A study in children with headaches associated mainly with venous hemodynamic disturbances has been performed. The role of cerebral venous disturbances has been defined in children with structural cerebral abnormalities: craniovertebral junction anomalies (Chiari abnormalities I) and hypoplasia of cerebral venous sinuses. Disturbances of cerebral hemodynamics revealed by ultrasonic methods determine the management of patients with different cerebral venous abnormalities.
Since the first discovery, that ultrasound can overcome the skull allowing examination of the intracranial blood-flow as well as the first description of substantia nigra (SN) signal alterations via B-mode sonography, a plethora of applications especially in the field of movement disorders have been fostered. Up to now, however, most studies investigated adult individuals, even though numerous of the diseases studied have their onset already during childhood or adolescence. This overview summarizes recent studies of transcranial B-mode sonography (TCS) within the movement disorder field and outlines potential implications for pediatric applications.
To demonstrate diagnostic abilities of space–time (4D) ultrasound imaging in patients with eye pathology and some neuro-ophthalmic syndromes.
Fifteen healthy controls and 15 patients with eye pathology (papilledema, retinal detachment, macular degeneration and intraocular metastasis) were studied by multimodal (color duplex, B-flow and 3D/4D imaging) sonography.
Normal optic disc resulted in a smooth and sharp contour without swelling. Papilledema was presented as a hyperechoic prominence into the vitreous. On its side the optic sheath diameter was increased in association with the degree of optic disc swelling. The retinal detachment was imaged as a hyperechoic undulating membrane, the neovascular macular degeneration – as a hyperechoic membrane behind the retina, and the intraocular metastasis – as irregular unifocal formation into the vitreous.
The 4D neuro-ophthalmo-sonology helps for the quick and non-invasive volume imaging of the type, size, location and severity of optic disc and optic nerve edema and its differentiation from other types of eye lesions.
Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy (CEA) is a potential life-threatening disease. Identification of patients at risk for CHS commonly takes place with use of intra-operative transcranial Doppler (TCD), but is associated with both false positive and false negative results. We aimed to determine the diagnostic value for predicting CHS, by adding a TCD measurement in the early post-operative phase after CEA.
We retrospectively included 72 patients who underwent CEA between January 2004 and August 2010 and in whom both intra- and post-operative TCD of the ipsilateral middle cerebral artery monitoring were performed. Twelve patients (17%) had an intra-operative mean blood flow velocity (Vmean) increase >100% and 13 patients (18%) a post-operative Vmean increase of >100%. In 5 patients (7%) CHS was diagnosed; 2 of those had an intra-operative Vmean increase of >100% and all 5 a post-operative Vmean increase >100%. This results in a positive predictive value of 17% for the intra-operative and 38% for the post-operative measurement.
In conclusion, a post-operative increase of the mean velocity in the ipsilateral middle cerebral artery of >100% as measured by TCD is superior to an intra-operative velocity increase, for the identification of patients at risk for the development of CHS after CEA.
Sonothrombolysis using diagnostic ultrasound (US) in combination with microbubble (MB) contrast agents is an attractive trial. Superheated perfluorocarbon nanodroplet (SPN), which can turn into MBs upon US trigger, may have advantages in sonothrombolysis. As a preliminary investigation of SPN-assisted sonothrombolysis, we performed a safety evaluation in vivo.
Twenty male rabbits (2.59 ± 0.14 kg) were assigned to three groups: the Control group (n = 6), 2.2 mL/kg of physiological saline intravascular (i.v.) injection into auricular vein; the PL group (n = 8), 25 mg/kg of phospholipid-coated SPN i.v.; and the AA group (n = 6), 25 mg/kg of SPN coated with poly aspartic acid derivative i.v. Rectal temperatures were maintained at 39.08 ± 0.98 °C. Neurological evaluation and biochemical blood examinations were performed at pre-injection, 1, 4, and 7 days after injection. Organ samples including heart, lungs, liver, spleen and kidneys were harvested after euthanasia.
Within an hour after administration of SPNs, both the PL and AA groups showed a reversible change in respiration. One animal in the AA showed transient nystagmus about 20 min after administration; however, there was no pathological damage. One animal in the PL died 2 days after. No histological damage was found in any organ sample from any of the animals. Moreover, no significant differences were found in the biochemical blood examination between the PL, AA, and Control groups.
No neurological damage or histological change was found with two SPNs. We will further investigate the SPN-assisted sonothrombolysis based on the 500-kHz US exposure with bubble liposome acceleration of rt-PA efficacy.
The aim of this preliminary study is to evaluate the hypothesis of a possible causal link between the anatomical findings of vertebral artery hypoplasia (VAH) and the incidence of posterior circulation stroke. We used full ultrasonographic examination to evaluate patients with stroke in the vertebrobasilar circulation territory over a period of 1.5 years. The diameter equal or less than 2.5 mm (in V1 and V2 segment of the vertebral artery) was set as a feature of vertebral artery hypoplasia. Magnetic resonance imaging and angiography (MRI and MRA) or computed tomography and angiography (CT and CTA) were performed to confirm the anatomic variation of hypoplasia and the site of the cerebral ischemic territory. In the group of 44 stroke patients, 9 (20%) had a hypoplastic vertebral artery and 35 (80%) were without VAH. Although vertebral artery hypoplasia in previously published literature is seldom shown as a leading risk factor for stroke in vertebrobasilar (posterior) circulation, its occurrence is not negligible and in coexistence with known risk factors of stroke may increase the negative clinical impact. Vertebral artery hypoplasia can be diagnosed non-invasively with duplex ultrasonography. It is therefore a useful method for detection of this anatomic variation and for follow-up examination.
The identification of vulnerable and unstable carotid atherosclerotic lesions is up-to-date an important topic of research, in order to adopt the adequate strategy for preventing cerebrovascular events. Plaque inflammation, presence of adventitial vasa vasorum, intimal angiogenesis and plaque neovascularization have been identified in histological studies as indicators of the instability of the atheroma of carotid arteries in cerebrovascular patients and of coronary arteries in cardiovascular patents. Consequently, the identification “in vivo” of these pathophysiological aspects has been objective for the development of new imaging techniques. Ultrasound of carotid arteries, with ultrasound contrast agents, is not only able to provide an enhanced visualization of the arterial lumen and plaque morphology, but also allows to directly visualize adventitial vasa-vasorum and carotid plaque neovascularization. This technique and its clinical implications in the unstable plaque identification are discussed in the present paper.
Neurovascular coupling (NVC), analysed by a control system approach, was shown to be unaffected by orthostatic challenge, but data is lacking regarding the mechanism of this interplay and the behaviour of other cerebrovascular reactivity parameters. We investigated the changes in different pressure–velocity models during functional transcranial Doppler (TCD), under different orthostatic conditions.
Thirteen healthy volunteers performed a reading test stimulation task in sitting, supine and head-up tilt (HUT) positions. CBF velocity was monitored with TCD in the posterior cerebral artery, and blood pressure was monitored with Finapres. Cerebrovascular resistance index (CVRi) was compared to a two-parameter model including resistance-area product (RAP) and critical closing pressure (CrCP), in the maximal and in the stable phases of flow response to visual stimulation.
All cerebrovascular resistance parameters decreased with visual stimulation but the magnitude of their variation in each orthostatic condition was not similar. From supine to HUT, CrCP variation decreased (both maximal and stable phase p = 0.001). CVRi variation increased from sitting to HUT positions (maximal p = 0.039; stable phase p = 0.033). RAP variation to visual stimulation did not change between the three positions (maximal p = 0.077; stable phase p = 0.188).
A 2-parameter model of vascular resistance provided better discrimination for the effects of posture on NVC as shown by the adaptive changes in CrCP with orthostatic challenge, in comparison with the classical use of CVRi. These findings suggest that although NVC seemed unaffected by orthostatic challenge, more complex vasoregulative mechanisms are activated in different orthostatic conditions that could potentially be of diagnostic or prognostic value.
Traumatic brain injury (TBI) is associated with the severest casualties from Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF). From October 1, 2008 the US Army Medical Department initiated a transcranial Doppler (TCD) ultrasound service for TBI patients; included patients were retrospectively evaluated for TCD-determined incidence of posttraumatic cerebral vasospasm and intracranial hypertension after wartime TBI. Ninety patients were investigated with daily TCD studies and comprehensive TCD protocol and published diagnostic criteria for vasospasm and raised intracranial pressure (ICP) were applied. TCD signs of mild, moderate and severe vasospasms were observed in 37%, 22% and 12% of patients, respectively. TCD signs of intracranial hypertension were recorded in 62.2%, five patients (4.5%) underwent transluminal angioplasty for post-traumatic clinical vasospasm treatment and 16 (14.4%) had cranioplasty. These findings demonstrate that cerebral arterial spasm and intracranial hypertension are frequent and significant complications of combat TBI, therefore daily TCD monitoring is recommended for their recognition and subsequent management.
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