SPINA BIFIDA

•	Neural tube defects.
•	Clinical features. 
•	Complications of myelomeningocele.
•	History.
•	Clinical examination.
•	Investigations.
•	Management.

Neural Tube Defects

1.	Pathogenesis

a.	The neural tube is the embryological structure from which the brain and the spinal cord develop.

b.	The human neural tube closes just before the 30th day post-fertilization.

c.	Neural tube defects, therefore, result from the defective closure of the caudal neuropore towards the end of the 4th week of development.

d.	There is a high incidence of gross and microscopic brainstem, cerebellar and cerebral malformations.

e.	Severe neural tube defects also involve the tissue overlying the spinal cord, e.g. meninges, vertebral arch, dorsal muscles and skin.

2.	Epidemiology

a.	NTDs are amongst the most common birth defects.

b.	Incidence:

i.	spina bifida cystica: 1 – 2 / 1000 live births.

ii.	spina bifida occluta: 5% of population.

d.	They exhibit a marked geographical variation, with the incidence higher in England and lower in Japan.

e.	Increased risk in:

i.	previous NTD.

ii.	folate deficiency.

iii.	use of valproate during pregnancy.

iv.	females.

iv.	lower socioeconomic groups.

f.	Recurrence risk:

i.	4 – 8%: 1 previous NTD.

ii.	10%: 2 previous NTDs.

g.	NTDs are found commonly in spontaneous first trimester miscarriages.

h.	Polygenic inheritance and environment and teratogenic factors have been implicated as possible etiologies.

3.	Definitions

a.	Spinal dysraphism: encompasses abnormalities of the cranium and spine.

b.	Spina bifida occulta: incomplete closure of the neural canal in the lumbosacral region, not associated with abnormalities of the meninges, spinal cord or nerve roots.

c.	Spina bifida cystica: 

i.	protrusion of a midline sac through a spinal defect.

ii.	divided into myelomeningocele and meningocele

d.	Meningocele: NTD resulting in herniation of the meninges through a vertebral defect only and not the cord itself.

e.	Myelomeningocele: 

i.	NTD resulting in herniation of the meninges and spinal cord through the posterior bony vertebral column that has failed to form.

ii.	most common NTD compatible with life.

f.	Anencephaly:

i.	incidence: 1:1000 live births.

ii.	failure of closure of the rostral neuropore results in rudimentary brain and a large defect of the meninges and skull.

iii.	incompatible with life.

g.	Cranial meningocele: the underlying brain is normal, but a meningeal sac protrudes through a skull defect.

h.	Encephalocele: 

i.	midline defect of the skull with protrusion of brain.

ii.	associated with developmental delay, visual defects, hydrocephalus, seizures and microcephaly.

I.	Associated anomalies:

Part of CNS	Anomalies	
Skull	•	Aqueductal stenosis with hydrocephalus.
•	Arnold Chiari malformation.	
Spinal cord	•	Syringomyelia.
•	Tethered cord syndrome.	

Clinical features 

1.	Spina bifida occulta

a.	Mostly asymptomatic.

b.	Diagnosed incidentally as the result of an X-ray of the spinal column for other investigations.

c.	Ectodermal abnormalities:

i.	dermal pit.

ii.	depression with a tuft of hair.

iii.	lipoma.

iv.	skin discoloration of dermal sinus.

d.	Neural tethering may cause bladder and lower limb problems (cauda equina syndrome).

2.	Meningocele

a.	Fluid-filled midline sac that may transilluminate.

b.	Usually covered by skin or a membrane.

c.	Complications depend on the level and severity of the lesion.

3.	Myelomeningocele

a.	Cystic midline structure covered by thin layer of partially epithelized tissue with remnants of neural tissue visible beneath the membrane.

b.	Distribution:

i.	75% lumbosacral.

ii.	25% thoracic.

c.	Complications are dependent on the level of the lesion.

Complications of Myelomeningocele

1.	Orthopaedic complications

a.	Lower motor signs:

i.	flaccid paralysis of the lower limbs.

ii.	absence of deep tendon reflexes (dependent on level).

iii.	sensory loss in lower limbs (following dermatomal distribution).

b.	Scoliosis:

i.	impairment of balance.

ii.	decreased lung capacity leading to restrictive lung disease.

iii.	increased risk of infection.

iv.	cor pulmonate.

v.	impairment of height.

vi.	need for surgery.

c.	Kyphosis: 

i.	increased risk of need for multiple shunt revisions.

ii.	problems with sitting.

d.	Postural abnormalities:

i.	talipes equinovarus.

ii.	dislocation or subluxation of the hips.

e.	Gait disturbances.

2.	Neurogenic bladder

a.	Detrusor-sphincter dyssynergia.

b.	Urinary incontinence.

c.	Retention of urine.

d.	Urinary tract infections.

e.	Vesicoureteric reflux.

f.	Hydronephrosis and hydroureter.

g.	Renal impairment and renal failure.

3.	CNS complications

a.	Associated with Arnold-Chiari malformation (ACM) and hydrocephalus.

b.	Seizures.

c.	Meningitis.

d.	Usually intectually normal unless complications arise from hydrocephalus or meningitis.

4.	Other complications

a.	Constipation.

b.	Trophic ulcers of the skin.

c.	Sexual dysfunction.

d.	Psychosocial problems. 

History

1.	Presenting complaint

a.	Complications of spina bifida.

b.	Follow-up treatment / surgery.

c.	Unrelated medical problems.

2.	Specific medical problems

a.	Hydrocephalus: presence and problems with shunt.

b.	Urinary system:

i.	infections.

ii.	operations.

iii.	routine tests: reflux, kidney damage.

iv.	medications: antibiotics, anticholinergics.

c.	Orthopaedic problems:

i.	feet and hips: deformity, pressure areas, problems with splints, calipers, crutches or wheelchairs.

ii.	back: kyphoscoliosis.

d.	Other medical complications:

i.	eyes: squint, amblyopia.

ii.	skin care: pressure ulcers, burns, latex allergy.

iii.	growth and development: precocious puberty, short stature, obesity.

e.	Coordination problems.

3.	Functional ability

a.	Mobility:

i.	degree of ambulation.

ii.	aids used.

iii.	therapy: sessions with physiotherapists.

b.	Incontinence care:

i.	program for urinary incontinence: CIC, pads, penile appliances.

ii.	program for bowel care: regular toileting, laxatives, suppositories, enemas.

c.	Education:

i.	type of schooling: normal / special school.

ii.	problems with learning.

d.	Development problems:

i.	self-esteem.

ii.	adolescent problems of identity.

iii.	degree of independence.

4.	Past history

a.	Pregnancy and birth history.

b.	Antenatal screening.

c.	Family history of NTDs.

d.	Diagnosis.

e.	Initial management, understanding of the condition and expectations.

f.	Management: 

i.	complications.

ii.	infections.

iii.	hospitalizations.

iv.	operations.

5.	Social history

a.	Impact on child:

i.	restricted opportunities.

ii.	fewer friends; teasing.

iii.	poor motivation.

iv.	depression.

b.	Schooling and social integration.

c.	Family.

d.	Community and financial supports.

Clinical Examination

1.	General Plan

a.	Demonstrate level of lesion.

b.	Do a functional assessment.

c.	Look for associated abnormalities / complications.

2.	General Inspection

a.	Introduction:

i.	the child should be undressed down to the nappies or underpants.

ii.	interact with child to assess degree of development.

b.	Assess of signs of severe ACM:

i.	stridor.

ii.	apnoea.

iii.	a hoarse voice.

iv.	NG tube.

v.	eyes: nystagmus / squint.

c.	Vital signs:

i.	febrile: possible shunt infection.

ii.	tachypnoea: aspiration pneumonia.

iii.	hypertension: CRF.

iv.	tachycardia: cardiac failure secondary to CRF. 

d.	Skin:

i.	pressure sores.

ii.	scars: VP shunts, tendon releases. 

e.	Posture:

i.	describe posture in detail, focusing on each joint systematically.

ii.	note any deformities: talipes equinovarus, dislocated hips.

f.	Muscle bulk: upper vs lower limbs.

g.	Movements:

i.	upper vs lower limbs.

ii.	spontaneous / paucity of movements.

iii.	unsteadiness / ataxia: ACM.

h.	Assess status of shunt:

i.	trace shunt.

ii.	request for X-ray to assess shunt position.

I.	Growth parameters:

i.	head circumference: increased.

ii.	height: usually decreased.

iii.	arm span.

iv.	weight.

3.	Demonstrate site of lesion

a.	Examination of back:

i.	note site of lesion.

ii.	size of repair scar.

iii.	kyphoscoliosis.

iv.	scars: fixation rods for kyhoscoliosis. 

b.	Demonstrate the sensory level with a pin.

c.	Palpation: muscle bulk.

d.	Check tone, power, reflexes (including with reinforcement).

e.	Joint movement:

i.	hip: fixed flexion deformity; check for dislocation last.

ii.	knee: fixed hyperextension.

iii.	ankle: fixed dorsiflexion.

f.	Check hips for dislocation.

g.	Estimation of level of lesion:

Level of lesion	Clinical features	
Above L1	•	Total paraplegia.
•	Absent hip flexion. 
•	‘Frog-leg’ position.	
High lumbar zone	•	Child lie in position of flexion and adduction at the hips.	
Preserved L3	•	Allow an infant to exhibit some kicking movements, with some knee flexion and extension.	
Low lumbar zone	•	Position of hip flexion & adduction.
•	Good knee flexion & extension, and ankle dorsiflexion.	
S3 and below	•	Spare lower limb sensory & motor function.
•	Paralysis of bladder and anal sphincters.
•	Saddle anaesthesia.	

4.	Abdomen

a.	Inspection:

i.	scars: VP shunt.

ii.	ileal conduit: CRF. 

iii.	patulous anus.

iv.	dribbling of urine.

v.	Tanner staging (precocity).

vi.	pressure sores.

b.	Palpate kidneys for hydronephrosis.

c.	Percuss bladder for urinary retention.

d.	Urinalysis:

i.	CRF.

ii.	shunt nephritis.

iii.	UTI.

5.	Eyes

a.	Inspect: 

i.	nystagmus.

ii.	squint.

b.	Visual acuity.

c.	External ocular movements:

i.	sixth nerve palsy: raised ICP.

ii.	impaired upward gaze: Parinaud syndrome with hydrocephalus.

d.	Fundi:

i.	papilloedema: raised ICP.

ii.	optic atrophy: long-standing raised ICP.

6.	Hearing and bulbar function

a.	Assess hearing.

b.	Check lower cranial nerves.

c.	Suck and swallow.

d.	Gag reflex (if cannot swallow).

e.	Tongue atrophy.

7.	Upper limbs: full examination for signs of syringomyelia.

8.	Chest examination for signs of cardiac failure due to:

i.	hypertension: CRF.

ii.	cor pulmonale: kyphoscoliosis.

9.	Functional and development assessment

10.	Presentation

a.	This is a X year-old boy who is intellectually normal.....(mental function) with spina bifida at....(level of lesion).

b.	He is able to......(functional ability).

c.	His condition is / not complicated by.....(presence and absence of important complications).

Investigations

1.	At Birth

a.	Vertebral X-ray.

b.	CT / MRI spine.

c.	CT / MRI brain or cranial ultrasound to exclude hydrocephalus.

d.	Sacral ultrasound for spina occulta in young babies. 

2.	Renal

a.	Periodic renal ultrasounds, renal function tests, urine microscopy and culture.

b.	Micturating cystourethrogram to exclude vesicoureteric reflux.

c.	DMSA: to look for renal scarring.

d.	Urodynamics: to assess detrusor-sphincter dyssynergia.

3.	Orthopaedic: appropriate X-rays.

4.	Chest X-rays

a.	Check shunt position.

b.	Cardiac status.

c.	Aspiration pneumonia.

5.	Neuroimaging to exclude hydrocephalus.

6.	IQ assessment

Management

1.	Goals

a.	To promote good health in the short and long term.

b.	To promote maximum function in the child so that normal developmental sequences and timing can be followed to enable maximum independence for the child and family.

c.	To promote good family functioning.

2.	Management involves a team approach:

a.	Physiotherapy: ambulation training, wheelchair mobility.

b.	Occupational therapy: functional training, activities of daily living.

c.	Positioning orthoses: ankle-knee orthoses, hip positioning brace.

d.	Orthopaedic surgical procedures: tendon releases or transfers, surgery for dislocated hips.

e.	Mobility aids: crutches, wheelchairs.

f.	Education.

3.	Management at birth 

a.	Approach:

i.	assess severity of lesion.

ii.	surgical repair of lesion.

iii.	assess presence of hydrocephalus.

b.	Supportive care in inoperable lesions:

i.	recognize early those lesions which are inoperable because of massive bony deformity and extensive skin loss which would prevent closure of the defect.

ii.	children with high lesions (thoracic and thoracolumbar), significant hydrocephalus at birth, or major kyphosis have a increased mortality in early life and substantial morbidity if they survive.

iii.	in these circumstances, in discussion with the family, supportive care may be recommended.

c.	Presence of hydrocephalus

i.	careful serial evaluation of head circumference and ventricular size by ultrasound or CT scan will indicate if hydrocephalus is developing.

ii.	once it is established that progressive hydrocephalus is present, a shunt procedure is recommended.

d.	It is critical to begin to establish an empathetic therapeutic relationship with the parents in the newborn period, which forms the foundation for ongoing support throughout childhood.

4.	Hydrocephalus and VP shunts

a.	Pathology:

i.	this is seen in 90% of all children with spina bifida.

ii.	the caudal hindbrain of the Arnold-Chiari II malformation is present in almost all patients.

b.	Associated problems:

i.	an increased chance of intellectual impairment.

ii.	shunt complications such as infection and obstruction.

iii.	seizures.

c.	Use of VP shunts:

i.	an average of two shunt changes are needed in the first 10 years.

ii.	management includes appropriate schooling for intellectual impairment, and education regarding complications of shunts and their presentation. 

d.	Site of insertion:

i.	right side of anterior part of lateral ventricle (non-dominant hemisphere).

ii.	avoids speech areas in left hemisphere.

e.	Underdrainage:

i.	due to blockage of shunt tubing, the shunt breaking or parts becoming disconnected.

ii.	presentation: headache (worse on waking, before rising in the morning), vomiting, dizziness, insidious deterioration in behavior or intellectual functioning, worsening of fitting.

f.	Overdrainage:

i.	similar presentation to underdrainage.

ii.	if rapid, a subdural hemorrhage can result.

g.	Shunt infection:

i.	due to bacteria getting into CSF or shunt at time of operation, hence commonest within first 3 days of shunt placement.

ii.	infection can present as shunt blockage within weeks or months of operation.

iii.	an infected shunt must be removed and replaced with a new clean shunt.

h.	Investigations with shunt problems:

i.	CSF.

ii.	plain X-rays to demonstrate shunt position and to check for disconnection.

iii.	cranial CT or MRI scan.

5.	Surgery

a.	Arnold Chiari malformation:

i.	may be severe with laryngeal stridor and apnoeic spells.

ii.	life threatening episodes may necessitate neurosurgical intervention to decompress the posterior fossa.

b.	Management of physical disability and mobility:

i.	physiotherapists play an essential role in reducing deformities and encouraging mobility.

ii.	foot derformities are common at birth due to unopposed muscular activity in utero.

iii.	splinting and passive stretching are the mainstays of treatment in early life.

iv.	surgery may be needed for dislocated hips.

c.	Spinal deformities:

i.	a significant percentage of children will develop scoliosis and many of these will require spinal instrumentation.

ii.	surgical correction techniques include excision of apical vertebrae, stabilized with instrumentation, and multiple lordosing intervertebral osteotomies.

d.	Tethered spinal cord:

i.	following repair of a myelomeningocele, the lower end of the spinal cord may become tethered to the site of repair.

ii.	as the child grows, this may cause progressive neurological deterioration in motor or sensory function, or in bladder control.

iii.	MRI scans are performed to demonstrate the tethering process.

iv.	if the neurological deterioration is significant, consideration should be given to neurosurgical release of the tethered cord. 

e.	Neuropathic fractures:

i.	fractures of the lower limbs are common in children with myelomeningocele due to disuse osteoporosis.

ii.	fractures may occur with minimal trauma.

iii.	encouraging children to walk, or stand in a standing frame may improve the mineralization of long bones and lessen the likelihood of spontaneous fractures. 

6.	Neuropathic bladder

a.	Almost all children with myelomeningocele have a neuropathic bladder.

b.	Failure to empty the bladder may lead to:

i.	recurrent UTIs.

ii.	vesicoureteric reflux.

iii.	renal calculi.

iv.	hydronephrosis.

v.	hypertension.

vi.	renal failure in 5 – 10% of patients. 

c.	Management is by clean intermittent catheterization (CIC) performed 4 – 5 times daily by the parents, and later by the child.

d.	Prophylactic antibiotics may be required for recurrent UTIs.

e.	Bladder augmentation and / or artificial sphincter operations (Mitrafanoff procedure) may be indicated.

7.	Neuropathic bowel

a.	Most children have limited or absent rectal sensation and have little or no bowel control.

b.	Constipation with megacolon, faecal impaction and overflow incontinence is the major risk in spina bifida.

c.	Bowel management:

i.	avoidance of constipation.

ii.	regular and predictable timing of rectal emptying.

iii.	dietary regulation for stool consistency.

c.	Rectal emptying by suppositories or enemas may be necessary.

d.	Refractory cases may require regular bowel washouts. 

8.	Skin

a.	Pressure ulcers or burns in anaesthetic areas are common.

b.	Parents are encouraged to check anaesthetic areas daily for the presence of pressure sores.

c.	Poorly fitting calipers, crutches or wheelchairs can cause substantial skin breakdown before they are noted.

d.	Early recognition and treatment is essential to prevent long periods of morbidity and hospitalization. 

9.	Education

a.	Children with myelomeningocele often have specific learning problems, requiring assistance at school.

b.	Many children have a poor attention span with distractibility.

c.	Problems with fine motor control and visual perceptual difficulties are present frequently.

10.	Social problems

a.	Personal: low self-esteem, ongoing dependence on parents.

b.	Adolescence stress.

c.	Sex education: impotence in males. 

11.	Prevention

a.	Women of child-bearing years should be encouraged to eat food rich in folate, e.g. whole grain, spinach, broccoli, beans.

b.	Women who plan to get pregnant should take a supplement 0.4 mg folate daily and 1 mg folate daily if pregnant.

c.	Decrease recurrence rate in patients at risk with 4 mg of folate daily from the time of conception through the first trimester.

12.	Antenatal screening

a.	The presence of abnormally high levels of alpha-fetoprotein in the amniotic fluid has a high correlation with myelomeningocele.

b.	Alphaprotein is a component of fetal CSF and it leaks into the amniotic fluid from the open neural tube defect.

c.	The detection rate for open neural tube defects using maternal serum screening is approximately 80%.

d.	Ultrasound can detect or confirm the extent of the neural tube defect.

13.	Genetic counseling

a.	Risk determination: determine subsequent risk of child getting spina bifida.

b.	Risk options: prevention and antenatal screening.

c.	Support services: direct parents to appropriate support resources for spina bifida patients.