3D Reconstruction of the Clarified Rat Hindbrain Choroid Plexus

The choroid plexus (CP) acts as a regulated gate between blood and cerebrospinal fluid (CSF). Despite its simple histology (a monostratified cuboidal epithelium overlying a vascularized stroma), this organ has remarkably complex functions several of which involve local interaction with cells located around ventricle walls. Our knowledge of CP structural organization is mainly derived from resin casts, which capture the overall features but only allow reconstruction of the vascular pattern surface, unrelated to the overlying epithelium and only loosely related to ventricular location. Recently, CP single cell atlases are starting to emerge, providing insight on local heterogeneities and interactions. So far, however, few studies have described CP spatial organization at the mesoscale level, because of its fragile nature and deep location within the brain. Here, using an iDISCO-based clearing approach and light-sheet microscopy, we have reconstructed the normal rat hindbrain CP (hCP) macro- and microstructure, using markers for epithelium, arteries, microvasculature, and macrophages, and noted its association with 4th ventricle-related neurovascular structures. The hCP is organized in domains associated to a main vessel (fronds) which carry a variable number of villi; the latter are enclosed by epithelium and may be flat (leaf-like) or rolled up to variable extent. Arteries feeding the hCP emerge from the cerebellar surface, and branch into straight arterioles terminating as small capillary anastomotic networks, which run within a single villus and terminate attaching multiple times to a large tortuous capillary (LTC) which ends into a vein. Venous outflow mostly follows arterial pathways, except for the lateral horizontal segment (LHS) and the caudal sagittal segment. The structure of fronds and villi is related to the microvascular pattern at the hCP surface: when LTCs predominate, leaflike villi are more evident and bulge from the surface; different, corkscrew-like villi are observed in association to arterioles reaching close to the CP surface with spiraling capillaries surrounding them. Both leaf-like and corkscrew-like villi may reach the 4th ventricle floor, making contact points at their tip, where no gap is seen between CP epithelium and ependyma. Contacts usually involve several adjacent villi and may harbor epiplexus macrophages. At the junction between medial (MHS) and lateral (LHS) horizontal segment, arterial supply is connected to the temporal bone subarcuate fossa, and venous outflow drains to a ventral vein which exits through the cochlear nuclei at the Luschka foramen. These vascular connections stabilize the hCP overall structure within the 4th ventricle but make MHS-LHS joint particularly fragile and very easily damaged when removing the brain from the skull. Even in damaged samples, however, CP fronds (or isolated villi) often remain strongly attached to the dorsal cochlear nucleus (DCN) surface; in these fronds, contacts are still present and connecting “bridges” may be seen, suggesting the presence of real molecular contacts rather than mere appositions.

The Thickness of the facial Nerve Sheath Consistently Varies by Region in Its Intra-Tympanic Course on Cadaveric Study

Objectives: Iatrogenic removal of intra-temporal disease processes, such as cholesteatoma and keratosis obturans, can be challenging when the facial nerve (FN) is involved. Despite this concern about possible FN injury during these procedures, our clinical observation has been that the diseased growth can be cleaned quite easily from the vertical FN epineurium. Therefore, we designed a cadaveric protocol to measure thickness of the FN sheath (epineurium) in horizontal, second genu and vertical FN segments and to correlate these measurements with surgical management of FN disorders. Methods: Fifty non-fixated (wet) cadaveric temporal bones were dissected over 1 year’s time. The intra-temporal FN sheath epineurium was harvested from the mid-horizontal, second genu, and mid-vertical segments. Using a digital micrometric technique, the thickness of each sample was measured. Data analysis was performed using student’s two-tailed, dependent t-test. Results: Epineurial nerve sheath thickness was the least in the horizontal segment (mean 0.9 mm, range 0.040-0.140 mm), greater at the second genu (mean 0.19 mm, range 0.010-0.280 mm), and greatest in the vertical segment (mean 0.29 mm, range 0.170-0.570 mm). These differences were statistically significant. Conclusion: In cases of cholesteatoma and keratosis obturans involving the vertical FN, the disease process can be separated from the FN sheath because of the sheath thickness in this region. Disease in the horizontal segment involves a thinner sheath and separating the disease process from the nerve is more difficult in this area.

Temporary Clipping of the Intracavernous Internal Carotid Artery: A Novel Technique for Proximal Control

BACKGROUND Securing proximal control in complex paraclinoid aneurysm surgery through traditional techniques may be challenging and risky in certain situations. Advancements of anatomical knowledge of the cavernous sinus (CS) and hemostasis have made it more accessible as a surgical option. OBJECTIVE To describe the technique of temporary clipping of the horizontal segment of the intracavernous internal carotid artery (IC-ICA) in preparation for permanent clipping of complex paraclinoid aneurysms. METHODS Through an extradural pretemporal approach, the lateral wall of the CS is exposed. The dura between the trochlear nerve and V1 is opened, and access is made to the horizontal segment of the IC-ICA. After circumferential dissection, the temporary clip can be introduced to the artery, and the extradural clinoidectomy can be continued under secured proximal control. RESULTS Seven patients with complex paraclinoid aneurysms were treated between May 2013 and May 2016 by the senior author. Temporary clipping of the IC-ICA was performed in all cases. Average time to achieve proximal control was 22.6 min (22.6 ± 13.8). One patient developed transient oculomotor palsy postoperatively. There were no other complications. CONCLUSION When the exposed clinoidal segment of the internal carotid artery does not offer sufficient proximal space for temporary clipping, the extradural approach can be extended to the horizontal portion of the IC-ICA. In our experience, this technique is a quick, reliable, and safe alternative to the classical modalities of temporary occlusion.

Abstract TP85: The Characteristics of Diffusion Weighted Image Patterns in Different Potential Embolic Source

Introduction: Few studies have focused on the characteristics of diffusion weighted image (DWI) pattern in different embolic stroke. Hypothesis: Studying the DWI pattern in patients with embolic stroke of determined source may help presume the cause of ESUS. Methods: From a prospective registry of 1,764 consecutive patients with acute ischemic strokes , we selected 422 patients with embolic stroke of determined source comprising of 4 groups as follows. 1: continuous atrial fibrillation (cAf) (n=232), 2: paroxysmal Af (pAf) (n=99), 3: paradoxical embolism associated with the foramen ovale (PXE) (n=48) and 4: aortogenic embolism associated with aortic atheroma (≥4mm, ulcer or mobile) (AoE) (n=56). The DWI patterns were classified as follows. First, cortical infarcts were classified according to the affected area of middle cerebral artery (MCA) segments such as M1: the horizontal segment, M2: after the bifurcation segments within the Sylvian fissure and M4: terminal cortical branch. Among patients with M1, pure striatocapsular infarction (SCI) was identified. Moreover, patients with the M2 and the M4 were divided into 2 groups including parietal ascending branches and temporal descending branches. Second, cortical and subcortical small multiple infarcts (<20mm) (sMI) were identified. Finally, infarcts in the anterior cerebral artery (AC) and the posterior circulation (PC) were identified. Results: The distribution of the DWI patterns in the 4 groups (cAf: pAf: PXE: AoE, %) are as follows: M1 (n=100) (76.0: 17.0: 7.0: 0), M2 (n=118) (59.3: 30.5: 7.6: 2.5), M4 (n=50) (50.0: 26.0: 18.0: 6.0), SCI (n=20) (2.1: 4.0: 14.5: 0), sMI (n=49) (18.3: 16.3: 18.3: 46.9), AC (n=13) (46.1: 46.1: 0: 7.6), and PC (n=92) (50.0: 20.6: 15.2: 14.1). Among 162 patients with M2 and M4 infarction, there were 57 involvements of descending branches (35.1%), comprising of 38 patients (41.7%) in cAf, 17 (34.6) in pAf, 1 (6.2) in PXE and 1(7.4) in AoE. Conclusions: Infarct sized was large in the Af groups. The involvement of inferior division of the MCA was exclusively found in the Af groups. The SCI was most prevalent in the PX. Multiple small scattered pattern was characteristically found in the AoE. The different DWI patterns relatively well associated with different embolic source.

Technological Structures for Air Cooled Condensers

This paper summarizes the knowledge and results obtained in the field of designing technological platforms for energy industry. Optimal solution of the layout of elements and material of a number of technological platforms with a specific number of modules was searched. Technological platforms are the main supporting structure of the air-cooled condensers (ACC), which ensure cooling of plants. The fundament of the solution is based on the schema that the platform is composed from the at least one standardized bed containing the supporting surface equipped with the supporting columns and at least one horizontal segment for the condenser exchanger support. The platform structure must ensure sufficient spatial rigidity and stability and ACC functionality. Design requirements are defined both by size and weight of each single module of condenser and the total number of modules in assembly.

Herniated Proximal Marker of the Stent into the Meningohypophyseal Trunk after Stent-Assisted Coil Embolization for Intracranial Aneurysms

The SolitaireTM AB Neurovascular Remodeling Device (ev3, Irvine, CA, USA) is used to retain coils within an aneurysm, reducing the risk of embolic complications from coil herniation into the parent artery. Stents are deployed after confirming the optimal position of the stent markers across the aneurysm to avoid entry into perforators or branching arteries. Stent marker position is very important to prevent perforating or branching artery infarction. We performed stent-assisted coil embolization using the Solitaire AB stent to treat 2 aneurysms simultaneously. After successful coil embolization, we detached the Solitaire stent in the usual manner. However, the proximal stent marker, which was located at the horizontal segment of the cavernous internal carotid artery, moved into the meningohypophyseal trunk and occluded it. Although the distal markers were positioned optimally, we did not expect the proximal marker to be in the position where it was located. Fortunately, cranial nerve dysfunctions and pituitary deficiency did not develop. It is important to prevent ischemic injury by occlusion of the perforators or branching vessels that can be caused by malpositioned stent markers. We consider where the proximal marker of the stent might be located after detachment.

Unemployment: Walras’s voluntary and Keynes’s involuntary

This paper shows that Keynes’s involuntary unemployment derives from Walras’s voluntary unemployment by means of changing the characteristic of the aggregate supply curve (function) of labour. On the one hand, when the original aggregate supply function is a strong-ly increasing function, as in Walras’s approach, there might only be voluntary unemployment, and its magnitude is the difference between the available quantity of labour and the equilibrium point. On the other hand, if the supply curve of labour is a weakly increasing one, which means that the supply function may have a horizontal segment, then there might be involuntary unemployment if the equilibrium point is located be-tween boundary points of the horizontal segment, and the magnitude of involun-tary unemployment is the difference between the right boundary point of the hori-zontal segment and an equilibrium point. According to Walras’s approach, “forced unemployment” might also might be considered, which is the result of the intervention of external forces (government, monopoly, trade unions, and so on) into the market, and is therefore a disequilibrium phenomenon.