Quantitation of McArdle's Sign and Evaluation of Specificity for Multiple Sclerosis

Study Overview
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Brief Summary
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The study is designed to quantitate McArdle's sign, an increase in measurable weakness with neck flexion described in patients with multiple sclerosis, and to determine whether it is or is not specific for multiple sclerosis.

Detailed Description
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Finger strength will be measure using a torque-measuring device designed to quantitate finger extension strength. The device was designed for point of treatment use, patient safety and portability. Strength will be measured in 5 paired trials, first with neck extended and then with neck flexed. Two protocols will be evaluated, one testing isometric strength against a fixed resistance and the second testing strength against dynamic resistance. McArdle's sign is the difference between strength with neck extension and strength with neck flexion. The data will be digitally registered and dynamic neck position will be recorded electronically in real time. Graphs of dynamic changes in torque versus neck position will be generated and superimposed. Strength will be quantitated using Matlab software. Consecutive patients with myelopathy of any cause with detectable finger extensor weakness will be studied, either due to MS or due to other cause of myelopathy (other inflammatory, vascular, compressive, neoplastic and other). Additionally, normal controls will be studied as will patients with finger extension weakness due to peripheral nerve lesions.

Official Title
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Quantitation of McArdle's Sign and Evaluation of Specificity for Multiple Sclerosis

Conditions
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Multiple Sclerosis

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Myelopathy of any cause with finger extension weakness Patients with peripheral neuropathy with finger extension weakness Healthy controls Exclusion Criteria: Pregnant subjects.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Myelopathy of any cause<br>Male or female 18 years or older with myelopathy and detectable finger extension weakness due to 1) prototypic multiple sclerosis (N=50) 2) other etiologies of myelopathy (N=50), including other inflammatory conditions (e.g. idiopathic transverse myelitis, neuromyelitis optica, acute disseminated encephalomyelitis, sarcoidosis) or other etiologies (compression, vascular disorders, degenerative disorders, neoplasms). | |
| Peripheral neuropathy<br>Male or female 18 years or older with C7 radiculopathy, radial neuropathy, plexopathy, peripheral neuropathy, who have detectable finger extension weakness. | |
| Healthy Controls<br>Male and female 18 year or older with no finger extension weakness and no known neurological conditions. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in quantitative measure of strength between extended positions of the neck and fully flexed position of the neck (McArdle's sign) | Comparison of means and medians of the difference in strength in the fully extended and fully flexed positions (McArdle's sign) measured using a torque measurement device between multiple sclerosis versus other myelopathy and between multiple sclerosis and normal controls; measurements are done in 5 successive trials of extension and flexion and the mean percentage difference between extension and flexion of the last 4 trials is averaged to calculated the McArdle's sign; the goal is to determine whether there is a specific level of McArdle sign that is diagnostic for MS using receiver operator curve method. | through study completion, an average of 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Relative sensitivity of clinical versus instrument-based detection of McArdle's sign. | Compare the clinical detection of the sign by the referring clinician and technician compared to the device-determined McArdle's sign | through study completion, an average of 1 year |