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

2. Aims Essential Embryology Introduction to Spinal Dysraphism Types of Spinal Dysraphism Management Strategies Tethered Cord Syndrome Management of TCS 3. 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 4. Essential Embryology 1. Formation of Neural Tube 5. Embryology contd. Neural Folds Neural Crest Neural Groove Somites 6. Embryology contd. 7. Embryology contd. Anterior neural pore Posterior neural pore failure to close = anencephaly failure to close = spina bifida 8. Embryology contd. Neural crest becomes peripheral nervous system (PNS) Neural tube becomes central nervous system (CNS) Somites become spinal vertebrae. Somites 9. 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) 10. 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 11. 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 12. 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 13. 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 14. 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 15. Classification (contd.) 1. Open Spinal Dysraphism (95%) Myelomeningocele Myelocele Hemimyelomeningocele Hemimyelocele 16. 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 17. 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 18. 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 19. Surgical Management To treat or not to treat? Improving the quality of life Effectiveness of early and aggressive intervention John Larbors 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 20. 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 21. 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 22. Surgical Technique 23. 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 24. 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 25. 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 26. 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 27. 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 28. 0 10 20 30 40 50 60 Signs associated with Occult Spinal Dysraphism 29. Fauns hairy tail 30. Foot ulcers 31. 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 32. Lipomyelomeningocele 33. Lipomyelomeningocele 34. 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., fauns tail (but not specific) May be associated with scoliosis 35. Diastematomyelia / Diplomyelia 36. 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 37. 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 38. 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 39. Surgical Technique 40. 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 41. 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 42. Congenital Dermal Sinus 43. 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 44. 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 45. 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 46. References 1. Group MRCVRS. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991;338(8760):131-137. 2. Czeizel AE, Dudas I. Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. N Engl J Med. 1992;327(26):1832-1835. 3. Cochrane D, Wilson R, Steinbok P, et al. Prenatal spinal evaluation and functional outcome of patients born with myelomeningocele: information for improved prenatal counselling and outcome prediction. 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