頸椎脊髓神經病變患者之站立姿態控制研究

Abstract

背景：頸椎脊髓神經病變是近年來常見的退化性疾病，其會造成姿勢控制能力受損。而頸部減壓手術為針對頸椎脊髓神經病變的治療之一，其以侵入性方式直接去除造成脊髓壓迫的組織。然而，針對頸椎脊髓神經病變之功能性評估及站立時的姿勢控制之間的關係仍很少被探討，此外，過去也無研究探討頸椎脊髓神經病變患者在減壓手術前後之站立姿勢控制變化。 研究目的：（1）確立頸椎脊髓神經病變患者之功能性表現和站立姿勢控制能力的相關性，並比較不同程度之頸椎脊髓神經病變患者、頸椎神經根病變患者及健康對照者的平衡能力;（2）評估並追蹤頸椎脊髓神經病變患者接受減壓手術後之功能性表現及站立姿勢控制能力，並確立何種功能性評估最能反映出減壓手術後站立姿勢控制變化。 研究設計：觀察性研究 研究方法：在實驗一中，參與者會被分成為脊髓病變組（63名受試者），神經根病變組（24名受試者）和健康對照組（19名受試者）。脊髓神經病變組和神經根病變組會進行日常功能性評估，其包括功能性問卷（頸部失能量表（NDI）、日本骨科學會頸椎脊隨病變評估問卷（JOACMEQ）之下肢功能分數、Nurick量表以及改良式日本骨科學會（JOA）量表之下肢運動功能障礙分數）和功能表現（腳踏測試、五次坐到站測試和10秒原地踏步測試）。再者，三組的參與者皆會以自然站姿及雙腳併攏站姿站立於力板上，並分別在睜眼和閉眼情況下紀錄其壓力中心之前後側和左右側位移。在實驗二中，參與者被分成脊髓病變組（53名受試者）和健康對照組（22名受試者）。脊髓病變組會在術前與術後3個月、術後6個月和術後1年進行日常功能性表現評估（包括NDI，JOACMEQ下肢功能和10秒步進測試）以及在睜眼和閉眼下站立於力板上的姿勢控制評估。而對照組僅需參與站立姿勢控制評估。 結果：在實驗一中，日常功能性測試中的JOACMEQ下肢功能分數與站立時壓力中心參數(center of pressure variables)之間的有顯著的一般相關性（r < 0.5，p < 0.05）。以Nurick量表分數進行嚴重程度分組的兩組脊髓病變組之壓力中心參數在閉眼站立的情況下有顯著性差異（p < 0.05）。在Nurick量表分數為“2或3”的脊髓病變組之壓力中心參數明顯地比神經根病變組和健康對照組高（p < 0.05）。在實驗二中，脊髓病變組的NDI分數（p = 0.036）和JOACMEQ之下肢功能分數（p = 0.036）在減壓手術後均有顯著地改善，而在睜眼自然站立時，在壓力中心的95％置信橢圓面積（p = 0.022）、平均速度（p = 0.019）、前後向範圍（p = 0.007）、前後向均方根距離（p = 0.023）等壓力中心參數在術後有顯著地改善。然而，在所有的情況下，脊髓病變組之壓力中心參數在手術前後均顯著地高於健康對照組（p < 0.05）。若將術前之測量結果設置為基準，術後三個時間點的效應值和標準化反應平均值皆在-0.49至0.03的範圍內。以受試者工作特徵（Receiver operating characteristic，ROC）曲線方法分析並以JOACMEQ之下肢功能部分的第一題分數為依據，只有在術後3個月的壓力中心之95％置信區橢圓形區域、前後側範圍、左右側範圍和左右側均方根距離（面積> 0.70 ）的最小臨床重要差異能被計算出來。 結論：Nurick量表適合被用於分類頸椎脊髓病變患者之姿勢不穩定的程度，Nurick分數較高之頸椎脊髓神經病變患者相比於神經根病變患者或健康對照組，其姿勢控制有較明顯地受損。此外，在減壓手術後，主觀功能性評估問卷的分數和睜眼時前後方向相關的壓力中心參數皆有顯著地進步，然而站立壓力中心參數卻不適合作為評估減壓手術後短期變化的工具。

Background: Cervical spondylotic myelopathy, which is a common degenerative disorder, may lead to impairment of upright postural control. The cervical decompression surgery is an invasive treatment for cervical myelopathy to remove the cord compression. However, there are few studies conducted on the relationship between functional outcomes and upright postural control, as well as effect of decompression surgery on upright postural control.

Purpose: (1) To determine the association between functional assessment with upright postural control of patients with myelopathy and to compare the upright postural control among patients with different severity of cervical myelopathy, patients with radiculopathy and healthy age-matched control; (2) To evaluate functional outcomes and upright postural control of patients with myelopathy after cervical decompression surgery and determine which statistical methods that reflect the clinically meaningful measure in upright postural control following cervical decompression surgery

Design: Observational study

Methods: In Experiment 1, participants were be recruited for myelopathy (63 subjects), radiculopathy (24 subjects) and age-matched control group (19 subjects). Only myelopathy and radiculopathy group were assessed by functional outcome measures, (i.e Neck Disability Index (NDI), Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ)-lower extremity function, Nurick scale, and modified Japanese Orthopaedic Association (JOA) scale-motor dysfunction of lower extremity (mJOA-MDLE)), and functional performances (i.e. foot taping test, five-times-sit-to-stand test and 10 second step test). Meanwhile, force platform was used to record the anteroposterior (AP) and mediolateral (ML) COP displacement of all participants in neutral and narrow stance with eyes-open and eyes-closed respectively. In Experiment 2, participants were recruited for myelopathy (53 subjects) and age-matched control group (22 subjects). The functional assessments, including NDI and JOACMEQ-lower extremity function and 10 second step test, were performed in myelopathy group at four phase: preoperative phase together with postoperative 3 months, 6 months and 1 year respectively. The standing balance assessment using force platform was performed in in myelopathy group at four phases and in age-matched control group only at recruitment day.

Results: In Experiment 1, the correlations between JOACMEQ-lower extremity function and COP variables were significantly fair (r < 0.5, p < 0.05). The COP variables of myelopathy group classify with Nurick score showed significant differences (p < 0.05) in all eyes-closed condition. The myelopathy group with Nurick score ‘2 or 3’ demonstrated significantly increased COP variables than radiculopathy and age-matched control group (p < 0.05). In Experiment 2, the NDI score (p = 0.036) and JOACMEQ-lower extremity function score of myelopathy group (p = 0.036) improved after decompression surgery. Significant improvement was shown in 95% confidence ellipse area (p = 0.022), mean velocity (p = 0.019), range-AP (p = 0.007), and RMS distance-AP (p = 0.023) in neutral stance with eyes-opened. However, the COP variables was significantly instable than healthy age-matched control (p < 0.05) before and after surgery in all standing condition. The effect size and standard response mean of all three postoperative phases ranged from -0.49 to 0.03 if the preoperative phase was set as baseline. Only minimally clinically important difference (MCID) for 95% confidence ellipse area, range-AP, range-ML, root mean square (RMS) distance ML (area > 0.7) in eyes-closed condition at postoperative 3 months were determine with first question of JOACMEQ-lower extremity function as anchor by receiver operating characteristic (ROC) curve analysis.

Conclusion: The Nurick scale may reflect severity of postural instability in patients with myelopathy. The myelopathy patients with higher Nurick score had obviously impaired upright postural control compared to patients with radiculopathy or healthy age-matched control. Besides, the subjective functional outcomes and COP variables in eyes-open condition significantly improved after decompression surgery. The COP variables were more suitable to reflect long-term change after decompression surgery.