頭部假體模型之加速度變化分析

Abstract

人體的平衡主要由三大系統負責：本體感覺、視覺以及前庭系統，前庭系統功能若失常，人體便可能產生不平衡之感覺。為了評估前庭系統的功能，科學家在上個世紀末發明了前庭誘發性肌電位(vestibular evoked myogenic potential，簡稱VEMP)檢查，作為一種電生理的診斷工具。 oVEMP是VEMP的一項分支，其檢查的過程是以人工方式在頭部產生振動波，使前庭內的耳石器官接收到線性加速度變化，經由前庭-動眼反射(vestibulo-ocular reflex, VOR)記錄眼外肌之肌電位變化，透過分析體表肌電位反應以評估前庭系統功能。然而oVEMP尚有許多未釐清的問題，例如振動頭部的位置並非適用於所有受試者，以及誘發之肌電位變化不固定等，上述問題可能牽涉到頭部結構的差異，導致前庭接收到之加速度變化不同。 為釐清上述問題，本研究主要有二項目的，首先為設計一可產生振動和測量加速度之系統，其二為探討簡化之頭部假體模型中影響加速度的物理因素，並在逐步改變變因時，測量不同條件下的加速度變化。 本研究成功設計了能與市售振動器和資料擷取裝置結合的完整系統，亦設計了可更改前額竇結構的頭部假體模型，透過分析實驗結果，本研究提出可能的假說，即振動位置才是主要影響加速度變化之因素，且前額竇影響的變化僅在特定範圍內，此結果可替未來相關領域的研究提供參考。

There are three systems responsible for the balance of a human body: proprioception, vision, and the vestibular system. If the vestibular system is abnormal, it is not possible for anyone to keep well balanced. A diagnostic tool which is named ocular vestibular evoked myogenic potential (oVEMP) examination was developed to evaluate the function of the vestibular system at the end of the 20th century. The process of examination is to artificially generate vibration waves on the head, so that the otolithic organs in the vestibule receive linear acceleration changes, and then by vestibulo-ocular reflex (VOR), the extraocular muscles are subjected to changes in myogenic potential, and the vestibular system function is evaluated by analyzing the surface myogenic potential response. However, many issues of oVEMP remain to be clarified. For example, the position of the head vibration is not suitable for all subjects, and the changes in the induced myogenic potential are not universal. The above problems may involve differences in head structure, resulting in the differences of acceleration changes received by the vestibule. To clarify the above problems, there are two main purposes in this study, firstly to design a system that can generate vibration and measure acceleration, and secondly to explore the geometric factors affecting acceleration in a simplified head dummy model. When the factor is changed quantitatively, the corresponding change of acceleration is measured. In this study a complete platform that is composed of a commercial vibrator and a data acquisition system has been implemented. Also a head dummy model that the structure of frontal sinus in it can be changed has been designed. By analyzing the experimental results, this study proposes a possible hypothesis that the vibration position is the main factor that can influence acceleration changes, and the change of the frontal sinus is a minor factor. This result can provide reference for future research in related fields.