後頂葉皮質區受損之中風病患於側向反應性姿勢控制能力之缺損以及給予提示對其控制能力之影響

Abstract

背景與目的：反應性姿勢控制能力 (reactive postural control ability) 取決於感覺訊息的整合以及動作與姿勢的協調。近年研究發現輸入的感覺訊息會經大腦後頂葉皮質區 (posterior parietal cortex, PPC) 整合與注意後轉換為動作訊息，再傳至前動作皮質區 (premotor cortex)，以利動作計畫與動作執行。因此可推測後頂葉皮質區損傷可能導致注意與姿勢控制能力的缺損。故本研究目的為探討後頂葉皮質區損傷是否造成中風病患站姿平衡能力缺損以及給予事先提示對患者的影響。法：9位大腦受損區包含後頂葉皮質區之中風病患 (PPC+組, 平均年齡= 60.8±13.9歲) 與9位大腦受損區不包含後頂葉皮質區之中風病患 (PPC-組, 平均年齡= 69.9±10.3歲) 參與本研究。另有9位年齡相符之健康受試者參與，為控制組 (Healthy組, 平均年齡= 67.9±13.7歲)。所有參與者須在受到由多方向牽拉儀 (Advance Instrument, Inc., Taipei, Taiwan) 產生之側向牽拉干擾 (lateral perturbation) 後，於儘量不移動雙腳的情況下，維持站立平衡。本實驗包含無提示與提示情境各6次牽拉測試 (trials)。在提示情境下，研究者於牽拉干擾前給予聽覺提示，使參與者可事先知道干擾方向。本實驗中分析反應姿勢肌活化模式、最早活化之反應姿勢肌潛伏時間 (onset latency)、施力反應時間 (reaction time)、到達施力峰值時間 (time-to-peak phase duration) 以及側向衝量 (total force impulse)。果：在無提示情境下，健康受試者以與牽拉方向同側邊之臀中肌 (gluteus medius) 與腓長肌 (peroneal longus) 為主要反應肌 (活化率分別為88.5%與73.1%)，且大多以臀中肌最早反應 (反應姿勢肌潛伏時間為129.1毫秒)。兩組中風受試者受到向健側邊的牽拉干擾時反應模式與健康受試者相似；但受到向患側邊的牽拉干擾時，除患側之臀中肌與腓長肌外，健側臀中肌亦為主要反應姿勢肌之一。尤其在PPC+組受到向患側邊的牽拉干擾時，健側臀中肌之活化率 (40.0%) 趨近於患側之臀中肌 (56.0%) 與腓長肌 (48.0%)，且為最早活化之姿勢反應肌 (反應姿勢肌潛伏時間為167.0毫秒)。至於反應姿勢肌潛伏時間分析結果發現，在無提示情境下受到向患側的牽拉干擾，PPC+組 (167.0毫秒) 的時間顯著長於Healthy (129.1毫秒) 與PPC- (136.3毫秒) 組 (Healthy組與PPC+組: p = .008; PPC-組與PPC+組: p = .039)，但Healthy與PPC-組之間無顯著差異。此外，PPC+組於受到向患側干擾時之反應姿勢肌潛伏時間較受到向健側干擾時的 (124.8毫秒) 長 (p = .001)。而無論牽拉方向為何，三組的施力反應時間與到達施力峰值時間皆無差異 (p > .05)。側向衝量分析結果顯示，當受到向患側的牽拉干擾，兩組中風病患產生的衝量 (PPC-: 1019.4 體重百分比*毫秒; PPC+: 1152.4體重百分比*毫秒) 較健康成人 (1504.0體重百分比*毫秒) 小 (Healthy組與PPC-組: p = .004; Healthy組與PPC+組: p = .028)。給予提示後，PPC+組於受到向患側邊干擾時患側臀中肌的活化率顯著增加 (活化率為80.8%)，且反應姿勢肌活化模式變成與健康成人的相似。而提示對於三組受試者之反應姿勢肌潛伏時間、到達施力峰值時間與側向衝量並無顯著影響 (p > .05)，但可以加快健康成人的施力反應時間 (p = .035)論與結論：PPC+組的站立反應性姿勢控制能力較Healthy與PPC-組差，可能原因為感覺動作訊息轉換能力 (sensory-motor transformation) 缺損導致。此外，本研究中發現聽覺提示可改善後頂葉皮質區受損之中風病患姿勢肌反應策略，但並未改善其反應姿勢肌之潛伏時間及與時間相關之力學上的反應能力。顯示聽覺提示可能可提高後頂葉皮質區受損病患對輸入之感覺訊息的注意力、改善感覺動作訊息轉換能力或有助於計畫動作輸出之次序或相關姿勢肌，因而改善其反應策略。反應肌潛伏時間則依賴感覺輸入之快慢與感覺動作訊息轉換之速率，而與時間相關之力學表現除上述兩項外亦取決於反應肌產生力量之速率。後頂葉皮質區受損之中風病患可能並未因接收聽覺提示而增進其感覺動作整合與反應肌產生力量之速率，所以其姿勢反應上並未較快。未來研究仍須進一步探討其他感覺提示 (如視覺或觸覺) 對後頂葉皮質區受損之中風病患反應性姿勢控制能力之影響。

Background and Purpose─ Reactive postural control ability depends upon the integration of all sensory inputs and descending motor drives. Recent studies suggest that all sensory inputs are integrated and attended, and then are transformed into motor commands (sensory-motor transformation) in the posterior parietal cortex (PPC) for planning and executing movements. Therefore, it is expected that lesions over the PPC would cause deficits in attention and motor control. However, little empirical evidence has been provided regarding standing balance deficits and effects of precues in patients with the PPC lesion. ethods─ Nine patients with stroke (mean age= 60.8±13.9yrs) with lesions involving the PPC region (PPC+ group), nine patients with stroke (mean age= 69.9±10.3yrs) with lesions not involving the PPC region (PPC- group) and nine healthy, age-matched adults (mean age= 67.9±13.7yrs) participated in this study (healthy group).ll participants were asked to maintain standing balance without stepping, if possible, after experiencing lateral pulling perturbation in the no-cue and cue conditions. There were 6 trials each in the no-cue and cue conditions. An auditory precue regarding the pulling direction was given to the participants in the cue condition. Postural muscle activation patterns, the earliest muscle onset latency (OLEarliest), reaction time (RT) of lateral force, time-to-peak phase duration (PDTTP) and total force impulse (IMPTotal) were analyzed to investigate the performance of each participant.esults─ In the no-cue condition, the gluteus medius (GM) and peroneal longus (PL) muscles of the leg on the side ipsilateral to the pulling perturbation direction (GMIpsi and PLIpsi) were the predominant muscles generating postural responses in the healthy group (firing rate: 88.5% and 73.1%, respectively). Similar results were also found when both stroke groups responded to perturbation towards the unaffected side. When responding to perturbation towards the affected side, the GM of the leg contralateral to the perturbation direction (GMContra) became one of the predominant muscles. Half subjects of the PPC- relied on co-contraction of GMIpsi and GMContra for reactive responses. And one-third of the subjects in the PPC+ groups relied on GMContra in response to perturbation. Compared to the healthy (OLEarliest = 129.1 ms) and PPC- (OLEarliest = 136.3 ms) groups, the PPC+ group showed longer OLEarliest (167.0 ms) while responding to perturbation towards the affected side (healthy vs. PPC+: p = .008; PPC- vs. PPC+: p = .039), but there was no difference in OLEarliest between the healthy and PPC- groups. In addition, the PPC+ group, but not the PPC- group, showed significantly longer OLEarliest when responding to perturbation towards the affected side (167.0 ms) than unaffected side (124.8 ms) (p = .001). For the RT and PDTTP, there was no group, neither direction, main effect. For the IMPTotal, both stroke groups generated smaller IMPTotal than the healthy group after a pull to the affected side (healthy vs. PPC-: p = .004; healthy vs. PPC+: p = .028). After cuing, the muscle activation patterns of the PPC+ group in response to a pull to the affected side became similar to those of the healthy group, and the healthy group showed shorter RT (p = .035). There were no significant effects of the auditory cue on OLEarliest, PDTTP and IMPTotal (p > .05) in this study.iscussion and Conclusions─ The PPC+ group showed the poorest reactive postural responses to lateral pulls among these three groups, which may be due to their deficits of sensory-motor transformation. Provision of a prior auditory cue seems to improve the construction or selection of proper postural strategy, but not the time needed to generate sufficient muscle or force responses, in patients with the PPC lesion. These temporal parameters may be determined by how fast the patients could process and integrate all sensory information, how fast they could perform the sensory-motor transformation and how fast they could generate force necessary for postural responses. Our auditory cue did not seem to improve the rate of information processing, the sensory-motor transformation and force generation of the PPC+ subjects. Further studies are required to investigate whether precue of other forms, such as visual or tactile cues, would effectively improve reactive postural responses of these patients.