Medical Care
The newborn with an open neural tube defect (NTD) should be kept warm and the defect covered with a sterile wet saline dressing. The patient should be positioned in the prone position to prevent pressure on the defect. [30]
Surgical Care
Neurosurgical intervention is the mainstay of treatment for open neural tube defects (NTDs); closed NTDs typically do not warrant urgent surgery.
The newborn with an open NTD should be kept warm and the defect covered with a sterile wet saline dressing, with consideration for prophylactic antibiotics. The patient should be positioned in the prone position to prevent pressure on the defect. Prompt closure of the defect is indicated, ideally within the first 72 hours after birth for myelomeningocele. The closure involves classic neurosurgical techniques, involving the approximation of the lateral edges of the open neural plate to form a neural tube; this covers the open caudal end of the spinal cord with a layer of pia mater. [30] For closed defects associated with cord tethering, surgery involves removal of structures that are anchoring the cord.
In children born with severe hydrocephalus, a ventriculoperitoneal shunt placement should be considered at the time of myelomeningocele closure. However, this view is debated given potential differences in complications such as rate of infection and CSF leak, as well as considerations such as length of hospital stay and wound morbidity. [31] 41 Although simultaneous repair is often not feasible in developing countries, which have higher rates of hydrocephalus and are more likely to present at more delayed and/or advanced stages, patients with co-occurring hydrocephalus should undergo shunt placement 5–10 days following myelomeningocele closure (provided they have sterile CSF). [32] Patients with mild to moderate ventriculomegaly are observed closely for increased intracranial pressure, including bradycardia, bulging fontanelles, poor feeding, vomiting, irritability, lethargy, sundowning of the eyes, and/or apnea. A subgaleal shunt can be placed temporarily in pre-term infants. Third ventriculostomy is a procedure more common in developing countries, but still rarely performed, where access to follow-up or tertiary care is limited. [33]
Patients presenting with symptomatic Chiari II malformations (see image below), are closely correlated with myelomeningoceles. The classic treatment of suboccipital craniectomy with duraplasty and decompression of the posterior fossa and cerebellar tonsils is rarely done in patients with Chiari II malformation.
Child with Chiari malformation, in whom the tonsils have descended to the level of C2.
Children with syrinx (see following images) and previous open lumbar defect usually mandate revision for tethered cord. In some cases posterior fossa decompression is needed as for Chiari I malformation. In rare cases a syringosubarachnoid stent to divert the CSF from the central canal is needed.
Spinal cord tethering (sometimes associated with myelomeningoceles or lipomeningocele) may cause progressive neurologic deterioration. Untethering procedures are required for those with significant and progressive impairment, characterized by growth and/or flexion of the vertebral column and stretching the tetherd cord.
Improvements and increased frequency in maternal screening (i.e., serum and ultrasound) have enabled early intervention. Fetal surgery before 26 weeks' gestation has been performed with the aim of reducing development of Arnold-Chiari malformations and eventually hydrocephalus; fetal surgery for myelomeningocele can prevent excess CSF loss from the back and therefore prevent Chiari II malformation, hydrocephalus, and syringomyelia. Investigators for the Management of Myelomeningocele Study (MOMS) demonstrated the success of in utero surgical repair for open NTDs. [34] This prospective randomized controlled trial compared fetuses with prenatally diagnosed myelomeningocele treated via standard postnatal repair vs in utero. Outcomes demonstrated a significant reduction in hydrocephalus, and thus need for ventriculoperitoneal shunt, and decreased incidence of Chiari malformation. There was also improvement in spinal-neurologic functional outcomes as motor skills were superior in the fetal surgery group, and twice as many children were ambulating independently at 2.5 years of age relative to the post-natal surgery group. However, maternal complications were also observed, such as pre-term birth, placental abruption, need for future caesarean delivery, among others within the surgical cohort. Overall the trial demonstrated more favorable outcomes from pre-natal treatment beyond the maternal risks from surgery.
Since publication of the MOMS trial results, fetal myelomeningocele repair has become a standard of care option for prenatally diagnosed patients. [35] As such, increased demand for this procedure was observed. However, a growing concern in the “post-MOMS” era for women carrying a subsequent pregnancy is uterine dehiscence and rupture, as well as a requirement for caesarean delivery for subsequent pregnancies. Imaging techniques such as magnetic resonance imaging or sonographic evaluation of uterine wall thickness have been used to evaluate post-operative hysterotomy scarring and integrity. Due to these concerns for open prenatal surgery on maternal morbidity, minimally invasive techniques using fetoscopy have been developed, and are becoming increasingly popular worldwide. [36] Compared to traditional open repair (requiring hysterotomy), fetoscopic repair is via laparoscopy. While there is a clear benefit in avoiding hysterotomy, notable risks include preterm premature membrane rupture, premature delivery, and inadequate coverage of the NTD (leading to CSF leak, possible Chiari malformation, and infection). [37] Comparative studies between open repair and fetoscopic techniques have thus far been equivocal, however, further development of the fetoscopic approach and techniques may ultimately lead to improved outcomes. [38, 39]
Consultations
Consultation with the following may prove helpful:
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Neurosurgeon
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Urologist
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Orthopedist
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Physical therapist
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Plastic surgeon (in some cases)
Activity
Activity is limited by the degree of involvement.
Prevention
The addition of nutrients (notably folic acid, vitamin C, and riboflavin) to common foods, such as cereals and grain products, has significantly decreased the incidence of neural tube defects (NTDs) globally. Notably, adequate levels of folate intake are important during the first month of pregnancy, particularly given the early phases of neurulation. The metabolic pathways and role of folate in neurulation remains unclear, however, studies have demonstrated that folate has a direct role in neural tube closure. [40]
Conversely, lack of folate and/or defects in the enzymes involved in folate metabolism are correlated with higher rates of NTDs. [41]
This is why all pregnant women, women who are planning pregnancy, and women who may become pregnant, are recommended to consume 400 mcg of folate daily in most countries, particularly developing countries. Otherwise, there is a chance that by the time they inadvertently find out they are pregnant (i.e., anticipated start of the next menstrual cycle), there is already a critical period of missed nutrition.
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Myelomeningocele in a newborn.
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Myelomeningocele in a newborn - Lateral view.
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Child with Chiari malformation, in whom the tonsils have descended to the level of C2.
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MRI of a cervical syrinx in the sagittal plane.
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MRI of a cervical syrinx in the axial plane.
