Central and peripheral fatigue: exemplified by multiple sclerosis and myasthenia gravis

A systematic literature review of the measurement of patient-reported fatigue in studies of disease modifying therapies for multiple sclerosis

BACKGROUND

Fatigue is the most commonly experienced symptom among people with multiple sclerosis (MS) and has the greatest impact in reducing quality of life. It is important to measure change in MS-related fatigue (MS-fatigue) in response to treatment, particularly the more recent disease modifying therapies (DMTs). To date there has been no systematic literature review of the patient reported outcome (PRO) tools used to measure MS- fatigue specifically in the context of DMTs.

METHODS

MEDLINE, Embase and Clinicaltrials.gov were searched from 01 January 2000 to 13 April 2021 to identify published studies of the treatment of MS with DMTs. Studies where MS-fatigue was measured as an outcome using a PRO tool were included in the review. Further literature searches were undertaken to provide information about the development and validation of each PRO tool.

RESULTS

739 abstracts and 96 clinical trials were manually screened resulting in 68 articles for full text screening. 48 studies were identified for the review; 10 of these were RCTs that considered MS-fatigue as a secondary outcome (4 were Phase 3 trials). The PRO instruments used in the 10 RCTs were the Fatigue Scale for Motor and Cognitive Functions, Fatigue Impact Scale, Modified Fatigue Impact Scale, Fatigue Severity Scale, and Fatigue Symptoms and Impacts Questionnaire - Relapsing Multiple Sclerosis. The other 38 studies were all open-label, longitudinal, non-randomized studies and used the following PRO instruments in addition to those listed above: the Visual Analogue Scale for Fatigue, the Fatigue Descriptive Scale, Modified Fatigue Impact Scale (5 items) and the Würzburger Fatigue Inventory for MS. All these PRO tools were specifically developed for MS-fatigue. Of these 9 PRO tools, 7 were of good methodological quality according to the existing validation studies using the Consensus-based standards for the selection of health measurement instruments (COSMIN) check list and were used in the majority of the MS DMT studies (44/48, 92%). The median follow-up time from baseline to PRO measurement was 12 months (range 1-36 months). Most studies reported on MS fatigue in terms of its change from baseline and whether the change was statistically significant. 5 studies also reported what they considered to be a clinically meaningful difference.

CONCLUSIONS

Although fatigue has the greatest impact on quality of life in people with MS, few studies have rigorously investigated the impact of DMTs on fatigue. Comparisons between study outcomes using different PRO tools is challenging due to the variety of psychometric constructs addressed by the questionnaires and differences in the recall period for fatigue symptoms and the measurement scale. Furthermore most of the PRO tools used to quantify MS-fatigue in studies of DMTs are descended from PRO tools developed during the 1990s before DMTs emerged and before widespread patient involvement in PRO development. New PRO tools should involve patients in their development as recommended by the US Food and Drug Administration and the validation process should consider the sensitivity of the PRO tool to change in fatigue over time or between groups.

Effectiveness of Exercise Interventions on Body Composition, Exercise Capacity, Fatigue, and Quality of Life in Patients with Liver Cirrhosis: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Diminished muscle protein synthesis in cirrhosis leads to reduced strength and mass, impacting daily activities and overall quality of life.

AIMS

This study aimed to examine the effectiveness of exercise intervention in body composition, exercise capacity, fatigue, and quality of life in patients with liver cirrhosis.

METHODS

A systematic search of medical databases, including PubMed, Embase, Cochrane, and CINAHL, was executed from their inception to November 2022. The inclusion criteria were randomized controlled trials comparing exercise interventions with a control group that did not receive exercise interventions.

RESULTS

From the initially identified 2,565 articles, eight studies with a total of 220 patients were eligible for inclusion in this meta-analysis. According to the meta-analysis, exercise significantly improved the six-minute walk distance (6MWD) by 68.93 m (95% CI 14.29-123.57) compared to the control group. Furthermore, the subgroup analysis revealed that combing exercise with amino acid supplementation had a greater positive effect on the 6MWD (MD = 144.72, 95% CI 87.44-202.01). Exercise also significantly increased thigh circumference (MD = 1.26, 95% CI 0.12-2.39) and the thigh ultrasound average compression index (MD = 0.07, 95% CI 0.00-0.14). Moreover, exercise significantly decreased fatigue levels by 0.7 points in patients with liver cirrhosis (95% CI 0.38-1.03). However, no significant effects were observed on body mass index (BMI), fat mass, fat-free mass, and quality of life.

CONCLUSIONS

Exercise can improve exercise capacity, thigh muscle thickness, and fatigue in patients with cirrhosis, but it does not have a significant impact on fat mass, BMI, or quality of life.

Cognitive and mental fatigue in chronic pain: cognitive functions, emotional aspects, biomarkers and neuronal correlates-protocol for a descriptive cross-sectional study

INTRODUCTION

Chronic pain (CP) is one of the most frequently presenting conditions in health care and many patients with CP report mental fatigue and a decline in cognitive functioning. However, the underlying mechanisms are still unknown.

METHODS AND ANALYSIS

This study protocol describes a cross-sectional study aimed at investigating the presence of self-rated mental fatigue, objectively measured cognitive fatigability and executive functions and their relation to other cognitive functions, inflammatory biomarkers and brain connectivity in patients with CP. We will control for pain-related factors such as pain intensity and secondary factors such as sleep disturbances and psychological well-being. Two hundred patients 18-50 years with CP will be recruited for a neuropsychological investigation at two outpatient study centres in Sweden. The patients are compared with 36 healthy controls. Of these, 36 patients and 36 controls will undergo blood sampling for inflammatory markers, and of these, 24 female patients and 22 female controls, between 18 and 45 years, will undergo an functional MRI investigation. Primary outcomes are cognitive fatigability, executive inhibition, imaging and inflammatory markers. Secondary outcomes include self-rated fatigue, verbal fluency and working memory. The study provides an approach to study fatigue and cognitive functions in CP with objective measurements and may demonstrate new models of fatigue and cognition in CP.

ETHICS AND DISSEMINATION

The study has been approved by the Swedish Ethics Review Board (Dnr 2018/424-31; 2018/1235-32; 2018/2395-32; 2019-66148; 2022-02838-02). All patients gave written informed consent to participate in the study. The study findings will be disseminated through publications in journals within the fields of pain, neuropsychology and rehabilitation. Results will be spread at relevant national and international conferences, meetings and expert forums. The results will be shared with user organisations and their members as well as relevant policymakers.

TRIAL REGISTRATION NUMBER

NCT05452915.

Characterization of Muscle Weakness Due to Myasthenia Gravis Using Shear Wave Elastography

Myasthenia gravis (MG) is often accompanied with muscle weakness; however, little is known about mechanical adaptions of the affected muscles. As the latter can be assessed using ultrasound shear wave elastography (SWE), this study characterizes the biceps brachii muscle of 11 patients with MG and compares them with that of 14 healthy volunteers. Simultaneous SWE, elbow torque and surface electromyography measurements were performed during rest, maximal voluntary contraction (MVC) and submaximal isometric contractions (up to 25%, 50% and 75% MVC) at different elbow angles from flexion to extension. We found that, with increasing elbow angle, maximum elbow torque decreased (p < 0.001), whereas muscle stiffness increased during rest (p = 0.001), MVC (p = 0.004) and submaximal contractions (p < 0.001). Muscle stiffness increased with increasing contraction intensities during submaximal contractions (p < 0.001). In comparison to the healthy cohort, muscle stiffness of MG patients was 2.1 times higher at rest (p < 0.001) but 8.93% lower in active state (75% MVC, p = 0.044). We conclude that (i) increased muscle stiffness shown by SWE during rest might be an indicator of MG, (ii) SWE reflects muscle weakness and (iii) SWE can be used to characterize MG muscle.

Reduced quality of life in myasthenia gravis patients: A study on 185 patients from China

Aims

To explore the quality of life (QOL) in patients with myasthenia gravis (MG) and factors associated with QOL.

Methods

This observational study included patients with MG diagnosed at the First Affiliated Hospital of Fujian Medical University between January 2020 and March 2022. The QOL of patients was evaluated with the 15-item Myasthenia Gravis Quality of Life (MG-QOL15). Current MG severity was evaluated with MGFA grade, MG-ADL score, MGC score, and MGFA Postintervention Status. The data about gender, age of onset, subgroup, antibodies, age, duration, education, employment state, marital status, skeletal muscle affected, thymic histology, and current treatment methods of the patient were collected.

Results

A total of 185 patients [72 males (38.9%), aged 45.2 years (14-77)] with MG were enrolled. Age at onset was 38.3 ± 17.9 years, and disease duration was 87.9 months (0-672). The median MG-QOL15 score was 12.5 (0-58). The item "have trouble using my eyes" was the highest scoring item in both ocular and generalized patients with MG. The MG-QOL15 score was significantly different among patients with OMG (9.2 ± 9.4, n = 63), GMG (9.0 ± 8.8, n = 22), and BMG (15.4 ± 14.2, n = 100) (P = 0.018). Patients with BMG had higher MG-QOL15 scores than OMG (P = 0.001) and GMG (P = 0.009), but there was no significant difference between OMG and GMG (P = 0.467). The MG-QOL15 score was significantly lower in patients who had undergone thymectomy (9.7 ± 9.8, n = 58) compared to those who had not (13.8 ± 13.4, n = 127, P = 0.022). MG-QOL15 score was significantly lower in patients who underwent thymectomy compared to those who did not (9.7 ± 9.8, n = 58 vs. 13.8 ± 13.4, n = 127, P = 0.022). MG-QOL15 score was different among MGFA grades (Remission: 5.2 ± 5.4, n = 41; I: 11.3 ± 10, n = 61; II: 11.6 ± 11.1, n = 40; III: 18.1 ± 12.1, n = 29; and IVa: 30.1 ± 20, n = 14, P < 0.001). There was no significant difference between patients in MGFA grade I and II (P = 0.896), and there was no significant difference between patients in MGFA grade III and IVa (P = 0.052). MG-ADL (P < 0.001) and MGC (P < 0.001) were positively correlated with MG-QOL15. Men had higher MG-QOL15 than women (P = 0.094), and LOMG had higher MG-QOL15 than EOMG (P = 0.072). Multivariate linear regression identified that higher MG-ADL (P < 0.001), higher MGC (P = 0.02), and poor employment status (P = 0.045) were independently associated with higher MG-QOL15.

Conclusion

Having trouble using the eyes accounted for the highest score in MG-QOL15, eye symptoms affect QOL more than limb weakness in MG. Daily life activity, disease severity, and employment status were associated with patients' QOL. Adequate treatment should be applied to improve QOL, while mild symptoms can be accepted. Men and patients over the age of 50 years of onset may need more attention.

Cross-syndrome: myasthenia gravis and the demyelinating diseases of the central nervous system combination. Systematic literature review and case reports

Nowadays the problem of comorbidity is still relevant. In this review, we describe clinical cases of the disease of the neuromuscular junction (myasthenia gravis (MG) generalized form) and the demyelinating disease of the central nervous system (DD CNS) (multiple sclerosis, neuromyelitis optica spectrum disorder (NMOSD), etc.) combinations registered in our practice with precise pathogenetic analysis. Although the number of the described associations is growing every year, the exact development mechanisms of this cross syndrome as well as the nature of the association between the discussed autoimmune diseases remain unknown. At the beginning of both disorders there is a considerable loss of auto tolerance of the immune system and, as a result, an increased response from autoreactive T-lymphocytes to the structures of the nervous system: brain cells and neuromuscular synapses. There are three main theories for comorbidity: initial predisposition, direct case relationship with disease-modifying therapy (DMT) application, and coincidence. It is known that early diagnostics of MG and timely administration of necessary adequate treatment reduce the risk of process generalization and lead to a decline in mortality. Therefore, the offer to examine MS patients with atypical symptoms for possible MG identification seems very rational. Similarly, MG patients having uncharacteristic symptoms that can be indicative of other autoimmune nervous system diseases also demand special diagnostics. Considering the presence of similar pathogenetic links, several authors propose a possibility of a new nosological unit establishment, including described comorbidity.

Multiple sclerosis-related fatigue lacks a unified definition: A narrative review

Fatigue is the most common symptom in multiple sclerosis (MS). Although MS-related fatigue (MS-F) strongly affects quality of life and social performance of patients, there is currently a lack of knowledge about its pathophysiology, which in turns leads to poor objective diagnosis and management. Recent studies have attempted to explain potential etiologies as well as treatments for MS-F. However, it seems that without a consensus on its nature, these data could not provide a route to a successful approach. In this Article, we review definitions, epidemiology, risk factors and correlated comorbidities, pathophysiology, assessment methods, neuroimaging findings, and pharmacological and nonpharmacological treatments of MS-F. Further studies are warranted to define fatigue in MS patients more accurately, which could result in precise diagnosis and management.

Upper Extremity Motor Fatigability as an Early Indicator in Pediatric Onset Multiple Sclerosis

AIM

To adopt a computer-based protocol to assess grip fatigability in patients with pediatric-onset multiple sclerosis to provide detection of subtle motor involvement identifying those patients most at risk for future decline.

METHOD

Pediatric-onset multiple sclerosis patients were recruited during routine outpatient visits to complete a grip assessment and compared to a group of healthy age- and sex-matched controls. All participants completed a computer-based measurement of standard maximal grip strength and repetitive and sustained grip performance measured by dynamic and static fatigue indices.

RESULTS

A total of 38 patients with pediatric-onset multiple sclerosis and 24 healthy controls completed the grip protocol (right-hand dominant). There were no significant group differences in maximal grip strength bilaterally (right: 21.8 vs 19.9 kg, P = .25; left: 20.4 vs 18.7 kg, P = .33), although males with pediatric-onset multiple sclerosis were significantly less strong than healthy controls (right: 26.53 vs 21.23 kg, P = .009; left; 25.13 vs 19.63 kg, P = .003). Both dynamic and static fatigue indices were significantly higher bilaterally in pediatric-onset multiple sclerosis compared with healthy control participants (left-hand dynamic fatigue index: 18.6% vs 26.7%, P = .003; right-hand static fatigue index: 28.3% vs 41.3%, P < .001; left-hand static fatigue index: 31.9% vs 42.6%, P < .001).

CONCLUSION

Brief repeatable grip assessment including measures of dynamic and sustained static output can be a sensitive indicator of upper extremity motor involvement in pediatric-onset multiple sclerosis, potentially identifying those in need of intervention to prevent future disability.

Does Intensive Training of Attention Influence Cognitive Fatigability in Patients With Acquired Brain Injury?

Research Objectives

Impairments in attention and the speed of information processing are central to the experience of cognitive fatigue in patients with acquired brain injury (ABI). Attention may be improved through intensive training in a rehabilitation setting. The aim of the study was to investigate the feasibility of reducing cognitive fatigability (CF) using attention training and to explore the effect of two different approaches to attention training.

Design

Randomised controlled study in a rehabilitation setting.

Participants

59 patients (age 19-59 years) with mild to moderate stroke or traumatic brain injury in the early (<4 month) phase.

Interventions

Patients were randomly assigned to intensive specific training with Attention Process Training (APT) or Activity-Based Attention Training (ABAT) for 3-5 days per week for a period of 5-6 weeks with a total of 20 h, in addition to traditional interdisciplinary rehabilitation.

Main Outcome Measure

CF was conceptualised as performance decline in terms of an increased number of incorrect responses between the first and the last quintiles of the Paced Auditory Serial Addition Test (PASAT). A negative result was defined as fatigability. The evaluator of fatigability was blinded to treatment.

Results

At baseline, there were no differences between the groups in age, education, reasoning, anxiety or depression. After training, a significant treatment effect was found (p = 0.020), as the APT-group, but not the ABAT-group, had improved. However, after controlling for baseline differences regarding CF on the PASAT-f, the difference was no longer significant.

Conclusion

The results indicate that cognitive training might be a feasible method for reducing CF through attention training and that patients with high levels of CF benefit most from attention training. The type of intervention provided, whether specific or activity-based attention training, appears to be of less importance, as there was no treatment effect after controlling for the baseline level of CF. Future studies are required to confirm the validity of the findings.

Post-COVID-19 Fatigue: Potential Contributing Factors

Much of the spotlight for coronavirus disease 2019 (COVID-19) is on the acute symptoms and recovery. However, many recovered patients face persistent physical, cognitive, and psychological symptoms well past the acute phase. Of these symptoms, fatigue is one of the most persistent and debilitating. In this "perspective article," we define fatigue as the decrease in physical and/or mental performance that results from changes in central, psychological, and/or peripheral factors due to the COVID-19 disease and propose a model to explain potential factors contributing to post-COVID-19 fatigue. According to our model, fatigue is dependent on conditional and physiological factors. Conditional dependency comprises the task, environment, and physical and mental capacity of individuals, while physiological factors include central, psychological, and peripheral aspects. This model provides a framework for clinicians and researchers. However, future research is needed to validate our proposed model and elucidate all mechanisms of fatigue due to COVID-19.

The effect of tDCS on the fatigue in patients with multiple sclerosis: A systematic review of randomized controlled clinical trials

INTRODUCTION

Fatigue is one of the most common disabling symptoms in patients with multiple sclerosis (MS) which is present in 75% of these patients and is usually associated with functional disabilities. According to the literature, there is no general agreement on the effectiveness of the existing treatments for fatigue in patients with MS. As transcranial direct current stimulation (tDCS) is a relatively new method in the treatment of fatigue symptoms in patients with MS, the purpose of this study was to systematically review published evidence conducted to assess the effects of tDCS on fatigue in patients with MS.

MATERIAL & METHODS

A thorough literature search of published articles was conducted from 1996 to 2019 in different databases including PubMed, Science Direct, OVID, Google Scholar, Cochrane Library, Scopus, Embase, ProQuest and web of science with keywords of "tDCS", "multiple Sclerosis" and "Fatigue". Results yielded 1017 studies, which after excluding articles based on duplication and title and abstract, 8 of them were selected for review in this study.

RESULTS

The results from the literature revealed that six studies indicated positive effects of tDCS stimulation on fatigue reduction. In four studies stimulation was over the right dorsolateral prefrontal cortex (DLPFC); in three studies stimulation placed over the whole body's primary somatosensory cortex (S1); and in one study stimulation applied over the posterior parietal cortex. In most studies, no serious side effects were reported.

CONCLUSION

Most studies revealed that tDCS can reduce the adverse effects of MS-related fatigue in particular cognitive type. As follow-ups were either absent or short period, as well as the application of treatment protocols and measurement instruments were different, it was very difficult to draw strong conclusion on the effects of tDCS in patients with MS. However, further large scale studies with long term follow-up are still recommended.

Identifying the relevant determinants of MS related fatigue: The role of the clinical indicators of disease and personality

BACKGROUND AND OBJECTIVE

Research on the factors contributing to multiple sclerosis (MS) related fatigue are far from conclusive. Some studies put forward that clinical aspects of the disease give rise to this symptom whilst others emphasize the effects of psychological factors on its etiology. This study investigated the relationship between clinical aspects of MS and personality with MS fatigue.

METHOD

A total of 201 participants with MS of which 48 (23.9%) males and 153 (76.1%) females took part in this online study. Questionnaires were populated measuring clinical features of the disease (disease duration, type of MS, Expanded Disability Status Scale - EDSS), personality traits, and MS-related fatigue. Data was analyzed by hierarchical regression analyses.

RESULTS

Personality traits accounted for a greater variance in MS fatigue (R² = .482, p < .01) than clinical aspects of the disease, these results were conclusive after controlling for the sociodemographic variables and depression. Temperament explained in total 10.5% variance of fatigue and character an additional 4.0 %. High Harm avoidance (HA) (β = .229, p < .01) and low Self-directedness (SD) (β = -.217, p < .01) directly predicted fatigue. Also, temperament was shown to indirectly affect fatigue, through character. High HA and high Novelty-seeking (NS) through low SD predicted fatigue. The association between clinical features and fatigue was not observed unless paired with personality traits. EDSS in conjunction with HA and Secondary - progressive MS (SPMS) coupled with SD negatively affected fatigue levels.

CONCLUSION

Personality traits directly and indirectly predicted MS-related fatigue. Furthermore, the impact of clinical indicators of disease on fatigue would not be observed unless these features occurred together with particular personality traits.

Importance of fatigue and its measurement in chronic liver disease

The mechanisms of fatigue in the group of people with non-alcoholic fatty liver disease and non-alcoholic steatohepatitis are protean. The liver is central in the pathogenesis of fatigue because it uniquely regulates much of the storage, release and production of substrate for energy generation. It is exquisitely sensitive to the feedback controlling the uptake and release of these energy generation substrates. Metabolic contributors to fatigue, beginning with the uptake of substrate from the gut, the passage through the portal system to hepatic storage and release of energy to target organs (muscle and brain) are central to understanding fatigue in patients with chronic liver disease. Inflammation either causing or resulting from chronic liver disease contributes to fatigue, although inflammation has not been demonstrated to be causal. It is this unique combination of factors, the nexus of metabolic abnormality and the inflammatory burden of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis that creates pathways to different types of fatigue. Many use the terms central and peripheral fatigue. Central fatigue is characterized by a lack of self-motivation and can manifest both in physical and mental activities. Peripheral fatigue is classically manifested by neuromuscular dysfunction and muscle weakness. Therefore, the distinction is often seen as a difference between intention (central fatigue) versus ability (peripheral fatigue). New approaches to measuring fatigue include the use of objective measures as well as patient reported outcomes. These measures have improved the precision with which we are able to describe fatigue. The measures of fatigue severity and its impact on usual daily routines in this population have also been improved, and they are more generally accepted as reliable and sensitive. Several approaches to evaluating fatigue and developing endpoints for treatment have relied of biosignatures associated with fatigue. These have been used singly or in combination and include: physical performance measures, cognitive performance measures, mood/behavioral measures, brain imaging and serological measures. Treatment with non-pharmacological agents have been shown to be effective in symptom reduction, whereas pharmacological agents have not been shown effective.

Fatigue Due to Multiple Sclerosis: A Comparison Between Persian Medicine and Conventional Medicine

Fatigue is one of the most debilitating symptoms of multiple sclerosis (MS), and its definite pathophysiology is unclear. Studies have suggested some correlates for it including dysfunction or atrophy in different parts of the brain. This narrative review study compares the viewpoint of conventional medicine and Persian medicine (PM) about fatigue due to MS and introduces the treatments used for this complaint in PM with an evidence-based approach. PM scholars have used the term I’ya equal to fatigue and stated that I’ya might be due to exertion or not, while the latter (spontaneous I’ya) can be prodromal of a disease. This pathologic fatigue can be seen in a wide variety of neurologic diseases, though it is the most common in MS patients. Fatigue in MS can be considered one of the equivalents of spontaneous I’ya. According to PM texts, neurotonic herbs like Ferula, Citrus medica, Asarum europaeum, Ficus carica, and Juglans regia may be beneficial in alleviating fatigue by brain reinforcement. Different pharmacological mechanisms have been introduced for these plants including antioxidant and/or anti-inflammatory activities. The medicinal plants can be assumed as a valuable source for discovering new medicines for fatigue in MS. Designing preclinical and clinical studies evaluating the effects of mentioned medicinal herbs in fatigue is proposed for obtaining more conclusive results.

Regional neuronal activity in patients with relapsing remitting multiple sclerosis

OBJECTIVES

Although interferon-beta is an established drug for relapsing remitting multiple sclerosis (RRMS), its impact on neuronal activity is not well understood.

METHODS

We investigated 15 patients with RRMS by [¹⁸ F]fluorodeoxyglucose positron emission tomography (FDG-PET) to assess cerebral metabolic rate of glucose (CMR_glc ) before interferon-beta therapy. Further, we performed clinical and neuropsychological investigations. In nine patients, these investigations were repeated after 6 months of therapy. Ten healthy controls were also studied.

RESULTS

We found no significant differences in absolute CMR_glc between patients and controls, or in patients before and during treatment. However, during treatment, relative regional glucose metabolism (rCMRl_glc ) was decreased in cerebellum and increased in parts of left inferior parietal, temporo-occipital, frontal cortical areas, left striatum and right insula. In untreated patients, higher fatigue was associated with lower rCMRl_glc in portions of left posterior cingulate cortex, and higher depression was associated with lower rCMRl_glc within the left superior temporal sulcus. In the pooled sample, higher depression was associated with higher rCMRl_glc in parts of the right precuneus.

CONCLUSIONS

Our results indicate effects of IFN-beta treatment on cerebellar, cortical and subcortical neuronal function. Moreover, more severe fatigue and depression in untreated patients seem to be associated with reduced neuronal activity in left posterior cingulate cortex and left superior temporal cortex, respectively.

Hypothalamic Dysfunction and Multiple Sclerosis: Implications for Fatigue and Weight Dysregulation

Signs and symptoms of multiple sclerosis are usually attributed to demyelinating lesions in the spinal cord or cerebral cortex. The hypothalamus is a region that is often overlooked yet controls many important homeostatic functions, including those that are perturbed in multiple sclerosis. In this review we discuss how hypothalamic dysfunction may contribute to signs and symptoms in people with multiple sclerosis. While dysfunction of the hypothalamic-pituitary-adrenal axis is common in multiple sclerosis, the effects and mechanisms of this dysfunction are not well understood. We discuss three hypothalamic mechanisms of fatigue in multiple sclerosis: (1) general hypothalamic-pituitary-adrenal axis hyperactivity, (2) disordered orexin neurotransmission, (3) abnormal cortisol secretion. We then review potential mechanisms of weight dysregulation caused by hypothalamic dysfunction. Lastly, we propose future studies and therapeutics to better understand and treat hypothalamic dysfunction in multiple sclerosis. Hypothalamic dysfunction appears to be common in multiple sclerosis, yet current studies are underpowered and contradictory. Future studies should contain larger sample sizes and standardize hormone and neuropeptide measurements.

Potential pathophysiological pathways that can explain the positive effects of exercise on fatigue in multiple sclerosis: A scoping review

BACKGROUND

Fatigue is one of the most common and most disabling symptoms of multiple sclerosis (MS). It is a multidimensional and complex symptom with multifaceted origins, involving both central and peripheral fatigue mechanisms. Exercise has proven to be safe for people with MS, with cumulating evidence supporting significant reductions in fatigue. However, the potential pathophysiological pathways that can explain the positive effects of exercise on fatigue in MS remain elusive.

OBJECTIVES

The objectives were, in PwMS (1) to update the knowledge on the pathophysiology underlying primary and secondary fatigue, and (2) to discuss potential pathophysiological pathways that can explain the positive effects of exercise on MS fatigue.

METHODS

A comprehensive literature search of six databases (PubMed, Embase, Cochrane Library, PEDro, CINAHL and SPORTDiscus) was performed. To be included, the study had to 1) enroll participants with definite MS according to defined criteria, 2) assess explicit pathophysiological mechanisms related to MS fatigue, 3) be available in English, Danish or French, and 4) had undergone peer-review.

RESULTS

A total of 234 studies fulfilled the inclusion criteria. Primary MS fatigue mainly originated from a dysfunction of central nervous system neuronal circuits secondary to increased inflammation, reduced glucose metabolism, brain atrophy and diffuse demyelination and axonal lesions. Secondary MS fatigue was linked with sleep disturbances, depression, cognitive impairments, and deconditioning. Cardiovascular, immunologic, neuroendocrine, and neurotrophic changes associated with exercise may alleviate primary MS fatigue while exercise may improve secondary MS fatigue through symptomatic improvement of deconditioning, sleep disorders, and depression.

CONCLUSIONS

>30 primary and secondary pathophysiological fatigue pathways were identified underlining the multidimensionality and complexity of MS fatigue. Though the underlying key cellular and molecular cascades still have to be fully elucidated, exercise holds the potential to alleviate MS fatigue, through both primary and secondary fatigue pathways.

Impaired sleep-associated modulation of post-exercise corticomotor depression in multiple sclerosis

OBJECTIVE

To compare the beneficial effect of nap versus rest on the recovery of motor evoked potentials (MEPs) after a fatiguing exercise performed in patients with multiple sclerosis (MS) and healthy controls.

METHODS

In 12 MS patients and 12 healthy controls, MEPs were recorded from the adductor pollicis muscle before, 10 and 60 min (T0, T10, and T60) after an effort of thumb adduction at 25% of maximal voluntary contraction force for 24 min. After the effort, the subject was maintained at rest or invited to have a nap while monitored with polysomnography. The two sessions (nap and rest) were randomly performed in each subject during the same day. The impact of nap and rest on post-exercise changes in MEP amplitude were studied in each group (patients and controls) and then compared between the two groups.

RESULTS

Although MEP amplitude at baseline was lower in MS patients than in controls, post-exercise corticomotor depression (PECD), expressed as T10/T0 MEP amplitude ratio, was similar in both groups. Regarding MEP amplitude recovery at T60, nap was significantly more beneficial than rest in healthy subjects, but not in MS patients.

CONCLUSION

Motor recovery from PECD following a fatiguing exercise can be enhanced by sleep (at least a short nap) in healthy subjects. In MS patients, sleep restorative effect is reduced or lost, maybe contributing to the excessive fatigue or fatigability characterized in these patients.

Do cognitive and physical fatigue tasks enhance pain, cognitive fatigue, and physical fatigue in people with fibromyalgia?

OBJECTIVE

Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task, and a dual fatigue task.

METHODS

In total, 24 people with fibromyalgia and 33 healthy controls completed pain, fatigue, and function measures. A cognitive fatigue task (Controlled Oral Word Association Test) and physical fatigue task (Valpar peg test) were done individually and combined for a dual fatigue task. Resting pain, perceived cognitive fatigue, and perceived physical fatigue were assessed during each task using visual analog scales. Function was assessed with shoulder range of motion and grip.

RESULTS

People with fibromyalgia had significantly higher increases in pain, cognitive fatigue, and physical fatigue when compared to healthy controls after completion of a cognitive fatigue task, a physical fatigue task, or a dual fatigue task (P < 0.01) with the exception of perceived cognitive fatigue during the cognitive fatigue task. People with fibromyalgia performed equivalently on measures of physical performance and cognitive performance on the physical and cognitive fatigue tasks, respectively.

CONCLUSION

These data show that people with fibromyalgia show larger increases in pain, perceived cognitive fatigue, and perceived physical fatigue to both cognitive and physical fatigue tasks compared to healthy controls. The increases in pain and fatigue during cognitive and physical fatigue tasks could influence subject participation in daily activities and rehabilitation.

[Fatigue in patients following traumatic brain injury and stroke]

BACKGROUND

Fatigue may be defined as an experience of long-term or recurrent tiredness and reduced capacity for mental and/or physical activity, and is common following acquired brain injury. This article provides an overview of the status of knowledge on fatigue following stroke and traumatic brain injury.

MATERIAL AND METHOD

An assessment of the existing literature, including a literature search, as well as the authors' own clinical experience form the basis for the content of this article.

RESULTS

Existing studies use varying definitions of fatigue and apply different survey tools. The prevalence of fatigue following stroke or traumatic brain injury is uncertain due to varying inclusion criteria and survey methods, and because different times of measurement can result in different prevalence figures. Several studies estimate the prevalence to be between 50 and 70%. Our knowledge of the pathologic mechanisms is very limited; premorbid, sociodemographic, stroke/trauma-related and comorbid factors all play a role in the experience of fatigue. Therapeutic interventions include psychoeducation, regulation of activity, physical exercise and treatment of comorbid conditions. Trials have also been conducted on drug treatment, so far without convincing results.

INTERPRETATION

Fatigue occurs frequently in stroke patients and patients with traumatic brain injuries, and often significantly restricts daily functioning for these patients. Our knowledge of pathologic mechanisms and evidence with regard to therapeutic interventions is deficient, and the patient population is heterogeneous. The treatment is adapted to the individual and its objective is to enable individuals to use their limited capacity in the most appropriate way possible.

Speech-related fatigue and fatigability in Parkinson's disease

This study tested the assumption that speech is more susceptible to fatigue than normal in persons with dysarthria. After 1 h of speech-like exercises, participants with Parkinson's disease (PD) were expected to report increased perceptions of fatigue and demonstrate fatigability by producing less precise speech with corresponding acoustic changes compared to neurologically normal participants. Twelve adults with idiopathic PD and 13 neurologically normal adults produced sentences with multiple lingual targets before and after six 10-min blocks of fast syllable or word productions. Both groups reported increasing self-perceived fatigue over time, but trained listeners failed to detect systematic differences in articulatory precision or speech naturalness between sentences produced before and after speech-related exercises. Similarly, few systematic acoustic differences occurred. These findings do not support the hypothesis that dysarthric speakers are particularly susceptible to speech-related fatigue; instead, speech articulation generally appears to be resistant to fatigue induced by an hour of moderate functional exercises.

Fatigue and fatigability in neurologic illnesses: proposal for a unified taxonomy

Fatigue is commonly reported in many neurologic illnesses, including multiple sclerosis, Parkinson disease, myasthenia gravis, traumatic brain injury, and stroke. Fatigue contributes substantially to decrements in quality of life and disability in these illnesses. Despite the clear impact of fatigue as a disabling symptom, our understanding of fatigue pathophysiology is limited and current treatment options rarely lead to meaningful improvements in fatigue. Progress continues to be hampered by issues related to terminology and assessment. In this article, we propose a unified taxonomy and a novel assessment approach to addressing distinct aspects of fatigue and fatigability in clinical and research settings. This taxonomy is based on our current knowledge of the pathophysiology and phenomenology of fatigue and fatigability. Application of our approach indicates that the assessment and reporting of fatigue can be clarified and improved by utilizing this taxonomy and creating measures to address distinct aspects of fatigue and fatigability. We review the strengths and weaknesses of several common measures of fatigue and suggest, based on our model, that many research questions may be better addressed by using multiple measures. We also provide examples of how to apply and validate the taxonomy and suggest directions for future research.

IgM-mediated autoimmune responses directed against anchorage epitopes are greater in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) than in major depression

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and depression are considered to be neuro-immune disorders (Maes and Twisk, BMC Medicine 8:35, 2010). There is also evidence that depression and ME/CFS are accompanied by oxidative and nitrosative stress (O&NS) and by increased autoantibodies to a number of self-epitopes some of which have become immunogenic due to damage by O&NS. The aim of this study is to examine IgM-mediated autoimmune responses to different self-epitopes in ME/CFS versus depression. We examined serum IgM antibodies to three anchorage molecules (palmitic and myristic acid and S-farnesyl-L-cysteine); acetylcholine; and conjugated NO-modified adducts in 26 patients with major depression; 16 patients with ME/CFS, 15 with chronic fatigue; and 17 normal controls. Severity of fatigue and physio-somatic (F&S) symptoms was measured with the Fibromyalgia and Chronic Fatigue Syndrome Rating Scale. Serum IgM antibodies to the three anchorage molecules and NO-phenylalanine were significantly higher in ME/CFS than in depression. The autoimmune responses to oxidatively, but not nitrosatively, modified self-epitopes were significantly higher in ME/CFS than in depression and were associated with F&S symptoms. The autoimmune activity directed against conjugated acetylcholine did not differ significantly between ME/CFS and depression, but was greater in the patients than controls. Partially overlapping pathways, i.e. increased IgM antibodies to a multitude of neo-epitopes, underpin both ME/CFS and depression, while greater autoimmune responses directed against anchorage molecules and oxidatively modified neo-epitopes discriminate patients with ME/CFS from those with depression. These autoimmune responses directed against neoantigenic determinants may play a role in the dysregulation of key cellular functions in both disorders, e.g. intracellular signal transduction, cellular differentiation and apoptosis, but their impact may be more important in ME/CFS than in depression.

Poststroke fatigue is associated with caudate infarcts

OBJECTIVE

The caudate nucleus may be involved in the pathogenesis of the fatigue observed in neurological disorders. However, the significance of caudate lesions in poststroke fatigue (PSF) is unknown. This study examined the association between caudate infarcts and PSF.

METHODS

Five hundred Chinese patients with acute ischemic stroke admitted to the acute stroke unit of a university-affiliated regional hospital in Hong Kong participated in the study. All participants were assessed for PSF with the Fatigue Severity Scale (FSS) three months after their index stroke. PSF was defined as a mean FSS score of 4.0 or more. Physical functioning and depressive symptoms were measured by the Barthel Index (BI) and the Geriatric Depression Scale (GDS).

RESULTS

One hundred and twenty-five (25.0%) of the patients had PSF. Compared to the non-fatigue group, the PSF patients were more likely to be women and had hyperlipidemia, lower BI and higher GDS scores. Caudate (8.0% versus 1.3%, p=0.001) and putamen (19.2% versus 12.0%, p=0.043) acute infarcts were more common in the PSF group, whereas pons infarcts (13.6% versus 22.2%, p=0.038) were less common. Acute caudate infarcts remained an independent predictor of PSF in the multivariate analysis, with an odds ratio of 6.4.

CONCLUSIONS

The results suggest that patients with PSF are more likely to have caudate infarcts.

Fatigue in multiple sclerosis - a brief review

Fatigue is the most common and debilitating symptom in multiple sclerosis (MS) and is believed to be distinctly different from fatigue seen in other chronic conditions. It can affect a patient's mood, sleep and have a detrimental effect on their quality of life. In the recent years much literature has emerged in an attempt to elucidate the potential causes and treatment of this common symptom. This review article aims to examine the most recent theories on the pathophysiology of fatigue in MS as well as its association with sleep and depression. We describe the pharmacological and non-pharmacological approaches to its treatment and propose a multidisciplinary, patient enabled and individualised manner to the management of fatigue in MS.

Neurobiological studies of fatigue

Fatigue is a symptom associated with many disorders, is especially common in women and in older adults, and can have a huge negative influence on quality of life. Although most past research on fatigue uses human subjects instead of animal models, the use of appropriate animal models has recently begun to advance our understanding of the neurobiology of fatigue. In this review, results from animal models using immunological, developmental, or physical approaches to study fatigue are described and compared. Common across these animal models is that fatigue arises when a stimulus induces activation of microglia and/or increased cytokines and chemokines in the brain. Neurobiological studies implicate structures in the ascending arousal system, sleep executive control areas, and areas important in reward. In addition, the suprachiasmatic nucleus clearly plays an important role in homeostatic regulation of the neural network mediating fatigue. This nucleus responds to cytokines, shows decreased amplitude firing rate output in models of fatigue, and responds to exercise, one of our few treatments for fatigue. This is a young field but very important as the symptom of fatigue is common across many disorders and we do not have effective treatments.

Targeting fatigue in stroke patients

Symptoms of fatigue are often reported by patients in both the acute and chronic stages of recovery following a stroke. It is commonly associated with low mood and sleep disturbances, but can arise in their absence. However, it has also been associated with poorer long-term outcome and, as such, its aetiology warrants a greater understanding. There is convincing evidence that inflammatory cascades and cytokine signalling precipitated by the infarct promote fatigue, and these pathways may harbour therapeutic targets in its management.

Building a measure of fatigue: the functional assessment of Chronic Illness Therapy Fatigue Scale

The shared goal of all clinical disciplines is to optimize the well-being of people who become patients and find themselves diminished by illness and recovery. This goal relies on sound tools to evaluate both real and perceived deficits in a way that can be used for a particular patient over time and also across medical disciplines and patient populations. Fatigue is a critical and notoriously subjective aspect of many illnesses. Although the soundness of research is often correlated with the objectivity of data, certain clinical measures must, by definition, be patient centered, with all the complexities and challenges of patient-reported evaluations. Measurement of fatigue has been an important and evolving component of symptom management in the field of oncology. The Functional Assessment of Chronic Illness Therapy Fatigue Scale is a self-administered fatigue-assessment tool that has found wide application across diverse medical fields and that has demonstrated validity and utility across a broad range of populations. The Functional Assessment of Chronic Illness Therapy Fatigue Scale has become one in a repository of tools in the item banks that are accumulating under the auspices of The Patient-Reported Outcomes Measurement Information System, a National Institutes of Health initiative to deploy the most clinically relevant and technologically agile tools that we have to advance research in medicine and patient care. As much as with any other discipline, physical medicine and rehabilitation stands to gain from the collective knowledge and creative horizons in the assessment and treatment of fatigue.

What is fatigue? Pathological and nonpathological fatigue

Aid in understanding issues surrounding the construct validity of fatigue including the distinction between pathological versus nonpathological fatigue. Fatigue is a universal symptom reported by individuals in the general population as well as by those suffering from different medical and psychological illnesses, including cancer, multiple sclerosis, chronic fatigue syndrome, depression, and anxiety. Chronic fatigue is a significant problem in many primary care settings, and the debilitating and prolonged nature of fatigue can pose significant economic consequences for society. Researchers have struggled to better assess and understand the etiology and classification of fatigue within different illness groups.