Graduation Year

2021

Document Type

Thesis

Degree

M.S.M.E.

Degree Name

MS in Mechanical Engineering (M.S.M.E.)

Degree Granting Department

Mechanical Engineering

Major Professor

Kyle B. Reed, Ph.D.

Committee Member

Daniel P. Hess, Ph.D.

Committee Member

Stephen Aradi, Ph.D.

Keywords

Clinical Device, Fast Fourier Transform, Friedreich's Ataxia, Gait Velocity, Rating Scale, Vibratory Sense

Abstract

Clinical rating scales play a major role in assessing progressive neurological diseases. Neurologists use these rating scales to provide a better diagnosis, to provide a better treatment plan, and to analyze the outcome of clinical trials. Friedreich’s ataxia (FA) is a neurodegenerative disease that causes ataxia in limbs, speech impairment, and polyneuropathy. Since FA is a progressive disease, various rating scales have been standardized to provide an objective assessment of the patient’s current condition. The Friedreich Ataxia Rating Scale (FARS) includes several tests to capture neurological features of FA and to assess the functional stage of ataxia. The rubrics used to grade these tests are highly subjective, and thus prone to human error.

This thesis focuses on three devices designed to quantify three tests (heel to shin tap, 25-ft walk test, and vibratory sense) mentioned in the FARS rating scale. This thesis focuses on quantifying the help to shin tap, 25 ft walk test, and the vibratory sense test outlined in the FARS rating scale. These devices were engineered to accurately perform these tests using the current exam procedures. Along with each device, each test was manually graded by the evaluator to estimate the human error introduced while testing.

The heel to shin tap device was found to be very precise while conducting the tests on healthy individuals in this study (average absolute error = 0). However, an average absolute error of 0.4118 (successful taps) was estimated in the trials conducted on ataxia patients. This error was either a result of undershoot/overshoot in the number of successful taps reported by the device. Since the device did not report any error while testing healthy individuals, it was concluded that the sensor used in this device was not accurate enough to quantify the taps.

The 25 ft walk test device showed promising results in the tests conducted on all the subjects. The average absolute error in timing the FARS test using this device was estimated to be 0.45 seconds. In addition to that, the data obtained from this device was used to extract gait velocity to provide a more objective assessment of the test. The results of this study showed that gait velocity might be a key parameter in grading this walk test.

The vibratory sense device was found to be inaccurate for most of the tests conducted using this device. This might have been a result of the noise introduced while capturing the data. This issue was fixed by adding an analog filter to the circuit for noise removal during the later stages of testing. The results of the tests conducted after this fix shows that the data obtained from this device can be used to quantify the vibrations in the tuning fork in terms of amplitude of the vibration. However, since only a few tests were conducted after calibrating this device, more testing is required to evaluate its performance.

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