1. Presenter : Dr. Charusmita ChaudharyModerator: Dr R. K. Gogoi

2. In the spine, the most common congenital lesionspresenting to medical attention are the diverse forms of spinal dysraphism diverse forms of caudal spinal anomalies:diagnosed:::: Prenatally at birth in early childhood in adulthood 3. Techniques of imaging Radiography Computed Tomography Magnetic Resonance Imaging Ultrasonography Nuclear Imaging 4. EtiologyMultifactorial genetic, environmental influences,folic acid deficiency in the mothers.Ultrasonography is performed in high-riskpregnancies. 5. Categories Spina bifida aperta(myelocele and myelomeningocele)Occult spinaldysraphism Caudal spinal anomalies 6. Spinal Cord Development can be summarized in three basic embryologic stages1. The first stage : Gastrulation (the 2 or 3 week) conversion of the embryonic disk from a bilaminar disk to a trilaminar disk.1. The second stage : primary neurulation (weeks 34) the notochord and overlying ectoderm interact to form the neural plate. The neural plate bends and folds to form the neural tube, which then closes bidirectional in a zipperlike manner2. The final stage : secondary neurulation (weeks 56), a secondary neural tube is formed by the caudal cell mass. The secondary neural tube is initially solid and subsequently cavitation, eventually forming the tip of the conus medullaris and filum terminale by a process called retrogressive differentiation. Abnormalities at steps can lead to spine or spinal cord malformationsthe cephalic and caudal portions of the spinal cord form by distinctlydifferent mechanisms, they exhibit distinctly different types ofmalformation 7. Gastrulation. a Dorsal view and btransverse view of thebilaminar embryonic disk. Firstingressing cells at Hensens nodemove anterior to form headprocesses and notochord. Cellsingressingthrough primitive streak migrateventrally and laterally to formmesodermal a and endodermalprecursors 8. NEURULATION AND DERANGEMENTS OF NEURULATION four stages of neurulation Formation Shaping of Bending of of the the Neural the Neural Fusion Neural PlatePlatePlate 9. Primary neurulation. Formation of the Neural Plate Shaping of the Neural PlateBending of the Neural PlateFusionIllustrations of primary neurulation.Notochord (circle) interacts with overlyingectoderm to form neural plate (dark green),which then bends to form neural tube thatultimately closes in zipperlike fashion 10. Canalization and retrogressivedifferentiation (synonym: secondaryneurulation). Diagrammatic representationof proposed embryogenesis. 11. VASCULAR ANATOMY 12. Categorization of Spinal Dysraphisms Spinal dysraphismsopen and closed types In an open spinal dysraphismthere is a defect in the overlying skin, and the neural tissue is exposed to the environment. In a closed spinal dysraphism, the neural tissue is covered by skin. Closed spinal dysraphisms can be further subcategorized on the basis of the presence or absence of a subcutaneous mass. 13. Classification of spinal dysraphisms 14. Open spinal dysraphism (OSD; characterized byexposure of nervous tissue through a congenital Defect Almost 99% are myelomeningoceles Variable degree of sensorimotor deficits,bowel andbladder dysfunction All patients with OSD have Chiari II Role of MRI: anatomic characterization;presurgicalevaluation; identification of cord splitting whenpresent 15. Deranged Neurulation Spina Bifida Aperta: Myelocele andMyelomeningocele spina bifida aperta designates those forms of spinaldysraphism in which the neural tissue and/or meningesare exposed to the environment because the skin,fascia, muscle, and bone are deficient in the midline ofthe back 16. Open Spinal Dysraphisms Myelomeningocele andHemimyelomeningocele and myelocele hemimyelocele Myelomeningoceles andmyeloceles are caused by defectiveclosure of the primary neural tube Hemimyelomeningoceles and hemimyeloceles can also Exposure of the neural placodethrough a midline skin defect on occur but are extremely rare .the back.These conditions occur when Myelomeningoceles account for a myelomeningocele ormore than 98% of open spinal myelocele is associated withdysraphismsdiastematomyelia (cord Myeloceles are rare. splitting) and one hemicord fails to neurulate. 17. Open spinal dysraphisms are often diagnosedclinically, so imaging is not always performed. When imaging is performed,The main differentiating feature between amyelomeningocele and myelocele is the position ofthe neural placode relative to the skin surface The neural placode protrudes above the skin surfacewith a myelomeningocele and is flush with the skinsurface with a myelocele 18. Myelomeningocele. Axial schematic of Myelomeningocele. Axial T2-myelomeningocele shows neuralweighted MR image Myelomeningocele. Sagittal T2-placode (star) protruding above skin weighted MR image).surface due to expansion of underlyingsubarachnoid space (arrow). 19. Myelocele. Axial T2-weighted MRMyelocele. Axial schematic of myelocele image in 1-day-old girl shows exposedshows neural placode (arrow) flush with neural placode (arrow) that is flushskin surface. with skin surface, consistent withmyelocele. There is no expansion ofunderlying subarachnoid space 20. Antenatal ultrasonogram shows a lumbar meningocele. 21. Chiari Malformations 22. Chiari Malformations share common features, variable degree of reduction in size of the posteriorfossa and (with the exception of the type IV)herniation of portions of the cerebellum into theforamen magnum, it is accepted that type I (resultingfrom a mesodermal hindbrain abnormality) should beseparated from the other types that are related toneural tube closure defects 23. Chiari-I malformation Cerebellar tonsils >5 mm below basion-opisthionline or 35 mm and neurological signs or peg-like tonsils or syrinx 1456% neurologically normal Significant incidence of hydrosyringomyelia and/or hydrocephalus Caudal ectopia of the cerebellar tonsils into theforamen magnum is the hallmark of the Chiari-Imalformation 24. Axial T1-weighed image shows crowding of theforamen magnum due to the presence oftheSagittal T1-weighted image shows caudal tonsils (T) behind the medulla oblongatatonsillar ectopia (arrow).The posterior fossa is smallMultiple haustrations are a typical fi nding with Chiari-I-associated hydromeliaSagittal T1-weighted image 25. Chiari-II malformation Small posterior fossa Downward displacement of vermis, brainstem andfourth ventricle 90% has OSD Associated brain malformationsAntenatal ultrasonogram shows a lemon sign and a bananasign 26. Chiari II malformation with hydromyelia 27. Sagittal images very small posterior cranialfossa and the typical cascade of herniationsconstitutin the hallmark of the Chiari-IImalformation. 28. Diagrammatic representation of the spectrum of cervicomedullary deformitiesin the Chiari II malformation 29. Chiari II malformation as result of diversion of ventricular CSF to theamnion with collapse of the developing ventricular system The fluid-filled space of the developing brain and spinal cord iscalled the neurocele. The medial walls of the thoracic neural tube normally appose andocclude the neurocele transiently during central nervous system distal myelomeningocele fail to occlude the neurocele, even at sitesremote from the myelomeningocele. This failure to appose the walls appears to result from the samebiosynthetic defect in cell surface glycosaminoglycans that preventsthe neural tube from closing. the mechanism that causes failure of neurulation also causes failureof apposition of the medial walls of the neurocele. 30. theory proceeds as follows neurocele is not occluded, CSF passes freely down the central canal and out the myelomeningocele to the amnionic cavity This abnormal shunt collapses the developing primitive ventricular system.Therefore, the volume of the ventricular system and surrounding neural tissueis less than normal.The mesenchyme condenses in relation to an abnormally small volume of developing CNS. This establishes a smaller-than normal posterior fossa with low tentorium. The developing CNS must then grow within an envelope of membrane,cartilage, and bone that is too small for it. This leads to failure to form the pontine flexure, downward growth of thecervicomedullary junction, medulla, and cerebellum through the foramenmagnum, and upward growth of the cerebellum through the incisura. 31. 11. Reduced size of the third ventricle means closer approximation of thethalami with larger massa intermedia. Collapse of the cerebral ventricles leads to disorganization of the developinghemispheres with gray matter heterotopias,disorganization of cerebral gyri, anddysgenesis of the corpus callosumThe collapse of the ventricular system leads to disordered development of themembranous bone of the vault .Normally, the skull develops from centers ineach cranial plate. As the brain expands, the collagen bundles are drawn outfrom those centers in an orderly radial fashion, much like the uniformexpansion of the surface of an inflating balloon. As radial expansion proceeds,the collagen bundles become calcifiable and membranous bone forms. Lack of distension of the brain mass by increasing volumes of CSF producesdisordered arrays of collagen bundles. Thus, instead of radial lines of collagen,whorls and coils of collagen form with varying density between them.Ossification of this disorganized collagen mat then leads to lkenshdel 32. Chiari malformationChiari-III malformation Chiari-IV malformationChiari II + cephaloceleSevere cerebellar hypoplasia+ myelomeningocele 33. Closed Spinal Dysraphisms 34. Closed Spinal Dysraphisms With aSubcutaneous MassLipomas with a dural defectMeningocele Lipomas with a dural defect include both Herniation of a CSF-filled sac lined bylipomyeloceles and lipomyelomeningoceles.dura and arachnoid mater is referred to as a meningocele. The spinal cord is These abnormalities result from a defect in not located within a meningocele butprimary neurulation whereby mesenchymalmay be tethered to the neck of thetissue enters the neural tube and formsCSF-filled sac.lipomatous tissue 2 typescharacterized clinically by the presence of a Posterior meningoceles herniatesubcutaneous fatty mass above thethrough a posterior spina bifidaintergluteal crease. (osseous defect of posterior spinal The main differentiating feature between a elements) and are usually lumbar orlipomyelocele and lipomyelomeningocele issacral in location but also can occur inthe position of the placodelipoma interface the occipital and cervical regionsWith a lipomyelocele, the placodelipoma Anterior meningoceles are usually presacral in location but also caninterface lies within the spinal canal occur elsewhere With a lipomyelomeningocele, the placodelipoma interface lies outside of the spinalcanal due to expansion of the subarachnoidspace 35. Lipomyelocele. Axial T2-weighted MRimage shows placodelipoma interface Lipomyelocele. Sagittal T1-Lipomyelocele. Axial schematic ofweighted MR image(arrow) within spinal canal,lipomyelocele shows placodecharacteristic for lipomyelocele lipomyelocele showslipoma interface (arrow) liessubcutaneous fatty masswithin spinal canal(black arrow) and placode lipoma interface (white arrow) within spinal canal. 36. the hairy tuft overlyingsubcutaneous lipomas 37. Lipomyelomeningocele. Axialschematic oflipomyelomeningocele showsplacodelipoma interface(arrow) lies outside of spinalcanal due to expansion ofsubarachnoid space Lipomyelomeningocele. Axial T1-weighted MR image in 18-month-old boy shows lipomyelomeningocele (arrow) that is differentiated from lipomyelocele by location of placodelipoma interface outside of spinal canal due to expansion of subarachnoid space. 38. ,. B,. C., Sagittal T2-weightedSagittal T1-weighted MRSagittal T2-weighted MRMR image in 30-image shows posteriorimage shows largemonth-old girl showsherniation of CSF-filled sac posterior meningocelesmall posterior(arrow) in occipital region, (arrow) in cervical regionmeningocele (arrow) inconsistent with posteriorlumbar regionmeningocele 6Posterior meningoceleSagittal (A) and axial (B) T2-weighted MRimages in 6-month-old boy show small anteriormeningocele (arrows 39. Terminal myelocystocele Myelocystocele Herniation of large terminal A nonterminalsyrinx (syringocele) into amyelocystocele occursposterior meningocele through aposterior spinal defect is when a dilated centralreferred to as a terminal .canal herniates through a The terminal syrinx componentposterior spina bifidacommunicates with the centraldefect Myelocystoceles arecanal, and the meningocelecomponent communicates withcovered with skin and canthe subarachnoid space.occur anywhere but are The terminal syrinx andmost commonly seen inmeningocele components do notusually communicate with eachthe cervical orothercervicothoracic regions 40. SchematicTerminal myelocystocele.of nonterminalA, Sagittal schematic of terminal myelocystocele shows terminal myelocystocele showssyrinx (star) herniating into large posterior meningocele herniation of dilated(arrows). central canal throughB and C, Sagittal (B) and axial (C) T2-weighted MR images showposterior spinal defectterminal syrinx (white arrows) protruding through largeposterior spina bifida defect and herniating into posteriormeningocele component (black arrows). 41. Closed Spinal DysraphismsWithout a Subcutaneous MassSimple dysraphic states Complex dysraphic states Complex dysraphic states be intradural lipoma,divided into two categories: filar lipoma, A) disorders of midline tight filum terminale,notochordal integration,persistent terminal ventricle dorsal enteric fistula,neurenteric cyst, and dermal sinus.diastematomyelia, B)disorders of notochordalformation, caudal agenesis andsegmental spinal dysgenesis. 42. lipoma An intradural lipoma refers to a lipoma located along the dorsal midlinethat is contained within the dural sac No open spinal dysraphism is present commonly lumbosacral in location usually present with tethered-cord syndrome Fibrolipomatous thickening of the filum terminale is referred to as afilar lipoma.On imaging, a filar lipoma appears as a hyperintense strip of signal onT1-weighted MR images within a thickened filum terminale Filar lipomas can be considered a normal variant if there is no clinicalevidence of tethered-cord syndrometethered-cord syndrome a clinical syndrome ofprogressive neurologic abnormalities in the setting oftraction on a low-lying conus medullaris 43. Spinal lipomafocal premature disjunction of epidermalfrom neural ectoderm.curved arrows are also used toindicate the course of mesenchymemigrating through the focal disjunction tothe dorsal surface of the closing neural folds 44. Diagrammatic representations of spinal lipomas. A: Intradural lipoma. The laminae(L) are bifid. The dura (dark line) is intact. The pia-arachnoid (dashed line) enclosesthe spinal cord and the lipoma. The lipoma lies predominantly within a midline cleft inthe dorsal spinal cord but fungates beneath the pia to bulge into the dorsalsubarachnoid spaceD, dorsal root; V, ventral root; G, dorsal root ganglion. B: Lipomyelocele. There isposterior spina bifida with everted C: lipomyelomeningocele 45. Intradural lipoma Filar lipoma, Sagittal (A) and axial (B) T1-weighted MRimages I with filar lipoma (arrows),which has characteristic T1 hyperintensity andmarked thickening of filum terminale.Sagittal T1-weighted (A) and sagittal T2-weighted fat-saturated (B) MR images show largeintradural lipoma (arrows), which ishyperintense on T1-weighted image and hypointenseon T2-weighted fat-saturated image. Lipoma isattached to conus medullaris, which is low lying. 46. Intraspinal lipomas may produce posterior scalloping of vertebral bodies and flattening of the pedicles D/D intraspinal tumors; neurofibromatosis; acromegaly; achondroplasia; communicatingPlain radiographs show posterior scalloping. hydrocephalus; syringomyelia; and a number of congenital syndromes, including Ehlers- Danlos, Marfan, Hurler, Morquio, and osteogenesis imperfecta syndromes. 47. Simple dysraphic states TIGHT FILUM TERMINALETight filum terminale ischaracterized by hypertrophy andshortening of the filum terminale . This condition causes tethering ofthe spinal cord and impairedascent of the conus medullaris. The conus medullaris is low lyingrelative to its normal position,which is usually above the L2L3disk level fila thicker than 2 mm were abnormal. Sagittal T2-weighted MR image in 12-month-old boy shows tight filum terminale, characterized by thickening and shortening of filum terminale (black arrow) with low-lying conus medullaris. Incidental cross-fused renal ectopia (white arrow) is also present. 48. Left, plain radiograph of the lumbar spineLeft, anteroposterior (AP) plainradiograph of the lumbar spine shows shows bony defects in the laminae of L2 toa defect within the laminae of S1 and S1. Right, myelogram shows a split cord.Left plain anteroposterior (AP) radiograph of S2. Right, myelograms in the samethe lumbar spine shows spina bifida occulta.patient show a markedly thickened,Right, myelogram of the same patient shows a low tethered cordthick tethered cord 49. Simple dysraphic states TERMINAL VENTRICLE Persistence of a small, ependymallined cavity within the conusmedullaris is referred to as apersistent terminal ventricle . It appears to represent the point of unionbetween the portion of the central canalmade by neurulation and the portion madeby canalization of the caudal cell mass Key imaging features includelocation immediately above thefilum terminale and lack of contrastenhancement, which differentiatethis entity from other cystic lesionsPersistent terminal ventricle.of theconus medullaris A and B, Sagittal T2-weighted (A) and sagittal T1-weighted contrast-enhanced (B) MR images in 12-month-old boy show persistent terminal ventricle as cystic structure (arrows) at inferior aspect of conus medullaris, which does not enhanc 50. Simple dysraphic states Dermal sinus A dermal sinus is an epithelial linedfistula that connects neural tissueor meninges to the skin surface. If the superficial ectoderm fails toseparate from the neural ectodermat one point, lumbosacral region and is oftenassociated with a spinal dermoid atthe level of the cauda equina orconus medullaris Clinically, patients present with amidline dimple and may also havean associated hairy nevus,hyperpigmented patch, or capillaryhemangioma Surgical repair is of great importance because , Sagittal schematic (A) and sagittal T2-weighted MR image (B) inthe fistulous connection between neural tissueand the skin surface can result in infectious9-year-old girl show intradural dermoid (stars) with tractcomplications such as meningitis and abscess extending from central canal to skin surface (black arrows). Note tenting of dural sac at origin of dermal sinus (white arrows). C, Axial T2-weighted MR image from same patient as in B shows posterior location of hyperintense dermoid (arrow) 51. .Proposed embryogenesis of dorsal dermalsinus by incomplete disjunctionDorsal dermal sinus. Diagrammaticrepresentation 52. Complex dysraphic statesDISORDERS OF MIDLINE DISORDERS OFNOTOCHORDALNOTOCHORDAL FORMATIONINTEGRATION dorsal enteric fistula, caudal agenesis neurenteric cyst segmental spinal dysgenesis. diastematomyelia, 53. Disorders of midline notochordalintegration Dorsal enteric fistula and neurenteric cystA dorsal enteric fistula occurs when there is an abnormal connection between the skin surface and bowel.Persistence of a patent neurenteric canal (canal of KovalevskyNeurenteric cysts represent a more localized form of dorsal enteric fistula .These cysts are lined with mucin-secreting epithelium similar to the gastrointestinal tract and are typically located in the cervicothoracic spine anterior to the spinal cord 54. Split notochord syndrome. Diagrammaticrepresentation of developmental posteriorenteric remnants. 55. 5Neurenteric cyst in 3-year-old girlA and B, Sagittal T2-weighted (A) and axial T1-weighted (B)MR images show bilobed neurenteric cyst (arrows) extendingfrom central canal into posterior mediastinum.C, Three-dimensional CT reconstruction image shows osseousopening (arrow) through which neurenteric cyst passes. Thisopening is called the Kovalevsky canal 56. Disorders of midline notochordalintegration Diastematomyelia Separation of the spinal cord into two hemicords is referred to asdiastematomyelia. The two hemicords are usually symmetric, although the length ofseparation is variable. There are two types of diastematomyelia. In type 1Dual Dural-Arachnoid Tubes (Pang Type I), the twohemicords are located within individual dural tubes separated by anosseous or cartilaginous septumIn type 2, Single Dural-Arachnoid Tube (Pang Type II) there is asingle dural tube containing two hemicords, sometimes with anintervening fibrous septum Diastematomyelia can present clinically with scoliosis and tethered-cordsyndrome. A hairy tuft on the patients back can be a distinctive findingon physical examination 57. Embryogenesis of split notochord syndrome Posterior view of the patient reveals the large patch of long, silky hairs overlying stematomyelia and a small sacral dimple (arrow 58. Type 1 diastematomyeliaSagittal T2-weighted MR (A), axial T2-weighted MR (B), and axialCT with bone algorithm (C) images in 6-year-old boy show twodural tubes separated by osseous bridge (arrows), which ischaracteristic for type 1 diastematomyelia.Axial CT scans through theupper lumbar spine show asplit cordlumbosacral region; a long, tethered cord; anddiastematomyelia. 59. Type 2 diastematomyelia., Sagittal T1-weighted (A), coronal T1-weighted (B), and axial T2-weighted (C)MR images show splitting of distal cordinto two hemicords (white arrows, Band C) within single dural tube, whichis characteristic for type 2diastematomyelia. Incidental filumlipoma (black arrows, A and B) ispresent as well. 60. Disorders of notochordalformation: Caudal agenesis Caudal agenesis refers to total or partial agenesis of thespinal column and may be associated with thefollowing: anal imperforation, genital anomalies, renaldysplasia or aplasia, pulmonary hypoplasia, or limbabnormalities. 61. Caudal agenesisCaudal agenesis can be categorizedinto two types. In type 1, there is a high positionand abrupt termination of theconus medullaris. In type 2, there is a low positionand tethering of the conusmedullaris , Sagittal T2-weighted (A) and sagittal T1- weighted (B) MR images in show agenesis of sacrum. Conus medullaris is high in position and wedge shaped (arrow) due to abrupt termination. These findings are characteristic of type 1 caudal agenesis. Distal cord syrinx (arrowhead) is present as well. 62. Syndrome of Caudal Regression 63. Syndrome of Caudal Regression constellation of anomalies of the hind end of the trunk,including partial agenesis of the thoracolumbosacral spine,imperforate anus, malformed genitalia, bilateral renaldysplasia or aplasia, pulmonary hypoplasia, and, in themost severe deformities, extreme external rotation andfusion of the lower extremities (sirenomelia) Sacral agenesis arises early in gestation, probably before the10th week of gestation diabetes mellitus,OEIS complex, VATER syndrome (see later discussion), and congenital heart defects (24%); genitourinary complaintswith hydronephrosis, unilateral renal agenesis, pelvic andhorseshoe 64. Posterior view of the patient reveals theshort, shallow intergluteal cleftand poorlydeveloped gluteal musculature. 65. Classification of LumbosacralAgenesis I Total SA; some lumbar vertebrae also missingIWa Ilia articulate with sides of the lowest vertebra,maintaining relatively normal transverse pelvic diameter INa Ilia articulate or fused with each other below lastvertebra, severely shortening transverse pelvic diameter II Total SA; lumbar vertebrae not involvedIWa Ilia articulate with sides of L-5 vertebra maintainingrelatively normal transverse pelvic diameter INa Ilia articulate or fuse with each other below L-5vertebra, severely shortening transverse pelvic diameter III Subtotal SA; at least S-1 is present, sacrum lacks four, three, two, orone of its caudal segments, ilia articulate with sides of rudimentarysacrum, maintaining normal transverse pelvic diameter 66. IV HemisacrumIVA Total hemisacrum; all sacral segments presenton one side, but entire opposite side is missingIVB Subtotal hemisacrum, unilateral; all sacralsegments present on one side, only part of opposite side ismissing IVC Subtotal hemisacrum, bilateral; part of each sideis missing but to different extents V Coccygeal agenesisVA TotalVB Subtotal 67. Disorders of notochordal formation Segmental spinal dysgenesis The clinicalradiologic definition of segmental spinal dysgenesis includes several entities: segmental agenesis or dysgenesis of the thoracic or lumbar spine, segmental abnormality of the spinal cord or nerve roots, congenital paraparesis or paraplegia, and congenital lower limb deformities. Three-dimensional CT reconstruction image (A) in Three-dimensional CT4-year-old girl and schematic illustration (B) show multiple reconstructions can besegmentation anomalies in lumbar spine (superior to helpful in showing variousinferior beginning at level of arrow): partial sagittal partition, vertebral segmentationbutterfly vertebra, hemivertebra, tripedicular vertebra, anomalies and widely separated butterfly vertebra 68. Congenital Spine and Spinal Cord MalformationsPictorial Review 69. CONTENTS.. STAGES OF DEVELOPMENTOF VC formation of mesenchymal vc formation of cartilaginous vc ossification of vc 70. development begins during gastrulation when epiblastic cells migrate toward the cranial portion of the primitive streak, ingress through the primitive groove, and then migrate laterally as the prospective somitic mesoderm 71. stages Stage 1formation of mesenchymal vertebralcolumn : 4th week 1.Migration of sclerotomes. Differentiation ofsclerotomic segments Each segments differentiated intoCephalic part (lesscondensed)Caudal part (morecondensed) 72. 3. Development of intervertebraldiscs Densely packed cellmove cranially to themiddle part of eachsegments Form peripheral partannulus fibrosus Enclosed notochordexpands and undergomucoid degeneration Form central part nucleus pulposus 73. 4. Development of the body ofvertebrae Caudal remained part fusewith cephalic partadjacent to it to formmesenchymal centrum Notochord degeneratesand disappears whensurrounded by vertebralbody 74. 5. Development of neural arch Sclerotomic tissue migratebackward from both side ofcentrum and surroundneural tube. Neural spine forms atmeeting point of neuralarch Sclerotomic tissue alsoextends laterally from bothsides of centrum form 2processes Costal (ventral) Transverse (dorsal) 75. Stage 2Stage of formation of cartilaginous vertebral column 6th week 2 centers of chondrification in each Centrum appear Fuse together at the end of embryonic period (8th week) form cartilaginous centrum Centers of chondrification appear in neural arhes and fuse with each other and centrum Chondrification spreads until a cartilaginous vertebral column formed 76. Stages of ossification Comprises of 2 stages: 1. primary ossification center 2. secondary ossification center Primary ossification center at the end of 8th week. 3 ossification centers are present by the end ofembryonic period one in the centrum one in the neural arch 77. Process: bony halves of the vertebral arch fuse together duringthe first 3 to 5 years the arches articulate with the centrum at cartilaginousneurocentral joints these joints dissapear when vertebral arches fuses withthe centrum during the 3rd to 6th years 78. Secondary ossification center Time of development: after pubertythe 5 secondary ossification center appears at, 1. tip of spinous process 2. tip of each transverse process 3. superior rim of the vertebral body 4. inferior rim of the vertebral body 79. Fate of notochord Cranial part: merged with basilar part of occipital bone& posterior part of body of sphenoid Notochord located in the vertebra undergodegeneration and disappear The ones located in between undergo mucoiddegeneration to form nucleus pulposus 80. Fate of the costal process Costal process results from ventrolateral outgrowth ofthe caudal, denser half of a sclerotome. In the cervical region: form anterior and lateralboundary of the foramen transversum In the thoracic region: form the ribs In the lumbar region: fuse with the transverse process In the upper sacral region: they unite to form theanterior portion of the ala of sacrum 81. Spina bifidaCause: incomplete fusion ofhalves of the vertebral archesresulting in midline defectusually in lumbosacralregionFeature: It varies, butgenerally the small bones(vertebrae) that make up thespine dont form fully andmay have gaps betweenthem. 82. Congenital Spinal Deformity caused by anomalous vertebral development in theembryo simple and benign, causing no spinal deformity, or theymay be complex, producing severe spinal deformity oreven cor pulmonale or paraplegia. 83. patterns Hyperlordosis Kyphosis scoliosis 84. On basic developmental pathogenesis,divided into the following 3 categories: Malformation a failure of the embryologic differentiationand/or development of a specific anatomic structure,causing it to be absent or improperly formed before thefetal period commences formation of a hemivertebra. Disruption destruction of an anatomic feature that formednormally during the embryonic period. This phenomenon,resulting in a structural defect, limb. Deformation an alteration in the shape or structure of anindividual vertebra or of the entire spine during the fetaland/or postnatal periods, after the involved regions initial,normal differentiation 85. Defects of formation may beclassified as follows: Anterior formation failure - This results in kyphosis,which is sharply angulated. Posterior formation failure - This is rare but canproduce a lordotic curve. Lateral formation failure - This occurs frequently andproduces the classic hemivertebrae of congenitalscoliosis 86. Schematic drawing depicting thedevelopment ofnormal and abnormal vertebral bodies 87. Vertebral Body ConfigurationsCongenital B. Hemivertebra Asomia (A genesis) Unilateral wedge vertebra is due to lack of ossification of one-half of the body apex of the wedge reaching the midplane Scoliosis is often present 88. Metametric hemivertebrae in the lowerDorsal hemivertebra involving Li lumbar spine with mermaid deformity of the lower extremities 89. Metametric hemivertebrae in the lowerDorsal hemivertebra involving Li lumbar spine with mermaid deformity of the lower extremities 90. Butterfly vertebra involving L4Vertebrae with coronal clefts. 91. (A) Block vertebra with congenital fusion ofC4 andCS Note the presence of a waist at the site offusion (arrow). (B) Acquired vertebral body fusionof CS and C6. 92. HemivertebraCause: failure of one of thechondrofication center to appearand subsequent failure of half ofvertebra to formFeature: defective vertebra producescoliosis ( lateral curvature)Most likely to cause neurologicproblems 93. Sacralization of 5th lumbar vertebra Cause: 5th lumbar is fused with the sacrum Feature: number of lumbar vertebra is 4 and the sacrum is formed of 6 vertebra 94. Lumbrization of first piece ofsacrum to form separate vertebra Cause: separation of first piece of sacrum to form separate vertebra Feature: number of lumbar vertebra is 6 and the sacrum is only formed of 4 sacral vertebra 95. Congenital Kyphosis Two types of congenital kyphosis exist:defects of segmentationdefects of formation Defects of segmentation occur most often inmidthoracic or thoracolumbar regions and may involve2-8 levels . produce a round kyphosis 96. Congenital kyphosis 97. Congenital Scoliosis lateral curvature of the spine that is caused bycongenital anomalies of vertebral developmentclassified according to the types of anomalies. Failure of formation Partial failure of formation (wedge vertebra) Complete failure of formation (hemivertebra) 98. Failure of segmentation (see image below)Unilateral failure of segmentation(unilateral unsegmented bar)Bilateral failure of segmentation (blockvertebra)Mixed (see image below) 99. Congenital scoliosis 100. Congenital Lordosis least common of the 3 major patterns of congenitalspinal deformity caused by a failure of posterior segmentation in thepresence of anterior active growth usually is progressive Treatment of congenital lordosis is purely surgical. 101. We can summarize above notes as follows: 1.The vertebra is intersegmental structure made up fromportions of two somites the position of the somite isrepresented by intervertebral disc. 2.The transverse processes and the ribs areintersegmental structures. They separate the musclesderived from two adjoining myotomes. 3.Spinal nerves are segmental structures. They emergefrom between two adjacent vertebrae and lie betweentwo adjacent ribs. 4.The blood vessels supplying the structures derivedfrom the myotome are intersegmental like vertebrae.Therefore the intercostal and lumbar arteries lieopposite the vertebral bodies 102. Imaging of the bony spine requires methods different from those used toimage the spinal canal and its contents. Age influence the choice of modality The best way to image skeletal anomalies : plain radiography combinedwith conventional tomography Spinal malformations :best performed by MRI Skeletal scintigraphy with technetium-99m diphosphonates has highsensitivity but low specificity In the evaluation of the spinal canal, ultrasonography is limited to theneonatal period, though a spinal defect covered with soft tissue may beimaged well into adult life Fetal ultrasonography is increasingly used as a primary screening tool forNTDs, usually at about 18 weeks gestational age 103. Limitations of techniques X ray : Radiation delivers a high dose : gonads, particularly in female patients. Ultrasonography remains operator dependent; depends on theskill and experience and on the quality of the equipment. Transaxial CT images may be difficult to interpret because of thecomplex anatomy of the vertebral bodies, the presence ofsegmentation anomalies, and the presence of spinal curvatureabnormalities. , in as much as sagittal and coronalreconstruction now provide exquisite images of the spine. In parts of the developing world, MRI is not readily available In addition, use of MRI may not be possible in patients withclaustrophobia, and it is contraindicated for some patients withimplanted devicesChildren may require sedation. 104. Special concerns Neural tube defects (NTDs) exact emotional and economic toll on families and health care systemsThe tragedy is that NTDs are preventable simply by having women take a folic acid supplement during the 2 months before they become pregnant. 0.4 mg daily before conception and for the first 3 months of pregnancy, reduces the risk of having a baby with spina bifida. risk(4 mg) of folic acid. 105. SUMMARY Spinal dysraphism, or neural tube defect (NTD), is a broad termencompassing a heterogeneous group of congenital spinal anomalies,which result from defective closure of the neural tube early in fetal lifeand anomalous development of the caudal cell mass. can cause progressive neurologic deterioration. The anatomic features common to the entire group is an anomaly in themidline structures of the back, especially the absence of some of theneural arches, and defects of the skin, filum terminale, nerves, andspinal cord. classified as closed forms or open forms, open forms are often associated with hydrocephalus and Arnold-chiarimalformation type II Spina bifida is described in the medieval literature, although thecondition was recognized even earlier. Indeed, the association of footdeformities with lumbar or lumbosacral hypertrichosis may be the originof the mythological figure of the satyr. 106. Spina bifida occulta is characterized by variable absence ofseveral neural arches and various cutaneousabnormalities, such as lipoma, hemangioma, cutis aplasia, dermal sinus,or hairy patch, and it is often associated with a low-lyingconus Whenever the conus lies below the L2-3 interspace in aninfant, cord tethering should be considered. Patients with spina bifida occulta may present withscoliosis in later years. Approximately 95% of couples that have a fetus affectedwith ONTD have a negative family history. 107. THANK YOUFOLIC ACIDIMAGING OF CONGENITAL ANOMALIES OFSPINE AND SPINAL CORD