Widespread Pressure Pain Hypersensitivity in Patients With Multiple Sclerosis With and Without Pain as Sign of Central Sensitization

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.

Symptom Interconnectivity in Multiple Sclerosis: A Narrative Review of Potential Underlying Biological Disease Processes

Introduction

Fatigue, cognitive impairment, depression, and pain are highly prevalent symptoms in multiple sclerosis (MS). These often co-occur and may be explained by a common etiology. By reviewing existing literature, we aimed to identify potential underlying biological processes implicated in the interconnectivity between these symptoms.

Methods

A literature search was conducted to identify articles reporting research into the biological mechanisms responsible for the manifestation of fatigue, cognitive impairment, depression, and pain in MS. PubMed was used to search for articles published from July 2011 to July 2021. We reviewed and assessed findings from the literature to identify biological processes common to the symptoms of interest.

Results

Of 693 articles identified from the search, 252 were selected following screening of titles and abstracts and assessing reference lists of review articles. Four biological processes linked with two or more of the symptoms of interest were frequently identified from the literature: (1) direct neuroanatomical changes to brain regions linked with symptoms of interest (e.g., thalamic injury associated with cognitive impairment, fatigue, and depression), (2) pro-inflammatory cytokines associated with so-called ‘sickness behavior,’ including manifestation of fatigue, transient cognitive impairment, depression, and pain, (3) dysregulation of monoaminergic pathways leading to depressive symptoms and fatigue, and (4) hyperactivity of the hypothalamic–pituitary-adrenal (HPA) axis as a result of pro-inflammatory cytokines promoting the release of brain noradrenaline, serotonin, and tryptophan, which is associated with symptoms of depression and cognitive impairment.

Conclusion

The co-occurrence of fatigue, cognitive impairment, depression, and pain in MS appears to be associated with a common set of etiological factors, namely neuroanatomical changes, pro-inflammatory cytokines, dysregulation of monoaminergic pathways, and a hyperactive HPA axis. This association of symptoms and biological processes has important implications for disease management strategies and, eventually, could help find a common therapeutic pathway that will impact both inflammation and neuroprotection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00368-2.

Unique features of central neuropathic pain in multiple sclerosis: Results of a cluster analysis

Background

Central neuropathic pain (CNP) is an excruciating condition, prevalent in up to a third of patients with multiple sclerosis (MS). Identifying CNP among MS patients is particularly challenging considering the ample comorbid chronic pain conditions and sensory disturbances entailed by the disease. The aim was to identify sensory features unique to CNP beyond those of chronic pain and MS.

Methods

Participants were 112 MS patients: 44 with a diagnosis of CNP, 28 with a diagnosis of chronic musculoskeletal pain (MSP), and 40 pain free. Participants underwent testing of thermal and mechanical thresholds, thermal grill illusion (TGI), pain adaptation (PA), and offset analgesia (OA), and chronic pain was characterized. A two‐step cluster analysis was performed, and the association between the cluster membership and the clinical group membership (CNP, MSP, pain free) was evaluated.

Results

The CNP and MSP groups were similar in most of the chronic pain variables (e.g., severity, location and quality) and MS‐related variables (e.g., type, severity and medication intake). The three created clusters had unique sensory features: (1) ‘Hyposensitivity’ (increased thermal and touch thresholds) characterized the CNP group; (2) ‘Poor inhibition and hyperalgesia’ (worst PA and OA and decreased TGI threshold) characterized the MSP group; and (3) ‘Efficient inhibition’ (best PA and OA, smallest sensory loss) characterized the pain‐free group.

Conclusions

The unique sensory features of CNP and MSP provide insight into their pathophysiology, and evaluating them may increase the ability to provide individually based interventions. Efficient inhibition may protect MS patients from chronic pain.

Significance

Cluster analysis among patients with multiple sclerosis (MS) revealed that while central neuropathic pain is associated with thermal and mechanical hypoesthesia, musculoskeletal pain is involved with reduced pain inhibition and hyperalgesia; sensory profiles that provide insights into the mechanisms of these conditions and may promote an individually based pain management.

Effectiveness of Dry Needling versus Placebo on Gait Performance, Spasticity, Electromyographic Activity, Pain, Range-of-Movement and Quality of Life in Patients with Multiple Sclerosis: A Randomized Controlled Trial Protocol

Dry needling (DN) is an emerging technique commonly used in neurological and musculoskeletal pain conditions, but there have been no previous studies in patients with multiple sclerosis (pwMS). This trial aims to assess the efficacy of deep DN, compared with sham placebo DN, on gait performance, spasticity level, pain, electromyographic activity, range-of-movement (ROM) and quality of life in pwMS. Forty adults with MS were randomly assigned to one study group. The DN group will undergo 2 sessions (once per week) using DN over the rectus femoris (RF) and gastrocnemius medialis (GM) muscles at the lower extremity with higher spasticity. The placebo group will receive the same protocol using a sham placebo needle (Dong Bang needle). Outcome measures will include gait performance, using the GaitRite^® system, spasticity level with the Modified Ashworth Scale, superficial electromyographic activity of RF and GM, pain (pressure algometer), ROM (goniometer), and quality of life (Musiqol). This study is the first investigating the short-term effect of DN, compared with placebo, in pwMS, and taking into account the possible changes in the electromyographic activity of the lower limb. Therefore, the results may help to understand the suitability of using this technique in the clinical setting for this population. Trial registration: ACTRN12619000880145.

Sensory and pain modulation profiles of ongoing central neuropathic extremity pain in multiple sclerosis

BACKGROUND

Central neuropathic extremity pain (CNEP) is the most frequent type of pain in multiple sclerosis (MS). The aim of the present study was to evaluate sensory and pain modulation profiles in MS patients with CNEP.

METHODS

In a single-centre observational study, a group of 56 CNEP MS patients was compared with 63 pain-free MS patients and with a sex- and age-adjusted control group. Standardized quantitative sensory testing (QST) and dynamic QST (dQST) protocols comprising temporal summation and conditioned pain modulation tests were used to compare sensory profiles.

RESULTS

Loss-type QST abnormalities in both thermal and mechanical QST modalities prevailed in both MS subgroups and correlated significantly with higher degree of disability expressed as Expanded Disability Status Scale (EDSS). Comparison of sensory phenotypes disclosed a higher frequency of the 'sensory loss' prototypic sensory phenotype in the CNEP subgroup (30%) compared with pain-free MS patients (6%; p = .003).

CONCLUSION

The role of aging process and higher lesion load in the spinothalamocortical pathway might be possible explanation for pain development in this particular 'deafferentation' subtype of central neuropathic pain in MS. We were unable to support the role of central sensitization or endogenous facilitatory and inhibitory mechanisms in the development of CNEP in MS.

SIGNIFICANCE

This article presents higher prevalence of the 'sensory loss' prototypic sensory phenotype in multiple sclerosis patients with central extremity neuropathic pain compared to pain-free patients. Higher degree of disability underlines the possible role of higher lesion load in the somatosensory pathways in this particular 'deafferentation' type of central neuropathic pain.

Chronic mechanical hypersensitivity in experimental autoimmune encephalomyelitis is regulated by disease severity and neuroinflammation

Chronic pain severely affects quality of life in more than half of people living with multiple sclerosis (MS). A commonly-used model of MS, experimental autoimmune encephalomyelitis (EAE), typically presents with hindlimb paralysis, neuroinflammation and neurodegeneration. However, this paralysis may hinder the use of pain behavior tests, with no apparent hypersensitivity observed post-peak disease. We sought to adapt the classic actively-induced EAE model to optimize its pain phenotype. EAE was induced with MOG_35-55/CFA and 100-600 ng pertussis toxin (PTX), and mice were assessed for mechanical, cold and thermal sensitivity over a 28-day period. Spinal cord tissue was collected at 14 and 28 days post-injection to assess demyelination and neuroinflammation. Only mice treated with 100 ng PTX exhibited mechanical hypersensitivity. Hallmarks of disease pathology, including demyelination, immune cell recruitment, cytokine expression, glial activation, and neuronal damage were higher in EAE mice induced with moderate (200 ng) doses of pertussis toxin, compared to those treated with low (100 ng) levels. Immunostaining demonstrated activated astrocytes and myeloid/microglial cells in both EAE groups. These results indicate that a lower severity of EAE disease may allow for the study of pain behaviors while still presenting with disease pathology. By using this modified model, researchers may better study the mechanisms underlying pain.

Widespread Pressure Pain Hyperalgesia Is Not Related to Pain in Patients with Parkinson's Disease

OBJECTIVE

Pain is one of the most frequent nonmotor impairments in Parkinson's disease (PD) and is hypothesized to be associated with altered nociceptive pain processing. Our aims were to investigate differences in widespread pressure pain sensitivity between PD patients with and without pain and healthy controls and to assess the relationship of health-related quality of life and sleep quality with pressure pain sensitivity.

METHODS

Nineteen PD patients with pain (12 men, age = 68 ± 9 years), 19 PD patients without pain (11 men, age = 69 ± 8 years), and 19 matched controls participated. Pressure pain thresholds (PPTs) were assessed bilaterally over the cervical spine, the second metacarpal, and the tibialis anterior by an assessor blinded to the subject's condition. Patients were assessed in a dopamine-medicated (ON) state. Pain intensity (numerical pain rating scale, 0-10), health-related quality of life (39-item Parkinson's Disease Questionnaire), and sleep quality (Pittsburgh Sleep Quality Index) were also assessed.

RESULTS

No significant differences existed between PD patients, with or without pain, and healthy controls on PPTs over the cervical spine, the second metacarpal, or the tibialis anterior muscle (all P > 0.3). PPTs were lower in females than in males in all groups (P < 0.01). In PD patients with pain, worse quality of sleep was associated with higher widespread pressure pain sensitivity (-0.607 < r < -0.535, P < 0.05). No other significant association was observed.

CONCLUSIONS

This study revealed no differences in widespread pressure hyperalgesia between PD patients with or without pain (ON state) and controls. Although dopamine may modulate pain responses, other mechanisms seems to also be implicated in altered nociceptive pain processing in patients with PD.

Peripheral neuropathy in patients with multiple sclerosis

OBJECTIVES

To determine the prevalence and severity of neuropathic pain, sudomotor dysfunction and abnormal vibration perception in patients with MS.

METHODS

73 patients with MS and 32 age-matched healthy controls underwent assessment of expanded disability severity score (EDSS), DN4 to assess neuropathic pain, electrochemical skin conductance (ESC) to assess sudomotor function and vibration perception threshold (VPT).

RESULTS

Patients with MS had a higher DN4 score (p < 0.001) with 14% fulfilling the criteria for neuropathic pain elevated VPT (p < 0.001) and lower ESC on the feet (p < 0.001) and hands (p < 0.001) compared to control participants. ESC on the feet (32% of MS patients) and hands (30% of MS patients) were lower, and DN4 (77% of MS patients) and VPT (64% of MS patients) were greater than 2SD of the healthy control values, respectively. EDSS correlated with the number of relapses (r = 0.564, p < 0.001), VPT (r = -0.457, < 0.001) and ESC on the feet (r = -0.268, p = 0.023).

CONCLUSIONS

Patients with multiple sclerosis have evidence of sudomotor dysfunction and elevated vibration perception, which were associated with neurological disability from MS.

Chronic pain in multiple sclerosis: A 10-year longitudinal study

BACKGROUND AND PURPOSE

Pain is a common symptom associated with multiple sclerosis (MS), and has lasting effects on an individual's functional capacity and quality of life. A wide range of prevalence rates of pain (between 23% and 90%)have been reported in MS and this is mainly due to the methodological differences amongst the studies such as variability in patient sources, method of sampling and the definition of pain used. Chronic pain in MS, defined as pain lasting for greater than 3-6 months, can have a significant impact on their biopsychosocial health, including negative impact on activities of daily living, relationships and social participation. The long-term course of MS-related pain and its impact in an Australian cohort over a 7-year period has been investigated earlier. The aim of this longitudinal study was to describe the impact of chronic pain, pain-related disability and carer burden in persons with MS over a 10-year period. The aim of this longitudinal study was to describe the impact of chronic pain, pain-related disability and carer burden in persons with MS over a 10-year period.

METHODS

This was a prospective longitudinal study conducted at the Rehabilitation Department of Royal Melbourne Hospital (RMH), a tertiary referral hospital in Victoria and Australia. The source of participants was from the RMH MS database and contains detailed MS patient information including demographic data, diagnosis details (using McDonald's criteria), pain characteristics. Structured face-face interviews and validated measures were used, which include the visual analogue scale (VAS); chronic pain grade (CPG); the assessment of quality of life (AQoL) and the carer strain index (CSI). The mean age of the participants (n=70) was 55.3 years and majority (70%) were female.

RESULTS

The mean age of the participants (n=70) was 55.3 years and majority (70%) were female. The findings show that over time (10 years), participants report having greater bilateral bodily pain and greater description of pain as 'worse as it could be'. Pain types were similar to 7-years follow-up but remained higher than baseline. There was a significant deterioration in quality of life in those with more severe CPG over time. Almost half of the participants 31 (44%) required care either from a private carer, institution or from a family member. Although fear of taking medications and side effects were common barriers to treatment for pain, there was an increase in the use of pharmacological treatment over time and an increase in the use of healthcare services, mainly neurologists and general practitioners.

CONCLUSIONS

The pain measures reported by the participants were similar to those at the 7-year follow-up except there was a greater representation of bilateral pain locations (limb, trunk and facial pain) compared to baseline and 7-year follow-up. At 10-year follow-up, more participants used medications compared to 7-year follow-up and there was an increase in the use of health professionals at the 10-year follow-up. At the 10-year follow up QoL of the participants deteriorated significantly and more participants had progressed to higher CPG III and CPG IV. This study demonstrates that chronic pain is a significant issue over time in MS, with clinical and health implications, impact on quality of life, disability and healthcare utilization.

IMPLICATIONS

Greater awareness of chronic pain in pwMS, cognitive classifications and an interdisciplinary approach is required to improve long-term patient outcomes and well-being.

Evidence of altered pressure pain thresholds in persons with disorders of consciousness as measured by the Nociception Coma Scale-Italian version

Pain assessment in patients with disorders of consciousness (DoC) is a controversial issue for clinicians, who require tools and standardised procedures for testing nociception in non-communicative patients. The aims of the present study were, first, to analyse the psychometric properties of the Italian version of the Nociception Coma Scale and, second, to evaluate pressure pain thresholds in a group of patients with DoC. The authors conducted a multi-centre study on 40 healthy participants and 60 DoC patients enrolled from six hospitals in Italy. For each group an electronic algometer was used to apply all nociceptive pressure stimuli. Our results show that the Italian version of the NCS retains the good psychometric properties of the original version and is therefore suitable for standardised pain assessment in clinical practice. In our study, pressure pain thresholds measured in a group of patients in vegetative and minimally conscious state were relatively lower than pain threshold values found in a group of healthy participants. Such findings motivate additional investigation on possible pain sensitisation in patients with severe brain injury and multiple co-morbidities, and on application of tailored therapeutic approaches useful for pain management in patients unable verbally to communicate their feelings.

Psychological Considerations in the Assessment and Treatment of Pain in Neurorehabilitation and Psychological Factors Predictive of Therapeutic Response: Evidence and Recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation

Background: In order to provide effective care to patients suffering from chronic pain secondary to neurological diseases, health professionals must appraise the role of the psychosocial factors in the genesis and maintenance of this condition whilst considering how emotions and cognitions influence the course of treatment. Furthermore, it is important not only to recognize the psychological reactions to pain that are common to the various conditions, but also to evaluate how these syndromes differ with regards to the psychological factors that may be involved. As an extensive evaluation of these factors is still lacking, the Italian Consensus Conference on Pain in Neurorehabilitation (ICCPN) aimed to collate the evidence available across these topics.

Objectives: To determine the psychological factors which are associated with or predictive of pain secondary to neurological conditions and to assess the influence of these aspects on the outcome of neurorehabilitation.

Methods: Two reviews were performed. In the first, a PUBMED search of the studies assessing the association between psychological factors and pain or the predictive value of these aspects with respect to chronic pain was conducted. The included papers were then rated with regards to their methodological quality and recommendations were made accordingly. In the second study, the same methodology was used to collect the available evidence on the predictive role of psychological factors on the therapeutic response to pain treatments in the setting of neurorehabilitation.

Results: The first literature search identified 1170 results and the final database included 189 articles. Factors such as depression, anxiety, pain catastrophizing, coping strategies, and cognitive functions were found to be associated with pain across the various conditions. However, there are differences between chronic musculoskeletal pain, migraine, neuropathy, and conditions associated with complex disability with regards to the psychological aspects that are involved. The second PUBMED search yielded 252 studies, which were all evaluated. Anxiety, depression, pain catastrophizing, coping strategies, and pain beliefs were found to be associated to different degrees with the outcomes of multidisciplinary programs, surgery, physical therapies, and psychological interventions. Finally, sense of presence was found to be related to the effectiveness of virtual reality as a distraction tool.

Conclusions: Several psychological factors are associated with pain secondary to neurological conditions and should be acknowledged and addressed in order to effectively treat this condition. These factors also predict the therapeutic response to the neurorehabilitative interventions.

Chronic Pain in Multiple Sclerosis Patients: Utility of Sensory Quantitative Testing in Patients with Fibromyalgia Comorbidity

BACKGROUND

Lower thermal and discomfort thresholds may predispose multiple sclerosis (MS) patients to chronic pain, but a possible effect of fibromyalgia (FM) comorbidity has never been investigated. Aims were to investigate the thermal and discomfort thresholds in the evaluation of pain intensity between MS patients with FM (PFM+) and MS patients with pain not associated to FM (PFM-).

METHODS

One hundred thirty three MS patients were investigated for chronic pain. FM was assessed according to the 1990 ACR diagnostic criteria. An algometer was used to measure the thresholds in the patients and 60 matched healthy subjects.

RESULTS

Chronic pain was present in 88 (66.2%) patients; 12 (13.6%) had neuropathic pain, 22 (17.3%) were PFM+ and 65 (48.9%) PFM-. PFM+ were predominantly female (p = 0.03) and had a greater EDSS (p = 0.01) than NoP; no other significant differences emerged than PFM-. The thresholds were lower in MS patients than controls (p < 0.01), mainly in the PFM+. FM severity influenced the thermal threshold (p < 0.001), while the female gender influenced the discomfort threshold (p < 0.001).

CONCLUSION

Thermal and discomfort thresholds were lower in patients than controls and were the lowest in PFM+. Their more severely impaired thermal threshold supports a neurophysiological basis of such association.