Presentation of Myelomeningoceles in Children

Symptoms

The typical anomalies associated with myelomeningocele include the spinal defect, Chiari II malformation, and hydrocephalus.

Myelomeningocele

• Dorsal midline sac: A midline fluid-filled sac is present that extends from the spinal canal. There are no posterior elements extending from the sac level and no neural elements below. The end of the spinal cord ends in the superior (rostral) wall of the sac as the placode. The posterior (dorsal) aspect of the placode is the inside of the neural tube, and the anterior (ventral) aspect is the normal exterior surface of the spinal cord with residual roots extending vertically toward the spinal cord.
• CSF leakage: The sac is filled with CSF. If it is leaking, there is an increased risk of infection.

Chiari II malformations

• Symptomatic hindbrain compression: Chiari II malformation is present in some form in all children with myelomeningoceles. Symptomatic hindbrain compression requiring posterior fossa decompression can occur in neonates, but these symptoms often resolve with shunting or shunt revision (21, 37). 
• Late symptoms usually due hydrocephalus: Chiari II Malformation symptoms including symptoms of brainstem dysfunction and hindbrain compression that present later in life are usually due to shunt malfunction.

Hydrocephalus

• Development or progression after closure: Hydrocephalus is present in 10–15 % of newborns with myelomeningocele prior to closure of the defect. In most children hydrocephalus progresses after closure of the defect.
• Enlarging head or leakage from myelomeningocele repair: Developing hydrocephalus is typically associated with CSF leakage from the wound, but it may also cause acceleration in the infant’s head growth.

Intervention

Stabilization

• Usually stable: At birth the infant is usually stable unless there are signs of lower brainstem dysfunction due to Chiari II malformation; in this case, hydrocephalus will need to be treated promptly. While myelomeningocele closure is not an emergent procedure, excessive delay, particularly in cases with rupture of the sac and CSF leak, is not advisable.
• Evaluate for terminal deformities: Fatal genetic abnormalities like trisomy 18 or cardiac abnormalities that would preclude surgery should be identified.

Preparation for definitive intervention, nonemergent

• Vascular access: Vascular access via umbilical lines or other vascular access devices should be established preoperatively.
• Vitamin K: The administration of vitamin K per standard protocol is important in neonatal surgery.
• Cardiac screening: If a detailed fetal echocardiogram was performed and the infant is clinically stable, there is no need for postnatal echocardiogram. Otherwise, it is advisable to obtain one prior to myelomeningocele repair.
• Imaging: Spine x-ray may reveal a concomitant dysraphic spinal lesion or split cord malformations.
• Hydrocephalus assessment: Enlightened by the head circumference and the initial cranial imaging, judgment regarding the presence of definitive hydrocephalus would influence the operative plan. A small number of children have hydrocephalus at birth, while most other children develop the clinical manifestations of hydrocephalus after myelomeningocele closure.
• IV antibiotics: Prophylactic antibiotic coverage should be started with broad-spectrum coverage (e.g., ampicillin plus gentamicin).

Preparation for definitive intervention, emergent

 

• Hydrocephalus: Shunt placement should not be delayed if there is clear symptomatic hydrocephalus.

 

Admission Orders

• HOB, positioning and activity: It is advisable that the newborn be placed prone in the isolette and even during nursing to prevent injury to the exposed neural tissue.
• Placode care: The neural placode should be covered with a wet dressing to keep it moist. The authors prefer a 4 x 4” gauze moistened with sterile normal saline and kept moist at all times. Be careful that the moistened gauze is only over the placode to prevent skin maceration. A dry 4 x 4” gauze can be placed over that or a gauze roll can be wrapped around the child to cover the placode (28). Prevention of contamination or exposure of the myelomeningocele area to soiling can be achieved with a plastic flap (steri-drape).
• IV antibiotics: Prophylactic antibiotic coverage should be started with broad-spectrum coverage (e.g., ampicillin plus gentamicin).
• Head circumference: Initial measurement of the head circumference should be obtained.