Perspectives in Medicine最新文献

Background

Ultrasound perfusion imaging (UPI) with bolus kinetic has been shown to be feasible at bedside for evaluation of perfusion deficits in stroke patients. Recent technical advances allow perfusion imaging with refill kinetics using a low mechanical index.

Methods

We examined 31 acute middle cerebral artery (MCA) stroke patients with transcranial color-coded duplex ultrasound (TCCD) and UPI. The refill of microbubbles was calculated from regions of interest in the ischemic area and the contralateral MCA territory by using the exponential function y = A(1 − e^βt); A = acoustic intensity of the plateau (dB), β = slope (1/s).

Results

We found significantly lower values of β in the ischemic area compared with the contralateral MCA territory (0.75 vs. 1.05 1/s, p < 0.05); particularly in patients with a pathological MCA flow pattern on TCCD (0.61 vs. 1.01, p < 0.01). There was a high interindividual variance without significant difference of the plateau of acoustic intensity (A) in any subgroup of patients.

Discussion

The slope parameter β of refill kinetics is useful for assessing brain perfusion in patients with acute stroke and pathological flow pattern of the ipsilateral MCA. The parameter A, however, seems more dependent from the quality of the temporal bone window.

Over the past two decades, high-resolution ultrasonography of peripheral nerves has been evolved as an adjunctive examination technique in clinical neurophysiology laboratories providing complementary information to electrodiagnostic studies. In addition to the information on nerve function, which are typically obtained by nerve conduction studies and electromyography, ultrasonography permits direct assessment of pathologic changes in nerve structure and/or in the adjacent tissue, as well. This article reviews the clinical significance of ultrasonography for the diagnostic evaluation of focal neuropathies, particularly entrapment neuropathies, traumatic nerve lesions, nerve sheath tumors, and several types of polyneuropathies. Ultrasonography offers neuromuscular clinicians a unique opportunity to conduct both complementary examination modalities by themselves without referring patients to another laboratory.

Introduction

The epidemiology and the prognosis of asymptomatic moyamoya arteriopathy is virtually unknown, mainly in white western population, while symptomatic moyamoya arteriopathy is a more known disease, both in children and in adult people. We are presenting a single centre case series of six asymptomatic adult people with a neurosonological (Transcranial Colour Coded Sonography – TCCS) suspicion of this type of cerebral arteriopathy, confirmed by Digital Subtraction Angiography (DSA).

Patients and methods

During a time period of three years we collected a series of six patients (5 female and 1 male, mean age 29.16 + 8.45 years) with a neurosonological suspicion and a neuroradiological diagnostic confirmation of moyamoya type arteriopathy. All patients underwent TCCS, brain magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) and DSA, besides the differential diagnosis of immunological or infectious etiology. The mean follow-up was 1.8 years.

Results and discussion

All patients but one had a bilateral internal carotid artery (ICA) stenosis at terminus and M1 middle cerebral artery (MCA) multiple stenoses. There is only one young patient with an atypical unilateral pathway and narrowing of extracranial ICA with prominent posterior cerebral artery (PCA) compensation. No clinical events occurred during the follow-up and also brain MRI failed to find new ischemic lesions, compared with the baseline examination.

Conclusions

Asymptomatic cerebral moyamoya arteriopathy is an infrequent but underestimated condition in young white people. More prognostic informations are needed in order to define the natural course and propose the treatment.

B-mode sonography of the optic nerve is a promising new technique in the field of neurology. It may serve as an additional diagnostic tool in different diseases with altered intracranial pressure. The aim of this article is to give an overview on this technique and on its possible clinical applications.

Vascular imaging of carotid and vertebral arteries may not be sufficient to evaluate the patients with stroke and other cerebrovascular disorders. Cerebral blood flow measurement can add information to increase the accuracy in diagnosis, assessment, and plan of management in these patients. There are many noninvasive quantitative methods to measure cerebral blood flow including volume flow rate measured by ultrasound. This article addresses mainly the different ultrasound techniques to measure cerebral blood flow. Clinical applications, volume flow rate in normal and abnormal conditions with a case example, and advantage and disadvantage of the ultrasound techniques are also described.

Introduction

Assessment of cerebral hemodynamics with transcranial Doppler (TCD) can provide real-time, bed-side assessment of important prognostic variables in acute stroke such as the status of collateral flow and vessel recanalization status. In acute middle cerebral artery (MCA) occlusion, anterior cerebral artery (ACA) flow diversion (FD) is correlated with leptomeningeal collateral flow and may be a clinically useful prognostic indicator. Continuous TCD monitoring of MCA recanalization may also provide useful prognostic information including changes in flow pattern and the occurrence of microembolic signals (MES). We present studies examining associations between ACA FD, MCA recanalization and MES patterns on the characteristics of ischemia and infarction in acute MCA stroke.

Methods

Patients studied were consecutive sub-6 h from onset internal carotid artery (ICA) territory ischemic stroke cases. A subset of these cases with MCA occlusion were studied with 2 h of continuous MCA monitoring. All patients underwent baseline multimodal computed tomographic (CT) scanning, baseline diagnostic TCD, and 24 h post stroke magnetic resonance (MR) imaging. All MCA occlusion patients studied with continuous monitoring were treated with intravenous thrombolysis. ACA flow diversion was defined as ipsilateral mean velocity of 30% or greater than the contralateral artery. Recanalization status was assessed using the Thrombolysis In Brain ischemic (TIBI) grading system and MES counted “off-line” by experienced observers. Leptomeningeal collateralisation (LMC) was graded on CT angiography. Infarct core and penumbral volumes were defined using CT perfusion thresholds. Infarct volume, reperfusion, and vessel status were measured at 24 h using MR techniques. In patients undergoing recanalization monitoring, comparison was made between those with and without major reperfusion. Multivariable regression analysis was performed to assess for any associations between ACA flow diversion, TIBI grades and MES on infarction controlling for other important clinical variables.

Results

Flow diversion: 53 patients qualified for FD analysis. ACA FD was associated with good collateral flow on CT angiography (p < 0.001) and was an independent predictor of admission infarct core volume (p < 0.001), and 24 h infarct volume (p < 0.001). The likelihood of a favourable outcome (modified Rankin score 0–2) was higher (Odds ratio = 27.5, p < 0.001) in those with flow diversion.

Recanalization monitoring: 27 patients with MCA occlusion treated with intravenous thrombolysis were included in the analysis of recanalization patterns (16 cases with major reperfusion, 11 cases of non-reperfusion). Major TIBI grade improvement (