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Neural tube defect
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- 2. Definition • Dysraphism • Groupof disorder • Resulting from failure of closure embryonic posterior and anterior neuropores • Associated with abnormal development of other part of neural tube and bony & soft tissue structures • Most congenital anomalies of the CNS • Incidence is declining • Folic acid supplementation • Earlier prenatal diagnosis
- 3. Etiology • Hyperthermia • Drugs •Malnutrition • Maternal obesity or DM • Genetic : mutation at the folate responsive and folate dependent pathway • Exposure to radiation before conception
- 4. Types • Spina bifidaocculta • Meningocele (cystica) • Myelomeningocele (cystica) • Encephalocele • Anencephaly • Others
- 5. Spina bifida occulta •Defect in closure of posterior vertebral arches and laminae,usually occur at L5 and S1,and no protrusion of spinal cord or meninges • Clinical features • Asymptomatic and lack of neurological signs • Cutaneous manifestation : haemangioma,dimple,lump or hairy patch
- 6. Meningocele (cystica) • Meningesherniates through a posterior vertebral arches (normal spinal cord • Mostly covered with skin : less meningitis • Anterior meningoceles project into the pelvis through a defect at the sacrum • Constipation • Bladder dysfunction • Investigations • Plain reontgenogram,US and MRI : extent of neural tissue involvement • CT scan of the head : any concomitant presence of hydrocephalus • Management • Surgery : delayed in normal neurological development,thick skin covering meningocele and immediate leaking of CSF,thin skin (to prevent meningitis) • Surgical referral of female : associated with anomalies of genital tract (rectovaginal fistula,anorectal septa)
- 7. Myelomeningocele (cystica) • Spinalcord and meninges protrude through the vertebral arch (most severe form of NTD) • Dysfunction of many organ and structures along the neural axis but lumbasacral region (75%) affected: • Peripheral NS • Skeleton • Skin • GIT • Genitourinary tract • Hydrocephalus occur in associated with type II Chiari-Malformation
- 8. Meningomyelocele • Low sacralregion • Bowel and bladder incontinence • Anesthesia of perianal area • No impairment of motor function • Mid lumbar region (abnormality and disruption of conus medularis) • Flaccid paralysis of LL • Absence deep tendon reflexes • Lack response to touch and pain • Deformities:clubfeet,subluxation of the hip • Constant urinary dribbling and a relaxed anal sphincter • High pressure bladder and sphincter dyssynergy
- 9. Meningomyelocele • Treatment • Surgery •Repair defect,shunt the hydrocephalus,early surgical decompression of medulla and cervical cord(if sign and symptoms of hindbrain dysfunction occur) • Regular cathetherized neurogenic bladder • Bowel trained • With regimen of timed enema or suppositories • At a predetermined time • Once/twice per day
- 10. Encephalocele • Part ofbrain and meninges herniated through congenital,traumatic or post surgical defect • Cranial encephalocele : sac,cerebral cortex,cerebellum or portion of brainstem • Most common is occipital > frontal > nasal • Increased risk of • Hydrocephalus (aqueduct stenosis) • Chiari malformation • Dandy Walker syndrome • Visual problems • Microcephaly • Mental retardation • Seizures
- 11. Anencephaly • Large defectof the cavalrium,meninges and scalp associated with rudimentary brain (failure of closure of rostral neuropore) • Absent cerebral hemispheres and cerebellum – residue of the brainstem can be identified • Hypoplastic pituitary gland and spinal cord pyramidal tracts • Anomalies of ear,cleft palate and congenital heart defect • Causes : low socioeconomic status,nutritional and vitamin deficiencies,environmental factors • Die within several day of birth
- 12. Others • Dermal sinus •Tethered cord • Syringomyelia • Diastematomyelia • Lipoma of conus medullaris