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We describe a novel patient-positioning device for dynamic CT myelography. Dynamic CT myelography requires angling the patient's spine to distribute dense contrast along the dependent thecal sac. The proposed device is constructed of a low-density reinforced polymer frame and can be raised or lowered to various heights with a hand-operated mechanism, allowing precise adjustment of the spinal angle and control of the contrast bolus, increasing the safety, reproducibility, and sensitivity of dynamic CT myelography., (© 2023 by American Journal of Neuroradiology.)

Egocentric sampling of networks selects a subset of nodes ("egos") and collects information from them on themselves and their immediate network neighbours ("alters"), leaving the rest of the nodes in the network unobserved. This design is popular because it is relatively inexpensive to implement and can be integrated into standard sample surveys. Recent methodological developments now make it possible to statistically analyse this type of network data with Exponential-family Random Graph Models (ERGMs). This provides a framework for principled statistical inference, and the fitted models can in turn be used to simulate complete networks of arbitrary size that are consistent with the observed sample data, allowing one to infer the distribution of whole-network properties generated by the observed egocentric network statistics. In this paper, we discuss how design choices for egocentric network studies impact statistical estimation and inference for ERGMs. The design choices include both measurement strategies (for ego and alter attributes, and for ego-alter and alter-alter ties) and sampling strategies (for egos and alters). We discuss the importance of harmonising measurement specifications across egos and alters, and conduct simulation studies to demonstrate the impact of sampling design on statistical inference, specifically stratified sampling and degree censoring.

Purpose: The recurrent artery of Heubner (RAH) is a very fascinating artery for various reasons. The first one is its early development in the embryologic and phylogenic life. The second one is the discrepancy between its diameter and its functional importance and the last but not least reason is the many variations of origin and course of this artery., Methods: For more than a century, numerous studies furnished important information about variations in origin, course, and parenchymal territory of the RAH. The most important anomaly concerning the RAH is the accessory middle cerebral artery and well-illustrates the complexity of its embryologic development., Conclusion: For these reasons, authors provide a review of anatomical variations of this artery that could be encountered with a particular attention given to the history and embryological knowledge.

Background: Ultrasound (US) examination of the eye can be used to detect and monitor elevated intracranial pressure (ICP) and its consequences. Elevated ICP is transmitted to the contiguous optic nerve and its sheath (dura mater), thus underlying the development of papilledema and a widened sheath diameter. The US measurement of the optic nerve sheath diameter (ONSD) has previously been validated to diagnose and monitor raised ICP. The occurrence of vitreous hemorrhage in association with subarachnoid hemorrhage (SAH)-i.e., Terson syndrome-can also be easily diagnosed using ophthalmic US. Because of its relevance in anesthesia and critical care, we describe how to perform the technique illustrated by two cases., Case Presentations: A 72-yr-old man with hydrocephalus secondary to a SAH developed raised ICP following the removal of an external ventricular drainage (EVD) system. Daily ONSD measurements using handheld US allowed us to diagnose and monitor the progression and resolution of the intracranial hypertension following the placement of a second EVD system. We also describe the steps used to obtain ONSD measurements during the ophthalmic US examination of a 53-yr-old woman who presented with a stage IV SAH with concomitant bilateral vitreous hemorrhages or Terson syndrome., Conclusion: Ophthalmic US using a handheld device to measure and monitor ONSD at the bedside is useful in diagnosing and monitoring the progression of intracranial hypertension following EVD removal in a patient with hydrocephalus secondary to SAH. Ophthalmic US can also be used to identify concomitant vitreous hemorrhage that is associated with a worse prognosis.

Purpose: The ophthalmic artery (OA) has one of the most complex anatomy and the most fascinating embryological development., Methods: The complexity of the embryologic development of the OA resides in the implication of three different embryological systems: the carotid system, the stapedial system, and the ventral pharyngeal system., Results: This explains very well the numerous variations in origin of the OA and the importance of vascular anastomoses developed with branches of the external carotid artery and with the middle meningeal artery., Conclusion: In this review, authors propose a comprehensive description of different hypotheses on the embryologic development of the OA and, in a second part, explain all anatomical variations and clinical implications of this artery.

Background: Aneurysmal subarachnoid hemorrhage (SAH) is a catastrophic disease with devastating consequences, including a high mortality rate and severe disabilities among survivors. Inflammation is induced following SAH, but the exact role and phenotype of innate immune cells remain poorly characterized. We investigated the inflammatory components of the early brain injury in an animal model and in SAH patients., Method: SAH was induced through injection of blood in the subarachnoid space of C57Bl/6 J wild-type mice. Prospective blood collections were obtained at 12 h, days 1, 2, and 7 to evaluate the systemic inflammatory consequences of SAH by flow cytometry and enzyme-linked immunosorbent-assay (ELISA). Brains were collected, enzymatically digested, or fixed to characterize infiltrating inflammatory cells and neuronal death using flow cytometry and immunofluorescence. Phenotypic evaluation was performed at day 7 using the holding time and footprint tests. We then compared the identified inflammatory proteins to the profiles obtained from the plasma of 13 human SAH patients., Results: Following SAH, systemic IL-6 levels increased rapidly, whereas IL-10 levels were reduced. Neutrophils were increased both in the brain and in the blood reflecting local and peripheral inflammation following SAH. More intracerebral pro-inflammatory monocytes were found at early time points. Astrocyte and microglia activation were also increased, and mice had severe motor deficits, which were associated with an increase in the percentage of caspase-3-positive apoptotic neurons. Similarly, we found that IL-6 levels in patients were rapidly increased following SAH. ICAM-1, bFGF, IL-7, IL-12p40, and MCP-4 variations over time were different between SAH patients with good versus bad outcomes. Moreover, high levels of Flt-1 and VEGF at admission were associated with worse outcomes., Conclusion: SAH induces an early intracerebral infiltration and peripheral activation of innate immune cells. Furthermore, microglia and astrocytic activation are present at later time points. Our human and mouse data illustrate that SAH is a systemic inflammatory disease and that immune cells represent potential therapeutic targets to help this population of patients in need of new treatments.

Background and Purpose: Moyamoya disease is a chronic neurovascular steno-occlusive disease of the internal carotid artery and its main branches, associated with the development of compensatory vascular collaterals. Literature is lacking about the precise description of these compensatory vascular systems. Usually, the posterior circulation is less affected, and its vascular flow could compensate the hypoperfusion of the ICA territories. The aim of this study was to describe these natural connections between the posterior cerebral artery and the anterior cerebral artery necessary to compensate the lack of perfusion of the anterior cerebral artery territories in the Moyamoya population., Materials and Methods: All patients treated for Moyamoya disease from 2004 to 2018 in 4 neurosurgical centers with available cerebral digital subtraction angiography were included. Forty patients (80 hemispheres) with the diagnosis of Moyamoya disease were evaluated. The presence of anastomoses between the posterior cerebral artery and the anterior cerebral artery was found in 31 hemispheres (38.7%)., Results: Among these 31 hemispheres presenting with posterior cerebral artery-anterior cerebral artery anastomoses, the most frequently encountered collaterals were branches from the posterior callosal artery (20%) and the posterior choroidal arteries (20%). Another possible connection found was pio-pial anastomosis between cortical branches of the posterior cerebral artery and the anterior cerebral artery (15%). We also proposed a 4-grade classification based on the competence of these anastomoses to supply retrogradely the territories of the anterior cerebral artery., Conclusions: We found 3 different types of anastomoses between the anterior and posterior circulations, with different abilities to compensate the anterior circulation. Their development depends on the perfusion needs of the territories of the anterior cerebral artery and can provide the retrograde refilling of the anterior cerebral artery branches., (© 2019 by American Journal of Neuroradiology.)

Multilevel network data provide two important benefits for ERG modeling. First, they facilitate estimation of the decay parameters in geometrically weighted terms for degree and triad distributions. Estimating decay parameters from a single network is challenging, so in practice they are typically fixed rather than estimated. Multilevel network data overcome that challenge by leveraging replication. Second, such data make it possible to assess out-of-sample performance using traditional cross-validation techniques. We demonstrate these benefits by using a multilevel network sample of classroom networks from Poland. We show that estimating the decay parameters improves in-sample performance of the model and that the out-of-sample performance of our best model is strong, suggesting that our findings can be generalized to the population of interest.

Background: Due to their important size and complex localization, the management of thoracic dumbbell tumors is challenging, frequently requiring the need for an anterior approach. Our study aims to first report the feasibility and safety of a single-stage posterior minimally invasive procedure in achieving complete resection of voluminous thoracic dumbbell tumors., Methods: We retrospectively reviewed the medical records of five consecutive patients, who underwent the minimally invasive resection of a type III thoracic dumbbell tumor in our institution between March 2007 and March 2012. There were two men and three women, with a mean age at diagnosis of 57 years (range 41-68 years). After the placement of a non-expandable tubular retractor under fluoroscopic control, a costotransversectomy was achieved. By moving the retractor in all directions, the tumor was largely exposed and resected with the cavitron ultrasonic surgical aspirator. Clinical and radiological monitoring was performed before discharge, at 6 months, 1 year and 2 years., Results: No major intraoperative complication was reported. Gross total resection was achieved in four patients. The mean operative time was 219 mins (range 75-540 mins) and the mean estimated blood loss was 230 ml (range 50-500 ml). No postoperative complication was reported. The mean length of hospital stay was 3.6 days (range 2-6 days) and all patients were discharged home. Histological analysis confirmed the diagnosis of grade 1 schwannoma in four patients and revealed a hemangiopericytoma in one patient. No tumor recurrence was noted with a mean follow up period of 46 months (range 32-54 months)., Conclusion: Thoracic dumbbell tumors can be safely and completely resected using a single-stage minimally invasive procedure. The costotransversectomy can be performed through a non-expandable retractor allowing sufficient access to all parts of the tumor.

We describe a misleading case of a partially occluded A1 segment duplication that mimicked an ACoA aneurysm on computed tomography angiography and conventional angiography and led to surgical intervention. The location of such an anomaly at the ACoA on the side of least hemodynamic stress may provide a clue to recognizing this variant. [ABSTRACT FROM AUTHOR]

Aneurysms rarely occur at the choroidal branch of the posterior inferior cerebellar artery (PICA) and their pathogenesis is not well understood. We report such a case and review the literature. A 69-year-old female was admitted for a sudden onset of severe headache with nausea and vomiting. Soon after arrival, she became less responsive. CT of the head revealed an intraventricular haemorrhage (IVH) predominantly in the fourth and third ventricles without subarachnoid hemorrhage and associated with hydrocephalus. Cerebral angiography demonstrated an aneurysm at the choroidal branch of the PICA. The aneurysm was resected through a bilateral suboccipital craniotomy. The patient made a remarkable recovery. The literature describes five other cases of aneurysms arising from a choroidal branch of the PICA. Hypertension was a common finding in this population. In summary, aneurysms arising from a choroidal branch of the PICA are rare. Hypertensive vessel damage might be a major factor in their pathogenesis. We propose that the rupture of a hypertensive aneurysm might account for some isolated spontaneous IVH. [ABSTRACT FROM AUTHOR]