Extracranial Doppler Research Articles

Ultrasonic diagnosis of the vertebrobasilar system. II. Transnuchal diagnosis of intracranial vertebrobasilar stenoses using a novel pulsed Doppler system

This report deals with the non-invasive detection of haemodynamically non-significant stenoses of the intracranial part of the vertebrobasilar system. A new Doppler device transmitting pulsed 2 MHz ultrasound was used. Among 67 patients with transient or stable neurological deficits of the posterior circulation area, five were found to have stenoses of the distal vertebral artery or basilar artery, respectively. Transnuchal approach via the foramen magnum was used. The findings were confirmed by angiography. Twelve subjects with normal Doppler findings also underwent angiography. Three of them presented irregularities and plaquing of the vertebrobasilar trunk without circumscribed stenosing lesions. Transcranial pulsed Doppler sonography permits non-invasive detection of intracranially located stenoses of the vertebrobasilar system which, up to now, could not be diagnosed with the help of extracranial conventional continuous-wave Doppler alone. This new method allows early detection of basilar artery occlusive disease. The effectiveness of anticoagulation and fibrinolysis can be assessed non-invasively.

European Stroke Strategies: Current Status and Problems to be Solved

Approximately 1 million Europeans suffer a stroke annually [1]. Stroke causes a greater loss of quality-adjusted life years than any other disease [2] and it poses a heavy economic burden on healthcare and social welfare. Owing to the change in the age structure of populations the number of new strokes is predicted to double in the next two decades [3]. Without more effective strategies for stroke prevention, treatment and rehabilitation such an increase of stroke is a human and economic nightmare. Furthermore, one in three of us will suffer stroke, become demented or both [4] if we are not better at stroke management and prevention in the future than we are today. Is it possible to concur such a formidable challenge? The problem is not the missing data. In a few other fields of medicine there are an equal amount of data based on randomized clinical trials. A more burning question is how to transfer the evidence-based stroke medicine into daily clinical practice. The European Stroke Initiative (EUSI), a joint effort of the European Stroke Council, the European Federation of Neurological Societies and the European Neurological Society, made a two-step survey. In the first survey, European stroke experts were asked what are the essential components for a comprehensive stroke center (CSC), primary stroke center (PSC) and any hospital ward (AHW) treating stroke patients. The experts reached a good level of agreement on what should be the main components for stroke-unit care [5]. The second step of the EUSI survey was executed among randomly selected European hospitals routinely treating stroke patients. This step aimed to find the proportion of hospitals providing appropriate care based on the consensus criteria of the CSC, PSC and AHW reached in the first survey [Unpublished Data]. The eight minimum components required for an AHW were in-house emergency department and staff, brain computerized tomography availability 24 h/7-days a week (24/7), priority for stroke patients, stroke-care maps for patient admission, prevention programs, stroke pathways and collaboration with an outside rehabilitation center. The necessary components for a PSC included, in addition to the above-mentioned AHW components, a multidisciplinary stroke team, stroke nurses, extracranial Doppler sonography, automated electrocardiography monitoring and intravenous recombinant-tissue plasminogen activator (rt-PA) protocol 24/7. For a CSC, 11 additional components in the field of vascular surgery, neurosurgery, interventional neuroradiology and clinical research were considered necessary. The second survey found a huge heterogeneity of facilities among countries: only in four countries (Finland, Luxemburg, The Netherlands and Sweden) did 25% or less of randomly selected hospitals not meet the minimum level of care, while in four countries (Estonia, France, Greece and Portugal) at least 75% of hospitals did not meet such a level.

The Main Components of Stroke Unit Care: Results of a European Expert Survey

Background and Purpose: Stroke units decrease mortality, handicap and need for institutional care, but there are only sparse evidence-based data showing which components make the difference over general wards. The aim of this survey was to identify from expert opinions what should be the major components of stroke units. Methods: A questionnaire was sent to 83 European stroke experts, to ask their opinion on what should be the components of comprehensive stroke centres (CSC), primary stroke centres (PSC) and any hospital ward (AHW) admitting acute stroke patients routinely. It consisted of a list of 107 components (personnel, diagnostic procedures, monitoring, invasive treatments provided, infrastructures, protocols and procedures and their availability for 24 h a day for 7 days a week, 24/7) to be classified as irrelevant, useful but not necessary, desirable, important but not absolutely necessary, or absolutely necessary. Results: 42 questionnaires (50.6%) were returned. Four components were excluded because of a poor level of agreement between experts. Eight components were considered as absolutely necessary by more than 75% of the experts for both CSC and PSC: multidisciplinary team, stroke-trained nurses, brain CT scan 24/7, CT priority for stroke patients, extracranial Doppler sonography, automated electrocardiographic monitoring, intravenous rt-PA protocols 24/7 and in-house emergency department. Eleven other components (in the fields of vascular surgery, neurosurgery, interventional radiology and clinical research) were considered as necessary in CSC by more than 75% of the experts. Only 8 components were considered as important but not absolutely necessary by more than 50% of the experts for AHW. Conclusion: The experts showed a high level of agreement about the essential components of organized acute stroke care, providing useful information to health authorities for the allocation of resources.

Multigate transcranial doppler ultrasound system with real-time embolic signal identification and archival

An integrated system for acquisition and processing of intracranial and extracranial Doppler signals and automatic embolic signal detection has been developed. The hardware basis of the system is a purpose-built acquisition/processing board that includes a multigate Doppler unit controlled through a computer. The signal-processing engine of the system contains a fast Fourier transform (FFT)-based, spectral-analysis unit and an embolic signal-detection unit using expert system reasoning theory. The system is designed so that up to four receive gates from a single transducer can be used to provide useful reasoning information to the embolic signal-detection unit. Alternatively, two transducers can be used simultaneously, either for bilateral transcranial Doppler (TCD) investigations or for simultaneous intra- and extracranial investigation of different arteries. The structure of the software will allow the future implementation of embolus detection algorithms that use the information from all four channels when a single transducer is used, or of independent embolus detection in two sets of two channels when two transducers are used. The user-friendly system has been tested in-vitro, and it has demonstrated a 93.6% sensitivity for micro-embolic signal (MES) identification. Preliminary in-vivo results also are encouraging.

Transcranial and extracranial ultrasound assessment of cerebral hemodynamics in vascular and Alzheimer's dementia

Background: Increasing life expectancy of the population leads to a higher incidence of dementia. Exact differentiation between the most common types, vascular dementia (VD) and Alzheimer's dementia (AD), is crucial to the development and application of new treatment strategies. Both conditions are thought to differ greatly by their extent of microvascular affection. Transcranial and extracranial ultrasound permits analysis of cerebral hemodynamics and should help to differentiate between VD and AD. We compare multimodal ultrasound data between VD, AD and controls, and give an overview of the literature on this topic.Methods: Twenty VD and 20 AD patients were studied and compared with 12 age-matched controls. Transcranial color-coded ultrasound was performed to assess blood flow velocity (Vmean) and pulsatility indices (PI) of the middle cerebral artery (MCA). Extracranial duplex and Doppler ultrasound techniques were used to assess the blood volume flow (BVF) in the anterior circulation (both internal carotid arteries [ICA]) and posterior circulation (both vertebral arteries [VA]), the global cerebral blood flow (CBF = BVFICA + BVFVA), the global cerebral circulation time (CCT = time delay of echo–contrast bolus arrival between ICA and internal jugular vein) and global cerebral blood volume (CBV = CCT × CBF).Results: MCA Vmean in VD (36 ± 8 cm/s) and AD (43 ± 13 cm/s) were significantly lower than in controls (59 ± 13 cm/s) but did not differ significantly between VD and AD groups. PI (1.1 ± 0.2; 1 ± 0.2; 0.9 ± 0.2) only differed significantly between VD group and controls. CBF and CCT in VD (570 ± 61 ml/min; 8.8 ± 2.6 s) and AD (578 ± 77 ml/min; 8.2 ± 1.4 s) were similar but differed significantly from controls (733 ± 54 ml/min; 6.4 ± 0.8 s). BVF in the anterior and posterior circulation of VD group (412 ± 62 and 158 ± 38 ml/min) and AD group (428 ± 62 and 150 ± 41 ml/min) were significantly lower than in controls (537 ± 48 and 199 ± 26 ml/min) but did not differ significantly between the patient groups.Discussion: Transcranial and extracranial ultrasound does not help to distinguish between VD and AD. However, our results add insight into the pathophysiology of dementia, arguing in favor of a common 'vascular' pathway in both conditions.

Mutations in the Gene Encoding Peroxisomal Sterol Carrier Protein X (SCPx) Cause Leukencephalopathy with Dystonia and Motor Neuropathy

In this report, we describe the first known patient with a deficiency of sterol carrier protein X (SCPx), a peroxisomal enzyme with thiolase activity, which is required for the breakdown of branched-chain fatty acids. The patient presented with torticollis and dystonic head tremor as well as slight cerebellar signs with intention tremor, nystagmus, hyposmia, and azoospermia. Magnetic resonance imaging showed leukencephalopathy and involvement of the thalamus and pons. Metabolite analyses of plasma revealed an accumulation of the branched-chain fatty acid pristanic acid, and abnormal bile alcohol glucuronides were excreted in urine. In cultured skin fibroblasts, the thiolytic activity of SCPx was deficient, and no SCPx protein could be detected by western blotting. Mutation analysis revealed a homozygous 1-nucleotide insertion, 545_546insA, leading to a frameshift and premature stop codon (I184fsX7).

Extracranial carotid Doppler ultrasound evaluation of cerebral blood flow volume in COPD patients

Doppler ultrasound of extracranial internal carotid artery (ICA) and vertebral artery (VA) were performed and total cerebral blood flow volume (tCBFV) was evaluated in chronic obstructive pulmonary disease (COPD) patients. CBFV changes due to blood gas changes were also evaluated. Bilateral ICA and VA have been examined with 7.5 MHz linear array transducer in COPD patients. Angle-corrected time averaged flow velocity and cross-sectional areas of vessels have been measured. Flow volumes and tCBFV have been calculated. Flow velocities and waveform parameters have been measured. tCBFV, anterior-posterior CBFVs, left-right ICA flow volumes, bilateral ICA and VA cross-sectional areas and left ICA peak-systolic velocity were significantly higher in COPD patients than control group. Among COPD patients tCBFVs were highest in hypoxemic-hypercapnic ones, and lowest in normocapnic ones. Bilateral VA flow volumes, bilateral ICA (except left ICA V(ps)) and VA flow velocities and waveform parameters were not different in COPD patients compared with control group. When compared among the subgroups of COPD patients, there were no significant differences for all parameters. tCBFVs were found to be significantly higher in COPD patients. This increment which is probably due to balancing the oxygen deficit is low with hypoxemia and high with hypercapnia and hypoxemia. Particularly, bilateral ICA and VA cross-sectional area changes and increased left ICA V(ps) were considered as the main reason for increased tCBFV in COPD patients.

Evaluation of total cerebral blood flow volume in cerebral atrophy

The goal of our study is to determine total cerebral blood flow volume (tCBFV) via extracranial Doppler ultrasound and to investigate its value in the differential diagnosis of dementia. Twenty-eight outpatients with cerebral atrophy confirmed by cranial computed tomography were enrolled into the study. Nine patients with Alzheimer's disease (AD) and nine patients with vascular dementia (VaD) based on neuropsychologic test and imaging findings, as well as 10 neurologically normal elderly subjects underwent Doppler sonographic examination of extracranial internal carotid artery (ICA) and vertebral artery (VA). Angle corrected time averaged flow velocity and cross-sectional areas of vessels have been measured. Flow volumes and tCBFV have been calculated. The measures of tCBFV, anterior CBFV (aCBFV), right CBFV (rCBFV) and right ICA flow volume were significantly lower in patients with dementia. The amounts of tCBFV, aCBFV, rCBFV and right ICA flow volume have been found to be low in AD and VaD patients compared with normal elderly group. Of all parameters measured for AD and VaD, no significant difference was found except Mini-Mental State Examination (MMSE) scores. To the best of our knowledge, this is the first reporting the CBF measurements using Doppler ultrasound of extracranial ICA and VA in the differential diagnosis of dementia in cerebral atrophy. The tCBFV, aCBFV, rCBFV and right ICA flow volumes and MMSE scores are significant in the diagnosis of dementia, whereas only MMSE scores are significant in the differential diagnosis of AD and VaD.

Combined Carotid and Transcranial Ultrasound Findings Compared with Clinical Classification and Stroke Severity in Acute Ischemic Stroke

Background: The aim of this study was to assess the association between cerebral hemodynamics and the clinical picture as defined by the Oxfordshire Community Stroke Project (OCSP) classification, as well as the clinical severity as defined by the National Institute of Health Stroke Scale (NIHSS) within the first 6 h of an acute middle cerebral artery (MCA) stroke onset. Methods: 70 unselected patients were grouped according to the OCSP classification and NIHSS. All patients immediately had extracranial and transcranial Doppler (TCD) ultrasound examinations. Results: In the study population as a whole, there was a significant association between intracranial vascular pathology and the OCSP classification (p < 0.001) as well as the NIHSS score (p < 0.001). In patients with severe stroke, however, TCD demonstrated the hypothesized proximal MCA₁ occlusion in only 34% of patients with an OCSP-defined total anterior circulation syndrome and in 42% of patients with an NIHSS score of ≧15. In moderate stroke, the OCSP classification was misleading in almost half of the patients with a partial anterior circulation syndrome, i.e. a hypothesized distal MCA₂ occlusion suitable for thrombolysis. Conclusions: Neither the OCSP classification nor the NIHSS grading provided reliable information about the site or presence of intracranial arterial occlusion in acute stroke within the first 6 h after stroke onset in the individual patient. The results of this study strongly suggest that selection of acute ischemic stroke patients for thrombolysis should also include an assessment of cerebral hemodynamics.

Three-Dimensional Assessment of Extracranial Doppler Sonography in Carotid Artery Stenosis Compared With Digital Subtraction Angiography

Three-Dimensional Assessment of Extracranial Doppler Sonography in Carotid Artery Stenosis Compared With Digital Subtraction Angiography

Ultrasonographic measurement of cerebral blood flow, cerebral circulation time and cerebral blood volume in vascular and Alzheimer’s dementia

Vascular dementia (VD) and Alzheimer's dementia (AD) are the most common differential diagnoses in patients with cognitive impairment. Although of different etiology, small vessel disease is postulated to be present in both conditions. We investigated global cerebral blood flow (CBF), global cerebral circulation time (CCT) and global cerebral blood volume (CBV) in VD and AD patients using a multimodal ultrasound (US) approach. 20 VD and 20 AD patients were included and compared with 12 age-matched controls. Duplex US of both internal carotid and vertebral arteries was performed to measure CBF. CCT was defined as the time delay of an echo-contrast bolus arrival between the internal carotid artery and internal jugular vein using extracranial Doppler. CBV was calculated as the product of CBF and CCT. CBF was significantly lower (VD: 570 +/- 61; AD: 578 +/- 77; controls: 733 +/- 54 ml/min) and CCT significantly longer (8.8 +/- 2.6; 8.2 +/- 1.4; 6.4 +/- 0.8 s) in both patient groups compared with controls (p < 0.003). No difference in CBF and CCT was found between the two patient groups. CBV was similar in all three groups (82 +/- 20; 79 +/- 19; 78 +/- 9 ml). The equally reduced CBF and prolonged CCT in VD and AD support the hypothesis, that small vessel disease is a relevant factor in both types of dementia. The presented multimodal US approach helps to assess the extent of changes in the global cerebral hemodynamics in patients with dementia but does not allow a differentiation between VD and AD.

Dopplersonographie mit Hinweis auf fulminante Aortendissektion bei initialem Mediainfarkt

Acute aortic dissection is a cardiovascular emergency with a wide spectrum of clinical symptoms making the diagnosis difficult if the leading symptom of thoracic pain is not present. In up to 10% of cases an ischemic stroke may be the first clinical sign. We report a patient with a middle cerebral artery infarction in whom an abnormal signal in the extracranial Doppler sonography revealed the first hint of an aortic dissection. Before the diagnosis could be verified, the patient died due to electromechanical decoupling; autopsy showed an extensive aortic dissection with cardiac tamponade. Based on this case report, we review special problems of diagnosis and therapy in aortic dissection with primary cerebrovascular manifestation.

Doppler Sonographic Evaluation of Cerebral Blood Flow in Anemia Resulting From Chronic Renal Failure

This study was undertaken to describe Doppler sonographic measurement of cerebral blood flow in anemia secondary to chronic renal failure and to compare the results with data gathered from healthy control subjects. We also aimed to compare vertebral and internal carotid artery blood flows to see whether any alteration of dominance in cerebral blood supply would occur. We studied 27 predialytic patients with chronic anemia resulting from chronic renal failure and 20 healthy control subjects by means of extracranial Doppler sonography. In these patients, blood flows of bilateral internal carotid and vertebral arteries were measured, and net vertebral artery, net internal carotid artery, and total cerebral blood flows were estimated. Statistical significance was observed between groups, and the data were correlated with hemoglobin level. Variation of the difference of the Doppler measurements between case and control groups by side (left or right) or disease status (patient or control subject) was analyzed. From the assessed Doppler parameters, only cerebral blood flow and right and net vertebral artery blood flows had a significant difference between groups (P < .05) and showed a negative correlation with hemoglobin level. Vertebral artery blood flow was found to have significant interactions with disease status (P = .009) and side (P = .054). Right vertebral artery blood flow is most prone to increase in chronic anemia of chronic renal failure. This effect also appears as increasing net vertebral artery blood flow and cerebral blood flow.

Doppler ultrasound and clinical findings in patients with acute ischemic stroke treated with intravenous thrombolysis

The aim of this study was to assess cerebral hemodynamics in patients with acute ischemic stroke undergoing thrombolytic therapy and to assess the relationship between cerebral hemodynamics and outcome. Forty-one unselected patients admitted to hospital within 3 h received intravenous thrombolytic therapy and were examined by extracranial and transcranial Doppler ultrasound examinations. Their strokes were clinically graded with the National Institute of Health Stroke Scale. Outcome after 3 months was graded with the modified Rankin Scale. Amongst the 27 patients who had an additional ultrasound examination 24 h after treatment, favorable outcome was significantly more common amongst patients with recanalization than amongst those without (P < 0.004). Thirteen patients with middle cerebral artery occlusions were continuously monitored during thrombolysis and frequently up to 5 h after start of thrombolysis. Early recanalization occurred in nine (69%), at a median delay of 178 min (range 140-287) after stroke onset. All of these nine patients had a favorable outcome. Recanalization within 24 h was associated with favorable outcome. Subgroup analysis suggests that this effect is mostly related to early recanalization within the first 5 h after stroke. Transcranial Doppler may therefore help to identify those patients most probably to benefit from thrombolysis, especially in those patients with a higher potential risk of complications.

Response:

Response:

Migrainous cerebral infarction: case reports

Migraine is a common and chronic disorder. It is considered benign but several studies have suggested it as a rare risk factor for ischaemic stroke. The association is still conflicting and seems to be restricted to particular subgroups of patients (i.e., women under the age of 45, with migraine with aura, and particularly ones who smoke and use oral contraceptives). The pathogenetic mechanisms underlying this condition are not known. We describe 6 cases of migrainous stroke fully meeting the diagnostic criteria of the International Headache Society (IHS). For each patient, demographic and anamnestic data, clinical features, results of laboratory tests and neuroimaging findings were recorded. Five of the 6 cases were women (median age of 29, range from 23 to 40). The man was 36. All patients fulfilled the IHS criteria for migraine with aura. At the time of the event, 2 patients were taking oral contraceptives and smoked, one patient smoked and three patients had no vascular risk factors. The stroke manifested as homonymous hemianopia in 3 patients, lower homonymous quadrantopia in 1 patient and sensory symptom in 1 patient. The neurological examination was normal in 1 case. All patients underwent several tests with negative results: blood test (antithrombin III, protein C or S, autoantibodies), transthoracic and transoesophageal echocardiography, extracranial and intracranial Doppler sonography, and angiography which was not performed in 1 patient. All patients had a cerebral infarct visible on neuroimaging study (MRI): posterior cerebral artery in 4, middle cerebral artery in 1 and anterior cerebral artery in 1. We support the findings reported by others that migrainous stroke is more common in young women affected by migraine with aura. In consideration of the high prevalence of migraine in the population, further research is indicated and necessary to establish if migraine is independent from other vascular risk factors.

Mechanisms of Single and Multiple Borderzone Infarct: Transcranial Doppler Ultrasound/Magnetic Resonance Imaging Correlates

Background and Purpose: Hemodynamic patterns after borderzone (BZ) infarction are variable and dynamic. However, stroke mechanisms in different types of BZ infarctions have not been systematically studied by magnetic resonance angiography (MRA) and transcranial Doppler ultrasonography (TCD). Methods: Forty-nine patients who experienced a stroke limited to the territory of either the superficial or internal borderzone proved on MRI included in our registry, corresponding to 4% of 1,200 patients with ischemic stroke, were studied. All these patients underwent MRA, extracranial Doppler ultrasonography, TCD and other investigations from the standard protocol of our registry. Twenty of them (41%) had a posterior BZ infarct, 14 (29%) an anterior BZ infarct, 10 (20%) a subcortical BZ infarct and 5 (10%) bilateral BZ infarcts. Results: Unilateral internal carotid artery (ICA) tight stenosis or occlusion ipsilateral to the lesion was present in 14 patients (70%) with a posterior BZ infarct, in 72% of those with an anterior BZ infarct, in 80% of those with a subcortical BZ infarct and in 80% of those with bilateral BZ infarcts. TCD showed cross-filling of the middle cerebral artery via the anterior communicating artery in 5 patients (25%) with a posterior BZ infarct and 10% had an increased mean flow velocity (MFV) in the ipsilateral P1 posterior cerebral artery (PCA). In patients with an anterior BZ infarct, 3 (23%) had an MFV increase in the contralateral A1 anterior cerebral artery (ACA), and 2 (15%) had a higher MFV in the ipsilateral PCA. An elevated velocity at midline depths with reversed A1 ACA flow direction was seen in 2 patients (20%) with a subcortical infarct, and 1 patient (10%) had an MFV increase in the ipsilateral P1 PCA. Left ventricular systolic dysfunction (ejection fraction <40%) was present in 50% of patients with a posterior BZ infarct, in 36% of those with an anterior BZ infarct, in 20% of those with a subcortical BZ infarct and bilateral BZ infarcts each. Conclusion: The association of severe ICA stenosis or occlusion with cardiopathies and left ventricular dysfunction may play a critical role in those with BZ infarcts having inadequate collateral supply, while a cardioembolism or acute ICA dissection may also cause BZ infarction due to the rapidity of the occlusive process and the inability of the cerebral vasculature to recruit collateral pathways quickly enough.

Surgical prophylaxis secundary to cryptogenic stroke or transient ischemic attack in patients with patent foramen ovale

INTRODUCTION: Prevention of recurrent cryptogenic strokes or transient ischemic attacks in adults with patent foramen ovale (PFO) represents a therapeutic challenge. Antithrombotic pharmacological treatment is widely used, but its indication is limited because of its significant complications. OBJECTIVE: To demonstrate the efficacy of the surgical closure of patent foramen ovale (PFO) as prophylaxis secondary to cryptogenic strokes or transient ischemic attacks of undetermined origin. METHOD: In this study, 31 men and 16 women with previous ischemic cerebral events underwent direct surgical closure of the PFO. Mean age was 40 years (from 27 to 59 years). No coexisting cause of the stroke was found after extensive investigation, including blood coagulation tests, transesophageal contrast echocardiography (TEE), extracranial and transcranial doppler ultrasonography, 24-hour electrocardiographic monitoring, brain magnetic resonance (BMR) and CT scan. Criteria for operation also included at least two of the following: atrial septal aneurysm, multiple cerebral infarcts, multiple cerebral events and a history of Valsalva strain before stroke. Before operation, only one patient had two shunts (1 PFO and 1 intrapulmonary shunt). RESULTS: No complications occurred during or after the operation, but a few hours after the operation transient arrhythmias developed in four patients without atrial fibrillation, hemodynamic instability nor embolism. All patients survived in class I (NYHA) and during a mean follow-up of 36 months, no patient had recurrence of the stroke or transient ischemic attacks. All patients prospectively underwent BMR and contrast TEE with simultaneous transcranial doppler ultrasonography. A residual right-to-left shunt, smaller than the preoperative one, was observed in only one patient, whereas no lesion was seen on the BMR. CONCLUSION: It is concluded that surgical closure of PFO in patients with presumed paradoxical embolism is safe and avoids recurrent stroke.

Ultrasonographic assessment of global cerebral blood volume in healthy adults.

The authors describe a new ultrasonographic method for analysis of global cerebral blood volume (CBV) and its application under controlled hyperventilation. CBV was determined as the product of global cerebral blood flow volume (CBF) and global cerebral circulation time. CBF was measured by duplex sonography and calculated as the sum of flow volumes in both internal carotid arteries and vertebral arteries. Extracranial Doppler assessed cerebral circulation time by determining the time interval of echo-contrast bolus arrival between internal carotid artery and contralateral internal jugular vein. Forty-four healthy volunteers (mean age 45 +/- 19 years, range 20-79 years) were studied. Mean CBV was 77 +/- 13 mL. CBV did not correlate with age, end-tidal carbon dioxide level, heart rate, or blood pressure. Hypocapnia was induced in 10 subjects by controlled hyperventilation. Mean reduction of end-tidal carbon dioxide values by 9 +/- 1 mm Hg led to a significant increase in cerebral circulation time (6.1 +/- 0.9 to 8.4 +/- 1.1 second, P < 0.0001) and a significant CBF decrease (742 +/- 85 to 526 +/- 77 mL/min, P < 0.0001), whereas CBV remained unchanged (75 +/- 6 to 73 +/- 10 mL).

Design of a multicentre study on neurosonology in acute ischaemic stroke: A Project of the Neurosonology Research Group of the World Federation of Neurology

This report summarises the design and organisation of a multicentre study on neurosonology in acute ischaemic stroke. The Neurosonology in Acute Ischaemic Stroke Study will determine whether extracranial and transcranial Doppler and duplex sonography performed within 6 h after onset of stroke improves prediction of functional outcome if applied in addition to routine diagnostic admission investigations, i.e. medical history, standardised neurological examination, brain imaging by computed or magnetic resonance tomography, electrocardiography, and baseline laboratory examination. The primary hypothesis is that there is a consistent and persuasive difference between patients with an occluded middle cerebral artery and those with an open artery in terms of the functional deficit after 3 months. Power calculations are based on the assumption of α=0.05 (two-sided test) and a probability of a maximally mild functional deficit of 0.4. Detection of a 20% difference with a power of 0.8 resulted in a calculated sample of 400 patients to be observed. Calculation took into consideration that only 50% of admitted patients would have a moderate to severe neurological deficit of whom only 30% will have an occlusion of the corresponding middle cerebral artery. Furthermore, the study is designed to evaluate a difference of the functional outcome in relation to occurrence and time of recanalisation in-patients presenting with an initially occluded middle cerebral artery.