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Quantitative assessment of upper limb motor function in Multiple Sclerosis using an instrumented Action Research Arm
Ilaria Carpinella1, Davide Cattaneo, Maurizio Ferrarin
1Biomedical Technology Department, Found, Don C, Gnocchi Onlus, IRCCS, Via Capecelatro 66, 20148 Milan, Italy. icarpinella@dongnocchi.it.
Journal of Neuroengineering and Rehabilitation
|April 22, 2014
Summary
An instrumented Action Research Arm Test (ARAT) using inertial sensors accurately detects subtle arm impairments in Multiple Sclerosis (MS) patients, even those missed by traditional clinical scores. This technology offers a sensitive and objective method for assessing arm function in MS.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Rehabilitation Medicine
Background:
- Arm impairment is a common challenge for individuals with Multiple Sclerosis (MS).
- The traditional Action Research Arm Test (ARAT) assesses upper limb function but has limitations in objectivity and sensitivity to mild impairments.
- An instrumented approach to ARAT is proposed to enhance the assessment of arm function in MS.
Purpose of the Study:
- To develop and validate an instrumented version of the ARAT using inertial sensors.
- To objectively quantify arm movement duration and smoothness in MS patients.
- To compare the sensitivity of the instrumented ARAT with traditional clinical assessments.
Main Methods:
- 12 healthy volunteers and 21 MS subjects performed ARAT tasks while wearing a wrist-mounted inertial sensor.
- Accelerometer and gyroscope data were used to calculate task duration, sub-phase timing, and a jerk index for movement smoothness.
- Z-scores quantified deviations from normative data, and correlations with clinical scores (ARAT, 9HPT, FTRS) were analyzed.
Main Results:
- MS patients exhibited significantly longer ARAT task durations (70% increase) and reduced smoothness (16% jerk increase) compared to controls.
- These kinematic alterations were primarily observed in manipulation, transport, and release sub-movements.
- Instrumented ARAT parameters showed strong correlations with clinical scores and identified subtle impairments not detected by the standard ARAT.
- Reduced velocity and smoothness were evident even in MS patients with normal ARAT scores.
Conclusions:
- The instrumented ARAT effectively differentiates between control and MS groups.
- This method reveals subtle arm functional deficits in MS that traditional ARAT may miss.
- High correlations between instrumental variables and clinical ratings validate the instrumented ARAT as a sensitive, quick, and easy-to-use tool for quantifying arm function in MS.
