Quantitative assessment of motor fatigue and strength in MS

Motor fatigue measurement by distance-induced slow down of walking speed in multiple sclerosis

Background and rationale

Motor fatigue and ambulation impairment are prominent clinical features of people with multiple sclerosis (pMS). We hypothesized that a multimodal and comparative assessment of walking speed on short and long distance would allow a better delineation and quantification of gait fatigability in pMS. Our objectives were to compare 4 walking paradigms: the timed 25-foot walk (T25FW), a corrected version of the T25FW with dynamic start (T25FW⁺), the timed 100-meter walk (T100MW) and the timed 500-meter walk (T500MW).

Methods

Thirty controls and 81 pMS performed the 4 walking tests in a single study visit.

Results

The 4 walking tests were performed with a slower WS in pMS compared to controls even in subgroups with minimal disability. The finishing speed of the last 100-meter of the T500MW was the slowest measurable WS whereas the T25FW⁺ provided the fastest measurable WS. The ratio between such slowest and fastest WS (Deceleration Index, DI) was significantly lower only in pMS with EDSS 4.0–6.0, a pyramidal or cerebellar functional system score reaching 3 or a maximum reported walking distance ≤4000 m.

Conclusion

The motor fatigue which triggers gait deceleration over a sustained effort in pMS can be measured by the WS ratio between performances on a very short distance and the finishing pace on a longer more demanding task. The absolute walking speed is abnormal early in MS whatever the distance of effort when patients are unaware of ambulation impairment. In contrast, the DI-measured ambulation fatigability appears to take place later in the disease course.

Exercise in multiple sclerosis -- an integral component of disease management

Multiple sclerosis (MS) is the most common chronic inflammatory disorder of the central nervous system (CNS) in young adults. The disease causes a wide range of symptoms depending on the localization and characteristics of the CNS pathology. In addition to drug-based immunomodulatory treatment, both drug-based and non-drug approaches are established as complementary strategies to alleviate existing symptoms and to prevent secondary diseases. In particular, physical therapy like exercise and physiotherapy can be customized to the individual patient's needs and has the potential to improve the individual outcome. However, high quality systematic data on physical therapy in MS are rare. This article summarizes the current knowledge on the influence of physical activity and exercise on disease-related symptoms and physical restrictions in MS patients. Other treatment strategies such as drug treatments or cognitive training were deliberately excluded for the purposes of this article.

Fatigue perceived by multiple sclerosis patients is associated with muscle fatigue

BACKGROUND

Fatigue is a debilitating symptom in multiple sclerosis (MS). Previous studies showed no association between fatigue as perceived by the patient and physiological measures of fatigability.

OBJECTIVE

The authors investigated associations between perceived fatigue and measures of fatigability after correction for differences in maximal voluntary contraction (MVC).

METHODS

A total of 20 people with relapsing-remitting MS with an Extended Disability Severity Score less than 5.5 and 20 healthy controls filled out the Fatigue Severity Score questionnaire of perceived fatigue. The authors obtained the MVC from the first dorsal interosseus muscle, voluntary muscle activation, and force decline during a sustained MVC (124 s, muscle fatigue).

RESULTS

Patients perceived increased levels of fatigue compared with controls (P < .001). Although patients and controls developed similar amounts of muscle fatigue during the sustained contraction, a linear regression model that included both muscle fatigue and MVC was positively associated with perceived fatigue in patients only (R (2) = 0.45; P = .01). Voluntary activation during the sustained contraction was negatively associated with perceived fatigue (R (2) = 0.25; P = .02).

CONCLUSION

The data indicate that fatigue perceived by MS patients is associated with measures of fatigability. This observation helps in the understanding of mechanisms underlying the increased levels of fatigue perceived by MS patients. These data also emphasize that for comparison of fatigue-related parameters between groups, correction for individual maximal force is essential.

Symptomatic management in multiple sclerosis

The development of immunomodulatory therapies for multiple sclerosis (MS) has had significant impact in altering the natural history of the disease. Although these agents reduce relapse rate and MRI-associated disease activity, they are only partially effective and do not ameliorate irreversible axonal injury, which produces much of the symptomatic burden of MS. Treatment of MS-associated symptoms remains an essential cornerstone of comprehensive care of patients with MS and, arguably, more favorably enhances quality of life than do the disease-modifying medications. This article reviews strategies of symptom management in patients with MS.

Using the force-time curve to determine sincerity of effort in people with upper extremity injuries

This was a prospective cohort study. In a previous study, the slopes of the force-time (F-T) curve were shown to differentiate between maximal and submaximal grip effort in healthy participants. The objective of the study was to examine if the slopes of the F-T curve can determine the sincerity of effort in people with upper extremity injuries. Forty participants with unilateral upper extremity injury performed maximal and submaximal grip efforts. The F-T curve was recorded, and the slopes of the force-generation and force-decay phases were calculated. Repeated-measures analysis of variance revealed significantly steeper slopes for maximal than those for submaximal efforts. However, receiver operating characteristic curves showed that, at best, the slope of the force-generation phase yielded overall error rates of 55% for women and 60% for men. Therefore, sensitivity and specificity values were insufficient to effectively differentiate maximal from submaximal efforts. The slopes of the F-T curve did not validly measure the sincerity of effort in participants with upper extremity injury, perhaps, because they were protective of their injured hand and, thus, exerted only submaximal effort even at their best grip attempt.

LEVEL OF EVIDENCE

Not applicable.

Comparison of the Timed 25-Foot and the 100-Meter Walk as Performance Measures in Multiple Sclerosis

Background. Ambulation impairment is a major component of physical disability in multiple sclerosis (MS) and a major target of rehabilitation programs. Outcome measures commonly used to evaluate walking capacities suffer from several limitations. Objectives. To define and validate a new test that would overcome the limitations of current gait evaluations in MS and ultimately better correlate with the maximum walking distance (MWD). Methods. The authors developed the Timed 100-Meter Walk Test (T100MW), which was compared with the Timed 25-Foot Walk Test (T25FW). For the T100MW, the subject is invited to walk 100 m as fast as he/she can. In MS patients and healthy control volunteers, the authors measured the test–retest and interrater intraclass correlation coefficient. Spearman rank correlations were obtained between the T25FW, the T100MW, the Expanded Disability Status Scale (EDSS), and the MWD. The coefficient of variation, Bland–Altman plots, the coefficient of determination, and the area under the receiver operator characteristic curve were measured. The mean walking speed (MWS) was compared between the 2 tests. Results. A total of 141 MS patients and 104 healthy control volunteers were assessed. Minor differences favoring the T100MW over the T25FW were observed. Interestingly, the authors demonstrated a paradoxically higher MWS on a long (T100MW) rather than on a short distance walk test (T25FW). Conclusion. The T25FW and T100MW displayed subtle differences of reproducibility, variability, and correlation with MWD favoring the T100MW. The maximum walking speed of MS patients may be poorly estimated by the T25FW since MS patients were shown to walk faster over a longer distance.

Wireless medical sensor measurements of fatigue in patients with multiple sclerosis

This paper presents our experience with developing a portable wireless medical sensor device. We use National Instruments (NI) devices and LabView for measurements studying fatigue of patients suffering multiple sclerosis (MS). Fatigue is a very frequent symptom perceived by MS patients, but the disease mechanism is poorly understood. Many efforts have been made to increase the understanding of this complex phenomenon. It has been found that fatigue might be associated with abnormalities in various anatomical brain areas. Also some secondary factors, not directly related to the disease, such as depression, sleep disorder, severe pain, use of medication and psychological factors might be of importance. However, the relationship with physiological parameters and motion activities in MS patients with fatigue across time are still unknown. Therefore, we hypothesize that we could provide a new assessment of fatigue in MS besides the questionnaires that are currently employed. Furthermore we can discover more secondary factors contributing to fatigue by measuring and monitoring a battery of physiological parameters over an extended time span (e.g. 48 hours) in MS patients without disturbing their normal life behavior. We have developed wireless medical sensor devices and conducted the following, namely Electrocardiograph, body skin temperature, eye movement detection, Electromyograph, motion detection, and muscle strength. In this paper, we describe the technology and design procedures of each measurement and present data from the first two test patients.

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

Fatigue is a feature of several chronic diseases of the central and peripheral nervous system. The pathophysiology of central fatigue is complex and often not well-defined. In contrast, peripheral fatigue is more objectively defined and measured. Fatigue can be part of the primary disease process, but there are often contributions from comorbid factors such as depression, sleep disturbance, medication, or deconditioning. Multiple sclerosis (MS) offers an example of central fatigue. More than 40% of MS patients complain of fatigue. Validated questionnaires are used to assess fatigue severity and comorbid factors. Although fatigue is believed to be a primary process in MS, depression and sleep disturbance are often comorbid problems. Magnetic resonance imaging (MRI), positron emission tomography, and functional MRI studies suggest that fatigue is related to gray matter disease, particularly of the cerebral cortex, but also of the thalamus and caudate. Disruption of impulse propagation from demyelination is also a likely factor. It is uncertain if pro-inflammatory cytokines have a specific effect on the genesis of MS fatigue. Several medications have been reported to alleviate fatigue in MS, but controlled studies show contradictory results. Treatment of depression and sleep disturbance, use of exercise programs and rehabilitation therapies as well as treatment of other comorbid conditions is necessary for optimal alleviation of fatigue. Myasthenia gravis (MG) patients exhibit peripheral fatigue. In contrast to MS, the mechanism of weakness and fatigue in MG is well-defined. Antibodies to the postsynaptic acetylcholine receptor at the myoneural junction cause diminution of the force of muscle contractions. This leads to a feeling of fatigue. MG treatments increase the availability of acetylcholine and reduce antibody formation. Evaluation for comorbid conditions, especially thymoma and hyperthyroidism, are mandatory in patients with MG.

Muscle fiber size increases following resistance training in multiple sclerosis

Objective: To test the hypothesis that lower body progressive resistance training (PRT) leads to an increase of the muscle fiber cross-sectional area (CSA) and a shift in the proportion of fiber types in patients with multiple sclerosis (MS).

Methods: The present study was a two-arm, randomized controlled trial (RCT). Thirty-eight MS patients (Expanded Disability Status Scale (EDSS) 3—5.5) were randomized to a PRT group (Exercise, n = 19) or a control group (Control, n = 19). The Exercise group performed a biweekly 12-week lower body PRT program [five exercises progressing from 15RM (Repetition Maximum) towards 8RM], whereas the Control group maintained their usual daily activity level during the trial period. Muscle biopsies from vastus lateralis were taken before (pre) and after the trial (post). Thigh volume (TV) was estimated from anthropometric measurements. Isokinetic muscle strength of the knee extensors (KE) and flexors (KF) were evaluated at slow (90°/s) and fast (180°/s) angular velocities.

Results: In the Exercise group the mean CSA of all muscle fibers (7.9 ± 15.4% vs. -3.5 ± 9.0%, p = 0.03) and of type II muscle fibers (14.0 ± 19.4% vs. -2.6 ± 15.5%, p = 0.02) increased in comparison with the Control group. No changes occurred in the proportion of fiber types in the Exercise group. Neither was there any change in total TV. Isokinetic strength at KE180, KF90 and KF180 improved significantly after PRT when compared with the control group (10.2—21.3%, p ≤ 0.02).

Conclusions: We conclude that progressive resistance training induces a compensatory increase of muscle fiber size in patients with the central nervous system disorder, multiple sclerosis.

Correlation of self-assessed fatigue and alertness in multiple sclerosis

Background: Fatigue is the most common symptom in multiple sclerosis patients, but is difficult to measure; quantification thus relies on self-assessed questionnaires.

Objective: To evaluate a battery of neuropsychological tests regarding their capacity to objectify self-reported fatigue.

Methods: We assessed the correlation between age, gender, education, Kurtzke’s Expanded Disability Status Scale, depression, fatigue and neuropsychological testing using a cross-sectional approach in 110 multiple sclerosis patients. Fatigue was measured with the Fatigue Severity Scale. Cognition was measured using a series of neuropsychological tests including three subtests of the Test of Attentional Performance, the Brief Repeatable Battery of Neuropsychological Tests and the Faces Symbol Test.

Results: According to the Fatigue Severity Scale 51.4% of the cohort were fatigued (scores ≥4). Age, education and depression showed a significant correlation with the Fatigue Severity Scale. Only 5.5% of the cohort exhibited cognitive impairment in the Brief Repeatable Battery of Neuropsychological Tests scores. After correction for age, education, Expanded Disability Status Scale and depression, Fatigue Severity Scale scores were an independent predictor of performance in the alertness subtest of the Test of Attentional Performance (standardized coefficient beta = 0.298, p = 0.014).

Conclusion: The alertness subtest of the Test of Attentional Performance may offer an objective method of evaluating self-reported fatigue, and may therefore — in addition to the Fatigue Severity Scale — be a suitable tool for the assessment of multiple sclerosis patients complaining of fatigue.

Possible clinical outcome measures for clinical trials in patients with multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease with both clinical and pathological heterogeneity. The complexity of the MS population has offered challenges to the measurement of MS disease progression in therapeutic trials. The current standard clinical outcome measures are relapse rate, Expanded Disability Severity Scale (EDSS), and the MS Functional Composite (MSFC). These measures each have strengths and some weakness. Two additional measures, the six-minute walk and accelerometry, show promise in augmenting current measures. MS therapeutics is a quickly advancing field which requires sensitive clinical outcome measures that can detect small changes in disability that reliably reflect long-term changes in sustained disease progression in a complex population. A single clinical outcome measure of sustained disease progression may remain elusive. Rather, an integration of current and new outcome measures may be most appropriate and utilization of different measures depending on the MS population and stage of the disease may be preferred.

International development of the Unidimensional Fatigue Impact Scale (U-FIS)

OBJECTIVE

The 22-item Unidimensional Fatigue Impact Scale (U-FIS) provides an index of the impact of fatigue on patients with multiple sclerosis (MS). The objective is to produce eight new language versions of the U-FIS: Canadian-English, Canadian-French, French, German, Italian, Spanish, Swedish, and US-English.

METHODS

The U-FIS was translated via two translation panels. Cognitive debriefing interviews conducted with patients in each country assessed face and content validity. Scaling and psychometric properties were assessed via survey data with patients in each country completing the U-FIS, Nottingham Health Profile (NHP), and demographic questions.

RESULTS

Cognitive debriefing interviews demonstrated U-FIS acceptability. Analysis of postal survey data showed all new language versions to be unidimensional. Reliability was high, with test-retest correlations and internal-consistency coefficients exceeding 0.85. Initial evidence of validity was provided by moderate to high correlations with NHP scales. The U-FIS was able to discriminate between groups based on employment status, perceived MS severity, and general health.

CONCLUSION

The U-FIS is a practical new measure of the impact of fatigue. It was successfully adapted into eight new languages to broaden availability for researchers. Psychometric analyses indicated that the new language versions were unidimensional and reproducible with promising construct validity.

MS, exercise, and the potential for older adults

Multiple Sclerosis (MS) is an autoimmune disorder of the central nervous system. The average onset of the disease is 30 years of age, and it afflicts women more often than men (ratio of approximately 2:1). The symptoms of the disease include fatigue, motor weakness, heat sensitivity, reduced mobility, abnormal gait mechanics, and poor balance. These symptoms decrease cognitive and physical functional capacity of an individual and tend to result in sedentary lifestyle behaviors. A sedentary lifestyle among individuals with MS increases the risk of secondary diseases such as coronary heart disease and obesity, particularly as one ages. The effect of exercise in treating symptoms of MS has been under explored, perhaps due to the fact that exercise was thought to magnify MS-related fatigue and other symptoms. Recent research has challenged this notion, advocating exercise as an effective therapy for the management of MS, as well as maintaining overall fitness and improving quality-of-life measures. While the research shows clear benefits, the barriers to exercise participation among MS patients are significant. Recommendations for various forms of exercise are provided, along with strategies for overcoming barriers to participation.

MRI of the corpus callosum in multiple sclerosis: association with disability

Inflammatory demyelination and axon damage in the corpus callosum are prominent features of multiple sclerosis (MS) and may partially account for impaired performance on complex tasks. The objective of this article was to characterize quantitative callosal MRI abnormalities and their association with disability. In 69 participants with MS and 29 healthy volunteers, lesional and extralesional callosal MRI indices were estimated via diffusion tensor tractography. expanded disability status scale (EDSS) and MS functional composite (MSFC) scores were recorded in 53 of the participants with MS. All tested callosal MRI indices were diffusely abnormal in MS. EDSS score was correlated only with age (r = 0.51). Scores on the overall MSFC and its paced serial auditory addition test (PASAT) and 9-hole peg test components were correlated with callosal fractional anisotropy (r = 0.27, 0.35, and 0.31, respectively) and perpendicular diffusivity (r = -0.29, -0.30, and -0.31) but not with overall callosal volume or callosal lesion volume; the PASAT score was more weakly correlated with callosal magnetization-transfer ratio (r = 0.21). Anterior callosal abnormalities were associated with impaired PASAT performance and posterior abnormalities with slow performance on the 9-hole peg test. In conclusion, abnormalities in the corpus callosum can be assessed with quantitative MRI and are associated with cognitive and complex upper-extremity dysfunction in MS.

A randomized trial of memantine as treatment for spasticity in multiple sclerosis

We report the results of a single center randomized, double-blind, placebo-controlled, parallel group trial of memantine in adults with multiple sclerosis and spasticity conducted over 12 weeks. Eligible MS patients had to have an Ashworth spasticity rating of 2 or higher in at least one lower extremity muscle group. Subjects were randomized to receive either placebo or memantine 10 mg twice a day. The primary outcome measure for efficacy was the change in Ashworth Spasticity Scale Score. Although well tolerated, memantine treatment did not demonstrate efficacy in treatment of spasticity in this 12-week small exploratory study.

Quantitative estimation of muscle fatigue using surface electromyography during static muscle contraction

Muscle fatigue is commonly associated with the musculoskeletal disorder problem. Previously, various techniques were proposed to index the muscle fatigue from electromyography signal. However, quantitative measurement is still difficult to achieve. This study aimed at proposing a method to estimate the degree of muscle fatigue quantitatively. A fatigue model was first constructed using handgrip dynamometer by conducting a series of static contraction tasks. Then the degree muscle fatigue can be estimated from electromyography signal with reasonable accuracy. The error of the estimated muscle fatigue was less than 10% MVC and no significant difference was found between the estimated value and the one measured using force sensor. Although the results were promising, there were still some limitations that need to be overcome in future study.

Single-Dose pharmacokinetics of sustained-release fampridine (Fampridine-SR) in healthy volunteers and adults with renal impairment

Fampridine-SR is a sustained-release formulation of fampridine (4-aminopyridine), a potassium channel blocker demonstrated to improve walking ability in patients with multiple sclerosis. This study evaluated the pharmacokinetics of fampridine and its metabolites after administration of fampridine-SR 10 mg in healthy volunteers and in subjects with mild, moderate, or severe renal impairment (5 per group). Analysis of variance was used to calculate 90% confidence intervals (CIs) for the ratios (impaired/healthy) of least squares mean in maximum plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC). Clearance was primarily through urinary excretion. In renally impaired subjects, fampridine plasma concentrations were consistently higher than in healthy individuals: ratios for C(max) ranged from 166.5% to 199.9% for mild and severe renal impairment, respectively. AUC(0-infinity) ratios ranged from 175.3% to 398.7%, respectively, for mild and severe renal impairment. Mean terminal disposition half-life was 6.4 hours in healthy individuals, compared with 7.4, 8.1, and 14.3 hours in patients with mild, moderate, and severe renal impairment, respectively. Regression analysis confirmed the significant relationship between creatinine clearance and extent of exposure as quantified by AUC for fampridine and its metabolites, suggesting cautious use in patients with mild renal impairment and avoidance in cases of moderate or severe renal impairment.

Quantitative assessment of motor fatigue: Normative values and comparison with prior‐polio patients

Motor fatigue is a common complaint of polio survivors and has a negative impact on activities of daily living. The aim of this study was to establish a normative database for hand grip strength and fatigue and to investigate differences between prior-polio subjects and normal controls. Static and dynamic hand grip fatigue and maximum voluntary isometric contraction (MVIC) of hand grip were measured in subjects with a prior history of polio (n = 44) and healthy controls (n = 494). A normative database of fatigue was developed using four indices of analysis. Compared with healthy controls, subjects with prior polio had significantly reduced hand grip strength but developed greater hand grip fatigue in only one fatigue index. Quantitative measurement of fatigue in the prior-polio population may be useful in order to detect change over time and to evaluate treatment strategies.

Contributors to fatigue resistance of the hamstrings and quadriceps in cerebral palsy

BACKGROUND

The purpose of this study was to elucidate relationships between quadriceps and hamstrings voluntary muscle fatigue and upper motor lesion impairments in cerebral palsy in order to gain a better understanding of their contribution to the observed fatigue resistance.

METHODS

Seventeen ambulatory subjects with cerebral palsy (mean age: 17.0, SD=4.8 years) were recruited. Quantitative measures of strength, spasticity, cocontraction, and stiffness for both muscle groups were collected on an isokinetic dynamometer and entered in a factor analysis. The resulting factors were used as independent variables in a multiple regression analysis with quadriceps and hamstrings fatigue as dependent variables.

FINDINGS

Five independent factors explained 90% of the variance. In order of loadings, higher hamstring cocontraction and spasticity and lower hamstring strength were associated with lower levels of hamstring fatigue. Higher quadriceps cocontraction and lower quadriceps strength were the most predictive of lower levels of quadriceps fatigue.

INTERPRETATION

Greater motor impairments of the agonist muscle, particularly cocontraction, spasticity, and weakness, were associated with lower rates of muscle fatigue of the same muscle during performance of a voluntary fatigue protocol for the hamstrings and quadriceps. Muscles are highly adaptable; therefore, the results of this study suggest that the observed fatigue resistance may be due to the effect of the primary neural insult on motor unit recruitment and rate modulation or the result of secondary adaptations to spasticity, weakness, or excessive cocontraction.

Leg power asymmetry and postural control in women with multiple sclerosis

The extent of and the interactions between muscle strength, walking speed, postural control, and symptomatic fatigue in multiple sclerosis (MS) are not known, nor are the effects of bilateral strength asymmetries on these variables.

PURPOSE

To quantify the magnitude of and the associations between bilateral strength and limb-loading asymmetries, postural control, and symptomatic fatigue in women with MS.

METHODS

Peak knee extensor (KE) and dorsiflexor (DF) isometric torque and isotonic power were assessed bilaterally in 12 women with MS (Expanded Disability Status Scale = 4 +/- 1) and 12 age-matched female controls using a Biodex dynamometer (Biodex Medical, Shirley, NY). Center of pressure (CoP) variability during 20 s of quiet stance was measured in the anteroposterior (AP) and the mediolateral (ML) directions using adjacent force plates. Bilateral asymmetry scores were calculated for power and torque. Normal and brisk walk times (25 ft) and symptomatic fatigue (Visual Analog Fatigue Scale and Fatigue Severity Scale) were measured before strength and balance testing.

RESULTS

Fatigue was greater and walk times (normal and brisk) were longer in MS (P < or = 0.01). Dorsiflexor (DF) isometric torque and power and knee extensor (KE) isometric strength were similar between groups. KE power was lower (mean +/- SD = 21.5 +/- 16.2%; P < or = 0.05) and KE power asymmetry was greater in MS than in controls (9.2 +/- 6.9%; P = 0.02). Postural variability of the CoP was greater in the AP direction in MS than in controls (7.52 +/- 3.02 and 4.33 +/- 1.79 mm, respectively; P = 0.005). KE power asymmetry was associated with fatigue and walk times (P < or = 0.02), and AP CoP variability was correlated with fatigue, walk times, and power asymmetries (P < or = 0.05).

CONCLUSIONS

These data provide new evidence of a potential role for KE strength asymmetries in the symptomatic fatigue and physical dysfunction of persons with MS, possibly through an effect on postural stability.

Fatigue versus activity-dependent fatigability in patients with central or peripheral motor impairments

In the rehabilitation literature, fatigue is a common symptom of patients with any neurological impairment when defined as a subjective lack of physical and mental energy that interferes with usual activities. Some complaints may, however, arise from fatigability , an objective decline in strength as routine use of muscle groups proceeds. By this refined definition of fatigue, exercise or sustained use reduces the ability of muscles to produce force or power, regardless of whether the task can be sustained. Fatigability may be masked clinically because (1) the degree of weakening is not profound, (2) activity-induced weakness rapidly lessens with cessation of exertion, and (3) clinicians rarely test for changes in strength after repetitive movements to objectively entertain the diagnosis. The repetitive movements that induce fatigability during daily activities are an iterative physiological process that depends on changing states induced by activation of spared central and peripheral neurons and axons and compromised muscle. Fatigability may be especially difficult to localize in patients undergoing neurorehabilitation, in part because no finite boundary exists between the central and peripheral components of motor reserve and endurance. At the bedside, however, manual muscle testing before and after repetitive movements could at least put some focus on the presence of fatigability in any patient with motor impairments and related disabilities. Reliable measures of fatigability beyond a careful clinical examination, such as physiological changes monitored by cerebral functional neuroimaging techniques and more standardized central and peripheral electrical and magnetic stimulation paradigms, may help determine the mechanisms of activity-dependent weakening and lead to specific therapies. Testable interventions to increase motor reserve include muscle strengthening and endurance exercises, varying the biomechanical requirements of repetitive muscle contractions, and training-induced neural plasticity or pharmacologic manipulations to enhance synaptic efficacy.

Exercise and brain health--implications for multiple sclerosis: Part II--immune factors and stress hormones

Part I of this review addressed the possible modulatory role of exercise on neuronal growth factors to promote brain health in neurodegenerative diseases such as multiple sclerosis (MS), which is characterized by varied patterns of inflammation, demyelination and axonal loss. Part II presents evidence that supports the potential neuroprotective effect of exercise on the modulation of immune factors and stress hormones in MS. Many current therapies used to attenuate MS progression are mediated, at least in part, through alterations in the relative concentrations of pro- and anti-inflammatory cytokines. Exercise-induced alterations in local and systemic cytokine production may also benefit immune function in health and disease. Exercise immunomodulation appears to be mediated by a complex interaction of hormones, cytokines and neural factors that may favorably influence immune variables in MS. The promising interplay between exercise and brain health in MS deserves further investigation.

Evaluation of the six-minute walk in multiple sclerosis subjects and healthy controls

Objective To assess the characteristics of the 6-min walk (6MW) in multiple sclerosis (MS) subjects of varied disability, and controls. To assess the correlation of 6MW to subjective measures of fatigue, health status and ambulation using the modified fatigue impact scale (MFIS), short form-36 Health Questionnaire physical component score and MS walking scale (MSWS).

Methods Forty MS expanded disability status scale [(EDSS) 0—6.5] and 20 control subjects were recruited from a MS outpatient clinic. Subjects completed survey material and three 6MWs with 1-h interval rest in a single study visit.

Results There was no practice effect or fatigability with repeat 6MW tests with a one-h rest period between test sessions. The 6MW had excellent intra-[intraclass correlation coefficient (ICC) = 0.95] and inter-rater (ICC = 0.91) reliability. MS subjects demonstrated reduced 6MW distance and speed compared with controls ( P < 0.0001). Within the MS population 6MW distance was significantly reduced with increasing disability ( P = 0.05). Compared with the EDSS, the 6MW had a stronger correlation to subjective measures of ambulation and physical fatigue: MSWS ( r = -0.81 versus 0.69) and MFISphy (0.66 versus 0.63).

Conclusions The 6MW is a feasible, reproducible, and reliable measure in MS. MS subjects demonstrate motor fatigue in both 6MW distance and speed compared with controls. In MS subjects there is an inverse relationship between motor fatigue and disability. 6MW has a strong correlation to subjective measures of ambulation and physical fatigue. Multiple Sclerosis 2008; 14: 383—390. http://msj.sagepub.com

Qualitative and quantitative assessment of fatigue in multiple sclerosis (MS)

It was the aim of the present study to develop a synoptic multidimensional test system for assessment of fatigue in multiple sclerosis (MS) patients objectifying physical and mental fatigue as well as the subjective and objective standpoint in these two fatigue forms. Seventy nine patients with relapsing remitting multiple sclerosis (RRMS) and 51 age-matched healthy controls (H) were analysed by means of the physical fatigue test (hand dynamometer) and an objective mental fatigue test (vigilance test from the computerised Test Battery for Attentional Performance). Furthermore, subjective tiredness caused by test procedures, subjective persisting tiredness (Modified Fatigue Impact Scale; MFIS: physical and cognitive scale) and mood (Beck Depression Inventory; BDI-18) were analysed.MS patients differed significantly from the controls in their objective physical and mental performance under fatigue, as well as in their subjective estimation of tiredness. MS patients showed an inverse relationship between below-average objective performance and high subjective feeling of tiredness when compared to controls. Subjectively severely tired MS patients achieved clearly poorer performances on the hand dynamometer test and slightly poorer performances on the vigilance test when compared to subjectively rarely tired MS patients. Depressed MS patients estimated their subjective tiredness in the MFIS significantly higher than non-depressed MS patients, but attained the same objective performance. This set of standardised tests enables meaningful comparisons between objective fatigue performance and subjective fatigue estimations in the physical and mental sphere and considers the influence of depression. Depression affects the subjective tiredness but not the objective fatigue performance.

Multiple sclerosis and physical exercise: recommendations for the application of resistance-, endurance- and combined training

This review summarizes the existing knowledge regarding the effects of physical exercise in patients suffering from multiple sclerosis (MS). Furthermore, recommendations are given regarding exercise prescription for MS patients and for future study directions. Previously, MS patients were advised not to participate in physical exercise. During recent years, it has been increasingly acknowledged that exercise benefits MS patients. The requirement for exercise in MS patients is emphasized by their physiological profile, which probably reflects both the effects of the disease per se and the reversible effects of an inactive lifestyle. To date the effects of exercise have only been studied in moderately impaired MS patients with an EDSS score of less than 7. Evidence exists for recommending participation in endurance training at low to moderate intensity, as the existing literature demonstrates that MS patients can both tolerate and benefit from this training modality. Also, resistance training of moderate intensity seems to be well tolerated and to have beneficial effects on MS patients, but the methodological quality of the existing evidence is in general low and the number of studies is limited. Only two studies have evaluated the effects of combined resistance- and endurance training, making solid conclusions regarding this training modality impossible.

Fatigue in neuroimmunological diseases

Fatigue is a widespread symptom in numerous neuroimmunological diseases like multiple sclerosis (MS), myasthenia gravis, morbus Behcet, neurosarcoidosis, neuroborreliosis or immune vasculitis. This phenomenon is best investigated in MS. The complex mechanisms underlying fatigue in MS are still poorly understood; alterations in immune system activation, central nervous system dysregulation, impaired nerve conduction, and neuroendocrine dysregulation have to be considered. These immune and neural mechanisms may cause the initial symptoms of fatigue; however, the fatigue symptom may be exacerbated by secondary overlapping factors (e. g. depressive mood, sleep disturbances, unhealthy life style) which are likely associated with the feeling of fatigue. Wessely conceptualised four components of fatigue: behaviour (effects of fatigue), feeling (subjective experience), mechanisms, and context (e. g. environment, attitudes). So far most examinations have dealt with the first or the second component of the multidimensional construct fatigue, either concentrating on the behavioural aspect in the physical or in the cognitive sphere or on the subjective aspect. The Rostock Fatigue Study investigated two of the components: objective performance and subjective fatigue estimation in the cognitive and in the physical sphere. MS patients showed a reversed relationship between below-average objective performance in the cognitive and in the physical sphere and high subjective feeling of tiredness when compared to healthy individuals. The clinical management of fatigue should include an assessment of the various factors that can cause fatigue as well as a step-wise treatment approach that encompasses nonpharmacological approaches and pharmacological interventions.

P300 and treatment effect of modafinil on fatigue in multiple sclerosis

To evaluate the value of visual and auditory P300 for predicting the response of multiple sclerosis-related fatigue to modafinil treatment, 33 patients were treated with 100 mg modafinil once daily for 4 weeks, following a 4-week baseline phase and an optional 8-week extension phase. The main clinical outcome parameter was a decrease in the fatigue visual analogue score (VAS) before and after 4 weeks of treatment. Patients with shorter auditory P300 latency at baseline were more likely to benefit from modafinil treatment. Auditory P300 latency predicted treatment response with a specificity of 76% and a sensitivity of 75% at a cut-off latency of 350 ms. Visual P300 latency could not be used to predict treatment response. Baseline auditory P300 latency predicted treatment response, whereas visual P300 latency did not. Clinical improvement did not correlate with changes in either visual or auditory P300.

The validity and reliability of the Fatigue Severity Scale in Turkish multiple sclerosis patients

The aims of this study were to investigate the Fatigue Severity Scale's Turkish version's validity, reproducibility, internal consistency and parameters. Multiple sclerosis patients' disability levels were determined by the Expended Disability Status Scale and depression status was established with the Beck Depression Inventory. The Fatigue Severity Scale and Beck Depression Inventory were administered through self-report methods and assistance, without guidance, given where needed. An interval of 1 week was allowed between the applications. Seventy-two definitely diagnosed multiple sclerosis patients and matched 76 healthy controls were included. The multiple sclerosis patients' median Expended Disability Status Scale score was 4.0 (1.0-9.5). There were statistically significant differences between multiple sclerosis patients' and healthy controls' Fatigue Severity Scale scores (P<0.001). After controlling for depression, Fatigue Severity Scale scores were lowered, but there was still a significant difference between them (P<0.001). There was no significant difference between the interviews for Fatigue Severity Scale1 and Fatigue Severity Scale2 (P=0.719). Internal consistency for Fatigue Severity Scale was good for multiple sclerosis patients (ICC=0.81, P<0.001). Cronbach's alpha of Fatigue Severity Scale1 was 0.89; Fatigue Severity Scale2 was 0.94. Expended Disability Status Scale scores (P<0.05) and Beck Depression Inventory scores (P<0.001) have a significant effect on the Fatigue Severity Scale. In conclusion, scales have a great importance in following up and assessing the results of treatment strategies. The Turkish validation of the Fatigue Severity Scale is reliable and valid, and is an appropriate tool to assess fatigue in the Turkish multiple sclerosis population.

Fampridine-SR in multiple sclerosis: a randomized, double-blind, placebo-controlled, dose-ranging study

Objective To determine the safety of sustained-release 4-aminopyridine in subjects with mutiple sclerosis (MS) and to examine dose-related efficacy up to 40 mg twice daily.

Method Multicenter, randomized, double-blind, placebo-controlled, study. Following a 4-week baseline peroid, subjects were randomly assigned to receive Fampridine-SR (n=25, doses from 10 to 40 mg twice daily, increasing in 5 mg increments weekly) or placebo (n=11). A battery of assessments was performed weekly, including the MS Functional Composite (MSFC), fatigue questionnaires, and lower extremity manual muscle testing.

Results The most common adverse events were dizziness, insomnia, paresthesia, asthenia, nausea, headache, and tremor. Five subjects were discontinued from Fampridine-SR because of adverse events at doses greater than 25 mg, and these included convulsions in two subjects at doses of 30 and 35 mg twice daily. Improvement were seen in lower extremity muscle strength (prospective analysis) and walking speed (post-hoc analysis) in the Fampridine-SR group compared to placebo (unadjusted p-values of 0.01 and 0.03, respectively). There were no significant differences in other MSFC measure or fatigue scores.

Conclusions Future studies should employ doses up to 20 mg twice daily with lower extremity strength and walking speed as potential outcome measures. Multiple Sclerosis 2007; 13: 357-368. http://msj.sagepub.com

Effects of exercise and creatine on myosin heavy chain isoform composition in patients with Charcot-Marie-Tooth disease

It is not known whether myosin heavy chain (MHC) content changes in response to exercise training or creatine supplementation in subjects with Charcot-Marie-Tooth disease (CMT). Based on previous data, we hypothesized that resistance exercise and creatine would increase the percentage of type I MHC composition in the vastus lateralis muscle and that myosin isoform changes would correlate with improved chair rise-time in CMT subjects. To test this hypothesis, 18 CMT subjects were randomly assigned to either a placebo or creatine group. All subjects performed a 12-week, home-based, moderate-intensity resistance training program. Chair rise-time was measured before and after the training program. Muscle biopsies were obtained from the vastus lateralis before and after the 12-week program. Gel electrophoresis showed a significant decrease (approximately 30%) in MHC type I in CMT subjects given creatine supplementation when compared with placebo. There was a nonsignificant increase in both MHC type IIa (approximately 23%) and MHC type IIx (approximately 7%) in CMT subjects given creatine. Reduced MHC type I content and increased MHC type IIa content correlated with faster chair rise-times (i.e., improved muscle performance). The training-induced change in MHC IIa content was inversely correlated with chair rise-time in CMT subjects given creatine. When the two subject groups were combined, there was a linear, negative relationship between the change in MHC type IIa content and chair rise-time after training and a positive relationship between the training-induced change in MHC type I content and chair rise-time. These data suggest that improved function (chair rise-time) was associated with a lower level of MHC type I and increased MHC type IIa composition. Furthermore, the data are consistent with the hypothesis that creatine supplementation alters MHC composition in CMT patients undergoing resistance training and that MHC changes associated with creatine supplementation can improve muscle function.

A rapid screening tool for fatigue impact in multiple sclerosis

BACKGROUND

Fatigue is a common complaint in multiple sclerosis (MS) and often interferes with daily functioning. Both clinicians and researchers may need to detect high levels of fatigue impact using a time and effort efficient tool. This study evaluates the psychometric properties of a rapid screening instrument for fatigue impact in multiple sclerosis.

METHODS

Three visual analogue scales (VAS) for assessing the impact of fatigue were developed. Sixty two subjects with definite MS (mean age 52 +/- 10.5 years; 29 women) and 24 healthy controls (mean age 52 +/- 14 years; 13 women) completed all VAS scales (range 0-100), the Fatigue Severity Scale (FSS) (range 7-63), the Modified Fatigue Impact Scale (MFIS) (range 0-84) and the Guy's Neurological Disability Scale (GNDS) (range 0-5). All tests were repeated with an interval of maximum three days. To evaluate the reproducibility, intraclass correlations (ICC) were calculated, based on one-way analysis of variance for repeated measurements. Validity was considered by means of correlation coefficients. ROC analysis was used to determine the accuracy of the VAS scales.

RESULTS

The ICC of the VAS scales ranged from 0.68 to 0.69. VAS scales showed low to moderate correlation with FSS, MFIS and GNDS (Kendall's tau 0.23-0.45) and were not related with physical or cognitive performance, or with depression. All VAS scales were able to discriminate between subjects with MS and controls. Twenty five subjects with MS had a Fatigue Severity Scale score of 36 or more and were classified into the "fatigue" group. ROC analysis showed that VAS_1 is most useful to classify subjects in the "fatigue" group. A cut-off value of VAS_1 of 59 displayed 76% sensitivity and 72% specificity. When using the MFIS score of 40 or more to classify the groups, VAS_1 remained the strongest tool, with 81% sensitivity and 77% specificity at a cut-off value of 59.

CONCLUSION

The VAS for the impact of fatigue on daily life (VAS_1) is a moderately reliable, though valid and useful tool to screen rapidly for fatigue impact in multiple sclerosis. A cut-off value of 59 satisfactorily classifies individuals having severe fatigue with a high impact on daily life. In clinical practice, a more comprehensive assessment of fatigue and the impact on daily life is recommended.

[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.

Reliability of physical functioning measures in ambulatory subjects with MS

BACKGROUND AND PURPOSE

One of the primary reasons for measuring outcomes during rehabilitation is to determine the effect of physiotherapy. Repeated measurement situations are susceptible to several sources of error, including inconsistencies caused by the subject, the procedure, the instrument and the examiner. Therefore, the reliability of the measures needs to be examined.

METHOD

The present study used a repeated-measures design. Two studies were undertaken to examine the test-retest and inter-rater reliability for physical functioning measures. The interval between the measurements was one week. The sample consisted of 19 ambulatory subjects with multiple sclerosis (MS) in the test-retest and nine subjects in the inter-rater reliability study. The measures were selected to assess different domains of the World Health Organization International Classification of Functioning, Disability and Health (WHO, 2001). Several parameters of the Box and Block Test (BBT), the Berg Balance Scale (BBS), the Kela Coordination test, the postural stability test, the timed 10-metre gait test, the six-minute walk test, the shoulder tug test, grip strength, maximal isometric force of the knee extensors, muscle endurance tests, the modified Ashworth Scale and passive straight leg raise test were examined in terms of reliability.

RESULTS

The intra-class coefficient (ICC) values for test-retest reliability were >0.80 in 17 of 23 parameters, and correspondingly so in 20 out of 26 parameters for inter-rater reliability. Poor reliability (defined as ICC < or = 0. 60) was obtained only for the patient classification index (PCI) of the six-minute walk test in the test-retest reliability study. In general, the coefficient of variation was good. A moderate amount of variability was discovered for the Kela Coordination test, and for postural stability and muscle endurance tests. The data obtained from the modified Ashworth Scale and the shoulder tug test were highly skewed and the percentage of agreement ranged between 63.9% and 93.4%.

CONCLUSIONS

The study revealed acceptable test-retest and inter-rater reliability of these measures in ambulatory subjects with MS, with the exception of the Modified Ashworth Scale and the shoulder tug test.

Exercise and Rehabilitation for Individuals with Multiple Sclerosis

It is the coexistence of physical and cognitive impairments, together with emotional and social issues in a disease with an uncertain course, that makes MS rehabilitation unique and challenging. Inpatient rehabilitation improves functional independence but has only limited success improving the level of neurologic impairment. Benefits are usually not long lasting. Severely disabled people derive equal or more benefit than those who are less disabled, but cognitive problems and ataxia tend to be refractory. There is now good evidence that exercise can improve fitness and function for those with mild MS and helps to maintain function for those with moderate to severe disability. Therapy can be performed over 6 to 15 weeks in outpatient or home-based settings or as a weekly day program lasting several months. Several different forms of exercise have been investigated. For most individuals, aerobic exercise that incorporates a degree of balance training and socialization is recommended. Time constraints, access, impairment level, personal preferences, motivations, and funding sources influence the prescription for exercise and other components of rehabilitation. Just as immunomodulatory drugs must be taken on a continual basis and be adjusted as the disease progresses, so should rehabilitation be viewed as an ongoing process to maintain and restore maximum function and QOL.

Assessment of muscle strength and motor fatigue with a knee dynamometer in subjects with multiple sclerosis: a new fatigue index

OBJECTIVE

To measure muscle strength and motor fatigue with a knee dynamometer and to assess the intra-rater reliability of measurements for maximal isometric extensor and flexor torques and the reliability of a new fatigue index (FI) in patients with mild to moderate multiple sclerosis (MS).

DESIGN

Repeated assessments with one-week intervals.

SETTING

The Masku Neurological Rehabilitation Centre, Masku, and the Social Insurance Institution, Research Department, Turku, Finland.

SUBJECTS

Twenty-eight MS patients.

OUTCOME MEASURES

Maximal isometric torque during 5 s and fatigue of knee flexors and extensors during isometric contractions of 30 s were assessed. A new FI was established and compared with the two previously used indices (FI1 and FI2). All three indices are based on the calculated area under the force versus time curve (AUFC), with FI1 using the 30-s recording time in its entirety and F2 omitting the initial 5 s in the calculation. In the new fatigue index (FI3), the time point of maximum (TPM) torque achieved by the subject is used as the starting point in the calculation. The patient's subjective fatigue was measured by Fatigue Severity Scale (FSS).

RESULTS

The intraclass correlation coefficient (ICC) was 0.97 in maximal isometric torque measurements. FI3 showed good intra-rater reliability (ICC =0.68-0.86). None of the fatigue indices correlated with FSS.

CONCLUSIONS

Maximal isometric torque and motor fatigue of knee flexor and extensor muscles can be reliably measured using a knee dynamometer in MS patients. The new FI proved to be a reliable model for MS patients.

Resistance training effectiveness in patients with Charcot-Marie-Tooth disease: recommendations for exercise prescription

OBJECTIVES

To determine the effects of a 12-week, home-based resistance exercise program on strength, body composition, and activities of daily living (ADLs) in men and women with Charcot-Marie-Tooth (CMT) disease and to design an ADL-based resistance exercise prescription template.

DESIGN

Double-blind, placebo-controlled study.

SETTING

Testing in a university setting; exercise in patients' homes.

PARTICIPANTS

Twenty CMT patients who volunteered.

INTERVENTION

Subjects progressively strength trained at home 3 d/wk for 12 weeks.

MAIN OUTCOME MEASURES

Timed ADLs, isometric strength, and body composition.

RESULTS

Absolute strength was greater in men with CMT in only 4 of 10 baseline measures (P<.05), but not when strength was normalized by lean mass. Training compliance was 87% with no gender differences. At baseline, women had 80% of normal strength in 4 of 10 measures, whereas men did not achieve 80% of normal strength in any measure. After training, women had 80% of normal strength in 8 of 10 measures, whereas men only had 80% of normal strength in 1. Training volumes and strength change scores showed no gender differences. ADLs improved after training with no gender differences (P<.05). An exercise prescription template was developed by using chair-rise time to estimate starting weights for lower body and supine rise for upper body.

CONCLUSIONS

Resistance training improved strength and ADLs equally in men and women. We designed an exercise prescription recommendation, based on ADL performance.

Resistance training exercise and creatine in patients with Charcot-Marie-Tooth disease

Resistance exercise and creatine supplementation independently improve strength and function in patients with certain neuromuscular diseases. The purpose of this study was to examine the effects of resistance training with and without creatine supplementation on muscle, strength, and function in patients with Charcot-Marie-Tooth (CMT) disease. Twenty patients with CMT consumed 5 g/day creatine or placebo while participating in resistance training for 12 weeks. Energy metabolites, muscle fiber type and size, strength, and timed activities of daily living were measured before and after training. There were no differences between creatine or placebo groups for any outcome. For the groups combined, exercise training increased type I muscle fiber diameter (48.2 +/- 14.2 microm vs. 55.4 +/- 14.8 microm), strength, and activities of daily living (ADL) times. Thus, patients respond to resistance training with muscle fiber adaptations, and improvements in strength and function. Creatine was not beneficial.

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.

Veränderung der Muskelkraft bei Patientinnen mit Anorexia nervosa während der stationären Behandlung - eine Pilotstudie

Zusammenfassung: Fragestellung: Die Veränderung der Muskelkraft bei Patientinnen mit Anorexia nervosa während der stationären Behandlung sollte durch exakte Messung bestimmt werden. Methode: Unter Verwendung einer etablierten Messvorrichtung inkl. des Softwareprogramms «Quantitative Muscle Assessment» wurden in den Wochen 1, 2, 3, 4, 6, 8 und 10 des stationären Aufenthaltes die Maximalkräfte in vier verschiedenen Übungen für jede Körperseite bei zehn Patientinnen bestimmt. Alle wiesen vor der stationären Aufnahme einen vergleichbaren Krankheitsverlauf mit reiner Nahrungsrestriktion ohne überdurchschnittliche sportliche Betätigung auf. Ergebnisse: Es ergaben sich Hinweise auf einen interindividuell zu beobachtenden mehrphasigen Verlauf der Kraftrestitution. Die aufgrund der einfachen Durchführung andernorts häufig angewandte Übung Handgrip zeigte im Gegensatz zu den anderen untersuchten Muskelgruppen keine einheitliche Entwicklung. Seitendifferenzen waren nicht zu beobachten. Schlussfolgerungen: Patientinnen mit Anorexia nervosa zeigen eine objektivierbare, interindividuell vergleichbare, mehrphasige Zunahme der Maximalkraft der untersuchten Muskelgruppen während der Gewichtsrestitution.

Measuring fatigue in people with multiple sclerosis

OBJECTIVE

To compare methods of assessing fatigue.

DESIGN

Cross sectional.

SETTING

Community.

SUBJECTS

Forty Multile Sclerosis (MS) patients and 20 healthy controls.

MAIN OUTCOME MEASURES

Fatigue questionnaires, SDSA dot cancellation test, finger tapping test, TEA Lottery.

RESULTS

The MS patients had significantly higher levels of fatigue than the controls on the Task Induced Fatigue Scale, Fatigue Severity Scale and Fatigue Impact Scale. The Task Induced Fatigue Scale completed whilst imagining oneself driving and the Fatigue Assessment Instrument did not differentiate between MS patients and controls. Finger tapping differentiated between MS patients and controls but there was no significant difference between MS patients and controls on visual and auditory concentration tests. A factor analysis indicated that questionnaire measures of fatigue were interrelated but independent of objective test performance.

CONCLUSIONS

Questionnaire measures can be used to assess fatigue in people with MS. The FSS differentiated MS patients from controls and is relatively short. It was therefore recommended for clinical use.

Fatigue associated with multiple sclerosis: diagnosis, impact and management

In patients with multiple sclerosis (MS) fatigue is the most common symptom and one of the most disabling features. As many as 40% have described it as the single most disabling symptom--a higher percentage than weakness, spasticity, motor problems, or bowel or bladder problems. The etiology and pathophysiology of MS-related fatigue remain unknown. Studies have failed to demonstrate an association between MS-related fatigue and the level of disability, clinical disease subtype, or gender, although recent data show an association between MS-related fatigue and depression and quality of life. Imaging studies using positron emission tomography suggest that fatigue in MS is related to hypometabolism of specific brain areas, including the frontal and subcortical circuits. The impact of fatigue on patient functioning and quality of life clearly warrants intervention. In addition to nonpharmacologic measures, such as exercise and energy conservation strategies, several pharmacologic agents have been evaluated for their ability to reduce MS-related fatigue, including amantadine, central nervous system stimulants (pemoline), and the novel wake-promoting agent modafinil.

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.

Hand strength and fatigue in patients with hereditary motor and sensory neuropathy (types I and II)

OBJECTIVES

To compare maximal isometric hand strength and fatigue between subjects with hereditary motor and sensory neuropathy (HMSN) and healthy controls and to test the reproducibility of handgrip strength (peak force of handgrip [PFgrip]) and fatigue.

DESIGN

PFgrip and the decline in PFgrip during 3 sets of 15 contractions were compared.

SETTING

University hospital in The Netherlands.

PARTICIPANTS

Twenty subjects with HMSN and 20 age- and sex-matched healthy controls; 15 healthy subjects for the reproducibility part of the study.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

PFgrip and the decline in PFgrip were compared by using a digital handgrip dynamometer. Two-point and lateral pinch measurements of subjects with HMSN were standardized against reference values. Reproducibility measurements were performed on 15 healthy subjects on 2 separate occasions within a 1-week interval.

RESULTS

PFgrip was significantly lower in the HMSN subjects compared with controls (P<.05). Pinch measurements also showed a large variance from average normal performance. No significant difference was found in the decline in percentage of PFgrip. Reproducibility was excellent for PFgrip (intraclass correlation coefficient [ICC]=.98; 95% confidence interval [CI],.95-.99) but poor for fatigue (ICC=.62; 95% CI,.20-.85).

CONCLUSION

PFgrip and 2-point and lateral pinch in HMSN subjects were significantly reduced compared with healthy controls. Our findings indicated that the rate of decline of PFgrip during effort does not vary between groups.

Is there a differential impact of fatigue and physical disability on quality of life in multiple sclerosis?

To investigate the quantitative impact of fatigue on health-related quality of life (HRQoL) in multiple sclerosis (MS) and to determine whether fatigue was related to HRQoL independently from bodily disability, data on HRQoL were ascertained for 87 patients with definite MS by using the SF-36. HRQoL scores and subscores were related to the basic MS disability score (EDSS) and further MS parameters, and to fatigue, which was assessed by using different fatigue scales. Factors related to predominantly physical but not mental HRQoL aspects were identified as related to EDSS, duration of disease, and age. Different fatigue scores did impact significantly on both physical and especially mental HRQoL. The influence of fatigue on physical HRQoL was independent from EDSS. Fatigue experience reduces HRQoL markedly and independently from EDSS. Therefore, fatigue assessment provides additional information to disability-derived scales such as the EDSS with relevant implications for therapeutic decisions.

Quantitative assessment of motor fatigue in amyotrophic lateral sclerosis

Motor fatigue is a common complaint in patients with amyotrophic lateral sclerosis (ALS), but is often excluded, unlike weakness, from the clinical assessment of these patients. This could be due to the complexity and often painful assessment techniques of this motor deficit. This study examines the feasibility of quantitative assessment of motor fatigue by modifying presently available force measurements. The relationship between weakness and fatigue in ALS patients was also examined. Fifty-four ALS patients and 39 normal control subjects performed 30 s of sustained maximal voluntary isometric contraction (MVIC) of elbow flexors (EF), knee extensors (NE), and ankle dorsiflexors (DF), using a computerized force measurement system and standardized testing procedures. Fatigue index (FI) was digitally calculated, from the force-time curve, as the percentage of MVIC unable to be sustained over the 30-s period. Fatigue was greater in ALS patients than in normal control (mean=23% vs. 15%) in all muscles including muscles that were not clearly weak. Weakness and fatigue were poorly correlated in ALS patients and may be independent measures of the pathogeneses of ALS.