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.

Background

Current protocols stress the importance of short-term diagnosis and treatment in recent TIA or minor stroke. The risk of a recurrent event can be predicted with embolus detection. Studies have shown that the presence of micro-emboli is associated with an increased risk of recurrent events. We explored in our patient population the effect of a zero-tolerance regime for cerebral embolism on outcome.

Methods

Patients with a recent TIA or minor stroke were assigned to a study group or control group. Both groups were treated according to European Stroke guidelines, including prompt start of anti-thrombotic therapy, statins and short-term carotid arteries duplex scanning. The study group was subjected to TCD (Delica 9 series, Shenzen Delicate Electronics Co., LTD., China) embolus detection as soon as possible (EDS, SMT Medical, Wuerzburg, Germany). If emboli were detected, treatment was started immediately to stop cerebral embolization. This was achieved by either an altered drug regimen (clopidogrel) or angioplasty or carotid endarterectomy within one or two days. If carotid intervention was indicated in the control group, it was performed within two weeks, according to European guidelines.

Results

133 patients were enrolled in the study with three months follow-up. 61 patients were subjected to the control group, 72 patients were enrolled in the study group. Recurrent events occurred in 10.2% and 3.0%, respectively (p = 0.145).

Conclusion

The current study shows a non-significant reduction in recurrent events in the study group. Probably sample size in this pilot study was insufficient to detect a significant decline. Nevertheless, the results show that embolus detection is feasible and the zero-tolerance regime may enhance the outcome of TIA and minor stroke patients. The findings support the start of a multicenter randomized trial to assess the clinical value of emboli detection in TIA and stroke care.

Background

Sickle cell disease (SCD) may impair intellectual activity; 25% of SCD patients have a significant cognitive deficit. Our aim was to verify in a cohort of children with HbSS if the presence of silent strokes or altered Time Averaged Mean velocities of Maximum blood flow (TAMM) detected by Transcranial Color Doppler (TCD) Sonography are indicators of impaired intellectual ability.

Methods

Thirty-five consecutive SCD patients (17 males; mean age: 8.6 ± 3.22) were subdivided into two groups according to neuro-psycological deficits. Cognitive function was assessed by WISC III (for the children aged 6–16 years) and WPPSI (for the children aged 4–6 years). All patients underwent a TCD scan of the main intracranial arteries, in order to detect any increase of TAMM velocities (normal <170 cm/s; altered >170 cm/s) and a cerebral MRI to reveal any silent stokes.

Results

According to the neuro-psycological evaluation, 29/35 (82.8%) patients (Group 1) had a “normal” Total Intelligence Quotient (TIQ ≥70), while 6/35 (17.2%) patients (Group 2) were defined intellectually impaired (TIQ <69).

TCD detected altered velocities in 8/35 (22.8%) patients. No significant differences were found in the percentage of altered TAMM velocities between the two groups (Fisher's exact test: p = 0.42).

MRI detected silent ischemic lesions in 14/35 patients (40.0%). No significant differences were found in silent stroke frequencies (Fisher's exact test: p = 0.25) between Group 1 and Group 2.

Conclusion

With the limitations of the study sample, according to our results, altered TAMM values and silent strokes do not seem to be indicators of impaired intellectual ability in SCD patients.

Several experimental studies have shown that noble gases can have neuroprotective effects in cerebral ischemia. The exact mechanism is unknown; increased cerebral blood flow may play a role. In order to investigate this concept we performed a n = 1 trial measuring cerebral blood flow velocity by means of transcranial Doppler (TCD) in a healthy young woman inhaling air or heliox. Peak systolic velocity, mean flow velocity and pulsatility index were measured in the right middle cerebral artery, and oxygen saturation and heart rate were measured with pulse oximetry. After a baseline of 3 min breathing normal air, heliox (79% helium, 21% oxygen) was inhaled though an oral nasal mask for 5 min, followed by a washout period of 5 min breathing normal air. This protocol was repeated four times. No significant changes were observed in hemodynamic parameters, except for a small increase in pulsatility index during heliox inhalation (from 0.91 to 0.95; p = 0.01).

In conclusion, inhalation of heliox does not influence cerebral blood flow in a healthy young person. Any beneficial effects of helium in stroke patients are more likely due to other neuroprotective effects than to hemodynamic changes.

We investigated the distribution of wall shears stress (WSS) within the carotid artery bifurcation of healthy volunteers and patients with internal carotid artery stenosis. WSS was determined by flow-sensitive 4D MRI and correlated with bifurcation angle, vessel tortuosity and the ratio of the diameter of the common (CCA) and internal carotid artery (ICA). Critical WSS occurred at the posterior wall of the physiologically dilated ICA bulb and the incidence of critical WSS values was dependent from individual bifurcation geometry. Moreover, we found that ICA stenosis changed physiological WSS distribution whereas carotid endarterectomy partially restored physiological WSS conditions.

The use of ultrasonic methods to evaluate carotid disease differs from country to country. Most popular is the criterion of flow velocity in the stenosis, a criterion influenced by multiple other factors than narrowing of the artery. On the other side angiography does not reliably measure area reduction, responsible for the hemodynamic effect of a stenosis. Therefore correlations of velocity and the degree of stenosis as measured by angiography were never satisfying. In a recent international consensus a multiparametric approach has been proposed aiming to reduce possible errors. This article illustrates some of the possible errors measuring flow velocity with Doppler ultrasound and discusses the background for using multiple criteria. Ultrasound can be used for clinical decision making. This is possible in a clear cut high degree stenosis and in low degree disease. The advantage of Doppler ultrasound is to describe best the hemodynamic consequences of vessel narrowing. This may yield important additional information in combination with other imaging modalities.

Background

Optic Neuritis (ONe) is common in Multiple Sclerosis (MS). The aim of this study was to evaluate the Optic Nerve (ONr) and its vascularisation in MS patients with and without previous ONe and in Healthy Controls (HC).

Methods

We performed high-resolution echo-color ultrasound examination in 50 subjects (29 MS patients and 21 HC). By a suprabulbar approach we measured the ONr diameter at 3 mm from the retinal plane and at another unfixed point. We assessed the flow velocities of Ophthalmic Artery (OA), Central Retinal Artery (CRA) and Central Retinal Vein (CRV) measuring the Peak Systolic Velocity (PSV) and the End Diastolic Velocity (EDV) for the arteries and the Maximal Velocity (MaxV), Minimal Velocity (MinV) and mean Velocity (mV) for the veins. The Pulsatility Index (PI) and the Resistive Index (RI) were also calculated.

Results

No significant variation for OA supply was found as well as no significant variation for CRA supply, while significant higher PI in the CRV of non-ONe MS eyes vs. both HC and ONe MS eyes was measured. We found that ONr diameter was decreased significantly from HC to non-ONe MS eyes and ONe MS eyes.

Conclusions

Ultrasound examination of ONr and its vascularisation is feasible and can demonstrate ON atrophy. The increase of CRV PI in unaffected eyes of MS patients is intriguing and seems not associated to ONr atrophy. Larger studies are needed to confirm these results.