Ultrasound (US) can noninvasively activate intact brain circuits, making it a promising neuromodulation technique. However, little is known about the underlying mechanism. Here, we apply transcranial US and perform brain mapping studies in guinea pigs using extracellular electrophysiology. We find that US elicits extensive activation across cortical and subcortical brain regions. However, transection of the auditory nerves or removal of cochlear fluids eliminates the US-induced activity, revealing an indirect auditory mechanism for US neural activation. Our findings indicate that US activates the ascending auditory system through a cochlear pathway, which can activate other non-auditory regions through cross-modal projections. This cochlear pathway mechanism challenges the idea that US can directly activate neurons in the intact brain, suggesting that future US stimulation studies will need to control for this effect to reach reliable conclusions.

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Current laboratory research in the field of abdominal aortic aneurysm (AAA) disease often utilizes small animal experimental models induced by genetic manipulation or chemical application. This has led to the use and development of multiple high-resolution molecular imaging modalities capable of tracking disease progression, quantifying the role of inflammation, and evaluating the effects of potential therapeutics. In vivo imaging reduces the number of research animals used, provides molecular and cellular information, and allows for longitudinal studies, a necessity when tracking vessel expansion in a single animal. This review outlines developments of both established and emerging molecular imaging techniques used to study AAA disease. Beyond the typical modalities used for anatomical imaging, which include ultrasound (US) and computed tomography (CT), previous molecular imaging efforts have used magnetic resonance (MR), near-infrared fluorescence (NIRF), bioluminescence, single-photon emission computed tomography (SPECT), and positron emission tomography (PET). Mouse and rat AAA models will hopefully provide insight into potential disease mechanisms, and the development of advanced molecular imaging techniques, if clinically useful, may have translational potential. These efforts could help improve the management of aneurysms and better evaluate the therapeutic potential of new treatments for human AAA disease.

Right heart failure is associated with increased systemic venous pressure, which can be diagnosed clinically with the findings of elevated jugular venous pressure, pulsatile liver and distinctive cardiac murmurs (precordial systolic). Severe tricuspid regurgitation (TR) has occasionally been known to lead to marked pulsation of varicose veins. We report three cases that were referred to the vascular clinic of Royal Perth Hospital in which the patients involved had unilateral (right leg) varicose veins and chronic venous ulcers. On clinical examination all three patients had pulsations along the course of the varicose long saphenous vein up to the mid calf. The main differential diagnosis was arterio-venous malformation, which was excluded by compression of the sapheno-femoral junction and demonstrating absence of pulsation in the long saphenous vein. A venous duplex scan showed a grossly incompetent sapheno-femoral junction with abnormal wave forms. Two of the cases were managed conservatively with compression dressing. The option of sapheno-femoral junction ligation was reserved in one patient who had unsettling cellulitis and oedema of the lower limb in spite of compression dressing and optimal conservative management. All three patients had improvement in ulcer size at 3-month follow up with compression therapy. This article highlights that in cases of right heart failure the venous pressures can be felt as low as the mid calf level and that can be a cause of the venous ulcers. There should be a high suspicion of right heart failure in patients with late onset venous insufficiency.

SummaryUltrasound (US) can noninvasively activate intact brain circuits, making it a promising neuromodulation technique. However, little is known about the underlying mechanism. Here, we apply transcranial US and perform brain mapping studies in guinea pigs using extracellular electrophysiology. We find that US elicits extensive activation across cortical and subcortical brain regions. However, transection of the auditory nerves or removal of cochlear fluids eliminates the US-induced activity, revealing an indirect auditory mechanism for US neural activation. US likely vibrates the cerebrospinal fluid in the brain, which is continuous with the fluid in the cochlea via cochlear aqueducts; thus, US can activate the ascending auditory pathways and other non-auditory regions through cross-modal projections. This finding of a cochlear fluidinduced vibration mechanism challenges the idea that US can directly activate neurons in the intact brain, suggesting that future US stimulation studies will need to control for this effect to reach reliable conclusions.peer-reviewed)

Ultrasound (US) has been shown to stimulate brain circuits, however, the ability to excite peripheral nerves with US remains controversial. To the best of our knowledge, there is still no in vivo neural recording study that has applied US stimulation to a nerve isolated from surrounding tissue to confirm direct activation effects. Here, we show that US cannot excite an isolated mammalian sciatic nerve in an in vivo preparation, even at high pressures (relative to levels recommended in the FDA guidance for diagnostic ultrasound) and for a wide range of parameters, including different pulse patterns and center frequencies. US can, however, reliably inhibit nerve activity whereby greater suppression is correlated with increases in nerve temperature. By prohibiting the nerve temperature from increasing during US application, we did not observe suppressive effects. Overall, these findings demonstrate that US can reliably inhibit nerve activity through a thermal mechanism that has potential for various health disorders, though future studies are needed to evaluate the long-term safety of therapeutic ultrasound applications.

European Journal of Trauma Ab stractAxillary artery injury after shoulder dislocation, without an associated bone fracture is very rare. Vascular injuries associated with brachial plexus lesions range in incidence from 27% to 44%. Management of axillary artery injury is mainly surgical and depends on the extent and the site of injury. The treatment of associated nerve injuries is more controversial. There is a scarcity of literature surrounding the association of injury to the brachial plexus, axillary artery and to the shoulder. The authors report a case of axillary artery associated with a delayed brachial plexus palsy and review the literature with the aim to identify the clinical pattern of this condition and to evaluate the outcome of neuropraxia after blunt axillary artery injury associated with anterior shoulder dislocation.

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