AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Myelomeningocele is a complex congenital spinal anomaly that causes varying degrees of spinal cord malformation, or myelodysplasia. It is commonly referred to as spina bifida and is classified as a defect of the neural tube (ie, the embryonic structure that develops into the spinal cord and brain). Patients with myelomeningocele present with a spectrum of impairments, but the primary functional deficits are lower limb paralysis and sensory loss, bladder and bowel dysfunction, and cognitive dysfunction. Medical, surgical, and rehabilitation issues arise in the patient with myelomeningocele from birth through adulthood.

Pathophysiology

Neural tube defects are the result of a teratogenic process that causes failed closure and abnormal differentiation of the embryonic neural tube during the first 4 weeks of gestation. The most common neural tube defects are anencephaly and myelomeningocele. Anencephaly results from failed closure of the rostral end of the neural tube, resulting in incomplete formation of the brain and skull. Myelomeningocele results from failed closure of the caudal end of the neural tube, resulting in an open lesion or sac that contains dysplastic spinal cord, nerve roots, meninges, vertebral bodies, and skin. The anatomic level of the myelomeningocele sac roughly correlates with the patient's neurologic, motor, and sensory deficits.

Myelomeningocele is associated with abnormal development of the cranial neural tube, which results in several characteristic CNS anomalies. The Chiari type II malformation is characterized by cerebellar hypoplasia and varying degrees of caudal displacement of the lower brainstem into the upper cervical canal through the foramen magnum. This deformity impedes the flow and absorption of cerebrospinal fluid (CSF) and causes hydrocephalus, which occurs in more than 90% of infants with myelomeningocele. Cerebral cortex dysplasia, including heterotopias, polymicrogyria, abnormal lamination, fused thalami, and corpus callosum abnormalities, also occurs frequently. Mesodermal structures surrounding the neural tube, such as the vertebra and ribs, also may be malformed.

Myelomeningocele often occurs with multiple system congenital anomalies. Commonly associated anomalies are facial clefts, heart malformations, and genitourinary tract anomalies. Urinary tract anomalies, such as solitary kidney or malformed ureters, may contribute to increased morbidity in the presence of neurogenic bladder dysfunction.

Frequency

United States

Neural tube defects are the second most common type of birth defect after congenital heart defects, and myelomeningocele is the most common form of neural tube defect. In the United States, approximately 1500 infants are born with myelomeningocele each year. Birth incidence of the disease was reported to be 4.4-4.6 cases per 10,000 live births from 1983-1990. Rates varied by region, with the highest rates occurring in Appalachia. The rate of myelomeningocele and other neural tube defects has declined over the last 3 decades. This is attributed to the widespread availability of prenatal diagnostic services and to improved nutrition among pregnant women.

International

The rates of myelomeningocele vary widely among countries and by geographic regions within countries. Neural tube defects occur at frequencies (per 10,000 births) ranging from 0.9 in Canada and 0.7 in central France, to 7.7 in the United Arab Emirates and 11.7 in South America. Low socioeconomic status is associated with higher risk in many populations. In the last 50 years, epidemics of myelomeningocele have occurred in Boston, Mass; Rochester, NY; Dublin, Ireland; The People's Republic of China; and Jamaica.

Mortality/Morbidity

In the United States, the leading identified cause of infant death is birth defects, and myelomeningocele is one of the most common birth defects. In general, survival and degree of neurologic impairment depend on the level of the spinal segment involved, the severity of the lesion, and the extent of associated abnormalities.

The mortality rate for infants with myelomeningocele is increased over the general population risk in the first year of the life. Mortality rates reported for untreated infants range from 90-100% based on several studies dating from the turn of the century through recent years. Most untreated infants die within the first year of life. Death in the first 2 years of life for those untreated usually results from hydrocephalus or intracranial infection. The likelihood that a 2-month-old infant untreated for myelomeningocele lives 7 years is only 28%.

Survival rates for infants born with myelomeningocele have improved dramatically with the introduction of antibiotics and developments in the neurosurgical treatment of hydrocephalus. Early death in both treated and untreated patients is associated with advanced hydrocephalus and multiple system congenital anomalies. In the United States, antibiotics, sac closure, and ventriculoperitoneal shunt placement are the standard of care and are implemented in the perinatal period in 93-95% of patients. Supportive care only may be recommended in cases associated with an irreparable sac, active gross CNS infection or bleeding, and/or other gross congenital organ anomalies causing life-threatening problems.

Paraplegia from the myelodysplasia typically causes some impairment of motor and sensory function below the level of the lesion, along with neurogenic bowel and bladder and sexual dysfunction. Musculoskeletal complications may be caused by progressive bony and joint deformities, pathologic fractures, and muscle deterioration.

Many other neurologic problems may manifest acutely or chronically at birth or later, resulting in global cognitive and/or specific motor impairments. These neurologic complications are related to a number of distinct cerebral and intraspinal pathologies. Cognitive dysfunction is most strongly correlated with the presence of hydrocephalus, along with hydrocephalus-related illness parameters (ie, the necessity of shunting, number of shunt revisions, shunt infections, and additional structural abnormalities of the CNS). Cognitive function has also been related to the level of the lesion. Upper-level lesions have been associated with a higher frequency of mental retardation and lower scores on measures of intelligence, academic skills, and adaptive behavior.

Renal compromise occurs because of problems related to neurogenic bladder. Despite advances in the management of neurogenic bladder, renal failure is still the leading cause of death in patients with myelomeningocele after the first year of life.

Race

Epidemiologic studies have shown that the prevalence of myelomeningocele varies across time, by region, and by both race and ethnicity. In the United States, data from state and national surveillance systems from 1983-1990 showed rates highest for Hispanics and whites and lowest for Asians. The rates are 0.15% in the white population and 0.04% in the black population; a higher proportion of whites than blacks have thoracic-level malformations.

Sex

The birth prevalence rate of myelomeningocele was slightly higher in females than in males (1.2:1), based on data from both state and national surveillance systems from 1983-1990. A higher proportion of females than males exhibit thoracic-level malformations.

Age

Myelomeningocele is a common congential anomaly and therefore is present at birth.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Myelomeningocele is diagnosed at birth or in utero. At birth, a midline defect in the posterior elements of the vertebrae is noted with protrusion of the meninges and neural elements through an external dural sac.

Physical

• The most obvious finding on physical examination is some degree of motor and sensory loss.
  • Neurologic impairment is classified by traditional neurosegmental levels based on the clinically determined strength of specific muscle groups. The functional motor level does not always correspond to the anatomic level of the lesion. In addition, it is important to realize that the motor paresis may be asymmetrical, that it may not correspond to the sensory level, and that it may be combination of upper and lower motor neuron lesions.Serial measurements and accurate documentation of the functional level of the lesion allow for early detection of progressive neurologic deterioration related to a variety of associated CNS problems.
  • In addition to determining the functional neurosegmental level, it is important to distinguish the type of paralysis, either spastic or flaccid. Most patients with myelomeningocele have a flaccid paraparesis below the spinal cord lesion. An estimated 10-25% of patients have been reported to have a spastic paraparesis. This presentation is presumed to be related to an intact but isolated segment of cord distal to the lesion. Spastic paraparesis has been associated with a poorer prognosis for walking and higher rates of orthopedic procedures.
• Myelomeningocele patients frequently are described as belonging to certain groups, based on the neurosegmental level of the lesion. This approach is useful for general functional prognosis and anticipation of specific musculoskeletal complications.
  • In the thoracic group, innervation of the upper limb and neck musculature and variable function of trunk musculature are present with no volitional lower limb movements. Patients with thoracic malformations tend to have more involvement of the CNS and associated cognitive deficits.
  • In the high-lumbar group, variable hip flexor and hip adductor strength is characteristic, and absence of hip extensors, hip abductors, and all knee and ankle movements are noted.
  • In the low-lumbar group, hip flexor, adductor, medial hamstring, and quadriceps strength is present; strength of the lateral hamstrings, hip abductors, and ankle dorsiflexors is variable; and strength of the ankle plantar flexors is absent.
  • In the sacral-level group, strength of all hip and knee groups is present, and ankle plantar flexor strength is variable.
• Involvement of the upper extremities is also common. Spasticity in the upper extremities occurs in approximately 20% of patients with myelomeningocele. It has been related to the number of shunts required to control hydrocephalus and has been shown to adversely affect independence in activities of daily living. In patients with hydrocephalus, lack of upper extremity coordination is also seen. This lack of coordination also may be related to Chiari II malformation, motor-learning deficits, and/or delayed development of hand dominance. Affected children have problems with fine motor tasks, particularly when timed. New-onset weakness or spasticity in the upper extremities may be a hallmark of progressive neurologic dysfunction.
• Spinal and lower extremity deformities and joint contractures are prevalent in children with myelomeningocele. Multiple factors may be involved, including intrauterine positioning, other congenital malformations, muscle imbalances, progressive neurologic dysfunction, poor postural habits, and reduced or absent joint motion.
• • Spinal deformities may be congenital or acquired. Vertebrae and rib anomalies are associated with congential or early development of severe kyphotic and scoliotic deformities. Acquired scoliosis is neuromuscular in origin and is related to muscle imbalances. Increased lumbar lordosis and kyphosis of the entire spine or localized to the lumbar region are also observed. All of the spinal deformities occur more frequently in groups with higher spinal lesions.
  • The lower extremity deformities that occur are related to the functional level of the lesion. Thoracic and high-lumbar groups tend to have increased prevalences of lumbar lordosis, hip abduction and external rotation contractures, knee flexion, and equinus contractures of the ankles. Unopposed hip flexion and adduction contractures in the high-lumbar group frequently result in dislocated hips. The mid- and low-lumbar groups often have hip and knee flexion contractures, increased lumbar lordosis, genu valgus and calcaneal valgus malalignment, and overpronated feet. Patients in the sacral group often exhibit mild hip and knee flexion contractures and increased lumbar lordosis with various ankle and foot positions.
• Children with myelomeningocele are often short in stature. This has been related to multiple factors, including (1) structural issues such as abnormalities of the spinal column and lower limb contractures; (2) functional spinal level, which influences the amount of neurotrophic input from the lower extremities on appendicular skeletal growth; and (3) alteration in the hypothalamic-pituitary axis, likely related to hydrocephalus.
• Ocular muscle palsies, swallowing and eating problems, and abnormal phonation are signs of cranial nerve dysfunction. These symptoms may be related to the Chiari II malformation, hydrocephalus, and/or brainstem dysplasia.

Causes

The etiology in most cases of myelomeningocele is multifactorial, involving genetic, racial, and environmental factors.

• Other offspring in a family with one affected child are at increased risk of neural tube defect than children without affected siblings.
• • The risk is 1 in 20-30 for subsequent pregnancies, and if 2 children are affected, the risk becomes 1 in 2. An increase in the risk of myelomeningocele has also been reported for second- and third-degree relatives of affected individuals.
  • Most infants born with myelomeningocele are born to mothers with no previously affected children.
• A small number of cases are linked to specific etiologic factors.
• • Up to 10% of fetuses with a neural tube defect detected in early gestation have an associated chromosome abnormality.
  • Associated chromosome abnormalities include trisomies 13 and 18, triploidy, and single gene mutations.
  • In women with pregestational diabetes, the risk of having a child with a CNS malformation, including myelomeningocele, is 2-10 fold higher than the risk in the general population. The mechanism underlying this teratogenic effect is not well defined but is related to the degree of maternal metabolic control. The risk of women who develop gestational diabetes is lower than the risk of women with pregestational diabetes, but it might not be as low as in the general population.
  • Other risk factors for myelomeningocele include maternal obesity, hyperthermia (as the result of maternal fever or febrile illness or associated with the use of saunas, hot tubs, and tanning beds), and maternal diarrhea.
  • Intrauterine drug exposures to valproate, carbamazepine, and drugs to induce ovulation are identified risk factors.
  • The risk of having a child with myelomeningocele has also been associated with maternal exposures to fumonisins, electromagnetic fields, hazardous waste sites, disinfection by-products found in drinking water, and pesticides.
• Research in the 1980s showed correction of folic acid deficiency as an effective means of primary and recurrent prevention.
• • After 1991, 50% of cases of neural tube defects are related to a nutritional deficiency of folic acid and, thus, are preventable.
  • In September 1992, the US Public Health Service (USPHS) recommended intake of folic acid at a dosage of 0.4 mg/d for all women anticipating pregnancy.
  • In February 1996, the USPHS announced mandatory folic acid fortification of enriched cereal grain, a measure expected to increase the daily intake of folic acid in women of reproductive age by approximately 100 mcg/d.
  • After fortification, an estimated 24% decline in myelomeningocele rates was reported in 2001 compared to 1996, based on data from United States surveillance systems.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Meningocele is the herniated protrusion of only the meninges through a defect in the cranium or vertebral column. This lesion does not contain neural tissue in the sac.

Spina bifida occulta is a common radiographic finding characterized by simple lack of fusion of vertebral spinous processes.

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Laboratory screening tests for neural tube defects can be performed through 2 methods, blood tests and/or amniocentesis, typically used in combination with fetal ultrasonography.
• • Estimation of maternal serum alpha-fetoprotein (AFP) has been used since the late 1970s. Blood samples are taken early in the second trimester, and, if the fetus has an open spina bifida, the AFP level is elevated in 70-75% of cases.
  • Since many possible reasons exist for false positive results, a presumptive diagnosis made based on maternal serum AFP is confirmed with amniocentesis and assay of the amniotic fluid for AFP, as well as for the presence of acetylcholinesterase, a nerve-specific enzyme.
  • Myelomeningocele can be detected in 99% of affected fetuses through combined use of these tests.
• Perform urinalysis, urine culture, and serum urea nitrogen creatinine test at birth to evaluate renal function. Recommend regular bacterial urinary cultures for children who have vesicoureteral reflux or signs and symptoms of urinary tract infection.

Imaging Studies

• Fetal ultrasound
• • Some centers use fetal ultrasound as the primary screening tool for neural tube defects, usually at approximately 18 weeks gestational age. This trend reflects the increasing sophistication of fetal ultrasonographic technology. The procedure avoids the roughly 1% risk of abortion following amniocentesis, but accurate diagnosis depends on the skill and experience of the operator and the quality of the equipment.
  • Combining the use of maternal serum AFP screening with second-trimester ultrasound screening, over 90% of neural tube defects are detected from 20 weeks' gestation.
• With ultrasonography, myelomeningocele may be detected during scanning of the fetal head for subtle changes in the cranial and cerebellar configurations. The diagnosis of myelomeningocele is certain when 3 classic central findings are present: concavity of the frontal bones, ventriculomegaly, and the Chiari II malformation. Currently, ultrasonography is not sensitive enough to provide reliable and accurate detection of the level of the defect. Preliminary experience indicates that the use of 3- and 4-dimensional ultrasound will improve the accuracy in determining the upper level of the myelomeningocele lesion.
• After confirmation of fetal myelomeningocele, clinicians at most tertiary care centers perform weekly ultrasonographic examinations to observe the growth and development of the fetus.
• Neuro-imaging techniques help to monitor neurologic complications.
• • Hydrocephalus can be tracked with serial cranial ultrasounds (in infants) or CT scans.
  • MRI of the spine and brain is helpful in neurologic assessment and provides a baseline for comparison in future investigations, especially in the context of progressive neurologic deterioration.
• Radiographs
• • Radiographs of the vertebrae provide information for early evaluation when an infant is born with myelomeningocele. After delivery, the criterion standard for determining the level of the lesion is a plain film radiograph.
  • Congenital spinal deformities need to be tracked closely. Acquired or neuromuscular spinal deformities require imaging based on clinical exam; these deformities should be followed routinely during growth, and more frequently during times of rapid growth.
• Cystogram
• • Early accurate assessment and subsequent frequent reassessments of neurologic status are necessary with both anatomic and physiologic evaluation techniques.
  • Obtain the anatomic information with a voiding cystogram that assesses the lower urinary tract, including bladder capacity and the presence of vesicoureteral reflux.

Other Tests

• Urodynamics help in physiologic evaluation of urologic function by characterizing abnormalities of detrusor control and sphincter function.
• Psychometric assessments of intelligence and cognitive function are indicated for patients with hydrocephalus and for patients who display deficits with in speech and language functions and/or cognitive or academic skills.
• Gait analysis may contribute to a better understanding of how muscle innervation, strength, and recruitment patterns affect functional mobility. It often serves as a useful preoperative diagnostic tool.

Procedures

• A cesarean delivery before rupture of the amniotic membranes and the onset of labor has been recommended to reduce injury to the myelomeningocele sac and theoretically decrease the degree of paralysis. A recent study showed no difference in long-term ambulation status in infants with myelomeningocele who underwent a trial of labor compared with elective cesarean delivery.
• Studies of open intrauterine repair of the myelomeningocele suggest that this procedure may decrease hindbrain herniation, a component of the Chiari II malformation, and also favorably affect the development of hydrocephalus. However, this procedure is associated with significant risks to both mother and fetus. In 2003, a 5-year, randomized, multicenter trial was initiated with the goal of comparing the safety and efficacy of intrauterine repair with standard postnatal repair.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Rehabilitation Program

Physical Therapy

General functional expectations have been developed for patients in each lesion-level group to help direct physical therapy goals within an appropriate developmental context from infancy through adulthood. In managing the cases of newborns with myelomeningocele, the physical therapist establishes a baseline of muscle function. As the child develops, the physical therapist monitors joint alignment, muscle imbalances, contractures, posture, and signs of progressive neurologic dysfunction. The physical therapist also provides caregivers with instruction in handling and positioning techniques and recommends orthotic positioning devices to prevent soft tissue contractures. The therapy programs should be designed to parallel the normal achievement of gross motor milestones. Provide the infant with sitting opportunities to facilitate the development of head and trunk control.

Near the end of the first year of life, provide the child with an effective means of independent mobility in conjunction with therapeutic exercises that promote trunk control and balance. For patients who are not likely to become ambulatory, place emphasis on developing proficiency in wheelchair skills. For patients who are predicted to ambulate, pregait training should begin with use of a parapodium or swivel walker. Exercise or household distance ambulation may be pursued with use of traditional long leg braces (eg, hip-knee-ankle-foot orthosis, knee-ankle-foot orthosis) or the reciprocating gait orthosis [RGO]). Teach the school-aged child community-level wheelchair mobility skills, emphasizing efficiency and safety. The physical therapist assists with assessment of the community, home, and school environments to determine whether architectural barriers exist that may interfere with the child's daily activities.

Occupational Therapy

Fine motor skills and independence with activities of daily living (ADL) often are impaired. Initiate training early to compensate for these deficits and progress along the developmental sequence as closely as possible. Upper extremity stabilization and dexterous hand use require adequate postural control of the head and trunk. In the first year of life, encourage development of these postural mechanisms or substitute passive support, if necessary, to promote eye-hand coordination and manipulatory skills. When adequate fine motor skills have been achieved, the occupational therapist provides instructions for use of adaptive equipment and alternative methods for self-care and other ADL for preschool and school-aged children.

Speech Therapy

Speech therapy may be indicated for patients with speech and/or swallowing difficulties.

Recreational Therapy

Children with myelomeningocele often experience restricted play and recreational opportunities because of limited mobility and physical limitations. This inactivity decreases the potential for normal development in all spheres and can exert a negative impact on self-esteem. For the infant and toddler with myelomeningocele, recreational therapy enhances opportunities for environmental exploration and interaction with other children. For the school-aged child, recreational therapy provides opportunities for participation in adapted sports and exercise programs, which can result in long-term interest in personal fitness and health. Recreational and physical fitness goals include socialization, weight control, and improved fitness (eg, flexibility, strength, aerobic capacity, cardiovascular fitness, coordination). Recreational therapy is helpful for promoting independence with adult living skills and often is used to assist the patient with shopping for and purchasing personal

items, useof

public transportation, and development of appropriate leisure activities.

Medical Issues/Complications

Complications of myelomeningocele can be generally classified into 4 major categories: neurologic, orthopedic, urologic, and gastrointestinal.

• Neurologic complications in patients with myelomeningocele are related to a variety of both CNS and spinal cord pathologies.
• • Approximately 25-35% or more of children with myelomeningocele are born with hydrocephalus, and an additional 60-70% of patients with myelomeningocele develop hydrocephalus after closure of the myelomeningocele lesion. Hydrocephalus can cause expansion of the ventricles and loss of cerebral cortex and is associated with an increased risk of cognitive impairment.
  • Seizures occur in 10-30% of affected children and adolescents. These seizures can be related to brain malformation, or they may be a sign of shunt malfunction or infection.
  • The Chiari type II malformation is present anatomically in almost all patients with myelomeningocele and can result in hindbrain and/or upper cervical spinal cord dysfunction. Clinical manifestations of the Chiari II malformation are more common during infancy and, overall, are seen in 20-30% of affected children. However, symptoms can develop at any age and can manifest acutely or chronically. While symptoms are often mild, lower brainstem dysfunction is the leading cause of death in infants with myelomeningocele because of associated stridor, apnea, and aspiration pneumonitis. Common symptoms of lower brainstem dysfunction in infants include abnormal cry, swallowing or feeding difficulties, and frequent vomiting or gastroesophageal reflux. Older children and adults may present with weakness or spasticity of the upper extremities, headache or neck pain, cerebellar dysfunction, oculomotor changes, and scoliosis.
  • A tethered spinal cord is caused by the tendency for the spinal cord to adhere to the meningocele repair and can prevent the normal cephalad migration of the cord during growth. A tethered cord is present anatomically in most children with myelomeningocele. However, diagnosis of tethered cord syndrome is confirmed on the basis of clinical signs and symptoms, which can include pain, sensory changes, spasticity, and progressive scoliosis. In addition, uncontrolled hydrocephalus and Chiari II malformation must be excluded as causes.
  • Symptoms similar to those of tethered cord syndrome can be caused by other intraspinal pathologies (eg, mass lesions of the cord, diastematomyelia, cord cavitation and narrowing, adhesions, dural bands). Syringomyelia is caused by uncontrolled hydrocephalus that results in entry of CSF into the central canal of the spinal cord, causing dilatation and pressure. While this is a common MRI finding in patients with myelomeningocele, this condition is only symptomatic in 2-5%. Symptoms described include progressive scoliosis, spasticity, and increasing weakness of the extremities.
• Myelomeningocele is the most common cause of neurogenic bladder dysfunction in children. The nature of the urinary tract dysfunction in myelomeningocele depends on the level and extent of the spinal cord lesion. Disruption of the neural axis between the pons and the sacral spinal cord by the myelomeningocele may cause uninhibited detrusor contractions or dyssynergia, a lack of coordination of the external bladder sphincter that causes involuntary sphincter activity during detrusor contraction. Myelomeningocele in the sacral area can produce a lower motor neuron lesion, resulting in detrusor areflexia. These abnormalities may occur singly or in combination and typically result in incontinence and impaired bladder emptying that can lead to vesicoureteral reflux and high voiding pressures. If untreated, this condition can lead to potentially more serious complications, including frequent infections, upper urinary tract deterioration, and, ultimately, renal failure.
• • The main determinant of upper urinary tract deterioration is the intravesical pressure, both in storage and voiding situations. A high incidence of vesicoureteral reflux and ureteral dilation is found in patients with myelomeningocele whose leak-point pressures were greater than 40 cm water. High pressures may result from increased outlet resistance or decreased bladder wall compliance. Increased outlet resistance may be caused by sphincter dyssynergia or fibrosis of a denervated sphincter. Decreased bladder wall compliance is associated with areflexia of the detrusor. Any of these urologic dysfunctions can occur in myelomeningocele, but manifestations may vary over time because of the changing neurologic status in some of these patients.
  • Treatment strategies are designed both to prevent deterioration of renal function and to establish infection-free social continence. These goals can be accomplished by several different methods of bladder drainage, including vesicostomy, intermittent catheterization, and placement of indwelling catheters. Long-term maintenance of low bladder pressures may require the adjunctive use of medications to reduce bladder pressures and/or decrease spastic or hypotonic sphincter function. The success rate of intermittent catheterization and/or anticholinergic medications in achieving continence is estimated to reach 70-80%.
  • When infection occurs, antibiotics are used in combination with the usual techniques of bladder management. In general, high fluid intake is recommended to assist the flow of urine, as residual urine in the bladder fosters bacterial growth and infection.
• Abnormal anal sphincter function and anorectal sensation are associated with myelomeningocele involving spinal segments S2-S4. Many individuals with myelomeningocele, therefore, do not have the sensation and control needed to defecate volitionally. The result is bowel incontinence, often with related problems of constipation and impaction. Fecal incontinence can become a serious barrier in attending school, obtaining employment, or sustaining an intimate relationship.
• • Assisted bowel programs designed to empty the bowels regularly can establish social continence and prevent constipation. Develop a regimen for bowel movements, usually on a daily or every-other-day basis. These programs typically attempt to take advantage of the gastrocolic reflex by timing the bowel movement after a meal, typically breakfast or dinner. Some patients are able to use the Valsalva maneuver to defecate, but some may need the assistance of digital stimulation, a stimulant suppository, and/or an expansion enema. Use of these techniques can help to achieve proper timing of the bowel movement and complete evacuation. A high-fiber diet, sometimes in combination with use of stool softeners, may help to optimize stool size and consistency.
  • Individualized programs are necessary for proper bowel management, given the different manifestations of defecation dysfunction seen in patients with myelomeningocele. Consistency of the routine is extremely important for avoidance of accidents. Behavior modification and biofeedback techniques have increased success in achieving bowel continence in some children with myelomeningocele.

Surgical Intervention

• Neurosurgical
• • Closure of the myelomeningocele is performed immediately after birth if external CSF leakage is present and typically within the first 24-48 hours in the absence of CSF leakage. The surgery can be delayed for several days without additional morbidity or mortality. A delay gives families more time to deal with the shock and learn about the condition to enable them to participate to a greater degree in the decision-making process.
  • Steps in the closure procedure include extensive undermining of the skin, dissection of the neural plaque that is replaced into the spinal canal, and meticulous watertight closure of the dura, fascia, subcutaneous tissues, and skin.
  • Perioperative complications include wound infection, CNS infection, delayed wound healing, CSF leakage, additional neurologic damage to the cauda equina, and acute hydrocephalus. Long-term complications include cord tethering and progressive hydrocephalus.
  • Although hydrocephalus arrests spontaneously in a few cases, 80-90% of children with myelomeningocele ultimately require shunting. Ventriculoperitoneal shunting is the preferred modality. Alternatives include ventriculoatrial and ventriculopleural shunting. Perioperative complications include intracerebral and/or intraventricular hemorrhage, bowel perforation, and infection. Long-term complications include infection, overdrainage or underdrainage, and obstruction of the shunt system.
  • The Chiari II malformation results in problems severe enough to warrant surgical intervention in approximately 15-35% of patients with myelomeningocele. Patients with vocal cord weakness or paralysis, significant stridor, apnea, aspiration, or sensorimotor deterioration are considered potential surgical candidates. If effective control of hydrocephalus does not improve symptoms, surgical repair of the Chiari II malformation is pursued. This involves an occipital craniotomy and upper cervical laminectomy for decompression of the medulla and upper cervical spinal cord.
  • The tethered cord syndrome requires treatment in approximately 33% of patients with myelomeningocele. It is indicated for those patients with progressive clinical signs and symptoms in order to prevent further deterioration and potentially restore the previous level of function. Surgical release is performed by dissection of the scarred portion of the spinal cord in the area of the myelomeningocele repair.
  • Symptomatic syringomyelia may resolve after shunt insertion or revision. If symptoms persist in the absence of a shunt malfunction, surgical intervention may involve a Chiari decompression or direct shunting of the syrinx.
• Orthopedic
• • Musculoskeletal problems in myelomeningocele can be congenital or acquired, and often require orthopedic intervention. Orthopedic surgeries are directed toward functional improvement as opposed to correction of radiologic findings.
  • Spinal deformities are common, and progressive kyphosis or scoliosis may lead to a decline in functional status and to an increased risk for the development of decubiti and potential cardiopulmonary compromise.
  • Spinal stabilization is necessary to correct kyphosis, which may be related to congenital vertebral malformation or may be a result of the collapsing spine in high-thoracic paraplegia. More recent techniques such as decancellation and longer fusions along with earlier intervention (around age 3 y) have improved outcomes.
  • Scoliosis affects 30-50% of children with myelomeningocele and may be the result of asymmetric muscle forces, unilateral hip dislocation and pelvic obliquity, or an underlying progressive neurologic process such as tethered cord syndrome. Spinal orthotic devices may serve as a temporizing measure, but growing children with spinal curves greater than 30-35°° typically require surgical fusion. Lumbosacral fusions are avoided in order to preserve pelvic motion.
  • Paralytic muscle imbalance around the hip joints may lead to progressive hip dislocation. This typically occurs in early childhood in patients with high- and mid-lumbar lesions and in late childhood or adolescence in children with low-lumbar lesions. The literature evaluating the benefits of surgical relocation of hips reflects ongoing controversy surrounding the topic. No good evidence supports the functional benefits of hip relocation surgery in patients with lumbar lesions. Surgery to release contractures limiting motion at the hip and causing an asymmetric gait is recommended in patients with low-lumbar myelomeningocele and hip dislocation. Surgery for relocation of the hips is indicated for patients with sacral-level lesions who ambulate without support.
  • Common knee deformities include flexion and extension contractures, usually related to a capsular contracture. Surgery is indicated when the contracture causes a functional problem. Types of surgery include a simple tenotomy of the knee flexor tendons in the child with a high-level lesion or lengthening of the tendons in the child with a low-lumbar or sacral-level lesion, for whom preservation of hamstring function is important. Extension contractures are less common, but they interfere with sitting and are associated with hip dislocation and clubfoot. If the contracture is not amenable to conservative measures (eg, serial casting), an extensor tendon release is performed.
  • The most common rotational deformities seen in myelomeningocele are internal and external tibial torsion. These may result in significant gait deviations that affect functional mobility. In addition, the combination of femoral anteversion and excessive external tibial torsion are often seen in patients with the condition at low lumbar and sacral levels. This can lead to abnormal valgus stress at the knee and can cause knee pain and arthritis in adult life. Some rotational malformations improve with growth and/or with the use of bracing. If improvement is not noted by age 6 years, surgical correction is indicated.
  • Foot and ankle deformities may cause skin breakdown and prevent the patient from wearing shoes and/or orthotics. Since almost all patients with myelomeningocele require orthoses, the goal of orthopedic treatment is achievement of a supple and flexible foot. In the case of clubfoot, most patients need surgical correction in the first year of life, usually involving multiple soft tissue release procedures with tendon excisions. In older children, other types of deformities (eg, equinovalgus, cavus, calcaneovarus, calcaneovalgus) may require extra-articular bony procedures and tenotomies in order to correct the muscle imbalances and achieve a supple plantigrade foot that can tolerate a brace. Arthrodesis is rarely indicated but may be necessary in cases of severe ankle instability.
• Urologic
• • Intermittent catheterization may not be feasible for, or accepted by, the caregivers of infants and young children. In these cases, a temporary vesicostomy, in which an opening in the bladder is brought out to the level of the skin, may be a useful alternative. Vesicostomies can drain spontaneously and/or be catheterized.
  • Children whose high bladder pressures are refractory to intermittent catheterization and/or medications (approximately 15-30% of patients with myelomeningocele) are candidates for surgical intervention. Various surgical techniques for augmentation cystoplasty and urinary diversion have been described in the literature.

Consultations

Manifestations of myelomeningocele change as the infant develops. Multidisciplinary interventions are required to prevent the progressive deterioration of the multiple body systems affected. The treatment team usually consists of pediatric specialists in physical medicine and rehabilitation, neurosurgery, urology, and orthopedics along with pediatric nursing, physical therapy, occupational and recreational therapy, psychology, and medical social work. A multidisciplinary clinic setting facilitates the coordination of comprehensive care for the patients.

• Children with myelomeningocele should be scheduled for regular follow-up visits in the multidisciplinary clinic every 6 months throughout childhood and annually thereafter.
• More frequent visits with certain specialists may be necessary, depending on the outstanding medical and surgical issues that present at different times during the child's development.

Other Treatment

• Clean intermittent catheterization on a regular schedule is preferred to long-term indwelling catheters, as it keeps children drier, less prone to infection, and more in control of urinary function. This technique is used from birth, if indicated, for reduction of bladder pressures or may be initiated to establish social continence at a developmentally appropriate time.
• Intravesical transurethral bladder stimulation has been shown to improve bladder compliance through increased functional bladder capacity and to improve sensation; however, this type of stimulation has been less successful in achieving volitional voiding and total urinary control.
• Hormonal treatments are increasingly being used for precocious puberty and growth hormone deficiency in children with myelomeningocele. A recent series of children with myelomeningocele treated with growth hormone showed that their near adult stature was greater and that they were less overweight compared with untreated adults with myelomeningocele.
• Success with the RGO requires proper selection, strong motivation, and realistic goals and expectations. The patient and caregivers also must be able to participate in a training program and make frequent visits for orthotic repairs.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The medications used most frequently in myelomeningocele are for treatment of neurogenic bladder dysfunction. These medications are used in conjunction with some form of bladder emptying technique to prevent upper urinary tract complications and to facilitate social continence.

Drug Category: Anticholinergics

Employed to suppress detrusor overactivity.

Drug Category: Tricyclic antidepressants

May act through anticholinergic effects

Drug Category: Alpha-adrenergic antagonists

Alpha-adrenergic receptors are found in the bladder neck and urethra. Alpha-adrenergic antagonists decrease bladder outlet resistance, increase urinary flow rate, and improve bladder emptying.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• After initial hospitalization at birth, patients with myelomeningocele are admitted frequently for medical or neurologic complications, as well as neurosurgical, orthopedic, and urologic procedures. Inpatient rehabilitation may be indicated after any of these admissions to maximize the child's recovery and function.

Further Outpatient Care

• Please see the Physical Therapy, Occupational Therapy, Recreational Therapy, and Consultations sections.

In/Out Patient Meds

• The medications used most frequently in myelomeningocele are for treatment of neurogenic bladder and bowel dysfunction.

Deterrence

• Over the last 3 decades, the incidence of myelomeningocele has undergone a significant decline, both in the United States and worldwide. This decline is related to increasing availability and accuracy of prenatal diagnosis with the option for early pregnancy termination and the introduction of primary prevention in the form of folic acid therapy in the periconceptual phase.

Complications

• Progressive neurologic deficits of delayed onset in patients with myelomeningocele are often related to uncontrolled hydrocephalus and the Chiari II malformation.
• • Repeated, prolonged shunt dysfunction as well as CNS infections are associated with an increased risk of functional and cognitive deficits. Shunt dysfunction may result in an acute or chronic rise in intracranial pressure and occurs more commonly in the first 2 years of life. Diagnosis may be difficult, as early signs and symptoms are extremely variable and often nonspecific.
  • In general, infants present with symptoms of lethargy, poor feeding, irritability, stridor, ocular motor incoordination, and development delay. Older children may present with cognitive or behavioral changes, decreased strength, increased spasticity, changes in bowel or bladder function, lower cranial nerve dysfunction, back pain, and worsening spinal or lower extremity orthopedic deformities. Some patients may present with only papilledema. In any patient with myelomeningocele who presents with deterioration in neurologic, orthopedic, or urologic function, uncontrolled hydrocephalus should be excluded as a cause before any other treatment is pursued.
  • The Chiari type II malformation may cause acute or subacute signs and symptoms of lower brainstem and/or upper cervical spinal cord compression, including laryngeal and pharyngeal paralysis, apnea, swallowing difficulty, respiratory stridor, nystagmus, and upper extremity weakness. Treatment initially involves control of hydrocephalus. Surgical decompression of the Chiari malformation is indicated for those patients with severe or progressive symptoms.
• Other causes of delayed neurologic deterioration in myelomeningocele are due to spinal cord pathology such as tethered cord syndrome and syringomyelia. Tethered cord syndrome occurs more frequently during periods of rapid growth. Early recognition and treatment of these conditions may improve or stabilize neurologic function. However, symptoms are often vague and insidious and considerable clinical judgment is necessary to determine which patients might benefit from treatment.
• Skin breakdown occurs in 85-95% of children with myelomeningocele before young adulthood. Recurrent decubiti can lead to prolonged morbidity and functional disability. Healing can occur if the precipitating mechanical factors are eliminated. Plastic surgical correction may be necessary in severe cases and may involve orthopedic correction of underlying postural abnormalities.
• • The sites and causes of skin breakdown vary by age and lesion level. Skin breakdown on the lower limb occurs in 30-50% of cases in all lesion-level groups.
  • The most common areas of breakdown in the thoracic-level group are the perineum and above the apex of the kyphotic curve. Overall, tissue ischemia from pressure necrosis is the most common etiology.
  • Older children may have higher risk of skin breakdown because of increased pressure of a larger body habitus, asymmetric weight bearing from acquired musculoskeletal deformities, and lower limb vascular insufficiency or venous stasis.
  • Other frequent causes more prevalent in the younger child include casts or orthotic devices, skin maceration from urine and stool soiling, friction, shear, and burns.
• Bone mineral density is decreased in patients with myelomeningocele. Markers of bone reabsorption were found more frequently in both limited ambulators and nonambulators than in children who ambulated regularly. Children with myelomeningocele are at higher risk of lower extremity fractures. Reduced muscle activity in the paralyzed limb and decreased weight-bearing forces result in decreased bone mass. In addition, many fractures occur after orthopedic interventions, especially after procedures associated with cast immobilization. Fractures in myelomeningocele tend to heal quickly, and excessive callus formation often is seen. Relative immobilization (ie, short casting times and early weight bearing) is the standard recommendation for healing after fractures. The goal is maintaining functional alignment and rotation without compromising the patient's ability to stand and ambulate.
• Obesity is prevalent in children with myelomeningocele, especially those with high-lumbar and thoracic-level lesions because of reduced capacity for caloric expenditure. The decreased muscle mass of the lower body musculature results in a lower basal metabolic rate. In addition, activity levels generally are lower than in unaffected children, both as a direct result of lesion-related mobility deficits and as an indirect result of decreased opportunities for disabled children to participate in physical play. Obesity can exert negative impact on self-image and further perpetuate a cycle of inactivity and overeating. Because of their decreased linear limb growth and spine growth, patients with myelomeningocele should be monitored for weight using arm span measurements, as opposed to ratios of height versus weight.
• Latex sensitization is more common in patients with myelomeningocele, likely due to both a genetic predisposition and a higher degree of exposure. The number of surgical interventions (particularly orthopedic and urological procedures), the presence of a ventriculoperitoneal shunt, and total serum immunoglobulin E levels have been associated with latex allergy in children with myelomeningocele. Establishment of a latex-free environment for surgery has resulted in a decrease in sensitization of these patients to latex.

Prognosis

• Recent studies of children with prenatally diagnosed myelomeningocele suggest that less severe ventriculomegaly and a lower anatomic level of lesion on prenatal ultrasound predict better developmental outcomes in childhood.
• The ability to ambulate is dependent on and directly correlated with the functional sensorimotor level. Studies have shown that approximately 50-60% of young adult patients ambulate household or community distances, with about 20% of these patients using some orthotic or assistive device. The other 50% of patients use wheelchairs as their primary form of mobility. Approximately 20% of these individuals ambulate with orthotics and assistive devices as a form of therapeutic exercise.
• • Several studies have shown that ambulation in patients with myelomeningocele is related to the strength of certain key muscles, including the iliopsoas, gluteus medius, hamstrings, and/or quadriceps. Specifically, a motor neurologic level of L5 or quadriceps strength graded as good in the first 3 years of life is predictive of a good prognosis for community ambulation. Gluteus medius strength was the best predictor of a need for gait aids and orthoses. In a 25-year follow up study on young adults with myelomeningocele, no patient with a lesion at L3 or above ambulated a majority of the time.
  • Maximal ability to ambulate usually is achieved by the time the child reaches age 8-9 years. Studies have shown that a majority of preadolescent patients, even those with higher-level lesions, are community ambulators when they receive aggressive multidisciplinary interventions. However, after adolescence, community ambulation decreases to approximately 50%. The ability to ambulate tends to decline in the second decade of life because of increased body dimensions and higher energy requirements. Lower extremity muscle deterioration also may play a role. Functional decline as patients with myelomeningocele age also can be exacerbated by obesity, decubiti, and psychological issues.
• Except for sphincter control, independence in activities of daily living is likely for children born with myelomeningocele without hydrocephalus. For those born with myelomeningocele and hydrocephalus, those with a level of lesion of L3 or below are likely to be independent for almost all activities of daily living except sphincter control. Those with higher-level lesions are at significant risk for dependence in activities of daily living.
• With proper urologic management, more than 95% of children with myelomeningocele continue to have normal renal function. The psychosocial consequence of bowel and bladder incontinence can have a dramatic impact on children with myelomeningocele, especially in adolescence. The data on continence from the literature is variable, which in part reflects inconsistencies in the definition of social continence. Studies report 40-85% achievement of bladder continence and 50-85% achievement of bowel continence. Approximately 25% of patients are continent of both bowel and bladder. The likelihood of social continence improves when training is instituted before age 7 years.
• Studies of adults with myelomeningocele have shown that about 20-30% secure gainful employment. In one study, employment status was related to lesion level and motor independence. However, motor independence was not found to be related to self-reported quality of life or range of life experiences.
• Several studies have shown a greater number of shunt revisions are associated with reduced independence and achievement in adulthood. This suggests that close medical management in order to minimize episodes of increased intracranial pressure may improve adult employment and quality of life.
• Perceived family environment may explain different levels of participation of patients with myelomeningocele in employment, community mobility, and social activity as an adult, even beyond what can be explained by lesion level and intelligence. A positive correlation exists between perceived family encouragement of independence and outcomes in young adults with myelomeningocele.

Patient Education

• Institute measures to avoid development of soft tissue contractures in the neonatal period. Physical and/or occupational therapists provide caregivers with instruction in handling and positioning techniques. In the first several years of life, recommend incorporation of stretching and strengthening exercises into a home program performed by the caregivers and later into play and physical education activities at school.
• Instruct preschool and school-aged children with myelomeningocele in the use of adaptive equipment and alternative methods for self-care and performance of ADL. To become independent by school age, young children with myelomeningocele need to become active participants in skin care, bowel and bladder management, and donning and doffing of orthotics, in addition to traditional ADL tasks such as feeding and dressing. Acquisition of ADL skills often is influenced by attitudes and expectations, so the multidisciplinary team members need to emphasize carryover of ADL skills in the home and school environments by providing anticipatory guidance to parents and caregivers.
• Strategies for prevention of skin breakdown first are directed at parents and caregivers, but children with myelomeningocele should be encouraged from an early age to take responsibility for their own skin care. Parents must first be made aware of the areas of abnormal sensation. Necessary precautions include daily skin inspections, pressure relief, avoidance of exposure to extreme temperatures and harmful surfaces, and frequent monitoring of shoes and orthotics.
• Self-catheterization techniques should be introduced during the later preschool years to promote normal progress toward independence. Mastery of self-catheterization in patients with myelomeningocele usually is achieved by the age of 6-8 years, depending on the severity of cognitive and motor involvement.
• A functional environment should be created for the patient at home and school to facilitate efficient independent functioning.
• For excellent patient education resources, visit eMedicine's Brain and Nervous System Center and Kidneys and Urinary System Center. Also, see eMedicine's patient education articles Spina Bifida and Bladder Control Problems.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to monitor the urinary tract of patients with myelomeningocele and to recognize the signs of renal decompensation may result in increased mortality and morbidity.

Special Concerns

• As a group, patients with myelomeningocele have intelligence scores below the population average, but within the normal range. Lower scores are associated with higher-level lesions, hydrocephalus, CNS infections, and intracranial bleeding.
• • Children with myelomeningocele tend to demonstrate generalized deficits in both visual memory and auditory/verbal memory
  • Verbal subtest scores usually exceed performance subtest scores, with visual-spatial organizational deficits that may be explained in part by upper limb discoordination and/or memory deficits.
  • The term "cocktail personality" has been applied to a subgroup of patients with hydrocephalus who appear to have advanced expressive language skills. The speech of these individuals typically is verbose, but it tends to lack content and contains jargon and many clichés. This pattern often is associated with poor comprehension skills and reflects significant cognitive impairments and functional deficits.
• Approximately 75% of children with myelomeningocele have an IQ higher than 80. Among those whose intelligence is normal, 60% are learning disabled, with the most common feature being a nonverbal learning disability. Particular deficits are seen in mathematics, sequencing, visual perceptual skills, and problem solving. Prevalence of attention problems has been estimated to be 30-40%.
• Sexual education and counseling should begin early to help adolescents with myelomeningocele make a positive adjustment to adolescence and to help them avoid misinformation. Sex education, including accurate information about safe sex, should be included in the routine health care maintenance of the older child and adolescent with myelomeningocele. Studies of young people with myelomeningocele have shown that, although many are involved in intimate relationships, most had inadequate knowledge about sexuality and reproductive health issues related to their condition.
• • Females with myelomeningocele go through puberty 1-2 years earlier than their unaffected peers. Sexual precocity is associated with hydrocephalus and obesity. Abnormal genital sensation is typical, but some female patients with myelomeningocele are able to achieve orgasm. Fertility is not affected in females with myelomeningocele; however, pregnancy carries increased risk of urinary tract infection, back pain, and perineal prolapse postpartum.
  • Young men with myelomeningocele have abnormal genital sensation, decreased ability to achieve and sustain erections, and decreased fertility. However, the potential for ejaculation and reproduction must be assessed for each individual patient. Implantable penile prosthetic devices, vacuum tumescence devices, and electrical stimulation have been used for some patients unable to achieve erections.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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