The transcranial Doppler appearance of acute carotid artery occlusion.

Transcranial Doppler ultrasound is a noninvasive technique of cerebral blood velocity measurement that is being increasingly used to detect untoward hemodynamic changes. In this report, we describe striking transcranial Doppler ultrasound changes occurring in 2 patients after cervical carotid artery occlusion that led to cerebral infarction. These changes consist of the sudden appearance of a Doppler signal of extremely low pulsatility and moderately high velocity in the middle cerebral artery distribution. In 1 patient, this signal was the first sign of carotid occlusion. We suggest that these transcranial Doppler ultrasound changes can provide an early warning of carotid artery compromise.     

Assessment of the cerebral vasomotor reactivity in internal carotid artery occlusion using a transcranial Doppler sonography and functional MRI.

BACKGROUND AND PURPOSE: Several methods are being used to assess cerebral vasomotor reactivity (CVR), including transcranial Doppler (TCD) sonography and blood oxygenation level-dependent functional magnetic resonance imaging (fMRI). The aim was to assess the correlation of TCD and fMRI in the CVR assessment. METHODS: Study group consisted of 28 patients (24 males, 4 females; aged 30-82, mean 63.1 +/- 10.0 years), presenting with 29 occluded internal carotid arteries. The TCD examination, including breath-holding/hyperventilation test (BH/HV) and breath-holding index (BHI), and fMRI examination were used for the assessment of CVR. fMRI employed a bimanual motor task within both a block paradigm and an event-related paradigm. Cohen's kappa was applied when statistically assessing correlation of the methods. RESULTS: The following correlations were found--between BH/HV and BHI 58.6%, kappa= .205; BH/HV and fMRI 65.5%, kappa= .322; BHI and fMRI 58.6%, kappa= .151; TCD (consistent result of both BH/HV and BHI test) and fMRI 70.6%, kappa= .414. CONCLUSIONS: In the evaluation of CVR, there is only a minimal correlation between the particular TCD tests (both BH/HV and BHI), and fMRI examination. However, there is a moderate correlation between TCD and fMRI in the case of congruity of both TCD tests.     

Assessment of cerebrovascular reserve capacity in patients with carotid artery disease using transcranial Doppler sonography and acetazolamide

AIM: In our study we utilised transcranial Doppler sonography (TCD) and the test with intravenously administered acetazolamide (reversible inhibitor of carbonic anhydrase) which causes vasodilatation of the brain resistance vessels to assess cerebrovascular reserve capacity (CVRC) in patients with symptomatic and asymptomatic carotid stenosis. MATERIAL: 25 patients (22 male, 3 female; aged 46-82; mean 62 years) with carotid artery disease were examined. They were qualified for the operation because of that. METHOD: Blood flow wave spectrum in the right and left middle cerebral artery (MCA) was analysed. 2 MHz pulsed-wave transducer was placed over the appropriate temporal acoustic window. We measured mean blood flow velocity (Vmean) in both MCAs. The records were taken: a) at rest, b) 15 minutes after 1.0 g of acetazolamide was administered intravenously. Cerebrovascular reserve (CVRC) was calculated as the maximal percentage increase in the appropriate MCA after the administration of acetazolamide in comparison with its value at rest. The values of CVRC were analysed statistically. RESULTS: 15 minutes after acetazolamide was injected CVRC was 44 +/- 15% (mean +/- SD) (range 0-74) in asymptomatic hemispheres. In 30 patients (97%) CVRC was 46 +/- 12% (23-74) and in 1 patient (3%) 0% (case nr 7). In the group of symptomatic hemispheres CVRC was 12 +/- 15% (-16-36) after acetazolamide administration. In 12 patients (63%) from this group CVRC was positive: 20 +/- 11% (3-33), in 4 patients (21%) CVRC was 0% (cases nr 8, 9, 22, 23) and in other 3 patients (16%) CVRC was negative: -7 +/- 8 (-16(-)-3) (cases nr 4, 12, 19). CONCLUSION: 1. The group of patients with symptomatic hemispheres have statistically lower CVRC in comparison with the group of asymptomatic hemispheres. 2. There was no statistical difference between the mean values of CVRC in patients with bilateral, severe carotid stenosis and the ones with unilateral changes. 3. We believe that such a test performed by means of TCD and intravenously injected acetazolamide can indicate a subgroup of patients with carotid stenosis for whom carotid endarterectomy is necessary at the earliest time because of possible early neurological complications appearance which are related to the lack or serious impairment of CVRC.     

Evaluation of vasomotor reactivity by transcranial Doppler and acetazolamide test before and after extracranial-intracranial bypass in patients with internal carotid artery occlusion.

BACKGROUND AND PURPOSE: The aim of this trial was to evaluate the effectiveness of extracranial-intracranial bypass with respect to vasomotor reactivity in patients with internal carotid artery occlusions and absent vasomotor reactivity, comparing them with a control group treated conservatively. METHODS: To test vasomotor reactivity in 104 patients with unilateral occlusion of the internal carotid artery, we measured blood flow velocity in the middle cerebral artery by transcranial Doppler sonography both at rest and after injection of acetazolamide. Among the 39 patients who failed to show increased mean blood flow velocity after the acetazolamide test distal to an occluded internal carotid artery by greater than or equal to 10%, 14 subjects subsequently underwent extracranial-intracranial bypass surgery (group A) and 14 age- and sex-matched subjects in whom no such procedure was done composed the control group (group B). Follow-up examinations were performed 3-6 months postoperatively and in the control group 3-6 months after initial examination. RESULTS: Baseline values of the mean blood flow velocity at rest on the affected side were reduced in both groups compared with the contralateral healthy side (group A, 46.0 +/- 15.1 cm/sec; group B, 48.1 +/- 16.7 cm/sec) and revealed only a marginal increase after acetazolamide. The contralateral side showed a normal blood flow velocity at rest and an adequate response to acetazolamide in both groups. On the follow-up examination group A demonstrated a normalized vasodilatory capacity. Blood flow velocity increased significantly after acetazolamide from 41.9 +/- 13.1 cm/sec to 53.5 +/- 16.0 cm/sec (p less than 0.002). In group B, the compromised vasomotor reactivity remained unchanged. CONCLUSIONS: Our results demonstrate that transcranial Doppler sonography together with the acetazolamide test can identify subjects with reduced vasomotor reactivity distal to an occluded internal carotid artery, who may improve hemodynamically by an extracranial-intracranial bypass.     

颈总动脉闭塞患者的临床特点分析

目的分析颈总动脉患者临床特点,以加深对该病变的认识。方法对14例颈总动脉患者的临床资料、影像及超声进行分析。结果14例颈总动脉闭塞患者中,表现为病变对侧的肢体无力7例（50%）,病变同侧一过性黑朦发作5例（35.7％）,晕厥发作5例（35.7％）;MRI显示新发梗死7例;TCD显示眼动脉血流正常6例,眼动脉侧支开放（颈内外侧枝开放）4例,眼动脉闭塞4例。结论颈动脉闭塞除了表现为肢体无力外,还可以一过性黑朦及晕厥为主要表现。     

Preoperative risk assessment for carotid occlusion by transcranial Doppler ultrasound.

OBJECTIVES: An endovascular carotid balloon occlusion test with continuous intracranial monitoring by transcranial Doppler sonography was performed in 55 patients for prediction of tolerance of a required permanent occlusion of the carotid artery. METHODS: Blood flow velocities of the ipsilateral middle cerebral artery during occlusion were recorded and compared with clinical tolerance during an occlusion test as well as with postoperative outcome after an eventual permanent occlusion. To stress the capacity of the cerebral circulation to tolerate the occlusion acetazolamide was injected before occlusion in all patients. RESULTS: The onset of neurological symptoms during temporary occlusion was dependent on the percentage fall of mean blood flow velocity relative to baseline rather than on absolute flow velocities during the time of occlusion. Patients with a fall of mean flow velocity of less than 30% tolerated temporary and permanent occlusion, with the exception of two patients who developed an infarction due to thromboembolism after iatrogenic sacrifice of the carotid artery. Patients with a major decrease developed neurological symptoms during occlusion in 55% and, in cases of carotid ligation, a haemodynamic infarction occurred. CONCLUSION: The results show that transcranial Doppler monitoring as a part of an endovascular balloon occlusion test may be a reliable technique for preoperative risk assessment for permanent occlusion of the carotid artery.     

Long term follow-up of unilateral occlusion of the internal carotid artery including repeated tests of vasomotor reactivity by transcranial Doppler

BACKGROUND: Early study on pathological flow pattern in the ophthalmic artery (OA), connected with impaired vasomotor reactivity (VMR) and low pulsatility index (PI) in the anterior cerebral artery (ACA) on the occluded side, suggested collateral exhaustion. We undertook this study to evaluate whether the occurence of new strokes is predicted by special haemodynamic features.METHOD: A total of 27 patients (22 men and five women), aged 63+/-15 years (mean+/-SD) with longstanding occlusion of the internal carotid artery (ICA), confirmed by duplex scanning were studied. They had minimal neurological deficit and were followed-up for mean 4.3+/-1.8 (mean+/-SD) years by repeated clinical and 3-D transcranial Doppler (3-D TCD) examinations with azetazolamide test of vasomotor reactivity (VMR).RESULTS: During follow-up, seven patients had new strokes (five minor strokes and two major ones), two ipsilateral and four contralateral to the ICA occlusion and one in the posterior circulation. Four patients died, All patients experiencing a new stroke had previous symptoms and pathological flow patterns in the OA, i.e retrograde or isoelectric flow were noted in six of them. One patient with contralateral stroke experienced occlusion of the ICA located above the origin of the OA with anterograde flow; otherwise none of 11 patients with anterograde flow had a new stroke (p<0.05, Fisher exact text). During the follow-up, the initial mean velocity (MV) in the middle cerebral artery (MCA) on the occluded side in six patients with a new stroke in the anterior circulation, was 26.83+/-10.50 cm/s, which was significantly different from that of patients without a new stroke (45.80+/-12.8 cm/s) (p<0.01). MV in the ICA on the non-occluded side at the last examination was greater than that at the first examination (p<0.05) and increased after the use of acetazolamide only on this side (p<0.05), while PI decreased bilateraly (p<0.001 and 0.05). Resting MV both in the MCA on the occluded and ACA on the non-occluded side slightly decreased, while MV in the posterior cerebral artery (PCA) increased on the occluded side (p<0.083) compared with that at the start of the follow-up. VMR in the ACA decreased slightly both on the non-occluded and occluded side (Delta-6.9 and Delta-5.3 respectively), while impaired VMR相似文献   

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.     

Magnetic resonance markers of ischaemia: their correlation with vasodilatory reserve in patients with carotid artery stenosis and occlusion

OBJECTIVES: Better methods of identifying patients with asymptomatic carotid artery stenosis who are at high risk of stroke are required. It has been suggested that proton magnetic resonance spectroscopy (MRS) may allow the identification of ongoing ischaemia in this patient group by the detection of a potentially reversible reduction of N-acetyl aspartate (NAA), a presumed marker of neuronal integrity, and the presence of lactate, a marker of anaerobic metabolism. Previous studies have reported metabolite ratios rather than absolute concentrations. This study was performed to determine if NAA was reduced ipsilateral to carotid stenosis or occlusion, and if its concentration was related to carbon dioxide reactivity, a marker of cerebrovascular reserve. METHODS: Twenty one patients with unilateral carotid stenosis (>70%) or occlusion were studied. Single voxel proton MRS was performed in the ipsilateral and contralateral hemispheres, with the voxel positioned in the arterial borderzone region between the middle and anterior cerebral artery territories. Absolute quantification of metabolite concentrations was performed. Cerebrovascular reactivity to 6% carbon dioxide was determined in both middle cerebral artery territories using transcranial Doppler ultrasonography. RESULTS: Mean (SD) cerebrovascular reactivity was significantly lower in the stenosed compared with the contralateral hemisphere (13.3 (7.7) v 19.2 (8.2)%/kPa, p=0.002). There were no significant differences in the absolute concentrations of NAA, choline, or creatine between the ipsilateral and contralateral hemispheres (for example, NAA 10.1 (1.1) v 10.5 (1.1) mmol/l, p=0.1). No lactate peak was seen in any spectra. For each metabolite measured, there was no correlation between the absolute concentration and cerebrovascular reactivity for either hemisphere. CONCLUSIONS: In patients with carotid stenosis and occlusion we found no evidence that chronic hypoperfusion is associated with a reduction in NAA or the presence of lactate. Magnetic resonance spectroscopy is unlikely to help in the selection of patients with asymptomatic carotid stenosis for endarterectomy.     

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.     

Short-term prognosis of stroke due to occlusion of internal carotid artery based on transcranial Doppler ultrasonography.

BACKGROUND AND PURPOSE: The clinical course of stroke due to occlusion of the internal carotid artery is influenced by amount of collateral flow. We measured mean frequency shifts in the middle cerebral artery by transcranial Doppler ultrasonography to determine its prognostic value. METHODS: Patients with proven extracranial occlusion of the internal carotid artery and ipsilateral hemispheral stroke were enrolled in our study. We performed transcranial Doppler ultrasonography on 31 patients within 48 hours after the stroke onset and followed up 25 patients in 28 days. At the same time, neurological examination with quantification of neurological deficit was done. We correlated values of flow frequency shifts on the side of stroke with degree of neurological deficit at the onset and at 28 days as well as the degree of clinical improvement and the value of frequency shifts. RESULTS: We found a negative correlation between blood flow frequency shifts in the middle cerebral artery and degree of neurological deficit at the onset (Spearman rank correlation coefficient, -0.567; p less than 0.001). We also found a positive correlation between the change of the neurological deficit during follow-up and frequency shifts at the onset (Spearman rank coefficient, 0.548; p less than 0.05). CONCLUSIONS: Diminished blood flow velocity (mean frequency shift) in the area of stroke is a negative prognostic factor for the degree of neurological deficit at the onset and a negative prognostic factor for possible improvement. Knowledge of hemodynamic conditions in the stroke area may help to improve therapeutic decisions.     

经颅多普勒超声评估单侧颈内动脉颅外段闭塞患者颅内侧支循环的临床意义

目的 探讨经颅多普勒超声(TCD)评估单侧颈内动脉颅外段闭塞(ICAO)患者颅内侧支循环的临床价值.方法 回顾性连续纳入2018年1月至2020年12月就诊于苏州大学附属第一医院卒中中心、行颈部血管超声检查为单侧ICAO及数字减影血管造影(DSA)证实患者145例,其中症状组109例,无症状组36例.记录TCD评估颅内...     

Hemodynamic flow patterns evaluated by transcranial color-coded duplex sonography after STA-MCA bypass for internal carotid artery occlusion

Extracranial-intracranial (EC-IC) bypass surgery had been widely performed for the treatment of internal carotid artery occlusion. However, it is presently difficult to predict how the bypass flow will contribute to intracranial circulation. We examined intracranial hemodynamics by transcranial color-coded duplex sonography (TCCD) after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and retrospectively studied the relationship between the postoperative contribution of the bypass flow and the preoperative collateral circulation and cerebrovascular perfusion status in 10 patients. Hemodynamics in the MCA detected by TCCD were classified into three patterns. In pattern A, perfusion of the whole MCA area is completely dependent on the bypass flow. In pattern B, perfusion of the M2 segment is dependent on the bypass flow, but perfusion of the M1 segment is independent of the bypass flow. In pattern C, perfusion of the whole MCA area is supplied by collateral flow and the bypass does not function efficiently. Preoperative absence of collateral flow via anterior communicating artery and cerebral perfusion status type 3 (reduced regional cerebral blood flow and regional cerebral vasoreactivity) seems to predict hemodynamic usefulness of the bypass flow after surgery. TCCD is an easy and noninvasive method for evaluating intracranial cerebral circulation after EC-IC bypass surgery.     

TCD对颈内动脉中度及重度狭窄患者脑血流动力学的评估价值

目的应用经颅多普勒超声(transcranial doppler,TCD)评价颈内动脉中度及重度狭窄患者的脑血流动力学变化。方法经数字减影血管造影(digital subtraction angiography,DSA)确诊单侧颈内动脉中度及重度狭窄的患者69例,采用TCD检测其大脑中动脉血流参数,评价其侧支循环开放情况和脑血流储备能力(CRV)。结果 TCD显示侧支循环开放者患侧收缩期峰时血流速度(Vs)、搏动指数(PI)及CVR明显高于无侧支循环开放患者(P0.05),颈内动脉中度狭窄组患侧收缩期峰时血流速度(Vs)、PI值及CVR明显高于重度组(P0.05)。结论颈内动脉狭窄时侧支开放可以改善远端血流动力学指标,但改善程度有限。TCD可检测颈内动脉狭窄患者颅内血流动力学变化,评价颅内侧支循环的建立情况,为临床治疗和评估提供可靠依据。