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Neuropathy of the lateral cutaneous branch of the iliohypogastric nerve (LCBIN) may represent a differential diagnosis for greater trochanteric pain syndrome (GTPS). Ultrasound-guided neural blockade of the LCBIN may lead to diagnosis of this neuropathy. The aim of this study was to evaluate the accuracy of ultrasound-guided nerve block in cadavers and to present a first clinical case series of patients with neuropathy of the LCBIN where the workup for GTPS remained unremarkable. Ultrasound-guided nerve block led to pain relief in these patients, indicating LCBIN neuropathy. First, ultrasound-guided injections at the LCBIN were performed bilaterally in 24 fresh, non-frozen, non-embalmed body donors. Accuracy and nerve localization were validated by anatomic dissection. Second, a clinical case series of nine patients with suspected GTPS who underwent ultrasound-guided diagnostic LCBIN blockade was retrospectively analyzed. Ultrasound-guided injections at the LCBIN yielded 91.7% accuracy (95% confidence interval: 0.80–0.98). On the right side the nerve was found within a range of 3–14 cm from the anterior superior iliac spine, and within a range of 7–15 cm on the left side. This clinical case series indicates that ultrasound-guided blockade at the LCBIN provides temporary pain relief and indicates the presence of LCBIN neuropathy. Ultrasound has demonstrated high accuracy for localization and injection guidance in the examination of LCBIN. Ultrasound-guided injection of local anesthetics may help to identify LCBIN neuropathy as a differential diagnosis in patients with suspected GTPS. [ABSTRACT FROM AUTHOR]

Ultrasound as a diagnostic tool in thoracic outlet syndrome (TOS) is becoming increasingly important. The aim of this study was to investigate the diagnostic value of ultrasound in detecting the axillary arch, an ancillary muscle potentially causing TOS. Two hundred upper limbs of 100 fresh, non-frozen, non-embalmed body donors were screened for axillary arches. Sonographic findings were validated by anatomic dissection. Twelve axillary arches were found in 200 upper extremities, corresponding to a prevalence of 8.0% per individual and 6.0% per upper extremity investigated. Ultrasound had low diagnostic performance in identifying axillary arches, with a sensitivity of 66.7% and specificity of 95.7%. There was a tendency to identify more easily arches consisting of purely muscle tissue. Axillary arch thickness, its cross-sectional area and the predominant tissue type were associated with compression of the neurovascular bundle during shoulder elevation. Ultrasound seems to have limited potential to identify axillary arches. However, arches consisting predominantly of muscle tissue may be identified more easily and were associated with compression of neurovascular structures, thus potentially causing symptoms. Further clinical trials are needed to clarify the true value of ultrasound in patients with symptoms of TOS. [ABSTRACT FROM AUTHOR]

The literature on exoscope use in cerebrovascular neurosurgery is scarce, mainly comprising small case series and focused on visualization quality and ergonomics. As these devices become widely used, direct comparison to the operating microscope regarding efficacy and patient safety is necessary. Fifty-two consecutive clipping procedures, performed by 1 senior vascular neurosurgeon, were analyzed. Either an operating microscope with a mouth switch (25 cases with 27 aneurysms; 13 ruptured) or a three-dimensional exoscope with a foot switch (27 cases with 34 aneurysms; 6 ruptured) were used. Durations of major surgical stages, number of device adjustments, numbers of clip repositionings and clips implanted were extracted from surgical videos. Demographic data, imaging characteristics, clinical course and outcomes were extracted from digital patient records. Duration of surgery and different stages did not differ between devices, except for final site inspection. The number of device adjustments was higher with the exoscope. With progressive experience in exoscope use, the number of device adjustments increased significantly, whereas surgery duration remained unchanged. Favorable outcome (modified Rankin Scale score 0–2) was observed in 80% and 88% of patients in the microscope and exoscope groups, respectively. Ischemic events were found in 2 patients in each group; no other complications occurred. In aneurysm clipping, three-dimensional exoscopes are noninferior to operating microscopes in terms of surgery duration, safety, and outcomes, based on our limited series. Progressive experience enables the surgeon to perform significantly more device adjustments within the same amount of surgical time. [ABSTRACT FROM AUTHOR]

Three major arteries supplying the ulnar nerve in the cubital tunnel are commonly known. However, their vascular territories (angiosomes) have not been described yet. Contrast-enhanced ultrasound was used to identify the angiosomes of posterior ulnar recurrent artery, inferior ulnar collateral artery and superior ulnar collateral artery in 20 fresh, non-frozen human body donors. The arteries were cannulated, and physiologic blood flow was simulated. Contrast agent was applied in each vessel in a randomized sequence, and the length of the contrast-enhancing ulnar nerve segment was measured by a radiologist blinded to the sequence. The angiosome of the posterior ulnar recurrent artery overlaps both other angiosomes. It fully covers the cubital tunnel in 63.6% of specimens. In addition, collateral flow via nerve and muscle branches of the arterial anastomotic network around the elbow (rete articulare cubiti) partly maintains the intra-neural blood flow in the absence of a vascular pedicle. The posterior ulnar recurrent artery is the dominant nutrient vessel of the ulnar nerve in the cubital tunnel. A potential watershed zone exists proximal to the Osborne ligament. Knowledge of these angiosomes may advance surgery of the ulnar nerve in the cubital tunnel. [ABSTRACT FROM AUTHOR]

Ice accretion and blockages in aircraft fuel systems continue to be of interest as a result of their influence on system design and alternative fuel synthesis as well as their role in aviation incidents and accidents. Ice accumulation tests are performed in a recirculating fuel system with Jet A-1 fuel. Removable stainless steel test pipes and variable flow rates allow for the examination of ice accretion with variation of pipe diameter and Reynolds number in a repeatable manner. The flow loop is installed in an altitude chamber capable of −50 °C and the experiments involve full-scale flow components. Temperature of the flow loop is controlled with an initial −11 °C/h cooling rate followed by a constant temperature test time. Instantaneous measurements of pressure drop along the test pipe are used to characterize ice accretion. Additionally, end-view imaging of the test pipes is performed to characterize the size and quality of the accreted ice. Normalized pressure drop is seen to increase nearly linearly with time for the range of Reynolds numbers and temperatures tested. Approximate ice accretion rates are extracted from the time varying pressure drops assuming the ice accumulation changes the pipe surface roughness. Accreted ice layer growth rates as high as 0.91 ± 0.12 mm/hr are seen at low flow rate conditions (Re ∼ 4000 , −10.5 °C) and decrease with increasing Reynolds number. Growth rates at −7 °C and −19 °C are ∼25% and ∼1.5% of the −10.5 °C growth rate, respectively, and follow the same Reynolds number trend. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study of the flammability properties of PMMA at low pressures and oxygen concentrations was performed. The work was motivated by the importance of these effects on fire safety in the aviation industry. Measurements were obtained in a mass loss calorimeter inside a large 10m3 pressure vessel capable of reaching pressures as low as 0.1atm. The PMMA flammability was characterized by measuring the burning rate and the time to ignition of small test samples. These were ignited and burned under different external heat fluxes, total pressures and oxygen concentrations. The combined effects of pressure and oxygen concentration on the burning rate, combustion flow field, and ignition were evaluated. Results showed that at low pressure, the burning rate was less intense with a decrease in the mass loss rate. However, the reduction in pressure caused a shortened ignition delay time. Experimental measurements were compared with a simple analytical model showing good agreement. The results also show how pressure and oxygen concentration contributed to the heat transfer from the flame. The model revealed that a single function in oxygen and pressure could account for both flame radiative and convective effects. As a result, a power law fit was obtained for the relation of the combined pressure and oxygen effect on the burning rate. This correlation shows a good agreement with the measurements and predicts the burning rate behavior for the full range of pressure and oxygen tests. [Copyright &y& Elsevier]