頸動脈超音波以預測頸動脈支架術後腦中風病人神經功能喪失之恢復

Abstract

腦中風目前是世界上第四大死因。在其所有的致病機轉中，頸動脈狹窄是最被公認的，因為它造成約30-35 % 的總腦中風人數。嚴重的頸動脈狹窄需用非侵犯性檢查(如頸動脈超音波-carotid ultrasound) >70 % 或用侵犯性檢查(如腦部血管射影術-digital subtraction angiography)>50 % 來確認。之所以要確認是因為嚴重的頸動脈狹窄是會造成初次及再次腦中風的機會大增且比常人高2-3 倍。此外在所有造成腦中風的因素中，年齡(age) 也是很重要。一般而言年齡越大，越有可能中風機會越大。目前用頸動脈支架術(carotid artery stenting)可以有效來預防初次及再次腦中風的機會。然而大型研究關於頸動脈支架術與病人年齡(age)術前預後因子的預測確無定論 。 臨床上醫師常會遇到需快速決定病人適不適合頸動脈支架術，此時若有一快速的決策機制(decision making)，對於病人及第一線醫師實是利多。此外因電腦斷層血管攝影術(computed tomographic angiography perfusion)須用顯影劑(contrast medium)來造影，有些病人(如腎功能不全-renal dysfunction) 不適合用此一醫學影像來追蹤頸動脈支架術後腦血流恢復情況。此時若能用頸動脈超音波(carotid ultrasound)來追蹤應可解決這個問題。阻力系數(Resistance index- RI) 是一個方便且可準確評估遠端血管阻力的數值，我們也探討其在頸動脈支架術之重要性及早期預測功能性預後的角色。

我們用回溯性方式收集病人資料。這些病人是第一次腦中風(first ever ischemic stroke)，總共有144位病人，他(她)們均有接受本院(彰化基督教醫院) 頸動脈支架術。他(她)們在頸動脈支架術前的臨床資料均有詳細計載。我們用巴氏量表(Barthel Index) 及改良Rankin量表(modified Rankin Scale-mRS) 在術前及12個 月後來評估病人預後(physical functionality)，進而把病人歸類為”進步”，”退步”及”保持原封不動”( improved, worsened, stationary)三大類。15個病人在術前及術後1個月有安排頸動脈超音波(carotid duplex)及電腦斷層血管攝影術(computed tomograpic angiography perfusion scanning )及收集了詳細資料。67個病人在術前及術後1個月有頸動脈超音波(carotid ultrasound)的資料。以上病人在術前的臨床可變量( clinical variables)均用SPSS Version 16.0 來作分析統計。

研究結果顯示頸動脈支架術可以使大部份病人受益且與年齡(age)無關。腦血容量的比值(ratio of cerebral blood volume)，巴氏量表(Barthel Index)，及高靈敏度C 反應蛋白( high sensititvity C reactive protein (hsCRP)) 可以有效預測病人預後。在我們決策機制(decision making )的研究中我利們用卡方自動交互檢視法(Chi-square automatic interaction detector-CHAID)及有限狀態機(finite-state machine-FSM)的研究方法，我們發現低密度脂蛋白(low-density lipoprotein-LDL)，‎痛風性關節炎(gouty arthritis)及同側頸總動脈阻力系數(ipsilateral common carotid artery resistance index- RI)可以給第一線臨床醫師快速的決斷及臨床上有用的資訊。此外我們也發現頸動脈超音波(carotid ultrasound)可取代電腦斷層血管攝影術(computed tomograpic angiography perfusion)的角色。利用術前及術後對側‎頸總動脈及同側內頸動脈阻力系數(contralateral common carotid artery (CCA)and ipsilateral internal carotid artery (ICA) RI)的變化我們可早期預估病人術後情況及真實觀察腦內外血流變化。

Stroke is the fourth leading cause of death worldwide. Among its various etiologies, carotid stenosis is the most well observed because it accounts for 30 to 35 percent of total ischemic strokes. Severe carotid stenosis with major lumen obsruction, which should be confirmed by non-invasive extracranial colour coded carotid duplex of >70 % lumen reduction and/or invasive catheter-based imaging study of >50 % vessel narrowing before treatment, can lead to doubles or triples of the risk in first-time ischemic stroke and its recurrence. Among various stroke contributors, age is the most important risk factor as most stroke patients, in general, are elderly in nature. It is also well-recognized that prompt management of carotid artery stenosis with stenting can prevent stroke or recurrent stroke. However, associations between peri-procedural carotid ultrasound parameters (particularly resistance index(RI)), baseline characteristics and post-treatment functional capabilities in first time elderly stroke patients have not been comprehensively investigated to date. In clinical practice, first-line medical personnel often encoutered scenarios that required quick decision-making as to suitabilty of carotid stenting procedure of various baseline functionality. Moreover, some stroke patients already had imparied renal function, which could discourage the follow-up computed tomographic angiography perfusion (CTA/P) exam, attempting to assess the cerebral reperfusion status after carotid stenting procedure. We, therefore, investigate the importance of resistance index (RI) of the carotid ultrasound, hoping to replace the role of CTA/P.

We retrospectively examined the medical records of all patients who underwent carotid artery stenting for ischemic stroke during the period from January 2010 to November 2014 at the angiography laboratory of the department of neuro-imaging, Changhua Christian Hospital, Changhua. In total 144 consecutive patients with first-ever ischemic stroke that underwent carotid artery stenting (CAS) were included. Clinical data were obtained by review of medical records and cross-checked by electronic version of Changhua Christian Hospital 2000 computer based system. The Barthel Index (BI) and modfied Rankin Scale (mRS) were used to assess disability before stenting and at 12-month follow-up. Pre- and post-stenting mRS scores were compared to determine patient outcomes and classified as improved, stationary or deteriorated. 15 patients were conducted with CTA/P and carotid duplex exams simutaneously before and one month after stenting procedure. Carotid ultrasound was conducted before stenting and four weeks after the procedure of 67 patients. Following classification, comparison of groups according to post-stenting mRS score was conducted using all available recorded variables. All of the studied parameters were analyzed by SPSS Version 16.0.

Our findings indicate that in our elderly patient series, carotid artery stenting may benefit a significant proportion of carotid stenotic patients regardless of age. Ratio of cerebral blood volume, Barthel Index (BI), and admission high sensititvity C reactive protein (hsCRP) could serve as important predictors of mRS improvement and may facilitate differentiation of patients at baseline. In our decision-making model, we highlight the admission low density lipoprotein(LDL), gouty arthritis, and ipsilateral common carotid artery (CCA) resistance index (RI) are strongly associated with long term functional outcomes with utilization of chi-squared automatic interaction detection system (CHAID) and finite-state machine (FSM) methods. Moreover, it reveals that carotid duplex can potentially replace the role of CTA/P, as well as early prediction of patients’ functional outcomes and genuinely reflecting of cerebrovascular hemodynamics after stenting treatment with contralateral common carotid artery (CCA) and ipsilateral internal carotid artery (ICA) RI.