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Spina
bifida is defective closure of the vertebral column. Although the
cause is not known, low folate levels during pregnancy increase
risk. Some cases are asymptomatic, and others cause severe
neurologic dysfunction below the lesion. Open spina bifida can be
diagnosed prenatally by ultrasound or suggested by elevated α-fetoprotein levels in maternal
serum and amniotic fluid. After birth, a lesion is typically visible
on the back. Treatment is usually surgical.
Spina bifida is one of the most serious neural tube defects compatible with prolonged life. It is most common in the lower thoracic, lumbar, or sacral region and usually extends for 3 to 6 vertebral segments. Severity ranges from occult, in which there are no apparent anomalies, to protruding sacs (spina bifida cystica), to a completely open spine (rachischisis) with severe neurologic disability and death.
In occult spina bifida, anomalies of the skin overlying the lower back (typically in the lumbosacral area) occur; these include sinus tracts that have no visible bottom, are above the lower sacral area, or are not in the midline; hyperpigmented areas; and tufts of hair. These children often have anomalies in the underlying portion of the spinal cord, such as lipomas and tethering (in which the cord has an abnormal attachment).
In spina bifida cystica, the protruding sac can contain meninges (meningocele), spinal cord (myelocele), or both (meningomyelocele). In a meningomyelocele, the sac usually consists of meninges with a central neural plaque. If not well covered with skin, the sac can easily rupture, increasing the risk of meningitis.
Hydrocephalus is common and may be related to Chiari II type malformations (see Congenital Neurologic Anomalies: Hydrocephalus) or aqueductal stenosis. Other congenital anomalies, such as abnormal migration of neuronal cells in the brain, syringomyelia, and soft-tissue masses, may be present.
Symptoms and Signs
Many children with minor defects are asymptomatic. When the spinal cord or lumbosacral nerve roots are involved, as is usual, varying degrees of paralysis affect all muscles below the lesion. Lack of muscle innervation also leads to atrophy of the legs and decreased rectal tone. Because paralysis occurs in the fetus, orthopedic problems may be present at birth (eg, clubfoot, arthrogryposis of the legs, dislocated hip). Kyphosis is sometimes present and can hinder surgical closure and prevent the patient from lying supine.
Paralysis also impairs bladder function, leading to urine reflux, which can cause hydronephrosis, frequent UTIs, and, ultimately, kidney damage.
Diagnosis
Spinal cord imaging, with ultrasonography or MRI, is essential; even children with minimal cutaneous findings may have underlying spinal abnormalities. Plain x-rays of the spine, hips, and, if they are malformed, lower extremities are obtained along with cranial imaging by using ultrasonography, CT, or MRI.
Once the diagnosis of spina bifida is made, urinary tract evaluation is essential and includes urinalysis, urine culture, BUN and creatinine determination, and ultrasonography. Measurement of the bladder capacity and pressure at which urine refluxes into the urethra can determine prognosis and intervention. Need for further testing, such as urodynamics and voiding cystourethrogram, depends on previous findings and associated anomalies.
Prognosis
Prognosis varies by the level of cord involvement and the number and severity of associated anomalies. Prognosis is poorest for patients with higher cord levels (eg, thoracic) or who have kyphosis, hydrocephalus, early hydronephrosis, and associated congenital anomalies. With proper care, however, many children do well. Loss of renal function and shunt complications are the usual causes of death in older patients.
Treatment
and Prevention
Without rapid surgical treatment, neurologic damage can progress. Treatment requires a united effort by specialists from several disciplines; neurosurgical, urologic, orthopedic, pediatric, and social service evaluations are initially important. It is important to assess the type, vertebral segment, and extent of the lesion; the infant's health status; and associated anomalies. Prior to intervention, discussion with the family should ascertain the family's strengths, desires, and resources, and community resources, including availability of ongoing care.
A meningomyelocele identified at birth is covered immediately with a sterile dressing. If the meningomyelocele is leaking CSF, antibiotics are started to prevent meningitis. Neurosurgical repair of a meningomyelocele or an open spine typically is performed within the 1st 72 h after birth to reduce the risk of meningeal or ventricular infection. If the lesion is large or is in a difficult location, plastic surgeons may be consulted to ensure adequate closure.
Hydrocephalus may require a shunt procedure in the neonatal period. Kidney function must be followed closely, and UTI should be treated promptly. Obstructive uropathy at either the bladder outlet or ureteral level must be treated vigorously to prevent infection. Orthopedic care should begin early. If a clubfoot is present, a cast is applied. Hip joints are checked for dislocation. Affected children should be monitored for development of scoliosis, pathologic fractures, pressure sores, and muscle weakness and spasm.
Folate supplementation in women beginning 3 mo before conception and during the 1st trimester reduces the risk for neural tube defects (see Congenital Neurologic Anomalies).
Last full review/revision November 2005
Content last modified November 2005
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