Overview
Definition:
Myelomeningocele, the most severe form of spina bifida, is a congenital condition where the spinal cord and meninges protrude through an opening in the vertebral column, typically in the lumbosacral region
This exposure leads to neurological deficits and increases the risk of infection and further damage.
Epidemiology:
The incidence of neural tube defects (NTDs), including myelomeningocele, has declined significantly in many regions due to folic acid fortification programs, but still remains a concern
Prevalence varies geographically and ethnically, with some studies indicating an incidence of 0.5-1 per 1,000 live births in certain populations
Risk factors include maternal folate deficiency, certain medications, and genetic predisposition.
Clinical Significance:
Myelomeningocele is a serious condition requiring immediate and multidisciplinary management
The extent of neurological damage directly impacts the child's lifelong mobility, bowel and bladder function, and risk of hydrocephalus
Timely surgical intervention is crucial to prevent infection, protect neural tissue, and optimize functional outcomes, making it a critical topic for pediatric residents preparing for DNB and NEET SS exams.
Delivery Considerations
Prenatal Diagnosis:
Diagnosis often occurs antenatally via ultrasound and maternal serum alpha-fetoprotein (MSAFP) screening
Fetal MRI can further delineate the defect
This allows for planning of delivery at a specialized center with a multidisciplinary team.
Delivery Mode:
While vaginal delivery can be considered, elective Cesarean section is often recommended to minimize trauma to the exposed neural tissue and reduce the risk of infection and mechanical damage
Delivery should occur at a tertiary care center equipped for neonatal surgery.
Timing Of Delivery:
Delivery is typically planned after 34 weeks gestation if antenatally diagnosed, to allow for fetal lung maturity and surgical readiness
However, spontaneous preterm labor may necessitate earlier intervention.
Team Preparation:
A multidisciplinary team including neonatologists, pediatric surgeons, anesthesiologists, neurologists, and nurses should be available at the time of delivery
Communication and coordinated care are paramount.
Sterile Handling And Initial Care
Immediate Postnatal Assessment:
A thorough assessment of the neonate, including vital signs, general condition, and examination of the myelomeningocele defect (size, location, presence of sac, any associated anomalies), is performed
The defect is inspected visually without palpation.
Defect Protection:
The exposed neural tissue must be kept moist and sterile to prevent infection and drying
The defect is typically covered with sterile, saline-moistened gauze or a non-adherent dressing
Avoid applying any ointments or antiseptics directly to the neural elements.
Infection Prevention:
Strict aseptic techniques are essential
The neonate should be isolated if possible
Antibiotics are usually initiated prophylactically to prevent meningitis and wound infection.
Temperature Management:
Maintaining normothermia is crucial, as infants with myelomeningocele can be prone to hypothermia
The infant should be kept in a warmer and appropriately dressed.
Bowel And Bladder Management:
Initial management involves keeping the defect clean and dry
Urine may accumulate in the bladder due to impaired innervation
gentle catheterization may be necessary if distension is significant
Stool management is also a consideration due to potential sphincter dysfunction.
Early Surgical Closure
Indications For Closure:
Surgical closure is indicated in virtually all neonates with myelomeningocele to prevent infection, further neural damage, and hydrocephalus
The timing is typically within the first 72 hours of life.
Surgical Procedures:
The goal is to close the defect and cover the exposed neural elements with healthy, well-vascularized tissue
Procedures include primary skin closure, rotational flaps, or tissue grafting, depending on the size and location of the defect
Excision of redundant meningeal sac and cerebrospinal fluid (CSF) leak repair may be necessary.
Anesthetic Considerations:
General anesthesia is used
Careful positioning is required to protect the surgical site
Monitoring includes standard anesthetic monitoring, with attention to potential associated conditions like Chiari II malformation.
Preoperative Preparation:
This includes stabilizing the infant, initiating antibiotics, and ensuring adequate hydration
Imaging may be performed if indicated to assess for hydrocephalus or other anomalies
A coordinated approach involving the surgical and nursing team is vital.
Postoperative Care:
Postoperative care involves meticulous wound care, continued infection prevention, pain management, and monitoring for CSF leak or wound dehiscence
The infant is typically kept on their side or abdomen to relieve pressure on the closure site
Monitoring for hydrocephalus is essential, and CSF shunting may be required.
Associated Conditions
Hydrocephalus:
Chiari II malformation, characterized by downward displacement of the cerebellar tonsils and brainstem through the foramen magnum, is almost universally present in myelomeningocele
This often leads to obstructive hydrocephalus, requiring ventriculoperitoneal (VP) shunting.
Orthopedic Abnormalities:
Clubfoot (talipes equinovarus) is common
Hip dislocation, scoliosis, and other spinal deformities can also occur, requiring early orthopedic assessment and intervention.
Genitourinary Dysfunction:
Neurogenic bladder and bowel are frequent sequelae due to impaired innervation of the sphincter mechanisms
This necessitates long-term management to prevent renal damage and manage continence issues.
Neurological Deficits:
Motor and sensory deficits below the level of the lesion are expected
The extent of these deficits influences the child's long-term functional prognosis and need for assistive devices.
Key Points
Exam Focus:
DNB and NEET SS questions will focus on the principles of sterile handling, timing of surgical closure, common associated anomalies (Chiari II, hydrocephalus, neurogenic bladder), and immediate postnatal care
Understanding the rationale behind Cesarean delivery vs
vaginal delivery is also crucial.
Clinical Pearls:
Never palpate the myelomeningocele defect directly
Maintain strict aseptic technique
Recognize the high incidence of hydrocephalus and the need for early VP shunt if indicated
Multidisciplinary team approach is key to optimal outcomes.
Common Mistakes:
Applying occlusive dressings to the defect, inadequate sterile handling, delaying surgical closure beyond 72 hours, and neglecting the workup for hydrocephalus are common pitfalls to avoid
Misinterpreting the urgency of infection prevention can lead to severe complications.