Physiopathology of symptoms and signs in multiple sclerosis

Pharmacological and Non-pharmacological Approaches for the Management of Neuropathic Pain in Multiple Sclerosis

Multiple sclerosis is a chronic inflammatory disease that affects the central nervous system and can cause various types of pain including ongoing extremity pain, Lhermitte's phenomenon, trigeminal neuralgia, and mixed pain. Neuropathic pain is a major concern for individuals with multiple sclerosis as it is directly linked to myelin damage in the central nervous system and the management of neuropathic pain in multiple sclerosis is challenging as the options available have limited efficacy and can cause unpleasant side effects. The literature search was conducted across two databases, PubMed, and Google Scholar. Eligible studies included clinical trials, observational studies, meta-analyses, systematic reviews, and narrative reviews. The objective of this article is to provide an overview of literature on pharmacological and non-pharmacological strategies employed in the management of neuropathic pain in multiple sclerosis. Pharmacological options include cannabinoids, muscle relaxants (tizanidine, baclofen, dantrolene), anticonvulsants (benzodiazepines, gabapentin, phenytoin, carbamazepine, lamotrigine), antidepressants (duloxetine, venlafaxine, tricyclic antidepressants), opioids (naltrexone), and botulinum toxin variants, which have evidence from various clinical trials. Non-pharmacological approaches for trigeminal neuralgia may include neurosurgical methods. Non-invasive methods, physical therapy, and psychotherapy (cognitive behavioral therapy, acceptance and commitment therapy and mindfulness-based stress reduction) may be recommended for patients with neuropathic pain in multiple sclerosis. The choice of treatment depends on the severity and type of pain as well as other factors, such as patient preferences and comorbidities. There is a pressing need for healthcare professionals and researchers to prioritize the development of better strategies for managing multiple sclerosis-induced neuropathic pain.

Fatigue, pain interference, and psychiatric morbidity in multiple sclerosis: The role of childhood stress

BACKGROUND

Multiple sclerosis (MS) is a progressive, autoimmune disease of the central nervous system that affects nearly one million Americans. Despite the existence of immunomodulatory therapies to slow physical and cognitive disability progression, interventions to ameliorate common symptoms of MS, including fatigue and pain, remain limited. Poor understanding of risk factors for these symptoms may contribute to treatment challenges. In recent years, childhood stress has been investigated as a risk factor for chronic autoimmune conditions including MS; yet remarkably few studies have investigated the relationship between childhood stressors and chronic MS symptoms. Our aim was to examine clusters of stressors and three key features of MS: fatigue, pain interference, and psychiatric morbidity.

METHODS

Cross-sectional data were collected from a sample of People with MS (PwMS) via a national web-based survey that assessed the presence and type of childhood stressors and MS clinical features. Hierarchical block regression was used to assess associations among emotional, physical, and environmental childhood stressors and three clinical features commonly experienced by PwMS.

RESULTS

N = 719 adults with MS (aged 21-85) completed the survey. Childhood emotional and physical stressors were significantly associated with overall presence of fatigue (p = 0.02; p<0.03) and pain interference (p<0.001; p<0.001) in adulthood, as well as the magnitude of both outcomes. Environmental stressors (p<0.001), in addition to emotional (p<0.001) and physical (p<0.001) stressors were significantly associated with psychiatric morbidity in PwMS.

CONCLUSION

Childhood stress may predict fatigue, psychiatric morbidity, and pain in adults with MS. Further research is needed to show cause and effect; however, if an association exists, strategies to mitigate the impact of childhood stress could offer new pathways to reduce the severity of these symptoms. Broadly, this work adds to the body of evidence supporting upstream preventive measures to help address the stress on children and families.

A systematic review of the symptomatic management of Lhermitte's phenomenon

INTRODUCTION

Lhermitte's phenomenon (LP) is a transient shock-like sensation that radiates down the spine into the extremities, usually with neck flexion. The potential efficacy and tolerability of various symptomatic therapies in the management of LP have not been systematically reviewed previously.

METHOD

A systematic review was conducted using PubMed, EMBASE, and the Cochrane Library from inception to August 2022 for peer-reviewed articles describing the treatment of patients with Lhermitte's phenomenon. The review adheres to the PRISMA guidelines and was registered on PROSPERO.

RESULTS

This systematic review included sixty-six articles, which included 450 patients with LP. Treatment of the underlying cause varied by aetiology. Whilst LP is most commonly considered in the context of structural pathology of the cervical cord, medication-induced LP was a common theme in the literature. The most common cause of medication-induced LP was platinum-based chemotherapy agents such as cisplatin and oxaliplatin. In medication-induced LP, symptoms typically resolved with cessation of the causative agent. Non-pharmacological treatment options were associated with mild-moderate symptomatic improvement. The most commonly used agents to treat patients with LP were carbamazepine and gabapentin, which resulted in variable degrees of symptomatic benefit.

CONCLUSIONS

No randomised studies currently exist to support the use of symptomatic therapies to treat LP. Observational data suggest that some therapies may yield a symptomatic benefit in the management of LP. However, this systematic review identified a significant paucity of evidence in the literature, which suggests that further controlled studies are needed to investigate the optimal management of this common neurologic phenomenon.

Novel therapeutic for multiple sclerosis protects white matter function in EAE mouse model

Multiple sclerosis (MS) is a chronic demyelinating disease with prominent axon dysfunction. Our previous studies in an MS mouse model, experimental autoimmune encephalomyelitis (EAE), demonstrated that major histocompatibility complex Class II constructs can reverse clinical signs of EAE. These constructs block binding and downstream signaling of macrophage migration inhibitory factors (MIF-1/2) through CD74, thereby inhibiting phosphorylation of extracellular signal-regulated kinase (ERK) activation and tissue inflammation and promoting remyelination. To directly assess the effects of a novel third generation construct, DRhQ, on axon integrity in EAE, we compared axon conduction properties using electrophysiology on corpus callosum slices and optic nerves. By using two distinct white matter (WM) tracts, we aimed to assess the impact of the EAE and the benefit of DRhQ on myelinated and unmyelinated axons as well as to test the clinical value of DRhQ on demyelinating lesions in CC and optic myelitis. Our study found that EAE altered axon excitability, delayed axon conduction and slowed spatiotemporal summation correlated with diffuse astrocyte and microglia activation. Because MS predisposes patients to stroke, we also investigated and showed that vulnerability to WM ischemia is increased in the EAE MS mouse model. Treatment with DRhQ after the onset of EAE drastically inhibited microglial and astrocyte activation, improved functional integrity of the myelinated axons and enhanced recovery after ischemia. These results demonstrate that DRhQ administered after the onset of EAE promotes WM integrity and function, and reduces subsequent vulnerability to ischemic injury, suggesting important therapeutic potential for treatment of progressive MS.

Consensus for the Early Identification of Secondary Progressive Multiple Sclerosis in Portugal: a Delphi Panel

INTRODUCTION

Multiple sclerosis is a disease with a heterogeneous evolution. The early identification of secondary progressive multiple sclerosis is a clinical challenge, which would benefit from the definition of biomarkers and diagnostic tools applicable in the transition phase from relapsing-remitting multiple sclerosis to secondary progressive multiple sclerosis. We aimed to reach a Portuguese national consensus on the monitoring of patients with multiple sclerosis and on the more relevant clinical variables for the early identification of its progression.

MATERIAL AND METHODS

A Delphi panel which included eleven Portuguese Neurologists participated in two rounds of questions between July and August of 2021. In the first round, 39 questions which belonged to the functional, cognitive, imaging, biomarkers and additional evaluations were included. Questions for which no consensus was obtained in the first round (less than 80% of agreement), were appraised by the panel during the second round.

RESULTS

The response rate was 100% in both rounds and consensus was reached for a total of 33 questions (84.6%). Consensus was reached for monitoring time, evaluation scales and clinical variables such as the degree of brain atrophy and mobility reduction, changes suggestive of secondary progressive multiple sclerosis. Additionally, digital devices were considered tools with potential to identify disease progression. Most questions for which no consensus was obtained referred to the cognitive assessment and the remaining referred to both functional and imaging domains.

CONCLUSION

Consensus was obtained for the determination of the monitorization interval and for most of the clinical variables. Most questions that did not reach consensus were related with the confirmation of progression taking into account only one test/domain, reinforcing the multifactorial nature of multiple sclerosis.

Medical Cannabis Activity Against Inflammation: Active Compounds and Modes of Action

Inflammation often develops from acute, chronic, or auto-inflammatory disorders that can lead to compromised organ function. Cannabis (Cannabis sativa) has been used to treat inflammation for millennia, but its use in modern medicine is hampered by a lack of scientific knowledge. Previous studies report that cannabis extracts and inflorescence inhibit inflammatory responses in vitro and in pre-clinical and clinical trials. The endocannabinoid system (ECS) is a modulator of immune system activity, and dysregulation of this system is involved in various chronic inflammations. This system includes cannabinoid receptor types 1 and 2 (CB1 and CB2), arachidonic acid-derived endocannabinoids, and enzymes involved in endocannabinoid metabolism. Cannabis produces a large number of phytocannabinoids and numerous other biomolecules such as terpenes and flavonoids. In multiple experimental models, both in vitro and in vivo, several phytocannabinoids, including Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabigerol (CBG), exhibit activity against inflammation. These phytocannabinoids may bind to ECS and/or other receptors and ameliorate various inflammatory-related diseases by activating several signaling pathways. Synergy between phytocannabinoids, as well as between phytocannabinoids and terpenes, has been demonstrated. Cannabis activity can be improved by selecting the most active plant ingredients (API) while eliminating parts of the whole extract. Moreover, in the future cannabis components might be combined with pharmaceutical drugs to reduce inflammation.

[Neuropathic pain syndromes in patients with multiple sclerosis]

Among the numerous pain syndromes (PS) of various localizations and types, observed in patients with multiple sclerosis (MS), the greatest attention of researchers is attracted by neuropathic PS. Neuropathic PS are often present already in the early stage of MS, significantly reduce the quality of life, hinder the social adaptation of patients, poorly respond to therapy. Central neuropathic PS, which pathogenesis is closely related with plaques in the central nervous system, are most common in patients with MS. Diagnostics of neuropathic PS in MS is based mainly on typical clinical symptoms; MRI and neurophysiological methods data are of secondary importance. This review focuses on modern concepts of three main neuropathic PS in MS: ongoing extremity pain, trigeminal neuralgia and Lhermitte's sign. Clinical symptoms of neuropathic PS, current ideas about their pathogenetic mechanisms, MRI and neurophysiological techniques data and the existing approaches to conservative therapy and surgical treatment based on randomized trials data are presented.

Are electrophysiological and oligodendrocyte alterations an element in the development of multiple sclerosis at the same time as or before the immune response?

Efficient communication between the glial cells and neurons is a bi-directional process that is essential for conserving normal functioning in the central nervous system (CNS). Neurons dynamically regulate other brain cells in the healthy brain, yet little is known about the first pathways involving oligodendrocytes and neurons. Oligodendrocytes are the myelin-forming cells in the CNS that are needed for the propagation of action potentials along axons and additionally serve to support neurons by neurotrophic factors (NFTs). In demyelinating diseases, like multiple sclerosis (MS), oligodendrocytes are thought to be the victims. Axonal damage begins early and remains silent for years, and neurological disability develops when a threshold of axonal loss is reached, and the compensatory mechanisms are depleted. Three hypotheses have been proposed to explain axonal damage: 1) the damage is caused by an inflammatory process; 2) there is an excessive accumulation of intra-axonal calcium levels; and, 3) demyelinated axons evolve to a degenerative process resulting from the lack of trophic support provided by myelin or myelin-forming cells. Although MS was traditionally considered to be a white matter disease, the demyelination process also occurs in the cerebral cortex. Recent data supports the notion that initial response is triggered by CNS injury. Thus, the understanding of the role of neuron-glial neurophysiology would help provide us with further explanations. We should take in account the suggestion that MS is in part an autoimmune disease that involves genetic and environmental factors, and the pathological response leads to demyelination, axonal loss and inflammatory infiltrates.

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.

Wilhelm Uhthoff and Uhthoff's phenomenon

Wilhelm Uhthoff, known for his contributions to both neurology and neuro-ophthalmology, was a German ophthalmologist who specialized in neurologic disorders. The eponym "Uhthoff's phenomenon" was first used to describe the reversible, transient blurring of vision in patients with multiple sclerosis during exercise. Subsequently, it was discovered that this neurologic sign not only was triggered by physical exertion but also by other homeostatic disruptions such as hot baths, menstruation, and high external temperatures. Here, we take a look at the life and career of Wilhelm Uhthoff and discuss the basis behind this phenomenon.

Characterization of the first symptoms of multiple sclerosis in a Brazilian center: cross-sectional study

CONTEXT AND OBJECTIVE:

Multiple sclerosis (MS) is a chronic, immune-mediated and degenerative central nervous system (CNS) disease with well-established diagnostic criteria. Treatment can modify the course of the disease. The objective of this study was to describe the initial symptoms of multiple sclerosis in a Brazilian medical center.

DESIGN AND SETTING:

Descriptive study, conducted in a Brazilian reference center for multiple sclerosis treatment.

METHODS:

Data on 299 patients with confirmed diagnoses of MS were included in the study. Their medical files were evaluated and the data were analyzed.

RESULTS:

The most common symptom involved the cranial nerves (50.83%) and unifocal manifestation was presented by the majority of this population (73.91%). The mean time between the first symptom and the diagnosis was 2.84 years. Unifocal symptoms correlated with longer time taken to establish the diagnosis, with an average of 3.20 years, while for multifocal symptoms the average time taken for the diagnosis was 1.85 years. Unifocal onset was related to greater diagnostic difficulty.

CONCLUSIONS:

MS is a heterogeneous disease and its initial clinical manifestation is very variable.

Prior regular exercise improves clinical outcome and reduces demyelination and axonal injury in experimental autoimmune encephalomyelitis

Although previous studies have shown that forced exercise modulates inflammation and is therapeutic acutely for experimental autoimmune encephalomyelitis (EAE), the long-term benefits have not been evaluated. In this study, we investigated the effects of preconditioning exercise on the clinical and pathological progression of EAE. Female C57BL/6 mice were randomly assigned to either an exercised (Ex) or unexercised (UEx) group and all of them were induced for EAE. Mice in the Ex group had an attenuated clinical score relative to UEx mice throughout the study. At 42 dpi, flow cytometry analysis showed a significant reduction in B cells, CD4(+) T cells, and CD8(+) T cells infiltrating into the spinal cord in the Ex group compared to UEx. Ex mice also had a significant reduction in myelin damage with a corresponding increase in proteolipid protein expression. Finally, Ex mice had a significant reduction in axonal damage. Collectively, our study demonstrates for the first time that a prolonged and forced preconditioning protocol of exercise improves clinical outcome and attenuates pathological hallmarks of EAE at chronic disease. In this study, we show that a program of 6 weeks of preconditioning exercise promoted a significant reduction of cells infiltrating into the spinal cord, a significant reduction in myelin damage and a significant reduction in axonal damage in experimental autoimmune encephalomyelitis (EAE) mice at 42 dpi. Collectively, our study demonstrates for the first time that a preconditioning protocol of exercise improves clinical outcome and attenuates pathological hallmarks of EAE at chronic disease.

Osteoporosis and multiple sclerosis: risk factors, pathophysiology, and therapeutic interventions

Multiple sclerosis (MS) is a chronic inflammatory-demyelinating disease of the nervous system. There has been mounting evidence showing that MS is associated with increased risk of osteoporosis and fractures. The development of osteoporosis in MS patients can be related to the cumulative effects of various factors. This review summarizes the common risk factors and physiologic pathways that play a role in development of osteoporosis in MS patients. Physical inactivity and reduced mechanical load on the bones (offsetting gravity) is likely the major contributing factor for osteoporosis in MS. Additional possible factors leading to reduced bone mass are low vitamin D levels, and use of medications such as glucocorticoids and anticonvulsants. The role of the inflammatory processes related to the underlying disease is considered in the context of the complex bone metabolism. The known effect of different MS disease-modifying therapies on bone health is limited. An algorithm for diagnosis and management of osteoporosis in MS is proposed.

Specific aspects of modern life for people with multiple sclerosis: considerations for the practitioner

Multiple sclerosis (MS) is a chronic, debilitating, neurodegenerative disease that has a high impact on patients' quality of life. Individuals are often diagnosed in early adulthood and are faced with the difficulty of managing their lifestyle within the context of this chronic illness. Here we review factors that influence the disease course and the challenges that might be encountered when managing patients with MS. The majority of diagnosed patients are women of childbearing age, making pregnancy-related issues a key concern. MS typically stabilizes during pregnancy and evidence suggests that the disease has no impact on the risk of complications or outcomes. However, the effect of disease-modifying therapies on outcomes is less clear, and discontinuation of treatment prior to pregnancy or when breastfeeding is recommended. Awareness of genetic risk factors is important for patients planning a family, as several genes increase the risk of MS. Further aspects that require consideration include infections, vaccinations, environmental factors, surgery and the emergence of osteoporosis. Vaccinations are generally not a risk factor for MS and may be beneficial in terms of protection against infection and reducing the number of relapses. Environmental factors such as vitamin D deficiency, low exposure to sunlight, smoking and Epstein-Barr virus infection can all negatively influence the disease course. Furthermore, osteoporosis is generally higher in patients with MS than the general population, and the risk is increased by the environmental and genetic factors associated with the disease; bone mineral density should be assessed and smoking cessation and correction of serum vitamin D levels are recommended. Finally, as patients with MS are typically young, they are at low risk of surgery-related complications, although they should be carefully monitored postoperatively. Awareness of, and planning around, these factors may minimize the impact of the disease on patients' lifestyle.

Neuroimaging biomarkers of neurodegenerative diseases and dementia

Neurodegenerative disorders leading to dementia are common diseases that affect many older and some young adults. Neuroimaging methods are important tools for assessing and monitoring pathological brain changes associated with progressive neurodegenerative conditions. In this review, the authors describe key findings from neuroimaging studies (magnetic resonance imaging and radionucleotide imaging) in neurodegenerative disorders, including Alzheimer's disease (AD) and prodromal stages, familial and atypical AD syndromes, frontotemporal dementia, amyotrophic lateral sclerosis with and without dementia, Parkinson's disease with and without dementia, dementia with Lewy bodies, Huntington's disease, multiple sclerosis, HIV-associated neurocognitive disorder, and prion protein associated diseases (i.e., Creutzfeldt-Jakob disease). The authors focus on neuroimaging findings of in vivo pathology in these disorders, as well as the potential for neuroimaging to provide useful information for differential diagnosis of neurodegenerative disorders.

Multiple sclerosis and mitochondrial gene variations: a review

Multiple sclerosis (MS) is a debilitating disease of the central nervous system. Its etiology is still an unanswered enigma; its symptoms are varied and unpredictable; and there is no cure for it. Genetics has been introduced as a contributing factor to MS. Not only may MS stem from nuclear gene variations/mutations, but also it may arise from mitochondrial gene variations/mutations. The association of mitochondrial DNA variations/mutations with the pathogenesis of MS has, so far, been analyzed by several studies. This paper reviews the literature with regard to MS and corresponding mitochondrial DNA variations.

Use of Fourier-domain OCT to detect retinal nerve fiber layer degeneration in Parkinson's disease patients

PURPOSE

To demonstrate axonal loss in the retinal nerve fiber layer (RNFL) of patients with Parkinson's disease (PD) and to evaluate the ability of Fourier-domain optical coherence tomography (OCT) to detect RNFL degeneration and retinal thinning in these patients.

METHODS

PD patients (n=100) and healthy subjects (n=100) were included in the study and underwent visual acuity, color vision, and OCT examinations using two next-generation Fourier-domain devices (Spectralis and Cirrus). Differences in the RNFL thicknesses were compared between patients and controls.

RESULTS

RNFL thicknesses were significantly reduced in PD patients compared with healthy subjects, especially those obtained using the Spectralis OCT, in the inferotemporal quadrant (155.6±16.5 μm in healthy eyes vs 142.1±24.9 μm in patients, P=0.040) and in the superotemporal quadrant (142.6±20.9 μm in healthy eyes vs 132.77±18.6 μm in PD patients, P=0.046). Significant differences were observed between controls and patients in relation to mean macular thickness (P=0.031), foveal thickness (P=0.030), and inferior outer thickness (P=0.019).

CONCLUSION

PD is associated with RNFL loss and retinal thinning, which is detectable by Fourier-domain OCT measurements.