Determination of Walking Impairment in Multiple Sclerosis Figure 1: Diagram of the Test Field for the Six Spot Step Test
1m
1m 5m
2m
The subject tested starts by standing on the circle at the left end of the field. The five wooden blocks are placed in the centre of the remaining circles. The subject walks criss-cross from one circle to the next while shoving the blocks out of the circles and the test field. The same leg is used for all blocks in one passage. The test is performed twice with each leg as the active limb.39
Another assessment of outcome is the MS Functional Composite (MSFC).15,16
This test involves three quantitative components: a timed 25-foot walk (T25FW) to measure leg function and ambulation, a nine- hole peg test (9HPT) to measure arm and hand function and the Paced Auditory Serial Addition Test (PASAT) to measure cognitive function. These three components are used to produce a combined Z-score that indicates the overall relative difference from the mean of a non-diseased population. The reliability of the MSFC was demonstrated in a small study of 10 MS patients at a treatment centre in the US.17 Repeated tests conducted by two technicians showed that the MSFC provided excellent reproducibility in terms of intra- and inter-rater variability. In another study, the T25FW and 9HPT were repeated for five consecutive days in 63 patients with MS from four different university treatment centres in the US. The results showed a
It was concluded that changes >20% in MSFC
scores were needed to reliably indicate a true change in function for a patient. This represents a substantial change in status and a weakness of this scoring system, which might not detect smaller or more subtle deteriorations in a patient’s condition and may thus fail to alert the clinician to the need for improved treatments or support.
There are many other tests for assessing general MS status. Some of these are designed to assess HRQoL, e.g. the Family Assessment of MS Trial Outcome Index (FAMS-TOI), comprising the dimensions mobility, symptoms, emotional wellbeing, general contentment, thinking and fatigue, family and social wellbeing and additional concerns.19
Specifically designed for assessing patients diagnosed with MS, this scale provides a comprehensive determination of disease status; the mobility subscale is highly predictive of EDSS and has been used in large-scale MS trials.20
Other tests used in MS
populations were designed to be used in various diseases affecting neurological abilities: the Health Utilities Index Mark 3 (HUI3), which assesses eight aspects of disease effects;21
(MSIS-29), which addresses physical and psychological impact in two separate subscales;22
and the Short Form-36 (SF-36).23,24 the MS Impact Scale-29 The latter was
primarily designed to assess various aspects of QoL in many different diseases and populations, with 25% (nine out of 36) of the questions relating to mobility (see Table 1). While these instruments provide good overall assessments of disease, the determination of mobility in each is inherently limited and the tests are considered by many to be insufficiently precise, or inappropriate, for accurately monitoring progression of mobility in MS patients. The perceived shortcomings in general disability test methods to specifically assess mobility in MS
EUROPEAN NEUROLOGICAL REVIEW
patients led some neurologists to call for improved methods and assessment scales to more precisely determine the parameters associated with walking ability, and for mobility to be more generally recognised as a major indicator of MS progression.7,25
Methods for Assessing Mobility and Gait in Multiple Sclerosis
Mobility tests are mostly simple, requiring minimal equipment or facilities, and can be completed within a few minutes. An overview of the more frequently used tests is given in Table 3. Some of these tests include an assessment of gait, a vital and complex factor influencing walking ability. Gait is affected by strength, motor control, range of motion and sensation. In MS, there is no one gait type that is characteristic of the disease, although some frequent gait features have been observed.26,27
A consensus meeting sponsored by the Consortium of MS Centers (CMSC) in 2009 developed recommendations for the determination of gait in MS.4
It was agreed that this complex function can only be assessed by measuring a range of parameters. The participants recommended a set of five mobility tests considered to form a useful preliminary measure of gait in MS: T25FW, Dynamic Gait Index (DGI), 12-Item MS Walking Scale (MSWS-12), Timed Up and Go Test (TUGT) and the Six-Minute Walk (6MW). All of these assessments are easy to perform, require minimal equipment and provide reliable and valid data; some lack accurate assessment of gait and some require clinician training.
The MSWS-12 is a prominent example of a walking-ability test specifically developed for MS patients.1
The test consists of 12 questions
related to walking and running ability and the requirement for support. Responses are graded from 1 (ability not limited at all) to 5 (extremely limited ability). The test method was evaluated in a group of 78 patients with primary progressive MS (PPMS) and a separate group of 54 patients with PPMS (n=1), SPMS (n=16) or RRMS (n=37) who were receiving steroid treatment for relapses. The MSWS-12 findings in all patients were highly reproducible, and relative efficiency determinations showed the MSWS-12 to be more responsive (relative efficiency [RE] 1.0) than the FAMS-TOI mobility scale (RE 0.76), the SF-36 (RE 0.48), the EDSS (RE 0.31) and the T25FW (RE 0.64).
The DGI is a frequently used test, originally developed to assess the risk of falling, which comprises eight sets of tasks to assess various
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