Neural tube defects and spinal dysraphism: Case

This girl has an open lumbosacral myelomeningocele with the Chiari II malformation and early hydrocephalus. The exposed neural placode with the cerebrospinal fluid leak is the classic open lesion, the lemon and banana signs on the prenatal scan are the cranial signs of the Chiari II, and the full fontanelle and the head circumference above the 97th centile point to the hydrocephalus. The motor level, around L2 to L3 given that she flexes her hips but moves nothing below the knees, predicts a significant motor deficit and a likely dependence on the wheelchair. The absent anal wink marks the sacral involvement and the neurogenic bowel and bladder. [1]

Clinical findings and assessment

The key findings are the open lumbosacral lesion with the neural placode, the motor level at L2 to L3, the absent sacral function, and the early hydrocephalus with the Chiari II. The pattern is unmistakable for a myelomeningocele, and the working diagnosis is confirmed by the prenatal scan. The motor level is the finding that frames the prognosis, because a lesion above L2 predicts a worse motor outcome and a lower chance of community ambulation, while a lesion at or below L3 would predict a better outcome. This girl's level is at the higher end, which means the ambulation potential is guarded. [1]

The differential of a newborn with a midline back lesion includes the meningocele, where the sac contains only cerebrospinal fluid and the cord is spared, and the occult dysraphic states, where the skin is intact. This girl's lesion has the neural placode exposed, so it is a myelomeningocele and not a meningocele, and the near-universal Chiari II and hydrocephalus belong to this phenotype. The meningocele carries a better prognosis because the cord and the roots are spared, but this girl's motor deficit confirms the neural tissue involvement. [7]

Immediate management

The immediate management is the latex-free protection and the neurosurgical closure. I would keep the girl in a latex-free environment from the first contact, because the latex sensitisation that complicates spina bifida begins with the early and the repeated exposure, and the latex anaphylaxis under anaesthesia is the feared complication. I would place her prone or lateral and cover the lesion with a sterile saline-soaked dressing that is changed regularly to keep the placode moist and clean. I would start the broad-spectrum antibiotics that cover the skin flora, such as a first-generation cephalosporin. [10]

I would call the neurosurgical team at the outset for the closure within 24 to 72 hours. The closure is the definitive treatment, and the early timing prevents the infection and preserves the remaining neurological function. The surgeon frees the neural placode from the surrounding tissue, reconstructs the neural tube, closes the meninges, and brings the muscle and the skin over the defect. The closure is the first operation of a lifelong neurosurgical journey, because the hydrocephalus, the Chiari II, and the later tethering will each need the neurosurgical attention. [1]

Hydrocephalus and the Chiari II malformation

The hydrocephalus complicates 80 to 90 percent of myelomeningoceles, and this girl's full fontanelle and head circumference above the 97th centile confirm it. The cranial ultrasound or the magnetic resonance imaging would show the downward herniation of the cerebellar vermis and the brainstem through the foramen magnum, the Chiari II malformation, and the ventriculomegaly of the obstructive hydrocephalus. The shunt, a ventriculoperitoneal shunt, is placed when the ventriculomegaly progresses, either at the time of the lesion closure or soon after, and it becomes a central feature of the girl's life. [7]

The Chiari II malformation is managed expectantly when it is asymptomatic, but the girl would be watched for the stridor, the swallowing difficulty, the apnoea, and the arm weakness that are the signs of the brainstem compression. These signs would need the urgent posterior fossa decompression, once the shunt malfunction is excluded, because a shunt that does not drain produces the same brainstem signs through the rising intracranial pressure. The family would be taught the shunt malfunction signs, which are the headache, the vomiting, the drowsiness, and the change in the eyes or the conscious level, and the Chiari II signs, as part of the discharge safety-net. [7]

Neurogenic bladder and bowel

The absent anal wink and the motor level at L2 to L3 mark the neurogenic bowel and bladder, and the management is started early to protect the kidneys. The renal ultrasound and the urodynamic studies would assess the bladder compliance and the upper tract dilation, because the high storage pressure and the vesicoureteric reflux threaten the kidneys. The clean intermittent catheterisation is the foundation, started early to ensure the complete bladder emptying and the low storage pressure, and the anticholinergic drugs, such as the oxybutynin, are added to relax the detrusor and to increase the bladder capacity. [9]

The EAU and ESPU guidelines set out the standard, and the bladder management is driven by the urodynamics and the renal ultrasound, not by the symptoms, because the high storage pressure damages the kidneys before the incontinence appears. The upper tract surveillance with the regular renal ultrasound is the safeguard, and the bladder management is intensified when the upper tract dilation appears. The social continence is a later goal, and the renal protection is the earlier and the more important one, because the renal failure from the unmanaged neurogenic bladder is the long-term complication that shortens the life. [9]

Outcome and family counselling

The prognosis for the survival is good with the modern management, and most children with the myelomeningocele survive into adulthood. The prognosis for the ambulation tracks the motor level, and this girl's level at L2 to L3 predicts a guarded ambulation potential, and she is likely to need the orthoses and possibly the wheelchair for the community mobility. The prognosis for the continence tracks the urological management, and the clean intermittent catheterisation achieves the social continence in most children. The cognitive outcome is shaped by the shunt complications, and most children have an intelligence in the normal range, though the learning and the behavioural difficulties are common. [1]

I would counsel the family honestly at every stage. I would explain that their daughter has a gap in the spine where the nerves did not close over in the early weeks, that the team will close the gap in the first few days of life to protect the nerves, and that she may need a tube called a shunt to drain the fluid from the brain. I would name the bladder care, the clean intermittent catheterisation, as the way the team keeps the kidneys safe and the girl dry, and the latex-free environment as the way the team prevents the allergy. I would reassure them that most children survive into adulthood and that the walking and the continence depend on the level of the gap and the care they receive. Before discharge I would give the family the written safety-net with the shunt and the Chiari II signs, and the direct line to the neurosurgical service, and I would start the lifelong multidisciplinary follow-up across neurosurgery, urology, orthopaedics, and rehabilitation. [1][9]

For the next pregnancy, I would prescribe the 4 milligram folic acid, because this mother has a child with a myelomeningocele and the recurrence risk is 3 to 5 percent. The supplement is started at least one month before the conception and continued through the first trimester, taken separately from the routine multivitamin. The Medical Research Council Vitamin Study showed the 4 milligram dose reduced the recurrence by about 72 percent, and the United States Preventive Services Task Force reaffirmed the recommendation. The prenatal screening for the next pregnancy would include the maternal serum alpha-fetoprotein and the detailed fetal ultrasound. [3][5]