早產兒與足月兒在坐姿下的頭部與軀幹的協調控制

Abstract

早產兒是罹患動作及姿勢控制障礙的高危險群。要成功的控制直立姿勢，個體必須協調控制身體各部位，以對抗重力的影響並符合特定情境的需求，如此才能維持身體在空間中的平衡。目前針對嬰幼兒如何發展在直立姿勢下控制身體協調的能力以及早產對姿勢協調控制的影響的相關研究十分有限，因此本研究的目的是要探討早產兒與健康足月兒於早期坐姿發展過程，其身體協調控制的改變以及觸覺對此協調控制的影響。受試嬰幼兒分為三組，包括12位早期早產兒(受孕週數<34週)、15位晚期早產兒(受孕週數≧34週且<37週)以及12位健康足月兒。所有嬰幼兒於開始獨坐至獨走後3個月期間接受長期追蹤，在七個發展時間點進行坐姿姿勢控制測試以及發展檢查。針對坐姿姿勢控制，受試嬰幼兒在二種本體感覺情境下接受靜態坐姿測試：右手扶在座椅扶手以及放手獨坐，使用超音波動作捕捉系統記錄嬰幼兒的頭部與軀幹在三維空間的動作，並採用交叉關係分析檢查頭與軀幹於前後與左右方向的動作在時間與空間上的協調關係。統計分析使用重複測試的三因子變異數分析比較3組嬰幼兒在7個發展時間點及2個本體感覺情境裡，其頭部與軀幹的動作在空間與時間上的協調關係。研究結果顯示頭與軀幹在前後方向的空間協調關係，在開始放手獨坐時的相關性皆顯著高於獨坐後1個月至放手走3個月。然而在左右方向則發現只有在開始放手獨坐的相關性顯著高於獨坐後2個月。在時間上的協調關係分析差則發現只有在開始放手獨坐時在左右方向上的絕對時間差顯著低於開始放手獨站。額外手觸覺會顯著降低在左右方向上頭部與軀幹動作之間的空間相關係數，但對於前後方向的協調則無明顯影響。比較三組嬰幼兒的協調控制，結果顯示早期早產兒相較於健康足月兒在左右方向顯示較弱的空間和時間上的頭與軀幹協同關係，而晚期早產兒與健康足月兒則無顯著差異。本研究結果顯示隨著坐姿經驗的增加，足月與早產嬰幼兒學會控制他們的坐姿會由低自由度的同步控制模式逐漸變成高自由度的非同步控制模式，且此坐姿控制發展在前後方向較在左右方向有明確的發展改變，並且額外的手觸覺可以增加足月與早產嬰幼兒探索身體在左右方向的協調。本研究結果顯示早期早產兒在早期的坐姿控制發展相較於健康足月兒有較成熟的高自由度的非同步控制模式，然而受限於樣本數較小且受試早產兒無罹患嚴重周產期併發症，本研究結果未必可以適用於所有早產兒，建議未來除增加受試者樣本數，還可探討早產兒周產期併發症對姿勢控制的影響。本研究結果建議嬰幼兒的早期坐姿控制發展主要發生在前後方向且會受到觸覺的影響，可作為臨床治療介入的參考。對於早期早產兒與晚期早產兒的姿勢控制及身體協調控制有長期追蹤的必要，以確定早期姿勢協調控制與其後續動作發展與姿勢協調控制的相關性。

Children born preterm are at risk for postural deficits and motor disabilities. To achieve successful postural control, one needs to manage the many degrees of freedom of the human body in the gravitational and sensory world. However, little is known about how infants develop to control the multi-segmented body in the upright posture and how such coordination of postural control may be affected by preterm birth. The purpose of this study was to investigate the upper body coordination in sitting posture of full-term and preterm infants and to examine the influence of additional somatosensory information on infants’ postural coordination. Three groups of infants were included in the study: early preterm (Pte, gestational age <34 weeks, n=12), late preterm (Ptl, gestational age≧34 weeks and <37 weeks, n=15), and full-term (Ft, n=12). Infants were longitudinally followed from sitting onset to 3months post-walking at 7 developmental epochs: sitting onset, 1- month post sitting, 2- month post sitting, standing alone, walking onset, 1-, and 3- month post walking. At each visit, the infant was tested for their quiet sitting posture in two sensory conditions: with or without the hand touching a contact surface. Three- dimensional displacements of the head and trunk were recorded using an ultrasonic motion capture system. Cross-correlation analyses were conducted to analyze the spatial and temporal coordination between head and trunk motions in the medial-lateral (ML) and anterior-posterior (AP) directions. Repeated measures ANOVAs were conducted to examine effects of postural experience, hand touch, and preterm birth on infants’ upper body coordination in sitting position. Our results revealed that, comparing to sitting onset, the spatial coupling between infants’ head and trunk decreased after 1 month post sitting and onward in the AP direction. For the ML direction, the un-coupled coordination occurred only at 2 months post-sitting (p<0.05). Comparing to sitting onset, the absolute time lag between head and trunk decreased at standing alone in the ML direction (p<0.05) but no difference between developmental epochs was found in the AP direction. Hand touch decreased the spatial coupling between head and trunk only in the ML direction (p<0.05). Pte, but not Ptl, infants demonstrated lower spatial and temporal head-trunk coupling in the ML direction compared to Ft infants (p<0.05). Our results suggest that, with increasing upright experience, infants’ upper body coordination in sitting posture changed from synchronous patterns toward articulated patterns. While early development of sitting postural control occurred more obvious in the AP direction than in ML direction, hand touch afforded infants to explore dynamics of body coordination in the ML direction. Furthermore, early preterm infants exhibited more mature patterns of body coordination than full-term infants did in controlling their sitting posture. Due to the small sample size and relatively healthy preterm sample, our results may not apply to all preterm infants. Our results that early development of sitting postural control occurs mostly in the AP direction and can be influenced by sensory inputs may help design intervention programs for infants and children with postural deficits. Long-term follow up of early and late preterm infants for their postural control and body coordination is necessary.