a comprehensive presentation on the subject of spinal dysraphism and spina bifida and its neurosurgical management as well as the management of its various other types

2. Spinal Dysraphism
&
Tethered Cord Syndrome
Dr. Mukhtar
Neurosurgery
Postgraduate Medical Institute, HMC

7. Aims
• Essential Embryology
• Introduction to Spinal Dysraphism
• Types of Spinal Dysraphism
• Management Strategies
• Tethered Cord Syndrome
• Management of TCS

8. Objectives
• At the end of this presentation the audience
will be able to;
– Know the essential spine embryology & its
aberrations
– Appreciate the types of developmental spinal
anomalies & spinal dysraphism
– Understand Neurosurgical management
strategies for spinal dysraphism
– Get an overview of the sequelae of spinal
dysraphism and tethered cord syndrome

9. Essential Embryology
1. Formation of Neural Tube

10. Embryology contd.
• Neural Folds
• Neural Crest
• Neural Groove
• Somites

11. Embryology contd.

12. Embryology contd.
Anterior
neural
pore
Posterior
neural
pore
failure to close =
anencephaly
failure to close =
spina bifida

13. Embryology contd.
• Neural crest becomes
peripheral nervous
system (PNS)
• Neural tube becomes
central nervous system
(CNS)
• Somites become spinal
vertebrae.
Somites

15. Spinal Dysraphism
• Incomplete closure of the neural tube around
third and fourth week of embryonic development
• Combined malformations of the vertebral column
and spinal cord
• Lesions types;
– Spina bifida cystica: closed lesions but outside skin
– Spina bifida aperta: lesions communicating with the
outside
– Spina bifida occulta: concealed, no skin defect
• Recently classified as Open and Closed spinal
Dysraphism (OSD and CSD)

16. Aetiology
• Familial tendency (2.5% vs. 0.2% risk in
general population)1
• Nutritional factors; social class difference in
incidence1,2
• Folic acid use preconception and during
pregnancy1,2,3
• Teratogens e.g., valproate, phenytoin,
alcohol etc3,5,6
• Homeobox and pax3 embryonic genes3

17. Pathogenesis
• Occurs between days 20 to 28 of gestation7
• Failure to close of the neural folds at the caudal
end of neural tube
• Followed by failure of closure of the caudal
somites, resulting in a gap of the spine
• The various varieties of spinal dysraphism are a
result of the time and extent of failure of the
neural tube closure7

18. Pathogenesis (contd.)
• Open Spinal Dysraphism:
– Most common; 95% cases
– A ratio of 9:1 of OSD to CSD
– Vertebral defect with meningeal or spinal cord as the
wall of the extruding cyst
– Almost all OSD are with Chiari II malformation and
Hydrocephalus
– Worst form is Rachischisis; associated with anencephaly
– Diagnosed antenatal or at birth
– Neurologic dysfunction is due to;
• Primary defect in development of the nervous tissue
• Exposure to amniotic fluid
• Injury during birth

19. Pathogenesis (contd.)
• Closed Spinal Dysraphism:
– 5% of cases; occult;
– With or without a subcutaneous mass
– Intact skin covering
– No meningeal or spinal cord cystic lesion
– Most subcutaneous masses are lipomatous
– Usually identified during investigation of urologic,
orthopaedic or dermal and limb problems8

21. Classification
• Spina bifida cystica and aperta  Open
Spinal Dysraphism (OSD)
• Spina bifida occulta  Closed Spinal
Dysraphism (CSD)
• CSD is further subdivided by the presence or
absence of a subcutaneous mass
• Most recent and comprehensive
classification in use was proposed by Tortori-
Donati et al in 2000 9,10

22. Classification (contd.)
1. Open Spinal Dysraphism (95%)
Myelomeningocele
Myelocele
Hemimyelomeningocele
Hemimyelocele

23. Classification11 (contd.)
2. Closed Spinal Dysraphism (5%)
With a
subcutaneous mass
Without a
subcutaneous mass
Cervical  Cervical myelocystocele Simple  Tight filum terminale
Cervical
myelomeningocele
Intradural lipoma
Cervical meningocele Posterior spina bifida
Lumbosacral  Lipomyelomeningocele Complex  Diastematomyelia /
Diplomyelia
Lipomyeloschisis Neurenteric cysts
Dermal sinus
Caudal regression
syndrome
Dorsal enteric fistula

24. Myelomeningocele (MMC)
• Most common spinal birth defect
• Bony defect through which the spinal cord and its
coverings protrude
• Prevalence in Pakistan unknown (estimated at 5-
15/1000 live births)
• Almost all associated with Chiari II malformation
and hydrocephalus (85 – 95%)
• Lumbosacral involvement is the commonest1,2,3,10,11

25. Myelomeningocele (contd.)
• Antenatal diagnosis possible at 14 to 20
weeks
• Ultrasound, serum AFP, amniocentesis for
acetylcholinestrase (accuracy about 90%)
• T2 weighted MRI useful in delineating the
neurological defects antenatally
• Delivery is usually by C-Section
• Surgical Correction of the sac (48-72 hours)
• Management of Hydrocephalus require
special attention

27. Surgical Management
• To treat or not to treat?
– Improving the quality of life
– Effectiveness of early and aggressive intervention
• John Larbor’s Experiment (1970s)
– Withhold extreme measures for those with severe
anomalies
• Medical ethics and individual rights
– The right to health and the right to life is for everyone
– Education of the parents regarding care of the infant
– Role of the treating physician

28. Surgical Management
• Careful clinical assessment
– Spina bifida neurological scale
• Pre-op counseling of the parents regarding
neurological recovery
• Surgery is for prevention of infection & correcting
CSF leak
• Abnormal bladder function persists in most cases
• Lower limbs difficult to assess
– Preservation of L3  ability to stand
– Preservation L4-L5  ability to ambulate

29. Surgical Management
• antibiotics if the surgery has to be delayed
• Nursing in prone position or laterally, keeping the
defect wet with soaked gauze
• Complete excision of zona epitheliosa and
closure of the dural sac and skin is the goal of the
surgery
• Failure to achieve the above, results in inclusion
cysts and tethered cord
• Closure of the normal skin is done along the long
axis of the defect

31. Surgical Technique

32. Post-op care
• Wound complications, shunt malfunction,
hydromyelia, tethered cord or worsening CM II are
the common complication
• Care of the patient with MMC is lifelong requiring
paediatric, urologic, physiotherapic, orthopedic,
neurologic and psychologic support
• Stridor, apnoea and bradycardia are signals of
poor prognosis and a result of advancing CM II
• Hydrocephalus is either treated simultaneously,
before closure of MMC or after clinical appearance

33. Post-op outcome
• Ten to 15% of children die in the first 6 years of
their lives despite aggressive treatment
• 75 to 80% with normal IQ
• Survival:
– 92% survive to 1 year
– 78% to 17 years of age
– 46% to age > 40 years
• It is to be remembered that surgical treatment
aims at reducing disability & death and not the
neurological deficits that has already occurred
• Hydrocephalus and shunt complications tend to
affect intelligence

35. Closed Spinal Dysraphism & Tethered
Cord Syndrome
• Some conditions leading to anatomical tethering
of the cord are;
– Lipomyelomeningcele
– Diastematomyelia and Diplomyelia
– Anterior sacral meningocele
– Myelocystocele
– Dural dermal sinus

36. • Tethering of the cord may result in significant
disabilities and prolonged morbidities
• The leading problems are pain, motor
weakness, urologic issues, dermatologic
manifestations, orthopedic problems and
psychologic sequelae
• These problems occasionally present in
infancy while a majority is diagnosed in late
childhood to early adulthood

37. • All conditions need surgical intervention to
release the cord
• The primary aim of neurosurgical intervention
is to stop further progression and help in
good physical and neuro-rehabilitation
• A multidisciplinary approach and high degree
of clinical vigilance is necessary for diagnosis
• Signs and symptoms are non-specific to any
particular tethering cause

38. 0
10
20
30
40
50
60
Signs associated with Occult Spinal Dysraphism

39. Fauns hairy tail

40. Foot ulcers

41. Lipomyelomeningocele
• derives from the secondary remnant cells of
the notochords’ caudal end
• mature adipose tissue fused to the dorsal
dura and protruding through the spinal defect
• Eventually causes tethering
• Two main types;
– adherent to the dorsal surface of the cord itself
– Adherent to the lower part of conus and filum
• Treatment is laminectomy and untethering of
the cord

43. Lipomyelomeningocele

44. Lipomyelomeningocele

47. Diastematomyelia / Diplomyelia
• Also called Split Cord Malformations
• Caused by duplication of the cord either by an
intervening bony spur or dural septum
• Causes cord tethering and neurological problems
• Incontinence, gait abnormalities, lower limbs pain
and sensory loss in feet
• Associated with midline dermal stigmata, i.e.,
faun’s tail (but not specific)
• May be associated with scoliosis

49. Diastematomyelia / Diplomyelia

50. Diastematomyelia / Diplomyelia
• Two types;
– Split cord with an intervening bony spur
– without bony spur
• Female preponderance
• MRI is the confirming investigation
• Treatment is laminectomy, followed by excision of
the bony spur and repair of dura
• There is small risk of neurologic deterioration post-
operatively which should be communicated to the
patients / parents

51. Anterior Sacral Meningocele
• Evagination of meningeal sac anteriorly into the
pelvic cavity through a defect in the sacrum
• Rare cause of cord tethering
• Usually found accidentally on DRE or investigations
for pelvic pathology/ rarely during a laparotomy
• Any breach of the meningeal wall may increase the
risk of meningitis

52. Anterior Sacral Meningocele
• Pelvic ultrasound, CT myelography or MRI are
useful investigations
• Treatment is surgical reduction of the meningeal
sac and closure of the defect some times with a
fascial patch
• A posterior sacral laminectomy is the preferred
approach
• Division of filum terminale is essential step for
untethering

53. Surgical Technique

54. Congenital Dermal Sinus
• A tubular connection between the skin surface
where the channel may end subcutaneously,
interspinous area, inside the spinal canal,
intradurally or intramedullary cystic extension
• This type of sinus may easily be mistaken with a
pilonidal sinus
• Differentiation is done by the dimple created by the
tethered overlying skin which is not the case in
pilonidal sinus

55. Congenital Dermal Sinus
• Treatment is by complete dissection of the sinus
tract and its excision in toto followed by water tight
closure of the dura and releasing the tethering
elements
• Extensive laminectomy is required in some cases
• Filum terminale is usually divided in the wake of
untethering of the cord

57. Congenital Dermal Sinus

58. Surgical Management of TCS
• Tethered cord syndrome needs surgical correction
• The neurologic deterioration is improved in majority
of cases postoperatively
• A small risk of neurological deterioration still persist
even in experienced hands
• Almost all types of tethering lesions require removal
of the tethering elements and release of the spinal
cord
• All operated cases of MMC do have cord tethering,
but needs careful assessment before being labelled
as TCS

60. Recent Advancements
• Foetal MMC repair is an advancing development
but no definitive data exists
• Results are favourable in decreasing neurologic
deficits and reducing the occurrence of CM II and
hydrocephalus
• No final consensus or guidelines; still experimental
• Issues of medical ethics; issue of two individuals

61. Pearls
• periconceptional folate results in a 72%
relative risk reduction in the recurrence of
spina bifida in subsequent children
• periconceptional folic acid intake results in a
42% relative risk reduction in the incidence
of first occurrence of spina bifida
• In patients with lumbosacral dimples, US
exam is more cost effective than MRI in
screening for occult spinal dysraphism
• the anomaly could not be eradicated due to
its multifactorial nature

62. References
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63. Gracias muchias!