Presentation1.pptx, radiological imaging of congenital anomalies of the spine and spinal cord.
Radiological imaging of congenital
anomalies of the spine and spinal cord.
Dr/ ABD ALLAH NAZEER. MD.
Congenital abnormalities of the spine and spinal cord
are referred to as spinal dysraphisms. Reviews
normal embryological development of the spine
and spinal cord and the imaging findings of
congenital abnormalities of the spine and spinal
cord with particular focus on MRI.
Etiology: Multifactorial, Genetic, environmental
factor and folic acid deficiency.
The most common congenital anomalies is spinal
dysraphism and the caudal spinal anomalies.
The diagnosis is either prenatally by ultrasound, at
birth, in the early childhood and in adulthood.
Spinal Cord Development
Spinal development can be summarized in three basic embryologic
stages. The first stage is gastrulation and occurs during the second
or third week of embryonic development. Gastrulation involves
conversion of the embryonic disk from a bilaminar disk to a
trilaminar disk composed of ectoderm, mesoderm, and endoderm.
The second stage in spinal development is primary neurulation
(weeks 3–4) in which 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 bidirectionally in a zipper like
manner (Fig. 1). The final stage of spinal development is secondary
neurulation (weeks 5–6). During this stage, a secondary neural tube
is formed by the caudal cell mass. The secondary neural tube is
initially solid and subsequently undergoes cavitation, eventually
forming the tip of the conus medullaris and filum terminale by a
process called retrogressive differentiation. Abnormalities in any of
these steps can lead to spine or spinal cord malformations.
Neurulation and derangement of neurulation:
Four stages of neurulation:
1- Formation of neural tube.
2- Shaping the neural plate.
3- Bending of the neural plate.
Formation of neural tube.
Shaping the neural plate.
Bending of the neural plate.
Categorization of Spinal Dysraphisms:
Spinal dysraphisms can be broadly categorized into open
and closed types. In an open spinal dysraphism, there
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.
Classification of spinal dysraphisms.
Open Spinal Dysraphisms: not covered by intact skin:
Myelocele Neural placode flush with skin surface
Myelomeningocele Neural placode protrudes above skin surface
Hemimyelocele Myelocele associated with diastematomyelia
Hemimyelomeningocele Myelomeningocele associated with diastematomyelia
Closed Spinal Dysraphisms: covered by intact skin
With a subcutaneous mass:
Lipomyelocele Placode–lipoma interface within the spinal canal.
Lipomyelomeningocele Placode–lipoma interface outside of the spinal canal.
Meningocele Herniation of CSF-filled sac lined by dura.
Terminal myelocystocele Terminal syrinx herniating into posterior meningocele.
Myelocystocele Dilated central canal herniating through posterior spina bifida
Without a subcutaneous mass Simple dysraphic states
Intradural lipoma. Lipoma within the dural sac.
Filar lipoma. Fibrolipomatous thickening of filum.
Tight filum terminale. Hypertrophy and shortening of filum.
Persistent terminal ventricle. Persistent cavity within conus medullaris.
Dermal sinus. Epithelial lined fistula between neural
tissue and skin surface.
Complex dysraphic states
Dorsal enteric fistula. Connection between bowel and skin surface
Neurenteric cyst. More localized form of dorsal enteric fistula.
Diastematomyelia . Separation of cord into two hemicords.
Caudal agenesis. Total or partial agenesis of spinal column.
Segmental spinal dysgenesis. Various segmentation anomalies.
Open Spinal Dysraphisms:
Myelomeningocele and myelocele—Myelomeningoceles and
myeloceles are caused by 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. Myelomeningoceles account
for more than 98% of open spinal dysraphisms. Myeloceles are rare.
Open spinal dysraphisms are often diagnosed clinically, so imaging is
not always performed. When imaging is performed, the main
differentiating feature between a myelomeningocele and myelocele is
the position of the neural placode relative to the skin surface. The
neural placode protrudes above the skin surface with a
myelomeningocele and is flush with the skin surface with a myelocele.
Hemimyelomeningocele and hemimyelocele—
Hemimyelomeningoceles and hemimyeloceles can also occur but are
extremely rare. These conditions occur when a myelomeningocele or
myelocele is associated with diastematomyelia (cord splitting) and one
hemicord fails to neurulate.
Spina Bifida aperta: Myelocele and myelomeningocele.
Spina bifida aperta designates those forms of spinal dysraphism in which
the neural tissue and meninges are exposed to environment because the
skin, fascia, muscles and the bone are deficient in the midline of the back.
Myelocele and Myelomeningocele
Both myelocele and myelomeningocele are the result of nondisjunction of
the cutaneous ectoderm from the neural ectoderm and failure of neural
tube closure. The nonneurulated cord or placode is exposed through a dural,
bony, and cutaneous defect (i.e., myelocele; The dorsal and ventral nerve
roots exit from the ventral surface of the placode. With associated dorsal
protrusion of the ventral subarachnoid space, the myelodysplasia is termed
a myelomeningocele. These defects commonly occur at the lumbar or sacral
level. Occasionally there is an associated diastematomyelia
(hemimyelomeningocele) or dermal sinus. These defects are surgically
closed shortly after birth. Hydrocephalus is often present; if so, shunting is
established early. Subsequently, patients who have undergone such
procedures may sac stenosis, progressive scoliosis, and cord ischemia or
A B C
A, Axial schematic of myelomeningocele shows neural placode (star) protruding above skin
surface due to expansion of underlying subarachnoid space (arrow).
B, Axial T2-weighted MR image 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.
C, Sagittal T2-weighted MR image from same patient as in B with myelomeningocele
shows neural placode (white arrow) protruding above skin surface due to expansion
of underlying subarachnoid space (black arrow).
A, Axial schematic of myelocele shows neural placode (arrow) flush with skin surface.
B, Axial T2-weighted MR image 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.
Chiari malformation, also known as Arnold–Chiari malformation,
is a malformation of the brain. It consists of a downward
displacement of the cerebellar tonsils through the foramen
magnum (the opening at the base of the skull), sometimes causing
non-communicating hydrocephalus as a result of obstruction of
cerebrospinal fluid (CSF) outflow. The cerebrospinal fluid outflow is
caused by phase difference in outflow and influx of blood in the
vasculature of the brain. It can cause headaches, fatigue, muscle
weakness in the head and face, difficulty swallowing, dizziness,
nausea, impaired coordination, and, in severe cases, paralysis.
In the late 19th century, Austrian pathologist Hans Chiari described
seemingly related anomalies of the hindbrain; the so-called Chiari
malformations I, II and III. Later, other investigators added a fourth
(Chiari IV) malformation. The scale of severity is rated I - IV, with IV
being the most severe. Types III and IV are very rare.
A congenital malformation. Is generally asymptomatic during
childhood, but often manifests with headaches and cerebellar
symptoms. Herniation of cerebellar tonsils. Tonsillar ectopia of
more than 3 mm below foramen magnum. Syringomyelia of
cervical or cervicothoracic spinal cord can be seen. Sometimes
the medullary kink and brainstem elongation can be seen.
Syndrome of occipito atlantoaxial hypermobility is an acquired
Chiari I malformation in patients with hereditary disorders of
connective tissue. Patients who exhibit extreme joint
hypermobility and connective tissue weakness as a result of
Ehlers-Danlos syndrome or Marfan syndrome are susceptible
to instabilities of the craniocervical junction; thus they are at
risk for acquiring a Chiari malformation. This type is difficult to
diagnose and treat.
Usually accompanied by a lumbar or lumbosacral
myelomeningocele with tonsillar herniation below the
foramen magnum. As opposed to the less pronounced
tonsillar herniation seen with Chiari I, there is a larger
cerebellar vermian displacement. Low lying torcular
herophili, tectal beaking, and hydrocephalus with
consequent clival hypoplasia are classic anatomic
associations. The position of the torcular herophili is
important for distinction from Dandy-Walker syndrome in
which it is classically upturned. This is important because the
hypoplastic cerebellum of Dandy-Walker may be difficult to
distinguish from a Chiari malformation that has herniated or
is ectopic on imaging. Colpocephaly may be seen due to the
associated neural tube defect.
Fetal T2-weighted MR images. A, Chiari II malformation ( arrows ) on sagittal
image. B, Lumbosacral myelocele with low-placed spinal cord ( arrow ) on
axial image. C, Dysraphic defect plus placode ( arrow) on axial image.
Chiari II malformation ( arrows in A ) and lumbosacral myelomeningocele
( arrow in B ) on sagittal T2-weighted fetal MR images.
Type II Chiari malformation in a 14-month-old child. Sagittal T1-weighted
images demonstrating hydrocephalus (A) with a small posterior fossa
and downward herniation of the cerebellum and medulla (B).
It is associated with an occipital encephalocele
containing a variety of abnormal neuroectodermal
tissues. Syringomyelia and tethered cord as well as
hydrocephalus is also seen.
Characterized by a lack of cerebellar development
in which the cerebellum and brain stem lie within
the posterior fossa with no relation to the foramen
magnum. Associated with hypoplasia. Equivalent
to primary cerebellar agenesis.
Closed Spinal Dysraphisms With a Subcutaneous Mass
Lipomas with a dural defect—Lipomas with a dural defect
include both lipomyeloceles and Lipomyelomeningocele.
These abnormalities result from a defect in primary
neurulation whereby mesenchymal tissue enters the neural
tube and forms lipomatous tissue. Lipomyeloceles and
lipomyelomeningoceles are characterized clinically by the
presence of a subcutaneous fatty mass above the
intergluteal crease. The main differentiating feature
between a lipomyelocele and lipomyelomeningocele is the
position of the placode–lipoma interface . With a
lipomyelocele, the placode–lipoma interface lies within the
spinal canal. With a lipomyelomeningocele, the placode–
lipoma interface lies outside of the spinal canal due to
expansion of the subarachnoid space.
Meningocele—Herniation of a CSF-filled sac
lined by dura and arachnoid mater is referred to
as a meningocele. The spinal cord is not located
within a meningocele but may be tethered to
the neck of the CSF-filled sac. Posterior
meningoceles herniate through a posterior
spina bifida (osseous defect of posterior spinal
elements) and are usually lumbar or sacral in
location but also can occur in the occipital and
cervical regions. Anterior meningoceles are
usually presacral in location but also can occur
A, Axial schematic of lipomyelocele shows placode–lipoma interface (arrow) lies within
spinal canal. B, Axial T2-weighted MR image in 3-year-old girl shows placode–lipoma
interface (arrow) within spinal canal, characteristic for lipomyelocele. C, Sagittal T1-
weighted MR image in 3-year-old girl with lipomyelocele shows subcutaneous fatty mass
(black arrow) and placode–lipoma interface (white arrow) within spinal canal.
Lipomyelocele with placode ( short arrows ), lipoma (L), and caudal hydromyelia
( long arrows ) on sagittal ( A ) and axial T1-weighted ( B ) MR images.
Lumbosacral lipomyelocele with caudal and presacral lipomas (L) and hydrosyringomyelia
( arrows ) on sagittal T1-weighted ( A ) and T2-weighted ( B ) MR images
A, Sagittal T1-weighted MR image in in 12-month-old girl shows posterior herniation of
CSF-filled sac (arrow) in occipital region, consistent with posterior meningocele.
B, Sagittal T2-weighted MR image in 5-year-old boy shows large posterior meningocele
(arrow) in cervical region. C, Sagittal T2-weighted MR image in 30-month-old girl shows
small posterior meningocele (arrow) in lumbar region.
A and B, Sagittal (A) and axial (B)
T2-weighted MR images in 6-
month-old boy show small
anterior meningocele (arrows).
Sagittal ( A ) and axial ( B and C ) T2-weighted MR images showing dural ectasia
and intradural arachnoid cysts ( arrows in A ) with scoliosis, cord flattening ( short
arrows in B and C ), and transforaminal meningoceles ( long arrows in B and C ).
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.
Myelocystocele—A 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 regions.
A, Sagittal schematic of terminal myelocystocele shows terminal syrinx (star)
herniating into large posterior meningocele (arrows). B and C, Sagittal (B) and
axial (C) T2-weighted MR images 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, B).
Closed Spinal Dysraphisms Without a Subcutaneous Mass
Closed spinal dysraphisms without a subcutaneous mass can be
subcategorized into simple and complex dysraphic states. Simple
dysraphic states—Simple dysraphic states consist of intradural lipoma,
filar lipoma, tight filum terminale, persistent terminal ventricle, and
dermal sinus. An intradural lipoma refers to a lipoma located along the
dorsal midline that is contained within the dural sac. No open spinal
dysraphism is present. Intradural lipomas are most commonly
lumbosacral in location and usually present with tethered-cord
syndrome, a clinical syndrome of progressive neurologic abnormalities
in the setting of traction on a low-lying conus medullaris.
Fibrolipomatous thickening of the filum terminale is referred to as a
filar lipoma. On imaging, a filar lipoma appears as a hyperintense strip
of signal on T1-weighted MR images within a thickened filum
terminale. Filar lipomas can be considered a normal variant if there is
no clinical evidence of tethered-cord syndrome . Tight filum terminale is
characterized by hypertrophy and shortening of the filum terminale.
The Tethered Cord Syndrome:
Also known as “tight filum terminale syndrome,” tethered
cord syndrome refers to low position of the conus
medullaris (below the level of mid-L2) associated with a
short and thickened filum terminale. The filar thickening
(usually greater than 2 mm) is usually fibrous, fatty, or
cystic, and may be associated with other dysraphic
myelodysplasias, including lipomyelomeningocele and
diastematomyelia. The thickened filum may also
terminate in a lipoma or dermoid-epidermoid. The filar
abnormality is usually best demonstrated on axial T 1 -
weighted and T 2 -weighted MRI.
A and B, Sagittal (A) and axial (B) T1-
weighted MR images in 2-year-old boy
with filar lipoma (arrows), which has
characteristic T1 hyperintensity and
marked thickening of filum terminale.
Sagittal ( A ) and axial ( B and C ) T1-weighted MR images showing
tethered cord with low conus ( short arrows in A and B ), dorsal lipoma
( long arrows in A and B ), and filar lipoma ( arrow heads in A and C ).
Sagittal ( A ) and axial ( B and C ) T1-weighted MR images showing
lumbosacral dermal sinuses ( black arrows on A and C ) with tethered cord
( white arrows in A ) and lipoma ( white arrows in B and C ) in a newborn.
Tethered cord ( long arrow ), thick filum and lipoma ( short arrows ),
and sacral extradural arachnoid cyst (A) on sagittal T1-weighted ( A ),
axial T1-weighted ( B ), and axial T2-weighted ( C ) MR images.
Complex dysraphic states—Complex dysraphic states
can be divided into two categories: disorders of midline
notochordal integration, which include dorsal enteric
fistula, neurenteric cyst, and diastematomyelia, and
disorders of notochordal formation, which include caudal
agenesis and segmental spinal dysgenesis. Disorders of
midline notochordal integration: Dorsal enteric fistula and
neurenteric cyst—A dorsal enteric fistula occurs when
there is an abnormal connection between the skin surface
and bowel. Neurenteric 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.
Neurenteric cyst in 3-year-old girl.
A and B, Sagittal T2-weighted (A) and axial T1-weighted (B) MR images show bilobed
neurenteric cyst (arrows) extending from central canal into posterior mediastinum.
C, Three-dimensional CT reconstruction image shows osseous opening (arrow) through
which neurenteric cyst passes. This opening is called the Kovalevsky canal.
Terminal ventricle: Persistence of a small, ependymal
lined cavity within the conus medullaris is referred to as a
persistent terminal ventricle. 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.
A dermal sinus is an 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. Surgical repair is of great importance because the
fistulous connection between neural tissue and the skin surface can
result in infectious complications such as meningitis and abscess.
Persistent terminal ventricle.
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 enhance.
A and B, Sagittal schematic (A) and sagittal T2-weighted MR image (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).
Thoracic dermal sinus ( black arrows ) and dermoid cyst (
white arrows ) on sagittal T1-weighted ( A ), sagittal T2-
weighted ( B ), and axial T1-weighted ( C ) MR images.
Thoracic dermal sinus ( posterior black and white arrows in A, and B ) and cyst
with enhancing abscess ( anterior white arrows in B ) with cord edema on sagittal
T2-weighted ( A ) and gadolinium-enhanced T1- weighted ( B ) MR images.
Disorders of midline notochordal integration:
Diastematomyelia—Separation of the spinal cord into
two hemicords is referred to as diastematomyelia.
The two hemicords are usually symmetric, although
the length of separation is variable. There are two
types of diastematomyelia. In type 1, the two
hemicords are located within individual dural tubes
separated by an osseous or cartilaginous septum. In
type 2, there is a single dural tube containing two
hemicords, sometimes with an intervening fibrous
septum. Diastematomyelia can present clinically with
scoliosis and tethered-cord syndrome. A hairy tuft on
the patient’s back can be a distinctive finding on
Type 1 diastematomyelia.
A–C, Sagittal T2-weighted MR (A), axial T2-weighted MR (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.
Lumbar diastematomyelia and split cord with two hemicords ( short arrows in
A and B ), two dural sacs, and a bony septum ( long arrows in B and C ) on
axial T2-weighted MR images ( A and B ) and an axial CT scan ( C ).
Type 2 diastematomyelia.
A–C, Sagittal T1-weighted (A), coronal T1-weighted (B), and axial T2-weighted (C) MR
images 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.
Lumbar diastematomyelia with tethered hemicords ( long
arrows ), no septum, and a lipoma ( short arrow ) on sagittal
T1-weighted ( A ) and axial T2-weighted ( B ) MR images.
Disorders of notochordal formation:
Caudal agenesis—Caudal agenesis refers to total or partial
agenesis of the spinal Column and 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. In
type 2, there is a low position and tethering of the conus
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. Three-dimensional CT reconstructions can be helpful
in showing various vertebral segmentation anomalies
A and B, Sagittal T2-weighted (A) and sagittal T1-weighted (B) MR images in 6-
month-old girl 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.
Caudal dysplasia with high imperforate anus, congenital lumbar kyphosis
( long arrow s), and dysplastic/hypoplastic conus medullaris ( short arrow
) on sagittal ( A ) and coronal ( B ) T1-weighted MR images.
MRI Sagittal T2w images 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. No
terminal cord cyst or syrinx. Imaging diagnosis : Caudal Regression, Group I.
Teratoma - Genetics
A teratoma is a disordered mass of cells which exhibit varying
degrees of resemblance to normal tissues and structures. Disrupted
or incomplete twinning versus uncontrolled stem cell?
Some ovarian teratomas – parthenogenetic oocysts ? Fetus in fetus.
Other teratomas - arise from stem cells
Vertebral segmentation anomalies. A and B, Three-dimensional 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.
Limbus vertebra. Lateral radiograph (a) and sagittal thin slab reformatted
MDCT images (b,c) show the defect at the anterosuperior border of L4.
Limbus vertebra. Axial MDCT image (a) and oblique
volume rendered images (b) show a limbus vertebra.
L5 transitional vertebra in a 40-year-old woman who presented with left-sciatic
pain. Axial thin-section (a) and coronal volume-rendered (b) MDCT
images show A transitional lumbosacral vertebra, with a left hypertrophic
transverse process (arrow) that articulates with the ilium and sacrum.
Spondylodysplasia refers to any developmental abnormality of
the bony spinal column. This category includes idiopathic
scoliosis, congenital scoliosis and kyphosis, Scheuermann
disease, and the skeletal dysplasias (e.g., NF-1,
mucopolysaccharidoses, spondyloepiphyseal dysplasia,
Achondroplasia, Down syndrome). Spinal curvature
abnormalities are common in this category. As defined by
clinical examination and findings on standing plain films, they
include scoliosis (lateral curvature), kyphosis (posterior
angulation), and lordosis (increased anterior angulation). In
the skeletal dysplasias, a major concern is mechanical
compromise of the spinal neuraxis due to progressive
canal/foraminal stenosis, kyphoscoliosis, or craniocervical
instability. Evaluation usually requires both CT and MRI.
Idiopathic scoliosis is the most common curvature abnormality in
childhood. The adolescent form, which is seen in children older than 10
years, is more common than the infantile or juvenile form. Adolescent
idiopathic scoliosis is familial and most commonly seen in females.
Characteristically, there is a right convex primary curve of the thoracic,
thoracolumbar, or lumbar spine A rotatory component with pedicle
asymmetry is characteristic, and a left convex secondary curve may
present. Additional lordosis often occurs with curve progression.
Complications of idiopathic scoliosis include curve progression,
cardiopulmonary compromise, painful curves, cosmetic deformity,
neurologic dysfunction, and degenerative joint disease.
Congenital scoliosis and kyphosis result from formation or
segmentation Anomalies . Failure of formation may result in
vertebral aplasia or hypoplasia with wedge vertebra, hemivertebra,
or butterfly vertebra. Anomalies of segmentation failure include
pedicle fusion bars and block vertebra.
lateral and rotatory
curvature on a
A and B, Congenital lumbar scoliosis
with hemivertebrae ( arrows in A )
and hydrosyringomyelia ( arrows in
B ) on coronal T2-weighted MR
images. The hemivertebrae ( arrows
) and double curve are confirmed on
coronal reformatted CT scan ( C )
and 3D reconstruction ( D ).
An osteochondrodysplasia, Scheuermann disease is a common cause of
juvenile and adolescent thoracic kyphosis. An abnormality of enchondral
ossification is associated with degenerative and reactive changes of the
vertebral end plates. Often there is multilevel end plate irregularity, disk
space narrowing, vertebral body wedging, and Schmorles nodes . The
kyphosis commonly occurs in the mid-thoracic spine. There may be
progressive wedging with increasing thoracic kyphosis and lumbar lordosis.
Scheuermann disease with multilevel, irregular
thoracic disk space narrowing ( long arrows )
and Schmorl’s nodes ( short arrows ).
Neurofibromatosis Type 1:
NF-1 is a common mesodermal dysplasia of childhood
Characteristic anomalies include a short-segment
kyphoscoliosis, posterior vertebral body scalloping,
vertebral body wedging, apical vertebral rotation,
dural ectasia, and meningoceles (e.g., thoracic,
presacral). There may also be an associated plexiform
neurofibroma and other nerve sheath tumors. Other
anomalies are cervical kyphosis, hypoplasia of the
spinous process, transverse process, or pedicle, and
twisted-ribbon ribs. Dural ectasia and meningocele
formation may also be seen with Marfan or Ehlers-
Danlos syndrome and in familial cases.
A, Neurofibromatosis-1 with short-segment right lumbar scoliosis plus
vertebral and rib deformities ( arrows ) on frontal plain film/computerized
radiograph. B, Enhancing paraspinal plexiform neurofibroma ( arrows ) with
foraminal extension is shown on coronal gadolinium-enhanced T1-weighted
MR image along with other small intradural enhancing nerve sheath tumors.
Achondroplasia is one of the osteochondrodysplasia (defective
enchondral bone development) resulting in dwarfism. There is
craniofacial dysmorphia with skull base constriction, including
foramen magnum stenosis, short clivus, and small jugular
Foramina. Macrocephaly and hydrocephalus (e.g., impaired
venous outflow) occur, and there is enlargement of the
subarachnoid spaces and ventricles. Other craniocervical
abnormalities include odontoid hypoplasia, atlantoaxial (AA)
instability, basilar impression, and occipitalization of the atlas.
Scoliosis, kyphosis, or kyphoscoliosis may occur in about one third
of patients with achondroplasia. Stenosis of the spinal canal may
be cervical, thoracolumbar, lumbar, or may occur diffusely. There
is platyspondyly with short pedicles, vertebral scalloping, and
interpediculate narrowing. There may be associated spinal
foraminal and canal compromise.
Achondroplasia, basilar invagination, and foramen magnum plus
cervical spinal stenosis ( arrows ) on sagittal T1-weighted MR image
( A ), sagittal reformatted CT scan ( B ), and an axial CT scan ( C ).
Also, there is characteristic macrocephaly and ventriculomegaly.
Mucopolysaccharidosis may be associated with craniocervical
abnormalities (e.g., Morquio syndrome; They include odontoid
hypoplasia, occipital hypoplasia, ligamentous laxity, AA
instability, and dural sac stenosis (mucopolysaccharide deposition
with fibrosis; Foraminal and spinal canal encroachment may
occur. Other vertebral anomalies are platyspondyly, beaking,
wedging, gibbus deformity, and kyphoscoliosis.
Down syndrome may be complicated by craniocervical instability,
such as odontoid hypoplasia, os odontoideum, atlanto-occipital
(AO) subluxation, or AA subluxation Scoliosis, degenerative
cervical spine disease, tall vertebral bodies, vertebral fusions, and
subluxations at other levels may also occur.
A, Morquio syndrome with craniocervical instability ( upper arrow ) plus
thoracolumbar kyphoscoliosis ( lower arrow ) on a lateral plain
film/computerized radiograph. B and C, Sagittal T2-weighted MR images
show upper cervical dural sac stenosis with hyperintense cord injury ( arrow in
B ) along with ventral cord deformity at the level of the kyphosis ( arrow in C ).
Lateral plain film/computerized radiograph ( A ), axial CT scan ( B ), and
sagittal reformatted CT scan ( C ) showing Down syndrome with hypoplastic
dens, os odontoideum (o), atlantoaxial instability, and post-dental canal
stenosis ( short arrows ) with probable cord compression; C2, axis; a, anterior
arch of atlas; p, posterior arch of atlas; b, basion; op, opisthion.
A, Sagittal T2-weighted MR image showing Down syndrome with hypoplastic dens, os
odontoideum ( anterior arrow ), and atlantoaxial dislocation with high-intensity cervical
spinal cord compressive injury ( posterior arrows ). B, Sagittal postoperative reformatted
CT scan shows the stabilized anomaly, including the os odontoideum ( upper arrow ),
decompressed canal, and metallic instrumentation plus bony fusion ( posterior arrows ).
Basilar invagination refers to an occipital dysplasia with upward
displacement of the margins of the foramen magnum anteriorly,
posteriorly, laterally, or combined . The odontoid is superiorly
displaced relative to McRae’s line. In addition the posterior fossa
may be of small volume with an irregularly shaped foramen
magnum and a short clivus. Basilar invagination may be (1)
primary (i.e., developmental) and associated with other
craniocervical anomalies or syndromes or (2) secondary (i.e.,
basilar impression) and associated with osteochondral dysplasias
or metabolic disorders (e.g., rickets, fibrous dysplasia,
achondroplasia, the mucopolysaccharidoses, osteogenesis
imperfecta,osteomalacia, cleidocranial dysplasia). Basilar
invagination may produce neural, CSF, or vascular compromise.
There may be an associated Chiari I malformation,
hydrocephalus, or hydrosyringomyelia.
Basilar invagination and
Chiari I malformation on
sagittal T2-weighted MR
image with short clivus and
high dens ( anterior arrows
)plus low tonsils and low
posterior arrows ).
Klippel-Feil Anomaly and Syndrome:
The Klippel-Feil anomaly , which results from failure of segmentation,
manifests as bony fusion of the cervical spine at one or more levels . The triad
of low posterior hairline, short webbed neck, and limitation of neck motion
represents the Klippel-Feil syndrome . Sprengel’s deformity of the scapula and
a bridging omovertebral bone may also be present in Klippel-Feil syndrome.
Other associated anomalies are genitourinary, cardiac, and musculoskeletal
(e.g., limbs and digits). The spinal involvement may include posterior element
abnormalities, occipitalization of the atlas, basilar impression, dens
anomalies, and scoliosis. Chiari I malformation, hydrosyringomyelia,
neurenteric cyst, or diastematomyelia may occur. Hypermobility and
instability at unfused segments and early degenerative disease may lead to
foraminal or spinal canal stenosis, osteophytic spurs, subluxation, facet
arthropathy, or disk herniation.
Occipitalization of the atlas refers to complete or partial fusion of the atlas
to the occiput, which may be bony or fibrous. Usually, the anterior arch is
assimilated into the anterior rim of the foramen magnum. The involvement may
also include the posterior arch or lateral masses. Associated anomalies are
odontoid hypoplasia, basilar invagination, AA instability, and Klippel-Feil anomaly.
Sagittal ( A ) and coronal ( B ) reformatted CT scans showing Klippel-Feil anomaly,
occipitalization of the atlas, and cervical spinal stenosis, including fused cervical
segments ( lower arrows ), fusion of atlas to the occiput ( upper black arrows ),
and a small foramen magnum and C1 canal. Flexion ( C ) and extension ( D ) T2-
weighted sagittal MR images show no translational craniocervical instability.
Anomalies of the odontoid include aplasia, hypoplasia, and the os odontoideum.
Aplasia is rare and causes severe AA dislocation. Hypoplasia leads to a short dens.
Os odontoideum is a proatlas remnant or represents hypertrophy of the ossiculum
terminale. Usually, there is odontoid hypoplasia, and the ossicle is located near
the dens tip or the basion and lacks a normal dens fusion line. Hypertrophy of the
anterior arch and hypoplasia or clefting of the posterior arch are often present.
AA or occipitoaxial instability commonly occurs. Odontoid anomalies may be
idiopathic or may be associated with skeletal dysplasias such as Morquio
syndrome, Down syndrome, SED, and Klippel-Feil anomaly.
Craniocervical instability includes translational or rotary AA instability and AO
instability. Craniocervical instability often results from ligamentous deficiency or
insufficiency (e.g. transverse ligament in AA instabilities) and is commonly
associated with odontoid anomalies (as discussed earlier). AA and AO instabilities
most commonly occur with Down syndrome. Other common causes are the
skeletal dysplasias (e.g., Morquio syndrome, SED), rheumatoid arthritis, and
trauma. Rotary AA instability includes displacement, subluxation, or dislocation
and produces torticollis. It may be spontaneous or related to trauma, infection,
or CCJ anomalies (e.g., odontoid anomalies, Klippel-Feil anomaly).
Craniocervical Instability secondary to tear of the transverse ligament.
Spondylolisthesis is a condition that involves a forward slip of a vertebra
or vertebrae in relation to the rest of the spinal column. Herbinaux first
described the condition in 1782 as a protruding sacral bone that
complicated labor. Typically, this defect occurs between the fifth lumbar
vertebra and the sacrum . However, spondylolisthesis has also been seen
between the fourth and fifth lumbar vertebral levels and may even occur
in the cervical region. The patients showed deficits in their neurological
examinations and required stabilization and fusion. Studies showing an
increase among family members with this defect suggest a genetic
component. There are various types of spondylolisthesis. Thus, a
classification system was established to differentiate the specific
etiologies. Congenital spondylolisthesis, which is a Newman Type I
defect. The cause of congenital or dysplastic spondylolisthesis, which is
most commonly found at the lumbosacral junction, occurs as a result of
an elongation of the pars interarticularis along with varying degrees of
facet joint dysplasia . Patients may present with back pain, radicular
complaints, tight hamstrings and various neurological symptoms.
Spinal Vascular Anomalies:
Vascular anomalies of childhood may involve the paraspinal soft tissues,
bony spinal column, spinal neuraxis, meninges, or multiple structures.
Vascular anomalies of the CNS have traditionally been classified as
arteriovenous malformations (AVMs), developmental venous anomalies,
cavernous malformations, telangiectasias, and aneurysms. Intradural
spinal vascular anomalies are usually AVMs or arteriovenous fistulae
(AVFs) and are classifi d according to the anatomic site of origin or
involvement. They may be classified as spinal cord AVMs (intramedullary),
spinal dural AVFs, or metameric AVMs (Cobb syndrome), the last involving
any or all layers of a spinal segment from the spinal cord to the skin. In
spinal AVMs that are “high-flow” malformations, MRI may show nodular,
serpiginous signal voids without tumor parenchyma, hemorrhage
(subarachnoid or intramedullary), cord edema, infarct, myelomalacia,
syrinx, or atrophy. Spinal AVFs may be “high-flow” or “low-flow”
malformations. Spinal angiography is necessary for full evaluation of the
vascular anomaly in anticipation of surgery or interventional therapy.
Cavernous angiomas of the spinal cord are rare and may manifest as
hemorrhage (subarachnoid or intramedullary) or myelopathy.
Cervical spinal cord arteriovenous malformation with high-flow vascular low
intensities ( arrows ) on sagittal T1-weighted ( A ) and T2-weighted ( B ) MR images.
Spina bifida (Latin : "split spine") is a developmental congenital
disorder caused by the incomplete closing of the embryonic neural
tube . Spina bifida malformations fall into three categories: spina
bifida occulta, spina bifida cystica with meningocele, and spina
bifida cystica with myelomeningocele. The most common location
of the malformations is the lumbar and sacral areas.
Myelomeningocele is the most significant and common form, and
this leads to disability in most affected individuals. The terms spina
bifida and myelomeningocele are usually used interchangeably.
Sagittal and axial MR images at the level of the
L7-S1 disk of a young Bulldog with spina bifida.
Congenital malformations of the spine and spinal cord
can be complex and variable in imaging appearance.
An organized approach to imaging findings with
consideration of clinical and developmental factors
allows greater ease in diagnosis.
Spinal dysraphism or neural tube defect is a broad
term encompassing a heterogenous group of
congenital spinal anomalies which result from
defective closure of neural tube early in the fetal life
and anomalous development of the caudal cell mass.
Neural tube defect exact emotional and economic toll
on families and health care systems.
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