Chapter 72 Spina Bifida
PATHOPHYSIOLOGY
Spina bifida means cleft spine, which is the incomplete closure of the spinal column. Two distinct types of failure of fusion of the vertebral laminae of the spinal column occur during fetal development: spina bifida occulta and spina bifida cystica.
Spina bifida occulta is a defect in closure in which the meninges are not exposed on the surface of the skin. The vertebral defect is small, usually involving the lumbosacral region. External abnormalities (present in 50% of cases) may include a hair tuft, nevus, or hemangioma. A pilonidal sinus may require surgical closure if it becomes infected.
Spina bifida cystica is a defect in closure that results in protrusion of the spinal cord and/or its coverings. The two types of spina bifida cystica are meningocele and myelomeningocele.
Meningocele is a protrusion that includes the meninges and a sac containing cerebrospinal fluid (CSF); it is covered by normal skin. No neurologic abnormalities are present, and the spinal cord is not involved. Hydrocephalus occurs in 20% of cases. A meningocele usually is in the lumbosacral or the sacral area. Surgical correction is usually performed within days of birth.
Myelomeningocele is a protrusion of the meninges and a portion of the spinal cord, as well as a sac containing CSF. The site is most often the lumbar or the lumbosacral area. The lumbosacral area is affected in 42% of cases, the thoracolumbar area in 27%, the sacral area in 21%, and the thoracic or cervical in 10%. Infants with a myelomeningocele are prone to injury during the birth process. Hydrocephalus occurs in most affected children (85% to 90%); about 60% to 70% have a normal intelligence quotient, but impairments of conceptual reasoning abilities are common. Children with both myelomeningocele and hydrocephalus have other central nervous system malformations, of which Arnold-Chiari deformity is the most common. Surgical intervention usually is performed at birth, with neurosurgery for shunt placement to prevent hydrocephalus if indicated. More recently, experimental fetal surgical procedures (done about 7 weeks before birth) have demonstrated the potential to reduce the symptoms of spina bifida.
The specific cause of spina bifida is unknown. Multiple factors such as heredity and environment are thought to interact to produce these defects. The neural tube is normally complete 4 weeks after conception. The following have been identified as causative factors: low levels of maternal vitamins, including folic acid; the taking of clomiphene and valproic acid; and hyperthermia during pregnancy. It is estimated that nearly 75% of neural tube defects could be prevented if women took vitamins, including folic acid, before conception. Widespread public health efforts are now directed to encouraging women to take daily folic acid supplements (400 mcg daily) for 1 to 3 months before becoming pregnant.
Advances in interdisciplinary care have improved the long-term outcome for affected children. Treatment improvement, with the use of medications and neurosurgery, has contributed to extending their life spans.
Diminished self-esteem is common in children and adolescents with this condition. Adolescents express concerns about sexual adequacy, social mastery, peer relationships, and physical maturity and attractiveness. The perceived severity of disability is more directly related to self-perception of the disability than to the actual disability of the adolescent.
INCIDENCE
1. Annually, approximately 4000 infants are born with spina bifida in the United States.
2. In the United States, the incidence is 1 in 1000 live births.
3. The risk of the disorder increases by 5% with the second child.
4. Girls are more often affected than boys.
5. Nearly 72% of children with spina bifida have latex or natural rubber allergies.
6. Between 80% and 90% of individuals with myelomeningocele have shunts.
CLINICAL MANIFESTATIONS
A varying degree of dysfunction affecting the skeleton, the skin, and the genitourinary tract results from spina bifida, depending on the portion of the spinal cord involved:
COMPLICATIONS
Birth-related complications of spina bifida include the following:
Other long-term complications include the following:
1. Infectious and inflammatory: shunt infections, ventriculitis, meningitis, tendonitis, decubitus ulcer
2. Neurologic and neurosensory: increased intracranial pressure due to blocked shunt, blocked shunt (may be asymptomatic), tethered cord syndrome, benign intracranial hypertension, slit ventricle syndrome, visual deficits
3. Immune: latex sensitization and allergy
4. Gastrointestinal: bowel problems (incontinence), gastrointestinal disorders
5. Endocrine: obesity, impaired sexual and reproductive functioning
6. Integumentary: decubitus ulcer, traumatic injury to insensate areas
7. Orthopedic problems: foot deformities, bowed legs, dislocated hips, spinal curvature, osteoporosis, mobility limitations
8. Cognitive: learning disabilities
9. Psychologic: depression, anxiety disorders, low self-esteem, altered body image
LABORATORY AND DIAGNOSTIC TESTS
1. Antenatal period testing: serum alpha fetoprotein level between 16 and 18 weeks of gestation, ultrasonography of fetus, amniocentesis if other tests are inconclusive
2. Diagnostic examinations: chest radiographic study, ultrasonography, computed tomography, magnetic resonance imaging, amniocentesis
3. Routine preoperative testing: complete blood count, urinalysis, culture and sensitivity (C and S) testing, chest radiographic study
MEDICAL AND SURGICAL MANAGEMENT
Surgical repair of myelomeningocele is performed in the neonatal period to prevent rupture. Surgical repair of the spinal lesion and shunting of CSF in infants with hydrocephalus is performed at birth. Skin grafting is necessary if the lesion is large. Children with spina bifida are at risk for latex sensitization and allergy because they are exposed to surgeries and procedures in which latex gloves come into direct contact with blood vessels and mucosa. Risk factors associated with the development of latex sensitization and allergy are atopic diathesis and number of surgeries. Children who have latex allergy have clinical symptoms, whereas those with latex sensitization have immunoglobulin E antibodies with no clinical symptoms. Whether the child has latex allergy or sensitization, avoidance of contact with latex is recommended.
Prophylactic antibiotics are administered to prevent infection. Nursing interventions will depend on the presence and extent of dysfunction of various body systems. In addition, children with myelomeningocele will undergo a number of surgeries depending on their clinical problems, such as tethered spinal cord, orthopedic problems, decubitus ulcers, and a shunt that requires revision.
The following medications may be used depending on the child’s clinical needs:
1. Antibiotics and/or antiseptics—used prophylactically to prevent urinary tract infections
2. Anticholinergics—to increase bladder tone
3. Alpha agonists—to tighten sphincter
4. Stool softeners and laxatives—used for bowel training and evacuation of stool
5. Medications—to control or treat other medical and mental health problems such as epilepsy, depression
