DIAS I: duplex-sonographic assessment of the cerebrovascular status in acute stroke. A useful tool for future stroke trials

Acute Middle Cerebral Artery Occlusion Detection Using Mobile Non-Imaging Brain Perfusion Ultrasound-First Case

Mobile brain perfusion ultrasound (BPU) is a novel non-imaging technique creating only hemispheric perfusion curves following ultrasound contrast injection and has been specifically designed for early prehospital large vessel occlusion (LVO) stroke identification. We report on the first patient investigated with the SONAS^® system, a portable point-of-care ultrasound system for BPU. This patient was admitted into our stroke unit about 12 h following onset of a fluctuating motor aphasia, dysarthria and facial weakness resulting in an NIHSS of 3 to 8. Occlusion of the left middle cerebral artery occlusion was diagnosed by computed tomography angiography. BPU was performed in conjunction with injection of echo-contrast agent to generate hemispheric perfusion curves and in parallel, conventional color-coded sonography (TCCS) assessing MCAO. Both assessments confirmed the results of angiography. Emergency mechanical thrombectomy (MT) achieved complete recanalization (TICI 3) and post-interventional NIHSS of 2 the next day. Telephone follow-up after 2 years found the patient fully active in professional life. Point-of-care BPU is a non-invasive technique especially suitable for prehospital stroke diagnosis for LVO. BPU in conjunction with prehospital stroke scales may enable goal-directed stroke patient placement, i.e., directly to comprehensive stroke centers aiming for MT. Further results of the ongoing phase II study are needed to confirm this finding.

Transcranial Doppler sonography for detecting stenosis or occlusion of intracranial arteries in people with acute ischaemic stroke

BACKGROUND

An occlusion or stenosis of intracranial large arteries can be detected in the acute phase of ischaemic stroke in about 42% of patients. The approved therapies for acute ischaemic stroke are thrombolysis with intravenous recombinant tissue plasminogen activator (rt-PA), and mechanical thrombectomy; both aim to recanalise an occluded intracranial artery. The reference standard for the diagnosis of intracranial stenosis and occlusion is intra-arterial angiography (IA) and, recently, computed tomography angiography (CTA) and magnetic resonance angiography (MRA), or contrast-enhanced MRA. Transcranial Doppler (TCD) and transcranial colour Doppler (TCCD) are useful, rapid, noninvasive tools for the assessment of intracranial large arteries pathology. Due to the current lack of consensus regarding the use of TCD and TCCD in clinical practice, we systematically reviewed the literature for studies assessing the diagnostic accuracy of these techniques compared with intra-arterial IA, CTA, and MRA for the detection of intracranial stenosis and occlusion in people presenting with symptoms of ischaemic stroke.

OBJECTIVES

To assess the diagnostic accuracy of TCD and TCCD for detecting stenosis and occlusion of intracranial large arteries in people with acute ischaemic stroke.

SEARCH METHODS

We limited our searches from January 1982 onwards as the transcranial Doppler technique was only introduced into clinical practice in the 1980s. We searched MEDLINE (Ovid) (from 1982 to 2018); Embase (Ovid) (from 1982 to 2018); Database of Abstracts of Reviews of Effects (DARE); and Health Technology Assessment Database (HTA) (from 1982 to 2018). Moreover, we perused the reference lists of all retrieved articles and of previously published relevant review articles, handsearched relevant conference proceedings, searched relevant websites, and contacted experts in the field.

SELECTION CRITERIA

We included all studies comparing TCD or TCCD (index tests) with IA, CTA, MRA, or contrast-enhanced MRA (reference standards) in people with acute ischaemic stroke, where all participants underwent both the index test and the reference standard within 24 hours of symptom onset. We included prospective cohort studies and randomised studies of test comparisons. We also considered retrospective studies eligible for inclusion where the original population sample was recruited prospectively but the results were analysed retrospectively.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened the titles and abstracts identified by the search strategies, applied the inclusion criteria, extracted data, assessed methodological quality (using QUADAS-2), and investigated heterogeneity. We contacted study authors for missing data.

MAIN RESULTS

A comprehensive search of major relevant electronic databases (MEDLINE and Embase) from 1982 to 13 March 2018 yielded 13,534 articles, of which nine were deemed eligible for inclusion. The studies included a total of 493 participants. The mean age of included participants was 64.2 years (range 55.8 to 69.9 years). The proportion of men and women was similar across studies. Six studies recruited participants in Europe, one in south America, one in China, and one in Egypt. Risk of bias was high for participant selection but low for flow, timing, index and reference standard. The summary sensitivity and specificity estimates for TCD and TCCD were 95% (95% CI = 0.83 to 0.99) and 95% (95% CI = 0.90 to 0.98), respectively. Considering a prevalence of stenosis or occlusion of 42% (as reported in the literature), for every 1000 people who receive a TCD or TCCD test, stenosis or occlusion will be missed in 21 people (95% CI = 4 to 71) and 29 (95% CI = 12 to 58) will be wrongly diagnosed as harbouring an intracranial occlusion. However, there was substantial heterogeneity between studies, which was no longer evident when only occlusion of the MCA was considered, or when the analysis was limited to participants investigated within six hours. The performance of either TCD or TCCD in ruling in and ruling out a MCA occlusion was good. Limitations of this review were the small number of identified studies and the lack of data on the use of ultrasound contrast medium.

AUTHORS' CONCLUSIONS

This review provides evidence that TCD or TCCD, administered by professionals with adequate experience and skills, can provide useful diagnostic information for detecting stenosis or occlusion of intracranial vessels in people with acute ischaemic stroke, or guide the request for more invasive vascular neuroimaging, especially where CT or MR-based vascular imaging are not immediately available. More studies are needed to confirm or refute the results of this review in a larger sample of stroke patients, to verify the role of contrast medium and to evaluate the clinical advantage of the use of ultrasound.

Emergency Room Use of "Fast-Track" Ultrasound in Acute Stroke: An Observational Study

Early information on vascular status in acute stroke is essential. We analyzed whether duplex ultrasound (DUS) using a fast-track protocol provides this information without relevant delay. One hundred forty-six patients were prospectively enrolled. DUS was performed by sonographers with two levels of experience. The carotid and vertebral arteries, as well as all basal cerebral arteries, were bilaterally analyzed. Criteria for vessel analysis were (i) normal or stenosis <50%, (ii) stenosis ≥50% and (iii) occlusion. The mean duration of the ultrasound investigation was 6:07 ± 2:06 min with a significant difference between more and less experienced investigators (p < 0.0001). Insonation times decreased during the study in both groups. The sensitivity, specificity, positive predictive value and negative predictive value of ultrasound findings in comparison with computed tomography angiography were 73%, 99%, 84% and 98%, respectively. Our data suggest that "fast track" DUS is feasible and reliable. The time required for DUS assessment depends on the sonographer´s experience.

Intravenous thrombolysis in acute ischemic stroke: standard and potential future applications

Acute ischemic stroke is a medical emergency requiring urgent treatment. Randomized clinical trial and Phase IV data have provided unequivocal evidence that intravenous thrombolysis with recombinant tissue plasminogen activator (rt-PA) improves early functional outcomes by restoring brain perfusion. Moreover, these studies have shed substantial light on the factors which are associated with more favorable outcome with tPA and are related to the highest benefit-to-risk ratio. Stroke physicians should consider vascular imaging techniques to aid decision making with thrombolytic therapy. The presence of intracranial occlusion is the target of treatment with early recanalization being the goal. Successful use of intravenous thrombolysis depends on a sound understanding of the decision-making process and organization of the treating team who strives for early treatment initiation and strict adherence to the protocol. Intravenous rt-PA within 4.5 h of onset should now be a standard treatment of acute disabling ischemic stroke throughout the world. This review also summarizes intravenous thrombolysis contraindications as well as the safety of novel reperfusion therapies including tenecteplase, sonothrombolysis and the combination of alteplase with direct thrombin inhibitors or glycoprotein IIb/IIIa receptor antagonists.

The role of sonolysis and sonothrombolysis in acute ischemic stroke: a systematic review and meta-analysis of randomized controlled trials and case-control studies

OBJECTIVES

To assess the evidence on the safety and efficacy of sonothrombolysis in acute stroke.

SEARCH METHODS

Electronic databases and grey literature were searched under different MeSH terms from 1970 to present.

SELECTION CRITERIA

Randomized control trials (RCTs) and case control studies (CCSs) on sonolysis and sonothrombolysis alone or with microsphere in acute stroke patients (>18 old). Outcome measures included complete recanalization (CR) at 1-2 and 24 hours, 3 months modified Rankin Scale (mRS), and symptomatic intracerebral hemorrhage (sICH). Data was extracted to Review Manager software.

RESULTS

Fifty-seven studies were retrieved and analyzed. Ten studies (7 RCTs and 3 CCSs) were included in our meta-analysis, which revealed that sonolysis and sonothrombolysis are safe (OR of sICH: 1.14; 95% confidence interval (CI): 0.56- 2.34;P=0.71) and effective (OR of CR at 1-2 hours: 2.95;95% CI: 1.81-4.81;P<0.00001) and have more than two-fold higher likelihood of favourable long-term outcome (3-month mRS 0-2; OR: 2.20; CI:1.52-3.19;P<0.0001). Further subgroup analysis based on the presence of microsphere revealed that it is safe (OR of sICH: 1.18; CI:0.433.24;P=0.75) and effective (OR of CR: 2.61; CI: 1.36-4.99;P=0.004). Subgroup analysis based on sonolysis revealed to be safe and effective.

CONCLUSIONS

This novel treatment appears safe and effective. The evidence of microsphere as an enhancement of sonothrombolysis is evolving.

Combined systemic thrombolysis with alteplase and early hyperbaric oxygen therapy in experimental embolic stroke in rats: relationship to functional outcome and reduction of structural damage

INTRODUCTION

The only causal therapy in ischemic stroke is thrombolysis with recombinant tissue plasminogen activator (rtPA), but it is feasible only for few patients, and new therapies are needed. This study investigates the effects of systemic thrombolysis with rtPA combined with hyperbaric oxygen therapy (HBOT) in embolic stroke in rats.

METHODS

In 22 male Wistar rats, an embolic ischemic stroke was induced. The animals were randomized to one of four groups: control, thrombolysis alone, HBOT sequential or HBOT parallel with thrombolysis. HBOT (2.4 ATA, 1 h) started 45 min (sequential) or 120 min (parallel) after stroke. rtPA was given intravenously 120 min after stroke onset. Functional tests were performed after stroke induction and after treatment. After 6 h infarct volume and intracerebral hemorrhagic complications were assessed.

RESULTS

Compared to the control group only the combination of HBOT and thrombolysis significantly improved the functional outcome (p=0.03) and reduced the infarct volume (p=0.01), whereas thrombolysis alone did not show a significant benefit. In all treatment groups there was a trend towards fewer hemorrhagic transformations.

CONCLUSION

Hyperbaric oxygen in combination with thrombolysis shows neuroprotection in acute ischemic stroke in rats by reducing infarct volume and improving functional outcome in the early poststroke period.

Sonothrombolysis for the treatment of acute stroke: current concepts and future directions

Achieving rapid reperfusion transcranial color-coded duplex is the critical issue in acute stroke treatment. Ultrasound (US) generates negative pressure waves that are associated with an increase in either intrinsic or intravenous tissue plasminogen activator (tPA)-induced fibrinolytic activity. Higher rates of tPA-induced arterial recanalization, associated with a trend towards better functional outcome, have been safely achieved by using high-frequency US. By contrast, the use of low-frequency US and transcranial color-coded duplex has been linked to significant hemorrhagic complications. US-accelerated thrombolysis has been safely enhanced by lowering the amount of energy needed for acoustic cavitation with the administration of microbubbles. Other applications of US are being studied, including its intra-arterial use. Operator-independent devices, which will spread the use of these US techniques further, are also being developed. This article reviews the present status of sonothrombolysis in acute stroke treatment, highlighting both experimental and clinical studies addressing this issue, and discusses its future regarding both efficacy and safety.

Utility of transcranial Doppler ultrasound for the integrative assessment of cerebrovascular function

There is considerable utility in the use of transcranial Doppler ultrasound (TCD) to assess cerebrovascular function. The brain is unique in its high energy and oxygen demand but limited capacity for energy storage that necessitates an effective means of regional blood delivery. The relative low cost, ease-of-use, non-invasiveness, and excellent temporal resolution of TCD make it an ideal tool for the examination of cerebrovascular function in both research and clinical settings. TCD is an efficient tool to access blood velocities within the cerebral vessels, cerebral autoregulation, cerebrovascular reactivity to CO(2), and neurovascular coupling, in both physiological states and in pathological conditions such as stroke and head trauma. In this review, we provide: (1) an overview of TCD methodology with respect to other techniques; (2) a methodological synopsis of the cerebrovascular exam using TCD; (3) an overview of the physiological mechanisms involved in regulation of the cerebral blood flow; (4) the utility of TCD for assessment of cerebrovascular pathology; and (5) recommendations for the assessment of four critical and complimentary aspects of cerebrovascular function: intra-cranial blood flow velocity, cerebral autoregulation, cerebral reactivity, and neurovascular coupling. The integration of these regulatory mechanisms from an integrated systems perspective is discussed, and future research directions are explored.

[Thrombolytic therapy in cerebral infarction]

BACKGROUND

Intravenous thrombolysis has gained widespread acceptance during the last 10 years, and is the only specific treatment approved for cerebral infarction. Haukeland University hospital introduced thrombolysis in 1998. The aim of this paper is to summarize our experience with the first 100 patients who had stroke caused by middle cerebral artery (MCA) occlusion and were treated with thrombolysis.

MATERIALS AND METHODS

Patients receiving intravenous thrombolytic treatment between 1998 and 2005 were prospectively included into our database. We registered demographic data, risk factors, time aspects, short and long-term clinical results and complications.

RESULTS

Two hours after treatment, a definite clinical improvement was recorded in 30 % of patients, and after 24 hrs in 49 % of the patients. Symptomatic haemorrhages were seen in 2 % of the cases. Three patients underwent haemicraniectomy because of malignant cerebral oedema and danger of hernia. At three months follow-up, 55 % of the patients had a good outcome (independence), while 13 % were dead. Time from stroke onset to start of thrombolysis was reduced from 166 to 142 min during the study period.

INTERPRETATION

The results for the first 100 acute MCA stroke patients treated with thrombolysis in Haukeland University Hospital compare well with international data, both for clinical outcome and complications. Our results thereby support the notion that intravenous thrombolysis is effective and safe when applied as a routine treatment in a comprehensive stroke unit.

Transcranial color-coded sonography successfully visualizes all intracranial parts of the internal carotid artery using the combined transtemporal axial and coronal approach

BACKGROUND AND PURPOSE

Visualization of the intracranial internal carotid artery (ICA) with transcranial color-coded sonography (TCCS) by using the transtemporal coronal plane has been described previously. Because this approach is limited to the vertical running ICA segments, we investigated the feasibility of using TCCS to visualize all intracranial ICA segments by adding the transtemporal axial approach to the coronal plane.

MATERIALS AND METHODS

Subjects with excellent transtemporal acoustic windows were examined by TCCS by using standardized axial and coronal planes. Identification rate, flow velocities, pulsatility and resistance indices, and length (as visible in color-coded power mode) were determined.

RESULTS

A total of 120 intracranial ICAs from 60 subjects were investigated. By switching between the axial and coronal insonation planes, all intracranial segments of the ICA could be investigated in 100% of subjects-with the exception of the horizontal part of the petrosal ICA, which was identified in 96.7% of subjects.

CONCLUSIONS

TCCS becomes a reliable tool in investigating all parts of the intracranial ICA by adding the transtemporal axial approach to the coronal plane.

The Eligible study: ultrasound assessment in acute ischemic stroke within 3 hours

BACKGROUND

AIMS OF THE STUDY

to identify with echo color Doppler ultrasound of the supra-aortic vessels and transcranial color-coded duplex sonography (TCCD) various patterns of vessel occlusion within 3 h from stroke onset, to compare each group defined at the admission with clinical findings and outcome, and to study the recanalization process, independent of therapy.

METHODS

We enrolled 89 consecutive patients (mean age 68.9 years). Ultrasound evaluation was done within 3 h from stroke onset, and was repeated at 3-6 and 24-36 h, at day 5, and at 3 months. At admission, patients were divided into the following groups: internal carotid artery occlusions and stenoses (<50%, 50-69%, > or =70%, near occlusion), middle cerebral artery stenoses and occlusions, tandem occlusions and T occlusions. Vascular recanalization in each group was evaluated. Subgroups were compared for NIH Stroke Scale (NIHSS) and the outcome measures mortality, Barthel index (BI) and modified Rankin scale (mRS). Favorable outcome was defined as mRS < or =2 and BI > or =90.

RESULTS

Each subgroup differed significantly for baseline NIHSS (p < 0.0001), 3-month mortality (p = 0.0235), BI at day 5 (p = 0.0458) and mRS at 3 months (p = 0.0028), even after adjustment for treatment. T and tandem occlusions were the subgroups with the highest NIHSS scores and the poorest outcomes, and the same subgroups had the worst recanalization rates.

CONCLUSIONS

TCCD in the acute setting of stroke patients allows identification of the presence and site of clots, prediction of outcome and study of the dynamic process of vessel recanalization, in both the acute phase and follow-up.

The proteasome inhibitor VELCADE® reduces infarction in rat models of focal cerebral ischemia

The potential neuroprotective effects of VELCADE were investigated in two different models of focal cerebral ischemia. For time-window assessment, male Wistar-Kyoto rats were treated with 0.2 mg/kg VELCADE at 1, 2, or 3 h after the induction of permanent middle cerebral artery occlusion (MCAO) using the suture occlusion method (experiment 1). To evaluate effects in a different model, male Sprague-Dawley rats received 0.2 mg/kg VELCADE after embolic MCAO (experiment 2). Infarct volume was calculated based on TTC-staining 24 h postischemia and whole blood proteasome activity was fluorometrically determined in both experiments at baseline, 1 and 24 h post-MCAO. In experiment 1, a dose of 0.2 mg/kg inhibited proteasome activity by 77% and infarct volume was reduced to 175.7+/-59.9 mm3 and 205.9+/-83.9 mm3 (1 and 2 h group, respectively; p<0.05) compared to 306.5+/-48.5 mm3 (control). Treatment at 3 h was not neuroprotective (293.0+/-40.1 mm3). After embolic MCAO, infarct volume was 167.5+/-90.7 mm3 (treatment group) and 398.9+/-141.3 mm3 (control; p=0.002). In conclusion, VELCADE treatment inhibited whole blood proteasome activity and achieved significant neuroprotection in two rat models of focal cerebral ischemia at various time points poststroke.

Conservative Medical Treatment and Intravenous Thrombolysis in Acute Stroke from Carotid T Occlusion

BACKGROUND

We aimed to analyse the course of early recanalization and corresponding functional outcome in patients with an acute occlusion of the carotid T who were treated conservatively or underwent intravenous thrombolysis.

METHODS

Forty-two patients with an acute occlusion of the carotid T within 6 h were recruited from consecutive admissions to a neurological department participating in the Duplex Sonography in Acute Stroke study. All patients underwent a standardized admission and follow-up procedure. Colour-coded duplex sonography was performed on admission, 30 min after thrombolysis, and at 6 and 24 h after onset of symptoms. Recanalization of the carotid T was classified as complete, partial and absent. Functional outcome was rated with the modified Rankin scale (mRS) at 3 months as favourable (mRS 0-2) or poor (mRS 3-6).

RESULTS

Within 6 h, complete or partial recanalization occurred in 1 of 27 patients treated conservatively and in 6 of 15 thrombolysed patients. Intravenous thrombolysis predicted early recanalization also after adjustment for age, sex, cardioembolic stroke aetiology and time to treatment (adjusted odds ratio, OR, 39.7; 95% confidence interval, CI, 2.0-801.7; p = 0.016). An early recanalization was the only selected predictor of a favourable outcome (OR, 13.6; 95% CI, 1.0-179.0; p = 0.047) at regression analysis, and was achieved in 3 thrombolysed patients but in none with conservative medical treatment.

CONCLUSIONS

In patients treated conservatively, functional outcome is poor and early recanalization rarely occurs. The latter can be achieved by intravenous thrombolysis with a rate comparable to that found at an intra-arterial approach without major intracranial bleeding complications. Early recanalization is associated with a better functional outcome.

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.

Transcranial sonography in spinocerebellar ataxia type 3

BACKGROUND

Transcranial sonography (TCS) identifies hyperechogenic basal ganglia in extrapyramidal disorders such as Parkinson's disease or dystonia and reveals brain atrophy reflecting the stage of degeneration in Huntington's disease. Aim of the present study was to evaluate the diagnostic potential of TCS in spinocerebellar ataxia type 3 (SCA3), a neurodegenerative disease affecting the cerebellum, multiple pontine nuclei, substantia nigra, pallidum, putamen, caudate nucleus and long spinal tracts.

METHODS

15 patients with a molecular diagnosis of SCA3 and 15 age- and sex-matched healthy control individuals were examined with TCS. Echogenicity of the substantia nigra, caudate nucleus, pallidum, putamen, dentate nucleus and cerebellar white matter were determined quantitatively (substantia nigra by measuring the area of incresed echogenicity) or semiquantitatively (0 = none, 1 = mild, 2 = marked) on both sides and compared with the echotexture of defined brain structures. Additionally, the width of the lateral ventricles, the 3rd and 4th ventricle was measured in both groups.

RESULTS

SCA3 patients exhibited hyperechogenicities of the cerebellar white matter (57%), substantia nigra (40%), the dentate nucleus (54%), putamen (40%) and pallidum (40%) significantly more frequently (p <0.05) than controls (20%, 13%, 9%, 0%, and 0% in the corresponding areas). In none of the healthy individuals a marked signal increase could be observed, whereas 53% of SCA3 subjects had at least one region with marked echogenicity. Cerebellar atrophy as demonstrated by an enlarged 4th ventricle was observed in all SCA3 patients whereas this structure could not be differentiated from surrounding parenchyma due to its small size in healthy individuals. 3rd and lateral ventricles were significantly larger in SCA patients as compared to controls (p < 0.05).

CONCLUSIONS

TCS is a suitable and non-invasive bed-side method to detect basal ganglia hyperechogenic lesions and posterior fossa abnormalities in SCA3 patients. The pattern of echotexture alterations and brain atrophy most likely reflects distribution and morphology of the neurodegenerative process.

Atypical delayed intracranial haematoma following stereotactic biopsy of a right parietal anaplastic oligodendroglioma

The history of a 73-year-old woman with an anaplastic oligodendroglioma is presented, in whom cerebral magnetic resonance imaging (MRI) and brain single-photon emission tomography (SPECT) revealed an intracerebral lesion 17 months before, which was misinterpreted as cerebral infarction. Stereotactic biopsy confirmed the diagnosis, but 4 days after biopsy an unexpected fatal subdural and intraparenchymal bleeding occurred on the biopsy site. Neuroradiological aspects in the differential diagnosis of cerebral lesions as well as the role of small silent postbiopsy haematoma concerning further clinical deterioration are discussed.

The macrosphere model: evaluation of a new stroke model for permanent middle cerebral artery occlusion in rats

BACKGROUND AND PURPOSE

The suture middle cerebral artery occlusion (MCAO) model is widely used for the simulation of focal cerebral ischemia in rats. This technique causes hypothalamic injury resulting in hyperthermia, which can worsen outcome and obscure neuroprotective effects. Herein, we introduce a new MCAO model that avoids these disadvantages.

METHODS

Permanent MCAO was performed by intraarterial embolization using six TiO(2) macrospheres (0.3-0.4 mm in diameter) or by the suture occlusion technique. Body temperature was monitored, functional and histologic outcome was assessed after 24 h. Additional 16 rats were subjected to macrosphere or suture MCAO. Lesion progression was evaluated using magnetic resonance imaging (MRI).

RESULTS

The animals subjected to suture MCAO developed hyperthermia (>39 degrees C), while the temperature remained normal in the macrosphere MCAO group. Infarct size, functional outcome and model failure rate were not significantly different between the groups. Lesion size on MRI increased within the first 90 min and remained unchanged thereafter in both groups.

CONCLUSIONS

The macrosphere MCAO model provides reproducible focal cerebral ischemia, similar to the established suture technique, but avoids hypothalamic damage and hyperthermia. This model, therefore, may be more appropriate for the preclinical evaluation of neuroprotective therapies and can also be used for stroke studies under difficult conditions, e.g., in awake animals or inside the MRI scanner.

Prognostic and diagnostic value of global cerebral blood flow volume and cerebral transit time in acute stroke

Conventional duplex sonography is a well-established method for the assessment of the brain-supplying arteries in acute stroke. However, ultrasound (US) remains inconclusive in a significant number of stroke patients. Recently, two new US parameters, the cerebral transit time (cTT) and the global cerebral blood flow volume (CBF), have been introduced. In the present study, we investigated the diagnostic and prognostic value of both parameters in stroke patients. Conventional duplex examinations of the extra- and intracranial brain-supplying arteries and measurement of cTT and CBF were performed in 50 consecutive stroke patients within 24 h after symptom onset and compared with US findings in 22 age-matched healthy controls. Neurological deficits and the degree of disability were graded using several stroke scores, and were re-evaluated for outcome measure after 1 year. CBF and cTT were not assessable in 26% and 20% of the patients, respectively. Compared with the healthy control group, stroke patients showed a significant reduction of CBF and prolongation of cTT. More than 50% of patients with otherwise normal routine duplex examination had abnormal CBF or cTT findings. Furthermore, there was a strong correlation between the reduction of global CBF and the outcome after 1 year. Sonographic assessment of the CBF and cTT are additional parameters that might increase the diagnostic sensitivity of US in stroke patients, and may have prognostic relevance.

Impact of ultrasound contrast agents in cerebrovascular diagnostics

This review gives a summary on current ultrasound contrast agents and their composition. Methods of brain imaging using UCA, like harmonic imaging and acoustic emission, are also described. Besides contrast-enhanced conventional color duplexsonography of the extracranial brain supplying arteries, transcranial contrast investigation of the basal cerebral arteries and visualization of cerebral microcirculation are also discussed in this paper. Another main topic are the interactions between UCA, human tissue and the ultrasound system.

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 alpha=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.

Feasibility and validity of transcranial duplex sonography in patients with acute stroke

OBJECTIVES

To evaluate in a prospective multicentre setting the feasibility of transcranial colour coded duplex sonography (TCCS) for examination of the middle cerebral artery (MCA) in patients with acute hemispheric stroke, and to assess the validity of sonographic findings in a subgroup of patients who also had a correlative angiographic examination.

METHODS

TCCS was performed in 58 consecutive patients within six hours of the onset of a moderate to severe hemispheric stroke. Ultrasound contrast agent (Levovist) was applied if necessary. Thirty two patients also had computed tomography angiography (n=13), magnetic resonance angiography (n=18), or digital subtraction angiography (n=1). In 14 of these patients, both the sonographic and corresponding angiographic examination were performed within six hours of stroke onset (mean time difference between TCCS and angiography 0.8 hours). Eighteen patients, in whom angiography was carried out more than 24 hours after stroke onset, had a follow up TCCS for method comparison (mean time difference 6.1 hours).

RESULTS

Initial unenhanced TCCS performed 3.4 (SD 1.2) hours after the onset of symptoms depicted the symptomatic MCA mainstem in 32 patients (55%) (13 occlusions, one stenosis, 18 patent arteries). After signal enhancement, MCA status could be determined in 54 patients (93%) (p<0.05), showing an occlusion in 25, a stenosis in two, and a patent artery in 27 patients. In 31 of the 32 patients who had correlative angiography, TCCS and angiography produced the same diagnosis of the symptomatic MCA (10 occlusions, three stenoses, 18 patent arteries); TCCS was inconclusive in the remaining one.

CONCLUSION

TCCS is a feasible, fast, and valid non-invasive bedside method for evaluating the MCA in an acute stroke setting, particularly when contrast enhancement is applied. It may be a valuable and cost effective alternative to computed tomography and magnetic resonance angiography in future stroke trials.

Clinical application of transcranial colour-coded duplex sonography--a review

Transcranial colour-coded duplex sonography (TCCS) is a new and non-invasive ultrasound application that combines both imaging of intracranial vessels and parenchymal structures at a high spatial resolution. This manuscript reviews the clinical applications of TCCS with focus on its diagnostic abilities in acute stroke patients. Furthermore, new experimental imaging techniques are discussed.