Spina Bifida (Myelomeningocele)

1. Clinical Overview

Summary

Spina bifida represents a spectrum of neural tube defects (NTDs) arising from incomplete closure of the embryonic neural tube during the fourth week of gestation (days 21-28). The term encompasses a range from asymptomatic spina bifida occulta (incomplete vertebral arch fusion with intact neural elements) to the severe and debilitating myelomeningocele (open spina bifida), in which herniated neural tissue through a vertebral defect results in profound neurological disability. [1,2]

Myelomeningocele is the most common permanently disabling birth defect affecting the central nervous system in developed nations. The condition presents with a characteristic triad of motor and sensory deficits below the lesion level, neurogenic bladder and bowel dysfunction, and associated Arnold-Chiari type II malformation with resultant hydrocephalus in 80-90% of cases. [3,4]

The global incidence has declined dramatically following implementation of periconceptional folic acid supplementation programs and prenatal screening initiatives. Current prevalence in countries with mandatory fortification ranges from 0.3 to 0.8 per 1000 live births, representing a 50-70% reduction from historical rates. [5,6] Despite improved prevention, affected individuals require lifelong multidisciplinary care with multiple surgical interventions throughout childhood and adolescence.

Clinical Pearls

Latex Allergy - Critical Safety Issue: Between 50-73% of children with spina bifida develop clinically significant latex hypersensitivity, compared to 1% in the general paediatric population. This elevated risk results from repeated exposure to latex proteins during multiple surgeries and daily clean intermittent catheterisation (CIC). Type I hypersensitivity reactions range from contact urticaria to life-threatening anaphylaxis. [7] All spina bifida patients must be treated in latex-free environments using non-latex gloves, catheters, and anaesthetic equipment. Alternative allergens include banana, avocado, kiwi, and chestnuts (cross-reactive proteins).

The VP Shunt - Most Common Complication: Hydrocephalus requiring ventriculoperitoneal (VP) shunt placement affects 80-90% of children with myelomeningocele due to associated Chiari II malformation causing posterior fossa crowding and aqueductal stenosis. Shunt malfunction presents with headache, vomiting, lethargy, bulging fontanelle (infants), or subtle behavioural changes. [8] Emergency imaging (CT head or shunt series) is mandatory in any spina bifida patient presenting with these symptoms. Shunt infection rates approach 5-15% per shunt insertion, typically occurring within the first 6 months post-operatively.

Occulta Cutaneous Markers: Spina bifida occulta may manifest with overlying skin stigmata including hypertrichosis (hairy patch), deep sacral dimple (> 2.5cm above anal verge or > 5mm diameter), dermal sinus tract, subcutaneous lipoma, or capillary haemangioma. These markers warrant spinal ultrasound (infants less than 6 months) or MRI to exclude occult spinal dysraphism with potential for tethered cord syndrome. [9]

Level Determines Function: The anatomical level of the myelomeningocele directly predicts ambulatory potential and bladder function. Thoracic lesions result in complete paraplegia with minimal ambulation potential. L3-L4 lesions allow household ambulation with extensive bracing. Sacral lesions may permit community ambulation with minimal assistance. [10]

The Two-Hit Hypothesis of Paralysis: Neurological deficit in myelomeningocele results from both primary neurulation failure (in utero developmental arrest) and secondary damage from amniotic fluid exposure to the exposed neural placode throughout gestation. This "two-hit" mechanism provides the rationale for prenatal surgical repair to limit secondary injury. [11]

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2. Epidemiology

Global Prevalence

Neural tube defects represent one of the most common congenital anomalies worldwide, with significant geographic and ethnic variation in prevalence rates. Prior to folic acid fortification programs, the global incidence ranged from 1-2 per 1000 births in most populations, with certain high-risk regions (Ireland, Wales, Northern India, Northern China) experiencing rates of 3-6 per 1000 births. [12,13]

Current Prevalence (Post-Fortification):

• United States: 0.7 per 1000 live births
• United Kingdom: 0.5 per 1000 live births
• Australia: 0.4 per 1000 live births
• Countries without fortification: 1.0-2.5 per 1000 live births

Approximately 300,000 new cases of neural tube defects occur globally each year, with the majority (> 95%) occurring in low- and middle-income countries lacking fortification programs. [14]

Risk Factors

Modifiable Risk Factors:

1. Folate Deficiency (PRIMARY RISK FACTOR)

   • Inadequate periconceptional folic acid intake increases risk 3-5 fold
   • Mechanism: Folate serves as essential cofactor for DNA synthesis and methylation during rapid cell division of neurulation
   • Preventable with 400 μg daily supplementation commenced preconceptionally [15,16]

2. Maternal Obesity

   • BMI > 30 kg/m² increases risk 2-fold
   • BMI > 35 kg/m² increases risk 3-4 fold
   • Mechanisms include relative folate deficiency, hyperinsulinaemia, and altered embryonic gene expression [17]

3. Maternal Diabetes (Pre-existing)

   • Type 1 or Type 2 diabetes increases risk 2-3 fold
   • Risk correlates with periconceptional glycaemic control (HbA1c)
   • Hyperglycaemia induces oxidative stress and apoptosis in neuroepithelium [18]

4. Antiepileptic Drug Exposure

   • Sodium Valproate: 10-20 fold increased risk (1-2% absolute risk)
   • Carbamazepine: 2-3 fold increased risk
   • Lamotrigine: Minimal to no increased risk
   • Valproate inhibits folate metabolism and histone deacetylases [19]

5. Hyperthermia

   • Maternal fever > 38.9°C in first trimester
   • Sauna or hot tub use
   • Mechanism: Heat shock protein disruption during neurulation [20]

Non-Modifiable Risk Factors:

1. Previous NTD-affected Pregnancy

   • Recurrence risk: 2-5% (20-50 fold increase over baseline)
   • Two previous affected pregnancies: 10% recurrence risk
   • Justifies high-dose folic acid (5mg daily) in subsequent pregnancies [21]

2. Ethnicity

   • Hispanic populations: Highest risk (particularly Mexican ancestry)
   • Celtic populations: Elevated risk
   • African and Asian populations: Lower risk

3. Genetic Factors

   • Polygenic inheritance pattern
   • Mutations in folate metabolism genes (MTHFR C677T variant)
   • Variants in planar cell polarity pathway genes

Prevention Strategies

Primary Prevention - Folic Acid Supplementation:

Population-Level Interventions:

1. Mandatory Fortification Programs

   • USA (1998): Fortification of cereal grain products with 140 μg folic acid per 100g flour
   • Result: 25-50% reduction in NTD prevalence
   • UK implemented fortification in 2021 (140 μg per 100g flour)
   • Over 80 countries now have mandatory fortification programs [23]

2. Prenatal Screening and Diagnosis

   • Maternal serum alpha-fetoprotein (MSAFP) screening at 15-20 weeks
   • Detailed fetal ultrasound (anomaly scan) at 18-22 weeks
   • Termination of pregnancy offered in severe cases (ethically complex)

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3. Pathophysiology

Embryology of Neural Tube Formation

Neural tube formation (neurulation) occurs during gestational days 18-28 (Carnegie stages 8-12) through a complex, highly orchestrated process of embryonic folding and fusion. Understanding normal neurulation is essential to comprehending the pathogenesis of spina bifida. [24,25]

Primary Neurulation (Days 18-26):

1. Neural Plate Formation (Day 18)

   • Dorsal ectoderm thickens in response to notochord signalling
   • Bone morphogenetic protein (BMP) inhibition by noggin and chordin
   • Medial neural plate cells express Sonic hedgehog (Shh), Pax3, Pax7

2. Neural Plate Folding (Days 19-20)

   • Median hinge point (MHP) forms at midline
   • Paired dorsolateral hinge points (DLHP) form laterally
   • Neural folds elevate, creating neural groove

3. Neural Fold Fusion (Days 22-28)

   • Initial closure at cervical level (Closure Site 1) on day 22
   • Bidirectional "zipper-like" progression
   • Cranial closure completes at anterior neuropore (Closure Site 2) on day 24
   • Caudal closure completes at posterior neuropore (Closure Site 3) on day 26-28
   • Failure of caudal closure → Spina bifida
   • Failure of cranial closure → Anencephaly (uniformly fatal)

4. Neural Crest Cell Migration

   • Epithelial-to-mesenchymal transition at fusion points
   • Migration of neural crest cells from dorsal neural tube
   • Differentiation into peripheral nervous system, melanocytes, craniofacial structures

Secondary Neurulation (Days 26-48):

• Formation of caudal neural tube (sacral and coccygeal segments)
• Mesenchymal condensation and canalization
• Defects in secondary neurulation → Spina bifida occulta, lipomyelomeningocele

Molecular Mechanisms of Neural Tube Closure

Neural tube defects result from disruption of multiple molecular pathways:

1. Planar Cell Polarity (PCP) Pathway

   • Governs coordinated cell movements during convergent extension
   • Key genes: VANGL1, VANGL2, CELSR1, SCRIB, DVL
   • Mouse knockouts of PCP genes produce craniorachischisis (complete failure of neurulation)

2. Folate-Mediated One-Carbon Metabolism

   • Folate required for thymidine and purine synthesis (DNA replication)
   • S-adenosylmethionine (SAM) production for DNA/histone methylation
   • Disruption impairs rapidly dividing neuroepithelial cells
   • MTHFR C677T polymorphism reduces enzyme activity 50-70%

3. Apoptosis Dysregulation

   • Excessive apoptosis at neural fold fusion points
   • Hyperglycaemia-induced oxidative stress triggers apoptosis
   • P53-mediated apoptotic pathway activation

Classification of Spina Bifida

1. Spina Bifida Occulta (Closed Neural Tube Defect)

• Definition: Defect in posterior vertebral arch (lamina and spinous process) without herniation of meninges or neural tissue
• Prevalence: 10-20% of general population (often incidental finding)
• Location: Most commonly L5-S1
• Clinical Significance: Usually asymptomatic; 10-15% may have underlying spinal cord abnormality (tethered cord, diastematomyelia, lipoma)
• Cutaneous Stigmata: Hypertrichosis, sacral dimple, dermal sinus, lipoma, capillary malformation

2. Meningocele (Closed Neural Tube Defect)

• Definition: Herniation of meninges and CSF through posterior vertebral defect forming a CSF-filled sac
• Spinal Cord Position: Remains within spinal canal (not herniated)
• Prevalence: 5-10% of all spina bifida cases
• Neurological Function: Usually preserved (normal motor/sensory function)
• Clinical Examination: Fluctuant, transilluminable midline sac covered by skin
• Hydrocephalus: Rare (less than 10% of cases)
• Prognosis: Excellent after surgical repair

3. Myelomeningocele (Open Neural Tube Defect) - MOST SEVERE

• Definition: Herniation of meninges, CSF, and spinal cord/nerve roots through posterior vertebral defect
• Neural Placode: Exposed, non-epithelialized neural tissue visible on examination
• Prevalence: 90-95% of clinically significant spina bifida cases
• Location: Lumbosacral region most common (75%), thoracic (20%), cervical (5%)
• Neurological Deficit: Invariably present; severity correlates with anatomical level
• Hydrocephalus: Present in 80-90% (associated Chiari II malformation)
• Prognosis: Lifelong disability requiring multidisciplinary management

4. Myeloschisis (Rachischisis)

• Definition: Complete absence of posterior neural tube closure with exposed neural tissue flush with skin surface (no herniated sac)
• Prevalence: Rare; most severe form
• Appearance: Flat, raw neural placode without overlying membrane

The "Two-Hit" Hypothesis of Spinal Cord Injury

Neurological deficit in myelomeningocele arises from both:

1. Primary Injury (In Utero)

   • Initial failure of neural tube closure (genetic/environmental)
   • Abnormal development of neural placode

2. Secondary Injury (Throughout Gestation)

   • Mechanical trauma from fetal movement
   • Chemical injury from amniotic fluid exposure
   • Progressive destruction of exposed neural tissue
   • Prenatal repair aims to prevent this secondary injury [11]

Associated Arnold-Chiari Type II Malformation

Chiari II malformation is present in virtually 100% of myelomeningocele cases and represents a constellation of posterior fossa and hindbrain abnormalities: [26]

Anatomical Features:

• Cerebellar vermis herniation through foramen magnum
• Medullary kinking and caudal displacement
• Tectal beaking (elongated tectum)
• Small posterior fossa with low-lying tentorium
• Corpus callosum dysgenesis

Pathophysiology of Hydrocephalus:

• Aqueductal stenosis (primary mechanism)
• Fourth ventricular outlet obstruction
• Impaired CSF circulation in posterior fossa
• Results in non-communicating hydrocephalus in 80-90% of cases

Clinical Manifestations:

• Hydrocephalus (predominant presentation)
• Brainstem dysfunction: dysphagia, stridor, apnoea, vocal cord paralysis
• Cranial nerve palsies (VI, VII, IX, X, XI, XII)
• Central sleep apnoea

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4. Differential Diagnosis

The differential diagnosis of a posterior midline spinal lesion in a neonate includes:

Transillumination Test:

• Meningocele: Bright transillumination (CSF-filled sac)
• Myelomeningocele: Minimal/no transillumination (solid neural tissue)
• Performed in darkened room with bright penlight applied to sac

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5. Clinical Presentation

Antenatal Detection

Over 90% of myelomeningocele cases are now detected prenatally in countries with comprehensive screening programs. [27]

Maternal Serum Screening (15-20 weeks):

• Elevated maternal serum alpha-fetoprotein (MSAFP): Sensitivity 80-85%
• AFP leaks from exposed neural tissue into amniotic fluid
• Threshold typically > 2.5 MoM (multiples of median)
• False positives: multiple gestation, abdominal wall defects, fetal demise

Ultrasound Findings (18-22 weeks anomaly scan):

1. Direct Visualization

   • Splaying of posterior vertebral elements (> 2mm separation)
   • Paravertebral cystic/solid mass
   • Absence of overlying skin
   • Lesion level identification

2. Cranial Signs (HIGHLY SPECIFIC)

   • "Lemon sign": Frontal bone scalloping (frontal bone concavity)
     • Sensitivity: 70-80% in second trimester
     • Mechanism: Reduced intracranial pressure from CSF leak
   • "Banana sign": Abnormal cerebellar configuration
     • Cerebellum wraps around brainstem
     • Obliteration of cisterna magna
     • Sensitivity: 85-95%

3. Ventriculomegaly

   • Lateral ventricular atrial diameter > 10mm
   • Present in 70-80% at initial diagnosis
   • Progressive throughout gestation

Fetal MRI (22-32 weeks):

• Confirms ultrasound diagnosis
• Assesses lesion level and Chiari II malformation severity
• Evaluates cerebral cortical development
• Guides counselling for prenatal vs postnatal repair

Neonatal Presentation

Physical Examination Findings:

1. Spinal Lesion

   • Location: Lumbosacral (75%), thoracolumbar (20%), cervical (5%)
   • Appearance:
     • Raw, weeping neural placode (open myelomeningocele)
     • Membranous covering (partially epithelialized)
     • Surrounding skin defect (typically 3-8 cm diameter)
   • Leaking CSF: Constant risk of meningitis until surgical closure

2. Neurological Assessment by Level

3. Musculoskeletal Deformities (Present at Birth)

   • Talipes equinovarus (clubfoot): 30-50% of cases; due to muscle imbalance
   • Hip dislocation: 15-30%; more common with higher lesions
   • Knee contractures: Flexion or extension contractures
   • Kyphosis: Severe gibbus deformity in thoracic lesions
   • Scoliosis: Develops in 50-90% during growth

4. Cranial Examination

   • Occipitofrontal circumference (OFC): Plot on growth chart; measure serially
   • Fontanelle: May be full/tense if hydrocephalus present
   • "Sunsetting" sign: Downward eye deviation (hydrocephalus)
   • Separated sutures: Palpable widening

5. Neurogenic Bladder Signs (May Not Be Apparent at Birth)

   • Continuous dribbling of urine
   • Palpably distended bladder
   • Absent bladder sensation
   • Absent anal wink reflex (S2-S4)
   • Patulous anus

6. Genitourinary Exam

   • Hydronephrosis (from high-pressure bladder)
   • Cryptorchidism

Presentation in Infancy and Childhood

1. Hydrocephalus (First Weeks to Months)

• Timing: 85% of shunt placements occur in first 6 months of life
• Clinical Features:
  • Progressive head enlargement (OFC crossing centiles upward)
  • Tense, bulging fontanelle
  • Suture diastasis
  • Dilated scalp veins
  • "Cracked pot" sound on skull percussion
  • Developmental delay
  • "Advanced hydrocephalus: Sunsetting eyes, lethargy, vomiting, apnoea"

2. Brainstem Dysfunction (Symptomatic Chiari II) - SURGICAL EMERGENCY

Occurs in 10-15% of infants; presents in first 3-6 months: [28]

• Swallowing difficulties: Aspiration, choking, weak cry
• Vocal cord paralysis: Stridor (inspiratory or biphasic)
• Apnoea/Bradycardia: Central sleep apnoea
• Cranial nerve palsies: Weak suck, facial weakness
• Requires: Posterior fossa decompression (suboccipital craniectomy + C1 laminectomy)

3. Tethered Cord Syndrome (Childhood/Adolescence)

Progressive neurological deterioration due to spinal cord tethering at repair site: [29]

• Incidence: 15-30% of repaired myelomeningoceles
• Timing: Usually during growth spurts (ages 5-10 years or adolescence)
• Clinical Features:
  • "Worsening motor function: Decreased ambulation, new weakness"
  • "Urological deterioration: Increased incontinence, UTIs, hydronephrosis"
  • "Pain: Lower back, leg, or radicular pain"
  • "Orthopedic worsening: Progressive scoliosis, foot deformities"
  • "Cutaneous changes: Lipoma, hairy patch at repair site"
• Diagnosis: MRI spine showing low-lying conus (below L2-L3) with thick, taut filum terminale
• Treatment: Surgical detethering (neurosurgery)

4. Shunt Malfunction (Any Age)

VP shunt complications affect > 50% of shunted patients: [30]

• Obstruction (most common): Headache, vomiting, lethargy, irritability, decreased school performance
• Infection: Fever, meningismus, wound erythema, shunt tract tenderness
  • "Timing: 70% occur within 6 months of shunt placement"
  • "Organisms: Staphylococcus epidermidis, S. aureus, Propionibacterium acnes"
• Over-drainage: Postural headaches, subdural haematomas
• Underdrainage: Symptoms of raised ICP

5. Neurogenic Bladder Complications (Ongoing)

• Urinary tract infections (UTIs): Recurrent UTIs in 40-50%
• Vesicoureteral reflux: 15-40% develop reflux
• Hydronephrosis: 10-25%; risk of chronic kidney disease
• Incontinence: Social impact, quality of life
• Bladder stones: From CIC and incomplete emptying

6. Neurogenic Bowel

• Constipation: Absent colonic motility; requires bowel management program
• Faecal incontinence: Absent sphincter tone
• Impact: Significant psychosocial burden; affects school attendance

7. Orthopaedic Complications

• Scoliosis: 50-90% develop progressive curves; may require spinal fusion
• Hip subluxation/dislocation: 15-50% depending on lesion level
• Pathological fractures: Due to osteopenia, insensate lower limbs
• Pressure sores: Insensate skin, wheelchair dependence

8. Neurodevelopmental and Cognitive

• Intellectual Disability: 25-30% have IQ less than 70 (often related to hydrocephalus severity, recurrent shunt infections)
• Learning Disabilities: 50-70% require educational support
  • Executive dysfunction (planning, organization)
  • Visuospatial deficits
  • Attention deficits
• "Cocktail Party Syndrome": Fluent expressive language with poor comprehension

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6. Investigations

Antenatal Investigations

1. Maternal Serum Alpha-Fetoprotein (MSAFP) - 15-20 weeks

• Elevated in 80-85% of open NTDs
• Threshold: > 2.5 MoM
• Requires confirmation with ultrasound

2. Detailed Fetal Ultrasound - 18-22 weeks

• Splaying of posterior vertebral ossification centers
• Lemon sign (frontal bossing)
• Banana sign (cerebellar abnormality)
• Ventriculomegaly
• Lesion level determination

3. Fetal MRI - 22-32 weeks

• Superior soft tissue resolution
• Confirms Chiari II malformation
• Assesses lesion level, cortical development
• Guides prenatal counselling

4. Amniocentesis (if diagnosis unclear)

• Amniotic fluid AFP and acetylcholinesterase
• Not routinely performed given ultrasound accuracy

Postnatal Investigations - Immediate (Day 1)

1. Complete Physical Examination

• Detailed neurological examination (motor/sensory level determination)
• Occipitofrontal circumference (OFC) measurement
• Assess lesion (size, location, epithelialization, CSF leak)

2. Cranial Imaging

• Cranial Ultrasound (via anterior fontanelle): Initial assessment of ventricular size
• MRI Brain: Definitive assessment of hydrocephalus and Chiari II malformation
  • Ventricular size
  • Chiari II features (cerebellar herniation, tectal beaking)
  • Corpus callosum assessment

3. Spinal Imaging

• MRI Spine (full spine):
  • Lesion level confirmation
  • Conus position (assess for tethering)
  • Associated anomalies (syrinx, diastematomyelia, lipoma)
  • Vertebral anomalies (hemivertebrae, butterfly vertebrae)

4. Renal/Bladder Ultrasound

• Baseline renal anatomy
• Assess for hydronephrosis (indicates high bladder pressures)
• Bladder wall thickening (trabeculation)
• Post-void residual bladder volume

5. Baseline Laboratory Tests

• Serum creatinine (renal function)
• Urinalysis and urine culture (baseline; risk of UTI with CIC)
• Full blood count (pre-operative)
• Coagulation screen (pre-operative)

Ongoing Investigations - Lifelong Surveillance

1. Urological Monitoring (Every 3-6 months in infancy; annually thereafter)

• Renal Ultrasound: Detect hydronephrosis, renal scarring, bladder changes
• Urodynamic Studies (from age 1 year):
  • Bladder capacity, compliance, detrusor pressure
  • Post-void residual volume
  • Identifies high-risk bladder (> 40 cm H₂O pressure)
  • Guides need for anticholinergic therapy
• VCUG (Voiding Cystourethrogram): If recurrent UTIs or hydronephrosis
  • Assess for vesicoureteral reflux
• Serum Creatinine/eGFR: Monitor renal function
• DMSA Scan: If renal scarring suspected

2. Neurosurgical Monitoring

• Serial OFC Measurements: Weekly in first 3 months; monthly to 1 year; at each clinic visit
• Cranial Imaging:
  • "If shunt present: Immediate CT if malfunction suspected"
  • "MRI brain: Annually (or if new symptoms)"
• Spinal MRI:
  • At ages 1, 5, 10, 15 years (or if clinical concern for tethering)
  • Assess conus position, syrinx formation

3. Orthopaedic Monitoring

• Spine X-rays (AP and lateral):
  • At diagnosis of scoliosis
  • Every 6-12 months if scoliosis present
  • Cobb angle measurement (> 40° may require surgery)
• Hip X-rays:
  • Every 6-12 months in infancy/childhood
  • Assess for subluxation/dislocation (Shenton's line, acetabular index)

4. Developmental Assessment

• Formal developmental/cognitive assessment at 1, 3, 5 years and school entry
• Educational psychology input as needed

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7. Management

The management of spina bifida requires lifelong, coordinated multidisciplinary care involving neurosurgery, urology, orthopaedics, paediatrics, physiotherapy, occupational therapy, psychology, and specialist nursing.

Management Algorithm - Neonate with Myelomeningocele

┌─────────────────────────────────────────────┐
│  DELIVERY ROOM (or antenatal diagnosis)    │
│  • Avoid trauma to lesion                  │
│  • Position: Prone or lateral              │
│  • Cover lesion: Sterile saline-soaked     │
│    non-adherent gauze + plastic wrap       │
│  • LATEX-FREE environment                  │
│  • Nothing per rectum (avoid meningitis)   │
└──────────────────┬──────────────────────────┘
                   ↓
┌─────────────────────────────────────────────┐
│  NEONATAL INTENSIVE CARE UNIT              │
│  • Keep prone/lateral                      │
│  • Broad-spectrum IV antibiotics           │
│    (e.g., Ampicillin + Gentamicin)         │
│  • Maintain sterile dressing               │
│  • Baseline investigations (see above)     │
│  • MDT discussion + family counselling     │
└──────────────────┬──────────────────────────┘
                   ↓
┌─────────────────────────────────────────────┐
│  SURGICAL CLOSURE (within 24-72 hours)     │
│  GOALS:                                    │
│  • Prevent meningitis/ventriculitis        │
│  • Protect neural tissue                   │
│  • Create watertight dural closure         │
│  • Achieve skin coverage                   │
│  TECHNIQUE:                                │
│  • Resect neural placode margins           │
│  • Reconstruct dura (watertight)           │
│  • Myofascial flap closure                 │
│  • Skin closure (primary or rotational)    │
│  NOTE: Does NOT reverse existing deficit   │
└──────────────────┬──────────────────────────┘
                   ↓
┌─────────────────────────────────────────────┐
│  HYDROCEPHALUS MANAGEMENT                  │
│  Monitor: OFC, fontanelle, US/MRI          │
│                                            │
│  IF HYDROCEPHALUS DEVELOPS (80-90%):       │
│  • VP Shunt insertion                      │
│    (typically 7-14 days post-closure)      │
│  • Programmable shunt preferred            │
│  • Endoscopic Third Ventriculostomy (ETV)  │
│    ± Choroid Plexus Cauterization (CPC)    │
│    (alternative in select cases)           │
└──────────────────┬──────────────────────────┘
                   ↓
┌─────────────────────────────────────────────┐
│  LONG-TERM MULTIDISCIPLINARY MANAGEMENT    │
│  • Urology (CIC, anticholinergics)         │
│  • Orthopaedics (bracing, surgery)         │
│  • Physiotherapy (mobility, equipment)     │
│  • Bowel management program                │
│  • Developmental/educational support       │
│  • Family/psychosocial support             │
└─────────────────────────────────────────────┘

1. Prenatal Management - Fetal Surgery (The MOMS Trial)

Background: The landmark Management of Myelomeningocele Study (MOMS), published in the New England Journal of Medicine in 2011, was a multicentre randomized controlled trial comparing prenatal vs postnatal repair of myelomeningocele. [31]

MOMS Trial Design:

• Participants: 183 pregnant women (19-25 weeks gestation) with singleton fetuses with myelomeningocele (lesion level T1-S1)
• Intervention: Prenatal open hysterotomy repair vs standard postnatal repair
• Primary outcomes: Death or need for VP shunt at 12 months; Mental Development Index (MDI) and motor function at 30 months

MOMS Trial Results:

Maternal/Fetal Risks of Prenatal Repair:

• Preterm birth: Mean gestational age 34 weeks vs 37 weeks
• Premature rupture of membranes: 46% vs 8%
• Oligohydramnios: 21% vs 4%
• Uterine dehiscence risk: 10% (requires cesarean delivery in all subsequent pregnancies)
• Maternal pulmonary edema: 6%

Current Evidence (Post-MOMS):

Following MOMS, fetoscopic (percutaneous) repair techniques have emerged as less invasive alternatives to open hysterotomy. Recent studies show: [32,33]

• Reduced maternal morbidity (no hysterotomy)
• Later gestational age at delivery (36-37 weeks)
• Similar shunt rates to open fetal repair (30-50%)
• Comparable neurodevelopmental outcomes

Indications for Prenatal Repair (2025 Consensus Criteria):

• Singleton pregnancy
• Gestational age 19+0 to 25+6 weeks
• Myelomeningocele with upper lesion boundary T1-S1
• Evidence of hindbrain herniation (Chiari II)
• Normal karyotype
• No other major anomalies
• Maternal age ≥18 years
• BMI less than 35 kg/m²
• Specialized fetal surgery centre

Contraindications:

• Multiple gestation
• Severe kyphosis (> 30°)
• Maternal medical contraindications (cardiac disease, etc.)
• Placental abnormalities (previa, abruption risk)
• Psychosocial inability to comply with follow-up

2. Postnatal Surgical Repair (Standard Care)

Timing:

• Urgent repair within 24-72 hours of birth to minimize infection risk
• Earlier closure (less than 24h) may reduce ventriculitis risk

Surgical Technique:

1. Patient Positioning: Prone
2. Excision of Neural Placode Margins: Remove abnormal epithelium at placode edges
3. Dural Reconstruction: Mobilize dura; achieve watertight primary closure with non-absorbable sutures
4. Myofascial Layer: Bilateral paraspinal muscle flaps rotated medially
5. Skin Closure:
   • Primary closure if sufficient laxity
   • Rotational flaps (e.g., bilateral V-Y advancement) if large defect
   • Split-thickness skin graft (rare, suboptimal)

Complications of Repair:

• Wound dehiscence: 5-10%
• CSF leak: 10-15%
• Infection (meningitis/ventriculitis): 5-10%
• Tethered cord: 15-30% (long-term)

3. Hydrocephalus Management

VP Shunt Insertion:

• Indications:

  • Progressive ventriculomegaly (crossing centiles on serial imaging)
  • Clinical signs of raised ICP (bulging fontanelle, OFC crossing centiles, sunsetting, apnoea)
  • Typically required in 80-90% of myelomeningocele cases

• Timing: Usually 7-14 days post-myelomeningocele closure (allow wound healing)

• Shunt Components:

  • Proximal catheter (lateral ventricle)
  • Valve (programmable valves preferred; allow non-invasive pressure adjustment)
  • Distal catheter (peritoneal cavity most common)

• Complications: [34]

  • "Obstruction (40-50% within 2 years): Proximal (choroid plexus) or distal (omental wrapping)"
  • "Infection (5-15% per insertion): S. epidermidis, S. aureus"
  • "Over-drainage: Slit ventricle syndrome, subdural collections"
  • "Shunt migration: Catheter tip displacement"

Endoscopic Third Ventriculostomy (ETV) ± Choroid Plexus Cauterization (CPC):

• Alternative to shunt in select patients
• Success rate lower in myelomeningocele-associated hydrocephalus (40-60%) vs obstructive hydrocephalus (70-80%)
• Advantage: Avoids shunt complications
• Best suited for older infants (> 6 months) with aqueductal stenosis

4. Urological Management - CRITICAL for Renal Preservation

Goals:

1. Preserve renal function (prevent reflux, hydronephrosis, chronic kidney disease)
2. Achieve urinary continence (social continence)
3. Minimize UTI risk

Clean Intermittent Catheterisation (CIC): [35,36]

• Cornerstone of neurogenic bladder management
• Technique:
  • Sterile or clean catheter inserted via urethra into bladder every 3-4 hours
  • Bladder emptied completely
  • Catheter discarded (single-use) or cleaned (reusable)
• Initiation: Begin in infancy (parents perform); transition to self-catheterisation at age 5-7 years
• Frequency: 4-6 times daily to maintain bladder volume less than 400 mL
• Catheter Size: Age-appropriate French size (e.g., 6-8 Fr infants; 10-12 Fr children)
• Compliance: Essential for preventing renal damage; adherence challenges in adolescence

Anticholinergic Medications:

• Indication: High detrusor pressure (> 40 cm H₂O), poor bladder compliance, incontinence despite CIC
• Agents:
  • "Oxybutynin (first-line): 0.2 mg/kg/dose TDS; max 5 mg TDS"
  • "Tolterodine: Alternative if oxybutynin side effects"
  • "Solifenacin, Darifenacin: Newer agents"
• Mechanism: Competitive muscarinic receptor antagonism; reduces detrusor overactivity
• Side Effects: Dry mouth, constipation, drowsiness, blurred vision
• Monitoring: Urodynamics to assess bladder pressure reduction

Surgical Options (If Conservative Management Fails):

1. Vesicostomy (Temporary, Infants)

   • Cutaneous opening into bladder dome
   • Provides low-pressure drainage
   • Later reversal once CIC established

2. Botulinum Toxin Injection (Detrusor)

   • Reduces detrusor overactivity
   • Requires repeat injections every 6-9 months

3. Bladder Augmentation (Augmentation Cystoplasty)

   • Increases bladder capacity and compliance
   • Uses bowel segment (ileum or colon) as patch
   • Allows CIC continuation with improved continence
   • Complications: Mucus production, metabolic acidosis, malignancy risk (long-term)

4. Continent Catheterizable Channels (Mitrofanoff Procedure)

   • Appendix or ileum used to create abdominal wall stoma
   • Catheterisation via stoma (easier than urethral CIC)
   • Improves independence

5. Bladder Neck Procedures

   • Bladder neck reconstruction or sling to improve continence

Bowel Management:

• Goal: Achieve predictable, controlled bowel evacuation; prevent faecal incontinence and constipation
• Methods:
  • "Dietary: High fibre, adequate hydration"
  • "Laxatives: Polyethylene glycol (Movicol), senna"
  • "Suppositories/Enemas: Glycerin, phosphate enemas (scheduled)"
  • "Transanal Irrigation: Retrograde colonic irrigation systems (Peristeen)"
  • "Antegrade Continence Enema (ACE/Malone Procedure): Appendix brought to abdominal wall; antegrade enema flushes colon"
  • "Colostomy: Rarely required; end-stage option"

5. Orthopaedic Management

Goals:

• Maximize mobility and independence
• Prevent/correct deformities
• Facilitate bracing and assistive devices

Lower Limb Deformities:

1. Talipes Equinovarus (Clubfoot)

   • Initial: Ponseti method (serial casting + Achilles tenotomy)
   • Resistant cases: Surgical release (posteromedial release)

2. Hip Subluxation/Dislocation

   • Controversy: Whether to treat in non-ambulatory children
   • If ambulatory potential: Open reduction + femoral/pelvic osteotomy
   • If non-ambulatory: Usually not treated (may impair sitting balance if reduced)

3. Knee Contractures

   • Serial casting or bracing
   • Hamstring lengthening or quadricepsplasty

4. Foot Deformities

   • Ankle-foot orthoses (AFOs)
   • Surgical correction: Osteotomies, arthrodesis

Scoliosis:

• Incidence: 50-90% develop scoliosis by adolescence
• Monitoring: Spine X-rays every 6-12 months
• Management:
  • "less than 20° Cobb angle: Observation"
  • "20-40°: Bracing (TLSO) if skeletally immature"
  • "> 40-50°: Posterior spinal fusion with instrumentation"
• Special Consideration: Rule out tethered cord or shunt malfunction (may cause rapid curve progression)

Kyphosis:

• Severe gibbus deformity in thoracic lesions
• May compromise sitting, wound healing
• May require kyphectomy + spinal fusion

Mobility and Ambulation:

Ambulation potential correlates with lesion level: [10]

Physiotherapy:

• Early mobilization and strengthening
• Gait training with orthoses
• Wheelchair mobility training
• Contracture prevention (stretching, positioning)

6. Neurodevelopmental and Educational Support

• Early Intervention: Speech therapy, occupational therapy, developmental therapists (0-3 years)
• Educational Support: Individualized Education Plan (IEP); resource teaching
• Neuropsychological Assessment: Baseline at age 5; guide educational accommodations
• Management of Cognitive Deficits:
  • Executive function training
  • Attention deficit treatment (medications if ADHD diagnosed)
  • Assistive technology

7. Psychosocial and Family Support

• Family Counselling: Diagnosis, prognosis, expectations
• Peer Support Groups: Spina Bifida Association networks
• Mental Health Support: High rates of depression, anxiety in adolescents
• Sexuality and Reproductive Health: Addressing sexual function, contraception, pregnancy planning (females with spina bifida can conceive; require 5mg folic acid)
• Transition to Adult Care: Coordinated transfer at age 16-18 years

8. Surveillance for Late Complications

Tethered Cord Surveillance:

• Clinical assessment at each visit (motor function, bladder, pain)
• Spinal MRI if clinical concern or routine at ages 1, 5, 10, 15 years
• Surgical detethering if symptomatic

Renal Surveillance:

• Annual renal ultrasound and serum creatinine
• Urodynamics as clinically indicated
• Target: Bladder pressure less than 40 cm H₂O

Shunt Surveillance:

• Educate families on shunt malfunction symptoms
• Low threshold for imaging if concern
• Annual neurosurgical review

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8. Complications

Early Complications (Neonatal Period)

1. Meningitis/Ventriculitis

   • Risk if delayed closure or CSF leak
   • Organisms: E. coli, Klebsiella, S. aureus
   • Treatment: Prolonged IV antibiotics; CSF cultures

2. Wound Dehiscence

   • Occurs in 5-10% of repairs
   • Risk factors: Large defect, tension, infection
   • Management: Re-exploration, flap reconstruction

Intermediate Complications (Infancy to Childhood)

1. VP Shunt Malfunction (see above)
2. Symptomatic Chiari II Malformation (see above)
3. Latex Allergy (see above)
4. Urological Complications
   • Recurrent UTIs
   • Vesicoureteral reflux
   • Hydronephrosis → Chronic kidney disease
   • Bladder stones

Late Complications (Adolescence to Adulthood)

1. Tethered Cord Syndrome (see above)

2. Renal Failure

   • Leading cause of mortality in adults with spina bifida
   • Results from chronic high bladder pressures, reflux, recurrent infections
   • Prevalence: 10-20% develop chronic kidney disease; 3-5% progress to end-stage renal disease
   • Prevention: Strict adherence to CIC and anticholinergics

3. Obesity

   • Prevalence: 50-60% in adolescents/adults
   • Risk factors: Reduced mobility, altered metabolism
   • Consequences: Worsens mobility, pressure sores, metabolic syndrome

4. Pressure Sores (Decubitus Ulcers)

   • Insensate skin + prolonged pressure (wheelchair)
   • Sites: Ischial tuberosities, sacrum, heels
   • Prevention: Pressure-relieving cushions, regular repositioning, skin inspection

5. Sexual Dysfunction

   • Males: Erectile dysfunction (50-80%), ejaculatory dysfunction
   • Females: Reduced genital sensation, lubrication difficulties
   • Fertility: Usually preserved in both sexes (higher lesions may impair fertility)

6. Depression and Anxiety

   • Prevalence: 30-50% in adolescents/adults
   • Risk factors: Disability, incontinence, social isolation
   • Requires screening and mental health support

7. Social and Vocational Challenges

   • Educational underachievement (despite normal IQ in many)
   • Unemployment rates higher than general population
   • Reduced rates of marriage and independent living

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9. Prognosis and Outcomes

Survival

• Overall Survival: > 90% reach adulthood (significant improvement from less than 20% in pre-shunt era)
• Mortality Risk Factors:
  • Thoracic level lesions (higher mortality)
  • Severe hydrocephalus requiring multiple shunt revisions
  • Renal failure (leading cause of adult mortality)
  • Symptomatic Chiari II (brainstem dysfunction)

Causes of Death:

• Renal failure (30-40% of deaths)
• Shunt malfunction (20-30%)
• Respiratory complications (15-20%)
• Sepsis/infection (10-15%)

Ambulation

Lesion level is the primary predictor of walking ability: [10]

• Sacral (S1-S2): 90% independent community ambulators
• L5: 70% community ambulators (AFOs ± assistive device)
• L4: 50% household/limited community ambulators
• L3: 20-30% household ambulators (extensive bracing)
• L1-L2 or Thoracic: less than 10% ambulators (wheelchair dependent)

Factors Affecting Ambulation:

• Lesion level (most important)
• Presence/absence of hydrocephalus (shunted children have poorer motor outcomes)
• Orthopedic deformities (hip dislocation, severe scoliosis worsen ambulation)
• Obesity
• Motivation and access to physiotherapy

Continence

• Urinary Continence: 10-30% achieve social continence (dry for 3-4 hours) with CIC and medications
• Faecal Continence: 20-40% achieve continence with bowel management programs
• Quality of Life Impact: Incontinence is consistently rated as the most significant impact on quality of life by adolescents/adults with spina bifida

Cognitive and Educational Outcomes

• Intellectual Disability (IQ less than 70): 25-30%
• Average IQ: 80-90 (lower than general population mean of 100)
• Learning Disabilities: 60-80% require educational support
• School Completion: 70-80% complete high school (vs > 90% general population)
• University Attendance: 20-30%

Factors Affecting Cognition:

• Number of shunt revisions (each revision associated with ~3-5 point IQ decrease)
• Shunt infections (significant impact)
• Prenatal repair (MOMS trial showed trend toward improved cognition)

Independence and Quality of Life

• Independent Living: 30-50% live independently as adults
• Employment: 40-60% employed (vs 75-80% general population)
• Marriage: 20-30% marry
• Self-Reported Quality of Life: Variable; many adults report good quality of life despite physical limitations

Positive Prognostic Factors:

• Lower lesion level (sacral)
• Absence of or well-controlled hydrocephalus
• Normal or near-normal intelligence
• Supportive family environment
• Access to comprehensive multidisciplinary care
• Good urological management (preserved renal function)

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10. Evidence and Guidelines

Key Clinical Practice Guidelines

Landmark Evidence

1. Management of Myelomeningocele Study (MOMS) - NEJM 2011 [31]

• Design: Multicentre RCT (n=183); prenatal (19-25 weeks) vs postnatal repair
• Primary Outcome: Composite of death or VP shunt at 12 months
• Results:
  • "Shunt rate: 40% (prenatal) vs 82% (postnatal), pless than 0.001"
  • "Independent walking at 30 months: 42% vs 21%, p=0.01"
  • "Hindbrain herniation reversal: 36% vs 4%, pless than 0.001"
  • "Preterm birth: Mean 34 vs 37 weeks (maternal risk)"
• Conclusion: Prenatal repair reduces need for shunting and improves motor outcomes but increases maternal/fetal risks (preterm birth)
• Impact: Established prenatal repair as an option in specialist centres; changed standard of care

2. MRC Vitamin Study - Lancet 1991 [22]

• Design: Multicentre RCT (n=1817 women with previous NTD pregnancy); 4 mg folic acid vs placebo
• Result: 72% reduction in NTD recurrence (1.0% vs 3.5%, RR 0.28)
• Conclusion: Folic acid prevents NTDs in high-risk women
• Impact: Led to global folic acid supplementation recommendations and fortification programs

3. Long-term MOMS Outcomes - JAMA Pediatrics 2021 [39]

• Follow-up: School-age outcomes (6-9 years) from MOMS trial
• Results:
  • "Prenatal repair group: Better motor function, fewer shunt revisions"
  • No difference in cognitive outcomes at school age
  • Confirms durability of prenatal repair benefits

4. Fetoscopic vs Open Prenatal Repair - Multiple Studies 2020-2024 [32,33]

• Design: Observational cohorts comparing fetoscopic percutaneous repair to open hysterotomy
• Results:
  • "Fetoscopic: Later delivery (36 vs 34 weeks), less maternal morbidity"
  • "Shunt rates: Similar (30-50% both techniques)"
  • "Motor outcomes: Comparable"
• Conclusion: Fetoscopic approach may reduce maternal risks while maintaining fetal benefits
• Status: Ongoing RCTs to definitively compare techniques

5. Natural History of Spina Bifida - Nature Reviews Disease Primers 2015 [2]

• Comprehensive Review: Epidemiology, pathophysiology, management, outcomes
• Key Data:
  • "Hydrocephalus: 80-90% require shunting"
  • "Ambulation: Strongly level-dependent (see prognosis section)"
  • "Renal failure: Leading cause of adult mortality"
• Impact: Seminal reference for understanding spina bifida across lifespan

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11. Patient and Layperson Explanation

What is Spina Bifida?

Spina bifida literally means "split spine" in Latin. It occurs very early in pregnancy—within the first month, often before a woman even knows she is pregnant. Normally, the baby's spinal cord forms inside a protective tube made of bone (the spine). In spina bifida, this tube doesn't close all the way, leaving a gap. In severe cases (called myelomeningocele), the spinal cord and nerves poke out through this gap and are exposed.

What Causes It?

We don't know the exact cause, but we know it happens when the baby's neural tube (which becomes the brain and spinal cord) doesn't close properly in the first 28 days of pregnancy. The main risk factor is not getting enough folic acid (a B vitamin) before and during early pregnancy. That's why all women who could become pregnant are advised to take a folic acid supplement.

What Does This Mean for My Baby?

The severity depends on the type of spina bifida:

• Spina Bifida Occulta ("hidden"): A small gap in the spine bones, but the spinal cord is normal. Often causes no problems and is found by accident on X-rays.

• Myelomeningocele ("open spina bifida"): The most severe type. The spinal cord is damaged, which causes:

  • Weakness or paralysis in the legs (how much depends on where the gap is—higher up on the back means more paralysis)
  • No feeling in the legs and feet (risk of injuries and pressure sores)
  • Bladder and bowel problems (can't control going to the toilet)
  • Fluid build-up in the brain (hydrocephalus) in 8 out of 10 babies—this needs a tube (shunt) to drain the fluid

Is Surgery Needed?

Yes. If the baby has an open spina bifida:

1. Surgery Soon After Birth: We operate within 1-2 days to close the opening in the back. This prevents infection, but it cannot repair the nerve damage that has already happened.

2. Brain Surgery for Hydrocephalus: Most babies need a thin tube (VP shunt) placed inside the brain to drain extra fluid down into the tummy. This tube stays in for life, but it can block or get infected, so it sometimes needs to be replaced.

3. Some Babies Can Have Surgery Before Birth: In specialized hospitals, surgeons can repair the opening while the baby is still in the womb (around 20-25 weeks of pregnancy). This is major surgery and risky for the mother, but it can reduce brain fluid build-up and help the baby's legs work better.

What About the Bladder?

Because the nerves to the bladder are damaged, most children with spina bifida cannot pee normally. The bladder doesn't empty, which can damage the kidneys. To prevent this:

• Parents (and later the child) insert a small, soft tube (catheter) into the bladder several times a day to drain urine. This is called "clean intermittent catheterization" or CIC.
• Medicines may be needed to relax the bladder.
• This protects the kidneys and can help the child stay dry.

Will My Child Walk?

It depends on where the gap in the spine is:

• Gap in the lower back (sacral area): Good chance of walking normally or with minor support.
• Gap higher up (lumbar area): May walk with leg braces, crutches, or a walker, or may need a wheelchair.
• Gap very high (thoracic): Will need a wheelchair.

Physical therapy and special leg braces help children move as much as possible.

What is the "Shunt" Everyone Talks About?

The shunt is a thin plastic tube placed in the brain to drain extra fluid. One end sits in the fluid space inside the brain, and the other end tunnels under the skin down to the belly, where the fluid is absorbed. If the shunt blocks or gets infected, the child gets headaches, vomiting, and drowsiness—this is an emergency and needs urgent hospital treatment.

Important Safety Issue: Latex Allergy

Many children with spina bifida develop a serious allergy to latex (rubber). This is because they have many surgeries and use latex catheters. Always tell doctors, nurses, and dentists about this allergy. They must use latex-free gloves and equipment.

What About School and Learning?

Many children with spina bifida have normal intelligence, but some need extra help at school. This is often because of the fluid build-up in the brain or repeated shunt problems. Speech, memory, and concentration can be affected. Educational support and occupational therapy can help.

Can This Be Prevented?

Yes—to a large degree. If all women take a folic acid supplement (400 micrograms daily) starting before they get pregnant and continuing through the first 12 weeks, the risk of spina bifida drops by about 70%. Women who have had a baby with spina bifida, or who have diabetes or epilepsy, need a higher dose (5 milligrams daily).

What is the Long-Term Outlook?

With modern medical care, over 90% of children with spina bifida live into adulthood. They face challenges—multiple surgeries, bladder and bowel management, mobility limitations—but many lead fulfilling lives, go to university, work, and have families. The key is consistent, expert medical follow-up throughout life to prevent complications, especially kidney damage.

Where Can I Get Support?

• Spina Bifida Association (USA): spinabifidaassociation.org
• SHINE (UK - Spina Bifida · Hydrocephalus · Information · Networking · Equality): shinecharity.org.uk
• Local Spina Bifida Clinics: Multidisciplinary teams with specialists in neurosurgery, urology, orthopedics, and more

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12. Examination Focus (MRCPCH, FRCS Paediatrics, MRCOG)

High-Yield Exam Topics

1. Prevention

• Q: What dose of folic acid for a woman with epilepsy taking valproate?
• A: 5 mg daily (high-dose; commence pre-conception and continue until 12 weeks)

2. Antenatal Diagnosis

• Q: What are the "lemon sign" and "banana sign" on fetal ultrasound?
• A:
  • "Lemon sign: Scalloping of frontal bones (frontal concavity)"
  • "Banana sign: Abnormal cerebellar shape (wraps around brainstem) with obliterated cisterna magna"
  • Both indicate Chiari II malformation associated with myelomeningocele

3. Associated Brain Malformation

• Q: What brain malformation is universally associated with myelomeningocele?
• A: Arnold-Chiari Type II malformation (cerebellar vermis and medulla herniate through foramen magnum; causes hydrocephalus)

4. Latex Allergy

• Q: Why are spina bifida patients at high risk of latex allergy?
• A: Repeated early exposure to latex during multiple surgeries and daily clean intermittent catheterisation; 50-73% develop type I hypersensitivity. Always use latex-free equipment.

5. Shunt Malfunction

• Q: A 4-year-old with spina bifida and a VP shunt presents with vomiting and headache. Most likely diagnosis?
• A: VP shunt malfunction (obstruction or infection)—requires urgent CT head and neurosurgical assessment

6. Urological Management

• Q: What is the cornerstone of neurogenic bladder management in spina bifida?
• A: Clean Intermittent Catheterisation (CIC) performed 4-6 times daily to prevent high bladder pressures and renal damage

7. Tethered Cord Syndrome

• Q: A 10-year-old with repaired spina bifida has new-onset back pain and deteriorating walking. What is the likely diagnosis?
• A: Tethered cord syndrome—spinal cord tethered at repair site; stretched during growth; requires MRI spine and surgical detethering

8. MOMS Trial

• Q: What is the MOMS trial, and what did it show?
• A: Randomized trial comparing prenatal vs postnatal myelomeningocele repair. Prenatal repair reduced shunt rate from 82% to 40% and improved motor outcomes but increased preterm birth risk.

Viva Voce Scenarios

Scenario 1: Newborn with Lumbosacral Lesion

Examiner: "You are called to the delivery room. A baby has just been born with a large lumbosacral mass. What do you do?"

Model Answer:

1. Immediate Management:

   • Position baby prone or lateral to avoid pressure on lesion
   • Cover lesion with sterile saline-soaked non-adherent gauze and plastic wrap
   • Establish latex-free environment (all staff)
   • Avoid rectal examination or thermometer (risk of meningitis)
   • Keep baby warm (incubator)

2. Assessment:

   • Examine lesion: size, location, skin coverage, CSF leak, visible neural tissue
   • Neurological examination: lower limb tone, movement, reflexes (determine level)
   • Measure occipitofrontal circumference (OFC)
   • Palpate fontanelle (assess for hydrocephalus)
   • Check for other anomalies

3. Investigations:

   • Cranial ultrasound (ventricular size)
   • Renal ultrasound (hydronephrosis)
   • MRI brain and spine (when stable)

4. Management:

   • IV antibiotics (ampicillin + gentamicin) to cover until surgical closure
   • NBM (nil by mouth) if surgery planned
   • Neurosurgical referral for closure within 24-72 hours
   • Multidisciplinary team involvement (neurosurgery, urology, orthopaedics, physiotherapy)
   • Family counselling (prognosis, long-term needs)

Examiner: "Why is the baby latex-allergic?" Answer: Not allergic at birth, but will develop allergy due to repeated latex exposure during surgeries and CIC; preventive measure to avoid sensitization.

Scenario 2: Prenatal Counselling

Examiner: "A 22-week pregnant woman has just been told her baby has myelomeningocele at the L4 level. What do you tell her?"

Model Answer:

1. Diagnosis Confirmation: Explain ultrasound findings (splayed vertebrae, lemon/banana signs, ventriculomegaly); recommend fetal MRI for detailed assessment.

2. Prognosis:

   • Survival: > 90% survive to adulthood with modern care
   • Hydrocephalus: 80-90% will need VP shunt
   • Mobility: L4 lesion—likely limited community ambulation with ankle-foot orthoses and assistive devices; may need wheelchair for longer distances
   • Bladder/Bowel: Will require CIC and bowel management
   • Cognition: Many have normal intelligence but some learning difficulties common (related to hydrocephalus)

3. Treatment Options:

   • Prenatal Repair (if eligible and interested):
     • Specialized fetal surgery at 19-25 weeks
     • Reduces shunt need from ~80% to ~40%
     • Improves walking outcomes
     • Risks: Preterm birth (average 34 weeks), uterine scar requiring cesarean in future pregnancies
   • Postnatal Repair (standard):
     • Surgery within 24-72 hours after birth to close defect
     • Shunt placement if hydrocephalus develops
     • Lifelong multidisciplinary care

4. Ongoing Needs: Multiple surgeries, CIC for bladder, physiotherapy, orthopedic interventions, educational support.

5. Termination: Acknowledge this is an option; provide non-directive counselling; respect patient autonomy.

6. Support: Connect with spina bifida support groups, specialist fetal medicine and neurosurgical teams.

Clinical Examination Stations (OSCE/PACES)

Station: Examine this Child's Spine

Instructions: "This is a 6-year-old child with a history of back surgery as a baby. Please examine the spine."

Examination Approach:

1. Inspection (Child Standing, if able; otherwise sitting/prone):

   • Scar: Midline lumbosacral scar (myelomeningocele repair); look for skin changes (hairy patch, lipoma, sinus—suggests tethered cord)
   • Spine alignment: Scoliosis (rib hump, shoulder asymmetry), kyphosis
   • Skin: Cafe-au-lait spots (neurofibromatosis), sacral dimple, hair tuft

2. Palpation:

   • Palpate spinous processes (gaps, tenderness, step-off)
   • Scar palpation (tethering, lipoma)

3. Range of Movement:

   • Cervical, thoracic, lumbar flexion/extension (if able)

4. Neurological Examination Lower Limbs:

   • Tone: Flaccid paralysis below lesion level
   • Power: Test myotomes (L2: hip flexion; L3: knee extension; L4: ankle dorsiflexion; L5: great toe extension; S1: ankle plantarflexion)
   • Reflexes: Absent knee and ankle jerks below lesion
   • Sensation: Map sensory level (may have bathing trunk anaesthesia)
   • Perianal sensation and anal wink (S2-S4 sacral segments)

5. Gait (if child ambulatory):

   • Observe walking (with/without orthoses and aids)
   • Note foot drop, circumduction, Trendelenburg gait

6. Look for Associated Features:

   • Head: Enlarged OFC (hydrocephalus); shunt scar (behind ear, along neck, chest)
   • Limbs: Foot deformities (clubfoot, cavovarus), hip dislocation, muscle wasting
   • Wheelchair/orthoses nearby

Presentation: "This child has a midline lumbosacral scar consistent with repaired myelomeningocele. There is flaccid paralysis of the lower limbs with absent power below L4, absent reflexes, and sensory loss below the knees, in keeping with an L4 level lesion. I note ankle-foot orthoses, suggesting limited ambulatory capacity. There is a scoliosis present. I would assess for hydrocephalus by measuring OFC and examining for a VP shunt scar. This child requires multidisciplinary follow-up including neurosurgery, urology (for neurogenic bladder management with CIC), orthopaedics (scoliosis monitoring), and physiotherapy."

Short Answer Questions (SAQs)

Q1: List 5 risk factors for neural tube defects. A:

1. Inadequate folic acid intake
2. Maternal diabetes (pre-existing)
3. Maternal obesity (BMI > 30)
4. Sodium valproate use in pregnancy
5. Previous pregnancy affected by NTD

Q2: Describe the components of the "two-hit hypothesis" in myelomeningocele. A:

• First hit: Primary failure of neural tube closure during neurulation (days 21-28)
• Second hit: Progressive secondary damage to exposed neural placode from mechanical trauma and amniotic fluid chemical injury throughout gestation
• Prenatal repair aims to prevent the second hit

Q3: What are the indications for surgical detethering in tethered cord syndrome? A:

• New or progressive motor weakness
• Urological deterioration (worsening incontinence, hydronephrosis, recurrent UTIs)
• Progressive scoliosis
• New-onset pain (back, leg, radicular)
• MRI evidence of low-lying conus medullaris (below L2-L3) with thick filum terminale

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13. References

Primary Literature

1. Phillips LA, Burton JM, Evans SH. Spina Bifida Management. Curr Probl Pediatr Adolesc Health Care. 2017;47(7):173-177. PMID: 28734746

2. Copp AJ, Adzick NS, Chitty LS, Fletcher JM, Holmbeck GN, Shaw GM. Spina bifida. Nat Rev Dis Primers. 2015;1:15007. PMID: 27189655

3. Rocque BG, Hopson BD, Blount JP. Caring for the Child with Spina Bifida. Pediatr Clin North Am. 2021;68(4):915-927. PMID: 34247717

4. Akalan N. Myelomeningocele (open spina bifida) - surgical management. Adv Tech Stand Neurosurg. 2011;37:113-141. PMID: 21997743

5. Kancherla V. Neural tube defects: a review of global prevalence, causes, and primary prevention. Childs Nerv Syst. 2023;39(7):1703-1710. PMID: 36882610

6. Greene ND, Copp AJ. Neural tube defects. Annu Rev Neurosci. 2014;37:221-242. PMID: 25032496

7. McCoy AR, Singerman L, Anand N, Kanallakan A. Spina Bifida. Phys Med Rehabil Clin N Am. 2025;36(3):641-660. PMID: 40581437

8. Khalil A, Caric V, Papageorghiou A, Bhide A, Akolekar R, Thilaganathan B. Prenatal prediction of need for ventriculoperitoneal shunt in open spina bifida. Ultrasound Obstet Gynecol. 2014;43(2):157-161. PMID: 24006252

9. Copp AJ, Adzick NS, et al. Spina bifida. Nat Rev Dis Primers. 2015;1:15007. PMID: 27189655

10. Houtrow AJ, MacPherson C, Jackson-Coty J, et al. Prenatal Repair and Physical Functioning Among Children With Myelomeningocele: A Secondary Analysis of a Randomized Clinical Trial. JAMA Pediatr. 2021;175(4):e205674. PMID: 33555337

11. Adzick NS, Thom EA, Spong CY, et al; MOMS Investigators. A randomized trial of prenatal versus postnatal repair of myelomeningocele. N Engl J Med. 2011;364(11):993-1004. PMID: 21306277

12. Kancherla V. Neural tube defects: a review of global prevalence, causes, and primary prevention. Childs Nerv Syst. 2023;39(7):1703-1710. PMID: 36882610

13. Greene ND, Copp AJ. Neural tube defects. Annu Rev Neurosci. 2014;37:221-242. PMID: 25032496

14. Zaganjor I, Sekkarie A, Tsang BL, et al. Describing the Prevalence of Neural Tube Defects Worldwide: A Systematic Literature Review. PLoS One. 2016;11(4):e0151586. (Related evidence base)

15. Viswanathan M, Urrutia RP, Hudson KN, Middleton JC, Kahwati LC. Folic Acid Supplementation to Prevent Neural Tube Defects: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2023;330(5):460-469. PMID: 37526714

16. Crider KS, Qi YP, Yeung LF, et al. Folic Acid and the Prevention of Birth Defects: 30 Years of Opportunity and Controversies. Annu Rev Nutr. 2022;42:423-452. PMID: 35995050

17. Stothard KJ, Tennant PW, Bell R, Rankin J. Maternal overweight and obesity and the risk of congenital anomalies: a systematic review and meta-analysis. JAMA. 2009;301(6):636-650. (Related evidence)

18. Correa A, Gilboa SM, Besser LM, et al. Diabetes mellitus and birth defects. Am J Obstet Gynecol. 2008;199(3):237.e1-9. (Related evidence)

19. Weston J, Bromley R, Jackson CF, et al. Monotherapy treatment of epilepsy in pregnancy: congenital malformation outcomes in the child. Cochrane Database Syst Rev. 2016;11:CD010224. (Related evidence)

20. Moretti ME, Bar-Oz B, Fried S, Koren G. Maternal hyperthermia and the risk for neural tube defects in offspring. Epidemiology. 2005;16(2):216-219. (Related evidence)

21. MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991;338(8760):131-137. (Landmark study - recurrence prevention)

22. MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991;338(8760):131-137. PMID: 1677062

23. Crider KS, et al. Folic Acid and the Prevention of Birth Defects: 30 Years of Opportunity and Controversies. Annu Rev Nutr. 2022;42:423-452. PMID: 35995050

24. Greene ND, Copp AJ. Neural tube defects. Annu Rev Neurosci. 2014;37:221-242. PMID: 25032496

25. Copp AJ, Greene ND. Genetics and development of neural tube defects. J Pathol. 2010;220(2):217-230. (Related embryology)

26. Stevenson KL. Chiari Type II malformation: past, present, and future. Neurosurg Focus. 2004;16(2):E5. (Related evidence)

27. Meller C, Covini D, Aiello H, et al. Update on prenatal diagnosis and fetal surgery for myelomeningocele. Arch Argent Pediatr. 2021;119(3):e207-e214. PMID: 34033426

28. Oakes WJ. Management of Chiari II complications. Neurosurg Clin N Am. 1995;6(2):293-301. (Related evidence)

29. Bowman RM, McLone DG, Grant JA, Tomita T, Ito JA. Spina bifida outcome: a 25-year prospective. Pediatr Neurosurg. 2001;34(3):114-120. (Related evidence - tethered cord)

30. Paulsen AH, Lundar T, Lindegaard KF. Twenty-year outcome in young adults with childhood hydrocephalus: assessment of surgical outcome, work participation, and health-related quality of life. J Neurosurg Pediatr. 2010;6(6):527-535. (Related evidence - shunt outcomes)

31. Adzick NS, Thom EA, Spong CY, et al; MOMS Investigators. A randomized trial of prenatal versus postnatal repair of myelomeningocele. N Engl J Med. 2011;364(11):993-1004. PMID: 21306277

32. Corroenne R, Rangwani S, Whitehead WE, et al. Neurodevelopmental Outcomes after Fetoscopic Myelomeningocele Repair. J Pediatr. 2025;268:113919. PMID: 39828055

33. Miller JL, Groves ML, Baschat AA. Fetoscopic spina bifida repair. Minerva Ginecol. 2019;71(2):163-167. PMID: 30486637

34. Pastuszka A, Koszutski T, Horzelska E, et al. Absence of a Hernia Sack in Patients Undergoing Prenatal Repair of Spina Bifida Increases the Risk of Developing Shunt-Dependent Hydrocephalus. Diagnostics (Basel). 2023;13(3):350. PMID: 36766448

35. Stein R, Bogaert G, Dogan HS, et al. EAU/ESPU guidelines on the management of neurogenic bladder in children and adolescent part I diagnostics and conservative treatment. Neurourol Urodyn. 2020;39(1):45-57. PMID: 31724222

36. Fairchild RJ, Aksenov LI, Hobbs KT, et al. Medical management of neurogenic bladder in patients with spina bifida: A scoping review. J Pediatr Urol. 2023;19(1):21-29. PMID: 36323597

37. US Preventive Services Task Force; Barry MJ, Nicholson WK, et al. Folic Acid Supplementation to Prevent Neural Tube Defects: US Preventive Services Task Force Reaffirmation Recommendation Statement. JAMA. 2023;330(5):454-459. PMID: 37526713

38. Stein R, Bogaert G, Dogan HS, et al. EAU/ESPU guidelines on the management of neurogenic bladder in children and adolescent part I diagnostics and conservative treatment. Neurourol Urodyn. 2020;39(1):45-57. PMID: 31724222

39. Houtrow AJ, MacPherson C, Jackson-Coty J, et al. Prenatal Repair and Physical Functioning Among Children With Myelomeningocele: A Secondary Analysis of a Randomized Clinical Trial. JAMA Pediatr. 2021;175(4):e205674. PMID: 33555337

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