership review, and Scientific Statements Oversight Committee review before consideration and approval by the AHA Science Advisory and Coordinating Committee.

RESULTS

Stroke rehabilitation requires a sustained and coordinated effort from a large team, including the patient and his or her goals, family and friends, other caregivers (eg, personal care attendants), physicians, nurses, physical and occupational therapists, speech-language pathologists, recreation therapists, psychologists, nutritionists, social workers, and others. Communication and coordination among these team members are paramount in maximizing the effectiveness and efficiency of rehabilitation and underlie this entire guideline. Without communication and coordination, isolated efforts to rehabilitate the stroke survivor are unlikely to achieve their full potential.

CONCLUSIONS

As systems of care evolve in response to healthcare reform efforts, postacute care and rehabilitation are often considered a costly area of care to be trimmed but without recognition of their clinical impact and ability to reduce the risk of downstream medical morbidity resulting from immobility, depression, loss of autonomy, and reduced functional independence. The provision of comprehensive rehabilitation programs with adequate resources, dose, and duration is an essential aspect of stroke care and should be a priority in these redesign efforts. (Stroke.2016;47:e98-e169. DOI: 10.1161/STR.0000000000000098.).

Prevalence and determinants of pain in the ipsilateral upper limb of stroke patients

This study investigated the prevalence of pain in the ipsilateral upper-limb in stroke patients. 229 stroke patients (133 men, 96 women; M age = 59.0 yr., SD = 12.4) were assessed with the Pain Behaviors Scales and their motor weakness was measured with the Motricity Index. Results indicated that over 27% of patients experienced pain in at least one joint of the ipsilateral upper limb. Shoulder pain was the most common. Further analysis indicated that the occurrence of pain in the ipsilateral upper limb was higher among women, among patients who used a cane, and among patients with a greater weakness of the affected lower limb.

Conditioned pain modulation: a predictor for development and treatment of neuropathic pain

Psychophysical evaluation of endogenous pain inhibition via conditioned pain modulation (CPM) represents a new generation of laboratory tests for pain assessment. In this review we discuss recent findings on CPM in neuropathic pain and refer to psychophysical, neurophysiological, and methodological aspects of its clinical implications. Typically, chronic neuropathic pain patients express less efficient CPM, to the extent that incidence of acquiring neuropathic pain (e.g. post-surgery) and its intensity can be predicted by a pre-surgery CPM assessment. Moreover, pre-treatment CPM evaluation may assist in the correct choice of serotonin-noradrenalin reuptake inhibitor analgesic agents for individual patients. Evaluation of pain modulation capabilities can serve as a step forward in individualizing pain medicine.

Poststroke shoulder pain and its association with upper extremity sensorimotor function, daily hand activities, perceived participation, and life satisfaction

OBJECTIVE

To assess the differences in upper extremity sensorimotor function, daily hand activities, and perceived participation and life satisfaction between individuals with and without poststroke shoulder pain (PSSP), and to determine how PSSP is associated with these variables.

DESIGN

A cross-sectional study of a convenience sample.

PARTICIPANTS

Forty-nine community-dwelling individuals (mean ± standard deviation [SD] age, 64 ± 9 years), 24 with PSSP and 25 without (non-PSSP) were assessed, in mean ± SD 15 ± 8 months after stroke.

METHODS

Upper extremity sensorimotor function was assessed, and daily hand activities, perceived participation, and life satisfaction were reported. Demographics were described, and shoulder pain characteristics were recorded in the PSSP group. Between-group differences and regression analyses were conducted.

RESULTS

The PSSP group had significantly decreased passive shoulder abduction (P = .001) and upper extremity motor function (P = .03) in comparison with the non-PSSP group, but there were no significant differences between the groups in daily hand activities, perceived participation, or life satisfaction. In the multivariate analyses, PSSP (odds ratio [OR] 4.42 [95% confidence interval (CI), 1.21-16.24]; P = .03) and proprioception (OR 10.28 [95% CI, 1.1-96.01]; P = .04) were associated with upper extremity motor function, whereas perceived participation was associated with life satisfaction (OR 1.08 [95% CI, 1.03-1.13]; P = .002). Passive shoulder abduction, resistance to passive movements, and proprioception explained 45% of variance of daily hand activities, whereas daily hand activities, vocational situation, and gender explained 40% of variance of perceived participation.

CONCLUSIONS

This cross-sectional study indicated that there is an association between PSSP and upper extremity motor function, whereas the association between PSSP, daily hand activities, perceived participation, and life satisfaction is less clear. PSSP is commonly described as a severely disabling condition, but our results imply that, in individuals with mild-to-moderate upper extremity paresis, it may not have a great impact on their life situation.

Peripheral nerve stimulation compared with usual care for pain relief of hemiplegic shoulder pain: a randomized controlled trial

OBJECTIVE

This study sought to establish the efficacy of single-lead, 3-wk peripheral nerve stimulation (PNS) therapy for pain reduction in stroke survivors with chronic hemiplegic shoulder pain.

DESIGN

This study is a single-site, pilot, randomized controlled trial of adults with chronic shoulder pain after stroke. Participants were randomized to receive a 3-wk treatment of single-lead PNS or usual care. The primary outcome was the worst pain in the last week (Brief Pain Inventory, Short Form, question 3) measured at baseline and weeks 1, 4, 12, and 16. The secondary outcomes included pain interference (Brief Pain Inventory, Short Form, question 9), pain measured by the ShoulderQ Visual Graphic Rating Scales, and health-related quality-of-life (Short-Form 36 version 2).

RESULTS

Twenty-five participants were recruited, 13 to PNS and 12 to usual care. There was a significantly greater reduction in pain for the PNS group compared with the controls, with significant differences at 6 and 12 wks after treatment. Both PNS and usual care were associated with significant improvements in pain interference and physical health-related quality-of-life.

CONCLUSIONS

Short-term PNS is a safe and efficacious treatment of shoulder pain. Pain reduction is greater compared with usual care and is maintained for at least 12 wks after treatment.

Central hypersensitivity in chronic hemiplegic shoulder pain

OBJECTIVE

This study aimed to examine the association of hemiplegic shoulder pain (HSP) with central hypersensitivity through pressure-pain thresholds (PPTs) in healthy, distant tissues.

DESIGN

This study is a cross-sectional study. A total of 40 patients (n = 20, HSP; n = 20, stroke without HSP) were enrolled in this study. PPTs were measured at the affected deltoid and the contralateral deltoid and the tibialis anterior using a handheld algometer. Differences in PPTs were analyzed by Wilcoxon's rank-sum test and with linear regression analysis, controlling for sex, a known confounder of PPTs.

RESULTS

The subjects with HSP had lower local PPTs than did the control subjects who have had a stroke when comparing the painful shoulders with the dominant shoulders of the controls and comparing the nonpainful shoulder and the tibialis anterior with the nondominant side of the controls. Similarly, those with HSP had lower PPTs compared with the controls in contralesional-to-contralesional comparisons as well as ipsilesional-to-ipsilesional comparisons.

CONCLUSIONS

The subjects with HSP have lower local and distal PPTs than the subjects without HSP. This study suggests that chronic shoulder pain may be associated with widespread central hypersensitivity, which has been previously found to be associated with other chronic pain syndromes. This further understanding can then help develop better treatment options for those with this HSP.

Different symptoms of neuropathic pain can be induced by different degrees of compressive force on the C7 dorsal root of rats

BACKGROUND CONTEXT

Neuropathic pain after nerve injuries is characterized by positive and negative sensory symptoms and signs. The extent of sensory fiber loss after nerve injuries has been demonstrated to correlate with symptoms of neuropathic pain by quantitative sensory testing and confirmed by biopsies of small nerve fibers. However, the relationship between the pathologic changes of large nerves on injuries and resulting pain symptoms remains unclear.

PURPOSE

To investigate the relationship between the extent of dorsal root injury and resulting symptoms of neuropathic pain.

STUDY DESIGN

Nerve injury and assessment of the following pain-related behaviors and neuropathologic changes.

METHODS

A total of 24 adult male Sprague-Dawley rats weighing 250 to 300 g were randomly divided into three groups (n=8 each): sham group operated on but without nerve compression, 70 gf group, and 180 gf group; a compression force of 70 or 180 g was applied to the right C7 dorsal root, separately. Threshold thermal and mechanical pains were measured before surgery (baseline) and on the first, third, fifth, and seventh day after surgery. On the seventh day after surgery, all rats were killed, and the structural alterations of nerve fibers within the compressed areas were examined.

RESULTS

A compression force of 70 g resulted in hyperalgesia, whereas a compression force of 180 g induced hypoalgesia in the ipsilateral forepaw in response to both mechanical and thermal stimulations within 7 days after injury. Light microscopy and electron microscopy revealed a mild to moderate sensory fiber loss after 70-gf compression and a more severe sensory fiber loss after 180-gf compression.

CONCLUSIONS

Transient injuries on sensory fibers can produce either positive or negative symptoms of neuropathic pain, and the different extent of sensory fiber loss after different degrees of injuries might account for the varied resulting symptoms of neuropathic pain.

Central poststroke pain: somatosensory abnormalities and the presence of associated myofascial pain syndrome

Background

Central post-stroke pain (CPSP) is a neuropathic pain syndrome associated with somatosensory abnormalities due to central nervous system lesion following a cerebrovascular insult. Post-stroke pain (PSP) refers to a broader range of clinical conditions leading to pain after stroke, but not restricted to CPSP, including other types of pain such as myofascial pain syndrome (MPS), painful shoulder, lumbar and dorsal pain, complex regional pain syndrome, and spasticity-related pain. Despite its recognition as part of the general PSP diagnostic possibilities, the prevalence of MPS has never been characterized in patients with CPSP patients. We performed a cross-sectional standardized clinical and radiological evaluation of patients with definite CPSP in order to assess the presence of other non-neuropathic pain syndromes, and in particular, the role of myofascial pain syndrome in these patients.

Methods

CPSP patients underwent a standardized sensory and motor neurological evaluation, and were classified according to stroke mechanism, neurological deficits, presence and profile of MPS. The Visual Analogic Scale (VAS), McGill Pain Questionnaire (MPQ), and Beck Depression Scale (BDS) were filled out by all participants.

Results

Forty CPSP patients were included. Thirty-six (90.0%) had one single ischemic stroke. Pain presented during the first three months after stroke in 75.0%. Median pain intensity was 10 (5 to 10). There was no difference in pain intensity among the different lesion site groups. Neuropathic pain was continuous-ongoing in 34 (85.0%) patients and intermittent in the remainder. Burning was the most common descriptor (70%). Main aggravating factors were contact to cold (62.5%). Thermo-sensory abnormalities were universal. MPS was diagnosed in 27 (67.5%) patients and was more common in the supratentorial extra-thalamic group (P <0.001). No significant differences were observed among the different stroke location groups and pain questionnaires and scales scores. Importantly, CPSP patients with and without MPS did not differ in pain intensity (VAS), MPQ or BDS scores.

Conclusions

The presence of MPS is not an exception after stroke and may present in association with CPSP as a common comorbid condition. Further studies are necessary to clarify the role of MPS in CPSP.