Anterior Median Fissure Research Articles

A morphometric analysis of the circumolivary fiber bundle of the human brainstem.

The circumolivary fiber bundle (CFB) is considered to be an anatomical variation, which can be found on the surface of the human medulla oblongata. The macroscopical fiber bundle runs downwards from either the anterior median fissure, the pyramid, or both, around the inferior pole of the olive and turns upwards to reach the restiform body of the inferior cerebellar peduncle. Multiple fiber systems feed the constitution of the CFB (collateral corticospinal fibers, fibers connecting to the reticular formation, anterior external arcuate fibers). With this examination we provide a systematic analysis of the frequency of occurrence (6.14%), size, and laterality of the CFB. Including all three fiber bundle parts (descending part, genu, and ascending part), the left-sided sizes were increased. Likewise, the appearance of an unilateral left-sided CFB could be detected in more than 60% of our cases. Our morphometrical analysis currently covers the largest sample of investigated brainstem sides (n = 489) so far. This investigation should widen the perspective on how anatomists, neuroradiologists, and neurosurgeons expect the anterolateral surface of the human medulla oblongata.

Highest Resolution MicroCT Scan of the Human Brainstem Reveals Putative Anatomical Basis for Infrequency of Medial Medullary Syndrome

Posterior circulation or brainstem strokes account for approximately 25% of acute strokes, affecting arterial territories in the medial or lateral divisions of the midbrain, pons, or medulla. Out of all brainstem regions, medial medullary strokes are the rarest, making up fewer than 1% of reported posterior circulation cases. Medial Medullary Syndrome (MMS) is a clinical triad of contralateral hemiplegia, loss of fine touch / position sense, and hypoglossal palsy that may result from ischemia or hemorrhage of small perforating branches of the anterior spinal, vertebral, or basilar arteries. The relative infrequency of MMS is surprising given the prevalence of stroke in other perforator artery territories as these vessels are more susceptible to small vessel disease. Indeed, small perforator‐type vessels from other parent arteries contribute to more than 50% of all strokes in a population (e.g. lacunar branches of the middle cerebral artery and paramedian pontine branches of the basilar artery). This disparity in prevalence remains unexplained in part because clinical anatomy has been historically limited by an unfavorable ratio of fine blood vessel size to coarse MRI and CT scan resolution. Here, we capture and digitally dissect the highest‐ever‐resolution diffusible iodine‐based contrast‐enhanced CT (diceCT) scanned images of a cadaveric brainstem to map MMS arteries in never‐before‐captured detail. A cadaveric brain was fixed in formalin and stained using a 3% concentration of Lugol’s iodine (I2KI) for 12.5 weeks (refreshed every 2 weeks), before microCT scanning at 57 microns (a scale twice as fine as any previous scans). The resulting image stack was segmented in Avizo 2020.1. Results show that within the MMS anterior spinal artery territory, there are numerous, small sulcal artery branches perforating the medulla within the anterior median fissure. These branches proceed in parallel through the anteroposterior depth of the medulla as expected; however, we also identify a network of intraparenchymal, rostrocaudal anastomoses between these sulcal perforating branches. This network of intraparenchymal sulcal artery anastomoses has never been described, and may provide a significant collateral supply of oxygenated blood flow throughout the medial medulla. By ramifying deeper tissues, this anastomosis can help explain the infrequency of MMS.

Anterior Spinal Cord Ischemia due to an Acute Aortic Intramural Type B Hematoma

Anterior Spinal Cord Ischemia due to an Acute Aortic Intramural Type B Hematoma

Highest resolution microCT scan of the human brainstem reveals putative anatomical basis for infrequency of medial medullary syndrome

Ischemic strokes affecting the medial medulla are exceedingly rare. The anatomical basis for the relative infrequency of this stroke syndrome has been largely uninvestigated due to historically coarse MRI and CT scan resolution. We capture and digitally dissect the highest-ever-resolution diffusible iodine-based contrast-enhanced CT (diceCT) scanned images of a cadaveric brainstem to map arterial territories implicated in medial medullary infarctions. 3D reconstructions show that within the anterior spinal artery territory previously implicated in medial medullary syndrome (MMS), there are numerous, small sulcal artery branches perforating the medulla within the anterior median fissure. These branches proceed in parallel through the anteroposterior depth of the medulla as expected; however, we also identify a network of intraparenchymal, rostrocaudal anastomoses between these sulcal perforating branches. This network of intraparenchymal sulcal artery anastomoses has never been described and may provide a significant collateral supply of oxygenated blood flow throughout the medial medulla. By ramifying deeper tissues, these anastomoses can help explain the infrequency of MMS.

Development of the Arterial Supply of the Spinal Cord Tissue Based on Radioanatomical and Histological Studies in Cattle

PurposeAngiographic techniques have gained increasing importance in suspected vascular disease of the spinal cord. This demands an advanced understanding of spinal cord blood vessel anatomy and its embryologically founded broad spectrum of variations. The aim of this study was to improve knowledge on contentious issues concerning the development of spinal cord arterial supply in higher mammals and to offer visual information of high didactic value.MethodsThe prenatal development was examined in cattle, using multiplanar high-resolution microangiography of injected specimens and microscopic sections. The gestational ages of the 15 specimens were between the late embryonic and the early fetal period (5–11 weeks). Microangiography of the human spinal cord from an earlier published study were used to envisage an adult arterial vascularization pattern in higher mammals.ResultsEstablishment of the unpaired anterior spinal artery (ASA) goes through two procedures of reconfiguration until achieving its final design. Regression of the primarily established anteromedian tract is observed in cattle fetuses of 9–10 weeks. Return to the ontogenetic disposition of bilateral symmetry and a burst of vascularization from all parts of the spinal meninges follow and include the anterior median fissure as a preferred vascular pathway. Large sulcal/central arteries longitudinally anastomosing between each other emerge on both sides of the midline. The embryological pattern of exclusive peripheral medullary supply must have been converted into a combined system of predominant central (centrifugal) supply of the enlargements before a final unpaired ASA can be reconstructed.ConclusionPrevious investigators focused on the early embryonic development of spinal cord arteries and missed the profound remodeling of the vascular architecture in the early fetal period.

MRI T2-Hyperintense Signal Structures in the Cervical Spinal Cord: Anterior Median Fissure versus Central Canal in Chiari and Control-An Exploratory Pilot Analysis.

Cervical spine axial MRI T2-hyperintense fluid signal of the anterior median fissure and round hyperintense foci resembling either the central canal or base of the anterior median fissure are associated with a craniocaudad sagittal line, also simulating the central canal. On the basis of empiric observation, we hypothesized that hyperintense foci, the anterior median fissure, and the sagittal line are seen more frequently in patients with Chiari malformation type I, and the sagittal line may be the base of the anterior median fissure in some patients. Saggital line incidence and the incidence/frequency of hyperintense foci and anterior median fissure in 25 patients with Chiari I malformation and 25 contemporaneous age-matched controls were recorded in this prospective exploratory study as either combined (hyperintense foci+anterior median fissure in the same patient), connected (anterior median fissure extending to and appearing to be connected with hyperintense foci), or alone as hyperintense foci or an anterior median fissure. Hyperintense foci and anterior median fissure/patient, hyperintense foci/anterior median fissure ratios, and anterior median fissure extending to and appearing to be connected with hyperintense foci were compared in all, in hyperintense foci+anterior median fissure in the same patient, and in anterior median fissure extending to and appearing to be connected with hyperintense foci in patients with Chiari I malformation and controls. Increased sagittal line incidence (56%), hyperintense foci (8.5/patient), and anterior median fissure (4.0/patient) frequency were identified in patients with Chiari I malformation versus controls (28%, 3.9/patient, and 2.7/patient, respectively). Increased anterior median fissure/patient, decreasing hyperintense foci/anterior median fissure ratio, and increasing anterior median fissure extending to and appearing to be connected with hyperintense foci/patient were identified in Chiari subgroups. A 21%-58% increase in observed anterior median fissure extending to and appearing connected to hyperintense foci in the entire cohort and multiple sagittal line subgroups compared with predicted occurred. In addition to the anticipated increased incidence/frequency of sagittal line and hyperintense foci in patients with Chiari I malformation, an increased incidence and frequency of anterior median fissure and anterior median fissure extending to and appearing to be connected with hyperintense foci/patient were identified. We believe an anterior median fissure may contribute to a saggital line appearance in some patients with Chiari I malformation. While thin saggital line channels are usually ascribed to the central canal, we believe some may be due to the base of the anterior median fissure, created by pulsatile CSF hydrodynamics.

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Anterior fissure, central canal, posterior septum and more: New insights into the cervical spinal cord gray and white matter regional organization using T1 mapping at 7T

T1 mapping lacks specificity toward a single particular biological feature, however it has the potential to discriminate spinal cord regional tissue organization and characterize tissue microstructural impairments occurring in neurodegenerative pathologies. In this exploratory work, T1 mapping of the cervical spinal cord with a 300-μm in-plane resolution was performed on fourteen healthy subjects at 7T, using the MP2RAGE sequence. Individual images from C1 to C7 vertebral levels provided a clear delineation of spinal cord anatomical details and substructures including motor columns within gray matter (GM) horns, anterior median fissure, central canal, ventral, lateral and dorsal white matter (WM) fasciculi, and posterior median septum. Group studies highlighted regional T1 differences between regions of interest so far hardly visible at lower spatial resolution. Two-dimensional averaged T1 maps and manual parcellation of GM and WM substructures were built based on these data. Benefiting from the very high spatial resolution achievable at ultra-high field for T1 mapping, this work contributes to improve the in vivo characterization of the cervical spinal cord. By allowing investigation within a wider range of functional regions, it also opens new perspectives for pathology diagnosis such as motor neuron disease, neuropathic pain or refined investigation of neurodegeneration.

Life of Gerard Blasius, and His Description of the Spinal Cord

Gerard Blasius (Blasius or Blaes) is a Dutch physician, chemist and anatomist. In this study, Gerard Blasius’ life, books and his contributions to neuroanatomy were researched. Blasius has written dozens of books. It is accepted that first important study of spinal cord is belong to Blasius. He depicted the horizontal section of the spinal cord and represented the white and gray matters in these drawings successfully. Besides, in these drawings, spinal ganglion, anterior median fissure, posterior median sulcus, brainstem, terminal filum, cerebellum, vertebral artery, anterior spinal artery and spinal dura mater are seen remarkably. In addition to being one of the leading scientists in anatomy, zootomy, botany and chemistry, Blasius’ description and drawing of spinal cord in detail must be seen as a success beyond the his time.

Split-Cord Malformation of the Cervical Spinal Cord Following Dorsal Root Entry Zone Lesioning Surgery

The authors report a rare case of a 54-year-old man who developed an asymptomatic cleft within the cervical spinal cord at C7-T1 following Dorsal Root Entry Zone (DREZ) lesioning surgery. The patient presented to the authors’ institution with neuropathic pain from a left brachial plexopathy resulting from a lower trunk avulsion. The initial MRI at 6 months post-injury confirmed preganglionic avulsions of the left C7, C8 and T1 nerve roots. Of note, there was a prominent anterior median fissure at the C7-T1 spinal level. He underwent a DREZ lesion 8 months after the injury. Subsequent MRI studies showed a progressive near complete split within the cervical cord at C7- T1. The patient did not develop any new neurological deficits. It remains unclear whether this observation was a sequela of the root avulsion or the DREZ surgery.

Morphological Patterns of the Anterior Median Fissure in the Cervical Spinal Cord Evaluated by Computed Tomography After Myelography.

ObjectiveComputed tomography following myelography (CTM) revealed an unusual flow of contrast dye into the anterior median fissure (AMF) in a patient with cervical spondylotic myelopathy. Since then, several AMF configurations have been observed on CTM. Therefore, we evaluated morphological patterns of the AMF on CTM and investigated the significance and mechanisms of contrast dye flow into the AMF. MethodsMorphological patterns of the AMF on CTM were examined in 79 patients. Group A (24 patients) underwent surgery because of symptomatic cervical myelopathy. Group B (43 patients) had no clinical symptoms but showed spinal cord compression on CTM. Group C (12 patients), who showed neither clinical symptoms nor cord changes, underwent CTM for lumbar lesion evaluation. AMF patterns were classified into 4 types according to their configurations on CTM (reversed T, Y, V, and O types). ResultsIn group B, the reversed T type and Y type appeared significantly more often near the compressed portion (p<0.001). A similar tendency was seen in group A. The V and O types were most frequently observed in group C (p<0.001). ConclusionOn CTM, contrast dye tends to flow into the AMF of the cervical cord when the spinal cord is compressed. We speculate that there may be 3 possible mechanisms for this phenomenon: deformation of the epipial layer of the AMF due to cervical cord compression, AMF dilatation due to atrophy of the anterior funiculus or anterior horn, and temporary AMF dilatation when it becomes an alternative route for cerebrospinal fluid circulation.

Schematic diagram of the neural protective role of IMMH004 after TGCI/R Pharmacological Induction of Mitochondrial Biogenesis using the β2‐Adrenoreceptor Agonist Formoterol for the Treatment of Spinal Cord Injury

A hallmark of the progressive cascade of damage referred to as secondary spinal cord injury (SCI) is vascular disruption resulting in ischemia and decreased oxygen delivery, which directly reduces the ability of mitochondria to maintain homeostasis. This leads to loss of ATP‐dependent cellular functions, Ca2+ overload, excitotoxicity and oxidative stress, further exacerbating injury. While therapeutics targeting restoration of single facets of mitochondrial function have proven largely ineffective post‐SCI, comprehensively addressing mitochondrial dysfunction via pharmacological stimulation of mitochondrial biogenesis (MB) is an underexplored strategy. The FDA‐approved, highly selective and potent β2‐adrenoreceptor (ADRB2) agonist formoterol is an effective inducer of MB in multiple organ systems in mice, including the spinal cord, as evidenced by increased mitochondrial DNA content and PGC‐1α expression. This study examined the effects of formoterol‐induced MB on recovery from SCI using a force‐controlled pneumatic impactor‐induced contusion model. Female C57bl/6 mice were subjected to moderate SCI (80 Kdyn) followed by daily formoterol administration (0.1 mg/kg, i.p) beginning 1 or 8 h post‐injury and continuing until euthanasia. SCI resulted in decreased mitochondrial protein expression, including PGC‐1α, in the injury and peri‐injury sites as early as 3 d after injury. Formoterol treatment attenuated this early decrease in PGC‐1α and restored downstream mitochondrial proteins to levels similar to that of sham controls by 15 d post‐SCI. Formoterol‐treated mice also exhibited less histological damage than vehicle‐treated mice 3 d after injury, namely reduced loss of white matter and structural preservation of the central canal and anterior median fissure. Importantly, as measured by the Basso‐Mouse Scale, the locomotor ability of formoterol‐treated injured mice reached twice that of vehicle‐treated SCI mice by 15 d (4.5 v 2), depicting nearly 50% recovery. Interestingly, a comparable degree of functional recovery was observed when formoterol treatment initiation was delayed until 8 h post‐SCI. These data provide evidence of ADRB2‐mediated MB as a therapeutic avenue for the treatment of SCI.Support or Funding InformationNational Institutes of Health National Institute of General Medical Sciences, Biomedical Laboratory Research and Development Program of the Department of Veterans Affairs, South Carolina Spinal Cord Injury Research FundThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Spectrum of Spinal Cord, Spinal Root, and Brain MRI Abnormalities in Congenital Zika Syndrome with and without Arthrogryposis.

Arthrogryposis is among the malformations of congenital Zika syndrome. Similar to the brain, there might exist a spectrum of spinal cord abnormalities. The purpose of this study was to explore and describe in detail the MR imaging features found in the spinal cords, nerve roots, and brains of children with congenital Zika syndrome with and without arthrogryposis. Twelve infants with congenital Zika syndrome (4 with arthrogryposis and 8 without) who had undergone brain and spinal cord MR imaging were retrospectively selected. Qualitative and quantitative analyses were performed and compared between groups. At visual inspection, both groups showed reduced thoracic spinal cord thickness: 75% (6/8) of the group without arthrogryposis and 100% (4/4) of the arthrogryposis group. However, the latter had the entire spinal cord reduced and more severely reduced conus medullaris anterior roots (respectively, P = .002 and .007). Quantitative differences were found for conus medullaris base and cervical and lumbar intumescences diameters (respectively, P = .008, .048, .008), with more prominent reduction in arthrogryposis. Periventricular calcifications were more frequent in infants with arthrogryposis (P = .018). Most infants had some degree of spinal cord thickness reduction, predominant in the thoracic segment (without arthrogryposis) or in the entire spinal cord (with arthrogryposis). The conus medullaris anterior roots were reduced in both groups (thinner in arthrogryposis). A prominent anterior median fissure of the spinal cord was absent in infants without arthrogryposis. Brain stem hypoplasia was present in all infants with arthrogryposis, periventricular calcifications, in the majority, and polymicrogyria was absent.

Fluid-Signal Structures in the Cervical Spinal Cord on MRI: Anterior Median Fissure versus Central Canal.

Hyperintense fluid-signal anterior median fissure and hyperintense foci resembling the central canal are seen on cervical spine axial T2 MR imaging. They may also be associated with a channel-like T2-hyperintense craniocaudad line on sagittal images. We hypothesized that the hyperintense foci and the sagittal line may represent the base of the anterior median fissure. In this exploratory study, 358 cervical MR images were analyzed for recording and comparing the incidence/numbers of hyperintense foci, anterior median fissure, and sagittal line as hyperintense foci, anterior median fissure, and sagittal line per patient when present alone or together, both with and without the sagittal line. Hyperintense foci were identified on 238/358 (66.5%) studies; an anterior median fissure, on 218/358 (60.9%). The hyperintense foci/anterior median fissure ratio was 3.7/2.3 (P = .00001). Anterior median fissures were seen alone less commonly than hyperintense foci were seen alone (P = .045). We identified increased anterior median fissure/patient in a hyperintense foci +anterior median fissure group compared with an anterior median fissure-only group (4.0 versus 3.2, P = .05), with similar hyperintense foci/patient in the hyperintense foci+anterior median fissure and hyperintense foci-only groups (5.5 versus 5.8, P = .35), and proportional distribution of both across the hyperintense foci+anterior median fissure subgroups (hyperintense foci/anterior median fissure ratio, 1.3). The sagittal line in 89 (24.9%) patients was associated with increased hyperintense foci and anterior median fissure/patient. Greater correlation of anterior median fissure/patient to sagittal line presence was seen in sagittal line subgroup analysis. This exploratory analysis found an increased anterior median fissure per patient in conjunction with hyperintense foci presence, a proportional increase of both across the hyperintense foci+anterior median fissure group, and greater correlation of anterior median fissure per patient with the sagittal line. These findings suggest that anterior median fissure and hyperintense foci are structurally related, that hyperintense foci may commonly be the base of the anterior median fissure, and that the sagittal line is a manifestation primarily of an anterior median fissure, occasionally appearing as channels that may simulate the central canal.

Poro-elastic modeling of Syringomyelia – a systematic study of the effects of pia mater, central canal, median fissure, white and gray matter on pressure wave propagation and fluid movement within the cervical spinal cord

Syringomyelia, fluid-filled cavities within the spinal cord, occurs frequently in association with a Chiari I malformation and produces some of its most severe neurological symptoms. The exact mechanism causing syringomyelia remains unknown. Since syringomyelia occurs frequently in association with obstructed cerebrospinal fluid (CSF) flow, it has been hypothesized that syrinx formation is mechanically driven. In this study we model the spinal cord tissue either as a poro-elastic medium or as a solid linear elastic medium, and simulate the propagation of pressure waves through an anatomically plausible 3D geometry, with boundary conditions based on in vivo CSF pressure measurements. Then various anatomic and tissue properties are modified, resulting in a total of 11 variations of the model that are compared. The results show that an open segment of the central canal and a stiff pia (relative to the cord) both increase the radial pressure gradients and enhance interstitial fluid flow in the central canal. The anterior median fissure, anisotropic permeability of the white matter, and Poisson ratio play minor roles.

Abbreviated exposure to hypoxia is sufficient to induce CNS dysmyelination, modulate spinal motor neuron composition, and impair motor development in neonatal mice.

Neonatal white matter injury (nWMI) is an increasingly common cause of cerebral palsy that results predominantly from hypoxic injury to progenitor cells including those of the oligodendrocyte lineage. Existing mouse models of nWMI utilize prolonged periods of hypoxia during the neonatal period, require complex cross-fostering and exhibit poor growth and high mortality rates. Abnormal CNS myelin composition serves as the major explanation for persistent neuro-motor deficits. Here we developed a simplified model of nWMI with low mortality rates and improved growth without cross-fostering. Neonatal mice are exposed to low oxygen from postnatal day (P) 3 to P7, which roughly corresponds to the period of human brain development between gestational weeks 32 and 36. CNS hypomyelination is detectable for 2–3 weeks post injury and strongly correlates with levels of body and brain weight loss. Immediately following hypoxia treatment, cell death was evident in multiple brain regions, most notably in superficial and deep cortical layers as well as the subventricular zone progenitor compartment. PDGFαR, Nkx2.2, and Olig2 positive oligodendrocyte progenitor cell were significantly reduced until postnatal day 27. In addition to CNS dysmyelination we identified a novel pathological marker for adult hypoxic animals that strongly correlates with life-long neuro-motor deficits. Mice reared under hypoxia reveal an abnormal spinal neuron composition with increased small and medium diameter axons and decreased large diameter axons in thoracic lateral and anterior funiculi. Differences were particularly pronounced in white matter motor tracts left and right of the anterior median fissure. Our findings suggest that 4 days of exposure to hypoxia are sufficient to induce experimental nWMI in CD1 mice, thus providing a model to test new therapeutics. Pathological hallmarks of this model include early cell death, decreased OPCs and hypomyelination in early postnatal life, followed by dysmyelination, abnormal spinal neuron composition, and neuro-motor deficits in adulthood.

PERK Activation Preserves the Viability and Function of Remyelinating Oligodendrocytes in Immune-Mediated Demyelinating Diseases

Remyelination occurs in multiple sclerosis (MS) lesions but is generally considered to be insufficient. One of the major challenges in MS research is to understand the causes of remyelination failure and to identify therapeutic targets that promote remyelination. Activation of pancreatic endoplasmic reticulum kinase (PERK) signaling in response to endoplasmic reticulum stress modulates cell viability and function under stressful conditions. There is evidence that PERK is activated in remyelinating oligodendrocytes in demyelinated lesions in both MS and its animal model, experimental autoimmune encephalomyelitis (EAE). In this study, we sought to determine the role of PERK signaling in remyelinating oligodendrocytes in MS and EAE using transgenic mice that allow temporally controlled activation of PERK signaling specifically in oligodendrocytes. We demonstrated that persistent PERK activation was not deleterious to myelinating oligodendrocytes in young, developing mice or to remyelinating oligodendrocytes in cuprizone-induced demyelinated lesions. We found that enhancing PERK activation, specifically in (re)myelinating oligodendrocytes, protected the cells and myelin against the detrimental effects of interferon-γ, a key proinflammatory cytokine in MS and EAE. More important, we showed that enhancing PERK activation in remyelinating oligodendrocytes at the recovery stage of EAE promoted cell survival and remyelination in EAE demyelinated lesions. Thus, our data provide direct evidence that PERK activation cell-autonomously enhances the survival and preserves function of remyelinating oligodendrocytes in immune-mediated demyelinating diseases.

Pathological examination of spinal lesions in meningeal carcinomatosis

For elucidation of the mechanism of spinal cord disorders associated with meningeal carcinomatosis, we investigated meningeal infiltration and parenchymal, vascular, and radicular damage in spinal cords subjected to pathological autopsy. Spinal cords were collected from 24 patients with a histopathological diagnosis of meningeal carcinomatosis. Infiltration from the subarachnoid space into the spinal cord occurred primarily along the perivascular tissue, and infiltration from the anterior median fissure to the anterior horn was found along the central artery in cases of marked meningeal dissemination. Meningeal dissemination was particularly evident with small cell carcinoma of lung, breast cancer and melanoma, and direct infiltration from the meninges into the spinal cord was found. Direct infiltration into the nerve roots was frequently observed, and infiltration was more evident in the dorsal roots than in the ventral roots, with loss of nerve fibers. Circular necrosis of the white matter in the periphery of the spinal cord was noted in cases of marked meningeal dissemination, which probably resulted from circulatory disturbance secondary to tumor infiltration. In cases of marked dorsal radiculopathy, there was secondary ascending degeneration of the posterior funiculus in cases of marked dorsal radiculopathy. These pathological changes associated with spinal cord disorders are important findings in reviewing spinal cord symptoms and radiographic findings in meningeal carcinomatosis.

The microvasculature of the spinal cord in the human adult

The microvasculature of the human spinal cord have been studied with scanning electron microscopy (SEM) on the corrosion casts of blood vessels, and light microscopy on the transparent after intra‐arterial injection of Indian ink and vascular staining specimens.On the surface of the cord, the density of the pial venous plexus was higher than the pial arterial plexus. The anterior spinal artery and vein gave off central arteries and veins, which ran posteriorly within the anterior median fissure. The number of the central arteries and veins per centimeter in length is highest in the lumbosacral cord, followed by the cervical and then the thoracic cord. In this study, the central arteries and veins were classified into types; type 1 dominated the arterial system and type 2 the venous system. The central arteries and veins sent long branches both rostrally and caudally along the axis of spinal cord. The order of their length was as follows: thoracic, cervical, lumbar and sacral cord. These blood vessels overlapped each other. The peripheral arteries terminated in the periphery of the gray matter while the peripheral veins originated within the different depth of the gray matter. The posterior spinal artery supplied the posterior horn and the substantia gelatinosa. The posteromedial veins arose in the deep posterior horns and posterior funiculus, and were occasionally connected with the anterior spinal vein within the cord. Overlapped zone which was supplied by both the central and peripheral vascular system was seen within the cord, and its extent was variable at different levels. The overlapped zone of the venous supply was broader than the arterial one. The peripheral veins appeared to drain blood not only from the white matter but also from the gray matter. The distribution of the capillary networks in the gray matter was slightly denser and showed more horizontal arrangement in the lumbosacral cord, and more sparse and longitudinal in the cervicothoracic cord. The distribution of the capillary networks in the white matter was parallel to nerve fibers which run longitudinal in the whole cord.Based on the result of present study, it was considered that the circulatory disturbances are prone to occur in the thoracic cord, and the circulatory block in the arterial system of the cord tends to cause a lesion in the gray matter, whereas the circulatory disturbances in the venous system tends to cause a lesion in the white matter.

MR imaging of abnormally rotated medulla oblongata, and a criterion for assessment of its normal orientation

In the MR imaging study of a 4-yr-old patient the medulla oblongata was detected to be rotated 25 degrees counter-clockwise with respect to the remainder of the brain and skull. A similar condition was not visually detected in the evaluation of consecutive 1100 CT and 500 MR imaging studies. The orientation of the medulla oblongata was then geometrically assessed on selected, axial inversion recovery MR images in a series of 50 normal pediatric patients. It was detected that in 70% of cases (n = 35) a line connecting the anterior median fissure and the posterior median sulcus of the medulla oblongata (interfissural line) was parallel to or blended with a vertical reference line passing through the third ventricle (midplane axis). In 30% of cases (n = 15) the interfissural line deviated from the midplane axis up to 10 degrees. It appears that deviation of the medulla oblongata to this extent should be considered to be within normal limits.