Neural tube defects
Definition
Abnormalities of development
of the neural tube in utero (fail to close)
ocurring between 3-4 weeks of development
Epidemiology
1/500 UK
95% are spina bifida
or anencephaly
Pathophysiology
Anencephaly
Absence of skull vault and cerebral cortex
Incompatible with life (die within hours of birth)
Spina bifida
Occulta
Mildest form
Split in vertebrae due to failed fusion of cerebral arch, but no cord herniation
Asymptomatic or mild neurological issues due to tethering of cord and trauma during growth
Myelomeningocoele
Severe form
Split in vertebra with herniation of meninges, CSF and cord
Abnormal neurology at/below lesion
Often have hydrocephalus andd abnormal cerebellum
(mental impairment)
Meningocele
Rarest type
Split in vertebra with meninges and CSF herniation
Asymptomatic to moderate neurological issues
Prevention
Folic acid supplementation
400mcg/d for 3m pre-conception to 12wk
5mg/d if high risk (prev NTD, medications)
Diagnosis
Investigations
Mechanism
Failure of fusion of neural plate to form
the neural tube during first 28d of conception
Lesions above L3 most debilitating (bowel, bladder, lower limb)
Lesions belwo L3 likely to dislocate hips (uapposed hip flexors and adductors)
Screening
Antenatal screening programme
Foetal anomaly scan (18-20w)
Detect vast majority of ancephaly
Detect spina bifida depending on severity (absent vertebral body, lemon sign due to frontal bone scalloping, banana cerebellum)
Newborn examination
Patches of pigment/hair on neonate back
Abnormal lower limb tone
Examination
Encephalocoele
Extrusion of brain and meninges via midline skull defect
Compatible with life if early correction
Often associated cerebral malformations
Clinical
presentation
Skin changes
Lumbar region
Tuft of hair, sinus, birth mark, lipoma
Management
Medical
Surgical
Conservative
Information, advice, support
Referral to neurology and neurosurgery
Physiotherapy to prevent joint contractures
OT (walking aids, wheelchairs, house adaptions)
Skin care (sensory loss)
Regular FU (obs, FBC, U+E, urine dipsticks)
Diet (low roughage if bowel neuropathy)
Tethering
Indication: spina bifida occulta with cord tethering
MOA: release cord, allowing growth
without risk of cord damage
Lower limb paralysis
Hypotonia
Lower limb sensory loss
Bladder/bowel issues
Scoliosis
Hydrocephalus
Due to assoc Arnold-Chiari malformation
Prevalence is decreasing in UK
Catheter
Indication: neuropathic bladder
E.g. indwelling catheter or intermittent catheterisation
Laxatives
Indication: neuropathic bowel
Scoliosis repair
Indication: severe scoliosis
VP shunt
Indication: hydrocephalus
Complications
Hip dislocation
Sensory loss
Leg paralysis
Scoliosis
Hydrocephalus
Bladder/bowel incontinence
Development exam
Delayed motor milestones
Neuro exam
Lower limb paralysis/sensory loss
Bladder/bowel incontinence
History
SH
Living arrangements, nursery/school
FH
Neurological disorders, NTDs
DH
Antiolate, teratogenic meds, allergies
POH
Bloods, scans, growth, gestation,
delivery, complications
Previous NTDs
Newborn exam
Hypotonic infant, frog-leg appearance,
lumbar skin changes/hairy patch/dimple
Dislocated hips
Bloods
Genetic screen if suspected syndrome
Imaging
USS: ancephaly has absent cranium, bulging eyes
SB has defect vertebrae/overlying tissue, frontal bone scalloping (lemon sign), abnormal cerebellum (banana sign)
Bedside
Obs