Poststenotic Distal Caliber Reduction Predicts Very High-Grade Proximal Internal Carotid Artery Stenosis.

BACKGROUND: Angiography relates the residual lumen to the poststenotic distal lumen (NASCET criterion) and expresses the result in percent lumen reduction. This method is not applicable when there is a collapse of the distal lumen, as seen in severe stenosis. The purpose of this study was to evaluate whether the reduced poststenotic caliber could be an additional sonographic criterion for estimation of the degree of stenosis. METHODS: We measured the caliber of the distal lumen of the extracranial internal carotid artery (ICA) in 57 patients with low-grade stenosis <50% (NASCET criterion), and in 57 patients with unilateral stenosis of ≥ 50 %. All were classified following international recommendations. The criteria used included the poststenotic velocity to discriminate moderate to high-grade stenosis (50-70%) from very high-grade (≥ 80 %) stenosis. In addition, we measured the interrater reliability of the ultrasonic measurement of the lumen in the distal ICA. RESULTS: In the group of patients with 50% to 70% stenosis, the distal lumen was 4.3 ± 0.6 mm. In the group with very high-grade stenosis ≥ 80%, the distal lumen was 2.6±0.5mm (p<0.0001). A distal lumen of 3.2 mm or less predicted a very high-grade stenosis with a sensitivity of 0.92 and a specificity of 0.96 (AUC 0.986; 95% CI 0.97-1.00; p=0.0001). CONCLUSION: The distal poststenotic lumen is an additional ultrasonic criterion to discriminate a very high-grade ICA stenosis from a lesser degree of ICA stenosis. It can help avoid misinterpretation due to the high variability of intrastenotic peak systolic velocities (PSV) in very high-grade ICA stenoses.

Incidence and Outcome of Aneurysmal Subarachnoid Hemorrhage: The Swiss Study on Subarachnoid Hemorrhage (Swiss SOS).

BACKGROUND AND PURPOSE: The purpose of this study was to assess nationwide incidence and outcomes of aneurysmal subarachnoid hemorrhage (aSAH). The Swiss SOS (Swiss Study on Subarachnoid Hemorrhage) was established in 2008 and offers the unique opportunity to provide this data from the point of care on a nationwide level. METHODS: All patients with confirmed aneurysmal subarachnoid hemorrhage admitted between January 1, 2009 and December 31, 2014, within Switzerland were recorded in a prospective registry. Incidence rates were calculated based on time-matched population data. Admission parameters and outcomes at discharge and at 1 year were recorded. RESULTS: We recorded data of 1787 consecutive patients. The incidence of aneurysmal subarachnoid hemorrhage in Switzerland was 3.7 per 100 000 persons/y. The number of female patients was 1170 (65.5%). With a follow-up rate of 91.3% at 1 year, 1042 patients (58.8%) led an independent life according to the modified Rankin Scale (0-2). About 1 in 10 patients survived in a dependent state (modified Rankin Scale, 3-5; n=185; 10.4%). Case fatality was 20.1% (n=356) at discharge and 22.1% (n=391) after 1 year. CONCLUSIONS: The current incidence of aneurysmal subarachnoid hemorrhage in Switzerland is lower than expected and an indication of a global trend toward decreasing admissions for ruptured intracranial aneurysms. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03245866.

Does the insula contribute to emotion-related distortion of time? A neuropsychological approach.

The literature points to a large distributed brain network involved in the estimation of time. Among these regions, the role of the insular cortex is still poorly understood. At the confluence of emotional, interoceptive, and environmental signals, this brain structure has been proposed to underlie awareness of the passage of time and emotion related time dilation. Yet, this assumption has not been tested so far. This study aimed at exploring how a lesion of the insula affects subjective duration, either in an emotional context or in a non-emotional context. Twenty-one patients with a stroke affecting the insula, either left or right, were studied for their perception of sub and supra second durations. A verbal estimation task and a temporal bisection task were used with either pure tones or neutral and emotional sounds lasting between 300 and 1500 ms and presented monaurally. Results revealed that patients with a right insular lesion, showed less temporal sensitivity than both control participants and patients with a left insular lesion. Unexpectedly, emotional effects were similar in patients and control participants. Altogether, these results suggest a specific role of the right insula in the discrimination of durations, but not in emotion related temporal distortion. In addition, an ear × emotion interaction in control participants suggests that temporal processing of positive and negative sounds may be lateralized in the brain.

PHASES Score for the Management of Intracranial Aneurysm: A Cross-Sectional Population-Based Retrospective Study.

BACKGROUND AND PURPOSE: The aim of this study is to assess whether the PHASES score allows to (1) match decisions taken by multidisciplinary team whether to observe or intervene, (2) classify patients being diagnosed with a ruptured versus unruptured intracranial aneurysm (UIA), and (3) discriminate patients at low risk of rupture from the population of patients diagnosed with intracranial aneurysm. METHODS: Population-based prospective and consecutive data were collected between 2006 and 2014. Patients (n=841) were stratified into 4 groups: stable UIA; growing observed UIA; immediately treated UIA; and aneurysmal subarachnoid hemorrhage (aSAH). All patients initially observed were pooled in a follow-up UIA group; patients from growing observed UIA, immediately treated UIA, and aSAH were pooled in a high risk of rupture group. Results are expressed as median [quartile 1, quartile 3]. RESULTS: PHASES scores of immediately treated UIA patients were significantly higher than follow-up UIA group (5 [3, 7] versus 2 [1, 4]). Patients diagnosed with UIA and PHASES score of >3 were more likely to be treated, and the score ≤3 was predictive for observation (areas under these curves=0.74). Odds of being diagnosed with an aSAH were associated with PHASES score of >3 (UIA, 4 [2, 6]; aSAH, 5 [4, 8]; areas under these curves=0.66). Scores of stable UIA patients were significantly lower than high risk of rupture group (2 [1, 4] versus 5 [4, 7]; stable UIA outcome prediction by PHASES score of ≤3: areas under these curves=0.76). CONCLUSIONS: There is a progression of PHASES score between stable UIA, growing observed UIA, immediately treated UIA, and aSAH groups. PHASES score of ≤3 is associated with a low but not negligible likelihood of aneurysm rupture, and specificity of the classifier is low.

[Spontaneous carotid and vertebral dissections]. / Dissections carotidiennes et vertébrales spontanées.

Dissections of the cervical arteries account for approximately 15-20 % of all strokes in young patients. Clinically they present with laterocervical and/or hemicranial pain associated to a Horner syndrome in case of carotid dissection and a posterior cervical pain associated to headache in the occipital area in case of vertebral dissection. A multifactorial origin is often suggested, resulting from the combination of a weakness of the arterial wall, hereditary or not, of environmental factors such minor trauma or a previous infection and also of the presence of a certain number of vascular risk factors such as high blood pressure or migraines. The diagnosis is best established with MRI which shows specifically the intramural hematoma. Treatment includes anticoagulants or antiplatelets agents.

Les dissections des artères cervicales représentent environ 15 à 20 % des accidents ischémiques cérébraux de l'adulte jeune. Cliniquement, elles se présentent par des douleurs cervicales latérales et/ou des hémicrânies associées à un syndrome de Claude-Bernard Horner en cas de dissection carotidienne, et des douleurs cervicales postérieures, associées à des céphalées au niveau de la région occipitale, en cas de dissection vertébrale. Une origine multifactorielle est souvent évoquée, résultant de la combinaison d'une faiblesse de la paroi artérielle, héréditaire ou non, de facteurs environnementaux tels un traumatisme mineur ou une infection préalable, et aussi de la présence d'un certain nombre de facteurs de risque tels que l'hypertension artérielle ou les migraines. Le diagnostic est le mieux établi à l'aide de l'IRM qui permet d'objectiver l'hématome de paroi. Le traitement comprend des agents anticoagulants ou antiplaquettaires.

[Stroke prevention in patients with atrial fibrillation]. / Prévention de l'AVC chez les patients avec une fibrillation auriculaire.

Oral anticoagulation with vitamin K antagonists (VKA) was the cornerstone of stroke prevention in atrial fibrillation (AF). This review article presents the state of the art, with regard to the treatment options developed over the past few years, the new oral anticoagulants (NOAC). A search in PubMed for relevant published studies has been performed. Dabigatran and apixaban were superior to warfarin to reduce stroke risk or systemic embolism ; dabigatran, rivaroxaban and edoxaban were non-inferior. All NOAC are globally non-inferior to warfarin for stroke prevention in non-valvular AF and they have a superior safety profile, with a reduced intracranial bleeding risk. They are now the first choice for treatment.

Les antagonistes de la vitamine K (AVK) ont été pendant longtemps la référence comme prévention de l'accident vasculaire cérébral (AVC) chez les patients souffrant de fibrillation auriculaire (FA). Cet article de revue propose une mise à jour des options thérapeutiques développées ces dernières années, à savoir les nouveaux anticoagulants oraux (NACO). Une recherche des études pertinentes a été effectuée dans PubMed. Il apparaît ainsi que le dabigatran et l'apixaban sont supérieurs à la warfarine pour réduire les AVC et les embolies systémiques ; le dabigatran, le rivaroxaban et l'édoxaban sont non inférieurs. Tous les NACO sont donc globalement non inférieurs à la warfarine pour prévenir les AVC dans la FA non valvulaire et ils ont un profil de sécurité supérieur, avec un moindre risque d'hémorragie intracrânienne. Ils représentent maintenant le traitement de premier choix.

Unruptured intracranial aneurysm follow-up and treatment after morphological change is safe: observational study and systematic review.

BACKGROUND: The management of small unruptured incidentally discovered intracranial aneurysms (SUIAs) is still controversial. The aim of this study is to assess the safety of a management protocol of SUIAs, where selected cases with SUIAs are observed and secured only if signs of instability (growth) are documented. METHODS: A prospective consecutive cohort of 292 patients (2006-2014) and 368 SUIAs (anterior circulation aneurysms (ACs) smaller than 7 mm and posterior circulation aneurysms smaller than 4 mm without previous subarachnoid haemorrhage) was observed (mean follow-up time of 3.2 years and 1177.6 aneurysm years). Factors associated with aneurysm growth were systematically reviewed from the literature. RESULTS: The aneurysm growth probability was 2.6±0.1% per year. The rate of unexpected aneurysm rupture before treatment was 0.24% per year (95% CI 0.17% to 2.40%). The calculated rate of aneurysm rupture after growth was 6.3% per aneurysm-year (95% CI 1% to 22%). Aneurysms located in the posterior circulation and aneurysms with lobulation were more likely to grow. Females or patients suffering hypertension were more likely to have an aneurysm growing. The probability of aneurysms growth increased with the size of the dome and was proportional to the number of aneurysms diagnosed in a patient. CONCLUSIONS: It is safe to observe patients diagnosed with SUIAs using periodic imaging. Intervention to secure the aneurysm should be performed after growth is observed.

Older Women Benefit from Thrombolysis as Much as Older Men.

BACKGROUND: Although the incidence of stroke among older people increases, the use of intravenous thrombolysis has initially been restricted in the elderly. However, more people aged more than 80 years, a majority of them women, may benefit from thrombolysis. Therefore characteristics, outcome, and complications in older women (aged more than 80 years) undergoing thrombolysis are studied and compared to older men and to younger women (aged less than 80 years) to detect any gender and age differences. METHODS: Retrospective study of stroke patients treated with thrombolysis based on data collected from medical records. Outcome and complications were analyzed in 3 groups in relation to age and gender. RESULTS: From a total of 108 patients treated with thrombolysis, 94 could be included in the study (36 women ≥80 years, 23 men ≥80 years, and 35 women <80 years). Improvement over the first 24 hours and at 3 months, and mortality were comparable between older women and men. Older women had more major strokes, a higher mortality, and 3-month morbidity than younger women. There was no significant difference in intracranial hemorrhage between the groups. CONCLUSIONS: We found no significant difference between older women and men in outcome and mortality after thrombolysis. Older women suffered from more severe strokes, and had a higher mortality and worse outcome than younger women. The frequency of intracranial hemorrhage was comparable. Given the higher percentage of older women suffering from more severe strokes, our results emphasize that thrombolysis should not be withheld exclusively based on age.

"Crossed" somatoparaphrenia: an unusual new case and a review of the literature.

Somatoparaphrenia is a delusional misidentification and confabulation of body parts, usually arm or hand, opposite to a cerebral lesion, generally of the "minor" right hemisphere. There is some controversy concerning lesion site (fronto-parietal; parieto-temporal; posterior insula, additional subcortical nuclei) or necessary associated symptoms (hemiparesis/plegia, anosognosia, neglect, position sense deficit). We here present a patient who is unusual in many respects, that is: (1) he is a right-hander with somatoparaphrenia after a "dominant" left-hemisphere lesion associated with aphasia and ideo-motor apraxia, but also with right hemineglect. He thus has "crossed" somatoparaphrenia; (2) his delusional misidentification concerned the right leg and not the arm or hand; (3) he has no anosognosia; (4) his proprioception is disturbed for the leg only; and (5) the lesion site is very posterior, a left occipito-parietal haemorrhage without involvement of the frontal lobe or the posterior insula. We present this case together with the seven other cases of "crossed somatoparaphrenia" with and without aphasia we found since 1935 in the literature and discuss their relevance in relation to the above controversies.

Is hemifacial spasm accompanied by hemodynamic changes detectable by ultrasound?

BACKGROUND: Arterial tortuosity of the posterior circulation compressing the facial nerve induces the ephaptic axono-axonal cross-talk that sparks hemifacial spasm. We sought if a noninvasive method such as color duplex of these arteries might detect hemodynamical changes in this condition. METHODS: Nine patients with hemifacial spasm, successfully treated with botulinum toxin, were examined with color-coded duplex ultrasound. Mean blood flow velocities of the vertebral, basilar, posterior inferior cerebellar, and anterior inferior cerebellar arteries were measured and side-to-side comparison performed. RESULTS: In all nine patients, the mean blood flow velocity, averaging across the two arteries, was higher on the side of the hemifacial spasm (Fisher's exact p < 0.008; two-tailed). The results of the repeated measures ANOVA show that the main effect of side of flow was statistically significant, F(1,8) = 17.354, p = .0032, with higher mean blood flow velocities observed on the side of the hemifacial spasm. There was no significant association between the mean flow velocity of the vertebral artery and the side of spasm (p = 0.523). CONCLUSIONS: Hemifacial spasm also seems to relate to hemodynamic changes, which may be detectable by color duplex imaging.

In vivoadaptive focusing for clinical contrast-enhanced transcranial ultrasound imaging in human.

Objective. Imaging the human brain vasculature with high spatial and temporal resolution remains challenging in the clinic today. Transcranial ultrasound is still scarcely used for cerebrovascular imaging, due to low sensitivity and strong phase aberrations induced by the skull bone that only enable the proximal part major brain vessel imaging, even with ultrasound contrast agent injection (microbubbles).Approach. Here, we propose an adaptive aberration correction technique for skull bone aberrations based on the backscattered signals coming from intravenously injected microbubbles. Our aberration correction technique was implemented to image brain vasculature in human adults through temporal and occipital bone windows. For each subject, an effective speed of sound, as well as a phase aberration profile, were determined in several isoplanatic patches spread across the image. This information was then used in the beamforming process.Main results. This aberration correction method reduced the number of artefacts, such as ghost vessels, in the images. It improved image quality both for ultrafast Doppler imaging and ultrasound localization microscopy (ULM), especially in patients with thick bone windows. For ultrafast Doppler images, the contrast was increased by 4 dB on average, and for ULM, the number of detected microbubble tracks was increased by 38%.Significance. This technique is thus promising for better diagnosis and follow-up of brain pathologies such as aneurysms, arterial stenoses, arterial occlusions, microvascular disease and stroke and could make transcranial ultrasound imaging possible even in particularly difficult-to-image human adults.

Grading carotid stenosis using ultrasonic methods.

The controversy as to whether Doppler ultrasonic methods should play a role in clinical decision-making in the prevention of stroke is attributable to reported disagreement between angiographic and ultrasonic results and the lack of internationally accepted ultrasound criteria for describing the degree of stenosis. Foremost among the explanations for both is the broad scatter of peak systolic velocities in the stenosis, the criterion that has so far received most attention. Grading based on a set of main and additional criteria can overcome diagnostic errors. Morphological measurements (B-mode images and color flow imaging) are the main criteria for low and moderate degrees of stenosis. Increased velocities in the stenosis indicate narrowing, but the appearance of collateral flow and decreased poststenotic flow velocity prove a high degree stenosis (≥70%), additionally allowing the estimation of the hemodynamic effect in the category of high-degree stenosis. Additional criteria refer to the effect of a stenosis on prestenotic flow (common carotid artery), the extent of poststenotic flow disturbances, and derived velocity criteria (diastolic peak velocity and the carotid ratio). This multiparametric approach is intended to increase the reliability and the standard of reporting of ultrasonic results for arteriosclerotic disease of the carotid artery.

Validation of a patient-specific one-dimensional model of the systemic arterial tree.

The aim of this study is to develop and validate a patient-specific distributed model of the systemic arterial tree. This model is built using geometric and hemodynamic data measured on a specific person and validated with noninvasive measurements of flow and pressure on the same person, providing thus a patient-specific model and validation. The systemic arterial tree geometry was obtained from MR angiographic measurements. A nonlinear viscoelastic constitutive law for the arterial wall is considered. Arterial wall distensibility is based on literature data and adapted to match the wave propagation velocity of the main arteries of the specific subject, which were estimated by pressure waves traveling time. The intimal shear stress is modeled using the Witzig-Womersley theory. Blood pressure is measured using applanation tonometry and flow rate using transcranial ultrasound and phase-contrast-MRI. The model predicts pressure and flow waveforms in good qualitative and quantitative agreement with the in vivo measurements, in terms of wave shape and specific wave features. Comparison with a generic one-dimensional model shows that the patient-specific model better predicts pressure and flow at specific arterial sites. These results obtained let us conclude that a patient-specific one-dimensional model of the arterial tree is able to predict well pressure and flow waveforms in the main systemic circulation, whereas this is not always the case for a generic one-dimensional model.

Simultaneous Doppelgänger and limb amputation impression in right frontal opercular stroke.

A case is described of a patient who presented almost simultaneously the impression that his left arm was amputated and the feeling of the presence of his invisible Doppelgänger. While these body scheme disorders have both been described after (right) parietal lesions, a right frontal opercular ischaemic stroke was found in the neurological work up. Diffusion tensor imaging showed that the stroke involved the ventral bundle of the superior longitudinal fasciculus that connects the parietal to the frontal lobe. The unusual clinical presentation of this frontal lesion may have been due to a 'diaschisis'-like phenomenon via the superior longitudinal fasciculus.

Transcranial ultrafast ultrasound localization microscopy of brain vasculature in patients.

Changes in cerebral blood flow are associated with stroke, aneurysms, vascular cognitive impairment, neurodegenerative diseases and other pathologies. Brain angiograms, typically performed via computed tomography or magnetic resonance imaging, are limited to millimetre-scale resolution and are insensitive to blood-flow dynamics. Here we show that ultrafast ultrasound localization microscopy of intravenously injected microbubbles enables transcranial imaging of deep vasculature in the adult human brain at microscopic resolution and the quantification of haemodynamic parameters. Adaptive speckle tracking to correct for micrometric brain-motion artefacts and ultrasonic-wave aberrations induced during transcranial propagation allowed us to map the vascular network of tangled arteries to functionally characterize blood-flow dynamics at a resolution of up to 25 µm and to detect blood vortices in a small deep-seated aneurysm in a patient. Ultrafast ultrasound localization microscopy may facilitate the understanding of brain haemodynamics and of how vascular abnormalities in the brain are related to neurological pathologies.

Safety and efficacy of ultrasound-enhanced thrombolysis: a comprehensive review and meta-analysis of randomized and nonrandomized studies.

BACKGROUND AND PURPOSE: Ultrasound-enhanced thrombolysis is a promising new approach to facilitate reperfusion therapies for acute ischemic stroke. So far, 3 different ultrasound technologies were used to increase the thrombolytic activity of tissue plasminogen activator (tPA), including transcranial Doppler (TCD), transcranial color-coded duplex (TCCD), and low-frequency ultrasound. We performed a meta-analysis to evaluate the safety and efficacy of ultrasound-enhanced thrombolysis compared to the current standard of care (intravenous tPA). SUBJECTS AND METHODS: Through Medline, Embase, and Cochrane database search, we identified and abstracted all studies of ultrasound-enhanced thrombolysis in acute cerebral ischemia. Principal investigators were contacted if data not available through peer-reviewed publication were needed. Symptomatic intracerebral hemorrhage (sICH) and recanalization rates were compared between tPA, tPA+TCD+/-microspheres (microS), tPA+TCCD+/-microS, and tPA+low-frequency ultrasound. RESULTS: A total of 6 randomized (n=224) and 3 nonrandomized (n=192) studies were identified. The rates of symptomatic intracerebral hemorrhage in randomized studies were as follows: tPA+TCD, 3.8% (95% CI, 0%-11.2%); tPA+TCCD, 11.1% (95% CI, 0%-28.9%); tPA+low-frequency ultrasound, 35.7% (95% CI, 16.2%- 61.4%); and tPA alone, 2.9% (95% CI, 0%-8.4%). Complete recanalization rates were higher in patients receiving combination of TCD with tPA 37.2% (95% CI, 26.5%- 47.9%) compared with patients treated with tPA alone 17.2% (95% CI, 9.5%-24.9%). In 8 trials of high-frequency (TCD/TCCD) ultrasound-enhanced thrombolysis, tPA+TCD/TCCD+/-microS was associated with a higher likelihood of complete recanalization (pooled OR, 2.99; 95% CI, 1.70-5.25; P=0.0001) when compared to tPA alone. High-frequency ultrasound-enhanced thrombolysis was not associated with an increased risk of symptomatic intracerebral hemorrhage (pooled OR, 1.26; 95% CI, 0.44-3.60; P=0.67). CONCLUSIONS: The present safety and signal-of-efficacy data of high-frequency ultrasound-enhanced thrombolysis should be taken into account in the design of future randomized controlled trials.

Timing of Recanalization and Functional Recovery in Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Although onset-to-treatment time is associated with early clinical recovery in acute ischemic stroke (AIS) patients treated with intravenous tissue plasminogen activator (tPA), the effect of the timing of tPA-induced recanalization on functional outcomes remains debatable. METHODS: We conducted a multicenter, prospective observational cohort study to determine whether early (within 1-hour from tPA-bolus) complete or partial recanalization assessed during 2-hour real-time transcranial Doppler monitoring is associated with improved outcomes in patients with proximal occlusions. Outcome events included dramatic clinical recovery (DCR) within 2 and 24-hours from tPA-bolus, 3-month mortality, favorable functional outcome (FFO) and functional independence (FI) defined as modified Rankin Scale (mRS) scores of 0-1 and 0-2 respectively. RESULTS: We enrolled 480 AIS patients (mean age 66±15 years, 60% men, baseline National Institutes of Health Stroke Scale score 15). Patients with early recanalization (53%) had significantly (P<0.001) higher rates of DCR at 2-hour (54% vs. 10%) and 24-hour (63% vs. 22%), 3-month FFO (67% vs. 28%) and FI (81% vs. 39%). Three-month mortality rates (6% vs. 17%) and distribution of 3-month mRS scores were significantly lower in the early recanalization group. After adjusting for potential confounders, early recanalization was independently associated with higher odds of 3-month FFO (odds ratio [OR], 6.19; 95% confidence interval [CI], 3.88 to 9.88) and lower likelihood of 3-month mortality (OR, 0.34; 95% CI, 0.17 to 0.67). Onset to treatment time correlated to the elapsed time between tPA-bolus and recanalization (unstandardized linear regression coefficient, 0.13; 95% CI, 0.06 to 0.19). CONCLUSIONS: Earlier tPA treatment after stroke onset is associated with faster tPA-induced recanalization. Earlier onset-to-recanalization time. RESULTS: in improved functional recovery and survival in AIS patients with proximal intracranial occlusions.

SiPP (Stroke in Pregnancy and Postpartum): A prospective, observational, international, multicentre study on pathophysiological mechanisms, clinical profile, management and outcome of cerebrovascular diseases in pregnant and postpartum women.

RATIONALE: Cerebrovascular diseases associated with pregnancy and postpartum period are uncommon; however, they can have an important impact on health of both women and foetus or newborn. AIMS: To evaluate the frequency, characteristics and management of cerebrovascular events in pregnant/postpartum women, to clarify pathophysiological mechanisms underlying the occurrence of these events including biomolecular aspects, and to assess the short- and long-term cerebrovascular and global cardiovascular outcome of these patients, their predictors and infant outcome. METHODS AND DESIGN: This is an observational, prospective, multicentre, international case-control study. The study will include patients with cerebrovascular events during pregnancy and/or within six months after delivery. For each included case, two controls will be prospectively recruited: one pregnant or puerperal subject without any history of cerebrovascular event and one non-pregnant or non-puerperal subject with a recent cerebrovascular event. All controls will be matched by age, ethnicity and type of cerebrovascular event with their assigned cases. The pregnant controls will be matched also by pregnancy weeks/trimester. Follow-up will last 24 months for the mother and 12 months for the infant. SUMMARY: To better understand causes and outcomes of uncommon conditions like pregnancy/postpartum-related cerebrovascular events, the development of multisite, multidisciplinary registry-based studies, such as the Stroke in Pregnancy and Postpartum study, is needed in order to collect an adequate number of patients, draw reliable conclusions and give definite recommendations on their management.

Validation of a one-dimensional model of the systemic arterial tree.

A distributed model of the human arterial tree including all main systemic arteries coupled to a heart model is developed. The one-dimensional (1-D) form of the momentum and continuity equations is solved numerically to obtain pressures and flows throughout the systemic arterial tree. Intimal shear is modeled using the Witzig-Womersley theory. A nonlinear viscoelastic constitutive law for the arterial wall is considered. The left ventricle is modeled using the varying elastance model. Distal vessels are terminated with three-element windkessels. Coronaries are modeled assuming a systolic flow impediment proportional to ventricular varying elastance. Arterial dimensions were taken from previous 1-D models and were extended to include a detailed description of cerebral vasculature. Elastic properties were taken from the literature. To validate model predictions, noninvasive measurements of pressure and flow were performed in young volunteers. Flow in large arteries was measured with MRI, cerebral flow with ultrasound Doppler, and pressure with tonometry. The resulting 1-D model is the most complete, because it encompasses all major segments of the arterial tree, accounts for ventricular-vascular interaction, and includes an improved description of shear stress and wall viscoelasticity. Model predictions at different arterial locations compared well with measured flow and pressure waves at the same anatomical points, reflecting the agreement in the general characteristics of the "generic 1-D model" and the "average subject" of our volunteer population. The study constitutes a first validation of the complete 1-D model using human pressure and flow data and supports the applicability of the 1-D model in the human circulation.

Duration of Implantable Cardiac Monitoring and Detection of Atrial Fibrillation in Ischemic Stroke Patients: A Systematic Review and Meta-Analysis.

BACKGROUND AND PURPOSE: Current guidelines do not provide firm directions on atrial fibrillation (AF) screening after ischemic stroke (IS). We sought to investigate the association of implantable cardiac monitoring (ICM) duration with the yield of AF detection in IS patients. METHODS: We included studies reporting AF detection rates by ICM in IS patients with negative initial AF screening. We excluded studies reporting prolonged cardiac monitoring with devices other than ICM, not providing AF detection rates or monitoring duration, and reporting overlapping data for the same population. The random-effects model was used for all pooled estimates and meta-regression analyses. RESULTS: We included 28 studies (4,531 patients, mean age 65 years). In meta-regression analyses, the proportion of AF detection by ICM was independently associated with monitoring duration (coefficient=0.015; 95% confidence interval [CI], 0.005 to 0.024) and mean patient age (coefficient=0.009; 95% CI, 0.003 to 0.015). No associations were detected with other patient characteristics, including IS subtype (cryptogenic vs. embolic stroke of undetermined source) or time from IS onset to CM implantation. In subgroup analyses, significant differences (P<0.001) in the AF detection rates were found for ICM duration (<6 months: 5% [95% CI, 3% to 6%]; ≥6 and ≤12 months: 21% [95% CI, 16% to 25%]; >12 and ≤24 months: 26% [95% CI, 22% to 31%]; >24 months: 34% [95% CI, 29% to 39%]). CONCLUSION: s Extended duration of ICM monitoring and increased patient age are factors that substantially increase AF detection in IS patients with initial negative AF screening.