Perspectives in Medicine最新文献

Background/aims

Cerebrovascular ultrasonography was useful clinically for evaluating cerebral hemodynamics rapidly and in real-time for patients with acute ischemic stroke. We analyzed if the patients had early recanalization or not using transcranial color-coded sonography (TCCS) in order to evaluate the usefulness of real-time monitoring in systemic thrombolysis.

Methods

Subjects were patients who had acute ischemic stroke with intravenous tissue plasminogen activator (tPA) within 3 h from onset. We evaluated occlusion of intracranial arteries from transtemporal or suboccipital window by TC-CFI with Thrombolysis in Brain Ischemia (TIBI) flow-grading system and monitored residual flow in real-time every 15 min until 120 min after the t-PA bolus.

Results

We could monitor residual flow in 5 patients who had good echo windows (4 male, mean age; 60.8 ± 6.4 years). Two patients had proximal occlusion of the middle cerebral artery (MCA), one patient had distal occlusion of MCA, one patient had M2 occlusion and one patient had distal occlusion of unilateral vertebral artery. Four patients had early complete recanalization within 60 min after the t-PA bolus (two patients within 60 min and other two patients within 30 min), however, occlusion persisted during 120 min monitoring in one patient with proximal occlusion of MCA. NIH Stroke Scale of two patients with very early recanalization was 0 at the end of the treatment. There was no symptomatic and asymptomatic intracranial hemorrhage in 4 patients except for the patients without recanalization.

Conclusions

It is anticipated that real-time ultrasound monitoring is useful for evaluating a very early thrombolytic effect of tPA connected with early clinical recovery.

Background

Sickle cell disease (SCD) is considered the most frequent cause of stroke in childhood. According to the STOP (stroke prevention trial in sickle cell anemia study) criteria, patients with abnormal values (>200 cm/s) of time-averaged mean velocities of maximum blood flow (TAMM), detected by transcranial Doppler sonography (TCD), should undergo blood transfusion in order to reduce the risk of ischemic stroke. However, patients with normal TAMM might harbor silent strokes on magnetic resonance imaging (MRI) scan. Our aim was to verify whether SCD patients with normal velocities but with a significant side-to-side asymmetry of TAMM are more prone to develop silent strokes.

Subjects and methods

Thirty-one consecutive SCD patients, (15 females; mean age: 9.23 ± 3.66 years), categorized as “normal” according to the STOP protocol (<170 cm/s) and without a history of blood transfusions and TIA/stroke, underwent a cerebral MRI scan and complete TCD evaluation in order to detect significant asymmetries in the main intracranial arteries. Then, we subdivided this cohort into two groups according to the detection of TAMM asymmetry: “normal and symmetric” (NS), “normal and asymmetric” (NA).

Results

We found 13/31 patients (41.9%) harboring a significant TAMM asymmetry (NA group), while brain MRI detected silent ischemic lesions in 13/31 (41.9%) patients. No significant differences were found between NA and NS regarding silent strokes frequencies (Chi-square test with continuity correction, χ² = 0.598), lesion number (t-student test, p = 0.09) and lesion burden (t-student test, p = 0.227).

Conclusion

According to our study, TAMM asymmetry is not a significant predictor of silent cerebral ischemia.

Transcranial sonography (TCS) of the brain parenchyma meanwhile allows a high-resolution imaging of deep brain structures in the majority of adults. A new application of TCS is the intra- and post-operative visualization with TCS and the TCS-assisted insertion of deep brain stimulation (DBS) electrodes. In pilot studies it has been shown that the TCS-assisted insertion of DBS electrodes into the subthalamic nucleus and the globus pallidus interna is feasible and safe provided the exact knowledge on the extent of electrode TCS imaging artifacts. Even more, TCS can be recommended for the post-operative monitoring of DBS electrode position. Dislocation of a DBS electrode can be easily detected. In a recent longitudinal study we could demonstrate that TCS measures of lead coordinates agreed with MRI measures in anterior–posterior and medial–lateral axis, and that the TCS-based grading of optimal vs suboptimal lead location predicts the clinical 12 months outcome of patients with movement disorders. Currently, an international multi-center study is being planned to further prove the value of TCS in the post-operative monitoring of DBS electrode position. This trial is intended to start in 2012, and is still open for joining. The obvious advantages of TCS will promote its increasing use for the intra- and post-operative monitoring of deep brain implants.

Extracranial ultrasonography is recommended to use as a baseline non-invasive method in the initial evaluation of either asymptomatic or symptomatic patients to define the possible stenosis on carotid artery.

The latest 2011 guidelines specify the sequence of examinations with certain classification of recommendations and level of evidence.

Carotid duplex ultrasonography plays an important role both in primary and secondary prevention of stroke and the results found determine the use of further investigations and management of patients with extracranial carotid and vertebral artery disease. In case of diagnostic uncertainty other brain imaging methods, like computed tomography angiography, magnetic resonance angiography and catheter-based angiography can be chosen to assess vascular lesions.

Carotid duplex ultrasound serves not only diagnostic purposes but can also be useful in the follow up processes. It is widely used for control examinations after revascularization procedures of the carotid or vertebrobasilar arteries.

By the establishment of indications of revascularization procedures degree of carotid stenosis is a major factor which therefore requires accuracy of the assessment. Carotid duplex ultrasound has some difficulties in this question. This diagnostic uncertainty is tried to be solved by improving the criteria system of stenosis grading in internal carotid artery.

The aim of this article is to give an overview about the importance and role of extracranial duplex ultrasonography in stroke prevention based on the latest guidelines.

Background

A high correlation between transcranial Doppler pulsatility index (PI) increase and intracranial hypertension has been recently demonstrated in most neurosurgical patients. But in patients with hydrocephalus PI is sometimes controversial. This may be due to a different degree of cerebral autoregulation (CA) under condition of cerebral perfusion pressure decrease.

Purpose

To compare the results of PI and CA assessment in patients with hydrocephalus.

Material and methods

Twenty-six patients (aged 16–52; male – 9, female – 17) with various types of hydrocephalus were studied. We monitored blood flow velocity in middle cerebral arteries with Multi Dop X and systemic blood pressure with Finapres-2300. CA was assessed with cuff test (evaluation of ARI) and cross-spectral analysis of spontaneous oscillations of cerebral and systemic hemodynamics within the range of Mayer's waves (evaluation of phase shift in radians – PS).

Results

Depending on presence of intracranial hypertension (ICH), all patients have been divided in two groups. Mean values of PI did not differ significantly in both groups. At the same time ARI and PS were considerably (p < 0.01) higher in patients without signs of ICH. In group of patients with ICH postoperative clinical improvement was accompanied with considerable (p < 0.05) increase of PS. In group of patients without ICH we did not observe any positive changes in neurological state postoperatively.

Conclusion

Preoperative CA assessment being more informative than PI evaluation can increase transcranial Doppler valuability in noninvasive diagnostics of cerebral spinal fluid dynamics and may be helpful in clarifying indications for operation in patients with hydrocephalus.

Background

Global cerebral blood flow (CBF), as a measure of cerebral perfusion, can be non-invasively studied using Doppler sonography. Chronic heart failure (CHF) increases the risk of stroke and dementia. One of the possible causes may be cerebral hypoperfusion in CHF patients. Therefore, we aimed to investigate the relationship between CBF and CHF severity.

Methods

The study was performed in 76 ischemic or idiopathic dilatative cardiomyopathy patients, left ventricular ejection fraction (LVEF) < 40%, with no clinical evidence of decompensation and 20 healthy volunteers. Each CHF patient was categorized according to the New NYHA criteria. All patients underwent Doppler echocardiography examination (GE Vivid 7). The LVEF was quantified using the Simpson method. CBF was estimated by a 7.0-MHz linear transducer of a computed sonography system (Toshiba Power vision 6000). CBF volume was determined as the sum of the flow volumes of the ICA and the VA of both sides.

Results

Atrial fibrillation was noted in 30%, left bundle branch block in 26%, while pacemaker was implanted in 9% of patients with CHF. History of myocardial infarction was presented in 64% of patients. No differences in age, waist/hip ratio, body mass index and lipid profile were found between CHF patients and healthy subjects. CBF was calculated in 71 of 76 patients. Three patients had occlusion of ICA, while VA was occluded in another two patients. Others did not have a hemodynamically significant ICA and VA stenosis. CBF volume was decreased in CHF patients, (677 ± 170) according to control (783 ± 128).

Conclusion

Our results of noninvasive sonographic measurement of CBF according to LVEF and NYHA criteria, suggest on significantly reduced CBF in CHF patients.

Introduction

Stenosis of intracranial arteries are responsible for 30–50% of strokes in Orientals, 11% in Hispanics, 6% in Blacks and only 1% in Caucasians. However, the clinical importance of intracranial stenosis in Whites may have been underestimated.

Subjects and methods

We examined our database registry of all TIA/ischemic stroke Caucasian patients over a two-year period, from January 1st 2009 to December 31st 2010. All patients underwent a complete cervical and intracranial ultrasound assessment, MRA and/or CTA and/or DSA.

Results

Among 292 patients (males 79.7%; mean age, 71.0 ± 12.8 years), we found 59 (20.2%) subjects harboring at least one intracranial stenosis and 20 (33.9%) patients with 2 stenosis; the total number of intracranial stenosis was 95. Regarding risk factors, hypertension was present in 67.8% of patients, diabetes in 27.1%, smoking in 30.5%, obesity in 10.2%, hypercholesterolemia in 37.3%, previous TIA/stroke in 23.7%, heart disease in 18.6%. Forty-six (77.9%) patients presented with stroke, while 13 (22.1%) with TIA. Concerning the site of stenosis, 50 (52.6%) were located in the anterior circulation [MCA 46 (48.4%), ACA 4 (4.2%)], 45 (47.4%) in the posterior circulation: [PCA 28 (29.5%), BA 11(11.6%), VA 6(6.5%)]; 46 (54.8%) on the right hemisphere, 38 (45.2%) on the left hemisphere.

Conclusions

In this university hospital-based study among Caucasian patients with acute cerebral ischemia, ultrasound disclosed a higher prevalence of intracranial stenosis than previously thought, suggesting the clinical importance of this condition in White European TIA/stroke patients.

Spontaneous cervical artery dissection is caused by a hematoma in the arterial wall. Recent research revealed that the most likely pathophysiological key mechanism is rupture of a vas vasorum resulting in a bleeding into the medio-adventitial borderzone [1]. The expansion of the hematoma into the arterial lumen can secondarily lead to a rupture of the tunica intima with a high risk of thrombus formation and embolic cerebral infarction [2]. Moreover the expansion of the hematoma causes an arterial stenosis or arterial occlusion with the risk of hemodynamic impairment. The risk of an ischemic stroke in the course of a dissection is thought to be about 70% for dissections of the internal carotid artery (ICA) [3] and about 80% for dissections of the vertebral artery (VA) [4]. The annual incidence of dissections of the ICA has been estimated to be 2.5–3/100,000 and for the VA 0.97–1.5/100,000 [5], [6]. Although dissections as such are rare they are a frequent etiology of stroke in children and young adults. Approximately 25% of the strokes in patients younger than 50 are caused by dissections with a peak age between 40 and 45 years [7], [8], [9], [10], [11], [12], [13], [14], [15], [16].

Objectives

To describe normal and pathological findings with three-dimensional (3D) ultrasound of the carotid bifurcation.

Methods

Patients admitted to our ultrasound laboratory for vascular screening were submitted to standard carotid duplex and to 3D ultrasound reconstruction of the carotid bifurcation. Volume 3D scans were performed manually, on the axial plane, and the software presented the volume rendering from the inward blood flow signal detected with the Power Color Mode.

Results

Forty normal subjects, 7 patients with caliber alterations (4 carotid bulb ectasia and 3 internal carotid lumen narrowing), 45 patients with course variations (tortuosities and kinkings) and 35 patients with internal carotid artery stenosis of various degrees have been investigated.

Conclusions

3D ultrasound is a feasible technique. It can improve carotid axis general imaging through a global image presentation “at a glance”, visualizing caliber variations and vessels course. Imaging of stenosis from inward flow can be provided, but complete stenosis characterization requires the assessment of plaque morphology and vessel wall.

Background and purpose

The early identification of ischemic stroke pathophysiology may lead to different diagnostic and therapeutical strategies. In 1/3 of patients, stroke is related to carotid disease, when a vulnerable plaque evolves with surface rupture and local apposition of highly embolic/thrombotic material. This being a rapidly evolving dynamic process, the value of its early identification may be underestimated. With the diffusion of high-resolution ultrasound equipments, the possibility of identifying these features of plaque vulnerability has become easily available. These plaque characteristics have to be always considered in the patient management, in order to avoid further worsening of neurological conditions or to prevent recurrent events, and to choose the appropriate strategies.

Methods

Early ultrasonography was performed with high frequency probes (9, 15, 18 MHz) in patients admitted to emergency area for acute ischemic symptomatology from carotid stenosis.

Results

In 8 patients admitted to the emergency area few hours after the onset of neurological symptoms, we detected peculiar plaque characteristics closely related to the neurological events and at high risk of further embolic events with local thrombosis, surface plaque rupture and carotid floating thrombi. All these cases were successfully submitted to emergency carotid endarterectomy repair.

Conclusions

Timing of carotid endarterectomy has always been debated in stroke patients’ clinical management, depending on several factors. All imaging techniques contribute to the identification of plaque morphology features, but early admission of stroke patients to the emergency areas and early US have a crucial leading role in detecting plaque rupture and dynamic changes in real-time. Peculiar characteristics of high unstable plaques allow the identification of those lesions at particularly high risk of further embolic events according to their fragile characteristics that may benefit from early surgery.