Pain and Cognition in Multiple Sclerosis

Rest-Activity Rhythm, Pain, and Motor Activity in Multiple Sclerosis

BACKGROUND

Although the relationships among physical disability, mood disorders, and pain are well described in multiple sclerosis (MS), little is known about whether those symptoms are associated with sleep disturbances.

METHODS

Forty-six patients with MS experiencing pain participated. Sleep was indirectly measured by assessing rest-activity rhythm via actigraphy: interdaily stability, intradaily variability, and relative amplitude. Pain was assessed using visual and verbal analog scales, mood by the Beck Depression Inventory and Symptom Checklist-90, and physical disability by the Expanded Disability Status Scale.

RESULTS

Incorporating mood, pain, and physical disability into 1 regression model resulted in a significant association with interdaily stability.

CONCLUSIONS

Compared with intradaily variability and relative amplitude, interdaily stability seems to be the most vulnerable actigraphy variable for mood disturbances, pain, and physical disabilities.

Pain and cognitive performance in adults with multiple sclerosis: A systematic review

INTRODUCTION

Pain and cognitive dysfunction are separately known to be important manifestations of multiple sclerosis (MS). Although pain is a complex subjective phenomenon with affective and cognitive aspects, it is not known if people with MS reporting pain are at greater risk of reduced performance in objective tests of cognition. The presence or direction of any association remains to be clarified, as do the roles of confounders such as fatigue, medication and mood.

METHODS

We conducted a systematic review of studies examining the relationship between pain and objectively measured cognition in adults with confirmed MS, according to a pre-registered protocol (PROSPERO 42,020,171,469). We carried out searches in MEDLINE, Embase and PsychInfo. Studies of adults with any subtype of MS, with chronic pain and in which cognitive evaluation was conducted by validated instruments were included. We evaluated the role of potential confounders (medication, depression, anxiety, fatigue and sleep) and described findings by eight pre-specified cognitive domains. Risk of bias was assessed using the Newcastle-Ottawa Scale.

RESULTS

11 studies (n = 3714 participants, range 16 to 1890 per study) were included in the review. Four studies included longitudinal data. Nine studies identified a relationship between pain and objectively measured cognitive performance. In seven of these studies, higher pain scores were associated with poorer cognitive performance. However, no evidence was available for some cognitive domains. Heterogeneous study methodology precluded meta-analysis. Studies infrequently controlled for the specified confounders. Most studies were judged to be at risk of bias.

DISCUSSION

Several studies, but not all, identified a negative relationship between pain severity and objectively measured cognitive performance. Our ability to further characterise this relationship is limited by study design and lack of evidence in many cognitive domains. Future studies should better establish this relationship and delineate the neurological substrate underpinning it.

Coupling cognitive and brainstem dysfunction in multiple sclerosis-related chronic neuropathic limb pain

Chronic pain in multiple sclerosis is common and difficult to treat. Its mechanisms remain incompletely understood. Dysfunction of the descending pain modulatory system is known to contribute to human chronic pain conditions. However, it is not clear how alterations in executive function influence this network, despite healthy volunteer studies linking function of the descending pain modulatory system, to cognition. In adults with multiple sclerosis-associated chronic neuropathic limb pain, compared to those without pain, we hypothesized altered functional connectivity of the descending pain modulatory system, coupled to executive dysfunction. Specifically we hypothesized reduced mental flexibility, because of potential importance in stimulus reappraisal. To investigate these hypotheses, we conducted a case-control cross-sectional study of 47 adults with relapsing remitting multiple sclerosis (31 with chronic neuropathic limb pain, 16 without pain), employing clinical, neuropsychological, structural, and functional MRI measures. We measured brain lesions and atrophy affecting descending pain modulatory system structures. Both cognitive and affective dysfunctions were confirmed in the chronic neuropathic limb pain group, including reduced mental flexibility (Delis Kaplan Executive Function System card sorting tests P < 0.001). Functional connectivity of rostral anterior cingulate and ventrolateral periaqueductal gray, key structures of the descending pain modulatory system, was significantly lower in the group experiencing chronic neuropathic pain. There was no significant between-group difference in whole-brain grey matter or lesion volumes, nor lesion volume affecting white matter tracts between rostral anterior cingulate and periaqueductal gray. Brainstem-specific lesion volume was higher in the chronic neuropathic limb pain group (P = 0.0017). Differential functional connectivity remained after correction for brainstem-specific lesion volume. Gabapentinoid medications were more frequently used in the chronic pain group. We describe executive dysfunction in people with multiple sclerosis affected by chronic neuropathic pain, along with functional and structural MRI evidence compatible with dysfunction of the descending pain modulatory system. These findings extend understanding of close inter-relationships between cognition, function of the descending pain modulatory system, and chronic pain, both in multiple sclerosis and more generally in human chronic pain conditions. These findings could support application of pharmacological and cognitive interventions in chronic neuropathic pain associated with multiple sclerosis.

Pain, cognition and disability in advanced multiple sclerosis

OBJECTIVES

In patients with multiple sclerosis (MS), a relationship between physical disability and pain has been observed. In addition a relationship between physical disability and cognition in MS has been suggested. However, cognitive functions and pain appear not to be correlated in MS patients. Therefore, we examined whether a possible relationship between pain and cognitive functioning may exist, and if so, if such a relationship is mediated by physical disability.

METHODS

Forty-five MS patients with chronic pain, and in an advanced stage of the disease were included. Physical disabilities were assessed by the Expanded Disability Status Scale (EDSS). Episodic memory was assessed by means of the Eight Words test, and Face and Picture Recognition. Executive functions (EF) were examined by Digit Span Backward for working memory, and the Rule Shift Cards and Category Fluency test for cognitive flexibility. Pain Intensity and Pain Affect were assessed by means of visual analogue scales and one verbal pain scale and mood (depression, anxiety) by the Beck Depression Inventory and the Symptom Check List (SCL-90). The research questions were analyzed by means of regression analyses and the Sobel test for mediation.

RESULTS

A significant relationship was found between Pain Affect and EF, but that relationship was not mediated by physical disabilities (EDSS). In addition, Pain Intensity and EF showed a significant relationship but only in combination with physical disabilities (EDSS). Finally, mood was related to pain affect.

DISCUSSION

The findings suggest that the lower the EF, exclusively or in combination with more physical disabilities, the more the patient may suffer from pain.

IMPLICATIONS

The more one is cognitively and physically impaired, the more one might suffer from pain, and, the less one is able to communicate pain. The latter could put MS patients at risk for underdiagnosing and undertreatment of pain.

Subgroup Analysis of Individuals with Multiple Sclerosis Showing Cognitive Resilience

OBJECTIVE

Cognitive dysfunction is known to occur in many individuals with multiple sclerosis (MS). However, little is currently known about MS patients without cognitive impairment, including protective factors associated with intact cognition. The present study considered these issues in a sample of MS patients screened for intact subjective and objective cognitive functioning.

METHODS

Two MS participant groups from a larger sample were derived: i) participants within 1 standard deviation of controls on measures of objective cognition, subjective cognition, and informant-observed subjective cognition [cognitively resilient MS group (MScr)], and ii) those classified as not cognitively resilient (MSncr). Both groups were compared with age- and gender-matched controls.

RESULTS

Findings indicated that the MScr group was similar to the MSncr group on most disease and demographic variables, and level of fatigue. The MScr group showed higher estimated baseline intellectual ability and reported less anxiety, subclinical depressive symptoms, and pain interference. MScr participants also showed a trend toward more reported compensatory cognitive strategy use than MSncr participants. The MScr group showed comparable reading recognition and pain symptoms to controls.

CONCLUSIONS

Our findings provide preliminary information on factors associated with cognitive resilience in MS. Future research should examine resilient individuals with MS to further clarify positive outcomes in this condition.

Strain and sex differences in somatosensation and sociability during experimental autoimmune encephalomyelitis

Multiple Sclerosis (MS) is an immune-mediated disease that results in major locomotor deficits. However, recent studies have revealed that fatigue, slow processing speed, and memory impairment are the top variables impacting employment status for MS patients. These suggest that cognitive effects may have a greater impact on productivity, lifestyle, and quality of life than do disease-related motor deficits. However, these debilitating non-locomotive effects have been largely overlooked in rodent models of the disease, such as experimental autoimmune encephalomyelitis (EAE). We hypothesized that murine EAE can also be used to assess non-locomotive dysfunctions (mood, sociability, muscle strength, and balance), as well as potential biases in these dysfunctions due to sex and/or strain. We actively immunized male and female C57BL/6 (B6) and SJL mice for EAE and evaluated their performance on the Deacon's weight grip test, Kondziela's inverted screen test, Hall's rope grip test, manual von Frey test for somatic nociception, and a three-chamber social preference paradigm. We hypothesized that EAE progression is associated with changes in muscle strength, balance, pain, and sociability and that these variations are linked to sex and/or strain. Our results indicate that strain but not sex influenced differences in muscle strength and balance during EAE, and both sex and strain have an impact on mechanical nociception, regardless of EAE disease status. Furthermore, both sex and strain had complex effects on differences in sociability. In conclusion, testing these additional modalities during EAE helps to unveil other signs and symptoms that could be used to determine the efficacy of a drug or treatment in the modulation of a MS-like behavior.

Crotoxin down-modulates pro-inflammatory cells and alleviates pain on the MOG35-55-induced experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis

Multiple sclerosis (MS) is a Central Nervous System inflammatory demyelinating disease that has as primary symptoms losses of sensory and motor functions, including chronic pain. To date, however, few studies have investigated the mechanisms of chronic pain in animal models of MS since locomotor impairments render difficult its evaluation. It was previously demonstrated that in the MOG_35-55-induced EAE, an animal model of MS, the hypernociception appears before the onset of motor disability, allowing for the study of these two phenomena separately. Here, we evaluated the effect of crotoxin (CTX), a neurotoxin isolated from the Crotalus durissus terrificus snake venom that displays, at non-toxic dose, antinociceptive, anti-inflammatory and immunomodulatory effects, in the pain and in symptoms progression of EAE. The pain threshold of female C57BL/6 mice decreased at the 4th day after immunization, while the first sign of disease appeared around the 11st-12nd days, coinciding with the onset of motor abnormalities. CTX (40 µg/kg, s.c.) administered in a single dose on the 5th day after immunization, induced a long-lasting analgesic effect (5 days), without interfering with the clinical signs of the disease. On the other hand, when crotoxin was administered for 5 consecutive days, from 5th-9th day after immunization, it induced analgesia and also reduced EAE progression. The antinociceptive effect of crotoxin was blocked by Boc-2 (0.5 mg/kg, i.p.), a selective antagonist of formyl peptide receptors, by NDGA (30 μg/kg, i.p.), a lipoxygenase inhibitor and by atropine sulfate (10 mg/kg, i.p.), an antagonist of muscarinic receptors, administered 30 min before CTX. CTX was also effective in decreasing EAE clinical signs even when administered after its onset. Regarding the interactions between neurons and immunocompetent cells, CTX, in vitro, was able to reduce T cell proliferation, decreasing Th1 and Th17 and increasing Treg cell differentiation. Furthermore, in EAE model, the treatment with 5 consecutive doses of CTX inhibited IFN-γ-producing T cells, GM-CSF-producing T cells, reduced the frequency of activated microglia/macrophages within the CNS and decreased the number of migrating cell to spinal cord and cerebellum at the peak of the disease. These results suggest that CTX is a potential treatment not only for pain alteration but also for clinical progression induced by the disease as well as an useful tool for the development of new therapeutic approaches for the multiple sclerosis control.

Sensory Function and Chronic Pain in Multiple Sclerosis

Objective

To examine whether hypoesthesia and chronic pain are related in patients with MS.

Methods

Sixty-seven MS patients with pain and 80 persons without MS were included. Sensory functioning was tested by bedside neurological examination. Touch, joint position (dorsal column-medial lemniscus pathway), temperature sense, and pain (spinothalamic tract) were tested. Pain intensity was measured by the Colored Analogue Scale (CAS Intensity) and the Faces Pain Scale (FPS); pain affect was also measured by CAS Affect and Number of Words Chosen-Affective (NWC-A). Mood was assessed with the SCL-90 anxiety and depression subscales and the Beck Depression Inventory (BDI).

Results

A significant negative relationship was found between pain intensity and the function of the dorsal column-medial lemniscal pathway, but not with the spinothalamic tract.

Conclusion

In addition to the already known relation between hyperesthesia and pain, hypoesthesia for touch and joint position also seems to be related to chronic pain in MS patients.

Survivorship and Outcomes in Patients With Multiple Sclerosis Undergoing Total Joint Arthroplasty

BACKGROUND

Patients with multiple sclerosis (MS) frequently require total joint arthroplasty (TJA). The outcomes of TJA in patients with MS, who are frequently on immunomodulatory medications and physically deconditioned, remain largely unknown. The aim of this study is to elucidate the survivorship and reasons for failure in this patient population.

METHODS

A single-institution retrospective review of 108 TJAs (46 knees and 62 hips) was performed from 2000 to 2016. An electronic chart query based on MS medications and International Classification of Diseases, Ninth Revision codes was used to identify this population followed by a manual review to confirm the diagnosis. Outcomes were then assessed using revision for any reason as the primary end point. Functional outcomes were assessed using Short Form 12 scores. Survivorship curves were generated using the Kaplan-Meier method.

RESULTS

At an average follow-up of 6.2 years, 19.4% (21/108) of patients required a revision surgery. Instability (5.6%, P = .0278) and periprosthetic joint infection (4.6%, P = .0757) were among the most common reasons for revision. The overall survivorship of TJA at years 2, 5, and 7, respectively, was 96.5% (95% confidence interval [CI], 92.6-100), 86.3% (95% CI, 77.7-94.5), and 75.3% (95% CI, 63.5-87.0). Functional score improvement was less in MS cohort than patients without MS.

CONCLUSION

Patients with MS are at increased risk of complications, particularly instability and periprosthetic joint infection. Despite this increased risk of complications, patients with MS can demonstrate improved functional outcomes, but not as much as patients without MS. Patients with MS should be counseled appropriately before undergoing TJA.

Psychiatric and physical comorbidities and pain in patients with multiple sclerosis

Background

It has been observed that patients with multiple sclerosis (MS), who have psychiatric and physical comorbidities such as depression and COPD, have an increased risk of experiencing more pain. In this study, we have distinguished between pain intensity and pain affect, as the latter, particularly, requires treatment. Furthermore, while pain and comorbidities have been assessed using questionnaires, this is possibly a less reliable method for those who are cognitively vulnerable.

Objective

The aim of this study was to determine whether psychiatric and physical comorbidities can predict pain intensity and pain affect in MS patients, susceptible to cognitive impairment.

Methods

Ninety-four patients with MS and 80 control participants participated in this cross-sectional study. Besides depression and anxiety, 47 additional comorbidities were extracted from patients’ medical records. Depression and anxiety were assessed using the Beck Depression Inventory and the Symptom Check List-90. Pain was assessed using the Number of Words Chosen Affective, Coloured Analog Scale, and the Faces Pain Scale. Cognitive functions, for example, memory and executive functions, were assessed using several neuropsychological tests.

Results

The main findings indicate that psychiatric comorbidities (depression and anxiety) predict both pain intensity and pain affect and that total physical comorbidity predicts only pain affect in MS patients, susceptible to cognitive impairment.

Conclusion

Both psychiatric and physical comorbidities predict pain affect. All three clinical outcomes enhance MS patients’ suffering.