頸部肌肉與脊柱對於頸部之穩定性影響

Abstract

日常生活中頸部的動作頻繁，因此維持其穩定性以保護頭部是一個重要課題。維持脊椎穩定度必須依賴正常的肌肉和椎體的功能。然而，頸部為複雜的肌肉骨骼系統，欲了解頸部肌肉和椎體本身如何提供頸椎穩定度，有相當的難度。本研究主要的目的即在於探討頸部肌肉和頸椎椎體在維持頸椎穩定度中所扮演的角色。 本研究包含臨床試驗與體外實驗兩個部分。臨床試驗部分使用兩項指標，即肌肉共同收縮比 (co-contraction ratio)和自主活動反應指數 (voluntary response index)，來分析正常人及慢性頸痛病人在頸部自主活動時的肌電圖模式。體外實驗部分使用自製的脊椎測試機，來研究肌肉功能缺損與椎間盤退化，對於頸椎穩定度的影響。 臨床試驗的結果顯示，活動的方向與速度，皆會影響頸部肌肉的活化程度及控制模式; 而在快速的頸部活動時，頸椎穩定度會降低。另外，慢性頸痛病人的位置精確度較正常人差、肌肉控制模式也有顯著改變。體外實驗的結果則顯示，頸部肌肉功能缺損對於頸椎穩定性的影響，會較椎間盤退化對頸椎的影響更顯著。 總結而言，本研究由健康人的頸部肌電圖，呈現正常肌肉活動維持頸椎穩定性的模式。病人在復位動作的位置精確度較差則可能是由於不正常的肌肉控制模式所致。體外實驗顯示了不同肌肉條件與椎體狀態對於穩定性的影響。本研究呈現了量化脊椎的動態穩定度、以及在體外實驗中模擬各種脊椎退化症的可能性。未來的研究可進一步探討如何加強臨床試驗與體外實驗的連結。

Stabilization of cervical spine is required in daily life activities to protect the neck-head complex. Maintaining the stability of spine relies on proper muscle activations and spinal column function. However, the redundant musculoskeletal system makes it difficult to understand the effect of cervical muscle recruitments and intrinsic resistance of spine mainly provided by intervertebral discs on the spinal stability. Therefore, the primary purpose of this dissertation was to investigate the roles of cervical muscles and spinal column on the stability of cervical spine. This dissertation included both in vivo and in vitro experiments. Two electromyographic data analysis methods (co-contraction ratio and voluntary response index) were used for clinical studies to evaluate the cervical muscle activation pattern of healthy subjects and patients with chronic neck pain during neck motions. The spine testing apparatus was used for the in vitro experiment to examine the effects of subfailure of two stabilization systems (muscle dysfunction and disc degeneration) on the cervical spine stability. The results from in vivo experiments indicated that the activation level and control pattern of cervical muscles were affected by movement speeds and directions and that the cervical spine stability may decrease during faster movements. Besides, patients with chronic neck pain demonstrated impaired position accuracy and altered EMG pattern during reposition from either flexed or extended head position. The results from in vitro experiment indicated that muscle dysfunction had a significantly greater effect on spinal stability when compared to disc degeneration. In conclusion, the electromyographic patterns of healthy subjects in this dissertation revealed the normal muscle activation pattern in maintaining the spinal stability. The poor position accuracy in patients during reposition movements could be attributed to the altered neuromuscular control patterns. The in vitro experiment showed how the spinal stability was affected by the muscle dysfunction and disc degeneration. Future studies are needed to investigate the association between the in vivo and the in vitro measurements.