Neurologic deficits — The specific neurologic deficits depend upon the level of the lesion. In most affected patients, the entire spinal cord distal to the site of the lesion is nonfunctional. Motor and sensory deficits in the trunk and legs correspond to the segments that normally would have been innervated. The deficits usually are severe, resulting in complete paralysis and absence of sensation. The bladder and bowel are affected in nearly all patients, resulting in urinary and fecal incontinence.

Occasionally, the distal cord may retain some function, but the afferent pathways to the brain are disrupted. In this case, tendon reflexes or withdrawal to pain may be preserved, although voluntary control of movement and appreciation of pain are absent. A partially functioning segment of the spinal cord sometimes retains some central connections, resulting in voluntary control of isolated movements or the appreciation of sensation in part of the involved limbs. Aberrant connections in the involved spinal cord may result in unusual findings such as contraction of the contralateral limb when tendon reflexes are elicited.

Hydrocephalus — The majority of patients with myelomeningocele have hydrocephalus. The etiology is obstruction of fourth ventricular outflow or flow of CSF through the posterior fossa due to Chiari malformation or an associated aqueductal stenosis [23]. In one series of 156 children with myelomeningocele, 80 percent developed this disorder [24]. Hydrocephalus was due to aqueductal stenosis in 73 percent. Signs of hydrocephalus were present at birth in 15 percent of cases.

The likelihood of hydrocephalus depends upon the site of the lesion. Hydrocephalus is associated with approximately 90 percent of thoracolumbar, lumbar, and lumbosacral lesions, and approximately 60 percent of occipital, cervical, thoracic, or sacral lesions [22].

Ventricular dilatation is common at birth, often without increased head circumference or signs of increased intracranial pressure [25]. Hydrocephalus typically develops in the neonatal period after surgical repair of the back lesion. This is due to accumulation of excess CSF that previously was decompressed into the large sac or through a leaking myelomeningocele. Shunting is required in most patients.

Chiari malformation — The Chiari malformation is an anomaly of the hindbrain present in nearly all patients with thoracolumbar, lumbar, and lumbosacral myelomeningocele. It is the primary cause of the associated hydrocephalus. The major features of the anomaly are [22]:

Inferior displacement of the medulla and fourth ventricle into the upper cervical canal
Elongation and thinning of the upper medulla and lower pons and persistence of the embryonic flexure of these structures
Inferior displacement of the lower cerebellum through the foramen magnum in the upper cervical region
Bony defects of the foramen magnum, occiput, and upper cervical vertebrae
The malformation is classified into three types, according to the degree of caudal displacement. Type II, in which the fourth ventricle and lower medulla are displaced below the level of the foramen magnum, is the form that is usually associated with myelomeningocele.

Brain stem dysfunction due to the Chiari malformation occurs in some patients with myelomeningocele. This results in problems such as swallowing difficulties, vocal cord paresis causing stridor, and apneic episodes, and is associated with a high mortality rate [22]. Strabismus and facial weakness can also occur.

Other CNS anomalies — Other CNS anomalies often accompany myelomeningocele. In one report, neuropathologic examination was performed on 25 children with myelomeningocele, Chiari malformation, and hydrocephalus [26]. Cerebral cortical dysplasia occurred in 92 percent. The majority had neuronal heterotopias or polymicrogyria. Other abnormalities noted included cerebellar dysplasia (72 percent), hypoplasia or aplasia of cranial nerve nuclei (20 percent), fusion of the thalami (16 percent), agenesis of the corpus callosum (12 percent), and complete or partial agenesis of the olfactory tract and bulb (8 percent).

Scoliosis — Scoliosis occurs in most children with meningomyelocele who have lesions above L2 [22]. This complication is unusual when the lesion is below S1.

MANAGEMENT — Management of children with spina bifida should involve a multidisciplinary team with expertise in developmental pediatrics, neurosurgery, orthopedics, neurology, urology, and physical medicine and rehabilitation. Physical and occupational therapists, nutritionists, social workers, wound specialists, and psychologists are also helpful. This team of specialists works together to coordinate care and evaluate the patient's progress.

Delivery — If a prenatal diagnosis of myelomeningocele has been made, delivery should occur at a hospital with personnel experienced in the neonatal management of these infants [27]. Delivery before term may be indicated if rapidly increasing ventriculomegaly is observed and fetal lung maturity has been documented, otherwise, term delivery is preferable [27]. Sterile nonlatex gloves should be used during delivery to minimize the risk of latex sensitization [28].

Breech presenting fetuses are typically delivered by cesarean section. (See "Delivery of the fetus in breech presentation"). The optimal route of delivery of the vertex fetus is controversial, and no prospective randomized trials have been performed.

One study compared the outcome of 47 infants with a prenatal diagnosis of isolated myelomeningocele without severe hydrocephalus delivered by cesarean section before labor to a historic cohort of 113 infants with myelomeningocele diagnosed after delivery (35 delivered by cesarean section after a period of labor and 78 delivered vaginally) [29]. The level of paralysis at two years of age was approximately two segments lower in the group delivered by elective cesarean section without labor. However, it is possible that advances in neonatal care and prenatal diagnosis led to interventions in the delivery room that resulted in a better outcome in the study group. Several other retrospective studies, but not all [30], have not found a benefit of cesarean delivery, with or without labor, compared to vaginal birth [31-36].

Most centers deliver these infants by cesarean birth. Since data are inadequate to make a general recommendation about the optimal route of delivery, this decision should be individualized [27]. Future trials should address the effects of both route of delivery and labor on neuromuscular function.

Neonatal assessment — Immediately after birth, the lesion should be briefly assessed to note its location, size, and whether it is leaking CSF. Sterile non-latex gloves should be used. The defect should be covered with a sterile saline-soaked dressing. Large defects should also be covered by plastic wrap to prevent heat loss. In most cases, only the neurosurgeon should remove the dressing. The infant should be placed in a prone or lateral position to avoid pressure on the lesion.

The newborn should be evaluated thoroughly to detect associated abnormalities in order to make appropriate decisions regarding treatment [37]. The parents should be counseled regarding the infant's prognosis and participate in decisions regarding management [38].