A modified mallory-cason staining procedure for large cryosections

Anterior longitudinal ligament in diffuse idiopathic skeletal hyperostosis: Ossified or displaced?

Diffuse idiopathic skeletal hyperostosis (DISH) is often theorized to be an ossification of the anterior longitudinal ligament (ALL). Using computed tomography (CT) imaging and cryomacrotome sectioning, we investigated the spatial relationship between the ALL and newly formed bone in DISH to test this hypothesis. In the current study, four human cadaveric spines diagnosed with DISH using CT imaging were frozen and sectioned using a cryomacrotome. Photographs were obtained of the specimen at 125 µm intervals. Manual segmentations of the ALL on cryomacrotome photographs were projected onto the three-dimensional reconstructed CT scans. The presence and location of newly formed bone were assessed in relationship to the location of the ALL. The ALL could be identified and segmented on the photographs at all levels. The ALL was located at the midline at levels where no new bone had formed. At the locations where new bone had abundantly formed, the ALL was displaced towards to the contralateral side and not replaced by bony tissue. The displacement of the-morphologically normal appearing-ALL away from the newly formed bone implies that newly formed bone in DISH may not originate from the ALL. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society J Orthop Res 36:2491-2496, 2018.

EUS-guided celiac ganglia neurolysis: a clinical and human cadaver study (with video)

BACKGROUND AND AIMS

There is little evidence that structures targeted during EUS-guided celiac ganglia neurolysis (EUS-CGN) are celiac ganglia and that selective ethanol injection into ganglia is feasible. We aimed to visualize celiac ganglia, confirm that these structures are ganglia, and visualize ethanol spread after EUS-CGN and EUS-guided celiac plexus neurolysis (EUS-CPN).

METHODS

First, celiac ganglia were sought during 97 consecutive EUS procedures. Second, ganglia were identified in a prosected human cadaver by placing a linear echoendoscope next to the celiac trunk and removing the underlying tissue for histology. Finally, various EUS-CGN and EUS-CPN techniques were performed in human cadavers; EUS-CGN was performed with 1 mL ethanol in 1 ganglion, 1 mL per ganglion (both low volume), and 4 mL per ganglion (high volume). EUS-CPN was performed with a central (20 mL) and a bilateral (2*10 mL) approach. Transverse sections (75 μm) were obtained and photographed to allow visualization of the spread of ethanol.

RESULTS

A total of 204 ganglia were detected in 83 patients. Mean (± standard deviation) size of the long axis was 8.1 mm (± 7.4 mm). Histology of the removed region in the cadaver showed only nerve cell bodies. After low-volume EUS-CGN in cadavers, ethanol spread well beyond the targeted ganglion. After high-volume EUS-CGN in cadavers, a larger ethanol spread was seen, which also reached unidentified ganglia; the spread was comparable to the spread after EUS-CPN.

CONCLUSIONS

Specific EUS-CGN is not feasible because ethanol spreads well beyond the targeted ganglion. Unidentified celiac ganglia are better reached with high-volume EUS-CGN, and this would likely result in a more thorough neurolysis. High-volume EUS-CGN should be preferred to low-volume EUS-CGN.

Different Approaches to Ultrasound-guided Thoracic Paravertebral Block: An Illustrated Review

Given the fast development and increasing clinical relevance of ultrasound guidance for thoracic paravertebral blockade, this review article strives (1) to provide comprehensive information on thoracic paravertebral space anatomy, tailored to the needs of a regional anesthesia practitioner, (2) to interpret ultrasound images of the thoracic paravertebral space using cross-sectional anatomical images that are matched in location and plane, and (3) to briefly describe and discuss different ultrasound-guided approaches to thoracic paravertebral blockade. To illustrate the pertinent anatomy, high-resolution photographs of anatomical cross-sections are used. By using voxel anatomy, it is possible to visualize the needle pathway of different approaches in the same human specimen. This offers a unique presentation of this complex anatomical region and is inherently more realistic than anatomical drawings.

Improved depiction of pterygopalatine fossa anatomy using ultrahigh-resolution magnetic resonance imaging at 7 tesla

Purpose. To study the anatomy of the pterygopalatine fossa (PPF) using ultrahigh-resolution magnetic resonance imaging. Methods. A human cadaveric tissue block containing the pterygopalatine fossa was examined on a clinical 7-Tesla magnetic resonance imaging system. Subsequently, cryosections of the tissue block were created in a coronal plane. The cryosections were photographed and collected on adhesive tape. The on-tape sections were stained for Mallory-Cason, in order to detail the anatomic structures within the fossa. Magnetic resonance images were compared with surface photos of the tissue block and on-tape sections. Results. High-resolution magnetic resonance images demonstrated the common macroscopic structures in the PPF. Smaller structures, best viewed at the level of the operation microscope, which have previously been obscured on magnetic resonance imaging, could be depicted. Some of the orbital pterygopalatine ganglion branches and the pharyngeal nerve were clearly viewed. Conclusions. In our experience with one human cadaver specimen, magnetic resonance imaging at 7 Tesla seems effective in depicting pterygopalatine fossa anatomy and provides previously unseen details through its demonstration of the pharyngeal nerve and the orbital pterygopalatine ganglion branches. The true viability of depicting the pterygopalatine fossa with ultrahigh-resolution MR will depend on confirmation of our results in larger studies.

Colocalization of ANCA-antigens and fibrinoid necrosis in ANCA-associated vasculitis

A variety of antineutrophil cytoplasmic auto-antibodies (ANCAs) are known to be associated with small vessel vasculitides such as Wegener's granulomatosis and microscopic polyangiitis. To visualize colocalization patterns of the fibrinoid necrotic lesions and ANCA-antigens more accurately, we have developed a double staining technique in which an immunohistochemical staining is followed by a histological staining. Instead of using sequential biopsy slides of histologically and immunohistochemically stained sections, which may lead to an underestimation of the number and size of the lesions, our technique permits the visualization of the colocalized patterns of fibrinoid necrosis with an ANCA-antigen in a single slide. The double staining procedure is presented in this Technical Note.

The lateral sellar nerve plexus and its connections in humans

OBJECT

The aim of the present study was to elucidate the systematic topography of the lateral sellar (cavernous sinus [CS]) nerve plexus and its connections in humans.

METHODS

Seven specimens of human CS and adjacent regions were dissected in steps and stained as whole-mount preparations by using a sensitive acetylcholinesterase method. Another specimen was frozen, cut on a frontal plane, and stained for acetylcholinesterase. The human CS contains an extensive nerve plexus with small ganglia. The plexus is composed of a main part, the lateral sellar plexus proper, which is located around the abducent nerve and medial to the ophthalmic nerve, and a lateral extension just underneath the outermost layer of the lateral CS wall, which is located lateral to the trochlear and ophthalmic nerves. The lateral sellar plexus is connected to the internal carotid nerve, the pterygopalatine ganglion, and the trigeminal ganglion. From the lateral sellar plexus, nerve branches run along the oculomotor, trochlear, ophthalmic, and abducent nerves into the orbit. In addition, the lateral sellar plexus has multiple connections with nerves located around the internal carotid artery. The presence of connections between the lateral sellar plexus and functionally defined neural structures suggests that the plexus receives sympathetic, parasympathetic, and sensory contributions.

CONCLUSIONS

The plexus may distribute nerve subpopulations to several targets, including cerebral arteries and orbital structures. The presence of a mixed nerve plexus that projects to a variety of targets indicates that injury or disease in the CS may result in a variety of symptoms.

A functional anatomic study of the relationship of the nasal cartilages and muscles to the nasal valve area

The functioning of the nasal valve area is largely determined by the stability and the mobility of the lateral nasal wall. To gain insight into the kinematics of the lateral nasal wall, we studied the functional anatomy of the nasal muscles and the intercartilaginous and osseous-cartilaginous junctions. We performed gross and microscopic nasal dissection and serial sectioning in 15 human cadaveric noses. In addition, two noses were used for three-dimensional reconstruction of the nasal cartilages. We conclude that the lateral nasal wall can be seen as made up of three parts. At the level of the osseous-cartilaginous chain of bone, lateral nasal cartilage, and lateral crus, the lateral nasal wall is relatively stable, limited mobility being allowed by translation and rotation in the intercartilaginous joint and a coupled distortion of the cartilages. At the level of the hinge area the lateral nasal wall is supported by one or more accessory cartilages, embedded in soft tissue, and therefore much more compliant. The alar part of the nasalis muscle, which originates from the maxilla and inserts on these cartilages, may dilate the valve area by drawing this hinge area laterally. The third and most compliant part of the lateral nasal wall is the part that is not supported by cartilage, the ala. The dilatator naris muscle largely occupies the ala and is attached to the lateral crus; it opens the vestibule and nostril. The third nasal muscle that influences the lateral nasal wall is the transverse part of the nasalis muscle. It overlies the nose but is not attached to it. This muscle stabilizes the lateral nasal wall, in particular, the lateral nasal cartilage, the intercartilaginous junction, and the hinge area, by moving the nasal skin.

Localizing role of hemodynamics in atherosclerosis in several human vertebrobasilar junction geometries

Atherosclerosis is a common finding in the vertebrobasilar junction and in the basilar artery. Several theories try to link the process of atherogenesis with the forces exerted by the flowing blood. An attractive relation has been found between the locations in vessels at which atherosclerotic plaques are often present and the locations in models where complicated flow patterns exist. Most of the studies provided data on bifurcations. Finding a similar relation in an arterial confluence would certainly add to the credibility of the (causal) relationship between hemodynamics and atherosclerosis. Further support can be provided if variations of the geometry result in changes of the location of the atherosclerotic lesions, corresponding to the changes of the flow force distribution. In our previous numerical and experimental work, the influence of geometric and hemodynamic parameters, such as asymmetrical inflow, confluence angle, and blunting of the apex, on the flow in vertebrobasilar junction models has been investigated in detail. Recirculation areas and distribution of the wall shear stress have been computed. In this anatomic study, the effect of modulation of these geometric and hemodynamic parameters on the flow pattern is compared with the size and location of plaques in human vertebrobasilar junctions and basilar arteries. In addition, a comparison is made between the preferential areas of atherosclerotic plaques in junctions and bifurcations to demonstrate the localizing role of hemodynamics in atherogenesis. The apex of the vertebrobasilar junction and the lateral walls of the basilar artery appeared to be prone to atherosclerosis. In 43 of 85 vertebrobasilar junctions, a plaque was found at the apex. Furthermore, the summed plaque thickness at both lateral walls differs significantly (paired t test, P=.03) from that at the walls facing the pons and the skull base. In contrast, several authors found that the lateral walls of the mother vessel and the apex in bifurcations are often spared. Modulation of the various parameters in the models changed the size of the regions with low wall shear stress and/or recirculation areas dramatically. A comparable effect was found in the occurrence of plaques in the human vertebrobasilar junction; eg, for an atherosclerotic plaque at the apex, a predicted probability larger than 0.5 was computed for blunted apexes and for sharp-edged apexes with a confluence angle exceeding 90 degrees. Apparently, two geometric risk factors for an atherosclerotic plaque at the apex can be distinguished: a blunted apex and a large confluence angle.

Electrode positioning in thoracic percutaneous partial rhizotomy: an anatomical study

The present study was undertaken to clarify if needle positioning in percutaneous partial rhizotomy in the thoracic area based on bony landmarks and guided by fluoroscopic control leads to adequate placement in or at the targeted nervous tissue, i.e., the dorsal root ganglion (DRG), and to determine if needle localization by CT is more reliable than by fluoroscopic control. An investigation was performed in 2 cadavers, simulating the clinical setting as much as possible. At the levels T1-T8 a drill hole was made in the vertebral arc with a Kirschner wire. At the levels T9-T12 the "classic" dorsolateral technique was used. In 46 procedures the position of the needle tips was compared using hard copies of the fluoroscopic images, CT images at 1.5 mm intervals, surface photographs, and stained 25 microns sections obtained by a multirange heavy duty cryomicrotome. The position of the DRG in the foramen, and its size, were measured. In the sections, considered as the "golden standard", in 28 cases (60.9%) the needle tip was found in the DRG and in the extradural dorsal root in 14 cases (30.4%). In 4 cases (8.7%) no nervous tissue was encountered. In 8 of 32 "drill hole procedures" the facet joint was pierced. No accidental pleural puncture occurred in any of the procedures. The needle position was imaged more accurately by fluoroscopy. It is concluded that fluoroscopic control is a reliable guide to needle placement in percutaneous partial rhizotomy and permits standardization of the technique with the help of bony landmarks.

Parameters in electrode positioning in thoracic percutaneous facet denervation: an anatomical study

The purpose of the present study was to verify if needle placement in thoracic percutaneous facet denervation (PFD), based on bony landmarks, and under fluoroscopic guidance, would lead to constant anatomical positioning; and hence to an adequate placement at the assumed target, i.e., the medial branch of the dorsal ramus of the spinal nerve; and furthermore to determine if interpretation of the needle position by CT is more reliable than by fluoroscopy. The procedures were carried out bilaterally at all 12 levels on two cadavers, simulating the clinical setting as much as possible. In 44 cases the position of the needles was determined on hard copies of fluoroscopic images, 1.5 mm interval CT-images, surface-photographs, and on counterstained 25 microns sections obtained by a multirange heavy duty cryomicrotome. The sections established that standardized use of bony landmarks under fluoroscopic control can result in reproducible anatomical needle positioning in thoracic PFD. Nervous tissue was hit in 27 (61%) cases, but the supposed target structure, i.e., the medial branch "stem" was never hit. In none of the procedures was an accidental pleural puncture observed. The correlation between fluoroscopic images and sections was poor. The correlation between CT and sections was better, except for the mediolateral direction. The results of the present study suggest that "pure" anatomical positioning based on bony landmarks analogous to those used in the lumbar region is not reliable enough for thoracic PFD, and that corrections after electrostimulation substantially contribute to obtaining an adequate position of the needle.

Location of implants in the interforaminal region of the mandible and the consequences for the design of the superstructure

The location and the number of implants to support an overdenture is of major importance for the superstructure design. Sometimes, jaw bone anatomy or posteriorly placed implants enforce the use of an angular bar to achieve a position above the alveolar ridge. Loads on such a bar may introduce a moment on the implants which can result in high bone stresses and eventually the loss of the implants. This study on stress distribution in the bone around the implants in an edentulous mandible was performed using a three-dimensional finite element model. One model with two implants placed just anteriorly of the mental foramen and connected with an anteriorly placed bar, following the curvature of the alveolar ridge, was compared with two other designs. First with a similar model but now without a bar and secondly with a model with four implants connected with straight bars. It is concluded that loading a bar, which is placed anteriorly of the interconnecting line between two implants, causes extremely large compressive and tensile stress concentrations in the bone around the implants. Therefore, in those cases, it is advised not to connect the implants or, in case a bar-clip attachment is preferred, to place additional implants in the frontal region.

A three-dimensional, finite-element analysis of bone around dental implants in an edentulous human mandible

The design of dental superstructures influences the loading on dental implants and the deformation of the anterior interforaminal bone in an edentulous mandible. This deformation causes stress in the bone around the implants and may lead to bone resorption and loss of the implant. The stress distribution around dental implants in an edentulous mandible was calculated by means of a three-dimensional, finite-element model of an entire lower jaw. This model was built from data obtained from slices of a single human mandible and was provided with two endosseous implants in the interforaminal region. The implants were either connected with a bar or remained solitary, and were loaded with a horizontal bite force of 10 N, a vertical bite force of 35 N, or an oblique bite force of 70 N. The most extreme principal stresses in the bone were always located around the neck of the implant. Stress around the implant was, therefore, not only caused by the local deformation of the bone due to movement of the implant and interface relative to the surrounding bone but also by the bending of the mandible. The most extreme principal stress was found with oblique bite forces. The highest maximum and lowest minimum principal stresses were 7.4 and -16.2 MPa in the model without the bar and 6.5 and -16.5 MPa in the model with the bar. When differences in the amount of bite force were eliminated, the vertical bite force resulted in the lowest stress.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of three finite element models of an edentulous mandible provided with implants

The stress distribution in an edentulous mandible provided with two implants in the interforaminal region was calculated by means of three different finite element models. The implants were connected with a bar or remained solitary. The first model was a three-dimensional representation of the entire mandible, the second model of the interforaminal region of this same mandible, whilst the third model was a two-dimensional representation of the interforaminal region. The differences in stress distribution around the connected implants and the solitary implants between these three models were analysed. It can be concluded that for a parameter study the stress distribution around the dental implants following from a three-dimensional finite element model of only the interforaminal region of an edentulous mandible can be used. For such studies therefore, benefit can be gained from the advantages of reduced modelling and calculation time.