Prediction of symptomatic vasospasm after subarachnoid hemorrhage by rapidly increasing transcranial Doppler velocity and cerebral blood flow changes.

BACKGROUND AND PURPOSE: Increased transcranial Doppler velocities and regional cerebral perfusion defects have been well demonstrated in patients with subarachnoid hemorrhage, but the clinical significance of these changes has not been clearly defined, particularly in the presymptomatic stage of cerebral vasospasm. We have tested the hypothesis that a rapid, massive rise in Doppler velocity denotes progressive vasospasm by relating Doppler velocity increases to regional cerebral blood flow changes and to the subsequent clinical course. METHODS: Serial transcranial Doppler sonography was performed in 121 patients; 20 of these patients were selected for blood flow mapping on the basis of rapid increases (greater than 50 cm/sec/24 hr) in blood flow velocity. Cerebral blood flow was mapped by single-photon emission computed tomography using technetium-99m hexamethylpropyleneamine oxime. RESULTS: Ten of 15 patients studied before the onset of any deficit subsequently developed a focal neurological abnormality. In 14 of these 15 patients, and in a further five in which single-photon emission computed tomography was performed after the onset of a delayed neurological deficit, perfusion patterns were abnormal and correlated with sites of increased Doppler velocities. Four patients had zones of cerebral hypoperfusion but did not develop neurological deficit. CONCLUSIONS: Transcranial Doppler measurements can assist in identifying patients at risk of delayed ischemic deficit. Selection of patients for regional cerebral blood flow mapping studies and for prophylactic anti-ischemic therapy may be considered on this basis.     

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.     

Transdermal nitroglycerin in patients with subarachnoid hemorrhage

Delayed ischemic neurological deficit (DIND) following cerebral vasospasm remains a cause for high morbidity and mortality in patients with subarachnoid hemorrhage (SAH). There is experimental and clinical evidence of positive effects of nitric oxide (NO) donors on cerebral vasospasm. We therefore analysed the effect of transdermal nitroglycerin in patients with SAH measuring transcranial Doppler velocities (TCD), cerebral blood flow (CBF) and DIND. Nitroglycerin was used in a target dose of 14 microg/kg/h. TCD assessment was performed daily. CBF measurements were done using the perfusion CT-technique. Blood pressure, volume intake and vasopressor administration, were registered. Nine patients were randomly assigned either to the nitroglycerin group (N-group) and eight patients in the control group (C-group). Mean TCD values in the extracranial portion of the internal carotid artery (ICA) were lower in the N-group (p<0.005). Mean TCD in the middle cerebral arteries (MCA) showed no difference. The Lindegaard ratio was higher in the N-group (p<0.04). CBF in the N-group was higher than in the C-group (p<0.03). Even though nitroglycerin reduces blood pressure and lowers ICA TCD-values and increases the Lindegaard ratio, a higher CBF was measured in the N-group. Thus, nitroglycerin influences the cerebral vascular tone and increases CBF. SAH therapy with nitroglycerin is possible without increasing the risk of DIND. The exact timing of onset, duration and reduction of nitroglycerin administration in respect to the appearance of vasospasm may have a strong impact on the success of such a therapy.     

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.     

Cerebral vasospasm and delayed ischaemic deficit following elective aneurysm clipping

Although common after subarachnoid haemorrhage, cerebral vasospasm (CVS) and delayed ischaemic neurological deficit (DIND) rarely occur following elective clipping of unruptured aneurysms. The onset of this complication is variable and its pathophysiology is poorly understood. We report two patients with CVS associated with DIND following unruptured aneurysmal clipping. The literature is reviewed and the potential mechanisms in the context of patient presentations are discussed. A woman aged 53 and a man aged 70 were treated with elective clipping of unruptured middle cerebral artery aneurysms, the older patient also having an anterior communicating artery aneurysm clipped. The operations were uncomplicated with no intra-operative bleeding, no retraction, no contusion, no middle cerebral artery (MCA) temporary clipping, and no intra-operative rupture. Routine post-operative CT scan and CT angiogram showed that in both patients the aneurysms were excluded from the circulation and there was no perioperative subarachnoid blood. Both patients had no neurological deficit post-operatively, but on day 2 developed DIND and vasospasm of the MCA. Both patients had angiographic improvement with intra-arterial verapamil treatment. In one patient, this was done promptly and the patient made a complete recovery, but in the other, the diagnosis was delayed for more than 24 hours and the patient had residual hemiparesis and dysphasia due to MCA territory infarction. CVS and DIND following treatment of unruptured aneurysms is a very rare event. However, clinicians should be vigilant as prompt diagnosis and management is required to minimise the risk of cerebral infarction and poor outcome.     

Transcranial color Doppler sonography (TCCD) in the diagnosis of vasospasm in the middle cerebral artery. Evaluation of TCCD diagnostic effectiveness by means of receiver operating characteristics curve (ROC) analysis

Transcranial Doppler sonography is commonly used for diagnosis of cerebral vasospasm. However, the overall diagnostic performance of this method in detection of arterial narrowing has not been established. Blood velocity threshold, diagnostic for vasospasm, has been proposed for conventional, "blind" transcranial Doppler sonography (TCD). Nevertheless it cannot be used for transcranial color Doppler sonography (TCCD), because in this method the obtained blood velocities in the major cerebral arteries are higher than are in TCD. The aim of this study was to estimate the accuracy of transcranial color Doppler sonography in detection of middle cerebral artery (MCA) narrowing by means of receiver operating characteristic curve analysis (ROC). One hundred thirty four patients were studied with TCCD immediately before cerebral angiography. There were 75 men and 59 women, age range from 18 to 74 years, mean age 49 years. Of the 268 MCAs examined, 227 arteries were finally included in the construction of the ROC curve. Angiographic vasospasm was graded as none, mild (equal to or less than 25% of vessel caliber reduction--16 patients) and moderate-to-severe (more than 25% of vessel caliber reduction--29 patients). The overall diagnostic performance of transcranial color Doppler sonography in the detection of moderate-to-severe vasospasm of middle cerebral artery was found to be very high. The value of associated area under the ROC curve was 0.94. The value of this area for all vasospasms was 0.85, and this indicates good accuracy of a test. The best performing TCCD parameter for the detection of MCA narrowing was revealed to be peak-systolic velocity. The optimal trade-off between sensitivity and specificity was achieved with a peak systolic velocity of 182 cm/s. Therefore this velocity threshold is proposed as most universal for the diagnosis of vasospasm in the middle cerebral artery.     

动脉瘤术后血管痉挛的综合治疗(附284例报告)

目的总结动脉瘤手术后血管痉挛及延迟性缺血性神经功能障碍(DIND)的防治经验。方法回顾性分析284例接受颅内动脉瘤夹闭术病人的临床资料,对颅多普勒超声(TCD)的结果与DIND的发生情况进行统计分析。结果137例病人手术后发生血管痉挛,79例发生DIND。TCD所示血流速度与DIND的发生有密切的相关关系。经治疗,62例DIND病人(78.5%)症状消失。病死率2.5%。结论血管痉挛是导致DIND的主要因素,个体化的综合治疗能明显提高疗效。     

Diagnosis of middle cerebral artery spasm by determination of flow velocity and the Lindegaard index with transcranial color Doppler sonography

BACKGROUND AND PURPOSE: Recent reports have demonstrated the high utility of transcranial color-coded duplex sonography (TCCS) in the diagnosis of advanced spasm of the middle cerebral artery, whereas its accuracy in the diagnosis of mild vasospasm is reported to be lower. Relation of blood flow velocity in the middle cerebral artery (MCA) to that in the extracranial internal carotid artery (VMCA/VICA index) is recommended as being helpful in the diagnosis of vasospasm (the so called Lindegaard Index). Nevertheless, the exact diagnostic value of this index using the TCCS method remains to be established. The purpose of this study is to estimate the accuracy of TCCS in the diagnosis of MCA vasospasm, as based on the VMCA/VICA index. MATERIAL AND METHODS: The VMCA/VICA index was calculated in 195 patients (285 middle cerebral arteries) who were scheduled for cerebral arteriography. The TCCS study and color-coded duplex sonography of the internal carotid arteries were performed immediately before arteriography. RESULTS: A mild grade of MCA spasm was diagnosed angiographically in 21, and moderate-to-severe spasm in 29 MCAs out of 285 successfully insonated arteries. Peak-systolic, mean and end-diastolic blood velocities were measured using transcranial color sonography in the MCA and related to the respective velocities in the ipsilateral extracranial internal carotid artery. Receiver-operating characteristic curves (ROC) were calculated for particular velocities and for the related VMCA/VICA indices. By comparison of the areas under the ROC curves it was shown that the use of the VMCA/VICA index does not improve the accuracy of TCCS in the diagnosis of advanced MCA spasm, whereas it improves accuracy in the diagnosis of mild vasospasm. In particular, accuracy can be improved by the use of the VMCA/VICA index based on the end-diastolic velocity. The optimal diagnostic threshold of the VMCA/VICA index was determined at 3.9. CONCLUSIONS: The use of VMCA/VICA index improves the accuracy of TCCS in the diagnosis of mild vasospasm of the middle cerebral artery.     

Correlations between cerebral arterial velocities, blood flow, and delayed ischemia after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Elevated middle cerebral erythrocyte velocities and tissue hypoperfusion have been correlated with delayed ischemia after subarachnoid hemorrhage, but few studies have compared serial arterial velocities with cerebral blood flow and neurological deficits. METHODS: Serial measurements of middle cerebral velocities, using transcranial Doppler ultrasonography, were performed in 34 patients after subarachnoid hemorrhage and correlated with cerebral blood flow, measured in 20 of the 34 using single-photon emission computed tomography with technetium-99m hexamethylpropylene amine oxime and neurological evidence of delayed ischemia. RESULTS: In 16 patients without delayed ischemia, eight had evidence of vasospasm (greater than 120 cm/sec), but only one of seven had hypoperfusion, suggesting that vasospasm might be more common than hypoperfusion in this group (p = 0.1). In 10 patients with delayed ischemia and a lateralizing deficit, both asymmetrical middle cerebral vasospasm (eight of nine with vasospasm) and hypoperfusion (six of six studied) were concordant with the clinically ischemic hemisphere (p less than 0.05). Vasospasm occurred with nonlateralized delayed ischemia in seven of eight patients and with hypoperfusion in five of six, affecting the anterior cerebral territory in three. CONCLUSIONS: Concordant vasospasm and hypoperfusion were most often present in patients with delayed ischemia and lateralizing neurological deficits. Discordant results reflect inherent limitations and the different levels of the circulation monitored by the two techniques.     

Demonstration of giant MCA aneurysm by transcranial duplex sonography and color Doppler imaging

Transcranial color Doppler sonography is a new diagnostic technique which allows real-time, colorcoded imaging of basal cerebral arteries, with simultaneous demonstration of parenchymal structures in the B-mode scan. With this technique we were able nonivasively to show a giant fusiform aneurysm of the middle cerebral artery (MCA) in an 11-year-old boy. Transcranial color Doppler sonography through the intact temporal bone demonstrated the size and location of the aneurysm and provided real-time imaging of the pulsating intra-aneurysmal flow. Additionally, duplex sonographic measurements of intravascular flow velocities within the aneurysm and the feeding and draining artery were possible. Postoperatively, patency of the MCA with reduced flow velocities after excision of the aneurysm could be shown. This is the first transcranial color Doppler report in a patient with an intracerebral aneurysm. In our opinion, transcranial color Doppler sonography offers new diagnostic possibilities in patients with cerebrovascular disorders.     

Transcranial Doppler findings during balloon test occlusion of the internal carotid artery.

The authors performed transcranial Doppler ultrasonography (TCD) during internal carotid artery (ICA) balloon test occlusion (BTO) and observed changes in mean flow velocity (Vm) in the middle cerebral artery (MCA), and pulsatility index (PI) while monitoring the stump pressure (Sp) of the internal carotid artery (ICA), and neurologic findings. A group of 17 patients requiring possible temporary or permanent occlusion of the ICA in the course of planned procedures first underwent BTO. A patient who either developed neurologic changes or maintained less than 60% of preocclusion Sp or Vm in the ipsilateral MCA during BTO was considered to have a positive test. Eleven patients had negative results, while in six patients, tests were positive. Mean flow velocity showed a decrease after occlusion in all cases but not to a remarkable extent in some patients. Stump pressure decreased in all negative cases after balloon inflation and than tended to increase progressively during 15 minutes of BTO. Pulsatility index tended to decrease gradually during BTO in all negative patients. However, in positive cases, PI and Sp fell steeply. Only one positive case had a neurologic symptom of severe headache. The decreased PI in the MCA reflected autoregulatory dilation of cerebral vessels to compensate for decreased absolute cerebral blood volume following ICA occlusion. Changes in PI are a good indicator for evaluating blood flow during BTO.     

The relation between cerebral blood flow velocities as measured by TCD and the incidence of delayed ischemic deficits. A prospective study after subarachnoid hemorrhage

Patients (n = 127) with aneurysmal subarachnoid hemorrhage (SAH) were examined by transcranial Doppler ultrasonography (TCD) in a prospective study to follow the time course of the posthemorrhagic blood flow velocity in both the middle cerebral artery (MCA) and in the anterior cerebral artery (ACA). Results were analysed to reveal their relationship and predictive use with respect to the occurrence of delayed ischemic deficits. Mean flow velocities (MFV) higher than 120 cm sec(-1) in MCA and 90 cm sec(-1) in ACA were interpreted as indicative for significant vasospasm. In 20 of our 127 patients (16%) a delayed ischemic deficit (DID) was subsequently diagnosed clinically (DID+ group). Patients in the DID+ group can be characterized as those individuals who presented early during the observation period post-SAH with highest values of MFV, a faster increase and longer persistence of pathologically elevated MFV-values (exceeding 120 cm sec(-1) in MCA and 90 cm sec(-1) in ACA). They also show a greater difference in MFV-values if one compares the operated to the nonoperated side. Differences in MFV-values obtained in MCA or ACA were statistically significant (p < 0.05) for DID+ and DID- patients. The daily maximal increase of MFV was found between days 9 and 11 after SAH. In the DID+ group, the maximal MFV was 181 +/- 26 cm sec(-1) in MCA and 119 +/- 14 cm sec(-1) in ACA. In contrast to this, patients in the DID- group were found to present with MFV of 138 +/- 11 cm sec(-1) in MCA and 100 +/- 7 cm sec(-1) in ACA respectively. Delayed ischemic deficits appeared three times more often in DID+ patients than in patients with MFV < 120 cm sec(-1), if they showed a MFV > 120 cm sec(-1) in MCA. If pathological values were obtained in ACA, this ratio increases to about four times, if DID + patients presented with MFV > 90 cm sec(-1) versus patients with MFV < 90 cm sec(-1). Daily monitoring of vasospasm using TCD examination is thus helpful to identify patients at high risk for delayed ischemic deficits. This should allow us to implement further preventive treatment regimens.     

Cerebral Vasospasm with Delayed Ischemic Neurologic Deficit after Unruptured Aneurysm Surgery : Report of Two Cases and Review of the Literature

Symptomatic cerebral vasospasm (CVS) and delayed ischemic neurologic deficit (DIND) after unruptured aneurysm surgery are extremely rare. Its onset timing is variable, and its mechanisms are unclear. We report two cases of CVS with DIND after unruptured aneurysm surgery and review the literature regarding potential mechanisms. The first case is a 51-year-old woman with non-hemorrhagic vasospasm after unruptured left anterior communicating artery aneurysm surgery. She presented with delayed vasospasm on postoperative day 14. The second case is a 45-year-old woman who suffered from oculomotor nerve palsy caused by an unruptured posterior communicatig artery (PCoA) aneurysm. DIND with non-hemorrhagic vasospasm developed on postoperative day 12. To our knowledge, this is the first report of symptomatic CVS with oculomotor nerve palsy following unruptured PCoA aneurysm surgery. CVS with DIND after unruptured aneurysm surgery is very rare and can be triggered by multiple mechanisms, such as hemorrhage, mechanical stress to the arterial wall, or the trigemino-cerebrovascular system. For unruptured aneurysm surgery, although it is rare, careful observation and treatments can be needed for postoperative CVS with DIND.     

Learning Vector Quantization Neural Networks Improve Accuracy of Transcranial Color-coded Duplex Sonography in Detection of Middle Cerebral Artery Spasm—Preliminary Report

To determine the performance of an artificial neural network in transcranial color-coded duplex sonography (TCCS) diagnosis of middle cerebral artery (MCA) spasm. TCCS was prospectively acquired within 2 h prior to routine cerebral angiography in 100 consecutive patients (54M:46F, median age 50 years). Angiographic MCA vasospasm was classified as mild (<25% of vessel caliber reduction), moderate (25–50%), or severe (>50%). A Learning Vector Quantization neural network classified MCA spasm based on TCCS peak-systolic, mean, and end-diastolic velocity data. During a four-class discrimination task, accurate classification by the network ranged from 64.9% to 72.3%, depending on the number of neurons in the Kohonen layer. Accurate classification of vasospasm ranged from 79.6% to 87.6%, with an accuracy of 84.7% to 92.1% for the detection of moderate-to-severe vasospasm. An artificial neural network may increase the accuracy of TCCS in diagnosis of MCA spasm.     

Emotional processing in Parkinson's disease. A study using functional transcranial doppler sonography

This study evaluated the use of transcranial Doppler ultrasonography for detecting selective changes in cerebral blood flow velocity during emotional processes. The aim was to investigate the possibility of obtaining functional information on the neuropsychology of emotions in patients with Parkinson's disease (PD). For this reason, blood flow velocity changes were investigated in both middle cerebral arteries (MCA) during a rest condition and when viewing non emotional (tasks 1 and 3) and emotional (task 2) slide sequences. The study included 12 PD patients and 12 healthy subjects. All patients were in treatment with levodopa or dopamine agonist. Investigation of PD patients was performed during an on-phase. The three tasks produced significantly different effects on the right and left side in the PD patients compared with the control group. During the two non emotion-related tasks the increase of mean flow velocity (MFV) compared with the basal values was similar in the two middle cerebral arteries in both groups [(PD Patients: Task 1: left MCA = 3.95 % 2.2, Right MCA = 4.33 % ± 2.3, Task 3: left MCA = 3.04 % ± 1.9, Right MCA = 2.71 % ± 2.2) (control group: Task 1: left MCA = 4.57 % ± 1.4, Right MCA = 4.46 % ± 1.7, Task 3: left MCA = 2.32 % ± 0.9, Right MCA = 2.52 % ± 1.2)] The negative emotional task was accompanied by a significantly higher increase in the right (10.53 % ± 3.2) than in the left middle cerebral artery (4.52 % ± 1.51) only in the control group. The PD patients showed a bilateral and symmetrical increase of MFV (left MCA = 4.28 % ± 2.3 and right MCA 5.77 % ±3.8). To determine whether there was a dysfunction in cerebrovascular reactivity and a deficit in the ability to activate both hemispheres in response to non emotion-related stimuli in the PD patients, the protocol study included a cerebrovascular reactivity test to apnea, a motor task (thumb-to-finger opposition), a cognitive task (word fluency and visual discrimination of objects), performed by both patients and controls. The pattern of MFV changes during these tasks was not statistically significantly different in the two experimental groups. In order to evaluate the possible influence of drug treatment on cerebrovascular reactivity, seven patients were also evaluated during an off-phase, after a 48-hour wash-out period. Changes in MFV during every task were similar to that observed during the on-phase. These findings show the possibility of obtaining specific functional information from bilateral transcranial Doppler and suggest the selective and specific deficit of PD patients in emotional processing. Received: 23 July 2001 Received in revised form: 28 January 2002 Accepted: 1 February 2002     

Three-dimensional transcranial Doppler in acute ischemic stroke in the territory of the middle cerebral artery: clinical and CT correlation.

We studied 34 patients with acute ischemic stroke in the territory of the middle cerebral artery (MCA) by three-dimensional transcranial Doppler (TCD-3D). The parameters analyzed were: mean blood flow velocity, systolic and diastolic velocities; indices of pulsatility, hemisphere asymmetry and pulsatility transmission. Of the 34 patients 11 presented marked slowing of flow velocity in the MCA on the infarct side with an asymmetry index (AI) of over 40%, 8 patients with slightly reduced flow velocity in the MCA and an AI of 25-40%, 2 patients in whom there was indirect evidence of collateral circulations in the anterior cerebral artery distribution together with slowing of MCA flow; 5 patients had stenosis of the MCA, 9 patients showed no alterations of the Doppler parameters. The correlation between neurological symptom pattern and AI was significant (r = 0.76). Noninvasive, easy to perform, performable at once and reliable, TCD-3D is a great improvement on traditional transcranial Doppler and is especially useful in assessing the hemodynamics of the cerebral circulation in ischemic stroke.     

经颅彩色多功超声诊断脑动脉狭窄与脑血管造影的对比研究

目的 验证经颅彩色多功超声（TCCD）诊断大脑中动脉（MCA）狭窄的可靠性。方法 对168例行脑血管造影的脑血管病患者同时进行了TCCD检查。结果 脑血管造影诊断狭窄的MCA18条,TCCD检出15条有狭窄。造影未证实有狭窄的MCA血管中,TCCD检出2条有狭窄。TCCD诊断MCA狭窄的敏感性和特异性为83％和88％。结论 TCCD诊断MCA狭窄准确性较好,优于经颅多普勒（TCD）。     

B-waves in healthy persons

The objective of this study was to determine, whether 0.5-2/min oscillations in intracranial pressure ('B-waves') are a physiological phenomenon. In a group of 5 patients 0.5-2/min oscillations of ventricular pressure simultaneous with oscillations in the middle cerebral artery (MCA) flow velocity, as assessed by transcranial Doppler sonography, were observed. Similar oscillations in MCA blood flow velocity were demonstrated in 8 out of 10 healthy subjects with an amplitude of about 10% of the mean flow velocity. We speculate that oscillations both in ventricular pressure and middle cerebral artery blood flow velocity are caused by rhythmic diameter changes of cerebral vessels with concomitant cerebral blood volume oscillations. Our data support the suggestion that B-waves may be physiological.     

Three-dimensional transcranial Doppler in acute ischemic stroke in the territory of the middle cerebral artery: Clinical and CT correlation

We studied 34 patients with acute ischeiic stroke in the territory of the middle cerebral artery (MCA) by three-dimensional transcranial Doppler (TCD-3D). The parameters analyzed were: mean blood flow velocity, systolic and diastolic velocities; indices of pulsatility, hemisphere asymmetry and pulsatility transmission. Of the 34 patients 11 presented marked slowing of flow velocity in the MCA on the infarct side with an asymmetry index (AI) of over 40%, 8 patients with slightly reduced flow velocity in the MCA and an AI of 25–40%, 2 patients in whom there was indirect evidence of collateral circulations in the anterior cerebral artery distribution together with slowing of MCA flow; 5 patients had stenosis of the MCA, 9 patients showed no alterations of the Doppler parameters. The correlation between neurological symptom pattern and AI was significant (r=0.76). Noninvasive, easy to perform, performable at once and reliable, TCD-3D is a great improvement on traditional transcranial Doppler and is especially useful in assessing the hemodynamics of the cerebral circulation in ischemic stroke.