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When describing and illustrating vertebrae, it is important to consistently depict their orientation, so we can objectively assess and compare the slope of the neural arch, neural canal, or articular surfaces. However, differing vertebral shapes across taxa and across regions of the spinal column make it difficult to maintain consistency, or even define what we mean by the directions “cranial” and “caudal”. Consequently, characters such as “Neural arch slopes cranially 30° relative to the vertical” are disputable rather than objective measurements. Cranial and caudal are defined as directed along the horizontal axis, but several different definitions of “horizontal” are possible:1. Long axis of centrum is horizontal. This is appealing for elongate vertebrae such as sauropod cervicals, but is not always well defined, and is difficult to determine for craniocaudally short vertebrae such as most caudals.2. Articular surfaces of centrum are vertical. Difficult to determine when dealing with facets that are concave or (worse) convex; and ambiguous for “keystoned” vertebrae in which the facets are not parallel.3. Neural canal is horizontal. Anatomically informative, but difficult to determine in vertebrae that have not been fully prepared or CT-scanned, and impossible to see in lateral view. Ambiguous for vertebrae where the dorsal and ventral margins of the canal are not straight or not parallel.4. Similarity in articulation (“horizontal” is defined as a line joining the same point on two similarly oriented copies of the same vertebra when optimally articulated). This is less intuitive than definitions 1–3, but takes the entire vertebra into account.We advocate explicitly stating a definition and using it consistently. In most cases, definition 3 (“Neural canal is horizontal”) best reflects anatomical and developmental realities, and it is therefore preferred. Low-tech methods can be used to determine neural canal orientation with adequate precision for most purposes.

Purpose To measure the magnitude and direction of anterior scleral canal opening (ASCO) offset relative to the Bruch membrane opening (BMO) (ASCO/BMO offset) to characterize neural canal obliqueness and minimum cross-sectional area (NCMCA) in 69 highly myopic and 138 healthy, age-matched, control eyes. Design Cross-sectional study. Methods Using optical coherence tomography (OCT) scans of the optic nerve head (ONH), BMO and ASCO were manually segmented and their centroids and size and shape were calculated. ASCO/BMO offset magnitude and direction were measured after projecting the ASCO/BMO centroid vector onto the BMO plane. Neural canal axis obliqueness was defined as the angle between the ASCO/BMO centroid vector and the vector perpendicular to the BMO plane. NCMCA was defined by projecting BMO and ASCO points onto a plane perpendicular to the neural canal axis and measuring their overlapping area. Results ASCO/BMO offset magnitude was greater (highly myopic eyes 264.3 ± 131.1 μm; healthy control subjects 89.0 ± 55.8 μm, P Conclusions Our data suggest that increased temporal displacement of BMO relative to the ASCO, increased BMO and ASCO area, decreased NCMCA, and increased neural canal obliqueness are characteristic components of ONH morphology in highly myopic eyes.

The neural tissue engineering has been designed as a subset of tissue engineering for treating congenital malformations and accident injuries, particularly for individuals requiring tissue grafting. Such transplants, usually performed as autografting, can often not meet the requirements of an effective scaffold used in nerve tissue engineering. A novel neural tissue scaffold was introduced here to solve the problem concerning the reduced graphene oxide. The three-dimensional graphene oxide in the neural canal restricts the formation of fibroglandular tissues and facilities neural stem cell proliferation and growth. In these techniques, graphene oxide aerogel was initially made. Then, the freeze-drying process was used to fix the geometry of reduced graphene oxide hydrogels prepared using graphene oxide dispersion and ethylenediamine and gain aerogels. The X-ray diffraction patterns, FTIR and morphological related to samples were examined, followed by conducting in-vitro micropropagation and 4, 6-diamidino-2-phenylindol (DAPI) staining in fibroblast and P19 cultures. The results from immunofluorescence staining demonstrated the neural differentiation of P19 cells. It can be concluded that most cells attached to and differentiated on the scaffold surface and axons can penetrate randomly through them. Finally, the three-dimensional graphene oxide was proposed as an ideal alternative to be used in neural tissue engineering.

PurposeInvestigate the effects of myopia and glaucoma in the prelaminar neural canal and anterior lamina cribrosa using 1060-nm swept-source optical coherence tomographyDesignRetrospective, cross-sectional studyMethodsSettingClinical practicePatient or study population19 controls (38 eyes); 38 glaucomatous subjects (63 eyes). Inclusion criteria for glaucomatous subjects: i) optic disc neural rim loss; ii) peripapillary nerve fibre layer (NFL) loss on spectral domain optical coherence tomography (SD-OCT); iii) glaucomatous visual field defect with an abnormal pattern standard deviation (PIntervention or observation proceduresSwept-source optical coherence tomographyMain Outcome Measure(s)Bruchs membrane opening (BMO) and anterior laminar insertion (ALI) dimension, prelaminar neural canal dimension, anterior lamina cribrosa surface (ALCS) depthResultsGlaucomatous eyes had more bowed and nasally rotated BMO and ALI, more horizontally skewed prelaminar neural canal, and deeper ALCS than the control eyes. Increased axial length was associated with a wider, longer, and more horizontally skewed neural canal, and decrease in the ALCS depth and curvature.ConclusionOur findings suggest that glaucomatous posterior bowing or cupping of lamina cribrosa can be significantly confounded by the myopic expansion of the neural canal. This may be related to higher glaucoma risk associated with myopia from decreased compliance and increased susceptibility to IOP-related damage of LC being pulled taut.

BACKGROUND: The mandibular incisive canal (MIC) is a neural canal containing one of the lower branches of the inferior alveolar nerve, called the mandibular incisive nerve, which can get damaged and cause complications during the removal of bone from the interforaminal region. OBJECTIVES: The aim of this study was to determine the effect of the inversion filter (IF) on improving the visibility of MIC as compared to the original images. MATERIAL AND METHODS: In this retrospective, descriptive, analytical study, 343 samples of digital panoramic radiography were examined. The images were analyzed with and without IF. The frequency and confidence intervals (CIs) of identifying MIC were used to determine its visibility, both with IF and in the original images. Besides, the difference between the maximum and minimum diameters of the canal as well as the distance from MIC to the alveolar crest and to the mental foramen were examined. For statistical analysis, McNemar's test and the paired t-test were used, and the concordance was calculated using the kappa coefficient. RESULTS: No significant differences were found in the prevalence of the incisive canal, or in its unilateral or bilateral visibility between the original and filtered radiography in this study (p = 0.42 and p = 0.67, respectively). The absolute values of the interval difference between MIC and the mental foramen, the maximum and minimum diameters of MIC, and the distance from MIC to the alveolar crest were statistically significant between the filtered and original radiography, although the difference was clinically unimportant. CONCLUSIONS: The use of IF produced results similar to the original radiography; its application neither increased the clarity nor improved the visibility of the incisive canal.

Reissner’s fiber (RF) is a secreted filament that floats in the neural canal of chordates. Since its discovery in 1860, there has been no agreement on its primary function, and its strong conservation across chordate species has remained a mystery for comparative neuroanatomists. Several findings, including the chemical composition and the phylogenetic history of RF, clinical observations associating RF with the development of the neural canal, and more recent studies suggesting that RF is needed to develop a straight vertebral column, may shed light on the functions of this structure across chordates. In this article, we will briefly review the evidence mentioned above to suggest a role of RF in the origin of fundamental innovations of the chordate body plan, especially the elongation of the neural tube and maintenance of the body axis. We will also mention the relevance of RF for medical conditions like hydrocephalus, scoliosis of the vertebral spine and possibly regeneration of the spinal cord.

The vertebrae of sauropod dinosaurs have distinctive and complex pneumatic features including fossae and foramina in the sides of their centra. These vary between individuals, serially within individuals, and even between the left and right sides of single vertebrae. This presents a conundrum because bone is usually the least variable material in the vertebrate body. Blood vessels, however, are much more labile, as can be seen in the varied occurrence of vascular foramina in the vertebrae not only of sauropods, but also of birds, crocodilians and mammals. Vascular variation arises in part from the ontogeny of vertebrae, which in their embryonic state are vascularised from within the neural canal: the hand-off from these vessels to others which penetrate from outside is not always completed. In birds, pneumatizing diverticula enter the vertebrae alongside blood vessels, in the vascular foramina that they form, before excavating the surrounding bone into larger pneumatic foramina. We propose that the same was true in sauropods, and that variation of vascularization directly caused variation of pneumatization. In most vertebrae, a single vascular foramen carries both artery and vein, but occasionally these vessels separate and each forms a separate foramen. This explains why in rare cases individual sauropod vertebrae have two pneumatic cavities on a single side: each arises from the vascular foramen formed by either artery or vein.

Summary: Azhdarchid pterosaurs, the largest flying vertebrates, remain poorly understood, with fundamental aspects of their palaeobiology unknown. X-ray computed tomography reveals a complex internal micro-architecture for three-dimensionally preserved, hyper-elongate cervical vertebrae of the Cretaceous azhdarchid pterosaur, Alanqa sp. Incorporation of the neural canal within the body of the vertebra and elongation of the centrum result in a “tube within a tube” supported by helically distributed trabeculae. Linear elastic static analysis and linearized buckling analysis, accompanied with a finite element model, reveal that as few as 50 trabeculae increase the buckling load by up to 90%, implying that a vertebra without the trabeculae is more prone to elastic instability due to axial loads. Subsuming the neural tube into the centrum tube adds considerable stiffness to the cervical series, permitting the uptake of heavy prey items without risking damage to the cervical series, while at the same time allowing considerable skeletal mass reduction.

The sauropterygian clade Plesiosauria arose in the Late Triassic and survived to the very end of the Cretaceous. A long, flexible neck with over 35 cervicals (the highest number of cervicals in any tetrapod clade) is a synapomorphy of Pistosauroidea, the clade that contains Plesiosauria. Basal plesiosaurians retain this very long neck but greatly reduce neck flexibility. In addition, plesiosaurian cervicals have large, paired, and highly symmetrical foramina on the ventral side of the centrum, traditionally termed subcentral foramina, and on the floor of the neural canal. We found that these dorsal and the ventral foramina are connected by a canal that extends across the center of ossification of the vertebral centrum. We posit that these foramina are not for nutrient transfer to the vertebral centrum but that they are the osteological correlates of a highly paedomorphic vascular system in the neck of plesiosaurs. This is the retention of intersegmental arteries within the vertebral centrum that are usually obliterated during sclerotome re-segmentation in early embryonic development. The foramina and canals are a rare osteological correlate of the non-cranial vascular (arterial) system in fossil reptiles. The adaptive value of the retention of the intersegmental arteries may be improved oxygen transport during deep diving and thermoregulation. These features may have been important in the global dispersal of plesiosaurians.

Background: With the increasing longevity of population and a continually climbing proportion of middle-aged and elderly persons, the problem of lumbosacral spine is a significant health care issue, causing backache and Neurogenic claudication. Methods: Thirty patients with degenerative lumbar canal stenosis were included in study and wide interlaminar fenestration with or without discectomy was carried out. Patients were followed and analysis of the outcome was done for improvement in pain, neurological improvement and improvement in claudication distance. Results: Diagnosis of degenerative lumbar canal stenosis were made by clinical examination and confirmed by measuring neural canal diameter in MRI. Patients were selected randomly and total 30 patients included in study with mean age of 45.9 year and with mean duration of symptom was 38.67 months. Wide interlaminar fenestration was done at two level (L4-5, L5-S1) in 9 patients and at one level in remaining 21 patients (L4-L5 in 12 and L5-S1 in 9).All the patients improved in terms of back pain, sensory and motor symptoms including neurogenic claudication. Conclusion: At the end of our study we find that Wide Interlaminar fenestration done in degenerative lumbar canal stenosis provides not only full resolution of neurological symptom but also maintains spinal stability at the same time.

Bony ridges occur on the walls of the neural canal in caudal vertebrae of numerous sauropod dinosaurs. These neural canal ridges (NCRs) are anteroposteriorly elongated but do not extend to the ends of the canal. To date, we have observed NCRs in caudal vertebrae of Alamosaurus, Apatosaurus, Astrophocaudia,Brontomerus, Camarasaurus, and Diplodocus. Numerous similar structures occur in extant vertebrates: (1) Neurocentral joints are ventral to NCRs in sauropod caudal vertebrae, and NCRs occur in unfused juvenile arches. Hypothesis rejected. (2) Attachment scars from ligamentum flavum occur at the ends of the dorsal roof of the canal, not the midpoint of the lateral edges, and this mammalian ligament was probably absent in dinosaurs. Hypothesis rejected. (3) Smooth ridges separate the spinal cord from the dorsal spinal vein and paramedullary airways in some crocodilians and birds, respectively. However, these septa persist to the ends of the canal, giving it an 8-shape, unlike the discrete NCRs of dinosaurs. Hypothesis rejected. (4) Bony attachments for denticulate ligaments occur in some non-mammalian vertebrates. The dura mater around the spinal cord fuses to the periosteum of the neural canal in non-mammals, so the denticulate ligaments that support the spinal cord can leave ossified attachment scars. These spinal cord supports have been identified in teleosts, salamanders, and a juvenile lizard, and they are the best match for the morphology of the NCRs in sauropod vertebrae. Functions of NCRs remain obscure. Denticulate ligaments are largest in regions of the vertebral column that experience strong lateral flexion. The hypothesis that NCRs supported the spinal cord of sauropods during lateral tail-whipping is attractive, but inconsistent with our recent discovery of NCRs in a hadrosaur caudal. NCRs are a new osteological correlate of the peripheral nervous system in dinosaurs, and highlight the need for more study in this area.

Eight amniote genera (representing four clades) became aquatic during the Permian. The four clades were mesosaurids, tangasaurids, the neodiapsid Claudiosaurus, and the procolophonid Barasaurus. Two of eight genera survived the end-Permian mass extinction, but did not last long into the Mesozoic. A previously undescribed specimen of Claudiosaurus germaini, preserved in a lacustrine concretion from the Sakamena Formation, Madagascar, bears seventeen vertebrae that has been split along an approximate horizontal plane to reveal sections of neural canal casted in white calcite. Enlargement of the neural canal in the sacral region of this specimen of Claudiosaurus (vertebral segments 22-26) is more similar to that of Tupinambis (segments 24-28) than it is to Testudo (segments 16-23). Claudiosaurus skeletal anatomy provides evidence for swim propulsion by both hind limbs and by undulation of a dorsal-ventrally flattened tail. Evidence for the latter includes elongate transverse processes on distal tail vertebrae. Other Permian aquatic reptile genera (Mesosaurus, Hovasaurus, Barasaurus) used snake-like side-to-side tail undulation, whereas Claudiosaurus used cetacean-like up-down tail undulation in the vertical plane. It seems unlikely that any of these animals were particularly fast swimmers.

PurposeTo assess anterior scleral canal opening (ASCO) offset relative to Bruch's membrane opening (BMO) (ASCO/BMO offset) so as to determine neural canal direction, obliqueness, and minimum cross-sectional area (NCMCA) in 362 healthy eyes.DesignCross-sectional study.MethodsAfter optical coherence tomography optic nerve head and retinal nerve fiber layer thickness (RNFLT) imaging, BMO and ASCO were manually segmented. Planes, centroids, size, and shape were calculated. Neural canal direction was defined by projecting the neural canal axis vector (connecting BMO and ASCO centroids) onto the BMO plane. Neural canal obliqueness was defined by the angle between the neural canal axis and the BMO plane perpendicular vector. NCMCA was defined by projecting BMO and ASCO points onto a neural canal axis perpendicular plane and measuring the area of overlap. The angular distance between superior and inferior peak RNFLT was measured, and correlations between RFNLT, BMO, ASCO, ASCO/BMO offset, and NCMCA were assessed.ResultsMean (SD) NCMCA was significantly smaller than either the BMO or ASCO area (1.33 (0.42), 1.82 (0.38), 2.22 (0.43) mm2, respectively), and most closely correlated to RNFLT (P < .001, R2= 0.158). Neural canal direction was most commonly superior-nasal (55%). Mean neural canal obliqueness was 39.4° (17.3°). The angular distance between superior and inferior peak RNFLT correlated to neural canal direction (P ≤ .008, R2= 0.093).ConclusionsASCO/BMO offset underlies neural canal direction, obliqueness, and NCMCA. RNFLT is more strongly correlated to NCMCA than to BMO or ASCO, and its peripapillary distribution is influenced by neural canal direction.

PURPOSE Acetazolamide (ACZ) lowers intraocular pressure (IOP), acutely in normal eyes and both acutely and chronically in eyes with glaucoma, and cerebrospinal fluid pressure (CSFp), chronically in patients with idiopathic intracranial hypertension (IIH). We hypothesize chronic daily ACZ would significantly reduce IOP and contribute to a translaminar pressure gradient change reflected by alteration in the CSFp-IOP difference and the deformation of the neural canal in patients with IIH and no glaucoma. PATIENTS AND METHODS Before randomization to ACZ or placebo treatment for 6 months, 165 participants in the IIH Treatment Trial had evaluations that included Goldmann applanation, CSFp measurement, and optical coherence tomography determination of the neural canal deformation. These measures were repeated at the 6-month outcome. RESULTS The IOP was not significantly decreased from baseline at 1, 3, or 6 months in eyes in both treatment groups. At month 6, the amount of ACZ or weight modification did not correlate with any IOP change. The 6-month mean change in neural canal deformation was 0.96 and -0.04 (P=0.001) and in CSFp was -128 and -38 mm H2O (P=0.001), but CSFp-IOP difference change was not significant, in the ACZ and placebo groups, respectively. CONCLUSIONS ACZ does not reduce the IOP in eyes without glaucoma but does decrease the pathologic elevated CSFp, providing evidence that normal systems can compensate for chronic medication effects. The CSFp-IOP is not a direct marker of translaminar pressure gradient and the ACZ normalization of the neural canal deformation appears due to CSFp reduction alone.

A partial skeleton of a sauropod dinosaur, Museum of Western Colorado 8028, was recovered from the Upper Jurassic Morrison Formation near Snowmass, Colorado, USA, and in 2014 it was referred to Haplocanthosaurus sp. The material includes four proximal caudal vertebrae, which are unique in having strongly amphicoelous vertebral bodies, in which the centrum is reduced to a thin vertical plate of bone between the concave articular surfaces, and neural canals that are laterally and ventrally expanded and strongly sloped relative to the centrum. To reconstruct the soft tissues that left these traces on the skeleton, we rebuilt these vertebrae using both physical and digital techniques. We CT scanned the specimens, generated digital models, 3D-printed the vertebrae, physically sculpted missing material onto the printed models, optically scanned the sculpted vertebrae to create second-generation digital models, and finally, retro-deformed and articulated those digital versions of the vertebrae. The spaces between the deeply amphicoelous caudal centra were likely filled by large, ellipsoidal intervertebral discs, as in the amphicoelous vertebrae of Sphenodon and gekkotan lizards. The expanded neural canals remain enigmatic. In ostriches, the lumbosacral spinal cord is expanded laterally and ventrally in each vertebra, lending the spinal cord a shape that roughly resembles beads on a string. Similar spinal cord morphology might explain the expanded neural canals in the Snowmass Haplocanthosaurus, but it is not clear why a relatively small-bodied, small-tailed sauropod would need such a spinal expansion, given that similar expansions have not been reported in larger-bodied and larger-tailed taxa.

Birds are unique among extant tetrapods in having pneumatic diverticula of the lungs and air sacs that pass among the viscera and muscles, under the skin, and into the skeleton. In addition, some birds also have supramedullary diverticula inside the neural canal, adjacent to the spinal cord. The anatomy of the supramedullary diverticula has only been documented in a handful of birds to date. Using CT scans, we surveyed the morphology of the supramedullary diverticula in a phylogenetically broad sample of extant birds. Although supramedullary diverticula are present in some small-bodied taxa such as hummingbirds and pigeons, the diverticula are typically larger and more complex in large forms such as ostriches and pelicans. Absence of these diverticula in loons and grebes is consistent with the lack of skeletal pneumatization in diving birds. Other absences, for example in the kestrel, are less explicable. When present, the supramedullary diverticula are best developed in presacral vertebrae, but only occasionally present in the synsacrum, and rarely present in caudal vertebrae. In most taxa we have surveyed, the diverticula are not continuous craniocaudally, but exist as separate segments extending fore and aft from each intervertebral joint, as documented by Müller for the pigeon. Occasionally supramedullary diverticula communicate with interosseous diverticula through foramina in the wall or roof of the neural canal. These foramina are osteological correlates of supramedullary diverticula and allow the presence of these diverticula to be inferred in dry skeletal material and fossil organisms.

The presence of a pathology in the vertebral column of the early Permian mesosaurid specimen ZPAL R VII/1, being one of the oldest amniotic occurrences of congenital scoliosis caused by a hemivertebra, was recently recognized. Here we provide CT data to further characterize the phenomenon. The affected hemivertebra is wedged (incarcerated) between the preceding and succeeding vertebrae. The neural canal is misshapen but continuous and the number of dorsal ribs on each side of the specimen corresponds with the number of the vertebrae, documenting its congenital (homeobox-related) derivation.

We have studied the comparative anatomy of arterial plexuses (retia mirabilia) related to supply of the central nervous system in two closely related species of toothed whales - narwhal (Monodon monoceros) and beluga Delphinaterus leucas). In both species, retia originate from major vessels in the neck, thorax, and lumbar regions, then extend into the neural canal and cranium to supply the spinal cord and brain. The system generally consists of arteries embedded in a matrix of fatty connective tissue. Constituent vessels are only occasionally reated to veins or venous sinuses. Though retial anatomy is similar in the two species, there are two related features that appear species specific: (1) amount of retia originating from the supreme intercostal arteries and (2) thoracic retial size. Both are larger in the narwhal, as are values for hematocrit and hemoglobin concentration, which, in this study, we use as indices of diving ability. Our data are consistent with the hypothesis that the retia are in some way linked to diving ability. The nature of this link is not known; however, we discuss our results in the context of the most popular hyotheses of retial function.

A 4-year-old girl with no significant medical or family history presented with toe walking, leg pain, unsteady gait and frequent falls for 2 months. Examination revealed upper motor neuron signs in the lower extremities. Laboratory tests were normal including creatinephosphokinase and lactate dehydrogenase. Brain and lumbar spine MRI were normal. MRI cervical and thoracic spine showed a large intradural and extradural mass arising from the right C7 nerve root, widening of the neural canal with evidence of cord compression. She underwent C6–C7 laminectomy with excision of the tumour. Pathology revealed spindle cell tumour with extensive expression of S100 protein and CD56, with Ki-67 proliferation index of 1%–2% consistent with benign schwannoma. She made an excellent recovery following surgery and physiotherapy sessions. Review of literature shows rare reported case of schwannoma prior to the third decade of life.

For adequate access to spinal nerve structures, less traumatic resection of bone structures use of high-speed drill is advisable.In 33 patients with spinal trauma surgery was performed using high-speed pneumatic drill “Midas Rex Legend” (Medtronic).Conclusions. 1. The advantages of medical drill are: decrease in physical activity for a surgeon when handling to the spine bone structure; good anatomical access to spine structures; trauma reduction of nerve and bone structures of the spine.2. To improve access to the neural canal and partial resection of the bone structures of the spine use a high-speed drill is preferable.3. Drill use gives the possibility to perform organpreserving spinal surgery.4. Surgical approach using high-speed drill gives the possibility to expand indications for manipulations in hard-to-reach anatomical areas of the spine.

This study tests the association of vertebral neural canal (VNC) size and age-at-death in a Portuguese skeletal collection from the 19th-20th century. If the plasticity and constraint model best explains this association, VNC size would be negatively related to mortality risk. If the predictive adaptive response (PAR) model is a better fit, no association can be inferred between VNC size and age-at-death. Ninety individuals were used in this study. The anteroposterior and transverse diameters of all vertebrae were measured. A Cox regression analysis was performed by sex to assess the effect of VNC size on age-at-death, after adjusting for the effects of year of birth and cause of death. Several measurements of VNC diameters have a statistically significant effect on age-at-death, but when the covariates were considered, this association became non-significant. The PAR model seems the best fit to explain the relation between VNC and age-at-death. Individuals who went through stressful events early in life were prepared to face a stressful environment later in life, allowing them to cope with adversity without affecting longevity. However, developmental plasticity may be buffered by maternal capital accumulated over several generations, and health hazards encountered throughout life can contribute to health outcomes and longevity.

Purpose: To compare neural canal opening (NCO) with the clinical optic disc margin (DM) seen and to investigate the planarity of the NCO in normal human optic nerve heads (ONH). Methods: Sixteen eyes were imaged. Twelve healthy eyes were selected for planarity and 9 for NCO and DM correspondence. All subjects were subjected to a visual field examination, stereo disc photograph (SDP), scanning laser ophthalmoscopy, clinical examination with a fellowship trained glaucoma specialist, and optical coherence tomography imaging. Three reviewers delineated the NCO and inner limiting membrane on optical coherence tomography images. The clinical DM was delineated by a glaucoma specialist while viewing SDPs. Plane error was calculated for NCO and for Bruch membrane (BM) at distances 80 and 120 μm from NCO. Results: The NCO segmentation interrater variability was low with an average coefficient of variation of 2.7%. A regional variation of the SDP and NCO correspondence was observed, wherein the temporal region had the largest coefficient of variation. The plane error of the NCO and BM were similar and was approximately 12 μm, which is small relative to an average DM diameter of 1.7 mm. Conclusions: The BM opening has a good correspondence with the clinical DM seen in SDPs. NCO delineation seemed to be reliable. The BM and NCO are relatively planar in normal humans and can be further evaluated for longitudinal studies to observe stability.

The original hypodigm of the controversial mid-Cretaceous Moroccan dinosaur Sigilmassasaurus brevicollis is redescribed, and the diagnosis of the taxon is revised. Unambiguously referred material is restricted to cervical and anterior dorsal vertebrae sharing apomorphies with the holotype. A newly recognized diagnostic character of Sigilmassasaurus is the absence of anterior and posterior interzygapophyseal laminae of the neural arch, so that the neural spine directly meets the dorsal margin of the neural canal. A phylogenetic analysis supports the inclusion of Sigilmassasaurus in Tetanurae but not in Carcharodontosauridae. Sigilmassasaurus is distinct from all other theropods known from comparable material and is thus retained as a valid taxon.

We analysed retinal nerve fibre layer (RNFL) defects in eyes with normal circumpapillary RNFL (cpRNFL) thickness using posterior pole asymmetry analysis (PPAA) and investigated the parameters of Bruch membrane opening (BMO) and neural canals using enhanced depth imaging spectral domain optical coherence tomography (EDI-SDOCT). A total of 112 preperimetric glaucomatous eyes of 92 patients were examined to obtain cpRNFL thickness using SD-OCT. Posterior pole asymmetry analysis (PPAA) and central cross-sectional images of the optic nerve head (ONH) were obtained using EDI-SDOCT. Minimal and horizontal distances between the BMO and ONH surfaces (BMOM, BMOH) and the terminal of retinal pigment epithelium (RPE) and ONH surfaces (RPEM, RPEH) were measured. The distribution of the absolute black cells in PPAA was more concentrated in eyes with “U”-shaped neural canals (p

Herniated nucleus pulposus (HNP) in the lumbar spine is usually found in the neural canal (in the intracanal space) and occasionally in the extracanal space, where it is known as a lateral HNP. HNP is rarely found simultaneously in both spaces. However, we experienced such a case in a 48-year-old man who presented with right leg pain and lower back pain that had lasted for more than a year. MRI revealed HNP in both the right intracanal and extracanal spaces at L2-L3. A transforaminal approach was used to complete a percutaneous endoscopic discectomy. An 8-mm incision was made with the patient under local anesthesia, and the percutaneous endoscope was inserted at the affected disc space. First, the HNP fragments in the intracanal space were removed, and then the cannula and endoscope were extracted to the extracanal space where the extracanal fragments were removed. Two hours after the surgery, the patient stood and walked. Right leg pain and lower back pain had disappeared. Unlike other techniques such as Love's procedure and the microendoscopic discectomy technique, the use of a transforaminal approach with the percutaneous endoscopic technique enables the HNP fragments in the intracanal and extracanal spaces to be removed at the same time with a single approach.

Rationale:Neuraxial anesthesia is a commonly used type of regional anesthesia. Cauda equina syndrome is an unusual and severe complication of neuraxial anesthesia, and is caused by damage to the sacral roots of the neural canal. We present a case of cauda equina syndrome following spinal ane

The early Middle Cambrian Monastery Creek Phosphorite (Beetle Creek Formation, Queensland, Australia) contains an assemblage of disarticulated echinoderm ossicles that are exquisitely preserved. Amongst this material we recognize pelmatozoan brachials, radials, basals and holomeric columnals. Although we cannot reconstruct the complete animal with precision, these elements represent the oldest known pelmatozoan with crinoid-like appendages. Key elements include isotomously to heterotomously branched uniserial appendage plates with a tripartite adoral food groove, a longitudinal central canal interpreted as housing entoneural nerve, and differentiated articulation facets. There are also epispire-bearing radials bearing one to four arm insertion-facets, each one pierced by a central neural canal. These canals run internal towards the oral area beneath the external food groove. Co-occuring material includes single truncated cone-shaped basals and holomeric columnals, both with a similar articulation pattern, and irregular, epispire-bearing thecal plates. This mosaic of crinozoan (uniserial isotomous to heterotomous arms with neural canal), blastozoan (epispire-bearing thecal plates, appendage leading to oral thecal food groove without direct connection with body cavity) and apomorphic characters (circumoral instead of basal entoneural plexus) is unexpected and demonstrates that crinoid-like pelmatozoans with uniserial, branched arms appeared significantly earlier than the Tremadocian, when the first articulated crinoid skeletons are found. It also raises questions about the polyphyletic appearance of feeding appendages among pelmatozoan echinoderms.

Background context Bone morphogenetic protein-2 (BMP-2) (Infuse) has been approved for use in anterior lumbar fusion in conjunction with an LT cage. However, off-label use is seen with anterior cervical fusion, posterior lumbar interbody fusion (PLIF), and transforaminal lumbar interbody fusion (TLIF). The Federal Food and Drug Administration trial of BMP-2 in a PLIF application was halted because of a high incidence of ectopic bone forming in the neural canal (75%). The authors did not find a correlation between ectopic bone and increased leg pain. They concluded that the ectopic bone was a radiographic phenomenon and not associated with clinical findings. Complications using BMP in the cervical spine have been reported. Heretofore, there has not been a similar warning voiced for use of BMP in a lumbar PLIF or TLIF. Purpose The purpose was to report five cases of ectopic bone in the canal associated with PLIF/TLIF off-label use of BMP-2 potentially contributing to abnormal neurologic findings. Study design/setting This is an observational cohort study of patients referred to a tertiary care private medical center. Methods This was a retrospective chart review of patients referred to a tertiary spine institute with complications after surgery where BMP-2 had been used in an off-label PLIF or TLIF application. Patient demographics, operating room (OR) notes from the index BMP surgery, imaging studies, and current clinical status were reviewed. Results Five cases of ectopic bone in the spinal canal with potential neurologic compromise were identified. Conclusions It does appear that ectopic bone in the spinal canal associated with BMP-2 use in PLIF or TLIF may contribute to symptomatic neurologic findings in rare cases. Revision surgeries are difficult. This article challenges a previous publication, which concluded that the high incidence of ectopic bone was of no clinical significance. Isolating BMP anteriorly in the disc space using layered barriers of bone graft between the BMP and the annular defect may reduce the incidence of ectopic bone in the spinal canal. Surgeons need to weigh the benefits versus risks of any technology used off label when making treatment decisions with their patients.

Lumbar spinal stenosis is a narrowing of spinal canal or neural foramina producing root ischaemia and neurogenic claudication[1–3]. Both the neural canal and foramen are narrowed with the spine in extension and opened in flexion. Patients are usually sixty years or over and present with unilateral or bilateral leg pain with or without back pain. The pain is worse on walking and if the patient is upright and relieved by sitting or bending forward[1–3]. With increasingly ageing population this is a common problem and difficult to deal with as many of the elderly patients have associated co-morbidities making them unsuitable for conventional decompressive surgery[4, 5]. Although lumbar spinal stenosis is one of the most frequent indications for spinal surgery in patients over 65 years of age[7], deciding the most appropriate procedure is a challenge to the clinicians. X-STOP interspinous implant is a titanium device. It was developed to prevent extension and also increase the dimension of spinal canal and neural foramina[5]. We are reporting the clinical outcome and patient satisfaction following indirect decompression with X-STOP.

Background context Conventional transpedicular decompression of the neural canal requires a considerable amount of lamina, facet joint and pedicle resection. The authors assumed that it would be possible to remove the retropulsed bone fragment by carving the pedicle with a high-speed drill without destroying the vertebral elements contributing to spinal stabilization. In this way, surgical treatment of unstable burst fractures can be performed less invasively. Purpose The purpose of this study is to demonstrate both the possibility of neural canal decompression through a transpedicular approach without removing the posterior vertebral elements, which contribute to spinal stabilization, and the adequacy of posterior stabilization of severe vertebral deformities after burst fractures. Study design Twenty-eight consecutive patients with complete or incomplete neurological deficits as a result of the thoracolumbar burst fractures were included in this study. All patients had severe spinal canal compromise (mean, 59.53%±14.92) and loss of vertebral body height (mean, 45.14%±7.19). Each patient was investigated for neural canal compromise, degree of kyphosis at fracture level and fusion after operation by computed tomography and direct roentgenograms taken preoperatively, early postoperatively and late postoperatively. The neurological condition of the patients was recorded in the early and late postoperative period according to Benzel-Larson grading systems. The outcome of the study was evaluated with regard to the adequate neural canal decompression, fusion and reoperation percents and neurological improvement. Methods Modified transpedicular approach includes drilling the pedicle for removal of retropulsed bone fragment under surgical microscope without damaging the anatomic continuity of posterior column. Stabilization with pedicle screw fixation and posterior fusion with otogenous bone chips were done after this decompression procedure at all 28 patients included in this study. Results Twenty-three of 28 patients showed neurological improvement. The percent of ambulatory patients was 71.4% 6 months after the operation. The major complications included pseudarthrosis in five patients (17.8%), epidural hematoma in one (3.5%) and inadequate decompression in one (3.5%). These patients were reoperated on by means of an anterior approach. Of the five pseudarthrosis cases, two were the result of infection. Conclusion Although anterior vertebrectomy and fusion is generally recommended for burst fractures causing canal compromise, in these patients adequate neural canal decompression can also be achieved by a modified transpedicular approach less invasively.

The claustrum, one of the Weberian ossicles of otophysans, is here proposed as homologous to the accessory neural arch (ANA) of lower teleosts. This idea is based on structural and topographical correspondence, as well as on ontogenetic timing of differentiation and ossification. Claustrum and ANA are similar in general shape and occupy the same position relative to other vertebral structures. They are both derived from paired cartilage precursors that differentiate around the anterior part of the neural canal. Also, chondrification and ossification of ANA and claustrum are markedly delayed relative to surrounding elements, such as regular neural arches and supraneurals. The new hypothesis implies that the accessory neural arch is actually present in otophysans (modified as claustrum) and therefore that its loss cannot be considered as an ostariophysan synapomorphy. Loss of a separate accessory neural arch in adults is instead an additional synapomorphy of Gonorynchiformes, a loss homoplastic wit...

Chemonucleolysis must relieve sciatic pain by some means other than the removal of the disc protrusion from the neural canal, because the protrusion characteristically persists despite the resolution of sciatic pain. This paper analyzes the mechanism of symptom production in sciatica and identifies how chemonucleolysis relieves these symptoms. Pressure can be exerted on a nerve root by a disc protrusion without compression against the posterior wall of the neural canal. This pressure is the result of tension produced in the nerve root when it is deformed by the disc protrusion. A previously unrecognized principle of nerve root-disc protrusion mechanics is identified. For a given disc protrusion, narrowing the disc reduces the tension in the nerve root and therefore the pressure on the nerve root; conversely, widening the disc increases the tension and pressure on the nerve root. Disc narrowing is in itself a mechanism by which chemonucleolysis relieves sciatic pain.

Study design: Original article. Objective: The authors present seven cases who underwent one-stage suboccipital, C1 and/or C2 posterior decompression and fusion by Luque rod, wiring and autogenic bone graft for occipito-cervical instability and neural compression. Setting: Chang Gung University and Medical Center at Kaohsiung, Taiwan. Method: Since January 1996, 20 cases of craniovertebral and upper cervical spinal instability were encountered. Seven of these cases had no neurological improvment under Cone-Barton Skeletal traction. Imaging studies revealed poor reduction with persistent neural compression. One patient underwent unsuccessful anterior trans-oral vertebrectomy for decompression. All patients underwent posterior suboccipital craniectomy, C1 and/or C2 laminectomy for decompression. Contoured Luque rod with wiring and autogeneic bone graft was used for craniocervical fusion. After surgical treatment, halo-vest or sterno-occipito-mandibular immobilizer (SOMI) was used for 3–6 months Results: Suboccipital craniectomy and C1 laminectomy could afford a 30–50% increment of anteroposterior diameter in the neural canal and effective decompression of the low medulla and cord. All patients made neurological improvement. The ASIA-MIS scores improved from pre-operative 49 (mean) to 78. Four patients can walk without any support. There were no major complications except for one case requiring readjustment of the halo-vest brace. Conclusion: The authors recommend this procedure as one choice for relieving craniocervical instability with neurological compromise. A programmed rehabilitation will afford better neurological improvement. Spinal Cord (2001) 39, 101–108.

From its numerical composition, the central nervous system (CNS) of the ascidian larva is one of the simplest known nervous systems having a chordate plan. Fewer than 350 cells together constitute a caudal nerve cord, an interposed visceral ganglion containing motor circuits for swimming and, rostrally, an expanded sensory vesicle containing major sensory and interneuron regions of the CNS. Some cells are ependymal, with ciliated surfaces lining the neural canal, while others are clearly either sensory receptors or motoneurons, but most are distinguishable only on cytological grounds. Although reassignments between categories are still being made, there is evidence for determinancy of total cell number. We have made three-dimensional cell maps either from serial semithin sections, or from confocal image stacks of whole-mounted embryos and larvae stained with nuclear markers. Comparisons between the maps of neural tubes in embryos of successive ages, that is, between cells in one map and their progeny in older maps, enable us to follow the line of mitotic descent through successive maps, at least for the caudal neural tube. Details are clear for the lateral cell rows in the neural tube, at least until the latter contains approximately 320 cells, and somewhat for the dorsal cell row, but the ventral row is more complex. In the hatched larva, serial-EM reconstructions of the visceral ganglion reveal two ventrolateral fibre bundles at the caudalmost end, each of 10-12 axons. These tracts include at least five pairs of presumed motor axons running into the caudal nerve cord. Two pairs of axons decussate. Complementing this vertebrate feature in the CNS of the larval form of Ciona, we confirm that synapses form upon the somata and dendrites of its neurons, and that its motor tracts are ventral.

The need to segment multiple interacting surfaces is a common problem in medical imaging and it is often assumed that such surfaces are continuous within the confines of the region of interest. However, in some application areas, the surfaces of interest may contain a shared hole in which the surfaces no longer exist and the exact location of the hole boundary is not known a priori. The boundary of the neural canal opening seen in spectral-domain optical coherence tomography volumes is an example of a “hole” embedded with multiple surrounding surfaces. Segmentation approaches that rely on finding the surfaces alone are prone to failures as deeper structures within the hole can “attract” the surfaces and pull them away from their correct location at the hole boundary. With this application area in mind, we present a graph-theoretic approach for segmenting multiple surfaces with a shared hole. The overall cost function that is optimized consists of both the costs of the surfaces outside the hole and the cost of boundary of the hole itself. The constraints utilized were appropriately adapted in order to ensure the smoothness of the hole boundary in addition to ensuring the smoothness of the non-overlapping surfaces. By using this approach, a significant improvement was observed over a more traditional two-pass approach in which the surfaces are segmented first (assuming the presence of no hole) followed by segmenting the neural canal opening.

Background The boundary separating the posterior columns of the spinal cord is formed by the lateral margins of the neural groove approximating to form the neural canal. In anatomy texts this line is usually drawn as continuous, uniform, centered, and straight. It is universally termed posterior or dorsal, median “septum.” Methods Sections from the cervical and lumbar enlargements and the mid-thoracic region were examined from 35 human autopsy specimens from 20 weeks gestation to 70 years with no history of spinal cord disease or trauma. They were stained with Masson's trichrome, and by immunohistochemistry for collagen types 1 and 4, and for glial fibrillary acidic protein (GFAP). Results One or more variations were found in the position character, shape, or extent of the line at one or more levels in every case. There was no midline staining for collagen other than that associated with blood vessels. There is intense immunoreactivity for GFAP from 20 weeks gestation to 35 weeks diminishing thereafter. When the posterior columns are separated the “septum” divides. Conclusion In the absence of any collagen this line of separation is more akin to a raphe than a septum. Inasmuch as there is an immediately adjacent subarachnoid posterior median septum it would be advantageous to re-name this intraspinal structure “dorsal” or “posterior” median raphe. © 1996 Wiley-Liss, Inc.

A total of 116 surgically treated patients with unstable fractures of the thoracic and lumbar spines were subjected to this study on basis of the simple radiographic and CT findings of the injured spinal column and neurological changes at the injured cord and/or roots level. Among them 50 patients were paraplegics and 66 patients were non-paraplegics. Spine fracture patterns shown on axial CT images were classified into five types on the basis of the fracture severity of vertebral body associating the canal compromise by the encroached fracture fragments from middle column and posterior element. Type I: vertical linear fracture through mid-anterior and posterior elements; Type II: retropulsed fragment in the canal with intact posterior element; Type III: retropulsed fragment in the canal with fracture of the posterior element; Type IV: severe comminution of body and disruption of posterior element around the canal; Type V: fracture-dislocation of comminuted vertebral body and neural arch (with or without double margin sign and with or without vacant facet sign). Displacement of vertebral body on lateral plane radiograms showed significant difference ([Formula: see text] < 0.001) between the non-paralytics and paralytics, but there were no differences in kyphotic angles and anterior body height loss between the two groups. Neurological injury was highly complicated in cases of the fracture-dislocation (20 out of 22 patients: 90.9%). Unstable fracture which occurred in the thoracic level showed high incidence of neurological injuries [24 out of 28 patients (85.7%)]; complete paralysis in 20 (71.4%) out of 28 patients in comparison with that of the thoracolumbar and lumbar fractures. Anteroposterior (AP) diameter of the compromised neural canal and percentile surface area of the compromised canal showed significant differences between the paralytics and non-paralytics (canal diameter: [Formula: see text]