Transcranial sonographic monitoring of the blood flow of the middle cerebral artery in recanalizing operations of the extracranial internal carotid artery

During endarterectomy of the internal carotid artery (ICA) blood flow velocity of the ipsilateral medial cerebral artery (MCA) was continuously monitored in twelve patients with the help of a new transcranial pulsed Doppler system. Additionally, the basal cerebral arteries where examined pre- und postoperatively in order to evaluate criteria for selective intraoperative shunting and to document flow improvement following ICA reconstruction. All patients had symptoms, either of TIA or of minor stroke. Five of them had in addition a contralateral ICA occlusion. During intraoperative carotid cross-clamping on the patients with unilateral ICA lesions, MCA blood flow dropped to zero in only one of them. In the other cases, a 20 to 60% flow reduction occurred indicating cross-filling or/and collateral blood supply via the posterior circulation. More severe MCA flow reductions were found in patients with contralateral ICA occlusion, with the occurrence of a no-flow state in two of them. All patients were operated on with an indwelling shunt. Its effect on MCA blood flow varied considerably. Apparently, the shunt was necessary in some patients but was superfluous in the majority of them. Transcranial Doppler meets the basic criteria of an examination technique to be recommended for monitoring. The method is noninvasive. The parameter, i.e. MCA flow velocity, can be evaluated on-line. It is representative and highly sensitive for cerebral circulatory disturbances and impending ischemia in the carotid territory. Transcranial MCA flow monitoring does not affect the course of the operation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Usefulness of transcranial color-coded sonography in the diagnosis of cerebral vasospasm

BACKGROUND AND PURPOSE: The noninvasive diagnosis of cerebral vasospasm with the use of conventional transcranial Doppler ultrasonography (TCD) is based on a velocity study of the middle cerebral artery (MCA). The authors report a prospective comparative study between transcranial color-coded sonography (TCCS), conventional transcranial Doppler (TCD), and angiography in the diagnosis of cerebral vasospasm after surgical treatment for aneurysm. METHODS: Thirty consecutive patients underwent routine angiography after surgical treatment for intracranial aneurysm. The distribution of vasospasm was determined after a prospective calculation of the angiographic diameter of the MCA, internal carotid artery (ICA), and anterior cerebral artery (ACA). The blood flow velocities (systolic and maximum) of the MCA, ICA, and ACA were evaluated by TCCS and TCD. RESULTS: The correlation between mean maximum velocity and angiographic diameter was significant for the MCA (r=-0.637, P<0.0001), ICA (r=-0.676, P<0.0001), and ACA (r=-0.425, P<0.01). TCCS sensitivity and specificity were higher than those for TCD for MCA (100% and 93%, respectively) and ICA (100% and 96.6%, respectively). For ACA, the sensitivity and specificity were 71.4% and 84.8%, respectively. CONCLUSIONS: The authors suggest that TCCS is useful for accurate monitoring of cerebral vasospasm in the MCA and ICA. In the ACA, TCCS monitors the hemodynamic state of the anterior part of the circle of Willis, which could expose the patient to a delayed ischemic deficit.     

Transcranial Doppler evaluation of cerebral infarction in the neonate

We recorded cerebral artery flow velocities (CAFV) in two neonates with cerebral infarction, using transcranial Doppler sonography (TCD). Cerebral infarction was diagnosed by brain imaging. The arteries investigated were the middle cerebral artery (MCA), the internal carotid artery (ICA) and the anterior cerebral artery (ACA). The whole territory of right MCA was involved. A decrease in CAFV was noted in MCA and ICA of the affected side. Furthermore, early recordings of CAFV allowed us to distinguish perinatal infarction from antenatal infarction: in the former, Doppler signal was completely absent during the first days of life whereas in the latter, Doppler signal was reduced but present. The process of recanalization could be followed. The asymmetry of CAFV recorded in the neonatal period seems to persist definitively at least in MCA. These Doppler data correlate well with the evolutive stages of cerebral infarction shown by brain imaging. Beside US, CT and MRI scans, TCD may be a useful adjunct for identifying and following infants with suspected occlusion of major cerebral vessels.     

Color-coded Ultrasound Diagnosis of Vascular Occlusion in Acute Ischemic Stroke

A combination of extracranial and transcranial color-coded sonography was used to identify the patterns of vascular occlusion in 47 patients with acute ischemic stroke. Total anterior circulation infarction (n = 20) was associated with internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion (n = 8 and 9, respectively), or with significant reduction in ipsilateral MCA velocities (n = 5) Patients with partial anterior circulation (n = 22) infarction had patency of the ipsilateral ICA and MCA. In this group, significant reduction of ipsilateral MCA velocities (n = 7) was associated with more extensive infarcts on conventional neuroimaging (n = 6), suggesting multiple MCA branch occlusions. Ultrasound imagmg was unable to identify underlying vascular pathology in patients with postenor circulation infarction or with lacunar infarction (n = 5). An ultrasound-based approach enables noninvasive identification of major vascular pathology of the anterior cerebral circulation in patients with acute cerebral infarction. It may be useful for the rapid identification of patients most and those least likely to benefit from acute intervention, and for monitoring their response.     

Source of cerebral microembolic signals in occlusion of the internal carotid artery

Background and purpose: There are several possible sources of cerebral embolic ischaemia distal to an occlusion of the internal carotid artery (ICA). Our aim was to identify the source of microembolic signals in the ipsilateral middle cerebral artery (MCA) by taking simultaneous bitemporal transcranial Doppler ultrasound recordings of the ipsilateral MCA and the contralateral ACA to find the route of potential microembolic material to MCA. Subjects and methods: The study group consisted of 38 patients with an occlusion of the ICA. With extracranial duplex sonography (ACUSON 128 XP; 7 MHz), performed by an experienced sonographer, the echo intensity and echo structure of the occluded ICA in the extracranial part (proximal) were classified as homogeneous or inhomogeneous. In addition, affected segments of the ipsilateral and contralateral carotid artery with arteriosclerotic vessel walls were compared. Microembolic signals were recorded with transcranial Doppler (TCD) monitoring. The microemboli counts in the MCA and ACA were added to the sum scores. Results: The number of affected segments of the carotid artery on the ipsilateral (the bifurcation, the external or common carotid artery) and contralateral side of occluded ICA were equally distributed. In ipsilateral MCA 3.1, 7.1 microemboli (average mean, SD) with a range of between 0 and 34 were counted, in the contralateral ACA 0.3, 0.6 (range of between 0 and 2). Regression analysis confirmed the non-predictability of the microemboli variance on the ipsilateral side of the occlusion from the variance on the contralateral side (multiple r: 0.024). We found no significant correlation between the echo intensity or echo structure of the occluded artery and an increased rate of microemboli in the ipsilateral MCA. Conclusions: Our results indicate a predominantly ipsilateral source for cerebral microemboli in ICA occlusion. The rate of cerebral microembolic signals was not influenced by the echo structure and echo intensity of the occluded ICA. Received: 24 May 1996 Received in revised form: 20 January 1997 Accepted: 31 January 1997     

颈动脉严重狭窄或闭塞的脑血流动力学改变

目的分析颈内动脉严重狭窄或闭塞(ICA SO)后颅内血液动力学的改变,以提高经颅多普勒超声(TCD)对ICA SO的检出率和准确性。方法ICA SO患者75例,全部经颈部血管彩超检查证实,其中12例经脑血管造影(DSA)或核磁血管造影(M RA)进一步确诊。双侧病变7例,单侧病变68例,共有病变血管82条(狭窄42条,闭塞30条)。全部行TCD检查。结果(1)狭窄或闭塞侧大脑中动脉(M CA)的收缩期血流速度(SPV)及脉动指数(P I)明显低于对侧;(2)前交通动脉(ACoA)开放的患者健侧大脑前动脉(ACA)的峰值流速明显快于ACoA未开放的患者,P I值低于后者;(3)眼动脉之前的ICA SO,患侧虹吸段血流与对侧相比具有明显的低流速低搏动改变;眼动脉之后的ICA SO,患侧虹吸段与对侧相比具有明显的低流速高阻力改变,发出眼动脉之前和之后的ICA SO二者虹吸段收缩期流速无明显差异,但前者P I值明显低于后者;(4)颈外-颈内动脉(ECA-ICA)侧支开放的患者患侧与健侧滑车上动脉(S trA)血流速度无明显差异,但P I值明显低于健侧;(5)前交通动脉(ACoA)开放占50.67%(38/75),后交通动脉(PCoA)开放占52.00%(39/75),颈外-颈内动脉侧支(ECA-ICA)开放占75.44%(43/57)。结论增强对ICA SO时颅内血液动力学改变的认识能提高对ICA SO的检出率和准确性。     

Factors affecting the angiographic recanalization and early clinical improvement in middle cerebral artery territory infarction after thrombolysis

BACKGROUND: Factors affecting the angiographic recanalization (AR) and clinical improvement (CI) still remain unclear in patients receiving thrombolytic therapy. OBJECTIVES: To elucidate factors related to AR and early CI in patients with middle cerebral artery (MCA) or internal carotid artery (ICA) occlusion. DESIGNS: Retrospective study. SETTING: Department of Neurology, Asan Medical Center, Seoul, South Korea. PATIENTS: We studied 42 patients who (1) underwent diffusion-weighted magnetic resonance (MR) imaging and MR angiography within 6 hours after onset, (2) had MCA territory infarction, (3) had nonvisualization of the MCA or the ICA on initial MR angiography, (4) were treated with thrombolytics, and (5) underwent follow-up MR imaging and MR angiography at day 2 or 3. RESULTS: Successful AR and CI were achieved in 31 and 16 patients, respectively. Angiographic recanalization was related to CI (P<.01), lower follow-up National Institutes of Health Stroke Scale scores (P<.05), the absence of a dominant ipsilateral posterior cerebral artery (P<.01) on initial MR angiography, and the sparing of the internal capsule on both initial (P<.05) and follow-up (P<.01) MR imaging. Clinical improvement was associated with the absence of ICA (vs MCA) flow signals (P<.05), the sparing of the internal capsule (P<.01), and marginally, with the infarct volume change (P = .06). CONCLUSIONS: In patients with MCA or ICA occlusion, CI after thrombolysis is related to the AR and the sparing of the critical motor pathway. The presence of a dominant ipsilateral posterior cerebral artery may predict poor AR after thrombolysis.     

External Carotid Artery Angioplasty and Stenting Followed by Superficial Temporal Artery to Middle Cerebral Artery Anastomosis

A 31-year-old man presented with right hemiparesis, and magnetic resonance imaging revealed a small infarct at left basal ganglia. Digital subtraction angiography showed left cervical internal carotid artery (ICA) occlusion and severe stenosis of the ipsilateral external carotid artery (ECA) with collateral cerebral circulation fed by ECAs. Based on the results of a functional evaluation of cerebral blood flow, we performed preventive ECA angioplasty and stenting for advanced ECA stenosis to ensure sufficient blood flow to the superficial temporal artery. Eight weeks later, superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis was performed. His postoperative course was uneventful and no additional transient ischemic attacks have occurred. To our knowledge, this is the first report of preventive angioplasty and stenting for advanced narrowing of an ECA before STA-MCA anastomosis for ipsilateral ICA occlusion.     

External carotid artery stenting in symptomatic internal carotid artery occlusion

We report the case of a patient with an anterior ischemic stroke due to tandem occlusion of the left M2 segment and ipsilateral internal carotid artery (ICA), with concomitant severe stenosis of the ipsilateral external carotid artery (ECA) and contralateral ICA, and moderate stenosis of the left vertebral artery (VA); as thrombectomy was not possible, stenting of the right ICA was performed. Two days after significant recovery, the patient showed neurological deterioration when in upright position, and brain magnetic resonance imaging confirmed decreased cerebral blood flow on the left hemisphere. Stenting of the left ECA and balloon angioplasty of the ipsilateral VA were performed in order to increase collateral flow, with an almost complete resolution of symptoms. This case highlights the importance of assessing the collateralization pattern when an ICA occlusion is present, and the potential need to revascularize an ipsilateral stenotic ECA.     

Hyperechoic middle cerebral artery: acute occlusion detected by transcranial duplex ultrasonography.

The authors describe the appearance of acute thromboembolic occlusion of the middle cerebral artery (MCA) using transcranial duplex ultrasonography. Acute occlusion of the MCA commonly leads to severe cerebral infarction. In patients with acute MCA occlusion, secondary edema and elevated intracranial pressure are major causes of increased morbidity and mortality. Thus, the prompt detection of occlusion influences early therapy, including thrombolysis and increased control of intracranial pressure. The hyperdense appearance of the acutely occluded MCA as seen using computed tomography (CT) has been extensively reported in the literature. However, its appearance using transcranial duplex ultrasonography has not been reported. The authors report four patients who had clinical features of ischemia throughout the MCA territory. All patients were studied with CT and transcranial duplex ultrasonography within 6 hours of the onset of symptoms. Head CT of all four patients showed a hyperdense MCA sign with infarction of the MCA territory. Transcranial duplex studies using either pulsed Doppler or color Doppler sonography displayed a hyperechoic MCA with no evidence of flow. Subsequent duplex ultrasonography and magnetic resonance angiography showed all four patients had ipsilateral occlusion of the internal carotid artery. Transcranial duplex ultrasonography assists in the early diagnosis of acute MCA occlusion. The affected vessel is displayed as a hyperechoic structure associated with no flow using Doppler examination.     

Severe ipsilateral carotid stenosis and middle cerebral artery disease in lacunar ischaemic stroke: innocent bystanders?

Objectives Lacunar infarcts are thought to be mostly due to intracranial small vessel disease. Therefore, when a stroke patient with a relevant lacunar infarct does have severe ipsilateral internal carotid artery (ICA) or middle cerebral artery (MCA) disease, it is unclear whether the arterial disease is causative or coincidental. If causative, we would expect ICA/MCA disease to be more severe on the symptomatic side than on the asymptomatic side. Therefore, our aim was to compare the severity of ipsilateral with contralateral ICA and MCA disease in patients with lacunar ischaemic stroke. Methods We studied 259 inpatients and outpatients with a recent lacunar ischaemic stroke and no other prior stroke. We used carotid Duplex ultrasound and transcranial Doppler (TCD) ultrasound to identify ICA and MCA disease, and compared our results with previously published data. Results In our study, there was no difference between the severity of ipsilateral and contralateral ICA stenosis within individuals (median difference 0 %, Wilcoxon paired data p=0.24, comparing severity of ipsilateral and contralateral stenosis). The overall prevalence of severe ipsilateral stenosis was 5 %, and the prevalence of severe contralateral stenosis was 4 % (OR 1.6, 95 % CI 0.6, 4.8). There was no difference in the prevalence of ipsilateral and contralateral MCA disease. A systematic review of the other available studies strengthened this conclusion. Conclusion Carotid stenosis in patients with a lacunar ischaemic stroke may be coincidental. Further studies are required to elucidate the causes of lacunar stroke, and to evaluate the role of carotid endarterectomy. Received: 24 February 2001, Received in revised form: 15 June 2001, Accepted: 3 July 2001     

Transient ischaemic attacks due to hypoplasia of the internal carotid artery in a patient with congenital Horner's syndrome

INTRODUCTION: Hypoplasia of the internal carotid artery (ICA) is a rare developmental anomaly sometime revealed by transient ischaemic attaks (TIA). Association with a Horner's syndrome is very rare. CASE REPORT: We report the case of a 42-year-old woman who presented with a TIA and a cervical murmur. Horner's syndrome with iris hypopigmentation was present shortly after birth. Magnetic resonance imaging showed no dissection but hypoplasia of the ICA. Blood flow in the ICA was antegrade through several branches constituting a rete mirabile across the carotid canal, and via collateral arteries from ipsilateral external carotid artery. CONCLUSION: Horner's syndrome in the setting of TIA evokes a carotid dissection. A skull base CT scan demonstrating carotid canal hypoplasia can rule out an ICA dissection and allows diagnosis of a congenital arterial anomaly.     

Cerebral blood flow correlated with carotid blood flow in neurologically normal elderly with severe white matter lesions

Previous studies of white matter signal hyperintensity (WMSH) on T ₂-weighted MRI (magnetic resonance imaging) have shown it to he related to decreased cerebral blood flow (CBF). However, there have been few studies on the relationship of WMSH and the internal carotid blood flow (CaBF). Doppler ultrasound sonography is widely used for evaluation of CaBF. We analyzed the relationship between CBF, CaBF, and WMSH. The subjects had not suffered cerebral ischemic episodes although they had some risk factors for stroke. They received MRI and were classified into three groups, i.e. mild, moderate, and severe WMSH. The % stenosis of the internal carotid artery (ICA) was measured with angiography. Doppler sonography was used to measure the mean bilateral CaBF. The oxygen-15 steady-state technique and PET (positron emission tomography) were used to measure CBF. There were significant correlations between the % stenosis of ICA and the ipsilateral CaBF and between the % stenosis of ICA and hemispheric CBF. There was a significant relationship between CBF and CaBF in the severe WMSH group, remaining significant after partialling out of the effects of the % stenosis. This indicated that an atherosclerotic change of the cerebral artery occurred in a way that carotid vascular resistence and cerebrovascular resistence were 'proportional'.     

Noninvasive assessment of cerebral collateral blood supply through the ophthalmic artery

We assessed the potential of 2-MHz pulsed-wave transorbital Doppler ultrasonography to delineate the role of the ophthalmic artery as a source of collateral cerebral blood supply by comparing oculopneumoplethysmography, transorbital Doppler ultrasonography, periorbital continuous-wave Doppler ultrasonography, and transcranial Doppler ultrasonography in 25 patients with unilateral internal carotid artery occlusion and five controls with 10 normal internal carotid arteries. Systolic ophthalmic artery blood velocity was reduced ipsilateral to an internal carotid artery occlusion (38.2 +/- 10.2 cm/sec) compared with the contralateral and control velocities (46.0 +/- 10.3 and 47.5 +/- 6.8 cm/sec, respectively; p less than 0.05). Ophthalmic systolic pressure measured by oculopneumoplethysmography was 94.7 +/- 13.2 mm Hg ipsilateral to an internal carotid artery occlusion compared with 108.4 +/- 15.3 mm Hg on the contralateral side (p less than 0.01). Transorbital and periorbital Doppler ultrasonography detected reversed ophthalmic artery blood flow ipsilateral to an internal carotid artery occlusion in 44.0% and 40.0% of the patients, respectively. Systolic middle cerebral artery blood velocity was 55.2 +/- 22.3 cm/sec ipsilateral to an internal carotid artery occlusion compared with 79.4 +/- 23.5 cm/sec on the contralateral side (p less than 0.05) and 101.2 +/- 18.9 cm/sec in the controls (p less than 0.05). Reversed ophthalmic artery blood flow was associated with a low middle cerebral artery blood velocity and lack of major intracerebral collaterals. Transorbital Doppler ultrasonography permits noninvasive evaluation of the ophthalmic artery.(ABSTRACT TRUNCATED AT 250 WORDS)     

急性脑梗死散在和单一弥散加权成像病损与其供血动脉狭窄的关系

目的 探讨急性脑梗死弥散加权磁共振成像(DWI)上大脑中动脉(MCA)供血区散在性或单一性缺血性病损与其脑供血动脉狭窄或闭塞的关系.方法 回顾性分析73例连续积累的DWI显示一侧MCA供血区脑梗死的病例,入组病例均排除心源性栓塞性脑梗死,所有患者均在发病24 h内进行MRI和MRA等检查,7例患者并进行DSA.采用DWI急性缺血性病损分类方法 分为散在病损组和单一病损组,比较两组的病灶同侧MCA、颈内动脉(ICA)颅内段和颅外段狭窄或闭塞的发生率.结果 散在病损组42例,单一病损组31例.在病损同侧ICA颅外段和MCA闭塞或重度狭窄方面两组差异有统计学意义(28.6%与0,x2=10.6,P=0.001).在病损同侧ICA颅内段并MCA轻中度狭窄方面,两组间差异具有统计学意义(31.0%与9.7%,x2=4.717,P=0.03).散在病损与MCA和(或)ICA严重或多发狭窄呈正相关(OR值为13.7,95%CI:3.6～52.5).在MRA或DSA未发现颅内外大血管狭窄方面,两组间差异具有统计学意义(11.9%与32.3%,x2=4.526,P=0.033).散在病损组与无明显血管狭窄呈负相关(OR值为0.284,95%CI:0.09～0.94).结论 (1)脑梗死急性期DWI显示的MCA区散在性病损患者,MCA和ICA狭窄、甚至闭塞的可能性较大,以ICA颅外段闭塞较为常见;(2)DWI显示单一病损时提示脑供血动脉狭窄程度较轻,范围较局限,小血管病变的可能性相对较高,很少为严重的ICA颅外段狭窄或闭塞.

Abstract：

Objective To investigate the relationship between scattered or single lesion of acute cerebral infarction in middle cerebral artery territory on diffusion-weighted imaging (DWI) and stenosis of middle cerebral artery (MCA) or internal carotid artery (ICA). Methods With exclusion of cardioembolism, 73 consecutive patients with acute cerebral infarction of the unilateral MCA territory on DWI were analyzed. All patients got magnetic resonance imaging (MRI) and angiography (MRA) within 24 hours after onset, and 7 patients also had digital subtraction angiography (DSA). The patients were classified into single lesion group or scattered lesions group according to the DWI findings. The incidence of stenosis or occlusion of ipsolateral MCA, intracranial and extracranial ICA were compared between the two groups. Results 42 patients had scattered lesions and 31 patients had single lesion. The scattered-lesions group had a high incidence of ipsilateral extracranial ICA or MCA occlusion or severe stenosis ( 25.6%versus 0, x2 = 10.6, P = 0.001 ) and a high incidence of ipsilateral intracranial ICA or MCA moderate or mild stenosis (31.0% versus 9.7% ,x2 =4.717, P =0.03 ). A positive correlation was found between the scattered lesions and severe or multifocal stenosis of ipsilateral ICA and MCA ( OR: 13.7, 95% CI: 3.6 to 52.5). There was a low incidence of absence of extra- and intracranial stenosis on MRA or DSA in the scattered-lesions group ( 11.9% versus 32.3%, x2= 4.526, P = 0.033 ). A negative correlation was found between the scattered lesions and absence of large-artery stenosis ( OR: 0.284, 95% CI: 0.09 to 0.94).Conclusions ( 1 ) Patients with acute cerebral infarction and scattered lesions on DWI were more likely to suffer from stenosis or occlusion of ICA or MCA, especially over the extracranial ICA. (2) Patients with single lesion were less likely to have severe or multiple stenosis of MCA and ICA, indicating the relevance of small-vessel pathogenesis.     

A comparison of cerebral hemodynamic parameters between transient monocular blindness patients, transient ischemic attack patients and control subjects

PURPOSE: To assess whether patients with transient monocular blindness (TMB) and patients with hemispheric transient ischemic attacks (hTIA) differ from each other with respect to cerebral hemodynamic parameters. METHODS: Seventeen TMB patients and 23 hTIA patients with a moderate to severe stenosis or an occlusion of the internal carotid artery (ICA) underwent magnetic resonance (MR) angiography, (1)H MR spectroscopy and transcranial Doppler sonography. Thirty-one control subjects were investigated to obtain reference values for the MR investigations. Quantitative flow was measured in the ICAs, the basilar artery and the middle cerebral arteries (MCA). Metabolic changes in the MCA territory were studied by assessing N-acetyl-aspartate (NAA)/choline ratios and prevalences of lactate. The prevalence of collateral flow was assessed in the circle of Willis and the ophthalmic arteries. The vasomotor reactivity was studied by measuring the CO(2) reactivity of the MCA territories. RESULTS: Quantitative flow in the cerebropetal arteries and the MCAs did not differ between TMB patients and hTIA patients. Also patterns of collateral flow, prevalence of lactate and CO(2) reactivity were similar. The mean ipsilateral NAA/choline ratio was lower in hTIA patients compared with TMB patients (p < 0.01), and was predominantly correlated with symptomatology (p < 0.01), i.e. whether patients had TMB or hTIA, and not with ipsilateral MCA flow (p = 0.2) or ipsilateral CO(2) reactivity (p = 0.7). CONCLUSION: The results of this study indicate that there are no cerebral hemodynamic differences between TMB patients and hTIA patients. It is therefore unlikely that hemodynamic factors account for differences in clinical characteristics between the two patient groups.     

The formation and regression of a flow-related cerebral artery aneurysm

The authors report a patient with an aneurysm of the right cerebral posterior communicating artery (PCoA) developing after thrombotic pseudo-occlusion of the right internal carotid artery (ICA). The aneurysm regressed spontaneously subsequent to ipsilateral ICA endarterectomy and reversal of blood flow in the PCoA. The formation and regression of the aneurysm was well documented by repeat cerebral digital subtraction angiography studies, computed tomography and magnetic resonance imaging. The authors conclude that the formation and regression of this 'flow-related' aneurysm was associated with hemodynamic changes in blood flow of the right PCoA and the right ICA.     

Quantitative Volumetry in Patients With Carotid Disease—Effects of Acetazolamide

The intracranial effects of acetazolamide on flow velocities can be monitored noninvasively by transcranial Doppler (TCD) sonography. Extracranial volume flow changes can now reliably be measured with color duplex M-mode systems. The authors tested the volumetric effects of acetazolamide in patients with high-grade unilateral carotid disease to quantify the amount of flow changes. Patients in group 1 had a high-grade > 70% internal carotid artery (ICA) stenosis, without collateral flow through the ophthalmic artery (OA). Patients with occluded ICA were included in group 2 (patent OA collateralization) or group 3 (no OA collateralization) (n = 6 per group). In group 1, common carotid artery (CCA) volume flow in the stenotic (normal contralateral) side increased from 271 (388) ml/min by 52 (54%) with 1 g aceta-zolamide intravenously. Simultaneously, middle cerebral artery (MCA) flow velocities increased from 54 (56) cm/s by 47 (53%). In group 2, extracranial volume flow increased from 166 (444) ml/min by 19 (52)%. MCA flow velocities increased from 43 (65) cm/s by 13 (30)%. In group 3, volume flow increased from 159 (467) ml/min by 2 (46)%. Intracranial flow velocities rose from 49 (54) cm/s by 27 (41)%. Volume flow data showed the expected decline in patients with high-grade ICA stenosis and even more pronounced in patients with occlusion of the vessel. Cerebral reserve capacity was less sufficient in patients with a patent OA, despite an additional supply of 30 ml/min, indicating a hemodynamically critical situation.     

Transcranial Doppler Markers of Diffusion-Perfusion Mismatch

BACKGROUND AND PURPOSE: During the evaluation of acute ischemic stroke with diffusion- and perfusion-weighted magnetic resonance imaging (DWI and PWI, respectively), the presence of salvageable brain tissue is suggested by the occurrence of a perfusion-diffusion "mismatch." DWI and PWI, however, are not universally available and have inherent inconveniences, which justify a search for practical diagnostic alternatives. The purpose of this study is to investigate whether there are transcranial Doppler (TCD) markers of mismatch. METHODS: Retrospective analysis of 22 patients with acute ischemic stroke affecting the middle cerebral artery (MCA) territory, who had a TCD performed within 24 hours of magnetic resonance imaging (MRI) with DWI and PWI. RESULTS: MRI and TCD were performed on average 10.8 +/- 9.2 hours apart. Time from symptom onset to MRI and TCD completion were 1.6 +/- 1.6 and 2 +/- 1.9 days, respectively. MCA and intracranial internal carotid artery (ICA) cerebral blood flow velocity (CBFV) asymmetry, together with a large ICA-to-MCA gradient, were associated with the presence of mismatch. The combined use of 2 TCD parameters (MCA CBFV asymmetry of > or = 30% and ICA-to-MCA gradient > or = 20 cm/sec) had a sensitivity of 75%, specificity of 80%, positive predictive value of 82%, and negative predictive value of 73% at detecting mismatch cases. CONCLUSIONS: Diffusion-perfusion mismatch appears to be associated with interhemispheric asymmetry between MCA and ICA CBFVs, and a large CBFV gradient between the ICA and MCA on the affected side. Prospective studies are required to verify these observations and to determine whether TCD can be used to follow patients with mismatch.     

Non-invasive diagnosis of internal carotid artery dissections.

Arteriography is thought to be mandatory for the diagnosis of internal carotid artery (ICA) dissection. With the introduction of transcranial Doppler sonography (TCD) and magnetic resonance imaging (MRI), however, this is no longer the case. In 13 consecutive patients with ICA dissections the diagnosis was made by means of non-invasive tests including extracranial and transcranial Doppler sonography, contrast enhanced computed tomography (ceCT), and, in five patients, MRI. Intra-arterial digital subtraction angiography used as the gold standard in all cases was confirmative. Extracranial and transcranial ultrasound findings indicative of the diagnosis could be identified. MRI directly demonstrated the intramural haematoma and the false lumen of the dissected artery. These non-invasive techniques also allowed for repetitive follow up examinations. They were, however, unable to demonstrate false aneurysms in the chronic state. Results show that the diagnosis of carotid dissection can be made by means of cerebrovascular ultrasound and MRI.