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

Abstract

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 MFVvalues 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. [Neurol Res 2002; 24: 582-592]     

The influence of ruptured cerebral aneurysm localization on the blood flow velocity evaluated by transcranial Doppler ultrasonography

The relationship between changes of blood flow velocities in cerebral arteries measured by transcranial Doppler ultrasonography and aneurysm localization was investigated in a group of 165 patients after aneurysmal subarachnoid hemorrhage (SAH). Mean blood flow velocities (MFV) in the middle cerebral artery (MCA) and anterior cerebral artery (ACA) were registered. In patients with aneurysm of internal carotid artery and MCA (group A) statistically significant higher values of MFV from the 1st to the 5th day and on the 12th, 13th, 14th, 15th, and 19th day after SAH were found compared to patients with aneurysm of the anterior communicating artery, ACA, and pericallosal artery (group B). Pathological values of MFV exceeding 120 cm sec-1 in MCA were registered during 14 days in group A and during eight days in group B. Blood flow velocities in ACA were statistically significantly higher in group B on the 2nd, 7th, 9th and 11th day compared to group A. Pathological values of MFV exceeding 90 cm sec-1 in ACA were registered during nine days in both groups. MFV differences between group A and group B in 38 patients subjected to delayed surgery were not observed. The influence of aneurysm localization was observed between the 7th and 14th day after SAH. Critical MFV values for vasospasm in the MCA should be 120 cm sec-1 and in the ACA 90 cm sec-1.     

Early cerebral hemodynamic alternations in patients operated on the first, second and third day after aneurysmal subarachnoid hemorrhage

Surgery timing after aneurysmal subarachnoid hemorrhage (SAH) may influence the risk of vasospasm after early surgical procedure and is correlated with SAH extensiveness. A group consisting of 127 patients with aneurysmal SAH was studied. The changes of mean flow velocity (MFV) were measured in middle cerebral artery (MCA) and in anterior cerebral artery (ACA) by transcranial Doppler sonography (TCD) in three groups of patients divided according to the surgery timing (on the first, second and third day after SAH). Changes of MFV values in MCA and in ACA were similar in all groups. MFV values in the group of patients operated on the third day were the lowest and the pathologic values lasted for the shortest time. In patients with massive SAH (Fisher IV group) and mild SAH (Fisher II group), the lowest MFV values were observed, if patients were operated within 24 hours after SAH. In patients without SAH (Fisher I group), the MFV values were the lowest, if they were operated on the third day after SAH. In patients with severe SAH (Fisher III group), the lowest risk of vasospasm was observed, if they were operated on the second day after SAH; however, the highest risk was found in patients operated on the first day after SAH. Our study suggests: (1) in patients with severe SAH operated on the second day, the lowest risk of vasospasm was observed, and the highest risk of vasospasm was observed if those were operated on the first day; (2) the highest risk of vasospasm was observed in patients operated within 24 hours with mild and massive SAH and in patients without SAH operated on the third day after SAH.     

Vasospasm after SAH due to aneurysm rupture of the anterior circle of Willis: value of TCD monitoring

OBJECTIVE: The aim of this study was to verify the presence of angiographic vasospasm in patients with transcranial Doppler (TCD) of high velocities after subarachnoid hemorrhage (SAH). METHODS: Seven hundred and eighty-six cases admitted within 48 hours after SAH due to the rupture of anterior circulation aneurysm, were prospectively studied with TCD. In cases of TCD velocities higher than 120 cm/s (TCD vasospasm), the patient underwent a control angiography. Hunt-Hess and Fisher's grade on admission CT and location of the aneurysm were related to occurrence of TCD vasospasm. The increase in TCD velocities within 24 hours was calculated and related to the presence of cerebral ischemia on discharge CT, considering three groups of patients: Group A with an increase in velocities higher than 60%, Group B with an increase in velocities between 30 and 60%, and Group C with an increase in velocities lower than 30%. RESULTS: TCD vasospasm was observed in 216 patients (27%). In 97% of patients with TCD vasospasm on middle cerebral artery (MCA) and in 71% with TCD vasospasm on anterior cerebral artery (ACA), control angiography confirmed the vasospasm, with a significant lower diagnostic TCD predictivity of ACA spasm (chi2=28.204, p=0.000). The overall positive predictive value of TCD was 89%. There was no significant correlation of TCD vasospasm with clinical status on admission and location of the aneurysm, but a significant correlation between occurrence of TCD vasospasm and Fisher's grade (chi2=15.470, p=0.002) and between the increase rate in TCD velocities and cerebral ischemia (chi2=56.564, p=0.000). CONCLUSION: Our study shows a good correlation between TCD and angiography to detect vasospasm on MCA, but the correlation is low for ACA. TCD alone cannot discriminate different hemodynamic pathways after SAH.     

Detection of Intracranial Internal Carotid Artery and Middle Cerebral Artery Vasospasm Following Subarachnoid Hemorrhage

Little is known about the accuracy of transcranial Doppler (TCD) sonography in detecting intracranial internal carotid artery (IICA) and middle cerebral artery (MCA) vasospasm. TCD was performed in 49 patients with subarachnoid hemorrhage to evaluate 90 IICAs and 87 MCAs during the vasospasm period. When a mean velocity of at least 90 cm/sec was used to indicate IICA vasospasm, there were 11 positive, 42 negative, 4 false-positive, and 33 false-negative results. Sensitivity was 25% and specificity was 93%. When a mean velocity of at least 120 cm/sec was used to indicate MCA vasospasm, there were 15 positive, 45 negative, 3 false-positive, and 24 false-negative results (15 operator errors). Sensitivity was 38.5% and specificity was 93.7%. When the diagnostic criterion was changed to at least 130 cm/sec, specificities were 100% (IICA) and 96% (MCA) and positive predictive values were 100% (IICA) and 87% (MCA). The authors conclude that TCD accurately detects IICA and MCA vasospasm when flow velocities are at least 130 cm/sec. However, its sensitivity may be underestimated and the importance of operator error, overestimated.     

Detection of Vasospasm by Transcranial Doppler Sonography

Little information exists on the utility of transcranial Doppler sonography (TCD) in detecting anterior (ACA) and posterior cerebral artery (PCA) vasospasm following subarachnoid hemorrhage. During the period at risk for vasospasm, 53 patients with subarachnoid hemorrhage who had technically adequate TCD performed within 24 hours of cerebral angiography, allowing evaluation of 87 ACAs and 84 PCAs, were studied. ACA and PCA vasospasm were defined by mean blood flow velocities of at least 120 cm/ sec and at least 90 em/sec, respectively. For detection of ACA vasospasm, sensitivity was 18% and specificity was 65%. For PCA vasospasm, sensitivity was 48% and specificity was 69%. False-positive findings for occlusion accounted for 12 (92 %) of 13 ACA false-positive results and 7 (37%) of 19 PCA false-positive results, and were most often due to anatomical factors and operator error or inexperience. After exclusion of both true-positive and false-positive findings for occlusion and changes in the diagnostic criterion to at least 130 cm/sec for ACA vasospasm and at least 110 cm/sec for PCA vasospasm, specificity improved for both types of vasospasms (100 and 93%, respectively). However, the sensitivity of TCD to detect ACA and PCA vasospasm is limited by a variety of anatomical, technical, and other factors. It is concluded that TCD is highly specific in detecting both ACA and PCA vasospasm in arteries that can be insonated.     

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.     

经颅多普勒监测蛛网膜下腔出血后脑血管痉挛的临床观察

目的总结应用经颅多普勒(TCD)监测蛛网膜下腔出血(SAH)后脑血管痉挛的临床价值。方法对2015-06—2016-05本院收治的78例SAH患者进行回顾性分析,均进行TCD监测,同时对患者进行数字减影血管造影(DSA)检查,观察各个时间段患者颅内血管血流速度变化,并以DSA检查结果作为标准判断TCD诊断颅内血管痉挛的价值。结果在7~10d时间段,患者的MCA、ACA、VA、BA血流速度达到峰值,后逐渐下降,颅内血管痉挛现象逐渐缓解;SAH患者MCA、ACA、VA、BA血流速度在7d、7~10d、10~14d三个时间段比较差异均具有统计学意义(P0.05);78例SAH患者,TCD诊断发生颅内血管痉挛59例,DSA诊断发生率颅内血管痉挛62例,TCD诊断SAH患者发生颅内血管痉挛的灵敏度为93.55%、特异度为93.75%、漏诊率为6.45%、误诊率为6.25%,TCD诊断颅内血管痉挛与DSA的一致性Kappa=0.816,P0.05。结论 TCD检查诊断SAH后出现颅内血管痉挛具有准确性高、无创等优点,值得临床推广应用。     

Blood flow velocities in middle cerebral artery branches after subarachnoid hemorrhage.

In a prospective study, 55 patients were examined by transcranial duplex sonography (TCCS) after subarachnoid hemorrhage (SAH) to determine whether additional transcranial duplex examination on the middle cerebral artery M2 segments would aid in the examination of the MCA stem segment. The mean blood flow velocities and pulsatility index were correlated to the occurrence of delayed ischemic neurologic deficits (DIND). Out of 47 patients included, 21 did not experience any delayed deficit (group I), 15 did (group II), and in 11 the extent to which vasospasm contributed to a neurologic deficit was unclear (group III). The highest blood flow velocity and the greatest increase of mean blood flow velocity on 1 day were significantly higher in groups II and III both in M1 and in M2. In 10 patients in group II, where the onset day of DIND was known exactly, Doppler data indicating ischemia before or at the time of DIND were observed in nine. In eight patients, Doppler of the MCA stem alone would have provided enough information to recognize the risk of symptomatic vasospasm; in one patient, only the M2 Doppler gave an indication of ischemic complication. Transcranial duplex sonography may provide additional information to TCD by accurate delineation of M1/M2 vasospasm and therefore may help plan cerebral angiography and neurointerventional treatment.     

Value of Transcranial Doppler,Perfusion-CT and Neurological Evaluation to Forecast Secondary Ischemia after Aneurysmal SAH

Introduction

This study was conducted to prospectively evaluate the diagnostic value of detailed neurological evaluation, transcranial Doppler sonography (TCD) and Perfusion-CT (PCT) to predict delayed vasospasm (DV) and delayed cerebral infarction (DCI) within the following 3 days in patients with aneurysmal subarachnoid hemorrhage (SAH).

Methods

A total of 61 patients with aneurysmal SAH were included in the study. All patients were amenable for neurological evaluation throughout the critical phase to develop secondary ischemia after SAH. The neurological status was assessed three times a day according to a detailed examination protocol. Mean flow velocities (MFV) in intracranial vessel trunks were measured daily by TCD. Native CT and PCT were routinely acquired at 3-day intervals and, in addition, whenever it was thought to be of diagnostic relevance. The predictive values of abnormal PCT and accelerations in TCD (MFV > 140 cm/s) to detect angiographic DV and DCI within the following 2 days were calculated and compared to the predictive value of delayed ischemic neurological deficits (DIND).

Results

The accuracy of TCD and PCT to predict DV or DCI was 0.65 and 0.63, respectively. In comparison, DIND predicted DV or DCI with an accuracy of 0.96. Pathological PCT findings had a higher sensitivity (0.93) and negative predictive value (0.98) than TCD (0.81 and 0.96).

Conclusion

Neurological assessment at close intervals is the most accurate parameter to detect DV and DCI in the following 3 days. However, DIND may not be reversible. The routine acquisition of PCT in addition to daily TCD examinations seems reasonable, particularly in patients who are not amenable to a detailed neurological examination since it has a higher sensitivity and negative predictive value than TCD and leaves a lower number of undetected cases of vasospasm and infarction.     

Reduction of ischemic sequelae following spontaneous subarachnoid hemorrhage: a double-blind, randomized comparison of enoxaparin versus placebo

BACKGROUND: Cerebral vasospasm, including its ischemic sequelae, remains a leading cause of death and disability following subarachnoid hemorrhage (SAH). This study was designed to evaluate whether the low-molecular-weight heparin (LMWH) enoxaparin reduces the occurrence of cerebral vasospasm and ischemia following spontaneous SAH. METHODS: A prospective, double-blind, randomized study was conducted in 120 consecutive patients with SAH (Hunt Hess Scale (HHS) I-III). Patients received one subcutaneous injection per day of either 20mg enoxaparin or placebo for 3 weeks following SAH. Efficacy endpoints were the occurrence of cerebral vasospasm, delayed ischemic deficit (DID), cerebral infarction, and overall outcome at 1 year following SAH. RESULTS: At 1-year follow-up, enoxaparin significantly reduced DID and cerebral infarction. Delayed ischemic deficit occurred in 8.8% of the enoxaparin group versus 66.7% of the placebo group (P<0.001), while 3.5% of vasospasm-related cerebral infarctions occurred in enoxaparin-treated patients and 28.3% in placebo-treated patients (P<0.001). Severe shunt-dependent hydrocephalus was significantly lower in the enoxaparin group (1.8% versus 16.7%; P=0.019). Compared with the placebo group, the enoxaparin group had fewer intracranial bleeding events and better overall outcomes at 1-year follow-up. Although there was potential bias as a result of patients in the placebo group being more severely affected (in terms of HHS), treatment with enoxaparin for 3 weeks improved long-term outcome following SAH. CONCLUSIONS: Enoxaparin is safe and effective in reducing cerebral vasospasm and ischemia following SAH (Hunt Hess grades I-III), resulting in a better long-term outcome for the patient.     

Derivation of Power M-Mode Transcranial Doppler Criteria for Angiographic Proven MCA Occlusion

BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies.     

Transcranial Doppler sonography evaluation of anterior cerebral artery hypoplasia or aplasia

BACKGROUND AND PURPOSE: Transcranial Doppler (TCD) sonography is useful to evaluate intracranial arteries, however, interpretation of the TCD results in anterior cerebral artery (ACA) is difficult because of hypoplasia or aplasia. We try to define useful TCD indices and cut-off values to determine the variations of ACA. METHODS: Consecutive patients who underwent TCD and magnetic resonance angiography (MRA) were included. Patients with cerebrovascular abnormality or inadequate temporal windows were excluded. ACA status was classified as normal (NL), hypoplasia (HP), and aplasia (AP) according to MRA. TCD indices of mean flow velocity (MFV), pulsatility index (PI), ACA/middle cerebral artery (MCA) flow velocity ratio (ACA/MCA FVR), and asymmetry index (AI) of ACA were blindly compared with MRA between three groups. RESULTS: Two hundred and forty-one patients were included, and 193 patients (80%) were classified as NL, 34 (14%) as HP and 14 (6%) as AP. MFV was significantly lower in HP and AP (p<0.001), however, PI and ACA/MCA FVR were not different. AI was significantly different between NL and HP (21.5% vs. 50.4%), NL and AP (21.5% vs. 105.2%) (p<0.001). CONCLUSIONS: MFV of ACA should be interpreted with caution for its frequent anatomical variations. AI is useful to differentiate hypoplasia and aplasia from normal ACA with optimal criteria.     

动脉瘤夹闭术可能缩短急性动脉瘤性蛛网膜下腔出血相关脑血管痉挛持续时间

目的   比较不同治疗方法对动脉瘤性蛛网膜下腔出血（aneurysmal subarachnoid hemorrhage,aSAH）后的血流动力学变化,并分析对aSAH后血管痉挛的影响。 方法  连续选取2008年4月～2009年10月首都医科大学附属北京天坛医院神经病学中心急诊入院的45例发病在72?h内的aSAH患者,收集基线资料、计算机断层扫描（computed tomography,CT）、经颅多普勒超声（transcranial Doppler,TCD）及90?d改良Rankin量表评分。根据患者接受的治疗分为保守组、填塞组和夹闭组。使用TCD连续测定14?d之内大脑中动脉及大脑前动脉血流速度,计算Lindegaard指数,比较3组的处理平均血流速度、Lindegaard指数及血管痉挛持续时间。 结果  大脑前动脉/大脑中动脉的平均血流速度及Lindegaard指数由高到低依次为保守组、夹闭组及填塞组［大脑前动脉：平均血流速度为（74.60±5.84）cm/s、（70.00±5.24）cm/s、（65.70±6.03）cm/s,P=0.0001;Lindegaard指数分别为3.87±0.32、3.82±0.31、3.65±0.36,P=0.006;大脑中动脉：平均血流速度分别为（101.2±9.1）cm/s、（87.0±6.2）cm/s、（76.2±9.2）cm/s,P=0.004;Lindegaard指数分别为5.50±0.65、4.15±0.46、3.81±0.55,P=0.005］。夹闭组患者脑血管痉挛持续时间较保守组短［（3.30±1.87）d vs?（7.29±2.23）d,P=0.035］。保守组患者90?d预后较差（P=0.028）。 结论  神经外科夹闭术和血管内动脉瘤填塞术均能缓解急性aSAH后脑血管痉挛的严重程度;外科夹闭术可缩短脑血管痉挛持续时间。     

Continual Transcranial Doppler in the Monitoring of Hemodynamic Change following Aneurysmal Subarachnoid Hemorrhage

Aims: To analyze and compare the value of different treatment methods for acute aneurysmal subarachnoid hemorrhage (aSAH)‐related vasospasm. Cerebral hemodynamic variables’ changes were evaluated by transcranial Doppler (TCD) in aSAH patients within 14 days after onset. Methods: Thirty aSAH patients were enrolled in the study within 72 h after onset. Baseline CT and TCD were used for assessment. Patients were divided into three groups according to SAH severity and patients’ discretion: nonsurgical group, endovascular coiling, and neurosurgical clipping. TCD hemodynamic parameters were measured and Lindegaard index was calculated daily from onset to 14th day after SAH. The group mean cerebral blood velocity (MBFV) and Lindegaard index were compared using repeated measures analysis of variance (reANOVA). Least Significant Difference (LSD) test was used for post hoc comparison. All 30 patients were followed for 90 days after onset for outcome assessment. Results: The values of MBFV and Lindegaard index of anterior cerebral artery (ACA)/middle cerebral artery (MCA) from high to low is nonsurgical group, clipping and coiling (ACA: P= 0.0001/P= 0.006; MCA: P= 0.243/P= 0.317). Conclusions: These results indicate that both neurosurgical clipping and endovascular coiling management may relieve the severity of cerebral vasospasm in acute aSAH.     

Sensitivity and specificity of transcranial Doppler ultrasonography in the diagnosis of vasospasm following subarachnoid hemorrhage

Vasospasm is the leading cause of death and disability in patients with aneurysmal subarachnoid hemorrhage (SAH). Transcranial Doppler ultrasonography (TCD) can detect the arterial narrowing noninvasively, but the sensitivity and specificity of this technique have not been reported in a population of patients with a high frequency of angiographic vasospasm. In this study, 34 consecutive patients with SAH undergoing angiography during the period of risk for vasospasm had technically adequate TCD examinations within 24 hours of the angiogram. Using a mean flow velocity of 120 cm/sec and above as indicative of vasospasm, TCD correctly detected angiographic vasospasm in 17 patients; there were no false positives. It correctly determined that 5 patients did not have vasospasm, whereas there were 12 false negatives. False negatives were frequently due to angiographic vasospasm involving vessels not assessable by TCD. The correlation between mean flow velocity and the angiographic residual lumen diameter of the middle cerebral artery was statistically significant. These data suggest that TCD is a highly specific (100%), but less sensitive (58.6%) test for the detection of angiographic vasospasm following SAH. Confirmatory angiography may be avoided if the TCD study is positive, but additional studies may be necessary if the clinical picture is suspicious and the TCD study is negative.     

Screening for Intracranial Stenosis With Transcranial Doppler: The Accuracy of Mean Flow Velocity Thresholds

BACKGROUND: Patients with 50% intracranial arterial stenosis may require more intensive therapies for stroke prevention. Transcranial Doppler (TCD) is a convenient noninvasive screen for intracranial stenosis. The accuracy of different mean flow velocity (MFV) thresholds for determining the degree of stenosis remains uncertain. METHODS: The authors prospectively compared the accuracy of TCD criteria and MFV thresholds to magnetic resonance, computed tomography, and digital subtraction angiography in patients with symptoms of recent or remote stroke or transient ischemic attack. Stenosis on angiography was measured as 0%, < 50%, or > or = 50% diameter reduction. RESULTS: Of 136 consecutive patients, 33 (24%) had distal internal carotid artery (ICA), middle cerebral artery (MCA), posterior cerebral artery, or basilar artery stenosis on angiography (14 patients [10%] were excluded due to incomplete TCD examinations, mainly from a lack of temporal windows). TCD showed 31 true-positive, 9 false-positive, 2 false-negative, and 94 true-negative studies. For all vessels, TCD had a sensitivity of 93.9% (confidence interval [CI] = 89%-98%), a specificity of 91.2% (CI = 87%-96%), a positive predictive value (PPV) of 77.5%, and a negative predictive value (NPV) of 97.9%. The trade-off in sensitivity and specificity for MCA MFV thresholds was as follows: MFV > or = 80 cm/s had a sensitivity of 100%, a specificity of 96.9% (CI = 94%-99%), a PPV of 84%, and an NPV of 100%. MFV > or = 100 cm/s had a sensitivity of 100%, a specificity of 97.9% (CI = 96%-99%), a PPV of 88.8%, and an NPV of 94.9%. MFV > or = 120 cm/s had a sensitivity of 68.7% (CI = 61%-78%), a specificity of 100%, a PPV of 100%, and an NPV of 94.9%. Reasons for false-positive findings include collateralization of flow in the presence of proximal ICA stenosis and prestenotic to stenotic MCA velocity ratios of 1: < or = 2. CONCLUSION: TCD is both sensitive and specific in identifying > or = 50% intracranial arterial stenosis. A MFV threshold cutoff of 100 cm/s has an optimal sensitivity and specificity trade-off for > or = 50% MCA stenosis. To help avoid false-positive results, a prestenotic to stenotic MCA velocity ratio of 1: > or = 2 should be used in addition to the MFV threshold.     

Assessment of cerebral blood flow velocities in pre and post angiographic states with transcranial doppler

The frequency of complications resulting from angiograms reported in the literature vary between 0.2-5 percent. This study was planned to determine the changes in cerebral blood flow velocity before and after angiography, using transcranial doppler in patients of subarachnoid hemorrhage (SAH) undergoing angiographies. Thirty patients with subarachnoid hemorrhage underwent transcranial doppler ultrasonography immediately before and after angiography. Nonionic water-soluble agents were used during the angiograms. The mean flow velocity (MFV) and pulsatility index (PI) at the M1 segment of both middle cerebral arteries was simultaneously measured. When the patients (11 male, 19 female, mean age+SD; 52.45+12.06) were compared according to changes in MFV and PI, pre and post-angiography, there was no statistical difference in MFV (p=0.51 and p=0.99, left and right side respectively), and in PI (p=0.48 and p=0.66) pre and post angiography. Although angiogram can be used to detect vasospasm in SAH, it can also be cause of vasospasm, partially due to the effect of the contrast agent on the cerebral arteries. This study proposes that the angiographic method is still safe and TCD can be used to follow up any possible changes in diameter of cerebral arteries before and after angiography.     

The prognostic value of pulsatility index, flow velocity, and their ratio, measured with TCD ultrasound, in patients with a recent TIA or ischemic stroke

Wijnhoud AD, Koudstaal PJ, Dippel DWJ. The prognostic value of pulsatility index, flow velocity, and their ratio, measured with TCD ultrasound, in patients with a recent TIA or ischemic stroke.
Acta Neurol Scand: 2011: 124: 238–244.
© 2011 John Wiley & Sons A/S. Background – Increased flow velocities, and combinations of low mean flow velocity (MFV) and a high pulsatility index (PI) are associated with intracranial arterial disease. We investigated the association of MFV and the ratio of PI and MFV (PI–MFV ratio) in the middle cerebral artery (MCA) with recurrence of vascular events in patients with a transient ischemic attack (TIA) or minor ischemic stroke. Methods – Five hundred and ninety‐eight consecutive patients underwent TCD investigation. Outcome events were fatal or non‐fatal stroke and the composite of stroke, myocardial infarction, or vascular death (major vascular events). Hazard ratios (HR) were estimated with Cox proportional hazards multiple regression method, adjusted for age, gender, and vascular risk factors. Results – TCD registration was successful in 489 patients. Mean follow‐up was 2.1 years. Cumulative incidence was 9% for all stroke and 12% for major vascular events. MFV over 60.5 cm/s increased the risk for both stroke (HR 2.8; 95% CI: 1.3–6.0) and major vascular events (HR 2.6; 95% CI: 1.3–5.0). Each unit increase in PI–MFV ratio was associated with a HR 2.8 (95% CI: 1.7–4.8) for stroke and HR 2.2 (95% CI: 1.3–3.6) for major vascular events. Conclusion – In patients with a TIA or non‐disabling ischemic stroke, MFV and the PI–MFV ratio in the MCA are independent prognostic factors for recurrent vascular events.     

Contrast-enhanced transcranial Doppler sonography in patients with acute cerebrovascular diseases

The aim of the study was to evaluate the diagnostic potential of galactose-based microbubble suspension (Levovist) in patients with acute cerebrovascular disease and inadequate transtemporal acoustic window, when examined by transcranial Doppler (TCD). We studied 10 patients with either transient ischemic attack (no. = 3) or stroke (no. = 7). Inadequate transtemporal acoustic window was unilateral in 3 patients and bilateral in the remaining 7 patients. Signals from middle, anterior, and posterior cerebral arteries (MCA, ACA, PCA) were recorded after injecting Levovist 300 mg/ml. Six patients needed 3 injections of Levovist, 1 patient two, and 3 patients one. Mean +/- SD duration of optimal signal enhancement was 175.2 +/- 53.2 s, range 70-290 s. Doppler waveform analysis was possible in 14 (82.3%) MCA, 11 (65%) ACA, and 9 (53%) PCA. Levovist improved the reliability of TCD in patients with acute cerebrovascular disease and insufficient transtemporal insonation.