Invasive Corridor of Clivus Extension in Pituitary Adenoma: Bony Anatomic Consideration, Surgical Outcome and Technical Nuances.

BACKGROUND: It is well known that the clivus is composed of abundant cancellous bone and is often invaded by pituitary adenoma (PA), but the range of these cancellous bone corridors is unknown. In addition, we found that PA with clivus invasion is sometimes accompanied by petrous apex invasion, so we speculated that the petrous apex tumor originated from the clivus cancellous bone corridor. The aim of this study was to test this hypothesis by investigating the bony anatomy associated with PA with clival invasion and its clinical significance. METHODS: Twenty-two cadaveric heads were used in the anatomical study to research the bony architecture of the clivus and petrous apex, including six injected specimens for microsurgical dissection and sixteen cadavers for epoxy sheet plastination. The surgical videos and outcomes of PA with clival invasion in our single center were also retrospectively reviewed. RESULTS: The hypoglossal canal and internal acoustic meatus are composed of bone canals surrounded by cortical bone. The cancellous corridor within clivus starts from the sellar or sphenoid sinus floor and extends downward, bypassing the hypoglossal canal and finally reaching the occipital condyle and the medial edge of the jugular foramen. Interestingly, we found that the cancellous bone of the clivus was connected with that of the petrous apex through petroclival fissure extending to the medial margin of the internal acoustic meatus instead of a separating cortical bone between them as it should be. It is satisfactory that the anatomical outcomes of the cancellous corridor and the path of PA with clival invasion observed intraoperatively are completely consistent. In the retrospective cohort of 49 PA patients, the clival component was completely resected in 44 (89.8%), and only five (10.2%) patients in the early-stage had partial residual cases in the inferior clivus. CONCLUSION: The petrous apex invasion of PA is caused by the tumor invading the clivus and crossing the petroclival fissure along the cancellous bone corridor. PA invade the clivus along the cancellous bone corridor and can also cross the hypoglossal canal to the occipital condyle. This clival invasion pattern presented here deepens our understanding of the invasive characteristics of PA.

Fine configuration of the dural fibrous network and the extradural neural axis compartment in the jugular foramen: an epoxy sheet plastination and confocal microscopy study.

OBJECTIVE: The extradural neural axis compartment (EDNAC) is an adipovenous zone that is located between the meningeal (ML) and endosteal (EL) layers of the dura mater and has been minimally investigated in the jugular foramen (JF) region. In this study, the authors aimed to explore the fine architecture of the EDNAC within the JF and evaluate whether the EDNAC can be used as a component for JF compartmentalization. METHODS: A total of 46 cadaveric heads (31 male, 15 female; age range 54-96 years) and 30 dry skulls were examined in this study. Twelve of 46 cadaveric heads were plastinated as a series of transverse (7 sets), coronal (3 sets), and sagittal (2 sets) slices and examined using stereomicroscopy and confocal microscopy. The dural entry points of the JF cranial nerves were recorded in 34 cadaveric skulls. The volumes of the JF, intraforaminal EDNAC, and internal jugular vein (IJV) were quantified. RESULTS: Based on constant osseous landmarks, the JF was subdivided into preforaminal, intraforaminal, and subforaminal segments. The ML-derived fascial sheath along the anteromedial wall of the IJV demarcated the "venous portion" and the "EDNAC portion" of the bipartite JF. The EDNAC did not surround the intraforaminal IJV and comprised an ML-derived dural fibrous network and an adipose matrix. A fibrovenous curtain subdivided the intraforaminal EDNAC into a small anterior column containing cranial nerve (CN) IX and the anterior condylar venous plexus and a large posterior adipose column containing CNs X and XI. In the intraforaminal segment, the IJV occupied a slightly larger space in the foramen (57%; p < 0.01), whereas in the subforaminal segment it occupied a space of similar size to that of the EDNAC. CONCLUSIONS: Excluding the IJV, the neurovascular structures in the JF traverse the dural fibrous network that is dominant in the foraminal EDNAC. The results of this study will contribute to anatomical knowledge of the obscure yet crucially important JF region, increase understanding of foraminal tumor growth and spread patterns, and facilitate the planning and execution of surgical interventions.

Three-dimensional architecture of the neurovascular and adipose zones of the upper and lower lumbar intervertebral foramina: an epoxy sheet plastination study.

OBJECTIVE: Kambin's triangle and the safe triangle are common posterolateral approaches for lumbar transforaminal endoscopic surgery and epidural injection. To date, no consensus has been reached on the optimal transforaminal approach, in particular its underlying anatomical mechanism. The aim of this study was to investigate the 3D architecture of the neurovascular and adipose zones in the upper and lower lumbar intervertebral foramina (IVFs). METHODS: Using the epoxy sheet plastination technology, 22 cadaveric lumbar spines (12 female and 10 male, age range 46-89 years) were prepared as a series of transverse (11 sets), sagittal (8 sets), and coronal (3 sets) slices with a thickness of 0.25 mm (6 sets) or 2.5 mm (16 sets). The high-resolution images of the slices were scanned and analyzed. The height, area, and volume of 30 IVFs from T12-L1 to L4-5 were estimated and compared. This study was performed in accord with the authors' institutional ethical guidelines and approved by the institutional ethics committees. RESULTS: The findings were as follows. 1) The 3D boundaries of the lumbar IVF and its subdivisions were precisely defined. 2) The 3D configuration of the neurovascular and adipose zones was different between the upper and lower lumbar IVFs; zoning in the upper lumbar IVFs was much more complex than that in the lower lumbar IVFs. 3) In general, the infraneural adipose zone gradually tapered and rotated from the inferoposterolateral aspect to the superoanteromedial aspect. 4) The average height, area, and volume of the IVF gradually increased from the upper to the lower lumbar spine. Within a lumbar IVF, the volumes below and above the inferior border of the dorsal root ganglia were similar. CONCLUSIONS: This study highlights differences of fine 3D architecture of neurovascular and adipose tissues between the upper and lower lumbar IVFs, with related effects on the transforaminal approaches. The findings may contribute to optimization of the surgical approaches to and through the IVF at different lumbar spinal levels and also may help to shorten the learning curve for the transforminal techniques.

Desarrollo de un protocolo de plastinación de cortes con resina poliéster aplicado a secciones de cerebro humano / Development of a sheet plastination protocol with polyester resin applied to human brain slices

La plastinación es una técnica anatómica de conservación cadavérica creada en 1977 por Gunther von Hagens, en Heidelberg, Alemania, y que sustituye los líquidos biológicos y/o de fijación por acetona, para luego impregar las muestras con distintas resinas, dependiendo de la técnica de plastinación desarrollada, para finalmente llevar a cabo la polimerización de los componentes incorporados a las muestras, para obtener muestras biológicas secas y totalmente duraderas. El objetivo de este trabajo consistió en desarrollar un protocolo de plastinación de cortes con resina poliéster (Biodur® P40) en secciones de 3 mm de espesor de cerebro humano. La muestras fueron fijadas y conservadas con formalina al 10 %. Los cerebros luego fueron seccionados con una maquina cortadora de tejidos, obteniéndose láminas delgadas de 3 mm de espesor. Inmediatamente los cortes de cerebro fueron colocados en deshidratación en acetona al 100 %, a -25 ºC, durante 7 días el primer baño de acetona, y durante otros 3 días más, para el segundo baño de acetona. Una vez deshidratados los cortes, estos fueron colocados en resina poliéster Biodur® P40 y se llevó a cabo la impregnación forzada de los cortes, en cámara de vacío a temperatura ambiente (20 ºC). Una vez finalizada la impregnación forzada, se procedió a la etapa de curado, la cual en primer lugar consiste en el armado de las cámaras de curado dentro de las cuales se colocaran los cortes con resina poliéster. Las cámaras de curado fueron colocadas bajo luz UV para acelerar la polimerización del poliéster y finalizar el proceso de plastinación. Se logró desarrollar satisfactoriamente en el Laboratorio de Plastinación y Técnicas Anatómicas de la Universidad de La Frontera un protocolo de plastinación de cortes con resina poliéster, obteniendo una excelente conservación de cortes de cerebro, con diferenciación de sustancias gris y blanca, y conservación de todas las características morfológicas.

Plastination is an anatomical technique of cadaveric conservation created in 1977 by Gunther von Hagens, in Heidelberg, Germany, and that substitutes biological and / or fixation fluids with acetone, to then impregnate the samples with different resins, depending on the developed plastination technique, to finally carry out the polymerization of the components incorporated into the samples, to obtain dry and totally durable biological samples. The aim of this work was to develop a sheet plastination protocol with polyester resin (Biodur® P40) in 3 mm thick slices of human brain. The samples were fixed and preserved with 10 % formalin. The brains were sectioned with a slice cut machine, obtaining thin sheets of 3 mm thick. Immediately the slices of brain were placed in dehydration in 100 % acetone, at -25 °C, for 7 days the first acetone bath, and for another 3 more days, for the second acetone bath. Once the cuts were dehydrated, they were placed in Biodur® P40 polyester resin and the forced impregnation was carried out in a vacuum chamber at room temperature (20 °C). Once the forced impregnation was finished, the curing stage was carried out, which first consists in the assembly of the curing chambers within which the slices with polyester resin were placed. The curing chambers were placed under UV light to accelerate the polymerization of the polyester and finished the plastination process. A sheet plastination protocol with polyester resin was successfully developed in the Laboratory of Plastination and Anatomical Techniques of Universidad de La Frontera, obtaining excellent conservation of brain slices, with differentiation of gray and white substances, and conservation of all morphological characteristics.

P40 polyester sheet plastination technique for brain and body slices: The vertical and horizontal flat chamber methods.

The P40 technique produces high-quality brain and body slices and is the user-friendliest of the polyester techniques. The P40 polyester technique follows the same classical steps for plastination. That is, preparation of the specimen, fixation (optional), dehydration by freeze substitution, forced impregnation and curing. Two methods used to prepare two different types of specimens, that is, brain slices and body slices are described. Each method has its own characteristics depending on the specimen type used. Brain slices were used to illustrate the vertical small chamber method while the body slices were used to illustrate the horizontal large chamber method. The brain slices obtained using P40 are of very good quality presenting good contrast between grey and white matter. The body slices are also of very good quality. The physical appearance of these slices makes them an exceptional instrument for diagnostic imaging and anatomical correlation. Body slices prepared with P40 retain the natural colour of the tissue and preserve the anatomical relationships.

Fine architecture of the fascial planes around the lateral femoral cutaneous nerve at its pelvic exit: an epoxy sheet plastination and confocal microscopy study.

OBJECTIVE: Meralgia paresthetica is commonly caused by mechanical entrapment of the lateral femoral cutaneous nerve (LFCN). The entrapment often occurs at the site where the nerve exits the pelvis. Its optimal surgical management remains to be established, partly because the fine architecture of the fascial planes around the LFCN has not been elucidated. The aim of this study was to define the fascial configuration around the LFCN at its pelvic exit. METHODS: Thirty-six cadavers (18 female, 18 male; age range 38-97 years) were used for dissection (57 sides of 30 cadavers) and sheet plastination and confocal microscopy (2 transverse and 4 sagittal sets of slices from 6 cadavers). Thirty-four healthy volunteers (19 female, 15 male; age range 20-62 years) were examined with ultrasonography. RESULTS: The LFCN exited the pelvis via a tendinous canal within the internal oblique-iliac fascia septum and then ran in an adipose compartment between the sartorius and iliolata ligaments inferior to the anterior superior iliac spine (ASIS). The iliolata ligaments newly defined and termed in this study were 2-3 curtain strip-like structures which attached to the ASIS superiorly, were interwoven with the fascia lata inferomedially, and continued laterally as skin ligaments anchoring to the skin. Between the sartorius and tensor fasciae latae, the LFCN ran in a longitudinal ligamental canal bordered by the iliolata ligaments. CONCLUSIONS: This study demonstrated that 1) the pelvic exit of the LFCN is within the internal oblique aponeurosis and 2) the iliolata ligaments form the part of the fascia lata over the LFCN and upper sartorius. These results indicate that the internal oblique-iliac fascia septum and iliolata ligaments may make the LFCN susceptible to mechanical entrapment near the ASIS. To surgically decompress the LFCN, it may be necessary to incise the oblique aponeurosis and iliac fascia medial to the LFCN tendinous canal and to free the iliolata ligaments from the ASIS.

Epoxy sheet plastination on a rabbit head - new faster protocol with Biodur® E12/E1 / Plastinación de cortes con resina epoxi en una cabeza de conejo - nuevo protocolo rápido con Biodur® E12/E1

SUMMARY: Plastination is an anatomical technique of cadaveric preservation that allows the preservation of anatomical pieces indefinitely, in dry and odorless form. It was created in 1978 by Gunther von Hagens, in Heidelberg, Germany. In particular, the sheet plastination technique, with epoxy resin, allows the generation of thin sections of various anatomical regions, allowing an accurate visualization of anatomical structures of difficult access through dissection or cadaveric exploration. The aim of this work was to present a new sheet plastination protocol with Biodur® E12/E1, which is faster in its implementation, applied, for the first time, in a rabbit head.

RESUMEN: La plastinación es una técnica anatómica de preservación cadavérica que permite la conservación de piezas anatómicas indefinidamente, en forma seca e inodora. Fue creada en 1978 por Gunther von Hagens, en Heidelberg, Alemania. En particular, la técnica de plastinación de cortes, con resina epoxi, permite la generación de secciones delgadas de diversas regiones anatómicas, asegurando una visualización precisa de estructuras anatómicas de difícil acceso mediante disección o exploración de cadáveres. El objetivo de este trabajo fue presentar un nuevo protocolo de plastinación de cortes con resina Biodur® E12/E1, más rápido en su implementación, aplicada por primera vez, en una cabeza de conejo.

Visualisation of facet joint recesses of the cadaveric spine: a micro-CT and sheet plastination study.

OBJECTIVES: The size and shape of a joint cavity are the key determinates for the mobility of the joint. The anatomy and configuration of the facet joint (FJ) recesses at different levels of the spine remain unclear and controversial. The aim of this study was to identify the configuration of the FJ recesses in the cervical, thoracic and lumbar spine using a combination of micro-CT and sheet plastination techniques. METHODS: Of 19 cadavers (9 males, 10 females, age range of 54-89 years), the FJ cavities of 3 spines were injected with contrast filling and scanned with micro-CT, and 16 plastinated spines were prepared as the series of sagittal (9 sets), transverse (5 sets) or coronal (2 sets) sections with a thickness of 2.5 mm and examined under a stereoscopic microscope. RESULTS: This study characterised the FJ spaces and recesses of the spine and found that (1) the configuration and extent of the FJ recesses varied along the spine. The optimal needle approach to the FJ cavity was via an anterolateral or posterolateral recess at the cervical level, along the tip of the inferior articular process at the thoracic level and via the posteromedial recess at the lumbar level. (2) The FJ cavity did not communicate with the retrodural space. CONCLUSION: The anatomical features of the FJ recesses at different levels of the spine confirm no direct communication between the FJ cavity and retrodural space.

Report on a sheet plastination technique using commercial epoxy resin / Reporte sobre una técnica de plastinación de cortes usando una resina epoxy comercial

Plastination is a conservation technique which allows anatomical pieces to be preserved, dry and odor-free, for an indefinite period. In particular, plastination of sections of tissue with epoxy resin allows very thin slices to be made of various regions of the anatomy, permitting close viewing of anatomical structures which are difficult to access by dissection or cadaver exploration. The objective of this work is to present a plastination technique developed in our laboratory for tissue sections using commercial epoxy resin, as an alternative to the existing classic plastination techniques. The technique was applied to a human knee, obtaining 5 mm thick sections which were compared with computerized tomography images. The development of an alternative sheet plastination technique using epoxy resin allows the preservation of anatomical regions which are difficult to study, with the possibility of comparing the sections with imaging studies. In this way anatomy can be usefully combined with clinical experience, allowing students to gain more significant knowledge of anatomy. The technique would also ensure provision of anatomical samples for research in the area of morphological science.

La plastinación es una técnica anatómica de conservación cadavérica que permite la preservación por tiempo indeterminado, en forma seca y sin olor, de piezas anatómicas. En particular, la técnica de plastinación por cortes, con resina epoxy, permite a su vez la generación de cortes delgados de diversas regiones anatómicas, permitiendo una visualización precisa de estructuras anatómicas de difícil acceso a través de la disección o la exploración cadavérica. El objetivo de este trabajo es el de presentar el desarrollo por parte de nuestro laboratorio de una técnica de plastinación de cortes con resina epoxy comercial, alternativa a las técnicas clásicas de plastinación de cortes existentes. Se aplicó la técnica en una rodilla humana, obteniéndose cortes de 5 mm de espesor, los cuales fueron comparados con imágenes de tomografía computada. El desarrollo de una técnica alternativa de plastinación de cortes con resina epoxy permitirá la conservación de regiones anatómicas de difícil estudio, con posibilidad de realizar la comparación de cortes con estudios imagenológicos, para combinar en forma adecuada la anatomía con la experiencia clínica y, de esta manera, permitir que el alumno alcance un aprendizaje más significativo de la anatomía, además de asegurar la obtención de muestras anatómicas para el desarrollo de investigación en el área de las ciencias morfológicas.

Histochemical staining techniques applied in ultrathin sheet plastination slice / 解剖学报

Objective To investigate whether and what staining techniques are applied to the ultrathin sheet plastination slice and whether the stained specimen is of autofluorescences .Methods A cadaveric hand block was plastinated and then sectioned as a series of 300-400μm thick transverse sections .A total of 56 slices in total .Alternative sections were stained with hematoxylin -eosin staining ( HE) , Verhoeff -Van Gieson staining ( VVG) or methylene blue and azureⅡstaining(MA).The stained slices were examined under a light microscope and a confocal microscope .Results The plastinated slices were stained with the three staining methods .HE staining revealed the muscle and connective tissues were red or violet , bone was violet or blue;VVG staining showed the elastic fibers was black , the collagen was red , and other tissues were yellow .MA staining showed the tendon was violet , the bone was pink , cartilage was violet , and other tissues were purple.However, the intracellular structures appeared not very well stained .The collagen, elastin and muscular structures in the stained slices were observed under a confocal microscope .Conclusion The commonly used histology staining methods can be used to stain the ultrathin sheet plastination slices .The staining provides a better observation of various tissues in the slice than the unstained slice .After staining, those autofluorescent structures in the plastinated slice are detectable under a confocal microscope .

Microcomputed tomography visualization of the cricoarytenoid joint cavity in cadavers.

OBJECTIVES: To visualize the cricoarytenoid joint (CAJ) cavity of the human cadaver and to correlate its appearance to the CAJ capsule. STUDY DESIGN: Prospective. METHODS: A total of 26 cadavers were used for microcomputed tomography arthrography, histology, and epoxy sheet plastination examinations. RESULTS: (1) The dimension of the CAJ cavity was much larger than the articular surfaces; (2) The posterior capsule of the CAJ was significantly strengthened, contained rich elastin fibers, and shared a common attachment with the posterior cricoarytenoid muscle; (3) The arytenoid cartilage was distanced from the cricoid cartilage at the superomedial aspect of the CAJ. CONCLUSIONS: This study demonstrates that the posterior fibrous capsule is the primary passive stabilizer of the CAJ and suggests that in addition to the gliding, rucking, and rotation, a visor-like jumping of the arytenoid cartilage on the cricoid cartilage may provide further adjustments in motions of the vocal fold. The finding of this study has implications for the biomechanics of the CAJ motion; the differential diagnosis of CAJ disorders, such as CAJ dislocation and subluxation; and surgical correction of the CAJ dysfunction.