'Fatigue' in patients with multiple sclerosis. Motor pathway conduction and event-related potentials

Comparison of physical performance, gait, balance, falls efficacy, and step reaction time in individuals with multiple sclerosis

OBJECTIVE

The study aimed to investigate the physical performance, gait, balance, falls efficacy, and step reaction time in individuals with MS.

METHODS

A total of 60 individuals (30 individuals with MS and 30 age and sex-matched healthy controls) were enrolled. Individuals' physical performance was evaluated with the Timed Up and Go Test (TUG) and Five-Times-Sit-to-Stand Test (FTSTS). Activities-specific Balance Confidence (ABC) Scale, 12-item Multiple Sclerosis Walking Scale (MSWS-12v2) and Falls Efficacy Scale International (FES-I) were used to assess the balance, gait and fall efficacy of the participants. Individuals' step reaction time (SRT) was calculated with video-based software. The time between the step command and the first contact of the foot with the ground in the first step was recorded.

RESULTS

The mean age of the individuals with MS and the control group was 38.5 ± 9.4 years and 33.9 ± 11.7 years, respectively. Significant differences existed between the groups in SRT, FES-I, ABC, and FTSTS (p < 0.05). There was no significant correlation between SRT with any other parameter (p > 0.05). TUG was moderately correlated with MSWS-12 and FES-I (r1 =0.426, r2 =0.495, p < 0.05). Besides, there was a moderate correlation between ABC with TUG and FTSTS (r1 =-0.605, r2 =-0.468, p < 0.05). A high degree correlation was found between MSWS-12 with FES-I and ABC (r1 =0.843, r2 =-0.834, p < 0.05).

CONCLUSION

Individuals with MS have decreased SRTs. However, this condition was not found to be related to physical performance. Further studies should focus on the association of SRT with cognitive and psychosocial parameters.

The Neurobiology of Pathological Fatigue: New Models, New Questions

The last decade has seen the emergence of new theoretical frameworks to explain pathological fatigue, a much neglected, yet highly significant symptom across a wide range of diseases. While the new models of fatigue provide new hypotheses to test, they also raise a number of questions. The primary purpose of this essay is to examine the predictions of three recently proposed models of fatigue, the overlap and differences between them, and the evidence from diseases that may lend support to the models of fatigue. I also present expansions for the sensory attenuation model of fatigue. Further questions examined here are the following: What are the neural substrates of fatigue? How can sensory attenuation, which underpins agency also explain fatigue? Are fatigue and agency related?

The Potential Role of Neurophysiology in the Management of Multiple Sclerosis-Related Fatigue

Fatigue is a very common symptom among people with multiple sclerosis (MS), but its management in clinical practice is limited by the lack of clear evidence about the pathogenic mechanisms, objective tools for diagnosis, and effective pharmacological treatments. In this scenario, neurophysiology could play a decisive role, thanks to its ability to provide objective measures and to explore the peripheral and the central structures of the nervous system. We hereby review and discuss current evidence about the potential role of neurophysiology in the management of MS-related fatigue. In the first part, we describe the use of neurophysiological techniques for exploring the pathogenic mechanisms of fatigue. In the second part, we review the potential application of neurophysiology for monitoring the response to pharmacological therapies. Finally, we show data about the therapeutic implications of neurophysiological techniques based on non-invasive brain stimulation.

Transcranial Magnetic Stimulation as a Potential Biomarker in Multiple Sclerosis: A Systematic Review with Recommendations for Future Research

Multiple sclerosis (MS) is a demyelinating disorder of the central nervous system. Disease progression is variable and unpredictable, warranting the development of biomarkers of disease status. Transcranial magnetic stimulation (TMS) is a noninvasive method used to study the human motor system, which has shown potential in MS research. However, few reviews have summarized the use of TMS combined with clinical measures of MS and no work has comprehensively assessed study quality. This review explored the viability of TMS as a biomarker in studies of MS examining disease severity, cognitive impairment, motor impairment, or fatigue. Methodological quality and risk of bias were evaluated in studies meeting selection criteria. After screening 1603 records, 30 were included for review. All studies showed high risk of bias, attributed largely to issues surrounding sample size justification, experimenter blinding, and failure to account for key potential confounding variables. Central motor conduction time and motor-evoked potentials were the most commonly used TMS techniques and showed relationships with disease severity, motor impairment, and fatigue. Short-latency afferent inhibition was the only outcome related to cognitive impairment. Although there is insufficient evidence for TMS in clinical assessments of MS, this review serves as a template to inform future research.

Myogenic and Central Neurogenic Factors in Fatigue in Multiple Sclerosis

Short episodes of electrical stimulation were applied to the right quadriceps muscle of patients with multiple sclerosis (MS) and healthy subjects at different times during 60 sec sustained voluntary muscle contractions at 0 to 100% levels of maximal voluntarily generated joint torque. The amplitude of electrically induced increments of torque (ΔT) has been shown to depend upon both the level of muscular contraction and time from the beginning of the contraction. The dependence of ΔT upon the time from the beginning of contraction has been assumed to reflect muscle fatigue. Patients with MS demonstrated an apparent involvement of central neurogenic mechanisms in fatigue manifested as a drop in muscle torque during sustained contractions at 75 and 100% levels when electrical stimulation was able to induce considerable increments in muscle torque. These patients also demonstrated a dependence of ΔT upon the contraction level suggesting that they did not produce maximal voluntary contraction torque in the pre-trial. Fatigue in MS is due to central, neurogenic factors and does not seem to involve any myogenic factors such as might be related to secondary muscle changes due to the long-standing disorder. The subjective feeling of tiredness (‘fatigue’) may be related to a dissociation between central motor commands (‘effort’) and their mechanical consequences.

Fatigue in multiple sclerosis: multidimensional assessment and response to symptomatic treatment

Sixty relapsing-remitting multiple sclerosis (MS) patients were selected on the basis of their score on the Fatigue Severity Scale (FSS) and formed two groups: 40 patients (fatigued MS; MSf) scored above the 75th percentile of a previously assessed representative MS sample (100 patients), and 20 age- and sex-matched patients (nonfatigued MS patients; MSnf) scored below the 25th percentile. The patients underwent clinical evaluation (Expanded Disability Status Scale (EDSS)), further assessment of fatigue (Fatigue Impact Scale), scales evaluating depression (Hamilton Depression Rating Scale (HDRS) and Beck’s Depression Inventory (BDI)) and neuropsychological tests. All patients were evaluated for muscle fatigability and central activation by means of a biomechanical test of sustained contraction; they also underwent somatosensory evoked potentials (SSEPs) and transcranial magnetic stimulation (TMS). The patients of the MSf subgroup were then randomized to one of the following two treatments: 4-aminopyridine (4-AP) 24 mg/day and fluoxetine (FLX) 20 mg/day. After a one-week titration this treatment proceeded for 8 weeks. At the end of the treatment, EDSS, fatigue and depression scores were further evaluated. At baseline, fatigue test scores consistently correlated with depression and cognitive test scores, but not with the fatigability test. Fatigue scores decreased in both treatment groups in a similar way. Due to the design of the study, this cannot be disjoined from a placebo effect. The changes of fatigue scores could not be predicted in the FLX group, whereas in the 4-AP group higher basal fatigability test scores were associated with greater reduction in fatigue scores.

Event-related potentials and cognitive performance in multiple sclerosis patients with fatigue

The aim of this study was to evaluate event-related potentials (ERP) and cognition in multiple sclerosis (MS) patients with regard to fatigue and disease-related variables. The study comprised 86 MS patients and 40 controls. Fatigue was assessed using the Fatigue Severity Scale (FSS/FSS-5) and the Modified Fatigue Impact Scale (MFIS/MFISmod). N200 and P300 components of auditory ERP were analyzed. Cognition was evaluated by means of Brief Repeatable Battery of Neuropsychological Tests (BRBNT). The results of ERP and BRBNT were compared between non-fatigued, moderately and severely fatigued MS patients and controls. P300 latency was significantly longer in the whole MS group and in the fatigued patients than in the controls. A positive correlation was found between P300 latency and MFIS/MFISmod results, independent from age and MS-related variables. The fatigued patients scored less than non-fatigued ones in tests evaluating memory, visuomotor abilities and attention. Results of these tests correlated significantly with fatigue measures, independently from MS-related variables. Fatigue in MS patients showed significant relationships with impairment within the memory and attention domains. Parameters of auditory ERP, as electrophysiological biomarkers of cognitive performance, were not independently linked to fatigue.

Self-Care, Productivity and Leisure Limitations of People with Multiple Sclerosis in Manitoba

As part of the activities of the Social Action Committee of the Multiple Sclerosis Society (Manitoba Division), a large mail-out survey was conducted in the spring of 1995. The purpose of the survey was to gather demographic, health, social and financial information from members who have multiple sclerosis to support various government lobbying efforts and to plan individual and family services. The response rate for the 720 surveys sent was 65%. This paper presents descriptive analysis exploring the occupational performance limitations experienced by the survey respondents based on the Model of Occupational Performance (CAOT, 1991). The prevalence of limitation was found to vary by specific occupation, by type of multiple sclerosis, by area of occupational performance, but not by fatigue status. The study findings have assessment and intervention implications for occupational therapists who work with people with multiple sclerosis in both institutional and community settings.

The Impact of Fatigue on Patients with Multiple Sclerosis

Although fatigue is recognized as a symptom of MS, there have been insufficient methods for evaluating this symptom. We administered the Fatigue Impact Scale to 85 MS patients and 20 hypertensive patients. Neurologic impairment, mental health, and general health status were also assessed. MS patients reported significantly higher fatigue impact than hypertensive patients. Most MS patients reported fatigue as either their worst (14%), or one of their worst (55%) symptoms. Disease classification and neurologic impairment had little bearing on Fatigue Impact Scale scores in the MS sample. The best predictive models for mental health and general health status in the MS sample both included the Fatigue Impact Scale as a significant factor. This study demonstrates that: 1) fatigue is a very prevalent and severe problem in MS, 2) fatigue impact cannot be predicted by clinical measures of neurologic impairment, 3) fatigue has a significant effect on the mental health and general health status of MS patients.

Cognition and physical disability in predicting health-related quality of life in multiple sclerosis

Many studies have shown that multiple sclerosis (MS) has a significant impact on patient health-related quality of life (HRQOL), but the relative contributions of physical versus cognitive disability are not well established. Most studies have relied on HRQOL outcomes that depend largely on patient mood, life satisfaction, and personal happiness. The Sickness Impact Profile (SIP) is a measure of HRQOL known for its relatively strong emphasis on task completion and activities of daily living. As such, the SIP may be less influenced by depression. We sought to determine the relative influence of physical disability and cognition, above and beyond demographic and disease variables, in predicting HRQOL. Patients (n = 132) and healthy controls (n = 26) underwent complete neuropsychological evaluation using the Minimal Assessment of Cognitive Function in MS (MACFIMS) battery and a series of self-report measures assessing depression, fatigue, and HRQOL. The SIP was also administered. Correlation analysis and group comparisons revealed significant associations between cognition and HRQOL outcomes. Logistic regression models comparing the Expanded Disability Status Scale (EDSS) and cognitive tests in predicting poor physical HRQOL retained both EDSS and Symbol Digit Modalities Test (SDMT) performance, while models predicting poor psychosocial and poor overall HRQOL retained only the SDMT. These findings support cognition as a significant predictor of overall HRQOL, psychosocial HRQOL, and, interestingly, physical HRQOL.

Clinical neurophysiology of multiple sclerosis

The availability of new treatments able to modify the natural course of multiple sclerosis (MS) has generated interest in paraclinical measures to monitor disease evolution. Among these, neurophysiologic measures, mainly evoked potentials (EPs), are used in the functional assessment of central sensorimotor and cognitive networks affected by MS. EP abnormalities may reveal subclinical lesions, objectivate the involvement of sensory and motor pathways in the presence of vague disturbances, and provide indications of the demyelinating nature of the disease process. However, their diagnostic value is much lower than that of magnetic resonance imaging, and is more sensitive to brain and cervical spinal cord lesions. The application of EPs in assessing disease severity and monitoring the evolution of nervous damage is more promising, thanks to their good correlation with disability in cross-sectional and longitudinal studies, and potential use as paraclinical endpoints in clinical trials. Recent evidence indicates that EPs performed early in the disease may help to predict a worse future progression in the long term. If confirmed, these data suggest the possible usefulness of EPs in the early identification of patients who are more likely to develop future disability, thus requiring more frequent monitoring or being potential candidates for more aggressive disease-modifying treatments.

Abnormal cervical cord function contributes to fatigue in multiple sclerosis

Background/Objective

We aimed to investigate whether cervical cord damage and dysfunction is associated with the presence and severity of fatigue in multiple sclerosis (MS) using a multiparametric magnetic resonance (MR) approach.

Methods:

Cervical cord functional magnetic resonance imaging (fMRI) during a tactile stimulation of the right hand, and structural brain and cord MRI were acquired from 20 controls, 15 MS patients without fatigue (NF) and 20 MS patients with fatigue (F). Between-group differences in the extent of focal lesions and diffusivity abnormalities in the brain and cord, cord-normalized cross-sectional area (CSAn) and fMRI activity were assessed.

Results:

All structural MRI measures differed significantly among groups, except for cord lesion number and CSAn. Compared with controls, NF-MS patients experienced higher cord recruitment ( p=0.04). Compared with F-MS, NF-MS patients had a lower brain normal-appearing white matter average fractional anisotropy ( p=0.001) and increased cord recruitment ( p=0.02). In patients with MS, the extent of cord recruitment was correlated with the severity of fatigue ( r=-0.34, p=0.04). Compared with the other two groups, F-MS patients had a more diffuse recruitment of cord quadrants on the axial and longitudinal planes.

Conclusions:

Abnormalities of function, but not of structure, of the cervical cord are likely to contribute to the pathogenesis of fatigue in MS.

Management options in multiple sclerosis-associated fatigue

INTRODUCTION

Multiple sclerosis (MS) is a chronic, inflammatory, autoimmune disease of the CNS. Its characteristic early clinical course includes exacerbations and remissions of neurologic disability. Fatigue is one of the most common symptoms of MS and is associated with a reduced quality of life; it is described as the worst symptom of the disease by 50 - 60% of patients. Yet, due to limitations of available evidence, current therapeutic approaches for treating fatigue are based mainly on preliminary studies and expert consensus.

AREAS COVERED

This review summarizes current knowledge on the physiopathology, diagnosis and therapeutic options for MS-associated fatigue, including both pharmacological and non-pharmacological strategies.

EXPERT OPINION

Large, rigorously designed trials can provide more reliable results on the efficacy of interventions for fatigue, their functional impact on everyday activities and patient quality of life. Future research should also address a better understanding of the physiopathologic mechanisms of fatigue and the development and validation of objective assessment tools to be used together with patient self-ratings.

European neuroborreliosis: quality of life 30 months after treatment

OBJECTIVES

The prognosis after Lyme neuroborreliosis (LNB) is debated. The aim of this study was to assess health-related Quality of Life (QoL) and neurological symptoms 30 months after treatment in European patients with LNB.

MATERIALS AND METHODS

In a prospective case-control designed study, we investigated 50 well-characterized patients with LNB who had participated in a treatment trial for LNB 30 months earlier and 50 matched control persons with the health QoL questionnaire Short-Form 36 (SF-36), the Fatigue Severity Scale (FSS), the Montgomery and Åsberg Depression Rating Scale (MADRS), the Starkstein Apathy Scale (SAS), and the Mini Mental State (MMS). Clinical and demographic data were collected by semi-structured interviews and clinical neurological examination.

RESULTS

Lyme neuroborreliosis-treated patients scored lower than control persons in the SF-36 domains physical component summary (PCS) (44 vs 51 P < 0.001) and mental component summary (MCS) (49 vs 54 P = 0.010). They also scored lower than control persons in all the SF-36 subscales, except for bodily pain, and on FSS (3.5 vs 2.1 P < 0.001), but not on MMS (28 vs 29 P = 0.106). There was a difference in MADRS (3.1 vs 0. 8 P = 0.003) and SAS (13 vs 11 P = 0.016), but the scores were low in both groups. Fatigue was the most frequently reported symptom among LNB-treated patients (50%). Patients who reported complete recovery (56%) after LNB had similar QoL scores as the controls.

CONCLUSION

European persons treated for LNB have poorer health-related QoL and have more fatigue than persons without LNB.

The NEO-FFI in Multiple Sclerosis: internal consistency, factorial validity, and correspondence between self and informant reports

Personality assessment is a potentially important component of clinical and empirical work with neurological patients because (a) individual differences in personality may be associated with different neurological outcomes and (b) central nervous system changes may give rise to alteration in personality. For personality assessment to be useful to clinicians and researchers, the tests must be reliable and valid, as self-report measures require certain baseline levels of comprehension and insight, both of which can be compromised by cerebral disease. In this study, the authors examined the psychometric properties of the widely used NEO Five-Factor Inventory in a group of 419 patients with multiple sclerosis. Their objective was to determine if the NEO Five-Factor Inventory is reliable and valid in this population. Results showed adequate estimates of internal consistency, factorial validity, and self-informant correlation that support its use with patients with multiple sclerosis. Implications, limitations of the current study, and directions for future research are discussed.

[Reconsidering fatigue at the onset of multiple sclerosis]

Fatigue is a frequent symptom of multiple sclerosis (MS). It has been reported to varying degrees at all stages of the disease by 50 to 90% of all MS patients. Fatigue is now recognised as a disabling symptom which negatively impacts daily living. This symptom was underrated until recently but has now been included in clinical practice. Most fatigue scales have been developed in the English language and are culturally specific to their country of origin. The Fatigue Severity Scale is a one-dimensional nine-item scale which briefly assesses the impact of fatigue on the daily lives of MS patients. It has been widely used in different studies, even though it appears to be less relevant than the multi-dimensional 40-item Fatigue Impact Scale which was developed in Canada by Fisk et al (1994). The Fatigue Impact Scale is useful because it assesses different aspects of MS-related fatigue, such as the effects of fatigue on cognitive and physical activities and can include daily living. The Multiple Sclerosis Council for Clinical Practice Guidelines recommends the use of a 21-item Modified Fatigue Impact Scale which is a shortened version of the 40-item Fatigue Impact Scale. Using word-for-word translations of these scales into French would fail because the results would not be interpretable. We first translated and culturally adapted the Fatigue Impact Scale to French-speaking patients. We then evaluated the psychometric properties of this French version (EMIF-SEP). We used the EMIF-SEP scale to study fatigue in French MS patients. We found a significant correlation between higher EMIF-SEP total scores and higher EDSS scores; likewise physical dimension of the EMIF-SEP were linked to disability. But no correlations were found between the cognitive aspects of fatigue and disability. Other studies have failed to show any correlation between fatigue and disability. We suggest that this may be due to differences in sample size, or to the type of instrument used to quantify fatigue. As seen above, some tools do not allow for multi-dimensional assessment of fatigue. The EMIF-SEP scale is useful in that it allows for qualitative and quantitative assessment of fatigue.

Fatigued patients with multiple sclerosis have impaired central muscle activation

BACKGROUND

The pathogenesis of fatigue in multiple sclerosis (MS) is poorly understood.

OBJECTIVE

To elucidate the role of central motor activation we hypothesized that patients with primary fatigue have impaired central motor function and increased fatigability as compared to secondary fatigued and non-fatigued patients.

METHODS

Sixty patients with relapsing remitting MS and an Expanded Disability Status Scale score <or= 3.5 were recruited and grouped as fatigued (Fatigue Severity Scale (FSS) >or= 5.0) or non-fatigued (FSS <or= 4.0). Nineteen patients were primary fatigued, 20 secondary fatigued and 21 non-fatigued. Maximal voluntary contraction, central activation and peripheral activation were determined by percutaneous twitch interpolation of the right quadriceps muscle.

RESULTS

Maximal voluntary contraction was similar between groups but did relate to scores of fatigue. Peripheral activation was similar in all groups. Central activation was impaired in both groups of fatigued patients compared to non-fatigued patients being 0.96(0.05) in primary fatigued and 0.96(0.04) in secondary fatigued versus 0.99(0.1) in non-fatigued patients. The impairment of central motor activation was related to degree of fatigue in all patients. During fatiguing exercise there was a similar loss of strength, without any time differences between the three groups.

CONCLUSION

We conclude that impaired central motor activation is involved in MS-fatigue.

Neural correlates of cognitive fatigue in multiple sclerosis using functional MRI

Although fatigue is one of the major symptoms of persons with multiple sclerosis (MS), the behavioral and neural correlates are poorly understood. The present study utilized a novel approach to cognitive fatigue examining objective behavioral performance while simultaneously monitoring brain activity using fMRI. Fifteen persons with MS and 15 healthy controls were given 4 trials of a behavioral task assessing processing speed (mSDMT) during fMRI acquisition. It was hypothesized that individuals with MS would show an abnormal pattern of activity across time in specific brain areas previously hypothesized to subserve fatigue [Chaudhuri A, Behan PO. Fatigue and basal ganglia. J Neurol Sci 2000;179:34-42]. Specifically, it was hypothesized that persons with MS would show a greater increase in cerebral activation across time during behavioral performance than that seen in healthy controls, which was interpreted as fatigue. No difference in performance accuracy on the mSDMT was observed, although the MS group was significantly slower than controls. Behavioral alterations indicative of fatigue in the MS group were associated with increased activation in the basal ganglia, frontal areas including superior, medial, middle and inferior regions, parietal regions (precuneus and cuneus), thalamus and the occipital lobes. These data provide direct support for the Chaudhuri and Behan model of "central" fatigue which hypothesizes a specific role of the "non-motor" functions of the basal ganglia.

Cognitive impairment in multiple sclerosis: evidence-based analysis and recommendations

Cognitive impairment is common in multiple sclerosis (MS), occurring at all stages of the disease, and can be a major source of vocational disability, social impairment, and impoverished quality of life. Dysfunction in free recall from long-term memory, speed of information processing, working memory, and abstract reasoning are frequently observed in MS. Despite weak correlation with disease duration and physical disability status, the degree of cognitive impairment in MS has been related to the extent of topographically specific neuronal tissue damage and loss. Additional clinical factors including disease course, fatigue, affective disturbance, and medication can impact on the degree of MS-related cognitive impairment. We suggest that the symbol digits modalities test, paced auditory serial addition task, the clock drawing test and the MS neuropsychological screening questionnaire be considered as valid and relevant screening tests for cognitive impairment in MS.

fMRI changes in relapsing-remitting multiple sclerosis patients complaining of fatigue after IFNbeta-1a injection

If fatigue in multiple sclerosis (MS) is related to an abnormal activation of the sensorimotor brain network, the activity of such a network should vary with varying fatigue. We studied 22 patients treated with interferon beta 1a (IFNbeta-1a; Avonex, Biogen, Cambridge, MA) with no fatigue (10) and with reversible fatigue (12). fMRI examinations were performed: 1) the same day of IFNbeta-1a injection (no fatigue; entry), 2) the day after IFNbeta-1a injection (fatigue; time 1), and 3) 4 days after IFNbeta-1a injection (no fatigue; time 2). Patients performed a simple motor task with the right, clinically unaffected hand. At time 1, compared with entry and time 2, MS patients with reversible fatigue showed an increased activation of the thalamus bilaterally. In MS patients without fatigue thalamus was more activated at entry than at time 1. In both groups at entry the primary SMC and the SMA were more activated than at times 1 and 2. At entry and time 1, when compared to patients with reversible fatigue, those without showed increased activations of the SII. Conversely, patients with reversible fatigue had increased activations of the thalamus and of several regions of the frontal lobes. An abnormal recruitment of the fronto-thalamic circuitry is associated with IFNbeta-1a-induced fatigue in MS patients.

Effect of aerobic training on walking capacity and maximal exercise tolerance in patients with multiple sclerosis: a randomized crossover controlled study

BACKGROUND AND PURPOSE

Physical deconditioning is involved in the impaired exercise tolerance of patients with multiple sclerosis (MS), but data on the effects of aerobic training (AT) in this population are scanty. The purpose of this study was to compare the effects of an 8-week AT program on exercise capacity-in terms of walking capacity and maximum exercise tolerance, as well as its effects on fatigue and health-related quality of life-as compared with neurological rehabilitation (NR) in subjects with MS.

SUBJECTS AND METHODS

Nineteen subjects (14 female, 5 male; mean age [X+/-SD]=41+/-8 years) with mild to moderate disability secondary to MS participated in a randomized crossover controlled study. Eleven subjects (8 female, 3 male; mean age [X+/-SD]=44+/-6 years) completed the study.

RESULTS

After AT, but not NR, the subjects' walking distances and speeds during a self-paced walk were significantly improved, as were their maximum work rate, peak oxygen uptake, and oxygen pulse during cardiopulmonary exercise tests. The increases in peak oxygen uptake and maximum work rate, but not in walking capacity, were significantly higher after AT, as compared with after NR. Additionally, the subjects who were most disabled tended to benefit more from AT. There were no differences between AT and NR in effects on fatigue, and the results showed that AT may have partially affected health-related quality of life.

DISCUSSION AND CONCLUSION

The results suggest that AT is more effective than NR in improving maximum exercise tolerance and walking capacity in people with mild to moderate disability secondary to MS.

Habituation and Dishabituation of P300

OBJECTIVE

We aimed to see the consequences of habituation and posthabituation by means of repeatedly measuring the effects over a longer period.

METHOD

The study was performed on 27 healthy volunteers. The event-related potentials were recorded from the Fz, the Cz, and the Pz electrode sites. The rare tone-frequent tone probability ratio was 20%. All subjects were asked to press a button when they heard a rare tone. The test was continued until 20 artifact-free rare tones were averaged, which was accepted as 1 trial block. After 10 trial blocks were obtained in a sequential manner, the test was completed.

RESULT

This study has indicated that P300 amplitudes decrease with repeated stimulations, that is, there is a habituation period. As the test continues, the speed of amplitude decrease slows down and after a while it even starts to increase: that is, a dishabituation occurs.

CONCLUSIONS

It is very likely that this habituation relates to a period of learning and dishabituation relates to a period of mental fatigue. In these processes, changes of amplitude and latency values reflect changes in amount of neuronal activation.

[Fatigability evaluation on multiple sclerosis patients by using a hand held dynamometer]

Fatigue is one of the most common disabling symptoms in multiple sclerosis (MS). The aim of this study was to evaluate the fatigability on patients with MS by the application of hand grip isotonic and isometric exercises with dynamometer. As results the fatigability, the isometric strength and time were statistically similar in the control group and in MS. We conclude that although fatigue is a frequent subjective complaint on MS, the fatigability and the recover after exercises seems to be normal.

Cognitive impairment and neurophysiological correlates in MS

Cognitive impairment in multiple sclerosis (MS) has received considerable interest over the last decades. Heterogeneous patterns of cognitive dysfunction have been reported in literature in relation to the subtype of the disease and the severity of specific cognitive domains affected. Event related potentials (ERPs), especially P300, have been employed to evaluate the cognitive decline in MS and neurophysiological findings agree with data obtained by neuropsychological testing. The objectivity, the reliability and the easy administration are the main features of ERP technique but more specific attention and memory tasks are needed to enhance the clinical value of the methodology. Moreover, ERP recording has the advantage of being feasible even in severe disabled patients. Finally, longitudinal ERP studies are required to investigate the natural course of cognitive dysfunction in MS, to estimate the prognostic value of subclinical defects in different clinical form of the disease and to evaluate clinical benefits of therapeutic and rehabilitative interventions.

[Pathophysiology and treatment of fatigue in multiple sclerosis]

Patients suffering from multiple sclerosis (MS) frequently complain of fatigue (53 to 92 percent depending on studies). Fatigue can be one of the most disabling symptoms of MS and presents as physical or mental fatigue in daily living activities. Besides this permanent feeling of exhaustion, MS patients can suffer from an abnormal tiredness and lack of energy after a given motor or mental task, which defines fatigability. A number of studies explored the origins of fatigue and fatigability by means of subjective and objective tools. The implication of central nervous system dysfunctions has been established in several studies; however the contribution of peripheral nervous system factors and systemic abnormalities associated with inflammatory and immunological parameters was also suggested. The aim of this review is to present the different types of fatigue and fatigability occurring in MS patients, their origins, the investigation tools which allow the quantification of fatigue and fatigability and characterization of their mechanisms. The currently available therapeutic strategies that have been proposed to relieve this disabling symptom are presented.

Therapy-induced plasticity of cognitive functions in MS patients: insights from fMRI

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system whose pathological mechanisms are still not completely understood. Physical as well as cognitive deterioration are consequences within the disease process that have an extensive impact on the patient's quality of life. Therefore, understanding the functional background of spontaneous as well as induced remission is of high relevance. Studies on visualization of therapeutic effects of pharmacological or cognitive treatment by functional magnetic resonance imaging (fMRI) are still rare. From fMRI studies on focal brain lesions hypotheses on mechanisms of brain reorganization can be derived. This contribution will first give an overview of the existing studies using fMRI in MS, on cognitive decline, on cognitive treatment studies and its therapeutic effects on behavioural readouts in MS, and on therapy-induced brain plasticity and its possible visualization by fMRI. Results of a study on correlating the effects of cognitive training with changes in brain organization in patients with mild to severe cognitive impairment will be reported.

The relationship between fatigue and depression, and event-related potentials in epileptics

The aim of the present study was to establish the rate of fatigue and the relationship between fatigue, depression, and P300 in people with epilepsy. We compared Fatigue Severity Scale (FSS) and Beck Depression Inventory (BDI) scores and event-related potentials (ERPs) of people with epilepsy (n=73) with those of controls (n=31). The rate of fatigue was found to be 42.4%, and fatigue and depression were positively correlated. There was an interaction between fatigue and ERPs, but the effect of ERPs on fatigue was greater. While polytherapy was a major factor affecting ERPs, depression had no effect on ERPs in people with epilepsy. The data suggest that fatigue is an important finding and is strongly correlated with cognitive processes and depression. Polytherapy contributed to cognitive disturbances and, hence, fatigue, whereas depression had no effect on cognitive processes in people with epilepsy.

Fatigue in multiple sclerosis: A rational approach to evaluation and treatment

With the publication of the Multiple Sclerosis Council Guideline on the management of multiple sclerosis (MS) fatigue, there has been increased appreciation for the role fatigue can play in MS. Secondary fatigue is fatigue caused by other etiologies than those directly related to MS. Once these causes are ruled out, fatigue is related to MS. Secondary MS-related fatigue comes as result of the symptoms of MS that drain energy. Once secondary MS causes are ruled out, then the patient is deemed as having primary MS fatigue. Fatigue management is both nonpharmacologic and pharmacologic. Occupational therapists are the major allied health providers that address the role fatigue plays in MS patients. Over the past two decades, numerous clinical trials have been conducted on drugs for treating MS-related fatigue. Of these agents, amantadine has been studied for the longest period, and has shown efficacy in about one third of patients with MS-related fatigue on several commonly used scales. Two randomized -trials of the central nervous system stimulant pemoline have yielded unimpressive results; efficacy was seen at higher doses but coupled with an unacceptable risk of adverse events. The wake-promoting agent modafinil is the only agent to show efficacy compared with placebo on the Fatigue Severity Scale, a measure that is highly resistant to "impulse answering" and is thus viewed as one of the most difficult scales on which to show -benefit. This article reviews fatigue in MS and proposes a rational strategy for evaluation and management of this most common MS symptom.

Management of fatigue in patients with multiple sclerosis

As long as no causal treatment is available for multiple sclerosis (MS), and as long as only some patients with MS respond to immunomodulators, symptomatic treatment is of paramount importance. Fatigue is the most common symptom of MS and is associated with a reduced quality of life. It is described as the worst symptom of their disease by 50-60% of patients. The first step in managing MS-related fatigue is identifying and eliminating any secondary causes. Primary fatigue syndrome can be alleviated with drug treatment in many cases. Modafinil has been shown to be effective in some studies, and amantadine is an alternative for patients who do not respond to or cannot tolerate modafinil. The nonpharmacological management of fatigue in MS includes inpatient rehabilitation and aerobic endurance exercise. This article describes the pathophysiology, diagnosis and treatment of MS-related fatigue--the most common symptom of MS.

Exercise and Multiple Sclerosis

The pathophysiology of multiple sclerosis (MS) is characterised by fatigue, motor weakness, spasticity, poor balance, heat sensitivity and mental depression. Also, MS symptoms may lead to physical inactivity associated with the development of secondary diseases. Persons with MS are thus challenged by their disability when attempting to pursue an active lifestyle compatible with health-related fitness. Although exercise prescription is gaining favour as a therapeutic strategy to minimise the loss of functional capacity in chronic diseases, it remains under-utilised as an intervention strategy in the MS population. However, a growing number of studies indicate that exercise in patients with mild-to-moderate MS provides similar fitness and psychological benefits as it does in healthy controls. We reviewed numerous studies describing the responses of selected MS patients to acute and chronic exercise compared with healthy controls. All training studies reported positive outcomes that outweighed potential adverse effects of the exercise intervention. Based on our review, this article highlights the role of exercise prescription in the multidisciplinary approach to MS disease management for improving and maintaining functional capacity. Despite the often unpredictable clinical course of MS, exercise programmes designed to increase cardiorespiratory fitness, muscle strength and mobility provide benefits that enhance lifestyle activity and quality of life while reducing risk of secondary disorders. Recommendations for the evaluation of cardiorespiratory fitness, muscle performance and flexibility are presented as well as basic guidelines for individualised exercise testing and training in MS. Special considerations for exercise, including medical management concerns, programme modifications and supervision, in the MS population are discussed.

[Therapy of day time fatigue in patients with multiple sclerosis]

Fatigue is the most common symptom of multiple sclerosis. 75%-90% of patients with multiple sclerosis report having fatigue, and 50%-60% describe it as the worst symptom of their disease. Fatigue is significantly associated with reduced quality of life and is also a major reason for unemployment, especially for patients with otherwise minor disability. The mechanisms underlying abnormal levels of fatigue in multiple sclerosis are poorly understood. To date, drug treatment has been only partially successful in alleviating fatigue, and effects vary widely from patient to patient. Amantadine and modafinil showed to be effective in the treatment of fatigue in some studies. Non-pharmacological management of fatigue in multiple sclerosis includes inpatient rehabilitation and endurance training. There is also evidence, that pulsing electromagnetic fields may improve fatigue associated with multiple sclerosis. This paper summarizes the recent literature on pathophysiology, diagnosis and therapy of the most common symptom of multiple sclerosis.

Fatigue in multiple sclerosis: definition, pathophysiology and treatment

Fatigue is a common disabling symptom of multiple sclerosis (MS). It is often considered a state of exhaustion distinct from depressed mood or physical weakness. Fatigue can be assessed by either self-report scales or performance-based measures; however, neither method captures all features of fatigue. Fatigue in MS frequently leads to unemployment. It is associated with a sense of loss of control over one's environment, low positive affect, psychological distress and neurological impairment. To date there is no reproducible neuroimaging marker or biological correlate that has been identified. Proposed pathological mechanisms of fatigue in MS include neuronal factors such as dysfunction of premotor, limbic, basal ganglia or hypothalamic areas; disruption of the neuroendrocrine axis leading to low arousal; alteration in serotoninergic pathways; changes in neurotransmitter levels; and altered CNS functioning caused by a disruption of the immune response. Treatment of fatigue is best approached in a multidisciplinary fashion that incorporates nonpharmacological interventions as well as medication. Amantadine and modafinil are among the most commonly used medications for fatigue associated with MS. Both medications have been studied with positive results in controlled clinical trials. Additional research towards measurement and pathogenesis of fatigue will hopefully lead to improved therapies.

The influence of fatigue on health-related quality of life in patients with Parkinson's disease

OBJECTIVE

To examine the correlation between fatigue and health-related quality of life (HRQL) in patients with Parkinson's disease (PD).

PATIENTS AND METHODS

Sixty-six patients with idiopathic PD. The patients did not have a depressive mood disorder or cognitive impairment. Fatigue was measured by the Fatigue Severity Scale (FSS). HRQL was measured by the Parkinson's Disease Questionnaire (PDQ-39) and the Short-Form 36 (SF-36).

RESULTS

Thirty-three (50%) of the patients had significant fatigue. Patients with fatigue had a more advanced disease than those without fatigue, measured by the UPDRS scale, including a higher Hoehn and Yahr stage and lower Schwab and England score. Patients with fatigue reported more distress in the dimensions of emotional well-being and mobility (PDQ-39) and also had a significantly higher PDQ summary index. On the SF-36 patients with fatigue reported more problems in the areas of physical functioning, role limitation (physical), social functioning and vitality. Correlations between the FSS and the HRQL scales were highest for the summary index of PDQ-39 and in the dimensions of ADL, mobility and emotional well-being (PDQ-39) and physical functioning, role limitation (physical), social functioning, general health and vitality (SF-36).

CONCLUSIONS

PD has a substantial negative impact on HRQL. We found a strong correlation between fatigue and high distress scores on HRQL scales in a population of patients with PD who were not depressed or demented. The diversity of symptoms and high prevalence of non-motor features, including fatigue, is important to take into account in our efforts to optimize treatment and care for this patient group.

Measuring fatigue in patients with Parkinson's disease - the Fatigue Severity Scale

The objective was to compare the prevalence and severity of fatigue in patients with Parkinson's disease (PD) with that in two control groups, one consisting of randomly chosen control subjects of the same age and sex distribution and the other consisting of patients with coxarthrosis waiting to receive total hip replacement. We also explored the possible correlation of demographic and clinical data to the presence and severity of fatigue. Sixty-six patients with PD, 131 randomly chosen controls and 79 patients with coxarthrosis, waiting to receive total hip replacement, were evaluated for fatigue. Patients and controls with a depressive mood disorder or cognitive impairment had been excluded from the study. Fatigue was measured by the Fatigue Severity Scale (FSS). For the patients with PD the mean total FSS score was 4.1, compared with 2.7 amongst the randomly chosen control group and 2.9 in the group consisting of patients with coxarthrosis. Fifty per cent of the patients with PD had a mean total FSS score of 4 or higher, compared with 25% in both of the two control groups. There was no correlation between pain, presence of self-reported nocturnal sleep disorders or duration of PD and fatigue. The patients with fatigue did have a more advanced disease, measured both by Unified Parkinson's Disease Rating Scale score and Hoehn and Yahr stage. Although the univariate analyses indicated that more severe parkinsonism was correlated to the symptom, the multivariate analysis showed that none of the studied variables were significant explanatory factors for fatigue. Fatigue is a common symptom in patients with PD without depression or dementia. The study indicates that fatigue is an independent symptom of the disease without relation to other motor or non-motor symptoms.

Construction and validation of a fatigue impact scale for daily administration (D-FIS)

The fatigue impact scale (FIS) was developed previously as a symptom-specific profile measure of health-related quality of life (HRQoL) for use in medical conditions in which fatigue is a prominent chronic symptom. Thus, it was not developed to be a responsive measure of daily changes in fatigue. This study describes the development and initial validation of an adaptation of the FIS for daily use. Items for the daily fatigue impact scale (D-FIS) were selected from the pool of original FIS items through Rasch analyses of existing data. The reduced-item FIS was administered to a sample of 93 subjects with flu-like illness, 25 of whom were followed for a 21-day period. Rasch analyses were used to further reduce the scale to a minimum number of items that represented a unidimensional measure of self-reported fatigue impact. This 8-item D-FIS demonstrated good relations to flu symptom ratings and to other general health ratings. It also proved to be a responsive measure of change in reported fatigue impact for subjects who were followed longitudinally. This initial validation study indicates that the D-FIS has considerable promise as a valid measure of the subjective daily experience of fatigue.

Autonomic instability, as measured by pupillary unrest, is not associated with multiple sclerosis fatigue severity

Multiple sclerosis (MS) fatigue is one of the most common symptoms in MS, but its pathophysiology is still not understood Sympathovagal imbalance was suggested as a reason for fatigue in chronic fatigue syndrome. We examined the role of an imbalance in the central autonomic nervous system (ANS) as a cause of MS fatigue in 51 MS patients and a control group of 22 healthy volunteers. Fatigue was assessed with the revised MS Fatigue Severity Scale (FSS) and the Modified Fatigue Impact Scale (MFIS). Depression was evaluated with the Beck Depression Inventory (BDI). Disintegration of the central ANS expressed by pupillary fatigue waves was measured with pupillography and documented in the pupillary unrest index (PUI). All subjects had less than five points on the seven-point Stanford Sleepiness Scale and were therefore not sleepy. MS patients had significant higher mean FSS scores (p=0.001) and mean MFIS scores (p=0.003) than our control group. Mean BDI scores were significant higher (p=0.001) in the MS group, but were in the lowest score range (0-10 points) in both groups. Surprisingly, we found a statistically significant inverse correlation between PUI values and either FSS scores (p=0.001; r=-0.521) or MFIS scores (p=0.002; r=-0.423) in the MS group, but not in healthy participants. We therefore conclude that autonomic instability, as measured by pupillary unrest is not associated with MS fatigue severity.

Functional magnetic resonance imaging correlates of fatigue in multiple sclerosis

Although fatigue is a common and troublesome symptom of multiple sclerosis (MS), its pathogenesis is poorly understood. In this study, we used functional magnetic resonance imaging (fMRI) to test whether a different pattern of movement-associated cortical and subcortical activations might contribute to the development of fatigue in patients with MS. We obtained fMRI during the execution of a simple motor task with completely normally functioning hands from 15 MS patients with fatigue (F), 14 MS patients without fatigue (NF), and 15 sex- and age-matched healthy volunteers. F and NF MS patients were also matched for major clinical and MRI variables. FMRI data were analyzed using statistical parametric mapping. In all patients, severity of fatigue was rated using the Fatigue Severity Scale (FSS). Compared to healthy subjects, MS patients showed more significant activations of the contralateral primary somatomotor cortex, the contralateral ascending limb of the Sylvian fissure, the contralateral intraparietal sulcus (IPS), the contralateral supplementary motor area, and the ipsilateral and contralateral cingulate motor area (CMA). Compared to F MS patients, NF patients showed more significant activations of the ipsilateral cerebellar hemisphere, the ipsilateral rolandic operculum, the ipsilateral precuneus, the contralateral thalamus, and the contralateral middle frontal gyrus. In contrast, F MS patients had a more significant activation of the contralateral CMA. Significant inverse correlations were found between FSS scores and relative activations of the contralateral IPS (r = -0.63), ipsilateral rolandic operculum (r = -0.61), and thalamus (r = -0.62). This study provides additional evidence that fatigue in MS is related to impaired interactions between functionally related cortical and subcortical areas. It also suggests that fMRI might be a valuable tool to monitor the efficacy of treatment aimed at reducing MS-related fatigue.

Fatigue in Multiple Sclerosis Is Associated with Abnormal Cortical Activation to Voluntary Movement—EEG Evidence

Converging evidence is consistent with the view that fatigue in Multiple Sclerosis is independent from pyramidal tract involvement, suggesting a possible involvement of frontal areas. During voluntary movement, changes of the EEG rhythms can be observed over sensorimotor areas. Event-related desynchronization (ERD) of the 10 and 20 Hz frequency bands occurs during motor planning and execution and is followed after movement termination by event-related synchronization (ERS), expressing cortical idling or inhibition. We evaluated the pattern of cortical activation to voluntary movement in MS patients complaining of fatigue assessed using the Fatigue Severity Scale. Fifteen MS patients complaining of fatigue, 18 MS patients without fatigue, and 14 normal controls were studied. The two patients groups were similar for age, sex, disease duration, and were not disabled (score <1.5 at the Expanded Disability Status Scale). Twenty-nine channel EEG was recorded during about 60 self-paced extensions of the right thumb. The onset latency and amount of the contralateral sensorimotor (C3 electrode) 10 and 18--22 Hz ERD were similar in the three groups. ERD was more widespread anteriorly in the fatigue group compared with normal controls (P < 0.01 over Fz electrode). Postmovement contralateral sensorimotor 18--22 Hz ERS was significantly lower in fatigue MS patients compared with normal subjects (P < 0.005) and with nonfatigue MS patients (P = 0.02). These findings are consistent with a central origin of fatigue in MS and indicate cortical dysfunction even during a simple motor task, resulting in hyperactivity during movement execution and failure of the inhibitory mechanisms intervening after movement termination.

Modalities of fatigue in multiple sclerosis: correlation with clinical and biological factors

Although different factors are probably involved in the etiology of fatigue in multiple sclerosis patients, no definite mechanism has been proposed. We have proposed that fatigue is a complex symptom that includes three clinical different entities (asthenia, fatigability and worsening of symptoms with effort). The goal of this study is to demonstrate if there is a peculiar mechanism for each of the different varieties of fatigue. A control sample of 155 patients (105 women, 50 men) with clinically definite MS was studied. Fatigue was measured using the Fatigue Descriptive Scale (FDS) and the Fatigue Severity Scale (FSS). Treatment, depression, anxiety, sleep and cellular immune status were studied too. Fatigue was a symptom in 118 patients (76.13%); 26 patients (22.03%) described it as asthenia (fatigue at rest); 85 patients (72.03%) as fatigability (fatigue with exercise), and seven patients (5.9%) as worsening of symptoms. The severity of pyramidal involvement was significantly more severe in patients suffering from fatigue; some immunological parameters were associated with fatigue as well. The discriminant analysis of the data shows that some of the immunoactivation parameters are associated with asthenia (F=21.5, P<0.001), and pyramidal tract involvement is associated with fatigability (F=10.5, P<0.001). Sleep disorders, anxiety and depression were linked with fatigue in a few patients. No relationship with treatment was proven. In conclusion, fatigue in MS seems to be a heterogeneous entity. Asthenia and fatigability may be different clinical entities. Certain immunoactivation parameters correlate with the presence of asthenia while pyramidal involvement is associated with fatigability.

Fatigue in patients with Parkinson's disease

OBJECTIVE

To compare the prevalence of fatigue in patients with Parkinson's disease (PD) with that in healthy elderly people and to explore the suggestion that fatigue is an independent symptom of PD.

DESIGN

Questionnaire survey.

SETTING

Community-based population.

PATIENTS AND CONTROL SUBJECTS

233 patients derived from a prevalence study in the county of Rogaland, Norway and 100 healthy elderly people with the same age and sex distribution as the patients with PD.

MAIN OUTCOME MEASURE

A score for fatigue was obtained by combining the results from the rating scale for low energy in the Nottingham Health Profile (NHP) with the results obtained from a 7-point scale devised to evaluate fatigue.

RESULTS

44.2% of the patients with PD and 18% of the healthy elderly control subjects reported fatigue. Fatigue was associated with depression, dementia, disease severity, disease duration, levodopa dose, and the use of sleeping pills. In a multivariate analysis, only depressive symptoms reached statistical significance. The prevalence of fatigue in patients with PD who were not depressed, demented, or had a sleeping disturbance was similar to that found in the total PD population.

CONCLUSION

Fatigue is a common symptom in PD. Although fatigue correlated with depressive symptoms, patients with PD who did not have depression, dementia, or sleep disturbances also reported a high prevalence of this symptom. This supports the hypothesis that fatigue is an independent symptom of PD overlapping with, but not causally related to, the concurrence of depressive symptoms.

Interhemispheric transfer in normals and acallosals: latency adjusted evoked potential averaging

Interhemispheric transfer time (IHTT) can be estimated from visual evoked potentials (EPs). Latency adjusted averaging (LAA) produces EPs which have enhanced components. LAA also provides estimates of EP latency variance and signal-to-noise ratio (S/N). LAA was tested in analysis of EP-IHTT in normal and acallosal subjects. It was hypothesized that in normals S/N and latency variance would reveal signal degradation resulting from interhemispheric transfer. LAA in normals replicated IHTT findings for both P1 and N1 latency. Latency variance did not increase for cross-callosal measures, whereas the S/N measure showed significant EP degradation due to callosal transfer. EPs from five subjects with callosal absence (two commissurotomy; two complete and one partial callosal agenesis) showed significantly larger than normal latency variability, as well as decreased S/N ratios, for cross-hemisphere visual EPs. Results support the value of LAA in EP research on adequacy of hemispheric interactions in clinical populations.

Walking and fatigue in multiple sclerosis: the role of the corticospinal system

Transcranial magnetic stimulation was used to study motor evoked potentials (MEPs) of leg muscles in controls and patients with multiple sclerosis (MS) before and after walking. In controls, MEP areas were significantly reduced after walking. A similar or greater reduction was seen in most patients, although there was a wide range of values. The M waves were unchanged. We conclude that walking induces functional changes of the corticospinal system and/or connected neurons contributing to central fatigue, especially in patients with MS.