腰椎狹窄症對姿態平衡的影響

Abstract

腰椎狹窄症是老年族群中常見的脊椎疾病。由於脊椎骨骼、韌帶及肌肉退化，再加上神經壓迫，這些因素可能導致本體感覺及動作控制功能異常。過去的研究指出腰椎狹窄症患者會有姿態平衡功能異常，然而此平衡功能異常與臨床表現及影像學檢查結果之間的關係仍不清楚。因此，目前對於腰椎狹窄症的診斷及治療決策主要依據臨床表現及影像學檢查結果，較少參考相關的生理檢查。 人體在維持姿態平衡上仰賴視覺、平衡覺、及本體感覺的多方訊息，經由複雜的神經系統整合及調控。泡綿重心動搖儀可評估整體平衡功能，並透過不同檢查模式，分析視覺、平衡覺、及本體感覺的影響程度，目前常規醫療中已使用泡綿重心動搖儀檢測患者的姿態控制能力。然而，此儀器不適合攜帶且輸出項目固定，限制了其用於腰椎狹窄症患者之平衡功能的相關研究。 為克服傳統重心動搖儀的限制，本研究初期以發展一個適合攜帶、量測精準、且可擴充輸出項目的姿態平衡檢測系統為目標。此外，亦將探討腰椎狹窄症的臨床表現及影像學檢查結果與姿態平衡能力之間的關係。 本研究所開發的姿態平衡檢測系統以自行編寫的程式透過藍芽技術連接任天堂公司的Wii平衡板，擷取其內部類比數位轉換器的原始訊號以得到各荷重感應元之受力大小，取得人體站立時重心投影在二維平面的座標，後續用以計算姿態平衡的相關指標。與目前市面上臨床使用的泡綿重心動搖儀作性能比較測試中，召募20位年輕的周邊型前庭系統功能失調病患以及20位經年齡性別配對的健康成年人進行系統可靠度測試；另外，亦招募50位年長的周邊型前庭系統功能失調病患以探討本系統在判別跌倒病史上的效度。 與臨床上常規使用的系統相比，本研究以Wii平衡板為基礎所開發的系統所測得的靜止站立動搖面積較小 (p < 0.01)，但系統的可靠度達到0.67–0.87，再測信度達到0.53–0.88。此外，若搭配軟泡綿墊使用，於開眼及閉眼狀態下對是否有跌倒病史的判斷，ROC曲線分析模型之area under the curve (AUC)分別達到0.88及0.83 (p < 0.001)，而動搖面積的閾值為1.03及3.09平方公分。 為探討腰椎狹窄症的臨床表現及影像學檢查結果與姿態平衡能力之間的關係，招募了47位年紀介於50至85歲的病患。每位病患均接受詳細的病史紀錄、理學檢查、脊椎的X光檢查、核磁共振檢查、以及泡綿重心動搖儀檢查。另外，亦招募47位經年齡性別配對的健康成年人接受泡綿重心動搖儀檢查作為對照組。 與健康對照組相比，腰椎狹窄症患者的靜止站立動搖面積在重心動搖儀檢查的四個情境中皆顯著增加 (p < 0.001)。進一步利用多元迴歸分析發現，年紀大、較差的行走耐受度、以及在核磁共振檢查中有L2/3節段的神經壓迫與重心動搖儀檢查的指標顯著相關 (p < 0.05)；相反的，病患主觀的不適、失能程度、以及X光檢查的結果，與重心動搖儀檢查檢果無顯著相關 (p > 0.05)。 因此，脊椎狹窄症的患者即使症狀輕微，仍可能有姿態平衡的問題；而患者的姿態平衡功能與核磁共振檢查結果顯著相關。除了詳細的病史詢問、理學檢查、以及影像學檢查之外，加上重心動搖儀檢查或許可以對患者有更完整的評估。此檢查花費時間短、費用低廉，可考慮作為評估腰椎狹窄症患者的常規檢查之一。

Lumbar spinal stenosis (LSS) is a common cause of discomfort and disability. The current diagnosis and treatment decision-making mainly depend on clinical symptoms and image findings. Although functional impairment in patients with LSS have been reported, the relationship between balance assessment and clinical findings in patients with LSS remains less investigated. Multiple sensorimotor networks, such as visual, vestibular, somatosensory, and cerebellum systems, integrate with each other to maintain postural control. Clinically, foam posturography has been applied to evaluate standing balance, but it is costly and lacks portability, which makes it unsuitable for daily clinical use. Hence, this study first developed a portable posturography system to meet the requirement of daily clinical use, and investigated its reliability and validity. Then, we correlated clinical symptoms, radiographic parameters, and findings in MR imaging with posturographic results in patients with lumbar spinal stenosis. A custom-written software application was developed to link a computer to the Nintendo Wii balance board (WBB) via Bluetooth connection, and native data from the analog-to-digital converter of the WBB were retrieved to obtain the force applied to each load cell. The center of pressure was acquired, which was then compared with that obtained from commercially available foam posturography (FP). Forty younger adults including 20 patients with peripheral vestibular disorders as well as 20 healthy controls, and 50 older patients with peripheral vestibular disorders were enrolled. All subjects underwent postural balance testing using the WBB system (WBBS) and FP system (FPS) in a randomized order. For the inter-system reliability, although the WBSS obtained a significantly smaller mean sway area than the FPS (p < 0.01), both systems revealed adequate to excellent reliability with an intraclass correlation coefficient (ICC) of 0.67–0.87. The WBBS showed adequate to excellent test-retest reliability (ICC: 0.53–0.88). For the validity, the respective cutoff sway areas were 1.03 cm2 and 3.09 cm2 under Conditions C and D via the WBBS for discriminating the fallers from non-fallers, with the area under the curve (AUC) in receiver operating characteristic (ROC) analysis being 0.88 and 0.83 respectively (p < 0.001). To correlate clinical and radiological assessment with functional assessment in LSS patients, 47 LSS patients aged 50–85 years were enrolled. All patients received subjective outcome measures first, followed by plain radiography of lumbosacral spine and whole spine, MR imaging, and foam posturography under four conditions. Then, these results were analyzed using stepwise multiple regression analysis. Another 47 age- and sex-matched healthy controls also underwent foam posturography for comparison. The LSS group revealed significant increases in the sway area of foam posturography than the control group regardless of various conditions (p < 0.001). Advanced age, poor walking endurance, and neural compression at the L2/3 level on MR images were significantly correlated with the characteristic parameters of foam posturography (p<0.05). In contrast, subjectively reported pain and plain radiography did not correlate with posturographic results (p>0.05). In conclusion, patients with LSS who exhibit less severe symptoms do not ensure normal postural balance. Functional assessment (foam posturography) on postural balance significantly correlated with radiological assessment (MR imaging) in LSS patients. The use of foam posturography may help assess postural control in LSS patients. It takes a short time and costs less, and would be practical to make this a routine examination in LSS patients.