Mechanical thrombectomy in acute stroke for superior limb of the fenestration of the middle cerebral artery

Fenestration of the middle cerebral artery (MCA) is a rare anatomic variant, and lenticulostriate arteries (LSAs) often arise from the superior limb of the fenestrated segment. A case of acute occlusion of the superior limb of a fenestrated MCA that successfully underwent mechanical thrombectomy is presented. Digital subtraction angiography performed for a 73-year-old man with acute left hemiparesis showed poor visualization of the upper half of the right M1 segment with maintenance of antegrade peripheral circulation of the MCA territory, and mechanical thrombectomy was successfully performed using a stent retriever with intravenous thrombolysis. After restoration of the MCA, the vascular variant of a fenestrated MCA was found. Clinicians must consider the possibility of acute occlusion of a fenestrated MCA before endovascular thrombectomy. Restoration of acute occlusion of the upper limb of a fenestrated MCA can avoid LSA territory infarction.     

左室收缩功能障碍与6~24 h内接受机械取栓的急性缺血性脑卒中患者不良预后相关

目的探讨以左室射血分数（LVEF）测量的左室收缩功能障碍（LVSD）与6~24 h内接受机械取栓治疗的前循环大血管闭塞型急性缺血性脑卒中（AIS）患者90 d预后的相关性。 方法回顾性分析2018年1月至2021年1月在发病后6~24 h内于我院接受机械取栓治疗的急性缺血性脑卒中患者资料。根据国际准则采用Simpson双平面法在二维超声心动图上评估LVEF,LVEF < 50%即定义为LVSD。90 d改良Rankin量表（mRS）评分3~6分定义为不良功能预后。采用单因素和多因素Logistic回归分析明确LVSD与90 d不良预后的相关性。 结果共计纳入了107例患者,其中26例（24.3%）术后出现了LVSD。多因素分析显示,LVSD（OR = 4.206,95%CI：1.357~13.035,P = 0.013）、美国国立卫生研究院卒中量表（NIHSS）基线评分高（OR = 1.234,95%CI：1.114~1.367,P < 0.001）、再灌注不良（mTICI 0~2a） （OR = 4.388,95%CI：1.373~14.023,P = 0.013）是90 d不良功能预后的独立危险因素。年龄（OR = 1.081,95%CI：1.005~1.161,P = 0.035）、LVSD （OR = 3.783,95%CI：1.029~13.911,P = 0.045）、美国国立卫生研究院卒中量表（NIHSS）基线评分高（OR = 1.109,95%CI：1.026~1.198,P = 0.009）是90 d死亡率的独立危险因素。 结论LVSD与6~24 h接受机械取栓治疗的急性缺血性脑卒中患者90 d不良预后独立相关。     

后循环急性缺血性脑卒中患者经机械取栓完全复流后不良预后的影响因素分析

目的探索后循环急性缺血性脑卒中（PCS）患者经机械取栓并完全恢复前向血流后部分患者临床预后仍然不佳的影响因素。 方法连续纳入2017年1月至2020年9月于我院接受机械取栓治疗的PCS患者并进行回顾性分析。闭塞血管完全恢复前向血流定义为改良脑梗死溶栓血流分级（mTICI）达3级。90 d改良Rankin评分（mRS）> 2分则被定义为预后不良。将患者基线资料、治疗相关指标纳入多因素分析,并采用受试者工作特征曲线（ROC）来确定最佳界值。 结果共纳入39例经机械取栓治疗后完全恢复前向血流（mTICI 3级）的PCS患者。其中,预后不良患者共20例（51.3%）。采用逐步Logistic回归分析显示,入院时美国国立卫生研究院卒中量表（NIHSS）评分较高（OR = 1.21,95%CI = 1.037~1.414,P = 0.016）、后交通动脉（PcomA）未开放（OR = 0.052,95%CI = 0.005~0.557,P = 0.014）为90 d不良预后的独立预测因素。基于ROC曲线分析显示,入院时NIHSS评分曲线下面积为0.762,截断值为20分,敏感度为70.0%,特异度为84.2%。 结论入院时NIHSS评分高、后交通动脉未开放,是后循环急性缺血性脑卒中患者接受机械取栓治疗并完全恢复前向血流后临床预后仍不佳的相关因素。     

支架取栓与动脉溶栓治疗急性缺血性脑卒中比较

目的 探讨Solitaire AB支架取栓联合动脉内溶栓治疗急性缺血性脑卒中(AIS)的效果及安全性.方法 选取2010年6月至2015年6月采用动脉内治疗AIS患者60例,其中30例接受微导管置于阻塞血管近端或阻塞血管血栓内的尿激酶溶栓治疗(单纯溶栓组),30例接受Solitaire AB支架取栓联合微导管注入尿激酶溶栓治疗(支架取栓组).观察两组治疗前后美国国立卫生研究院卒中量表(NIHSS)评分、术后血管再通率、颅内出血率、90 d内病死率及90 d后改良Rankin量表(mRS)评分.结果 支架取栓组和单纯溶栓组治疗前、治疗后14 d NIHSS评分分别为(21.89±5.62)分、(7.78±2.36)分(P＜0.001)和(18.40±6.59)分、(7.00±2.28)分(P＜0.001),组间差异均无统计学意义(P＞0.05);血管再通率分别为86.67％ (26/30)、63.33％(19/30)(X2=4.356,P＜0.05);颅内出血发生率分别为10.00％(3/30)、13.33％ (4/30)(x2=0.162,P＞0.05);90 d内病死率分别为13.33％ (4/30)、16.67％(5/30) (x2=0.131,P＞0.05);术后90 d预后良好(mRS评分＜2)分别为66.67％ (20/30)、36.67％ (11/30)(x2=5.406,P＜0.05).结论 Solitaire AB支架取栓联合动脉内溶栓治疗大血管闭塞的AIS后血管再通率及90 d预后均显著优于单纯动脉内溶栓治疗,但远期疗效及安全性尚需更多病例的多中心前瞻性随机对照研究验证.     

机械取栓治疗伴椎基底动脉闭塞的轻型卒中2例分析

目的：探讨机械取栓治疗伴椎基底动脉闭塞的后循环轻型卒中的有效性及安全性。 方法：通过对2例伴椎基底动脉闭塞轻型卒中患者进行机械取栓治疗,并引用文献进行分析,探讨该治疗方法的有效性及安全性。 结果：2例合并椎基底动脉闭塞的轻型卒中通过机械取栓治疗均取得良好的效果,未出现明显的并发症。 结论：对合并椎基底动脉闭塞的轻型卒中进行机械取栓治疗安全有效;治疗过程中准确评估血栓长度及部位,采取综合措施再通血管同时防止血栓远端脱落是最关键的治疗要素。     

Mechanical thrombectomy in acute ischaemic stroke patients with pre-interventional intracranial haemorrhage following intravenous thrombolysis

BackgroundData on outcome of endovascular treatment in patients with acute ischaemic stroke due to large vessel occlusion suffering from intravenous thrombolysis-associated intracranial haemorrhage prior to mechanical thrombectomy remain scarce. Addressing this subject, we report our multicentre experience.MethodsA retrospective analysis of consecutive acute ischaemic stroke patients treated with mechanical thrombectomy due to large vessel occlusion despite the pre-interventional occurrence of intravenous thrombolysis-associated intracranial haemorrhage was performed at five tertiary care centres between January 2010–September 2020. Baseline demographics, aetiology of stroke and intracranial haemorrhage, angiographic outcome assessed by the Thrombolysis in Cerebral Infarction score and clinical outcome evaluated by the modified Rankin Scale at 90 days were recorded.ResultsIn total, six patients were included in the study. Five individuals demonstrated cerebral intraparenchymal haemorrhage on pre-interventional imaging; in one patient additional subdural haematoma was observed and one patient suffered from isolated subarachnoid haemorrhage. All patients except one were treated by the ‘drip-and-ship’ paradigm. Successful reperfusion was achieved in 4/6 (67%) individuals. In 5/6 (83%) patients, the pre-interventional intracranial haemorrhage had aggravated in post-interventional computed tomography with space-occupying effect. Overall, five patients had died during the hospital stay. The clinical outcome of the survivor was modified Rankin Scale=4 at 90 days follow-up.ConclusionMechanical thrombectomy in patients with intravenous thrombolysis-associated intracranial haemorrhage is technically feasible. The clinical outcome of this subgroup of stroke patients, however, appears to be devastating with high mortality and only carefully selected patients might benefit from endovascular treatment.     

急性缺血性卒中Solitaire AB支架取栓术后颅内出血并发症分析

目的 探讨急性缺血性卒中(AIS)患者接受Solitaire AB支架取栓术后颅内出血并发症的影响因素.方法 收集2015年6月至2016年10月采用Solitaire AB支架取栓术治疗的32例AIS患者临床资料.分析 取栓术后发生颅内出血性转化(HT)并发症患者基本资料,并与国内外相关研究进行对比分析.结果32例AIS患者取栓手术均成功,术后病死率为9.4％(3/32).3例术后发生症状性颅内HT,其中1例为前循环动脉闭塞,2例为后循环动脉闭塞,HT发生率为9.4％(3/32).2例保守治疗,1例行经脑室钻孔外引流并植入储液囊,最终2例因HT死亡,1例经保守治疗恢复良好.HT死亡患者占所有死亡患者比例为2/3.结论 颅内HT是AIS取栓手术致命性并发症.临床实践中应严格把握取栓手术适应证,术中精细操作,规范围术期管理,以降低出血并发症发生率.     

机械取栓在急性血栓性脑卒中中的应用

急性血栓性脑卒中是严重威胁人类健康的常见病,其治疗方法主要有静脉溶栓、动脉溶栓和机械取栓.近年来,对于不适合静脉溶栓或静脉溶栓失败的患者,机械取栓由于其所取得的较好的效果受到越来越多的关注,现就其有关方面予以综述.     

机械祛栓治疗急性肺动脉栓塞的实验研究

目的实验性比较经导管机械祛栓、经导管肺动脉内局部溶栓和经导管机械祛栓联合局部溶栓治疗急性肺动脉栓塞疗效和安全性。方法28只杂种犬经数字法随机分为4组,机械祛栓治疗组、局部溶栓治疗组、机械祛栓联合局部溶栓治疗组和对照组(CTL组)各7只。用犬的自体血栓建立急性肺动脉栓塞模型,分别采用经导管予机械祛栓(helix thrombectomy device,HTD)、尿激酶(UK)局部溶栓、机械祛栓联合尿激酶及生理盐水治疗。监测肺动脉平均压(PAMP)、主动脉收缩压(SBP)、血气及肺动脉造影情况。术后取动物肺组织行病理检查。结果在各组中,治疗后PAMP在30min时,CTL组为(33.5±3.38)mm Hg(1mm Hg=0.133kPa),UK组为(29.00±3.96)mm Hg,HTD组为(29.39±3.17)mm Hg,HTD+UK组为(25.24±3.04)mm Hg(q=6.88,P=0.002);60min时,CTL组为(33.19±3.54)mm Hg,UK组为(28.79±3.96)mm Hg,HTD组为(24.44±3.70)mm Hg,HTD+UK组为(23.57±4.57)mm Hg(q=8.73,P=0.000);120min时,CTL组为(31.50±3.75)mm Hg,UK组为(26.43±4.04)mm Hg,HTD组为(22.00±3.62)mm Hg,HTD+UK组为(17.86±3.26)mm Hg(q=17.78,P=0.000)。治疗后30、60和120min与对照组同时相的PAMP相比均明显降低,差异有统计学意义(P<0.05)。HTD组于治疗后120min与UK组同时相PAMP相比差异有统计学意义(P<0.05)。HTD+UK组治疗后30min和120min较UK组和HTD组同时相的PAMP降低更为明显(P<0.05);治疗60min与UK组差异有统计学意义(P<0.05)。治疗后的肺动脉造影表现为阻塞的肺动脉血流完全或不完全再通;充盈缺损减小;相应肺组织血流完全或不完全恢复。病理检查:(1)对照组:所见栓塞部位与肺动脉造影结果一致。光学显微镜下,肺动脉血管内可见血栓,肺组织大片出血灶,部分肺泡腔内大量红细胞。(2)治疗组:肺出血轻,肺泡腔内少量红细胞。HTD操作的相应肺动脉内膜轻微损伤。结论HTD消融器祛栓联合局部溶栓的疗效明显优于单独经导管肺动脉内局部溶栓或HTD消融器祛栓治疗,具较高的安全性。     

前循环串行病变的急诊介入治疗

目的分析机械取栓治疗前循环串行病变的疗效。 方法9例前循环串行病变的患者进行取栓治疗,对合并颈动脉重度狭窄的患者辅以球囊成形或支架成形术。回顾性分析围手术期血管开通率及手术并发症情况。随访3个月,应用改良Rankin评分（mRS）进行评价临床疗效。 结果腔内治疗后即刻再通率89%,症状性脑出血11%,90 d良好功能预后（mRS 0～2）33%,90 d随访死亡率11%。 结论对前循环串行病变取栓并近段颈动脉病变成形术是安全有效的。     

Delayed reperfusion therapy for ischemic stroke tandem occlusion with subsequent secondary prophylaxis of cerebral ischemic events: A case report and literature review

Mechanical thrombectomy is currently the gold standard treatment of large vessel occlusions, especially in anterior circulation acute ischemic stroke. At the same time, the problem of tandem occlusions seems especially important since most of the major clinical mechanical thrombectomy studies did not specifically evaluate patients with concomitant extracranial occlusions or critical stenoses.To date, there is no universally accepted optimal treatment strategy for such tandem lesions in acute ischemic stroke: it remains unclear which lesion – intracranial or extracranial – should be treated first. The selected reperfusion method should be based on the patients’ individual characteristics, data from non-invasive radiologic studies, and the stroke team experience.We present a case of successful reperfusion therapy of acute tandem occlusion of the right internal carotid artery, followed by contralateral carotid artery stenting in a patient with stenosing extracranial atherosclerosis.     

急性后循环缺血机械取栓研究现状与进展

【摘要】　脑卒中已成为世界上第二大致死性疾病和最常见致残性疾病,其中约85%为缺血性脑卒中。开通闭塞血管是急性缺血性脑卒中关键治疗方法,主要包括静脉溶栓、动脉溶栓和机械取栓(MT)。随着溶取栓技术和器械不断发展,静脉溶栓联合血管内取栓桥接治疗逐渐成为急性颅内大血管闭塞首选治疗方法。MT治疗前循环缺血性脑卒中的安全性和有效性已有多项临床研究证实,MT也纳入相关指南。然而,目前尚缺乏后循环缺血性脑卒中血管内治疗的随机对照临床研究数据,以确定统一标准指导。该文就急性后循环缺血性脑卒中MT器械发展、影像学评估、预后、并发症及补救措施等研究现状与进展作一综述。     

rt-PA溶栓治疗急性缺血性脑卒中临床效果及影响因素分析

目的探讨重组组织型纤溶酶原激活剂(rt-PA)溶栓治疗急性缺血性脑卒中(AIS)的临床效果及影响因素。方法回顾性分析2016年1-12月我院收治的48例AIS患者的临床资料。所有患者均于发病6 h内行rt-PA溶栓治疗。应用动脉闭塞评分评价溶栓效果,根据溶栓效果将患者分为有效组(A组)与无效组(B组)。比较两组患者血糖、收缩压、甲状腺激素T3水平、发病至治疗时间(OTT)、心源性卒中例数及美国国立卫生研究院卒中量表(NIHSS)评分。多因素Logistic回归分析rt-PA溶栓治疗效果的影响因素。结果 A组患者血糖、收缩压、甲状腺激素T3水平、OTT及NIHSS评分低于B组,差异均有统计学意义(P<0.05);心源性卒中比例高于B组,差异有统计学意义(P<0.05)。NIHSS评分、OTT与溶栓效果呈负相关(r值分别为-0.076与-0.083,P均<0.05);甲状腺激素T3水平与溶栓效果呈正相关(r=0.037,P<0.05)。A组患者治疗后24 h神经功能恢复良好比例及7 d转归良好比例均高于B组,差异有统计学意义(P<0.05)。结论 NIHSS评分、甲状腺激素T3水平及OTT是rt-PA溶栓治疗AIS的独立影响因素,具有临床指导意义。     

对比分析抽吸取栓与支架取栓治疗前循环大血管急性栓塞性闭塞的临床疗效

目的对比分析导管抽吸取栓与支架取栓治疗前循环大血管急性栓塞性闭塞患者的临床疗效。 方法回顾性分析2021年1月至2022年1月于南京医科大学第一附属医院接受血管内治疗的前循环大血管急性栓塞性闭塞患者的临床资料。主要观察指标是90 d改良Rankin量表（modified Rankin scale,mRS）评分。采用独立样本t检验、Mann-Whitney U检验和卡方检验比较两组患者的临床资料。单因素和多因素逻辑回归分析评价临床预后的影响因素。 结果研究期间内共纳入120例患者,其中46例（38.3%）患者接受导管抽吸取栓,74例（61.7%）患者采用支架取栓。较支架取栓相比,抽吸取栓手术时间更短（36 min vs 46 min;Z = 928.5,P < 0.001）,成功再通率（93.5% vs 75.7%;c² = 6.227,P = 0.014）、完全再通率（60.9% vs 40.5%;c² = 4.694,P = 0.039）。和90 d良好预后（mRS 0~2）比例更高（50.0% vs 31.1%;c² = 4.295,P = 0.038）。两组之间不良事件发生率（症状性脑出血和90 d死亡率）无明显差异。多因素逻辑回归分析显示抽吸取栓术和良好临床预后显著正相关（OR = 0.12,95%CI：0.03~0.49;P = 0.003）。 结论对于前循环大血管急性栓塞性闭塞患者,本单中心研究结果显示导管抽吸取栓优于支架取栓,但确切的结果还需更严格临床研究的验证。     

Prognostic factors related to clinical outcome following thrombectomy in ischemic stroke (RECOST Study). 50 patients prospective study

Background and aims

New thrombectomy devices allow successful and rapid recanalization in acute ischemic stroke. Nevertheless prognostics factors need to be systematically analyzed in the context of these new therapeutic strategies. The aim of this study was to analyze prognostic factors related to clinical outcome following Solitaire FR thrombectomy in ischemic stroke.

Methods

Fifty consecutive ischemic stroke patients with large vessel occlusion were included. Three treatment strategies were applied; rescue therapy, combined therapy, and standalone thrombectomy. DWI ASPECT score < 5 was the main exclusion criterion after initial MRI (T2, T2*, TOF, FLAIR, DWI). Sexes, age, time to recanalization were prospectively collected. Clinical outcome was assessed post treatment, day one and discharge by means of a NIHSS. Three months mRS evaluation was performed by an independent neurologist.The probability of good outcome at 3 months was assessed by forward stepwise logistic regression using baseline NIHSS score, Glasgow score at entrance, hyperglycemia, dyslipidemia, blood–brain barrier disruption on post-operative CT, embolic and hemorrhagic post procedural complication, ischemic brain lesion extension on 24 h imaging, NIHSS at discharge, ASPECT score, and time to recanalization. All variables significantly associated with the outcome in the univariate analysis were entered in the model. The significance of adding or removing a variable from the logistic model was determined by the maximum likelihood ratio test. Odds-ratio (OR) and their 95% confidence intervals were calculated.

Results

At 3 months 54% of patients had a mRS 0–2, 70% in MCA, 44% in ICA, and 43% in BA with an overall mortality rate of 12%. Baseline NIHSS score (p = 0.001), abnormal Glasgow score at entrance (p = 0.053) hyperglycemia (p = 0.023), dyslipidemia (p = 0.031), blood–brain barrier disruption (p = 0.022), embolic and hemorrhagic post procedural complication, ischemic brain lesion extension on 24 h imaging (p = 0.008), NIHSS at discharge (0.001) were all factors significantly associated with 3 month clinical outcome. ASPECT subgroup (5–7 and 8–10), and time to recanalization were not correlated to 3 months outcome. Baseline NIHSS score (OR, 1.228; 95% CI, 1.075–1.402; p = 0.002), hyperglycemia (OR, 10.013; 95% CI, 1.068–93.915; p = 0.04), emerged as independent predictors of outcome at 3 months. Overall embolic complication rate was 10%, and symptomatic intracranial hemorrhage was 2%.

Conclusion

The MCA location was associated with the best clinical outcome. A DWI ASPECT cutoff score of 5 was reliable and safe. No correlation with time to recanalization was observed in this study. NIHSS and hyperglycemia at admission were the two factors independently associated with a bad outcome at 90 days.     

高敏肌钙蛋白T动态变化在晚时间窗内进行血管内治疗的急性缺血性脑卒中患者中的预测价值

目的探讨高敏肌钙蛋白T（high-sensitivity cardiac troponin T,hs-cTnT）动态变化与晚时间窗内接受机械取栓治疗的前循环大血管闭塞型急性缺血性脑卒中患者不良预后的相关性。 方法共纳入161例患者,分别于入院时和24 h测量血清hs-cTnT。hs-cTnT升高定义为大于14 ng/L;hs-cTnT动态变化定义为两次测量值上升或下降超过20%且至少有一次大于14 ng/L。评价hs-cTnT动态变化与3个月时不良预后的相关性;比较入院时hs-cTnT升高与hs-cTnT动态变化预测3个月时不良预后的接收者操作特征（receiver-operating characteristic,ROC）曲线下面积（areas under the ROC curve,AUC）。 结果67（41.6%）例患者发生hs-cTnT动态变化。多因素分析显示,hs-cTnT升高（P = 0.014,P = 0.038）和hs-cTnT动态变化（P < 0.001,P < 0.001）分别是不良预后和死亡的独立预测因素。AUC比较显示hs-cTnT动态变化对不良预后（AUC 0.765 vs 0.689,P = 0.043）和死亡（AUC 0.818 vs 0.687,P = 0.008）的预测价值要显著优于入院时hs-cTnT升高。 结论hs-cTnT动态变化是晚时间窗进行血管内治疗的急性颅内大血管闭塞性脑卒中患者3个月时不良预后和死亡的独立预测因素。hs-cTnT动态变化对不良预后的预测价值要显著优于入院时hs-cTnT升高。     

急性缺血性脑卒中介入取栓治疗的预后及其影响因素

 目的 探讨急性缺血性脑卒中(acute ischemic stroke,AIS)介入取栓治疗的预后及其影响因素。方法 选取2017-01至2019-07在医院神经内科接受介入取栓治疗的106例AIS患者,根据术后3个月患者改良Rankin评分评估预后水平,分为预后良好组和预后不良组,对两组患者各项临床资料进行分析,对比预后的相关因素及危险因素,并对认知功能和预后血清神经相关因子表达水平进行对比。结果 患者年龄大、合并冠心病、术前血清CRP及Hcy高、阻塞血管再通时间较长、术后36 h存在部分再通均为AIS介入治疗预后不良的危险因素(OR>1,P<0.05);预后良好组的认知功能、运动功能、语言功能均优于预后不良组,差异有统计学意义(P<0.05);两组患者吞咽功能差异无统计学意义。预后良好组血清神经相关因子表达水平均优于预后不良组,差异有统计学意义(P<0.05)。结论 预后良好AIS患者各项功能与血清神经相关因子表达水平状态均较好,对年龄较大、发病至就诊时间较长、合并冠心病,且术前血清CRP、Hcy、NIHSS评分偏高,阻塞血管再通时间较长及术后36 h内仅达到部分再通的患者应给予充分重视,对危险因素积极预防,提高预后水平。     

Mechanical thrombectomy for acute stroke

BACKGROUND AND PURPOSE: We evaluated a mechanical thrombectomy protocol to treat acute stroke and report the angiographic results and clinical outcomes. METHODS: Patients with anterior circulation strokes <8 hours and posterior circulation strokes <12 hours were treated at a single center over 10 months. Patients were excluded if they were candidates for intravenous tissue plasminogen activator (tPA). Treatment involved one of two mechanical thrombectomy devices. Retrieval was augmented by low-dose intra-arterial tPA if needed. Outcome was measured by using the Modified Rankin score. RESULTS: Ten patients were treated: five with anterior circulation strokes, four with posterior circulation strokes, and one with embolic strokes involving both circulations. Mean National Institutes of Health Stroke Scale score at presentation was 24.6 +/- 10.9. In eight patients (80%), revascularization was successful (Thrombolysis in Acute Myocardial Infarction score, 3). Mean time from symptom onset to initiation of the procedure was 6 hours (5.3 hours for anterior circulation and 7.0 hours for posterior circulation). Mean time for recanalization from the start of the procedure was 1.17 +/- 0.58 hours for the six anterior circulation strokes and 2.75 +/- 1.34 hours in the two posterior circulation strokes. Five patients died within 48 hours; all had posterior circulation strokes. Mean Modified Rankin score at 90 days was 1.4. CONCLUSION: In this small series, mechanical thrombectomy of acute stroke appeared to improve recanalization rates compared with intra-arterial thrombolysis. No hemorrhagic complications occurred. Further study is required to determine the role of these techniques.