A bedside test for cerebral autoregulation using transcranial Doppler ultrasound

Summary Although disorders of cerebral autoregulation are commonly seen in neurosurgical disease, there is currently no test of autoregulation in widespread use that may be performed safely at the bedside. The presence of autoregulation, however, can be seen in the brief hyperemic response in the middle cerebral artery distribution following a transient manual carotid artery compression in the neck. This transient hyperemic response (THR) is readily measured with transcranial Doppler techniques, and therefore might serve as a qualitative marker of cerebral autoregulation.To evaluate the THR as a clinical tool, carotid compressions were performed during 172 TCD studies on 79 patients with neurosurgical disorders and on 10 patients without cerebral disease. The results were correlated with clinical status (e.g., Hunt-Hess Grade for subarachnoid hemorrhage and Glasgow Coma Score for trauma). There were no complications arising from the compressions. A separate assessment of autoregulation was made from TCD recordings obtained intraoperatively during 16 procedures and correlated to the pre-operative THRs. Autoregulation was further assessed in 4 patients during a hypotensive challenge, and again compared to the THRs.A strong correlation was seen between the THR results and clinical status. The THR was also strongly correlated with the intraoperative assessments, and all 4 patients receiving hypotensive challenges had abnormal THRs and demonstrated evidence of poor autoregulation during the challenge. None of the control patients had abnormal THRs.The THR arising from transient artery compression is readily detected with TCD techniques and correlates well with clinical status and other indicators of autoregulatory ability. The THR test can be safely performed at the bedside, uses noninvasive technology, and may emerge as a useful marker of cerebral autoregulation.     

Cerebral haemodynamics in internal carotid artery trial occlusion

Summary The purpose of this study was to analyse the cerebral haemodynamic changes brought about by trial occlusion of the internal carotid artery (ICA). Sixteen patients with surgically inaccessible cerebral aneurysms, carotid cavernous fistulas or neck neoplasms were monitored with transcranial Doppler ultrasonography (TCD) during 90–120 s angiographie ICA balloon occlusion or ICA closure with a Selverstone clamp. The blood velocity (V) was registered continuously in both middle cerebral arteries (MCA) while the pulsatility index (PI_MCA) and haemodynamic tension (U_hemmca ) were calculated.ICA closure led to an instantaneous drop in the ipsilateral V _mca , PI _mca and U_hemmca . The V _mca thereafter increased gradually until reaching a stable level. The subjects were grouped into those with initial drops in V _mca to 60% of pre-occlusion value (group 1) and those that fell to < 60% (group 2), respectively. In group 1 autoregulatory mechanisms made the PI _mca decline further, while the U_hemmca remained unaltered during ICA closure. In group 2, however, the PI _mca did not change further, while the U_hemmca increased slightly. The cerebral haemodynamic features during ICA test occlusion were thus essentially different in the two groups. On re-opening the ICA, there was an overshoot in V _mca and U_hemmca . Contralaterally, the V _mca was increased during ICA occlusion.Seven of the patients later had their ICA closed permanently. While none of five group 1 patients developed haemodynamic complications, two group 2 individuals experienced haemodynamic stroke. Assuming ICA sacrifice is feasable when test occlusion results in an ipsilateral initial reduction in V _mca to 60% of preocclusion value, the corresponding limit for the U_hemmca is 40%. In the pre-operative evaluation of the haemodynamic risk related to ICA loss, TCD emerges as a reliable method. It also seems to allow for the reduction of test occlusion time to 90–120 s.     

Haemodynamic classification of symptomatic obstructive carotid artery disease

Summary 63 subjects with symptomatic obstructive carotid artery disease were investigated with transcranial Doppler ultrasonography. Their blood velocities at rest (V) in the middle and posterior cerebral artery (MCA and PCA) and in the extracranial internal carotid artery were measured and the pulsatility index (PI) and U_hem index (V _mca ·PI _mca /V _pca ·PI _pca ) calculated. The vasomotor responses in both MCAs were also tested.The subjects were divided into groups based on the findings on physical examination and cerebral computed tomography. In the patient group with lacunar/territorial infarction we found in the stroke hemisphere: V _mca > V _pca , PI _mca = PI _pca and normal values for the U_hem index and total vasomotor reactivity. In the patient group with watershed infarction this hemisphere was characterized by: V _mca < V _pca , PI _mca < PI _pca and subnormal scores for the U_hem index and total vasomotor reactivity. Displaying features from both stroke groups, we obtained in the hemisphere of interest in patients with transient ischaemic attacks: V _mca = V _pca , PI _mca < PI _pca and normal values for the U_hem index and total vasomotor reactivity. Five patients with clinical evidence of stroke but with negative cerebral computed tomography findings had scores similar to those of the watershed group of patients.For the stroke patients, individual measurements of V, PI and total vasomotor reactivity failed to clearly identify to which stroke group a subject might belong. However, such an identification was achieved in all subjects when using the U_hem index. The U_hem index data in patients with transient ischaemic attacks suggest two subgroups with different pathogenesis underlying the ischaemic events.     

Ruptured aneurysm at a duplicated middle cerebral artery with accessory middle cerebral artery

Summary. Although many cerebral vascular anomalies are widely recognized, others are less well known or unclassified. Accessory middle cerebral artery (MCA) and duplicated MCA are among uncommon anomalies. We present a very rare case of subarachnoid haemorrhage due to rupture of a saccular aneurysm arising from a duplicated middle cerebral artery which was associated with an accessory middle cerebral artery.     

Characteristics of aneurysms of the internal carotid artery bifurcation

Summary Background. Arterial bifurcations are sites of maximal hemodynamic stress, where cerebral aneurysms commonly develop. However, in our experience with endovascular treatment for aneurysms of the internal carotid artery (ICA) bifurcation, we often experienced that the aneurysmal neck did not necessarily exist only at the ICA bifurcation (ICBi). In this study, we have retrospectively evaluated characteristics of aneurysms at the ICBi. Methods. Ten ICBi aneurysms in 10 consecutive patients were studied retrospectively. The size of the aneurysms, the angles formed between the ICA and the anterior cerebral artery (ACA) and middle cerebral artery (MCA), and the diameter of the ICA, ACA and MCA were measured. Furthermore, to study the relationship between the location of the aneurysmal neck and the bifurcation of the ICA, the distance between the midline of the aneurysmal neck and of the ICA was measured. Results. The average aneurysm size was 6.3 ± 3.2 mm and the average neck was 3.1 ± 1.2 mm. The average ICA-ACA angle was 57.3 ± 16.5 degrees, and the average ICA-MCA angle was 128.9 ± 24.1 degrees. The average diameters of the ICA, ACA and MCA were 2.9 ± 0.5 mm, 1.9 ± 0.4 mm and 2.5 ± 0.4 mm, respectively. The average distance between the midline of the aneurysmal neck and the ICA was 1.6 ± 0.6 mm, and all aneurysmal necks of the ICBi arose from the side of the ACA. Conclusion. ICBi aneurysms were deviated to the side of the A1 segment of the ACA, where the artery might suffer higher hemodynamic stress.     

Rat middle cerebral artery occlusion using an intraluminal thread technique

Summary A modification of the previous methods of producing cerebral ischaemia in rats (Koizumiet al., Longaet al.), using an intraluminal thread technique, is described. The middle cerebral artery is occluded by introducing a simple 3–0 nylon thread (0.20–0.249 mm in diameter) through the internal carotid artery in the neck. It has been proven that with this method reproducible focal cerebral ischaemia can be achieved which resembles human stroke.Therefore this simple and relatively non-invasive model is suitable for the pathophysiological investigation of ischaemic stroke and the testing of potential therapies.     

颈动脉支架术中脑保护措施的应用

颈动脉狭窄是造成脑卒中的主要原凼.颈动脉支架置人术治疗颈动脉狄窄对患者创伤小、痛苦少,已逐渐成为治疗颈动脉狭窄的首选术式.而术中脑保护装置的应用更大大提高了其疗效.本文对颈动脉成形术中应用脑保护的有关问题进行概述.相信随着许多大规模、多中心临床实验的完成,脑保护下的颈动脉支架置入术将在颈动脉狭窄患者的卒中预防和治疗中发挥重要作用.     

Anomalies of the P1 segment of the posterior cerebral artery: Early bifurcation or duplication,fenestration, common trunk with the superior cerebellar artery

Summary In a series of anatomical dissections on 100 fixed human brains, 3% of anomalies of the precommunicating segment of the posterior cerebral artery (P1) were found, among which a case of duplication of the P1 segment. This finding is very unusual and it is much rarer than the many other anatomical patterns reported in the circle of Willis. It is to be considered a very early bifurcation, as reported at the middle cerebral artery level. Another two unusual anatomical patterns were found. One was a large fenestration of the P1 segment, which is rather frequent in the vertebrobasilar system. The other was a bilateral common trunk between the posterior cerebral artery and the superior cerebellar artery, which represents a rare anatomical variation. The existence of such anomalies can be explained by the embryological development of the region. Their pathogenic and neurosurgical implications are discussed in the light of the literature.     

Aneurysm in the penetrating artery of the distal middle cerebral artery presenting as intracerebral haemorrhage

Summary We are recording the first reported case of a 20-year-old man with an intracerebral haemorrhage due to a ruptured aneurysm, which arose from a penetrating artery of the distal middle cerebral artery (MCA; M₄ segment). Excision of the aneurysm was successfully achieved via a right pterional approach. The follow-up angiogram demonstrated filling of the parent vessel and no residual aneurysm. This report illustrates the angiographical finding of a penetrating artery aneurysm of the distal MCA and summarizes the previous reports to discuss their pathological and clinical characteristics.     

Normal values of volume flow in the internal carotid artery measured by a new angle-independant Doppler technique for evaluating cerebral perfusion

Summary Background. Cerebral blood flow is an important parameter when monitoring critically ill patients. Blood flow volume within the internal carotid artery (ICA) was shown to be correlated with the cerebral blood flow. The aim of our study was to provide normal values of the internal carotid artery volume flow using this new technology (QuantixND, Cardiosonix Ltd., Israel).Method. The QuantixND System is an angle-independant Doppler system that employs two digital high resolution ultrasound heads within one probe in an defined angle to each other. Thus several flow velocities within the vessel and the vessel diameter can be measured. 77 healthy patients (41 women, 36 men) were included and divided into age groups of ten-year intervals (mean age 48.9 years). Internal carotid artery flow was evaluated as well as physiological and hematological parameters (hematocrit, arterial blood pressure etc).Findings. We found that the blood flow volume in the ICA decreased significantly with age. No side-to-side effects as well as no gender-related differences could be observed. There was no influence of hemoglobin, hematocrit and blood pressure in this healthy population.Conclusions. There is an age-related decrease in blood flow volume with age that can be easily and exactly determined by the use of the new angle-independant doppler technique.     

Dissecting aneurysms of the anterior cerebral artery and accessory middle cerebral artery. Case report

A 66-year-old woman presented with dissecting aneurysms of the anterior cerebral artery (ACA) and accessory middle cerebral artery (MCA) manifesting as subarachnoid hemorrhage but without radiological evidence of the dissecting aneurysms. Intraoperative observation revealed that the vessel walls were dark purple in color, a typical finding of dissecting aneurysm. The abnormal A1 segment was trapped and the dissecting aneurysm of the accessory MCA was wrapped. In the case of SAH of unknown origin, dissecting aneurysm should always be kept in mind even if the angiogram does not show any abnormal finding. This is the first reported case of dissecting aneurysm of the accessory MCA.     

The surgery of middle cerebral artery aneurysms

Summary Aneurysms of the middle cerebral bifurcation represent an interesting entity among intracranial saccular aneurysms. Their shape, size, situation, and in particular their relation to the middle cerebral trunk and its branches show wide variations. Topographical analysis of the angiograms offers a great deal of interest in planning surgery.Our experience with 289 patients with middle cerebral artery aneurysms operated on since 1977 are presented. Factors such as number of previous haemorrhages, timing of surgery, preoperative condition, major intraoperative bleeding or brain oedema and delayed postoperative deterioration play a major role in the outcome. Others such as severity of the subarachnoid bleed, age, size of the sac seem to have much less influence.     

Microsurgical neurovascular anastomosis: The example of superficial temporal artery to middle cerebral artery bypass. Technical principles

The superficial temporal artery to the middle cerebral artery (STA-MCA) bypass is a good example of cerebrovascular anastomosis. In this article, we describe the different stages of the procedure: patient installation, superficial temporal artery harvesting, recipient artery exposure, microsurgical anastomosis, and closure of the craniotomy. When meticulously performed, with the observance of important details at each stage, this technique offers a high rate of technical success (patency > 90%) with a very low morbi-mortality (respectively 3% and 1%). Some anesthetic parameters have to be considered to insure perioperative technical and clinical success. STA-MCA bypass is a very useful technique for the management of complex or giant aneurysms where surgical treatment sometimes requires the sacrifice and revascularization of a main arterial trunk. It is also a valuable option for the treatment of chronic and symptomatic hemispheric hypoperfusion (Moyamoya disease, carotid or middle cerebral artery occlusion).     

颈内动脉闭塞术的初步临床应用

目的探讨颈内动脉闭塞术治疗颈内动脉血管性病变的价值。方法共5例患者,1例鼻咽癌行放疗后清创术,并发难以制止的鼻咽部大出血,双侧后鼻孔填塞无效;1例巨大颈内动脉眼段动脉瘤,无法手术夹闭;3例外伤后颈内动脉海绵窦瘘,单纯闭塞瘘口失败。采用Seldinger技术经股动脉穿刺置管行全脑血管造影,经球囊闭塞试验或病变侧压颈试验,病人耐受良好后方行闭塞术。闭塞材料为3例应用可脱弹簧圈,2例应用可脱球囊,闭塞位置为病变近端及瘘口。结果所有病例闭塞颈内动脉后,即行对侧颈动脉造影复查,可见前交通动脉和/或后交通动脉代偿良好,患者无明显并发症发生,病变未见显影。临床症状消失、无合并症发生,病变未见复发。结论颈内动脉闭塞术作为一种治疗颈动脉血管性疾病的方法,可以在不危及病人生命、加重病人病情的情况下,取得良好的治疗效果。     

Patterns of brain infarctions in internal carotid artery dissections

In 15 patients with internal carotid artery (ICA) dissections, patterns of brain infarctions visible on CT were categorized according to a pathogenetically oriented classification system. This differentiated ischemic brain damage due to low flow from thromboembolic infarctions. Simultaneously, cerebral hemodynamic reserve was evaluated by means of both CO2-dependent vasomotor reactivity and HMPAO- and ^{99 m}Tc-RBC-SPECT. Six out of 11 patients with ischemic infarctions had the territorial type of brain lesion, suggesting distal embolism. Five patients revealed the pattern of hemodynamically induced low-flow infarctions. Cerebral hemodynamic reserve was significantly decreased only in these latter patients. In ICA dissections the frequencies of hemodynamically and thromboembolically induced brain infarctions is approximately equal. This finding suggests that only half of the patients with symptoms of symptomatic dissections had brain emboli, whereas in the other half the dissections lead to a low-flow effect in terminal supply areas which is so severe that non-embolic brain infarctions occur. This differentiation can help decide whether antithrombotic or hemodynamic treatment should be given.     

颈动脉斑块常规超声及超声造影预测颈动脉狭窄患者缺血性脑卒中

目的 观察常规超声及超声造影(CEUS)评估颈动脉斑块、预测颈动脉狭窄患者缺血性脑卒中的价值。方法 回顾性分析115例经超声证实的颈动脉斑块致狭窄(狭窄率≥50%)患者,根据近6个月内有无缺血性脑卒中将其分为症状组(n=53)及无症状组(n=62)。以单因素分析及多因素logistic回归分析筛选颈动脉狭窄患者发生缺血性脑卒中的颈动脉斑块超声特征,建立回归模型,绘制受试者工作特征(ROC)曲线,评估其预测患缺血性脑卒中的效能。结果 单因素分析显示,组间颈动脉狭窄率、斑块表面形态及斑块内新生血管分级差异均有统计学意义(P均<0.05)。多因素logistic回归分析显示,斑块表面形态及斑块内新生血管分级为颈动脉狭窄患者发生缺血性脑卒中的独立预测因素,建立回归模型Y=－4.914+2.272X₁+2.354X₂(X₁为斑块表面形态,X₂为斑块内新生血管分级),其预测缺血性脑卒中的曲线下面积为0.886。结论 常规超声联合CEUS评估颈动脉狭窄患者颈动脉斑块有助于预测缺血性脑卒中。     

Distal middle cerebral artery aneurysm: A proposition of microsurgical management

Objectives

Based on a cohort of patients treated on distal middle cerebral artery (MCA) aneurysm by microsurgical approach, the objectives were to assess the following: the postoperative functional outcome, study the causes of early neurological deterioration and to determine the predictive factors of favourable outcome.

Patients and methods

From a neurovascular prospective database, this retrospective longitudinal study included all the patients treated for cerebral aneurysm located on the distal segment of the MCA over two decades (January 1990–December 2011). The patients were all treated by microsurgical clipping exclusion. Any aneurysm was associated to infectious angiopathy. Data were retrieved from the patient's medical charts. The outcome was analysed twice: during the immediate postoperative period and at 6 months according to the modified Rankin scale. The relative risk was estimated for each variable and the prognostic factors were assessed using a multivariate logistic regression model (P < 0.05).

Results

Twenty-eight patients, mean age 40 ± 13.3 years (median: 43 years; range 6–70 years) were divided into the ruptured group (n = 20) and unruptured group (n = 8). In the ruptured group, the initial clinical status was good (WFNS I–III) in 12 patients (60%) and poor in eight (40%) with an intracerebral haematoma (ICH) in 11 (55%). For both groups, the aneurysm location on the distal MCA decreased at a rate from 64.8% of the insular segment to 25% of the opercular then 10.7% to the cortical. During the hospital stay, neurological deterioration occurred in 16 patients (57.2%). The diagnosed causes were cerebral ischaemia in 10 (35.6%), initial ICH in three (10.7%), hydrocephalus in two (7.1%) and epilepsy in one (7.1%). At 6 months, a favourable outcome (mRS 0–2) was observed in 19 patients (68.1%), a definitive morbidity in seven (24.9%) and death in two (7.2%). Based on the prognostic factors, only the absence of immediate postoperative neurological deterioration was identified as significant for a favourable outcome.

Conclusion

These rare cerebral aneurysms resulted in a high proportion of poor initial status related to a frequent ICH. Cerebral ischaemia was a major cause of the immediate neurological deterioration and the absence of immediate neurological deterioration was the single identified prognostic factor.     

Preoperative angiographical prediction of the necessity to removal of the anterior clinoid process in internal carotid-posterior communicating artery aneurysm surgery

Summary During the last 10 years, we had to resect the anterior clinoid process (ACP) before applying the clip in three of the 70 patients with internal carotid-posterior communicating artery (ICPCom) aneurysms. To reveal the angiographic characteristics in these three patients, we measured the following parameters on carotid angiograms in all 70 patients: 1) the angle between the midline of the skull and the axis of the C 1 segment of the internal carotid artery (ICA) on A-P view (angle A), 2) the angle between the axes of the C1 and C2 segments of the ICA on A-P view (angle B), and 3) the distance between the posterior wall of the carotid knee and the proximal aneurysmal neck on lateral view (distance d). The common angiographic features of these three patients were as follows: 1) angle A was larger than 60 degrees, 2) angle B was less than 90 degrees, 3) distance d was less than 10mm, and 4) the posterior communicating artery was of the foetal type.The present results suggest that preoperative angiogram can predict whether or not the ACP should be removed during ICPCom aneurysm surgery.     

Combined subclavian-external carotid and superficial temporal-middle cerebral artery bypass graft

A variation of a superficial temporal-middle cerebral artery bypass is presented that can serve as a surgical alternative to long vein subclavian-middle cerebral artery grafting in patients with common carotid artery occlusion and symptoms of ipsilateral ischemia. A vein graft from the subclavian to the external carotid artery at the carotid bifurcation is performed simultaneously with a standard superficial temporal-middle cerebral artery bypass. Advantages of this procedure over a long subclavian-middle cerebral artery vein graft are the technical simplicity associated with a standard superficial temporal-middle cerebral artery bypass, higher patency rates, and lower risk of graft leakage or torsion. Three patients have undergone this procedure, and all had patent bypasses one year after operation.