Walking capacities in multiple sclerosis measured by global positioning system odometer

Transparent Quality Optimization for Machine Learning-Based Regression in Neurology

The clinical monitoring of walking generates enormous amounts of data that contain extremely valuable information. Therefore, machine learning (ML) has rapidly entered the research arena to analyze and make predictions from large heterogeneous datasets. Such data-driven ML-based applications for various domains become increasingly applicable, and thus their software qualities are taken into focus. This work provides a proof of concept for applying state-of-the-art ML technology to predict the distance travelled of the 2-min walk test, an important neurological measurement which is an indicator of walking endurance. A transparent lean approach was emphasized to optimize the results in an explainable way and simultaneously meet the specified software requirements for a generic approach. It is a general-purpose strategy as a fractional−factorial design benchmark combined with standardized quality metrics based on a minimal technology build and a resulting optimized software prototype. Based on 400 training and 100 validation data, the achieved prediction yielded a relative error of 6.1% distributed over multiple experiments with an optimized configuration. The Adadelta algorithm (LR=0.000814, fModelSpread=5, nModelDepth=6, nepoch=1000) performed as the best model, with 90% of the predictions with an absolute error of <15 m. Factors such as gender, age, disease duration, or use of walking aids showed no effect on the relative error. For multiple sclerosis patients with high walking impairment (EDSS Ambulation Score ≥6), the relative difference was significant (n=30; 24.0%; p<0.050). The results show that it is possible to create a transparently working ML prototype for a given medical use case while meeting certain software qualities.

Automated Analysis of the Two-Minute Walk Test in Clinical Practice Using Accelerometer Data

One of the core problems for people with multiple sclerosis (pwMS) is the impairment of their ability to walk, which can be severely restrictive in everyday life. Therefore, monitoring of ambulatory function is of great importance to be able to effectively counteract disease progression. An extensive gait analysis, such as the Dresden protocol for multidimensional walking assessment, covers several facets of walking impairment including a 2-min walk test, in which the distance taken by the patient in two minutes is measured by an odometer. Using this approach, it is questionable how precise the measuring methods are at recording the distance traveled. In this project, we investigate whether the current measurement can be replaced by a digital measurement method based on accelerometers (six Opal sensors from the Mobility Lab system) that are attached to the patient’s body. We developed two algorithms using these data and compared the validity of these approaches using the results from 2-min walk tests from 562 pwMS that were collected with a gold-standard odometer. In 48.4% of pwMS, we detected an average relative measurement error of less than 5%, while results from 25.8% of the pwMS showed a relative measurement error of up to 10%. The algorithm had difficulties correctly calculating the walking distances in another 25.8% of pwMS; these results showed a measurement error of more than 20%. A main reason for this moderate performance was the variety of pathologically altered gait patterns in pwMS that may complicate the step detection. Overall, both algorithms achieved favorable levels of agreement (r = 0.884 and r = 0.980) with the odometer. Finally, we present suggestions for improvement of the measurement system to be implemented in the future.

Measuring Outdoor Walking Capacities Using Global Positioning System in People with Multiple Sclerosis: Clinical and Methodological Insights from an Exploratory Study

We aimed at showing how Global Positioning System (GPS) along with a previously validated speed processing methodology could be used to measure outdoor walking capacities in people with multiple sclerosis (MS). We also deal with methodological issues that may occur when conducting such measurements, and explore to what extent GPS-measured outdoor walking capacities (maximal walking distance [MWD_GPS] and usual walking speed) could be related to traditional functional outcomes (6-min total walking distance) in people with MS. Eighteen people with MS, with an Expanded Disability Status Scale score ≤6, completed a 6-min walking test and an outdoor walking session (60 min maximum) at usual pace during which participants were wearing a DG100 GPS receiver and could perform several walking bouts. Among the 12 participants with valid data (i.e., who correctly completed the outdoor session with no spurious GPS signals that could prevent the detection of the occurrence of a walking/stopping bout), the median (90% confidence interval, CI) outdoor walking speed was 2.52 km/h (2.17; 2.93). Ten participants (83% (56; 97)) had ≥1 stop during the session. Among these participants, the median of MWD_GPS was 410 m (226; 1350), and 40% (15; 70) did not reach their MWD_GPS during the first walking bout. Spearman correlations of MWD_GPS and walking speed with 6-min total walking distance were, respectively, 0.19 (-0.41; 0.95) and 0.66 (0.30; 1.00). Further work is required to provide guidance about GPS assessment in people with MS.

Outdoor Walking Test With a Global Positioning System Device as an Additional Tool for Functional Assessment of Older Women

The primary aim was to assess the test-retest reliability of an outdoor walking test with a global positioning system device in older women in a community setting. In addition, correlations between the suggested test and various tests recommended to evaluate muscle strength, walking speed, and self-perceived health status in older adults were studied. The study included 40 women aged 68 (SD = 5) years. The primary outcomes were total walked distance and mean walking speed. The secondary outcomes were lower-body strength, heart rate, speed in a 4-m walk test, and self-perceived health status. The intraclass correlation coefficients calculated for the total walked distance, mean walking speed, and mean heart rate were .94, .92, and .37, respectively. Thus, the suggested outdoor walking test with the application of a global positioning system device may be considered a reliable test tool, which can be recommended for the evaluation of walking ability among older women in a community setting.

Multiple Sclerosis and Clinical Gait Analysis before and after Fampridine: A Systematic Review

BACKGROUND

Gait impairment is one of the most disabling symptoms in people with multiple sclerosis (PwMS). Fampridine, has demonstrated a positive effect on gait speed in PwMS after 14 days of treatment but the long-term effects have not yet been demonstrated. This study reviews the long-term effects of fampridine on gait in PwMS.

SUMMARY

This systematic review was conducted according to the PRISMA statement. Studies were considered long term if treatment exceeded 28 days. From the 498 studies identified, 18 (2,200 patients) fulfilled all eligibility criteria. Only 3 studies followed-up patients for >1 year and one of these showed a non-significant improvement in the gait speed. Key Messages: Fampridine seems to be beneficial at improving gait speed in PwMS in the long term. Further long-term studies are needed on related gait and functional parameters.

Can global positioning systems quantify participation in cerebral palsy?

This study examined whether motor-related participation could be assessed by global positioning systems in individuals with cerebral palsy. Global positioning systems monitoring devices were given to 2 adolescent girls (14-year-old with diplegic cerebral palsy and her 15-year-old healthy sister). Outcome measures were traveling distances, time spent outdoors, and Children's Assessment of Participation and Enjoyment questionnaires. Global positioning systems documented that the girl with cerebral palsy did not visit nearby friends, spent less time outdoors and traveled shorter distances than her sister (P = .02). Participation questionnaire corroborated that the girl with cerebral palsy performed most activities at home alone. Lower outdoor activity of the girl with cerebral palsy measured by a global positioning system was 29% to 53% of that of her sibling similar to participation questionnaires (44%). Global positioning devices objectively documented low outdoor activity in an adolescent with cerebral palsy compared to her sibling reflecting participation reported by validated questionnaires. Global positioning systems can potentially quantify certain aspects of participation.

Sustained-release fampridine (4-aminopyridine) in multiple sclerosis: efficacy and impact on motor function

Objective

The aim of this study was to determine the efficacy of sustained-release fampridine (4-aminopyridine) in veterans with multiple sclerosis (MS) with limited ambulatory ability, and its impact on motor function in an outpatient setting.

Design

Retrospective.

Setting

Tertiary referral center [Veterans Affairs (VA) Medical Center].

Participants

Veterans; 20 MS patients were prescribed dalfampridine (10 mg twice daily) due to their difficulty with walking based on patient and caregiver report and clinician impression of change in the ability to ambulate based on prior 10-meter (10M) and 2-minute walk tests (2MWTs).

Intervention

Not applicable.

Main Outcome Measures

The primary outcome measures were mean changes in walking speed (10M walk test), walking distance (2MWT), and Total Functional Independence Measure (TFIM). Improvement of >20 % in walking speed was indicated as a clinically meaningful change.

Results

Treatment with dalfampridine resulted in significant improvement in walking speed and endurance (p < 0.05). Walking speed increased by 33 % and walking endurance by 31 %, representing clinically meaningful improvement. This change was not influenced by change in muscle tone. This improvement in mobility was associated with a clinically significant change in motor function. Adverse effects, including insomnia, dizziness, and headache, were experienced by five patients who discontinued the medication after a minimum of 4 weeks.

Conclusion

Treatment with dalfampridine resulted in clinically relevant improvements in walking speed and endurance in MS patients with limited ambulation and helped improve their motor function.

Electronic supplementary material

The online version of this article (doi:10.1007/s40268-013-0020-x) contains supplementary material, which is available to authorized users.

Gait characteristics of multiple sclerosis patients in the absence of clinical disability

PURPOSE

Motor deficits in lower extremities and gait abnormalities are a major feature of the multiple sclerosis (MS) patients. Patients with minimal clinical disability have subtle gait changes. The aim of this study was to analyze the gait characteristics of MS patients in the absence of clinical disability.

METHOD

A case-control study was carried out with 12 MS patients and 12 matched healthy controls. The subjects underwent a clinical neurological evaluation to determine their disability level (EDSS ≤ 1.5). Then, the subjects were referred for completion self-report questionnaires (gait, perceived balance confidence, physical activity and fatigue), gait clinical trials, and 3D kinematic analysis.

RESULTS

MS patients showed more impairment of perceived fatigue, perceived of walking impact and perceived balance confidence, despite having no disability. Gait characteristics showed no differences when they were determined by clinical observation. The 3D kinematic analysis of gait showed slight but significant changes in ankle movement.

CONCLUSION

MS patients with no clinical disability have discrete changes in gait that can be evidenced by perceived impact on walking and kinematic evaluation, mainly of ankle movement. Moreover, there is a decrease in perceived balance confidence and an increase in perceived fatigue, which are correlated despite having different origins.

Monitoring human health behaviour in one's living environment: a technological review

The electronic monitoring of human health behaviour using computer techniques has been an active research area for the past few decades. A wide array of different approaches have been investigated using various technologies including inertial sensors, Global Positioning System, smart homes, Radio Frequency IDentification and others. It is only in recent years that research has turned towards a sensor fusion approach using several different technologies in single systems or devices. These systems allow for an increased volume of data to be collected and for activity data to be better used as measures of behaviour. This change may be due to decreasing hardware costs, smaller sensors, increased power efficiency or increases in portability. This paper is intended to act as a reference for the design of multi-sensor behaviour monitoring systems. The range of technologies that have been used in isolation for behaviour monitoring both in research and commercial devices are reviewed and discussed. Filtering, range, sensitivity, usability and other considerations of different technologies are discussed. A brief overview of commercially available activity monitors and their technology is also included.

Recommendations for the use of prolonged-release fampridine in patients with multiple sclerosis (MS)

Prolonged-release fampridine (fampridine PR) is a potassium channel blocker that improves conductivity of signal on demyelinated axons in central nervous system. Fampridine PR has been approved to improve speed of walking in patients with multiple sclerosis. This statement provides a brief summary of data on fampridine PR and recommendations on practical use of the medication in clinical practice, prediction, and evaluation of response to treatment and patient management.

The impact of slower walking speed on activities of daily living in patients with multiple sclerosis

AIMS

To identify the relevance and impact of walking speed (WS) over a short distance on activities of daily living (ADLs) in patients with multiple sclerosis (MS).

METHODS

An internet-administered survey of MS patients in four countries was distributed to 605 individuals in 2010. Participants had MS for > 5 years and must have reported difficulty walking as a result of MS. The impact of MS on walking and the effects of WS on ADLs were assessed based upon responses (scored on a scale of 1-10) to five questions and categorised post hoc as: high (8-10), moderate (4-7) or low (1-3) impact/importance.

RESULTS

Of the participants who completed the survey (n = 112), 60% were female patients, 63% were aged ≥ 45 years, and 55% had relapsing-remitting MS. Approximately, half of participants reported a high impact of MS on their general walking ability (46%) and their ability to increase WS over a short distance (55%). Up to 53% of participants reported avoiding ADLs because of concerns about WS; within this cohort, older male patients and patients with secondary-progressive MS were highly represented.

DISCUSSION

These results, which highlight the importance of WS to patients with MS and emphasise the impact of WS on health-related quality of life and ADLs, underscore the importance of clinical measures of WS, such as the timed 25-foot walk, in assessing walking in MS patients.

CONCLUSION

  Walking speed over a short distance has a significant impact on ADLs for patients with MS.

Activities-specific balance confidence in people with multiple sclerosis

Objective. To evaluate the validity of the Activities-specific Balance Confidence scale (ABC) in people with multiple sclerosis (PwMS). Design. A multicentre, cross-sectional study. Setting. Six rural and urban Swedish sites, including specialized units at hospitals and primary care centers. Participants. A sample of 84 PwMS with subjective gait and balance impairment but still able to walk 100 m (comparable with EDSS 1–6). Outcome Measures. Timed Up and Go, Timed Up and Go^cog, 25-foot Timed Walk Test, Four Square Step Test, Dynamic Gait Index, Chair Stand Test, 12-item MS Walking Scale, self-reported falls, and use of assistive walking device were used for validation. Results. The concurrent convergent validity was moderate to good (0.50 to −0.75) with the highest correlation found for the 12-item MS Walking Scale. The ABC discriminated between multiple fallers and nonfallers but not between men and women. Ecological validity is suggested since ABC discriminated between users of assistive walking device and nonusers. The internal consistency was high at α = 0.95, and interitem correlations were between 0.30 and 0.83. Conclusion. This study supports the validity of the ABC for persons with mild-to-moderate MS. The participants lacked balance confidence in many everyday activities, likely restricting their participation in society.

Walking impairment in patients with multiple sclerosis - a new therapeutic approach and clinical potential of dalfampridine extended release tablets

Walking impairment is a clinical hallmark of multiple sclerosis (MS) that has been under-recognized as a therapeutic target for pharmacologic intervention. The development and approval of dalfampridine extended release tablets (dalfampridine-ER; known as prolonged-, modified, or sustained-release fampridine outside the USA), 10 mg taken twice daily, to improve walking in patients with MS, fills a previously unmet need. In three randomized, double-blind, placebo-controlled trials, dalfampridine-ER improved walking speed in approximately one-third (37%) of treated patients, and average walking speed on therapy among these responders improved by approximately 25% relative to baseline. Walking-speed improvement among responders was clinically significant, as determined by a statistically significant improvement in the patient-reported 12-item Multiple Sclerosis Walking Scale. Long-term extension studies indicate that responders were able to maintain benefits, compared with nonresponders over prolonged periods of treatment. Dalfampridine-ER was generally well tolerated. Dizziness, insomnia, balance disorder, headache, nausea, urinary tract infection, and asthenia were the most common adverse events. Although the incidence of seizures appeared to be dose related, among patients treated with dalfampridine-ER in the three trials, the rate of seizures was 0.25%. These efficacy and safety data suggest that dalfampridine-ER can be a useful and clinically relevant addition to the pharmacologic armamentarium for the management of MS symptoms and disabilities. Because of its narrow therapeutic index and potential for seizures, it is especially important in the clinical setting to adhere to the dosing recommended in the approved labels.

Assessing walking disability in multiple sclerosis

Most patients with multiple sclerosis (MS) eventually experience walking disability. The objective of this review was to evaluate the clinical utility of measures specific for walking in MS. Walking assessments had high reliability and were correlated with related measures, including the 12-item multiple sclerosis walking scale (MSWS-12). Shorter timed walking tests (Timed 25-foot Walk (T25FW), 10-metre Timed Walk, 30-metre Timed Walk) measure overall walking disability and are best suited for clinical settings, whereas longer timed or distance tests (100-metre Timed Walk, 6-minute Walk Test, 2-minute Walk Test) are better for the assessment of walking fatigability, distance limitations and functional capacity. The MSWS-12 measures different, but related, aspects of walking than the objective tests. The T25FW is the best characterised objective measure of walking disability and can be used across a wide range of walking disabilities. Additional work is needed to fully characterise the other objective walking assessments 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.

The inter- and intra-unit variability of a low-cost GPS data logger/receiver to study human outdoor walking in view of health and clinical studies

Purpose

The present study evaluates the intra- and inter-unit variability of the GlobalSat® DG100 GPS data logger/receiver (DG100) when estimating outdoor walking distances and speeds.

Methods

Two experiments were performed using healthy subjects walking on a 400 m outdoor synthetic track. The two experiments consisted of two different outdoor prescribed walking protocols with distances ranging from 50 to 400 m. Experiment 1 examined the intra-unit variability of the DG100 (test-retest reproducibility) when estimating walking distances. Experiment 2 examined the inter-unit variability of four DG100 devices (unit to unit variability) when estimating walking distances and speeds.

Results

The coefficient of variation [95% confidence interval], for the reliability of estimating walking distances, was 2.8 [2.5–3.2] %. The inter-unit variability among the four DG100 units tested ranged from 2.8 [2.5–3.2] % to 3.9 [3.5–4.4] % when estimating distances and from 2.7 [2.4–3.0] % to 3.8 [3.4–4.2] % when estimating speeds.

Conclusion

The present study indicates that the DG100, an economical and convenient GPS data logger/receiver, can be reliably used to study human outdoor walking activities in unobstructed conditions. This device let facilitate the use of GPS in studies of health and disease.

The accuracy of a simple, low-cost GPS data logger/receiver to study outdoor human walking in view of health and clinical studies

INTRODUCTION

Accurate and objective measurements of physical activity and lower-extremity function are important in health and disease monitoring, particularly given the current epidemic of chronic diseases and their related functional impairment.

PURPOSE

The aim of the present study was to determine the accuracy of a handy (lightweight, small, only one stop/start button) and low-cost (∼$75 with its external antenna) Global Positioning System (GPS) data logger/receiver (the DG100) as a tool to study outdoor human walking in perspective of health and clinical research studies. Methods. Healthy subjects performed two experiments that consisted of different prescribed outdoor walking protocols. Experiment 1. We studied the accuracy of the DG100 for detecting bouts of walking and resting. Experiment 2. We studied the accuracy of the DG100 for estimating distances and speeds of walking.

RESULTS

Experiment 1. The performance in the detection of bouts, expressed as the percentage of walking and resting bouts that were correctly detected, was 92.4% [95% Confidence Interval: 90.6-94.3]. Experiment 2. The coefficients of variation [95% Confidence Interval] for the accuracy of estimating the distances and speeds of walking were low: 3.1% [2.9-3.3] and 2.8% [2.6-3.1], respectively.

CONCLUSION

The DG100 produces acceptable accuracy both in detecting bouts of walking and resting and in estimating distances and speeds of walking during the detected walking bouts. However, before we can confirm that the DG100 can be used to study walking with respect to health and clinical studies, the inter- and intra-DG100 variability should be studied.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00485147.

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.

Evaluating walking in patients with multiple sclerosis: which assessment tools are useful in clinical practice?

Walking limitations are among the most visible manifestations of multiple sclerosis (MS). Regular walking assessments should be a component of patient management and require instruments that are appropriate from the clinician's and the patient's perspectives. This article reviews frequently used instruments to assess walking in patients with MS, with emphasis on their validity, reliability, and practicality in the clinical setting. Relevant articles were identified based on PubMed searches using the following terms: "multiple sclerosis AND (walking OR gait OR mobility OR physical activity) AND (disability evaluation)"; references of relevant articles were also searched. Although many clinician- and patient-driven instruments are available, not all have been validated in MS, and some are not sensitive enough to detect small but clinically important changes. Choosing among these depends on what needs to be measured, psychometric properties, the clinical relevance of results, and practicality with respect to space, time, and patient burden. Of the instruments available, the clinician-observed Timed 25-Foot Walk and patient self-report 12-Item Multiple Sclerosis Walking Scale have properties that make them suitable for routine evaluation of walking performance. The Dynamic Gait Index and the Timed Up and Go test involve other aspects of mobility, including balance. Tests of endurance, such as the 2- or 6-Minute Walk, may provide information on motor fatigue not captured by other tests. Quantitative measurement of gait kinetics and kinematics, and recordings of mobility in the patient's environment via accelerometry or Global Positioning System odometry, are currently not routinely used in the clinical setting.

Predicting habitual walking performance in multiple sclerosis: relevance of capacity and self-report measures

The objective was to establish the extent to which physical functioning capacity and self-report measures are able to predict the habitual walking performance in ambulatory persons with multiple sclerosis. Fifty persons with multiple sclerosis (Expanded Disability Status Scale, EDSS, 1.5-6.5) were tested on leg muscle strength as well as walking and balance capacity, and completed self-report indices on perceived physical functioning. Habitual walking performance, that is, the real amount of steps that is performed in the customary living environment, was registered by means of an ambulant accelerometer-based monitor during seven consecutive days. Mild (EDSS 1.5-4.0, n = 29) and moderate (EDSS 4.5-6.5, n = 21) multiple sclerosis subgroups were additionally distinguished as predictor variables and values were hypothesized to differ depending on multiple sclerosis severity and concomitant ambulatory function. Multiple regression analyses yielded a single most significant predictor for each (sub)group with other variables making no independent contribution to the variation in habitual walking performance. For the total study sample, this was the 6-Minute Walking Test (R(2) = 0.458, p < 0.01). In the mild multiple sclerosis subgroup, the 6-Minute Walking Test was again most predictive, yet to a modest degree (R(2) = 0. 187, p = 0.02). In the moderate multiple sclerosis subgroup, the 2-Minute Walking Test explained over half of the variance (R(2) = 0.532, p < 0.01). Habitual walking performance is best reflected by longer walking capacity tests. The extent to which it can be predicted based on clinical testing is larger in a multiple sclerosis patient sample with more severe walking disability. Ambulatory monitoring, however, includes aspects of community ambulation not captured in the clinic, and must be considered as an additional outcome for evaluating interventions in multiple sclerosis.

[4-Aminopyridine (Fampridine). A new attempt for the symptomatic treatment of multiple sclerosis]

Mobility limitation is a frequent clinical symptom of multiple sclerosis (MS) that poses a therapeutic challenge. For years results of animal experiments and clinical experience have indicated that the potassium channel blocker 4-aminopyridine improves axonal excitatory circuits and thus muscular strength in demyelinating diseases. A recently conducted randomized, placebo-controlled, multicenter phase 3 clinical trial in MS patients was able to show that an oral sustained-release formulation of 4-aminopyridine (Fampridine-SR) represents a suitable agent for treatment of walking disability in MS patients.This overview presents the study data and discusses the value of 4-aminopyridine for the symptomatic treatment of MS as a neurofunctional modifier of this disabling disease.

Sustained-release oral fampridine in multiple sclerosis: a randomised, double-blind, controlled trial

BACKGROUND

Clinical studies suggested that fampridine (4-aminopyridine) improves motor function in people with multiple sclerosis. This phase III study assessed efficacy and safety of oral, sustained-release fampridine in people with ambulatory deficits due to multiple sclerosis.

METHODS

We undertook a randomised, multicentre, double-blind, controlled phase III trial. We randomly assigned 301 patients with any type of multiple sclerosis to 14 weeks of treatment with either fampridine (10 mg twice daily; n=229) or placebo (n=72), using a computer-generated sequence stratified by centre. We used consistent improvement on timed 25-foot walk to define response, with proportion of timed walk responders in each treatment group as the primary outcome. We used the 12-item multiple sclerosis walking scale to validate the clinical significance of the response criterion. Efficacy analyses were based on a modified intention-to-treat population (n=296), which included all patients with any post-treatment efficacy data. The study is registered with ClinicalTrials.gov, number NCT00127530.

FINDINGS

The proportion of timed walk responders was higher in the fampridine group (78/224 or 35%) than in the placebo group (6/72 or 8%; p<0.0001). Improvement in walking speed in fampridine-treated timed walk responders, which was maintained throughout the treatment period, was 25.2% (95% CI 21.5% to 28.8%) and 4.7% (1.0% to 8.4%) in the placebo group. Timed walk responders showed greater improvement in 12-item multiple sclerosis walking scale scores (-6.84, 95% CI -9.65 to -4.02) than timed walk non-responders (0.05, -1.48 to 1.57; p=0.0002). Safety data were consistent with previous studies.

INTERPRETATION

Fampridine improved walking ability in some people with multiple sclerosis. This improvement was associated with a reduction of patients' reported ambulatory disability, and is a clinically meaningful therapeutic benefit.

Efficacy and safety of a hip flexion assist orthosis in ambulatory multiple sclerosis patients

OBJECTIVE

To evaluate the efficacy and safety of a hip flexion assist orthosis (HFAO) in ambulatory patients with multiple sclerosis (MS).

DESIGN

Fourteen week pre- and postintervention uncontrolled trial.

SETTING

Outpatient rehabilitation clinic within an MS center.

PARTICIPANTS

Ambulatory MS patients (N=21) with unilateral (or unilateral predominant) hip flexor weakness.

INTERVENTION

Subjects were fitted with the HFAO on the weaker side, trained to use the device, and given a wear schedule. Subjects completed 2 baseline evaluations and follow-up testing at 8 and 12 weeks.

MAIN OUTCOME MEASURES

Lower-extremity manual muscle testing, pain, and gait performance (Timed 25-Foot Walk, Timed Up & Go, 6-minute walk test, Mellen Center Gait Test). Subject satisfaction was evaluated by using a 9-item custom questionnaire.

RESULTS

There was a statistically significant improvement of strength in the affected lower extremity at 8 and 12 weeks (effect size [ES]=0.63; ES=1.32, respectively), of pain at 12 weeks only (ES=-0.64), and of all gait tests at 8 and 12 weeks (ES range, 0.38-1.33). The overall mean satisfaction score at 12 weeks was 39 (maximum score, 45). No serious adverse events were recorded during the study. The most frequent side effect of the HFAO was low back pain (19%). No side effects led to discontinuation of the HFAO use during the study.

CONCLUSIONS

The HFAO was safe and well tolerated. HFAO use was associated with significant improvement of gait performance as well as improvement of strength in the lower extremity fitted with the HFAO. Subjective reports suggest that there was an increase in daily life activity level.

Physiotherapy and related activities in multiple sclerosis

There are now about 50 randomized controlled trials into rehabilitation packages, physiotherapy or related specific and non-specific techniques in multiple sclerosis (MS). Generally these, and related systematic reviews, report benefits. Particular problems arise, however, with the blinding of assessment, determination of what is the active or beneficial input by the therapist, the use of multiple domains of assessment of quality of life and function without, sometimes, a clear statement of a trial hypothesis or primary outcome and the short-term nature of many studies. Therapy inputs can be broadly broken down into verbal interactions with the patient, physical inputs and referral/recommendation processes. Each may be relevant to the outcome. ‘Response-shift’ may be an important internal mechanism of mind whereby changes in ‘quality of life’ may not always parallel function emphasizing the case for clearly separating quality of life from functional assessment and attempting to make the latter as objective as possible. Trials of such complex interventions will need to randomize specified components of therapy against appropriate placebos or active treatment arms rather than no therapy, which will be ethically harder to sustain. Classification of physiotherapy inputs by type and ‘dosage’, a primary hypothesis under test and attention to concealed allocation of treatment, assessor blinding and intention to treat analysis together with improved measurements of function will assist in the consolidation of the evidence base for physiotherapy as an important component of management for MS patients.