Microsurgical anatomy of the medial tentorial artery of Bernasconi–Cassinari

Objective  

In the current literature, there is a lack of detailed map of the origin, course and relationships of the medial tentorial artery (MTA) of Bernasconi–Cassinari often implicated in various diseases such as dural arteriovenous fistulas of the cranial base, stenotic lesions of the ICA, saccular infraclinoid intracavernous aneurysms and tentorial meningiomas.     

Microsurgical anatomy of the vein of Labbé

Objective  

Venous drainage of the temporal lobe is of great importance in various neurosurgical and combined skull base approaches. The most significant draining vein of the temporal lobe is the inferior anastomotic vein (vein of Labbé). The purpose of this study was to examine the detailed anatomy and variations of the vein of Labbé (VL) from microsurgical perspective.     

Experimental investigation of the stent–artery interaction

Abstract

It is well acknowledged that stent implantation causes abnormal stretch and strains on the arterial wall, which contribute to the formation and progression of restenosis. However, the experimental characterization of the strain field on the stented vessel is scant. In this work, the balloon-expandable stent implantation inside an artery analogue was captured through two high-speed CCD cameras. The surface strain maps on the stented tube were quantified with a 3-D digital image correlation technique. The strain history at one specific reference point illustrated three stenting phases, including balloon inflation, pressurization and deflation. The surface strain distributions along one axial path were obtained at various time points to demonstrate the stent–vessel interactions. The radial wall thickness reduction history was used to evaluate the pressure–diameter relationship for the balloon. Results indicated that the expansion process of the balloon was significantly altered by the external loadings from both the stent and artery analogue. In addition, the repeatability of the stenting experiments was demonstrated through two tests with a change of 5% in the stent-induced maximum first principal strain. Moreover, a computational model of the stenting procedure was developed to recapture the stenting experiments. Comparison between experiments and simulation showed a difference of 7.17% in the first principal strain averaged over the high strain area. This indicated the validation of the computational framework, which can be used to investigate the strain or stress field throughout the computational domain, a feature that is not affected by experimental techniques.     

Connection types between the spinal root of the accessory nerve and the posterior roots of the C2–C6 spinal nerves

Purpose  The aim of this study was to demonstrate the connection types and frequency between the accessory nerve and the posterior roots of the C2–C6 cervical nerves. Methods  The cranial cervical regions of 49 specimens from 27 human cadavers were used for the present study under an operating microscope. Results  Five different connection types between the accessory nerve and the posterior roots of the cervical nerves were recorded and photographed (types A–F). One of these types was not described previously in literature (type F). All connections between the posterior roots of the C2–C6 spinal nerves and the accessory nerve were at the level of the C2 segment. Type B was the most frequently seen type in our series. One of the rootlets of the cervical posterior root joined the accessory nerve without a connection to the spinal cord in type B. Conclusions  The clinical importance of these connections is especially noticed during the radical neck dissection as it may lead to the development of the shoulder-arm syndrome.     

Atherosclerosis in the vertebral artery: an intrinsic risk factor in the use of spinal manipulation?

The presence of atherosclerotic plaques and their influence on the vertebral artery is of clinical importance within the scope of spinal manipulation. Manipulation may stimulate the development of atherosclerotic plaques, could detach an embolus with ensuing infarction, injure the endothelium or may directly cause a dissection in the presence of atherosclerotic plaques. In order to identify the sites and frequency of atherosclerotic plaques and to determine its relation to the tortuous course of the vertebral artery, a cadaveric study was performed. The vertebral arteries of 57 human cadavers were studied. The vertebral artery was virtually divided into four segments: the pre-vertebral (V1), the vertebral (V2), the atlanto-axial (V3), and the intracranial segment (V4). Abnormalities in the origin and course of the vertebral artery were noted, along with any associated osseous, or cartilaginous anomalies in the neck. After dissection, the artery was opened and macroscopically screened for the presence of atherosclerotic plaques. In 22.8% of the cases, no atherosclerotic plaques were present. In 35.1% of the cases, the atherosclerotic plaques were unilateral, of which 60.0% was on the left side, 40.0% on the right side, and in 42.1%, the occurrence was bilateral. Atherosclerotic plaques were significantly more present in the V3 segment than in the V1 (0.007) and V2 segment (0.049). In the V1 (P=0.008) and V2 segment (P=0.002), there was a correlation between a tortuous course of the vessel and the occurrence of atherosclerotic plaques. In individuals with marked atherosclerotic disease, stretching and compression effects of rotational manipulative techniques on atherosclerotic vessels impose a further risk factor for vertebrobasilar insufficiency. As direct evidence of atherosclerotic plaques are rarely available, therapists should avoid manipulative techniques at all levels of the cervical spine in the presence of any indirect sign of atherosclerotic disease or in the presence of calcified arterial walls or tortuosities of the vessels visible on routinely available X-ray images of the cervical or thoracic spine. It is strongly recommended, that if any doubt exists about the nature of a clinical presentation, vigorous manual procedures should be avoided until either the diagnosis is definitive or gentle manual therapy has proven effective.     

Tracking The plasticity of the spinal cord

SincethefirstpaperreportedbyAmericanscientistsLiuandChambers(1958)ontheplasticityofthespinalcordofcatunderlightmicroscope,thecapacityforphysio-logicalandmorphologicalchangehasbeenknownincentralnervoussystem(CNS)ofmammaliananima1s.Inrecentyears,manyneurosc…     

Effect of the IABP on the renal artery bloodflow

1.IntruductionTheintra-aorticballoonpumping(IABP)isanimportantmethodtoassisttheheartintheclinic.ButtheinfluenceofIABPonrenalarteryflowwasvariableindifferentexperimentsanddifferentconclusionsweredrawnfromdifferentexperimentsl[1.2].2.MaterialandMethodsTwentyadultdogsofeithersexweighing15-20kgwereanesthetized.Theaorticpressure(AoP),therenalarterybloodpressure(RAP),theaorticbloodflow(ABF),thatisthecardiacoutput(CO),andtheleftrenalarterybloodflow(RBF)wererespectivelymeasured.ProtocolifAnl…     

Duplication of the left vertebral artery in a patient with dissection of the right internal carotid artery and Ehlers–Danlos syndrome: case report and review of the literature

Duplication of the left vertebral artery was observed in a 43-year-old Caucasian male with dissection of the right internal carotid artery during multidetector 64-row computer tomography and Doppler ultrasonography B-flow mode. Both duplicated segments arose from the left subclavian artery and united at levels C5–C6 to form a single vessel. The presented case describes precisely the origin and diameter of both vertebral arteries. Additionally, after all procedures associated with diagnosis and treatment of the patient, Ehlers–Danlos syndrome type IV was diagnosed. The lumen of the duplicated vertebral artery was smaller than normal; it can be concluded that this variant has clinical implications and should be taken into consideration when vertebral arteries need catheterization.     

The anatomy of the Göttingen minipig hypothalamus

The microscopic organization of the Göttingen minipig (sus scrofa) hypothalamus was studied using Nissl stain, acetylcholinesterase histochemistry, and immunohistochemical staining for calretinin, tyrosin hydroxylase, oxytocin, vasopressin, and orexin A.Mediolaterally the minipig hypothalamus can be divided into three cytoarchitectonic distinct longitudinal zones. The periventricular longitudinal zone comprises the supraoptic, paraventricular, median preoptic, anteroventral periventricular, suprachiasmatic and arcuate nuclei.The medial longitudinal zone includes the prominent medial preoptic, ventromedial, dorsomedial and medial mammillary nuclei. Together with the anterior hypothalamic area, they can be further divided into distinct subregions. The dorsal and posterior hypothalamic areas and the retromammillary and lateral mammillary nuclei are cyto- and chemoarchitectonically distinct but cannot be further divided into subregions.The cell sparse, fiber rich lateral longitudinal zone comprises the lateral preoptic and lateral hypothalamic area as well as the perifornical, lateral tuberal and tuberomammillary nuclei.The findings presented here indicate that the cyto- and chemoarchitecture of the Göttingen minipig hypothalamus is comparable to that of rat, landrace pig, monkey, and human and that the Göttingen minipig may be well suited for future, non-primate, large mammal, hypothalamic research.     

Postural influence on the neutral zone of the porcine cervical spine under anterior–posterior shear load

Segmental instability, characterized by excessive or aberrant movement of the vertebrae can be assessed quantitatively using mechanical characteristics within a region of minimal resistance called the neutral zone. The diagnosis of instability is often used to decide whether or not to surgically fuse the vertebrae. Alterations in flexion/extension posture cause changes in both contact area and spacing between articulating facets that may lead to changes in the mechanical response of the functional spinal unit (FSU) within the neutral zone. This investigation quantified neutral zone (NZ) length under anterior and posterior shear loading and the influence of posture on the shear NZ characteristics of the vertebral joint. Thirty porcine cervical FSUs (15 C34 and 15 C56) were tested. Endplate area was calculated from measurements of the exposed endplates while facet angles were measured from X-rays taken in the transverse plane. Specimens were exposed to a 300 N compressive preload followed by a test to determine flexion/extension NZ limits. These limits were used as target angles during shear passive tests performed in extended and flexed postures. Displacement rate during shear passive tests was 0.2 mm/s and five cycles of anterior–posterior shear were performed to a target of ±400 N in a randomized order of extended, neutral and flexed postures. Shear NZ length and average stiffness were quantified. Stiffness within the shear NZ was 67 N/mm in the neutral posture. Extended postures produced a 37% (p < 0.0001) increase in shear stiffness within the NZ compared to both flexed and neutral postures. Posture did not influence shear NZ length. Therefore, a true region of zero stiffness does not exist during shear loading with a baseline compressive load. Neutral zone length for the porcine FSU exposed to shear load was not influenced, despite known changes in facet articulation, by changing posture. Average stiffness increased likely as a result of increased contact area and force in extension. The results from this investigation demonstrate that postural deviation of the vertebral joint is not likely a significant confounding factor when assessing segmental stability.     

Quantitative freeze-fracture analysis of the frog neuromuscular junction synapse – II. Proximal–distal measurements

Neurotransmitter release from different parts of frog motor nerve terminals is often non-uniform. There is a decrease in release efficacy from the distal regions of frog motor nerve terminal branches. Since release is thought to occur near the double arrays of large intramembranous particles that constitute the pre-synaptic active zones (AZs), we have examined quantitatively the proximal–distal distribution of AZ structure, using a novel freeze-fracture technique that produces replicas of large fractions of terminals, including the region of nerve entry. This enables us to know the proximal–distal orientation of each branch. From 23 end-plates we have obtained fractures of 72 branches. For 27 of these branches we have obtained continuous fractures both greater than 25 m in length and with sufficient information to determine their proximal–distal polarity. Only a few of these branches showed a marked distal decrease in AZ length/unit length of terminal, while several junctions had short regions (5–10 m), either proximally or distally, that exhibited amounts of AZ that were substantially greater or smaller than the mean value for that terminal branch. The terminal area, post-synaptic gutter width and nerve terminal width all exhibit some distal decline concomitant with the distal tapering of nerve terminal branches. AZ length tends to have the least decline compared to the other parameters. Thus, the vast majority of frog motor nerve terminal branches do not display a significant proximal-distal gradient in the amount of AZ structure/m terminal length. The present data do not provide an obvious ultrastructural correlate for the distal decline in transmitter release that some authors have observed.     

How T'reg-ulate healing of the injured spinal cord?

Regulatory T cells (Tregs) are important for limiting inflammation-dependent damage in neural tissue. However, Tregs have also been shown to inhibit neural repair associated with type 2 (anti-inflammatory/wound healing) immune responses. Recently, it was demonstrated that Sirtuins, a family of proteins that contribute to the control of cellular responses to metabolic stimuli, influence the functions of Tregs. Specifically, SIRT4 was found to suppress the anti-neuroinflammatory activity of Tregs infiltrating the spinal cord following injury; when SIRT4 expression was genetically suppressed, Tregs made more anti-inflammatory factors, IL-10, FoxP3, and transforming growth factor beta (TGFβ). Thus, understanding how the SIRT4-Treg pathway can be manipulated could provide useful avenues to control both pathogenic and neuroprotective immune responses.