congenital diseases of the spine
TRANSCRIPT
SpineCongenital Diseases
Mohamed Zaitoun
Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals
EgyptFINR (Fellowship of Interventional
Neuroradiology)[email protected]
Knowing as much as possible about your enemy precedes successful battle
and learning about the disease process precedes successful management
Congenital Diseases of the Spine1-Spinal Dysraphism2-Congenital Spinal Stenosis3-Scoliosis4-Tethered Cord Syndrome5-Syringohydromyelia6-Spinal Cord Herniation7-Neurofibromatosis8-Klippel-Feil Syndrome9-Achondroplasia
1-Spinal Dysraphism :-A group of spinal anomalies involving incomplete
midline closure of bone and neural and soft tissues (known as neural tube defects)
-Classified into :1-Open Spinal Dysraphism (Spina Bifida Aperta)2-Closed (Spina Bifida Occulta) Spinal
Dysraphisms With a Subcutaneous Mass3-Closed (Spina Bifida Occulta) Spinal
Dysraphisms Without a Subcutaneous Mass
*Embryology :-The human nervous system develops from a small
specialized plate of cells along the back of an embryo-Early in development , the edges of this plate being to curl
up toward each other creating the neural tube (a narrow sheath that closes to form the brain and spinal cord of the embryo)
-As development progresses , the top of the tube becomes the brain and the remainder becomes the spinal cord , the process is usually complete by the 28th day of pregnancy
-But if problems occur during this process , the result can be brain disorders called neural tube defects , including spina bifida
-Spina bifida, which literally means (split spine) is characterized by the incomplete development of the brain, spinal cord and/or meninges, it is the most common neural tube defect
-the lumbo-sacral region is the commonest (90%)-Ultrasound generally has a high detection rate for
spina bifida and may show dorsal ossification centers / lateral pedicles as being splayed apart (which can give a V shaped appearance to the posterior elements)
Aperta Occulta with s.c. mass Occulta without s.c. mass
Spina bifida occulta
1-Open Spinal Dysraphism (Spina Bifida Aperta):-85 %-Defective closure of the primary neural tube and
are characterized clinically by exposure of the neural placode through a midline skin defect on the back (the malformation is exposed to air)
-They are :a) Myelomeningoceleb) Myelocelec) Hemimyelomeningocele & Hemimyelocele
a) Myelomeningocele :-Protruding placode, almost 100% association with
Chiari II-Contains neural tissue within the expanded
posterior subarachnoid space with cord tethering
-Accounts for more than 98% of open spinal dysraphisms
-More in the lumbosacral region
Myelomeningocele : Low back of 1-hour-old newborn prior to surgery, the placode (P) is directly exposed to the environment and is surrounded by partially epithelized skin (membrano-epithelial zone) (asterisk) , more laterally , intact skin (S) is elevated by underlying expanded subarachnoid spaces
(A) Myelomeningocele , Axial schematic of myelomeningocele shows neural placode (star) protruding above skin surface due to expansion of underlying subarachnoid space (arrow)
(B) Myelomeningocele , Axial T2 in 1-day-old boy shows neural placode (black arrow) extending above skin surface due to expansion of underlying subarachnoid space (white arrow) which is characteristic of myelomeningocele
Myelomeningocele, 8-hour-old male newborn. A. Sagittal T1 of the lumbosacral spine shows the spinal cord (white arrowheads) crosses the meningeal outpouching and ends with an exposed terminal apical placode (P) , notice dehiscent subcutaneous fat (asterisks). B. Sagittal T1 of the brain shows Chiari II malformation with hydrocephalus
Sagittal T2 shows neural placode (white arrow) protruding above the skin surface due to the expansion of underlying subarachnoid space (black arrow)
Sagittal T2 shows a dorsal mid line fusion defect in lumbo sacral region , herniation of meningeal sac out the defect forming a subcutaneous swelling , low lying tethered cord with neural elements noted traversing the meningeal sac , focal dilatation of central canal of cord
b) Myelocele :-Rare-The placode is flush with the skin-The subarachnoid space isn’t dilated
(A) Myelocele , Axial schematic of myelocele shows neural placode (arrow) flush with skin surface
(B) Myelocele , Axial T2 in 1-day-old girl shows exposed neural placode (arrow) that is flush with skin surface , consistent with myelocele , there is no expansion of underlying subarachnoid space
Myelocele, 12-hour-old newborn. Sagittal T1 shows exposed , slightly funnel-shaped placode (P) lying flush with the skin surface , there is dehiscence of subcutaneous fat (asterisks) , the lack of expansion of subarachnoid spaces is the only difference from the much more common myelomeningocele
c) Hemimyelomeningocele & Hemimyelocele :-Extremely rare-Myelomeningoceles and myeloceles are
associated with diastematomyelia in 8-45% of cases
-Only when one hemicord fails to neurulate is the malformation called hemimyelocele
-When there is associated meningeal expansion , the malformation is called hemimyelomeningocele
Axial fat suppressed T2 shows right hemicord (white arrow) separated by a bony spur (dashed arrow) from the left hemicord myelomeningocele (asterisk)
2-Closed Spinal Dysraphisms With a Subcutaneous Mass :
-There is an intact skina) Lipomas with a dural defectb) Meningocelec) Non-Terminal Myelocystoceled) Terminal Myelocystocele
a) Lipomas With a Dural Defect :-Lipomyelocele & Lipomyelomeningocele-Characterized by a midline subcutaneous fatty
mass right above the intergluteal crease, usually extending asymmetrically into one buttock
-There is a lipoma attached to the dorsal surface of the cord termination and intact skin overlying the defect, the lipoma extends through the dysraphic spinal canal merging with and becoming indistinguishable from the subcutaneous fat, the distal cord is tethered by the lipoma
-The main differentiating is the position of the placode-lipoma interface :
*Lipomyelocele :The placode-lipoma interface lies within or at
the edge of the spinal canal*Lipomyelomeningocele :The placode-lipoma interface lies outside of
the spinal cord, it lies due to expansion of the subarachnoid space
(A) Lipomyelocele , Axial schematic of lipomyelocele shows placode-lipoma interface (arrow) lies within spinal canal
(B) Lipomyelocele , Axial T2 in 3-year-old girl shows placode-lipoma interface (arrow) within spinal canal , characteristic for lipomyelocele
Sagittal T1 in 3-years-old girl with lipomyelocele shows subcutaneous fatty mass (black arrow) & placode-lipoma interface (white arrow) within the spinal canal
Lipomyelocele , 1-month-old girl. A. Sagittal T1 shows large subcutaneous lipoma with fatty tissue creeping through a wide posterior bony spina bifida into the spinal canal to connect with the placode (arrowheads) , although the size of the subcutaneous lipoma may not seem huge , the amount of fat is way too large for a newborn. Moreover , the mass is flattened as the child lies supine. B. Axial T1 shows the placode (P) , lipoma (L) interface into the spinal canal
(A) Lipomyelomeningocele , Axial schematic of lipomyelomeningocele shows placode-lipoma interface (arrow) lies outside of spinal canal due to expansion of subarachnoid space
(B) Lipomyelomeningocele , Axial T1 in 18-month-old boy shows lipomyelomeningocele (arrow) that is differentiated from lipomyelocele by location of placode-lipoma interface outside of spinal canal due to expansion of subarachnoid space
Lipomyelomeningocele, 1-year-old boy. A. Sagittal T1 shows large subcutaneous lipoma , the spinal cord exits the spinal canal through a posterior sacral spina bifida and ends into a terminal apical placode (P) that connects to the inner surface of the lipoma (black arrowheads) , notice concurrent hydromyelia (white arrows). B. Axial T1 shows terminal apical placode , expansion of the subarachnoid spaces causes the placode to bulge outside the anatomic boundaries of the spinal canal through a wide posterior spina bifida (white arrows) , the meningocele (M) develops symmetrically to both sides of the placode (P) , the placode-lipoma interface lies on the midline (black arrowheads)
Lipomyelomeningocele, 40-day-old girl. A. Sagittal T1 shows large meningocele (M) contained within a huge subcutaneous lipoma , the spinal cord (white arrow) is seen to approach the neck of the meningocele in this midsagittal view , notice the last visible vertebra is S2 , consistent with an associated picture of caudal agenesis. B. Axial T1 shows the spinal cord projects out of the spinal canal and courses along the left side of the meningocele (M) to connect to the lipoma (arrowhead): therefore, the placode (P) is terminal apical and the off-midline placode-lipoma interface lies outside the anatomic boundaries of the spinal canal, consistent with a diagnosis of lipomyelomeningocele
b) Meningocele :-Herniation of a CSF-filled sac lined by dura
and arachnoid mater, the spinal cord isn’t located within a meningocele but may be tethered to the neck of the CSF filled sac
1-Posterior Meningocele :-Herniates through a posterior spina bifida ,
commonly lumbar or sacral in location
Meningocele , 7-month-old girl. A,B. Sagittal T1 show large sacral cerebrospinal fluid-filled mass (M) , the overlying skin is continuous , the conus medullaris is low , C. T1 show associated lipomatous filum terminale (arrows)
Posterior meningocele , Sagittal T2 in 30-month-old girl shows small posterior meningocele (arrow) in lumbar region
Posterior meningocele , Sagittal T1 in 12-month-old girl shows posterior herniation of CSF-filled sac (arrow) in occipital region , consistent with posterior meningocele
Posterior meningocele , Sagittal T2 in 5-year-old boy shows large posterior meningocele (arrow) in cervical region
2-Anterior Sacral Meningocele :-Protrusion of the dura & leptomeninges anteriorly
through a defect in the sacrum, the neck of the lesion is typically narrowed
-Is usually presacral and consistently found within the setting of caudal agenesis
-It can occur as part of the Currarino triad-On sagittal CT or MRI or lateral plain films, the
residual sacrum will be scalloped anteriorly & beneath the defect (in a semicircular manner) leading to the appearance of a scimitar or sickle
-MRI : the contents will be isointense with CSF on all pulse sequences, it is important to delineate on imaging whether nerve roots traverse the sacral defect to lie within the meningeal sac which indicates simple ligation of the neck of the meningocele
Scimitar sacrum
Scimitar sacrum
T1 T2
T1 T2
*N.B. : Currarino triad (ASP triad)1-Anorectal malformation or congenital
anorectal stenosis2-Sacrococcygeal osseous defect 3-Presacral mass : anterior sacral
meningocele , tumors like teratoma & hamartoma
3-Lateral Thoracic Meningocele :-Appears as a paravertebral mass
c) Non-Terminal Myelocystocele :-Occurs when a dilated central canal
herniates through a posterior spina bifida defect
-Myelocystoceles are covered with skin and can occur anywhere but are most commonly seen in the cervical or cervicothoracic region
Schematic of non-terminal myelocystocele shows herniation of dilated central canal through posterior spinal defect
d) Terminal Myelocystocele :Herniation of large terminal syrinx (syringocele)
into a posterior meningocele through a posterior spinal defect is referred to as a terminal myelocystocele
-The terminal syrinx component communicates with the central canal and the meningocele component communicates with the subarachnoid space
-The terminal syrinx and meningocele components do not usually communicate with each other
Terminal myelocystocele , Sagittal schematic of terminal myelocystocele shows terminal syrinx (star) herniating into large posterior meningocele (arrows)
Terminal myelocystocele. Sagittal (A) and axial (B) T2 in 1-month-old girl show terminal syrinx (white arrows) protruding through large posterior spina bifida defect and herniating into posterior meningocele component (black arrows) , Sagittal image shows turbulent flow in more anterior meningocele component (star, A)
Arrows point to the deformed and displaced spinal cord M = meningocele , S = syringocele , Vb = vertebral body
3-Closed Spinal Dysraphisms Without a Subcutaneous Mass :
-There is an intact skina) Simple Dysraphic Statesb) Complex Dysraphic States
a) Simple Dysraphic States :-Consist of :1-Intradural Lipoma2-Filar Lipoma3-Tight Filum Terminale4-Persistent Terminal Ventricle5-Dermal Sinus
1-Intradural Lipoma :-Refers to a lipoma located along the dorsal
midline that is contained within the dural sac-Most commonly lumbosacral in location and
usually present with tethered-cord syndrome-No open spinal dysraphism is present (they are
contained within an intact dural sac)-See Intraspinal Masses
Intradural lipoma , Sagittal T1 (A) and sagittal T2 fat-saturated (B) in 6-year-old girl show large intradural lipoma (arrows) which is hyperintense on T1 and hypointense on T2 fat-saturated image , lipoma is attached to conus medullaris, which is low lying
Intradural lipoma , 2-month-old girl. A. Sagittal T1 shows low-lying spinal cord tethered (small arrowheads) to the anterior surface of a lumbosacral lipoma (L) , the lipoma is not continuous with the subcutaneous fat , notice concurrent dermal sinus (large arrowhead). B. Axial T1 shows the placode (P) -lipoma (L) interface (arrowheads) , the lipoma is intradural and clearly separated from the subcutaneous fat
Intradural cervical lipoma , A. Sagittal T1 show huge intradural lipoma that fills the spinal canal almost completely , the spinal cord is compressed , the spinal canal is enlarged, with scalloped posterior vertebral walls. B. Fat-suppressed sagittal T1 confirms the fatty composition of the mass
2-Filar Lipoma :-Fibrolipomatous thickening of the filum
terminale-Hyperintense strip of signal on T1 within a
thickened filum terminale-See Intraspinal Masses
Filar lipoma , 2-year-old boy. A,B. Sagittal and coronal T1 show that the filum terminale is largely replaced by fat (arrows) , the spinal cord is tethered and low. C. Axial T1 shows the hyperintense fatty filum (arrow) clearly stands out against the hypointense cerebrospinal fluid
Filar lipoma. Sagittal (A) and axial (B) T1 in 2-year-old boy with filar lipoma (arrows) , which has characteristic T1 hyperintensity and marked thickening of filum terminale
(a) T1 reveals a linear area of increased signal intensity (arrow) within the spinal canal at the inferior L2 level , the abnormality remains relatively hyperintense on (b) the T2 , On (c) the T1, the lesion (arrow) is well defined and of markedly increased signal intensity , equivalent to fat
3-Tight Filum Terminale :-Hypertrophy and shortening of the filum
terminale-This condition causes tethering of the spinal
cord and impaired ascent of the conus medullaris , the conus medullaris is low lying relative to its normal position , which is usually above the L2-L3 disk level
Sagittal T2 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
Tight filum terminale , 4-month-old girl with partial diastematomyelia , A. Sagittal T1 shows thickened filum terminale (arrow) with tethered low conus medullaris , the spinal canal is abnormally large , B. Axial T1 confirms thickening of the filum terminale (arrow)
4-Persistent Terminal Ventricle :-Persistence of a small ependymal lined
cavity within the conus medullaris-Key imaging features include location
immediately above the filum terminale and lack of contrast enhancement which differentiate this entity from other cystic lesions of the conus medullaris
Persistent terminal ventricle , Sagittal T2 (A) and sagittal T1+C (B) in 12-month-old boy show persistent terminal ventricle as cystic structure (arrows) at inferior aspect of conus medullaris which does not enhance
Persistent terminal ventricle. A. Sagittal T1 shows faint hypointensity within the conus medullaris (arrow) , there is concurrent filar lipoma (arrowheads). B. Axial T1 confirms intramedullary cavity involving the conus medullaris (arrow), at the anatomic site of the terminal ventricle
(a) The T2 sagittal shows an intramedullary slit-like focus of CSF intensity signal within the distal cord near the conus medullaris (arrow) , Grade I spondylolisthesis (short arrow) is present at L5-S1 , disc bulging (arrowhead) without cord compression is also found at T12-L1 , (b) The T2 axial at the most caudal aspect of the lesion demonstrates its location at the central canal (arrow) and confirms its intramedullary location
5-Dermal Sinus :-Epithelial lined fistula that connects neural tissue
or meninges to the skin surface-It occurs most frequently in the lumbosacral
region and is often associated with a spinal dermoid at the level of the cauda equina or conus medullaris
-Clinically, patients present with a midline dimple and may also have an associated hairy nevus , hyperpigmented patch or capillary hemangioma
Dermal sinus. Sagittal schematic (A) and sagittal T2 (B) in 9-year-old girl show intradural dermoid (stars) with tract 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)
Dermal sinus with dermoid, 8-year-old girl. A. Slightly parasagittal T2 shows sacral dermal sinus coursing obliquely downward in subcutaneous fat (arrow). B. Midsagittal T2 shows huge dermoid in the thecal sac (arrowheads) extending upward to the tip of the conus medullaris , the mass gives slightly lower signal than cerebrospinal fluid and is outlined by a thin low-signal rim
Thoracic dermal sinus , 2-month-old boy , Sagittal T1 shows dermal sinus coursing obliquely through the subcutaneous fat (arrow)
Sagittal T2 shows elongated tethered cord , terminal lipoma and dorsal dermal sinus tract
b) Complex Dysraphic States :-Can be divided into 2 categories :1-Disorders of Midline Notochordal
Integration :-Include : dorsal enteric fistula , neurenteric
cyst & diastematomyelia2-Disorders of Notochordal Formation :-Include caudal agenesis & segmental spinal
dysgenesis
1-Disorders of Midline Notochordal Integration :
a) Dorsal Enteric Fistulab) Neurenteric Cystc) Diastematomyelia
a) Dorsal Enteric Fistula :-Occur when there is an abnormal
connection between the skin surface & bowel
b) Neuroenteric Cyst :1-Incidence2-Location3-Radiographic Features4-Differential Diagnosis
1-Incidence :-Rare-Associated with vertebral anomalies (50%)-Also named endodermal cyst
2-Location :-Lined by mucin secreting epithelium similar
to the GIT and are typically located in the cervico-thoracic spine anterior to the spinal cord
-Intradural extramedullary location
3-Radiographic Features : MRI-The cyst is usually single smooth unilocular-The appearance depends on the variable protein
content but mostly :*T1 : iso to hypointense*T2 : iso to hyperintense -Marked compression of the cord-No contrast enhancement-No diffusion restriction
MRI of an intradural/extramedullary neurenteric cyst located at the craniocervical junction , Coronal (a) and sagittal (b) T1 showing the ventrally located homogenous lesion compressing the cervical spinal cord , Axial imaging demonstrates cord flattening by the anteriorly located neurenteric cyst hyperintense on both T1 (c) and T2 (d)
T1 (a,c) & T2 (b,d) show an intradural extramedullary cystic mass at the T1-T2 level
MRI of thoracolumbar junction with intradural/ extramedullary neurenteric cyst at T11 , (a) Midsagittal MRI demonstrates isointense lesion (arrow) on T1 & (b) hyperintense signal (arrow) on T2
Neurenteric cyst in 3-year-old girl. Sagittal T2 (A) and axial (B) show bilobed neurenteric cyst (arrows) extending from central canal into posterior mediastinum
Neurenteric cyst in 3-year-old girl. 3D CT reconstruction image shows osseous opening (arrow) through which neurenteric cyst passes , This opening is called the Kovalevsky canal
Neurenteric cyst , Sagittal PD shows an intradural cyst ventral to the spinal cord at the C7-T2 level
4-Differential Diagnosis :*From Tumors :-No contrast enhancement in the
Neuroenteric cyst*From Arachnoid Cyst :-Arachnoid cyst has CSF signal intensity in
all pulse sequences and not associated with vertebral anomalies
c) Diastematomyelia :-Separation of the spinal cord into two hemicords-More in females-Two types :Type 1 : with a septum (osseous or cartilaginous) ,
two separate dural sacs surround each hemicord Type 2 : no septum , single dural sac and
arachnoid space -Diastematomyelia can present clinically with
scoliosis and tethered-cord syndrome-Presence of multiple non-segmented vertebrae in
the thoracic region is a clue to the possible presence of diastomatomyelia
Type 1 Type 2
(a) Coronal CT of the thoracic spine shows fusion of the T6-T9 vertebral bodies , (b) Axial CT image of the spine at T8 shows a bony bar (arrow) creating two distinct spinal canals
Type 1 diastematomyelia , Sagittal T2 (A), axial T2 (B), and axial CT with bone algorithm (C) images in 6-year-old boy show two dural tubes separated by osseous bridge (arrows) which is characteristic for type 1 diastematomyelia
Diastematomyelia type 1 , A. Axial CT scan shows bony spur (S) separating the spinal canal into two halves each containing a separate dural sac (asterisks) , the spur articulates with the vertebral body anteriorly (arrowheads) , whereas posteriorly there is a bony spina bifida. B. Axial T1 shows the spur (S) and the dual dural tubes , each containing a hemicord (hc)
Type 2 diastematomyelia , Sagittal T1 (A), coronal T1 (B), and axial T2 (C) in 9-year-old girl show splitting of distal cord into two hemicords (white arrows, B and C) within single dural tube which is characteristic for type 2 diastematomyelia , incidental filum lipoma (black arrows, A and B) is present as well
Diastematomyelia type 2 without septum , 13-year-old girl. A. Sagittal T2 shows a low spinal cord with apparent focal thinning (arrow) resulting from partial averaging with the intervening subarachnoid space between the two hemicords. Hydromyelia (H) involves the cord above the splitting. There is associated tight filum terminale (arrowhead). B. Coronal T2 shows split hemicords (hc) and cranial hydromyelia (H). C. Axial T2 clearly shows the two hemicords (hc) contained into a single dural tube with no intervening septum
2-Disorders of Notochordal Formation :a) Caudal Agenesisb) Segmental Spinal Dysgenesis
a) Caudal Agenesis (Regression) :-In caudal regression (sacral agenesis) , there is
absence of sacrococcygeal vertebrae which in more severe cases extends to include a portion of the lumbar spine , the agenesis is limited to the sacrum in about half of cases
-May be associated with the following : anal imperforation , genital anomalies , renal dysplasia or aplasia , pulmonary hypoplasia or limb abnormalities
-Caudal agenesis can be categorized into two types :
*In type 1 : there is a high position and abrupt termination of the conus medullaris (shows characteristic wedge or hatchet-shaped appearance of the conus medullaris)
*In type 2 : there is a low position and tethering of the conus medullaris
Type 1 , abrupt termination of the cord at D12- L1 , bulbous wedge-shaped conus
Type 1 , T2 of lumbo sacral spine shows : hypoplastic S1 and S2 with failure of formation of S3 and onwards , cord ending at a higher level at D12-L1 with 'wedge' shaped termination , no cord tethering
Type 1 , (A) Lateral radiograph of lumbosacral spine reveals absence of distal sacrum (arrow) , (B) Sagittal T1 reveals abrupt termination of the conus medullaris with double bundle arrangement of nerve roots (arrow) , (C) Sagittal T1 reveals abrupt termination of the conus medullaris (arrow) and partial sacral agenesis
Type 1 , Sagittal T2 (A) and sagittal T1 (B) in 6-month-old girl show agenesis of sacrum , conus medullaris is high in position and wedge shaped (arrow) due to abrupt termination , distal cord syrinx (arrowhead) is present as well
Type 1 , 8-year-old boy , A. Sagittal T1 and B. sagittal T2 show subtotal sacrococcygeal agenesis with a rudiment of S1 as the last visible vertebra , articulating with medialized ileum (I) , the cord terminus is blunt and lies opposite the lower half of L1 (arrow) , a somewhat atypically “low” position for type I CA , there is terminal hydromyelia and “double bundle” arrangement of the nerve roots of the cauda equina , the dural sac tapers abruptly and ends abnormally high (arrowheads)
Type 2 , 3-month-old boy , Sagittal T1 shows the spinal cord is low and tethered (arrow) to an intradural lipoma (L) , the vertebral anomaly is less severe than in type I , with S3 present in this case
Type 2 , T2 shows hypoplastic sacrum , spinal cord terminating at L3 level , thickened filum terminale and tethered cord (arrow)
b) Segmental Spinal Dysgenesis :-The clinical-radiologic 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
-3D CT reconstructions can be helpful in showing various vertebral segmentation anomalies
Lateral radiograph shows marked offset between the two spinal segments above and below the dysgenesis resulting in marked kyphosis , only nine thoracic vertebrae and the corresponding pair of ribs are visible ; there is complete disconnection of the spine at the level of the dysgenesis and the lower segment shows a hypoplastic L3 (open arrow) and deformed L4 (solid arrow). , partial sacrococcygeal agenesis is also present, with only S1 through S4 visible
Vertebral segmentation anomalies , 3D CT reconstruction image (A) in 4-year-old girl and schematic illustration (B) show multiple segmentation anomalies in lumbar spine (superior to inferior beginning at level of arrow) : partial sagittal partition , butterfly vertebra , hemivertebra , tripedicular vertebra and widely separated butterfly vertebra
Segmental spinal dysgenesis , 2-month-old girl , Sagittal T2 shows acute thoracolumbar kyphosis with complete interruption of the spinal column , there are two completely separated spinal cord segments ; the upper ends several vertebral levels above the gibbus (white arrowhead) and shows hydromyelia , whereas the lower is bulky and low (arrows) , notice extreme narrowing of spinal canal at the gibbus apex (black arrowheads)
Segmental spinal dysgenesis , 8-year-old boy , Sagittal T1 shows indeterminate vertebrae at the upper lumbar level resulting in congenital kyphosis without complete disconnection of the spine , the spinal cord at the dysgenesis level is thin (arrowheads) , the conus medullaris is bulky and low (arrows)
2-Congenital Spinal Stenosis :a) Etiology b) Radiographic Features
a) Etiology :1-Short pedicles , thick laminae & large
facets2-Morquio's syndrome3-Achondroplasia (known for symptomatic
lumbar stenosis)4-Down syndrome (known for congenital
stenosis of both cervical & lumbar spines)
b) Radiographic Features :1-Cervical Spine :-Normal AP diameter is approximately 17
mm-Relative stenosis 10-13 mm-Absolute stenosis <10 mm-The width of the canal is not however
constant and progressively decreases as one moves down the cervical spine
-Torg Ratio :This is a the ratio of the diameter of cervical
canal to the width of cervical body , less than 0.8 on lateral view is consistent with cervical stenosis
2-Lumbar Spine :-12 mm is considered to be stenotic-Normally, the canal/body ratio should not
exceed 3:1
Torg Ratio
The canal / body ratio
Normal canal diameter Spinal canal stenosis
3-Scoliosis :a) Definition b) Etiologyc) Radiographic Features
a) Definition :-Lateral curvature of the spine (with a Cobb
angle greater than 10 degrees)
b) Etiology :1-Idiopathic (90 %) , typical is a S-shape curve
with the thoracic curvature convex to the right2-Congenital :-Vertebral anomalies e.g. hemivertebra can be
seen-May be associated with a congenital abnormality
such as diastematomyelia or a Chiari I malformations (with hydromyelia)
3-Neuromuscular :-Cerebral palsy 4-Post-traumatic :-Prior fracture , chronic OM , prior surgery &
radiation therapy
c) Radiographic Features :-Cobb Angle :*To measure the Cobb angle , one must first decide which
vertebrae are the end-vertebrae of the curve deformity (vertebrae at the upper and lower limits of the curve) and then Cobb angle formed by the intersection of two lines :
One parallel to the endplate of the superior end vertebra andThe other parallel to the endplate of the inferior end vertebraOr Perpendiculars are extended from the two lines of Cobb
angle resulting angle is measured from the intersection of the two perpendiculars
-Alternative Cobb Angle :*A line is extended through the mid-points of
the superior and inferior endplates of the vertebrae at the upper and lower limits of the curve , angle was derived at the point of intersection of the lines
4-Tethered Cord Syndrome :a) Etiologyb) Pathology c) Incidence d) Radiographic Features
a) Etiology :-Low position of the conus , with the conus being tethered
(held in that position) -Spinal cord tethering should be thought of as primary and
secondary :1-Primary tethered cord syndrome occurs as an
isolated anomaly2-Secondary tethered cord syndrome occurs in the setting
of other abnormalities (myelomeningocele , filum terminale lipoma , trauma & following surgical repair of meningomyelocele repair)
b) Pathology : -The spinal column develops at a greater rate than
the spinal cord during fetal development and abnormal attachments lead to abnormal stretching of the spinal cord
-Tethering may also develop after spinal cord injury and scar tissue can block the flow of fluids around the spinal cord
-Fluid pressure may cause cysts to form a syringomyelia
c) Incidence :-The condition is closely linked to spina bifida and
as such presentation in childhood may be with the cutaneous stigmata of dysraphism (hairy patch , dimple & subcutaneous lipoma)
-There may be associated foot and spinal deformities , leg weakness , low back pain , scoliosis and incontinence
-The condition may go undiagnosed until adulthood with development of sensory and motor problems and loss of bowel and bladder control
d) Radiographic Features : MRI-Low conus medullaris (below L2) and
thickened filum terminale (> 2 mm) -MRI is useful in visualizing the conus
medullaris , assessing the thickness of the filum terminale , identifying traction lesions and evaluating associated bony dysraphisms
Tethered cord with myelomeningocele
T2 shows tethered cord with lipoma , white arrows point to elongated spinal cord , black arrows indicate the lipoma
T1 in a patient who had undergone a myelomeningocele repair at birth shows that the cord ends at the L5 level (straight arrow) , note the absence of the posterior elements of the sacrum, as well as the presence of a high signal intensity mass (lipoma) within the sacral spinal canal (curved arrows)
Sagittal T2 shows elongated tethered cord , terminal lipoma and dorsal dermal sinus tract
5-Syringohydromyelia (Syrinx) :a) Definitionb) Etiologyc) Radiographic Findings
a) Definition :-Hydromyelia is defined as dilatation of the central canal of
the spinal canal , lined by ependyma-Syringomyelia is defined as the presence of a fluid-filled
cavity within the spinal cord lined by gliotic parenchyma-It is very difficult to distinguish hydromyelia from
syringomyelia and hence , the collective terms syringohydromyelia or simply "syrinx" are sometimes used to refer to a fluid collection within the cord
-Syringobulbia refers to the extension of a fluid collection into the brain stem , often accompanied by cranial nerve findings due to compression
b) Etiology :1-Congenital :-Myelomeningocele-Chiari I malformation-Chiari II malformation-Dandy-Walker malformation-Klippel-Feil syndrome2-Acquired :-Post-traumatic-Post-inflammatory-Secondary to a spinal cord tumor-Secondary to a hemorrhage-Due to vascular insufficiency
c) Radiographic Findings : MRI-CSF like intensity (Hypointense in T1 &
Hyperintense in T2)-Administration of intravenous Gadolinium
during the MRI examination is useful for detecting any associated tumor
Syringobulbia with thoracic spine hemangioblastoma
6-Spinal Cord Herniation :a) Incidenceb) Locationc) Radiographic Featuresd) Differential Diagnosis
a) Incidence :-Idiopathic thoracic spinal cord herniation is an
uncommon cause of thoracic myelopathy in which the spinal cord herniates or prolapses through an anterior or lateral defect in the dura mater
-Idiopathic herniation , which results from a dural defect of unknown origin , is distinguished from herniation with a documented traumatic cause or with postoperative origin
-Although of unknown etiology , a congenital origin has been postulated
Drawings show sagittal (a) and axial (b) views of ventral herniation of the thoracic spinal cord through a dural defect (arrows) , the spinal cord at the level of herniation appears narrowed or deformed and there is a focal accumulation of cerebrospinal fluid (CSF) in the dorsal subarachnoid space (arrowheads) , a feature that may mimic a dorsal arachnoid cyst
b) Location :-Most often occurs in the thoracic spine
between the T4 and T7 vertebrae
c) Radiographic Features : MRI-On sagittal MR images , an acute anterior kink of
the thoracic spinal cord is observed with an enlargement of the dorsal subarachnoid space
-Cord deviation is generally limited to one or two thoracic spine segments
-An extradural masslike area of signal intensity similar to that of the spinal cord may be observed occasionally and it represents the herniated spinal cord
-Associated cord atrophy and high T2 signal intensity may be observed within the thoracic cord
(a) T2 shows a focal anterior kink of the spinal cord at the T6-7 level (arrows) , (b) Sagittal reformatted image from CT myelography shows widening of the dorsal subarachnoid space without any apparent filling defect (arrowheads) , adjacent areas of high attenuation (arrows) likely represent calcified material from chronic disk herniation
Axial CT myelogram clearly demonstrates herniation of the left anterolateral portion of the cord (arrows) through a dural defect (arrowheads)
(a–c) Sagittal T2 (a) and T1 (b) MR images and sagittal reformatted image from CT myelography (c) show typical characteristics of idiopathic herniation , including focal thinning of the spinal cord (arrows in a and b) and widening of the dorsal subarachnoid space (arrowheads in c) because of anterior displacement of the cord at the T6-7 vertebral level
d) Differential Diagnosis :-it is important to exclude a dorsally located
cystic lesion (e.g. an intradural arachnoid cyst) which may mimic a cord herniation
Arachnoid Cyst , Sagittal T2 shows a well-defined lesion (arrows) within the dura mater , dorsal to the spinal cord which is displaced anteriorly , the signal within the lesion is slightly hyperintense compared with the CSF signal and thin margins visible at the superior and inferior ends of the lesion are suggestive of a cyst
7-Neurofibromatosis :a) Spinal Manifestations in NF1b) Spinal Manifestations in NF2
a) Spinal Manifestations in NF1 :1-Posterior scalloping of the vertebral bodies2-Lateral meningocele3-Neurofibromas of exiting nerve roots (with
enlargement of the neural foramina)4-Plexiform neurofibromas of the paraspinal
& sacral regions are also common5-Multiple cutaneous neurofibromas are the
hallmark of this disease
Posterior scalloping of the vertebral bodies
Posterior scalloping of the vertebral bodies
Sagittal T2 showing posterior vertebral scalloping by dural ectasia (asterisks)
Lateral meningocele
Lateral meningocele
Neurofibromas
Plexiform Neurofibroma
Plexiform Neurofibroma , MRI Lumbar spine show a neoplastic soft tissue completely occupying lumbosacral spinal canal , enhancement on T1+C , punctate low signal intensities on T2 & T1+C , expansion of spinal canal with marked posterior vertebral scalloping , extending out of neural foramen on either side
Plexiform Neurofibroma , Coronal FSE fat-suppressed T2 : multiple ovoid-shaped high signal intensity neurofibromas are seen throughout the sacral and pelvic regions , note that some neurofibromas demonstrate characteristic target sign
Plexiform Neurofibroma , (a) Axial FSE fat-suppressed T2 shows extensive, conglomerate masses in the pelvis , gluteal region and along the bilateral sciatic nerves , (b) Coronal FSE fat-suppressed T2 of the same patient demonstrates that neurofibromas have a characteristic bright signal intensity
b) Spinal Manifestations in NF2 :1-Intradural tumors are very common in NF2 :-Extramedullary lesions include schwannomas and
meningiomas with neurofibromas are less common
-Intramedullary lesions include astrocytomas and ependymomas , although these are less common in comparison with extramedullary lesions
2-Bilateral vestibular schwannomas are pathognomonic for this disease
8-Klippel-Feil Syndrome :a) Definitionb) Associations
a) Definition :-Failure of segmentation of two or more
cervical vertebrae (most commonly C2-3 or C5-6) that results in cervical vertebral fusion
b) Associations :1-Deafness2-Congenital heart disease (anomalies of
the aortic arch and branching vessels)3-Sprengel deformity4-Urologic abnormalities (e.g. unilateral
renal agenesis)
9-Achondroplasia :a) Incidenceb) Radiographic Features
a) Incidence :-Autosomal dominant disorder-The most common cause of dwarfism
b) Radiographic Features :-Narrowed interpedicular distance (the distance
measured between the pedicles on frontal / coronal imaging) with short pedicles leading to spinal stenosis
-In the cervical spine there can be generalized spinal canal stenosis with stenosis at the foramen magnum also known to be associated (potentially resulting in cervicomedullary compression
-Small spinal canal leads to posterior vertebral scalloping
Posterior vertebral scalloping
Stenosis of the foramen magnum
