Tremor Suppression With Mechanical Vibration Stimulation

Wenbin Liu,Kazuo Kiguchi,Takeru Kai

doi:10.1109/access.2020.3045023

Abstract

Tremor, which is one of the most common movement disorders, is a repetitive movement that is caused by periodic muscle contraction and relaxation. To suppress tremors of upper-limb tremor patients, such as essential tremor (ET) patients, many kinds of devices have been developed. On the other hand, when mechanical vibration stimulation is applied to a human muscle, sustained muscle contraction, which is referred to as the tonic vibration reflex (TVR), is induced in the stimulated muscle. In this study, a novel tremor suppression method that utilizes the periodic TVR to induce muscle contraction/relaxation to generate the counterphase motion of the ET is proposed and applied to the forearm pronation-supination ET. In the proposed method, periodic vibration stimulation is applied to generate the periodic TVR in the pronator teres muscle and/or supinator muscle. First, the results confirmed that the TVR can be induced by applying mechanical vibration stimulation to the pronator teres muscle and supinator muscle since the forearm pronation-supination tremor is one of the key features of the ET. Furthermore, the findings also confirmed that the TVR intensity that is induced in these muscles can be adjusted by changing the vibration stimulation frequency. Second, the results show that the counterphase motion of the ET (i.e., periodic pronation-supination motion) can be generated by applying the proposed method. The effectiveness of the proposed method for tremor suppression is evaluated by comparing the generated motion with the ET motion.

Highlights

Tremor, which is one of the most common movement disorders detected in human pathology, is an involuntary, rhythmic, and shaking movement in one or more parts of the human body; it is distinct from other movement disorders by its regular amplitude and frequency [1][2]
Experiment-1 was carried out for two purposes: the first purpose was to confirm that a pronation/supination motion was induced by adding continuous mechanical vibration stimulation; the second purpose was to confirm the amount of generated pronation-supination motion (i.e., tonic vibration reflex (TVR) intensity) was adjusted by changing the frequency of the added continuous vibration stimulation
In the results of all subjects, the average absolute value of the amount of generated movement in trial B was larger than that in trial A. These results suggest that the TVR intensity induced in the supinator muscle is larger than that in the pronator teres muscle with the same vibration stimulation frequency

Summary

Introduction

Tremor, which is one of the most common movement disorders detected in human pathology, is an involuntary, rhythmic, and shaking movement in one or more parts of the human body; it is distinct from other movement disorders by its regular amplitude and frequency [1][2]. Tremors may affect the movement of the arms, head, trunk and legs, most tremors occur in the hands [3]. Essential tremor (ET), which is one of the postural and kinetic tremors, is the most common pathological tremor with a frequency between 4 and 8 Hz [1][4]. ET constantly occurs when hands are held in posture and/or during voluntary movement, so ET patients sometimes suffer from performing work or simple daily tasks, such as eating, writing or personal hygiene. The detailed source and mechanism of ET are still not known, and the genetic defects that cause pathological oscillations have not been identified [5], which hampers the effectiveness of existing therapies of tremor suppression, and the development of novel therapies

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Conclusion