Study to Evaluate the Reliability and Validity of the Modified Manual Muscle Test for Persons With MS

Background In Switzerland, many patients with multiple sclerosis (MS) are treated with physiotherapy. Muscle weakness is a common symptom. Particularly in progressive disease courses, motor dysfunction is a major contributor to the reduced mobility and quality of life. Therefore, improving the motor dysfunction is an important goal for therapy and is evaluated with a variety of muscle function tests. The 6 level British Medical Research Council (BMRC) manual muscle test is the most widely used test in MS and is a part of the Neurostatus-Expanded Disability Status Scale (EDSS) assessment, which has been adopted as the standard in most of the pivotal trials that have led to the approval of the current MS treatments. In MS patients, testing muscle function can be confounded by many factors, such as spasticity and ataxia, which are not considered by the existing tests and may cause biased test results. Steinlin Egli described a Modified Manual Muscle Test (MMMT) that considers spasticity and may provide a more reliable and valid muscle function test for MS patients.

Aim of the study is to evaluate the inter- and intra-rater reliability of the Modified Manual Muscle Test in MS and evaluate the validity of the Modified MMT according to the criteria of the Neurostatus BMRC manual muscle test and the microFET2 handhold dynamometer.

Methods This is a single-centre, prospective cross-sectional study with a test-retest design. The Neurostatus BMRC manual muscle test and the microFET2 hand held dynamometer are used as the criteria. The primary endpoint is the ordinal MMMT level. The intra-class correlation coefficient (ICC) of the ranked MMMT levels will be estimated. The investigator aims to show that the MMMT results are clinically relevant with a high level of ICC.

The secondary endpoints include the Neurostatus BMRC levels, the muscle strength as measured by the microFET2 dynamometer and fatigue using a numeric rating scale (NRS). Subgroup analyses will determine whether the MMMT is less sensitive to the influence of spasticity than the Neurostatus BMRC.

28 patients with MS will be tested in 2 days. In each day, six examiners will test seven patients in the morning and seven patients in the afternoon. Three MS-therapists from the Specialized Group Physiotherapy in MS and three neurologists from the Department of Neurology at the University Hospital Basel will be tester. All examiners will be blinded to the results of the other examiners. All test persons will be blinded to their test results. First, the patient will rate his fatigue using the NRS. Muscle function will be tested with the microFET2 and spasticity will be assessed using the modified Tardieu Scale. Then, the first round of manual testing will be executed. After each test, there will be a break that is long enough for the patients to recuperate. The order of the examiners will be randomized. The retest round will proceed in a different order. Finally, spasticity will be tested again using the modified Tardieu Scale, and the patients will rate their fatigue.

Statistical Analysis The study data will be analysed using the internet-based program R. The descriptive statistics will describe the sample characteristics. The inter-rater reliability will be estimated by the ICC of the MMMT ranks. The ICC will be estimated by a two-way random-effects ANOVA and reported with 95% CI. If the lower limit of the CI is larger than the pre-specified clinically relevant ICC margin, the MMMT will be considered a reliable tool for evaluating muscle strength in MS patients.

The inter-rater reliability the Neurostatus BMRC will be estimated similarly by the ICC. The ICC of both tests will be compared. The test-retest reliability of the MMMT and Neurostatus BMRC will be estimated using two-way random-effects ANOVA and will be reported by ICC estimates. The influence of potential fatigue will be analysed by plotting the test and retest results against the NRS and investigating the associations and interactions using a linear mixed effects model. The pairwise correlations of the MMMT and the Neurostatus BMRC with the microFET2 will be graphically analysed (scatterplots and/or boxplots), and Spearman's ρ will be calculated. The primary and secondary analyses will be repeated for subgroups with high and low spasticity patients to compare the sensitivity of the MMMT and Neurostatus BMRC to spasticity.

Expected results: The investigators expect the MMMT for MS to be a reliable and valid manual muscle function test that can be used in the evaluation of the long-term treatment of MS patients with physical therapy.

Inclusion criteria

• diagnosed with MS according to the McDonald criteria
• EDSS between 0 and 6.5
• older than 18 years of age.

Exclusion criteria

• An acute episode of MS within 3 months prior to the testing,
• grave cognitive changes
• distinct fatigue
• a history of current back, neck or elbow pain