SPINAL DYSRAPHISM

1. ANOMALIES OF SPINE AND SPINAL
CORD
DR NIHAL AHMED
Moderator – DR
SIDDHARTH

2. CONGENITAL SPINAL
ANOMALIES
SPINAL DYSRAPHISMS CAUDAL SPINAL
ANOMALIES
Diagnosed –
 Prenatally
 At birth
 Early childhood
 Adulthood

3. IMAGING MODALITIES
MRI – IOC
PLAIN RADIOGRAPH –
 BONY DEFECTS
SCOLIOSIS
BONY SPUR
SEGMENTATION ANOMALIES – BLOCK VERTEBRA
USG – ANTENATAL DIAGNOSIS –MENINGOMYELOCELE SAC,
HYDROCEPHALUS
CT 0- BONY SPUR

4. SPINAL CORD DEVELOPMENT
1. GASTRULATION – 2nd or 3rd WEEK
Formation of the trilaminar disk
2. PRIMARY NEURULATION - 3-4 WEEKS
Notochord and overlying ectoderm interact to form the neural plate.
Neural plate folds and bends forming the neural tube – closes
zipperlike manner
3. SECONDARY NEURULATION – 5-6 WEEKS
Secondary neural tube formed by caudal cell mass- initially solid
followed by cavitation by process called retrogressive differentiation
forms conus medullaris and filum terminale.

5. GASTRULATION

6. PRIMARY NEURULATION
 FORMATION
 SHAPING
 BENDING
 FUSION

7. SECONDARY NEURULATION
CANALIZATION
AND
RETROGRESSIVE
DIFFERNTIATIO
N

8. CLASSIFICATION OF SPINAL
DYSRAPHISMS

9. TERMINOLOGY
Spina Bifida
•Synonym for spinal
dysraphism
•Defective fusion of the
posterior elements.
•Aperta = OSD
Occulta= CSD
Placode
Segment of flattened, non
neurulated embryonic
neural tissue.
Tethered Cord
Syndrome
• Not malformation
• Occur as part of
lipomyelomeningocele,
tight filum terminale,
diastematomyelia
• Limited spinal cord
movement leading due to
abnormal tissue
attachments.
• The clinical picture
involves :-
motor and sensory
dysfunction,
muscleatrophy, decreased or
hyperactive reflexes, urinary
inconti-nence, spastic gait.

10. OPEN SPINAL DYSRAPHISMS
•Exposure of covering neural tissue/meninges through midline defect
in the back
•99% are myelomeningoceles.
•Clinical picture includes sensorimotor deficits of the lower
extremities, bowel and bladder incontinence, hindbrain dysfunction,
intellectual and psychological disturbances.
•Because neurulation does not occur, the cutaneous ectoderm does
not detach from the neural ectoderm and remains in a lateral
position. This results in a mid-line skin defect.
•Role of MRI – presurgical evaluation and look for associated
anomalies – SURGICAL EMERGENCY
•MC LOCATION – Lumbosacral

11. MYELOCELE MYELOMENINGOCELE
Neural placode
protrudes above
the skin surface
Placode is
flush with
skin surface
There is no
expansion of
underlying
subarachnoi
d space.
HEMIMYELOCELE AND HEMIMYELOMENGICELE – associated with diastematomyelia
and one hemicord fails to neurulate.

12. MENINGOMYELOCELE
MYELOCELE

13. CHIARI MALFORMATIONS

14. CHIARI I
Sagittal T1 weighed image shows
tonsillar ectopia (arrow). Posterior
fossa is small.
Axial T1 weighed image showing
crowding of the foramen magnum
due to tonsils (T).

15. CHIARI
II
CHIARY II WITH HYDROMYELIA
Sagittal images very small
posterior cranial fossa and the
typical cascade of herniations
constituting the hallmark of
the Chiari-II malformation.

16. CHIARI III CHIARI IV
CHIARI II + CEPHALOCELE SEVERE
CEREBELLAR HYPOPLASIA
+MYELOMENINGOCELE

17. CLOSED SPINAL DYSRAPHISMS
WITH A SUBCUTANEOUS MASS
Lipoma with dorsal defects
Myelocystocele(Terminal or cervical)
Meningocele

18. LIPOMAS WITH DURAL DEFECT :
LIPOMYELOCELE
AND LIPOMYELOMENINGOCELE
THESE ABNORMALITIES RESULT FROM A DEFECT IN
PRIMARY NEURULATION WHEREBY MESENCHYMAL
TISSUE ENTERS THE NEURAL TUBE AND FORMS
LIPOMATOUS TISSUE.

19. C/F : subcutaneous fatty
mass above the gluteal
crease.
Diff both based on
lipoma – placode
interface
Lipomyelocele :
placode-lipoma interface
within spinal canal.
Lipomyelomenigocele:
Outside the spinal canal
due to sub-arachnoid
space expansion.

20. Lipomyelomeningocele. Axial
schematic of lipomyelomeningocele shows
placode–lipoma interface (arrow) lies
outside of spinal canal due to expansion
of subarachnoid space.
Lipomyelomeningocele. Axial T1-weighted
MR image in
18-month-old boy shows
lipomyelomeningocele (arrow)
that is differentiated from lipomyelocele by
location of
placode–lipoma interface outside of spinal

21. TERMINAL MYELOCYSTOCELE
Herniation of large
terminal syrinx
(syringocele) into a
posterior meningocele
through a posterior spinal
defect is referred to as a
terminal .
The terminal syrinx and
meningocele components
do not usually
communicate with each
other.
MYELOCYSTOCELE(N
TERMINAL)
Dilated central canal
herniates through a
posterior spina bifida
defect.
covered with skin
MC -cervical or
cervicothoracic regions

23. Schematic
of nonterminal
myelocystocele shows
herniation of dilated
central canal through
posterior spinal defect
MC -cervical or
cervicothoracic
regions

24. 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 .
2 types…
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 elsewhere

25. ANTERIOR MENINGOCELE

26. CLOSED SPINAL DYSRAPHISMS
WITHOUT A SUBCUTANEOUS MASS
Simple dysraphic states
intradural lipoma,
filar lipoma,
tight filum terminale,
persistent terminal ventricle
dermal sinus.
Complex dysraphic states be
divided into two categories:
A) disorders of midline
notochordal integration,
dorsal enteric fistula,
neurenteric cyst, and
diastematomyelia,
B)disorders of notochordal
formation,
caudal agenesis and
segmental spinal dysgenesis

27. LIPOMA
2 Types : Intradural lipoma and Filar lipoma
Embryological defect : focal premature disjunction of epidermal from neural
ectoderm.
INTRADURAL LIPOMA
Lipoma within the dural sac
MC : Lumbosacral spine
a/w tethered-cord syndrome
FILAR LIPOMA
Fibrolipomatous thickening of the filum terminale is referred to as a filar
lipoma.
MR : T1 hyperintense signal + thickened filum terminale

28. Diagrammatic representations of
spinal lipomas. A: Intradural
lipoma.
The pia-arachnoid encloses
the spinal cord and the lipoma.
The lipoma lies predominantly
within a midline cleft in the
dorsal spinal cord but fungates
beneath the pia to bulge into the
dorsal subarachnoid space.
B: Lipomyelocele.
C: lipomyelomeningocele.
BOTH ANOMALIES OF
PRIMARY NEURULATION

29. INTRADURAL
LIPOMA
Sagittal T1-weighted (A) and sagittal T2-
weighted fat-saturated (B) MR images show
Large intradural lipoma (arrows), which is
hyperintense on T1-weighted image and
hypointense
on T2-weighted fat-saturated image. Lipoma
is
attached to conus medullaris, which is low
lying.

30. FILAR LIPOMA
Sagittal (A) and
axial (B) T1-
weighted MR
images I shows
filar lipoma
(arrows),
which has
characteristic T1
hyperintensity and
marked thickening
of filum terminale

31. SIMPLE DYSRAPHIC STATES
TIGHT FILUM TERMINALE
hypertrophy and shortening of the
filum terminale.
EMBRYOLOGY : incomplete
involution of the distal spinal cord
during embryogenesis.
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(above the L2–L3 disk level).

32. 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.

33. SIMPLE DYSRAPHIC STATES
TERMINAL VENTRICLE
Persistence of a small, ependymal
lined cavity within the conus
medullaris is referred to as a
persistent terminal ventricle .
It appears to represent the point of union
between primary and secondary neural tube.
Key imaging features include
lack of contrast enhancement, which differentiate
this entity from other cystic lesions
of the conus medullaris.

34. 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.

35. SIMPLE DYSRAPHIC STATES
DERMAL SINUS
Epithelial lined fistula that
connects neural tissue or
meninges to the skin surface.
If the superficial ectoderm
fails to separate from the
neural ectoderm at one point.
MC : Lumbo sacral region
C/F : midline dimple , hairy
naevus , hyperpigmented
patch /capillary hemangioma
Infectious complication if not
surgically treated

37. COMPLEX DYSRAPHIC STATES
DISORDERS OF MIDLINE
NOTOCHORDAL
INTEGRATION
Dorsal enteric fistula,
Neurenteric cyst
Diastematomyelia,
Caudal agenesis
Segmental spinal
dysgenesis.
DISORDERS OF
NOTOCHORDAL
FORMATION

38. DISORDERS OF MIDLINE NOTOCHORDAL
INTEGRATION
DORSAL ENTERIC FISTULA
Abnormal connection between the skin
surface and bowel.
NEURENTERIC CYSTS
Localized form of dorsal enteric fistula
Mucin-secreting epithelium (~GI tract )
lined cyst
MC : cervico-thoracic spine anterior to
spinal cord

39. SAGITTAL T2-
WEIGHTED (A)
AND AXIAL T1-
WEIGHTED
(B)MR IMAGES
SHOW
BILOBED
NEURENTERIC
CYST (ARROWS)
EXTENDING
FROM CENTRAL
CANAL INTO
POSTERIOR
MEDIASTINUM.

40. DISORDERS OF MIDLINE
NOTOCHORDAL INTEGRATION
DIASTEMATOMYELIA
Separation of the spinal cord into two hemicords.
The two hemicords are usually symmetric, although the
length of separation is variable.
Type 1 : Dual Dural-Arachnoid Tubes (Pang Type I) :
the two hemicords are located within individual dural
sacs separated by an osseous or cartilaginous septum
Type 2 : Single Dural-Arachnoid Tube (Pang Type II) :
Single dural tube containing two hemicords, sometimes
with an intervening fibrous septum
C/F : Hairy tuft , scoliosis , tethered cord syndrome.

41. posterior view of the patient reveals
the large patch of
long, silky hairs
overlying diastematomyelia and a
small sacral dimple.
Embryogenesis of split notochord syndrome

42. 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 .

43. TYPE 2 DIASTEMATOMYELIA
Coronal T1- -weighted
(A),
weighted (A), and axial
T2-weighted (B)
MR images show
Splitting of distal cord
into two hemicords
(white arrows) within
single dural tube,
which
is characteristic for
type 2.
Incidental : filum

44. DISORDERS OF NOTOCHORDAL
FORMATION
CAUDAL AGENESIS
Total or partial agenesis of the spinal column
A/w anal imperforation, genital anomalies,
renal dysplasia or aplasia, pulmonary
hypoplasia, or limb abnormalities.
2 Types
Type 1 : high position of conus + abrupt
termination of conus medullaris(D11/12)+
neuro deficit
Type II : low position(L1) + tethering of conus
medullaris

45. Sagittal T2-weighted (A) and
sagittal T1-
weighted (B) MR images in show
Type 1 caudal agenesis. Conus
medullaris is high in position and
wedge shaped (arrow) due to
abrupt termination.
INCIDENTAL -Distal cord syrinx
(arrowhead).

46. CAUDAL REGRESSION
SYNDROME
Partial agenesis of the thoracolumbosacral
spine
Imperforate anus
Malformed genitalia
Bilateral renal dysplasia or aplasia
Pulmonary hypoplasia
Extreme external rotation and fusion of the
lower
extremities (sirenomelia)
Sacral agenesis arises early in gestation,
probably
before the 10th week of gestation

47. DISORDERS OF NOTOCHORDAL
FORMATION
SEGMENTAL SPINAL DYSGENESIS
Segmental agenesis or dysgenesis of the
thoracic or lumbar spine + segmental
abnormality of the spinal cord/nerve roots +
congenital paraparesis / paraplegia, +
congenital lower limb deformities.
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.

48. DEVEOPMENT OF VERTEBRAL
COLUMN
Formed form the sclerotome of somites
Sclerotome converts to loose mesenchyme (4TH WEEK)
It surrounds the notochord – forming the CENTRUM.
Extend to either side of neural tube and
surrounds it – forming the NEURAL ARCH.
Lateral extension from centrum- form transverse process
Notochord disappears in the region of vertebral
body.
In the region of the vertebral discs , it expands
and forms nucleus pulposus.

49. STAGE OF CHONDRIFICATION
6th week
2 centers of chondrification in each
Centrum appear
Fuse together at the end of embryonic period
(8th week) form cartilaginous centrum.
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
of embryonic period
one in the centrum
one for each neural arch
The arches articulate with the centrum at
cartilaginous neurocentral joints.
Bony halves of the vertebral arch fuse together during
the first 3 to 5 years

50. Secondary ossification center
Time of development: after puberty
the 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
FATE OF NOTOCHORD
Cranial part: merged with basilar part of occipital bone
& posterior part of body of sphenoid
Notochord located in the vertebra undergo
degeneration and disappear
The ones located in between undergo mucoid
degeneration to form nucleus pulposus

51. Schematic drawing depicting the development of normal and abnormal vertebral
bodies

52. ASOMIA(agenesis)
• Complete absence of body
of vertebra
• Posterior elements present
• FAILURE OF
OSSIFICATION CENTERES
TO APPEAR
HEMIVERTEBRA
U/L Wedge Or Lateral Vertebrae :
lack of ossification of one half of body.
Scoliosis results
Dorsal Or Ventral Hemivertebrae:
failure of ventral /dorsal half to ossify.
Kyphosis results
(A) Left hemivertebra
involving T11
(B) Dorsal
hemivertebra
involving L1

53. BUTTERFLY
VERTEBRA
Failure of fusion of
lateral halves of the body
Due to persistent
notochordal tissue
May be a/w spinabifida
and anterior
meningocele
CORONAL
CLEFT
Failure of fusion of
anterior and
posterior
ossification centres
Seperated by a
cartilage
plate

54. BLOCK VERTEBRA
(A) Block vertebra with
congenital fusion of C4 and
C5
Note the presence of a “waist”
at the site of fusion (arrow).
(B) Acquired vertebral body
fusion
of C5 and C6
Failure of segmentation
most often in
midthoracic or
thoracolumbar regions
and may involve 2-8
levels.