Baker, Spencer; Charles, Steven (Brigham Young University)
Faculty Advisor: Charles, Steven (Ira A. Fulton College of Engineering, Mechanical Engineering)
Essential tremor is one of the most common movement disorders and affects millions nationwide. Its debilitating effects and lack of satisfactory treatments accentuates the need for new tremor-suppressing methods. Alternative treatments are possible but would be more effective if tremor propagation from neurological activity to joint movement was better understood. The purpose of this research was to further develop previous investigations and discover the effects deep upper limb muscles on tremor propagation.
A model of the upper limb was developed to simulate tremor propagation from neural drive to muscle force, joint torque, and degree of freedom movement. An analysis of the model revealed four tremor propagation principles. (1) Musculoskeletal dynamics spread neural drive to multiple outputs, act as a low-pass filter in the tremor bandwidth, and cause a phase shift between muscle activity and joint movement. (2) Tremor spreads primarily due to inertia and secondarily due to moment arm geometry. (3) Tremor spreads narrowly. (4) The degree of freedom most affected by the tremor is wrist flexion-extension.
These conclusions provide new information regarding the propagation of tremor from superficial and deep upper-limb muscles, lay the foundation for determining the muscular source of tremor, and will assist in future tremor treatments.