1. Spinal Dysraphisms- Congenital Spinal Cord Abnormalities
C Herman, J Ponting, I Wu
Indiana University School of Medicine
Presentation # eEdE-198

2. No disclosures

3. Abstract
Purpose:
Spinal dysraphisms consist of a very wide range of pathologies and imaging appearances, some of which can be particularly challenging for radiologists and clinicians who primarily deal with adult patients. To simplify these potentially confusing congenital anomalies, spinal dysraphisms can be generally divided into two major categories - open and closed types.
This electronic educational presentation will provide an overview of the imaging appearance of both open and closed type spinal dysraphisms. Imaging examples of each type will be provided to reinforce the spectrum of congenital abnormality that can be diagnosed, particularly on MRI. Also, image examples of spinal dysraphisms on fetal MRI will also be provided, which has become an increasing indispensable imaging modality to make early diagnosis of congenital anomalies in utero.
Approach/Methods:
Imaging studies from patients with congenital abnormalities of the spine and spinal cord are identified from a large tertiary referral center by retrospective case review. Of these, a wide range of cases is selected that represent the appearance of a majority of spinal dysraphisms, including multiple examples of fetal MRIs. From these cases, a PowerPoint presentation is generated focusing on the imaging appearance of each type of congenital abnormality and providing an organized approach to various open, closed and segmentation anomalies.
Findings/Discussion:
After viewing this presentation, the viewer will have greater familiarity with the appearance of spinal dysraphisms and be better equipped to diagnose these congenital abnormalities based on the organized approach provided.
Summary/Conclusion:
Congenital spinal cord and spinal abnormalities can be a complex topic for many radiologists. By reviewing this exhibit, the viewer will become more familiar with the appearance of spine dysraphisms, leading to a more organized approach to this spectrum of abnormalities.

4. Overview of Classification
Open spinal dysraphisms
Closed spinal dysraphisms
With subcutaneous mass
Without subcutaneous mass
Simple dysraphic states
Complex dysraphic states (including segmentation anomalies)

5. Open Spinal Dysraphisms
Types:
Myelomenigocele
Myelocele
Defect in overlying skin causing exposure of neural tissue
Neural placode protrudes through a midline skin defect
Caused by incomplete closure of the neural tube

6. Open Spinal Dysraphisms
Myelomeningocele
Neural placode protrudes above the skin surface
Neural tissue, CSF and meninges are displaced
Failure of neural tube closure
T1 shows wide spinal dysraphism
98% of open dysraphisms
Frequently associated with other CNS abnormalities
Lumbosacral most common
Myelocele
Axial T2
Sagittal T2
4-day-old boy with a low lying cord and herniation of the spinal cord, nerve roots and CSF sac dorsally through a spinal dysraphism

7. Cervicothoracic myelomeningocele
Axial T2
Sagittal STIR
Sagittal T2
Spinal cord and cerebellar tonsils protruding through a wide posterior spinal dysraphism

8. Open Spinal Dysraphisms
Myelomenigocele
Myelocele
Neural placode flush with skin
Compared to protrusion above the skin as seen in myelomeningoceles
Caused by defective closure of the primary neural tube
Very rare
Less than 2% of open spinal dysraphisms

9. Closed Spinal Dysraphisms
Neural tissue covered by skin
With subcutaneous mass:
Lipomas with dural defect
Meningocele
Myelocystocele
Without subcutaneous mass:
Simple dysraphic states
Complex dysraphic states
Disorders of midline notochord integration: dorsal fistula and neurenteric cyst
Diastatematomyelia
Disorders of notochord formation: caudal agenesis
Segmental spinal dysgenesis

10. Closed Spinal Dysraphisms
Neural tissue covered by skin
With subcutaneous mass:
Lipomas with dural defect
Meningocele
Myelocystocele
Without subcutaneous mass:
Simple dysraphic states
Complex dysraphic states
Disorders of midline notochord integration: dorsal fistula and neurenteric cyst
Diastatematomyelia
Disorders of notochord formation: caudal agenesis
Segmental spinal dysgenesis

11. Closed Spinal Dysraphisms with subcutaneous mass
Lipoma with dural defect
Disorder of primary neurulation where mesenchymal tissue enters the neural tube and forms fatty tissue (lipoma)
Clinically seen as a subcutaneous fatty mass above the intergluteal crease
Types:
Lipomyelocele
Lipomyelomeningocele
Meningocele
Myelocystocele

12. Closed Spinal Dysraphisms with subcutaneous mass
Lipoma with dural defect
Lipomyelocele
Low lying spinal cord adheres to a large lipoma that extends through a posterior spinal dysraphism
Placode-lipoma complex is contiguous with subcutaneous fat
Lipomyelomeningocele
Meningocele
Myelocystocele
Intraspinal lipoma associated with the distal spinal cord (noted to be low lying, extending to the L4 level) and continuous with the subcutaneous fat through a posterior sacral bony defect at the S3 level.

13. Lipomyelocele
Axial T1 images showing an intraspinal lipoma associated with the distal spinal cord that is continuous with the subcutaneous fat through a posterior sacral bony defect at the S3 level.

14. Closed Spinal Dysraphisms with subcutaneous mass
Lipomas with dural defect
Lipomyelocele
Lipomyelomeningocele
Lipomyelocele + myelomeningocele
Lipoma associated with the spinal cord and contiguous with subcutaneous fat
Protrusion of thecal sac, nerve roots and spinal cord through dysraphic posterior elements
Spinal cord is always tethered
Meningocele
Myelocystocele
Sagittal T1

15. Lipomyelomeningocele
Sagittal T1
Axial T1
Axial T1
72-day-old boy with low-lying conus (tethered cord), spinal cord mass with predominately fat signal (lipoma) contiguous with the subcutaneous fat. The mass also has associated CSF and soft tissue signal.

16. Closed Spinal Dysraphisms with subcutaneous mass
Lipomas with dural defect
Meningocele
Herniation of CSF-filled sac lined by dura and arachnoid through an osseous defect of the posterior spinal elements (spina bifida)
Does NOT contain spinal cord
Compared to myelomeningocele
Lumbar and sacral most common
Myelocystocele
Sagittal SSFSE
Axial SSFSE
Fetal MRI showing L5-S1 spinal dysraphism with likely associated meningocele

17. Fetal MRI: Thoracic Meningocele
Sagittal TruFisp
Axial Haste
Protrusion of a CSF filled sac through a thoracic dysraphism on fetal MRI completed at weeks.

18. Same patient at 1 day old: Thoracic Meningocele
Sagittal T2
Axial T2
Protrusion of a CSF filled sac through a thoracic dysraphism, similar in appearance compared to the fetal MRI.

19. Closed Spinal Dysraphisms with subcutaneous mass
Lipomas with dural defect
Meningocele
Myelocystocele
Dilated central spinal canal (inner cyst) protruding through posterior dysraphic spine into dilated subarachnoid space (outer cyst) in subcutaneous location
Caused by incomplete fusion of dorsal neural folds
Terminal myelocystocele: herniation of terminal syrinx into posterior meningocele
Sagittal T2
8-month-old girl with a tethered spinal cord and myelocystocele.

20. Closed Spinal Dysraphisms
Without subcutaneous mass:
Simple dysraphic states
Complex dysraphic states

21. Closed Spinal Dysraphisms without subcutaneous mass
Simple dysraphic states
Intradural lipoma
filar lipoma
tight filum terminale
persistent terminal ventricle
dermal sinus

22. Closed Spinal Dysraphisms without subcutaneous mass
Simple dysraphic states
Intradural lipoma
Lipoma within the dural sac at the dorsal midline
Lumbosacral most common
Typically present with tethered-cord syndrome: progressive neurologic abnormalities in the setting of traction on low-lying conus
filar lipoma
tight filum terminale
persistent terminal ventricle
dermal sinus

23. Intradural Lipoma
Sagittal T1
Sagittal T2
3-month-old boy with a fat signal lesion in the posterior spinal canal compatible with intradural lipoma. The conus is tethered to the lipoma and low-lying.

24. Closed Spinal Dysraphisms without subcutaneous mass
Simple dysraphic states
Intradural lipoma
filar lipoma
Fibrolipomatous thickening of the filum terminale
Hyperintense strip of signal on T1 with thickening of filum
Normal variant if no tethered-cord syndrome
tight filum terminale
persistent terminal ventricle
dermal sinus
Coronal T1

25. Filar Lipoma
Sagittal T1
Sagittal T1 FS +C
32-month-old girl with hyperintense signal along the filum terminale on T1WI that shows signal drop out on post-contrast fat-saturated T1WI.

26. Closed Spinal Dysraphisms without subcutaneous mass
Simple dysraphic states
Intradural lipoma
filar lipoma
tight filum terminale
Hypertrophy of the filum terminale
Can cause tethering and low lying conus (normal above L2-L3)
persistent terminal ventricle
dermal sinus
Sagittal T2
5-year-old girl with thickened filum terminale conus at L2-L3.

27. Closed Spinal Dysraphisms without subcutaneous mass
Simple dysraphic states
Intradural lipoma
filar lipoma
tight filum terminale
persistent terminal ventricle
Small ependymal lined cavity in conus located immediately above filum terminale
Nonenhancing dilation of the central spinal canal in the conus
dermal sinus
Axial T2

28. Closed Spinal Dysraphisms without subcutaneous mass
Simple dysraphic states
Intradural lipoma
filar lipoma
tight filum terminale
persistent terminal ventricle
dermal sinus
Epithelial lined fistula connecting the neural tissue or meninges to the skin
Can lead to infection
Lumbosacral most common
Often associated with a spinal dermoid
Sagittal T2
Dorsal dermal dermal sinus extending into the thecal sac at the S1-S2 level

29. T1
T1 C+ T2 T2
10-year-old with a dorsal dermal sinus and associated intramedullary dermoid (characteristic well circumscribed appearance with partial diffusion restriction).
DWI
ADC
T1 C+

30. Dorsal Dermal Sinus
Dorsal dermal sinus tract communicating with an intradural lipoma through a defect in the posterior spine in a 3-month-old boy with a sacral dimple

31. Closed Spinal Dysraphisms without subcutaneous mass
Complex dysraphic states
Disorders of midline notochord integration
neurenteric cyst
diastatematomyelia
Disorders of notochord formation
caudal agenesis
Segmental spinal dysgenesis

32. Closed Spinal Dysraphisms without subcutaneous mass
Complex dysraphic states
Disorders of midline notochord integration
neurenteric cyst
Intraspinal cyst lined by mucin-secreting enteric mucosa
Caused by failure of separation of dorsal ectoderm (spinal cord) and ventral endoderm (foregut)
Iso- to hyperintense to CSF on T1 depending on mucin content
diastatematomyelia
Disorders of notochord formation
caudal agenesis
Segmental spinal dysgenesis
Sagittal T1

33. Neurenteric Cyst: Craniovertebral Junction
Sagittal T2
Axial T2
Intradural neurenteric cyst at the craniovertebral junction with a sinus tract extending ventrally

34. Closed Spinal Dysraphisms without subcutaneous mass
Complex dysraphic states
Disorders of midline notochord integration
neurenteric cyst
Diastatematomyelia
Separation of spinal cord into two hemicords
Usually symmetric with variable length of separation
Type 1- individual dural tubes separated by osseous or cartilaginous septum
Type 2- single dural tube with two hemicords, sometimes intervening fibrous septum
Disorders of notochord formation / secondary neurulation
caudal agenesis
Segmental spinal dysgenesis
Soft Tissue Window
Bone window
17-month-old boy with splitting of the thoracic spinal cord by an intervening bony septum (type 1).

35. Diastatematomyelia: type 2
Axial T1
Axial T2
Axial T1 T7 T7 L3
19-month-old boy with splitting of the spinal cord at the T7 level. The spinal cord rejoins into a single structure at the L3 level and is contained within a single dural sac.

36. Closed Spinal Dysraphisms without subcutaneous mass
Complex dysraphic states
Disorders of midline notochord integration
neurenteric cyst
diastatematomyelia
Disorders of notochord formation / secondary neurulation
Caudal agenesis
Total or partial agenesis of the spinal column
Can be associated with anal imperforation, renal and genital anomalies, pulmonary hypoplasia and limb abnormalities
Segmental spinal dysgenesis
Newborn boy with multiple anomalies including absence of the spine from the mid-thoracic level caudally.

37. Caudal Agenesis
Sagittal T2
Coronal CT
21-year-old woman with abnormal termination of the spinal cord at T10-11 and associated complete absence of the sacrum.

38. Closed Spinal Dysraphisms without subcutaneous mass
Complex dysraphic states
Disorders of midline notochord integration
neurenteric cyst
diastatematomyelia
Disorders of notochord formation
caudal agenesis
Vertebral segmentation anomalies
Various appearances
CT helpful
17-year-old woman with a fusion anomaly at the lumbosacral junction

39. Vertebral Segmentation Anomalies
8-year-old girl with scoliosis and a partial sagittal partition segmentation anomaly at T7.

40. Vertebral Segmentation Anomalies
75-day-old boy with vertebral anomalies including multiple hemivertebrae.

41. Vertebral Segmentation Anomalies
Radiograph
Coronal CT
3D reformat CT
Coronal T2
T3 butterfly vertebra on multiple imaging modalities.

42. Summary of Classification
Open spinal dysraphisms: defect in skin exposing neural tissue
Closed spinal dysraphisms: neural tissue covered by skin
With subcutaneous mass
Without subcutaneous mass
Simple dysraphic states
Complex dysraphic states (including segmentation anomalies)

43. Sources
Adzick NS: Fetal myelomeningocele: natural history, pathophysiology, and in-utero intervention. Semin Fetal Neonatal Med. 2010; 15(1): 9-14.
Aydin AL et al: Prenatal diagnosis of a large, cervical, intraspinal, neurenteric cyst and postnatal outcome. J Pediatr Surg. 2009; 44(9):
Muthukumar N: Terminal and nonterminal myelocystoceles. J Neurosurg. 2007; 107(2 Suppl):87-97.
Rufener, SL, Ibrahim M, Raybaud, CA, Parmar, HA. Congenital spine and spinal cord malformations- pictoral review. American Journal of Roentgenology. 2010; 194: S25-S37.
Tortori-Donati P et al: Spinal dysraphism: a review of neuroradiological features with embryological correlations and proposal for a new classification. Neuroradiology. 2000; 42(7):