Extracranial Duplex Sonography Research Articles

Cold stimulation of the oral cavity redistributes blood towards the brain in healthy volunteers.

The aim of this study was to analyze cold stimulation-induced changes in cerebral and cardiac hemodynamics. Upon ingestion of an ice cube, the changes in resistance index, mean flow velocity and flow index of the middle cerebral arteries (MCA) were assessed using transcranial Doppler sonography. Extracranial duplex sonography was used to measure the mean flow velocity and resistance index of the right internal carotid artery (ICA). The change in mean arterial pressure, heart rate, root mean square of successive differences (RMSSD) and end-tidal carbon dioxide pressure were analyzed additionally. These changes were compared to sham stimulation. Compared with sham stimulation, cooling of the oral cavity resulted in significant changes in cerebral and cardiac hemodynamics. The cold stimulation decreased the resistance index in the MCA (-4.5% ± 5.4%, p < 0.0001) and right ICA (-6.3% ± 15.6%, p = 0.001). This was accompanied by an increase in mean flow velocity (4.1% ± 8.0%, p < 0.0001) and flow index (10.1% ± 43.6%, p = 0.008) in the MCA. The cardiac effects caused an increase in mean arterial pressure (1.8% ± 11.2%, p = 0.017) and RMSSD (55% ± 112%, p = 0.048), while simultaneously decreasing the heart rate (-4.3% ± 9.6%, p = 0.0001). Cooling of the oral cavity resulted in substantial changes in cerebral and cardiac hemodynamics resulting in a blood flow diversion to the brain.

Prospective investigation of extracranial duplex sonography for the detection of cerebral circulatory arrest in patients with irreversible loss of brain function

Abroader distribution of bedside color-coded duplex sonography (CCD) for detection of cerebral circulatory arrest (CCA) would be important to improve its use in the diagnosis of irreversible loss of brain function (ILBF-Dx). Is extracranial compared to the commonly applied transcranial CCD of the brain-supplying vessels (ECCD vs. TCCD) equivalent for the detection of CCA in ILBF-Dx regarding specificity and sensitivity? Study period January 2019-June 2022, screening of 136 and inclusion of 114patients with severe brain lesions > 24 h after onset of fixed and dilated pupils, apnea and completed ILBF-Dx. Exclusion of patients without brainstem areflexia and guideline-conform applicability of CCD. Complementary ECCD (and TCCD, if other method used for irreversibility detection). Detection of ILBF (ILBF+) in 86.8% (99/114), no ILBF (ILBF-) in 13.2% (15/114). ECCD was fully feasible in all patients; findings matching CCA were found in 94/99 ILBF+ cases (ECCD+) and not in 5patients (ECCD-). All 15patients with ILBF- showed ECCD- findings. Thus, the specificity of ECCD was 1.0, and the sensitivity was 0.949. TCCD showed CCA in 56patients (TCCD+), and ECCD+ was also found in all of them. An inconclusive result of TCCD in ILBF+ was found in 38cases, with parallel ECCD+ in all of these patients. In 20cases, TCCD did not show CCA (TCCD-), these also showed ECCD-. Of these patients 15 were ILBF- and 5 were ILBF+. TCCD was not completely feasible or inconclusive in one third of the cases, whereas ECCD was always feasible. ECCD showed high validity with respect to the detection of CCA. Therefore, the possibility of using ECCD alone to detect CCA in ILBF-Dx should be discussed.

Relevance of Basilar Artery Study in Patients with Subclavian Steal Phenomenon

A 72-year-old male presented to the emergency department with gait instability and unclear speech. Computed tomography of the brain showed old lacunar infarcts in basal ganglia. Transcranial Doppler (TCD) sonography was normal. Extracranial Duplex sonography showed indirect hemodynamic signs of bilateral subclavian artery stenosis and both vertebral arteries also showed delayed systolic flow increase. A bilateral subclavian steal phenomenon was suspected, and arm compression tests was performed. The tests promoted reverse flow in the right VA, loss of diastolic flow in the left VA and interestingly, the normal anterograde BA flow became retrograde. Although subclavian steal is likely to be an innocuous phenomenon for the majority of our patients, it is probable that the presence of a hemodynamic effect on the basilar artery may identify those who are at special risk of neurologic symptoms. So, we recommend TCD study in all patients suffering SSP to rule out the possibility of a BA steal phenomenon.

Carotid Intima-Media Thickness in HIV-Infected Individuals: Relationship of Premature Atherosclerosis to Neuropsychological Deficits?

Background: Intima-media thickness (IMT) measured by extracranial duplex sonography is a surrogate marker for atherosclerosis. It is well known that IMT is greater in HIV patients than in age-matched healthy controls due to HIV- induced endothelial damage and metabolic side-effects of antiretroviral therapy. However, it remains unclear whether atherosclerosis has an additional impact on cognitive function in HIV patients. Therefore, the objective of this study was to investigate the correlation between IMT and neuropsychological deficits in HIV patients. Methods: 47 HIV patients and 40 age-matched healthy controls were examined by extracranial ultrasound 2 and 3 cm before the flow divider to evaluate differences in IMT. Possible neuropsychological deficits in HIV patients were assessed using a battery of 10 neuropsychological tests. Results of neuropsychological tests and markers of disease severity were correlated with IMT in HIV patients. Results: IMT was significantly greater in patients than in healthy controls (p < 0.001). However, none of the neuropsychological tests correlated significantly with IMT measurements in HIV patients. There was only a weak correlation between deficits in attention and IMT in HIV patients (r = 0.44; p = 0.005), which was non-significant after correction for multiple comparisons. Markers of disease severity (CD4 cell count, HIV load in plasma, duration of HIV disease) did not correlate with IMT either. Conclusion: IMT was greater in HIV patients compared to age-matched controls but it appears that premature atherosclerosis has no additional impact on the evolution of neuropsychological deficits in HIV patients. IMT did not correlate with the severity of immunodeficiency.

Congenital aplasia of the internal carotid artery

Introduction: Agenesis, aplasia, and hypoplasia of the internal carotid artery (ICA) are very rare congenital anomalies, occuring in less than 0.01% of the population. We report a case of congenital absence of ICA incidentally diagnosed by extracranial Duplex sonography (ECD) and confirmed by magnetic resonance imaging (MRI) and MRI-angiography.

Echo-enhanced duplex sonography of extracranial vertebral arteries

We sought to investigate the potential benefit in examining extracranial vertebral arteries (ExVA) with an echo contrast agent. A total of 26 patients with insufficiently assessable ExVA underwent extracranial duplex sonography without and with an echo contrast medium. All examinations were recorded and analysed independently by two experienced sonographers. Interrater agreement was fair in assessment of B-mode quality, colour-coding, blooming artefacts, change of v max, good to very good in all other rated categories. Using an echo contrast medium reduced overall inassessable ExVA by 48% and 36% according to the two raters, respectively. After contrast enhancement, diagnosis was clarified in ExVA formerly inassessable for hypoplasia in 60% vs. 56%, extracranial occlusion in 67% vs. 56% and resistance signal in 63% vs. 45%, respectively. Application of an echo contrast agent leads to clarification of ExVA sonographic diagnosis in approximately one third of poorly examinable patients (35% and 30%, respectively), and contributes in ruling out extracranial occlusion, hypoplasia and resistance signal. (E-mail: akhaw@neuro.columbia.edu)

Peripheral Hemodialysis Shunt With Intracranial Venous Congestion

Intracranial venous congestion is often caused by local venous thrombosis or brain arteriovenous fistulas. Hemodialysis shunts are known to cause venous enlargement in the arm or chest but have not been related to intracranial vascular pathology. Case Description- A 59-year-old woman who presented with increasing headache, gait instability, and memory loss was a renal transplant recipient who still carried a left upper arm shunt. Cranial CT scan showed enlarged veins in the posterior fossa with incipient hydrocephalus. Extracranial duplex sonography revealed reversed flow in the left internal jugular vein, which normalized on cuff inflation around the shunt-carrying arm. The reversed flow, intracranial venous congestion, and neurological status improved after surgical shunt ligation. To our knowledge, this is the first case description of an intracranial venous outflow obstruction caused by a peripheral arteriovenous shunt.

Contrast‐Enhanced Transcranial and Extracranial Duplex Sonography

Transcranial sonography is an ultrasonographic application with real problems of insufficient signal to noise ratio, which make it a primary candidate for applying ultrasonographic contrast enhancing agents. Within an international randomized multicenter phase II/III study, we investigated ten patients with insufficient Doppler signal retrieval using transcranial and extracranial color-coded duplex sonography to define safety, toxicity, optimal dosing, and the potential of the new ultrasound contrast agent SonoVue(trade mark). Patients were studied with standard color duplex systems. SonoVue(trade mark) was administered by IV bolus injection at four different doses. Efficacy parameters included the assessment of global quality of Doppler investigations, color Doppler (CD), and spectral Doppler (SD) evaluated by semiquantitative analysis using a four-point scale from 0 to 3 (very poor to excellent) and the duration of clinically useful signal enhancement. In addition, CD enhancement, evaluated at best signal enhancement, was assessed using a five-point scale, from no enhancement, slight, moderate, optimal to excessive (0-4). All examinations were compared to "gold" standard imaging (magnetic resonance imaging, digital subtraction angiography) to evaluate diagnostic confidence at optimum dosage. No serious adverse events were observed. Mean signal increase over baseline in CD or SD was 2 out of 4 points. Mean time to appearance of contrast enhancement was 22.8 seconds (9-52 sec) at the optimal dosage. The mean duration of enhancement was 281 seconds(20-593 sec) at the optimal dosage, which was of 2.4 ml of SonoVuetrade mark in nine patients. CD and SD signal enhancement (n = 20, CD + SD) was considered optimal in 12 of 20, excessive in 1 of 20, and moderate or insufficient in 5 of 20 and 2 of 20 cases, respectively. There was a tendency for superior improvement in CD signal enhancement. Diagnostic confidence was improved in 8 of 10 cases without false diagnostic conclusions. SonoVuetrade mark has been demonstrated to be a powerful and safe echo signal enhancing agent, which significantly improves transcranial and extracranial ultrasound investigations and increases the confidence in diagnosis.

Source of cerebral microembolic signals in occlusion of the internal carotid artery.

There are several possible sources of cerebral embolic ischaemia distal to an occlusion of the internal carotid artery (ICA). Our aim was to identify the source of microembolic signals in the ipsilateral middle cerebral artery (MCA) by taking simultaneous bitemporal transcranial Doppler ultrasound recordings of the ipsilateral MCA and the contralateral ACA to find the route of potential microembolic material to MCA. The study group consisted of 38 patients with an occlusion of the ICA. With extracranial duplex sonography (ACUSON 128 XP; 7 MHz), performed by an experienced sonographer, the echo intensity and echo structure of the occluded ICA in the extracranial part (proximal) were classified as homogeneous or inhomogeneous. In addition, affected segments of the ipsilateral and contralateral carotid artery with arteriosclerotic vessel walls were compared. Microembolic signals were recorded with transcranial Doppler (TCD) monitoring. The microemboli counts in the MCA and ACA were added to the sum scores. The number of affected segments of the carotid artery on the ipsilateral (the bifurcation, the external or common carotid artery) and contralateral side of occluded ICA were equally distributed. In ipsilateral MCA 3.1, 7.1 microemboli (average mean, SD) with a range of between 0 and 34 were counted, in the contralateral ACA 0.3, 0.6 (range of between 0 and 2). Regression analysis confirmed the non-predictability of the microemboli variance on the ipsilateral side of the occlusion from the variance on the contralateral side (multiple r: 0.024). We found no significant correlation between the echo intensity or echo structure of the occluded artery and an increased rate of microemboli in the ipsilateral MCA. Our results indicate a predominantly ipsilateral source for cerebral microemboli in ICA occlusion. The rate of cerebral microembolic signals was not influenced by the echo structure and echo intensity of the occluded ICA.

Noninvasive hemodynamic classification of carotid-cavernous sinus fistulas by duplex carotid sonography.

The hemodynamic classification of the CCF has important implications for prognosis and therapy, but satisfactory criteria for such a differentiation are still lacking. We studied the application of extracranial duplex sonography in 14 cases of CCF with emphasis on the hemodynamic parameters of the RI and flow volume and made a correlation with the angiographic findings. We conclude with proposed duplex sonographic criteria for hemodynamic classification: (1) small RI with increased flow volume in the ICA: direct ICA-cavernous sinus fistulas (type A); (2) normal RI and flow volume in the ICA and ECA: dural branch of ICA-cavernous sinus fistulas (type B); (3) small RI with or without increased flow volume in the ECA: dural branch of ECA-cavernous sinus fistulas (type C) or dural branches of ICA- and ECA-cavernous sinus fistulas (type D). Application for assessment of the therapeutic effectiveness was also demonstrated.