AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Spina bifida cystica (myelomeningocele) is the most complex but treatable central nervous system abnormality. Recognized 4 thousand years ago, it is visibly evident at birth.

Malformations of the brain and spinal cord can occur during embryologic development. Varying in severity, neural tube defects have a range of presentations, from stillbirth to incidental radiographic findings of spina bifida occulta (SBO). Treatment advances have allowed an increasing number of patients with neural tube defects to participate and be productive in mainstream society.

The need for a team approach is recognized in contemporary treatment of spina bifida. Bringing together a number of medical and surgical specialists can help to spare parents the strain and exhaustion of coordinating with multiple doctors and can ensure availability of necessary services. The orthopedic surgeon assumes a significant role in coordinating the many treatment components that together allow patients to gain maximum function and, particularly, independence.

Participation in the care of patients with major, chronic physical disabilities requires commitment, coordination, and access to extensive clinical resources. Improved survival rates in patients with spina bifida can be expected with treatment; quality of life is at least partially dependent on the speed, efficiency, and comprehensiveness of that treatment from birth.

People with spina bifida may have physical challenges, but treatment rewards patients and, in turn, the overall population as these individuals become increasingly able to contribute to society.

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.

History of the Procedure

Because the spinal cord and, thus, the central nervous system are exposed in spina bifida, persons with this disease were not expected to survive in the preantibiotic era. Those who did survive had severe handicaps. Debate over whether surgical treatment should be offered or whether the disease should be allowed to take its natural course has been resolved in favor of treatment. The results of withheld treatment are well documented, with most patients dying within the first 6-12 months.

Malcolm Menelaus pioneered many advances in the treatment of patients with spina bifida and summarized them in his classic book The Orthopaedic Management of Spina Bifida Cystica (1980).

The many orthopedic procedures used in spina bifida treatment include the following:

• Closure of the defect over the spinal cord, without which survival is jeopardized
• Spinal deformity reconstruction, which may be particularly challenging because of posterior element deficiencies and can lead to instrumentation and fusion failures, infection from the neurogenic bladder, a closure scar, and ulcers from distal insensate skin
• Lower-extremity deformity correction, which is necessitated by muscle imbalance forces

Beyond closure, which is a neurosurgical procedure, shunting may be needed for hydrocephalus, including normal-pressure hydrocephalus, and many urologic procedures may be required for the neurogenic bladder.

Customary techniques have been used for spinal deformity procedures, but anterior procedures now are being more frequently combined with the posterior approach to produce a satisfactory fusion. Lower-extremity procedures, particularly hip reduction, have been the most controversial. Opinions differ as to whether these aid in seating and ambulation. More recently, gait analysis has been used to analyze specific candidates who possess motor strength in the quadriceps in the range of "good plus" and who also have hip dysplasia or dislocation. Procedures distal to the hip often are similar to those for polio but generally are aimed at maintaining the ability to brace the limb in order to maximize accessibility and independence. Procedures below the hip are directed toward reducing deformity, releasing contractures, and balancing muscle forces from the variable neurologic lesions.

Problem

Spina bifida is a variable defect in which the vertebral arch of the spinal column is either incompletely formed or absent. The term bifida is from the Latin bifidus, or "left in 2 parts." Although the condition has also been referred to as myelodysplasia and myelomeningocele, spina bifida generally has been accepted as the preferred term, specifically by the American Academy of Orthopaedic Surgeons. Rachischisis posterior, the equivalent Greek term, is derived from rachis, meaning spine, and schisis, meaning division (spondyloschisis in Latin).

Spina bifida cystica

Spina bifida cystica (myelomeningocele), a neural tube defect, can occur anywhere along the spinal axis but most commonly is found in the lumbar region.

In spina bifida cystica, the spine is bifid and a cyst forms. A meningocele, a cystic swelling of the dura and arachnoid, protrudes through the spina bifida defect in the vertebral arch. A person with a meningocele may have no neurologic sequelae. A myelomeningocele, the name of which refers to the myelo, or spinal cord, also may occur, protruding through the defect. According to Menelaus, the myelomeningocele form of spina bifida cystica is the most significant and common type of spina bifida, accounting for 94% of cases. (SBO is not included in this figure.) The most severe form of spina bifida cystica is the myelocele, or myeloschisis, variety, in which the open neural plate is covered secondarily by epithelium and the neural plate has spread out onto the surface.

A child born with myelomeningocele requires specialty care and transfer to a center where neonatal surgery and closure can be performed. Surgery involves freeing lateral muscles and skin for coverage and attempting to form a closure of the neural elements with minimal scarring, because the late complication of a tethered cord has frequent and severe consequences. Further follow-up at a comprehensive, multidisciplinary clinic gives the patient access to a range of specialists, allowing the child to receive an extensive array of essential services without necessitating separate visits to multiple physicians.

Spina bifida occulta

SBO is a limited defect of the vertebral arch that does not involve protrusion of the cord or membrane. Most often occurring at the lumbosacral junction, SBO appears as an incidental radiograph finding in up to 10% of the healthy population.

Syringomeningocele

Syringomeningocele is another form of spina bifida. The Greek word syrinx, meaning tube or plate, is combined with meninx (membrane) and kele (tumor). The term thus describes a hollow center, with the spinal fluid connecting with the central canal of the cord enclosed by a membrane with very little cord substance.

Syringomyelocele

Syringomyelocele is a type of spina bifida in which protrusion of the membranes and spinal cord lead to increased fluid in the central canal, attenuating the cord tissue against a thin-walled sac. Syringomyelia, or hydrosyringomyelia, is the presence of cavities in the spinal cord, which may occur as a result of the breakdown of gliomatous new formations.

Diastematomyelia

Diastematomyelia, from the Greek root diastema (interval) and myelon (marrow), is sometimes accompanied by a bony septum. This septum may cause a tethered cord and irreversible neurologic loss from differential growth of the spinal canal exceeding the earlier developing spinal cord, but a tethered cord also may exist without a bony septum.

Myelodysplasia

Myelodysplasia is from the Greek term myelos, meaning spinal cord, combined with dys, for difficult, and plasi, for molding. This is an abnormality in the development of the cord and, thus, is an inappropriate description for SBO, in which the cord is normal. As previously stated, however, it has nonetheless been used as a synonym for spina bifida.

Dysraphia

Dysraphia, from the Greek term raphia and its root, rhaphe, a seam, is a defective fusion of parts that normally unite. This term could be applied to the vertebral arch.

Arnold-Chiari deformity

Arnold-Chiari deformity is a malformation of the cerebellum, with elongation of the cerebellar tonsils. The cerebellum is drawn into the fourth ventricle. The condition also is characterized by smallness of the medulla and pons and by internal hydrocephalus. In fact, all patients with spina bifida cystica (failure to close caudally) have some form of Arnold-Chiari malformation (failure to close cranially).

Craniorachischisis

Craniorachischisis (total dysraphism) is a condition in which the brain and spinal cord are exposed. This often results in early spontaneous abortion, commonly associated with malformations of other organ systems. In anencephaly, brain tissue is exposed through a defect in the scalp and skull, but the spinal cord generally remains intact.

Frequency

The incidence of spina bifida has been estimated at 1-2 persons per 1000 population, with certain populations having a significantly greater incidence based on genetic predilection. Folate fortification of enriched grain products has been mandatory in the United States since 1998; research indicates that folate can reduce the incidence of neural tube defects by about 70% and can also decrease the severity of these defects when they occur (Holmes, 1988; Milunsky et al, 1989; Mulinare et al, 1988).

Siblings of patients with spina bifida have an increased incidence of neural tube defects. Consequently, following the birth of a child with spina bifida, amniocentesis is suggested during subsequent pregnancies in order to monitor fetoprotein (an indicator of failed spine closure and exposure of neural elements to the amniotic fluid). Intrauterine surgery for spina bifida has been performed, and early successes have promoted and justified further studies. A genetic defect has been identified in families with spina bifida.

The average worldwide incidence of spina bifida is 1 case per 1000 births, but marked geographic variations occur. The highest rates are found in parts of the British Isles, mainly Ireland and Wales, where 3-4 cases of myelomeningocele per 1000 population have been reported, along with more than 6 cases of anencephaly (both live births and stillbirths) per 1000 population. The reported overall incidence of myelomeningocele in the British Isles is 2-3.5 cases per 1000 births. In France, Norway, Hungary, Czechoslovakia, Yugoslavia, and Japan, a low prevalence is reported: 0.1-0.6 cases per 1000 live births. In the United States, a declining prevalence has been noted, with the incidence being higher on the East Coast than on the West Coast. The prevalence in African Americans (0.1-0.4 case per 1000 live births) is lower than that in white Americans (1 case per 1000 live births) (Cotton, 1993; Lemire, 1988).

Immigrants from Ireland have a higher prevalence of spina bifida than do nonimmigrants, suggesting a complex genetic relationship. A higher incidence in females than in males has been observed in anencephaly but not in myelomeningocele. An association has been reported with infertility and with antiepileptic drugs, particularly valproate and carbamazepine.

Etiology

A multifactorial genetic inheritance has been proposed as the cause of spina bifida, coupled with environmental factors, of which nutrition, including folic acid intake, are key. Cytoplasmic factors, polygenic inheritance, chromosomal aberrations, and environmental influences (eg, teratogens) have all been considered as possible causes. Prenatal vitamins, especially folic acid, are recommended to discourage the condition's development.

Neural tube defects occur between the 17th and 30th day of gestation, at a time when the mother may not be aware that she is pregnant and the fetus is estimated to be about the size of a grain of rice.

The fetal presence of an open neural tube defect is marked by an elevated alpha-fetoprotein level in the amniotic fluid. Peak concentrations of alpha-fetoprotein in the 13th to 15th weeks of pregnancy permit diagnosis, and ultrasound confirmation with amniocentesis generally is possible at 15-18 weeks. Encephaloceles or skin-covered myeloceles are unlikely to be detected by alpha-fetoprotein.

Following closure of the rostral neuropore, malformations of the central nervous system can arise (postneurulation) in association with neural tube defects. These include hydrocephalus, cephalocele, and the Arnold-Chiari malformations. Prenatal diagnosis and ultrasound confirmation allow for preparation and parental referral to appropriate care services. The pathogenesis of spina bifida has been suggested to involve a defect in neural tube closure or failure of the neural tube to completely close.

During prenatal development, neuroectoderm thickens into the neural plate, which then folds into a neural groove by the time somites appear. The groove deepens to become the neural tube, and dorsal fusion begins centrally, extending cephalad and caudally, with the cephalad pole fusing at the 25th day. The ventricle becomes permeable at the 6th to 8th week of gestation but apparently does not proceed normally in patients with myelomeningocele.

Some studies suggest that an increased amount of neural crest material in the defect prevents the neural tube's closure. Another hypothesis is that an already closed tube ruptures; increased permeability of the rhombic groove leads to greater cerebrospinal fluid (CSF) secretion and increased luminal pressure, with the tube then expanding and essentially splitting the neural element at its weakest areas (ie, the cephalic and caudal ends). Subsequent research by McLone and Knepper (1989) supports the latter hypothesis and details the implications of this defect on the entire central nervous system.

Pathophysiology

Spina bifida cystica causes a problem when the meningeal cyst (meningocele) includes cord tissue extending into the cyst (in which case, it is a myelomeningocele). The condition is also of particular concern when the neural tube is completely open and the ependymal layer is exposed as a myelocele or myeloschisis. Meningocele alone may cause no neurologic problems if the cord is confined to the vertebral canal.

Myelomeningocele is the most common form of spina bifida, accounting for 94% of cases. SBO should be differentiated from spina bifida cystica. The term spina bifida does not refer to SBO. SBO may be seen in a very large number of healthy adults. Some contend that it could be found in up to one third of healthy adults if imaging studies were used to analyze the posterior vertebral arch.

Unprotected neural elements are at severe risk during delivery. (Intrauterine surgery, associated with cesarean delivery, has been proposed for cases of spina bifida, with some favorable results reported at selected centers.) The sequelae of the neural tube defect follow directly from this lack of protection, occurring mechanically or resulting from desiccation, scarring with closure, and/or a lack of vascular support or from other insults to the delicate neural elements.

The neurologic damage generally results in a neurogenic bowel and bladder, which leads to incontinence. With a lack of neural input, a contracted bladder causes hydronephrosis along with infections and renal failure, which may be the prime determinant of longevity in patients with spina bifida. As a pattern, neurologic innervation is not symmetrical between lower-limb flexors and extensors, as the corresponding levels are lower (caudal) for the extensors than for the flexors. Generally, muscular imbalance is present, which results in joint contractures and developmental problems, such as hip dislocation and spinal deformities. Normal intelligence can be expected with aggressive shunting for hydrocephalus, although a subtle defect in coordination may be associated with the cerebellar deficiency from the Arnold-Chiari malformation. Seizure activity secondary to the neural tube defect may be noted.

Clinical

Patients who are born with a sac containing neural elements of the spine require neurosurgical closure of the defect in the neonatal period. They should be referred to an interdisciplinary clinic that includes the services of an orthopedic surgeon.

Although SBO is common and almost always without consequence, some developmental abnormalities may occur—such as a spinal cord lipoma or a fibrous cord—that can cause subtle or rare neurologic signs.

A fibrous cord may extend from an interdural component of one of these developmental abnormalities to the skin, producing a dimple, an area of pigmentation, or a hairy patch at the base of the spine; such symptoms can be noted on physical examination. Patients with a fibrous cord may have problems with micturition, or they may have subtle neurologic signs, such as a foot deformity (most commonly, a cavus foot). A prompt and thorough investigation is mandatory for any progressive neurologic signs. When a lipoma is present, there may be a lipomeningocele, a lipomyelomeningocele, or a lipomyelocele. These may be associated with areas of fluid in the cord, which may be a syringomyelia.

From a neurologic standpoint, the Arnold-Chiari II malformation may be accompanied by temporary stridor and/or apnea, but these problems rarely are severe. A varying degree of interference with cerebellar function seems to occur, particularly with balance and coordination, which has a significant influence on ambulation, the results of physical therapy, and overall orthopedic care. Failure to control a seizure disorder, recurrence of hydrocephalus, or even low-pressure hydrocephalus can cause subtle coordination defects and interruption of some cognitive functions.

The tethered cord may be signaled by foot deformities that previously braced easily, new onset of hip dislocation, or worsening of a spinal deformity, particularly scoliosis. Progressive neurologic defects in growing children may suggest a lack of extensibility of the spine or suggest that the spine is tethered and low lying in the lumbar canal, with the potential for progressive, irreversible neurologic damage that requires surgical release.

Height and weight should be assessed for patients with spina bifida. Excessive weight impedes maximal independence and ambulation. Height may be significantly impaired because of an associated growth hormone deficiency. Growth spurts require close monitoring for any deformities, from scoliosis to deformities of the lower extremities.

INDICATIONS

Section 3 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Patients with spina bifida have variable neurologic deficits that characteristically cause deformity as a result of muscle imbalance forces. Unopposed muscle pull can cause spinal deformity, progressive lower-extremity contractures, hip dislocations, and, less commonly, dislocations in other joints.

The assessment of the patient with spina bifida needs to focus on function (ie, accessibility, gait, independence), and treatment should be directed at addressing any deformity that interferes with the patient's potential. When serial follow-up examination demonstrates worsening function associated with progression of a deformity, surgery should be considered to correct the deformity in combination with release of the deformity and rebalancing of muscle forces around the involved joint as necessary.

RELEVANT ANATOMY

Section 4 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Pertinent anatomy includes neural innervation, particularly of the lower extremities. Examination of neurologic deficit helps determine the functional level at which the spina bifida cystica lesion has interrupted function. The myelomeningocele lesion is unique; its effects are significantly different from those of poliomyelitis, in which anterior horn cells are injured; thus, with a myelomeningocele, motor function is deficient, but sensation is preserved. The symptoms are also unlike those of cerebral palsy, in which spasticity is common. This is because the spina bifida lesion is generally flaccid, although in some cases a myelomeningocele may be associated with a measure of spasticity.

At birth, 2 main types of neurologic involvement can be recognized. Type I, which is considered typical, is present in one third of patients in the neonatal period. A certain segmental level is involved, with resulting flaccid paralysis, loss of sensation, and loss of reflexes. Type II is present in two thirds of patients and is characterized by the interruption of long track signs, with preservation of pure reflex activity, although it may be grossly exaggerated in isolated distal segments. This can present as 3 subtypes, as follows:

• Cord function is intact to a certain level, below which a gap is manifested by flaccid paralysis, loss of sensation, and loss of reflexes. More distally, isolated cord function is evident from exaggerated reflex activity.
• The gap in cord function is narrow, virtually amounting to a transection. (This condition occurs especially in newborns.) There is no movement of the lower limb when the infant is crying, but there is a wealth of purely reflexive activity, including flexor withdrawal, which can be elicited by direct stimulation.
• If transection of the long track is incomplete, the child will have spastic paraplegia with preservation of some voluntary movement and sensation. In up to 5% of patients, a hemimyelomeningocele is present, in which one leg is affected with a type I or II lesion and the other may basically be unaffected.

After recognizing the complexity of the actual neurologic deficit, it is clinically useful—because the function and treatment of patients with spina bifida follow broad guidelines—to categorize these patients into general groups. Generally, neurologic levels are grouped as thoracic, upper lumbar (L1, L2, L3), lower lumbar (L4, L5), and sacral.

Independent ambulation generally is a function of having an intact quadriceps muscle with good-plus or excellent-plus strength levels. Patients who do not have adequate quadriceps function may require bilateral Lofstrand crutches or may be primarily restricted to a wheelchair. In such cases, reduction of hip dislocation typically has not been advised because the effect on a person who cannot ambulate is not as consequential as it would be upon a person who can (although some hip dislocations may have a significant impact on a patient's ability to sit properly). Functional ambulation generally is described according to the following levels, developed by Hoffer and colleagues (1973):

• Community ambulator - Indoors or outdoors, crutches with or without braces
• Household ambulator - Only indoors, crutches with or without braces
• Nonfunctional ambulator - Wheelchair, crutches, and braces, in therapy
• Nonambulator - Wheelchair bound

CONTRAINDICATIONS

Section 5 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Because neurologic impairment is associated with most functional problems, any corrective surgery would presuppose a stable neurologic status. In the patient with spina bifida, a tethered cord may represent a changing neurologic situation that would contraindicate any surgical procedures.

WORKUP

Section 6 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Lab Studies

• In addition to routine laboratory screening examination, testing would include levels of anticonvulsants, urine cultures, and perhaps cystometrograms and skin testing for latex sensitivity. The last can be performed by enzyme-linked immunosorbent assay (ELISA) or skin prick.

Imaging Studies

• Plain radiographs are important for the clinical evaluation for scoliosis, dysplasia, and dislocation of the hip. Ultrasound evaluation and radiographs should be used to assess any area of pain because of the high risk of pathologic fractures.
• A computed tomography scan of the head is appropriate to evaluate for possible recurrent hydrocephalus or a change in the size or function of the ventricles, which might be affected even with normal-pressure hydrocephalus.
• Magnetic resonance imaging provides considerable detailed information regarding the spinal cord and its malformations, including low-lying or tethered cords.

Other Tests

• Gait analysis has been introduced to evaluate patients functionally. It is also used to study muscle innervation, strength, and coordination patterns, which may interfere with ambulation or with a patient's ability to live independently. Gait analysis sometimes has been helpful in evaluating patients for reduction of a dislocated hip and transfer of muscles for imbalances (which lead to progressive deformities, difficulty bracing, and problems with ambulating).

TREATMENT

Section 7 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Medical therapy

All patients with spina bifida require extensive, active, interdisciplinary treatment by a trained and coordinated team. Neonatal neurosurgery is followed by serial examination of muscle strength and joint range of motion. General orthopedic evaluation also is performed, to detect any early changes that may require intervention. In addition, patients should be monitored for appropriate development and be provided with prolonged physical therapy, gym resources, and adaptive training while in school. Subsequent efforts are necessary to encourage, develop, and maintain independence.

The goal of bracing is to allow patients to function at the maximum level permitted by their neurologic lesion and intelligence. Bracing also ensures a normal developmental progression, its aim being to enable patients to ambulate and to participate in appropriate age-related activities. Finally, orthotics should aid in minimizing energy expenditure to maintain mobility levels. In infants aged 9 months and younger, sitting balance and support may be provided with a standard car seat, elevated 45-60°. A car seat may be appropriate to maintain mobility with head and trunk control and to increase upper-extremity strength in children as old as 18 months. A standing frame may be used for those aged 1-2 years to diminish the degree of osteoporosis and to limit the contracture of the hip, knee, and ankle.

A parapodium may be helpful for children aged 3-12 years, allowing patients to gain greater experience in standing and manipulating work with their upper extremities at a table or desk. Because parapodiums are cumbersome, their use is limited as patients get older. Subsequently, a wheelchair can provide mobility and often is used with a molded ankle-foot orthosis (MAFO). As the child has less neurologic input, a knee-ankle-foot orthosis (KAFO) may be helpful in allowing ambulation. Hip-knee-ankle-foot orthoses (HKAFOs) generally are useful in therapy but are not practical for long-term use. The addition of a reciprocating gait orthosis may help in reducing the energy expenditure required for mobility.

Neurosurgical follow-up is required to recognize the complications of hydrocephalus or a possible tethered cord and to monitor any potential causes of seizure activity. Urologic evaluation is necessary to establish a bladder regimen to prevent frequent urologic infections and to recognize and treat early, potential hydronephrosis or other causes of renal damage that can limit life expectancy.

Pediatric evaluation is appropriate for any child and, specifically, should include efforts to help the patient maintain a reasonable weight, because children without ambulation tend to gain excessive weight and develop associated morbidity. Endocrinologically, a growth hormone deficiency may be present, which could cause patients to be about 1 foot shorter than their peers. Consultations with an orthotist, a physical therapist, and a dietitian are appropriate to maintain optimal development and to maximize accessibility and independence.

After childhood, group homes may be used to train patients with spina bifida to live independently. Clearly, these individuals have substantial problems. A supportive clinic and extensive interdisciplinary program are necessary to meet the affected individual's needs. Moreover, their congenital condition requires treatment and intervention involving the patient's entire family, placing significant stress on parents. This is an area of concern for the pediatrician. It is necessary for the physician to counsel parents and family, informing them of the ramifications of the condition and of the surgical and medical care needed to maximize function. While no cure for the patient is possible, the family's overall pessimistic attitudes or unrealistic expectations, as well as parental feelings of guilt, anxiety, and inadequacy, must be addressed.

Customary early follow-up care includes monitoring of head size and condition for potential hydrocephalus, evaluation of sphincters, and progression toward an appropriate bowel and bladder regimen. Early monitoring of motor function in the lower extremities also is necessary and should later consist of serial orthopedic examination. Considerable attention may be needed to prevent the "outhouse syndrome," in which the patient's physical problems give rise to social consequences because of a failure to comply with an appropriate bowel regimen. Clean, intermittent catheterization has been a very helpful adjunct to the preservation of urinary function.

With aggressive shunting of hydrocephalus, normal intelligence can be retained. Progress into mainstream society is possible, and skills can be acquired for lifelong contributions to society.

Surgical therapy

The orthopedic surgeon has a large role in the treatment of patients with spina bifida. This includes long-term monitoring of neurologic status, motor strength, and joint range of motion. Because many patients require some degree of bracing, examination for skin irritation and breakdown and observation of ambulation to assess the functional utility of the braces are helpful in detecting any change in condition or the need for treatment modification.

Spine

In addition to neurologic defects, spinal deformity is common in patients with spina bifida and is very difficult to treat. However, correction and fusion are necessary to arrest progression and complications and are prerequisites for successful treatment of lower-extremity deformities and for reduction of impedances to walking and sitting.

Scoliosis, most commonly paralytic scoliosis, accounts for about 90% of spinal abnormalities in spina bifida (Park, 1985). Paralytic scoliosis is characterized by a single, long curve, midthoracic to sacral, often with pelvic obliquity. Paralytic scoliosis is associated with difficulties balancing when sitting and with ischial pressure sores.

Congenital curves may arise at any level and often are associated with vertebral body abnormalities, such as defects of segmentation and formation, as well as mixed defects. Many curves may have associated syringomyelia.

At 20 years of age, the incidence of a scoliotic curve of more than 30° with a thoracic-level myelomeningocele is almost 90%; with a high lumbar myelomeningocele, about 80%; with a low lumbar myelomeningocele, essentially 25%; and with a sacral-level myelomeningocele, about 10%. Bracing can be used to allow growth without progression of the deformity, to achieve a higher eventual sitting height. However, surgery is indicated for nonflexible curves, progressive problems with recurrent pelvic pressure sores, gross pelvic obliquity, or unacceptable cosmetic deformity, particularly with back pain. The presence of deficiencies in the posterior elements and in the bone stock generally necessitates an anterior and posterior procedure to achieve a reliable arthrodesis (Shurtleff et al, 1976).

Kyphosis of uncommon severity occurs with high-level spina bifida cystica, such that over the T12 level, more than 60% of patients have kyphosis, whereas under that level, only about 10% have a measure of it (Shurtleff et al, 1976).

Patients with a kyphosis of more than 65° have insidious progression; the extensor muscles become flexors when they migrate to a position anterior to the spinal column and, thus, become a deforming force. Kyphosis is associated with a high level of chronic skin ulcerations, difficulty sitting, and problems with access for urinary diversion. It can also lead to difficulties in obtaining a properly fitted orthosis. Therefore, kyphosis requires surgical treatment. Unfortunately, some deformities exceed the capability of the anterior abdominal wall to stretch and accommodate a correction. Reducing the deformity, using either excision or a kyphectomy, with the vertebral bodies excised or debulked and collapsed down, allows correction through shortening of the spine.

Excision is more realistic, as an extremely high incidence of failure is associated with implants. A long fusion is necessary, often with segmental attachment and anterior support because of posterior deficiency of the bone from lack of muscle forces and gravity stresses.

Sacral agenesis may occur in association with a myelomeningocele, and diastematomyelia can be associated with a tethered cord and other complications. Spondylolisthesis may be present, particularly with hyperlordosis. (A common condition, hyperlordosis results from the imbalance of functioning flexors unopposed by the extensors, which have a higher innervation and may be absent.) Lordosis is never found at birth, but fixed flexion deformities of the hip and lumboperitoneal shunting have been associated with a significant incidence of hyperlordosis. This may be the result of muscle imbalance, particularly pertaining to the hips, or it may be caused by posterior scarring from other spinal surgery. The problem may require an anterior wedge resection or posterior fusion to prevent interference with ambulation.

Pelvis and hip

Paralysis at any level may lead to an imbalance of the extensors of the lower extremity, and dislocation of the hip occurs frequently in patients with spina bifida. The incidence increases as the level of the neurologic lesion ascends. Management has varied from ignoring the dislocation to aggressively treating it, but treatment is generally more aggressive in patients with the potential to ambulate and in those with strong quadriceps muscles. Efforts to reduce the hip in cases of spina bifida require some attempt at muscle balancing to prevent recurrence.

In the absence of hip extensors, because their innervation is lower than that of the hip flexors, a posterior-superior dislocation is anticipated. Acetabular dysplasia is routinely seen with disruption of the Shenton line and often with the failure of formation or asymmetry of the ossific nucleus. In addition to the iliopsoas, which has a tendency to cause a valgus deformity, the adductors may be present and innervated at approximately L3 or L4, causing windblown extremities. In fact, as these present very early, a potential for pelvic obliquity exists. In some cases, a pelvic osteotomy has been recommended to level the pelvis. Traditional indications for hip reduction include a potential ambulation with a strong quadriceps, a good range of motion of the hip, and a level pelvis.

Sharrard (1964) popularized an operation in which the iliopsoas was transferred through a defect created in the ilium, with the muscles balanced by a reattachment to the trochanter for abduction and extension forces. A progressive dislocation of the hip in a patient who has previously had a stable neurologic status should be investigated, specifically for a tethered cord. If a tethered cord is present, treatment following its release includes the creation of a Staheli-type acetabular shelf, with an external oblique transfer for muscle balancing; this technique has produced good results.

Generally, flexion deformities of the knee occur in patients with weak quadriceps, and only one third of patients with flexion contractures of more than 10° can maintain ambulatory status. These contractures should be braced when they progress past 10-20°, and a release procedure should be performed at 20-40°. Hyperextension or recurvatum deformity with limited flexion is associated with a poor prognosis for ambulation, especially when it prevents a normal alignment in a young child. The older child may require a quadricepsplasty or femoral osteotomy, particularly in cases of valgus alignment.

Foot and ankle

The flail foot customarily has no deformity and, for the purpose of function or gravity stress, may be braced to point out at the horizon. The bracing is done early, either in a parapodium or a standing frame, and, later, in association with other bracing as appropriate. When a varus deformity or equinovarus is noted, it customarily localizes to a neurologic level of L4. This actually is a clubfoot, which usually is subsequently resistant.

A talectomy may be appropriate in children aged 10 years or younger who have a resistant clubfoot. A triple arthrodesis may possibly be performed after that, and in some cases, calcaneocuboid excision or calcaneal osteotomy may be required.

The calcaneal valgus deformity, which customarily develops after the patient begins weightbearing, interferes with bracing. In some cases of skeletal maturity, a triple arthrodesis may be required. A calcaneal deformity customarily is localized to lower levels, such as L5 and S1. If untreated, it progresses to a bulky, prominent heel that is prone to ulceration. At the L4 level, the anterior tibialis is weak, so an anterior capsulotomy and bracing are appropriate. At the L5 and S1 levels, at muscle strength of grade III or better, posterior transfer of the anterior tibialis to the posteromedial calcaneus along with lengthening of the Achilles tendon and a solid AFO may be satisfactory.

A cavus deformity may be associated with a lower neurologic lesion. The lesion is sometimes at S2 and can produce intrinsic tightness, which may respond to a Steindler plantar fascial release from the heel or Dwyer calcaneal osteotomy. At maturity, a triple arthrodesis is very successful. The equinus deformity develops after birth, secondary to gravity. It customarily is treated by lengthening the Achilles tendon. Equinovalgus with either a pes valgus or vertical talus, which occurs in up to 10% of patients, requires talectomy. For older patients, extensor releases and osteotomy on the lengthening Achilles tendon may be appropriate.

Follow-up

Because muscle imbalance causes progressive, resistant deformities, the patient with spina bifida must frequently be evaluated by members of his or her support team. In this way, they can assess muscle groups, emphasize the need for balance to prevent deformities, and serially document changes that may result from tethered cord, hydrocephalus, or other associated complications (eg, seizure disorder).

Frequent review of spina bifida support systems, aggressive shunting of hydrocephalus, the cooperation and success of patients in physical therapy, and assessment of the status of patients' braces, crutches, or wheelchairs are necessary for maximizing function in a multidisciplinary setting. With supplementary physical and occupational therapy, many children who were born with spina bifida can participate in mainstream society, gaining both independence and success.

COMPLICATIONS

Section 8 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Patients with myelomeningocele can have several complications, of which fracture is very common. Twenty-two percent of patients have a significant fracture in their lifetime and may have a fracture associated with a significant surgical procedure, such as hip reduction or spine surgery. During the postoperative period, patients are not upright and have disuse osteoporosis complicating their already present osteopenia. Fracture may occur without pain and often is associated with an elevated temperature and redness, swelling, and warmth in the fracture area. An associated pressure sore sometimes occurs. In some cases, the sedimentation rate and white blood cell count are mildly elevated in reaction to the swelling. In other instances, radiographs reveal marked periosteal elevation and exuberant callus, which occurs because the fracture is adjacent to a Charcot joint. Osteomyelitis and septic arthritis are differential diagnoses.

Management includes inspection of the skin in cases of stable fracture, as well as possible immobilization using existing braces (locked on a 24-hour basis) or plaster immobilization. In some cases, open reduction and internal fixation are required for reasonable function. Patients who have had a major surgical procedure are best treated as soon as possible, because early treatment may diminish the fracture rate. A study of patients who underwent hip reduction revealed that placing the patient back in some form of cast or HKAFO brace in an upright position in the immediate postoperative period eliminated fracture; prior to the institution of this postoperative weightbearing, 22% of patients sustained fracture on follow-up.

Ulcers from bracing are prominent in the lower extremities, in the pelvis, and, particularly, over the bony prominences as a result of sitting. Carefully inspecting the skin on a routine basis is important because the area may be subjected to pressure for a couple of hours. The skin subsequently may be reddened, and although the patient may have no pain, the skin can develop significant full-thickness problems after only a brief period of neglect.

Infection is common, particularly with a neurogenic bladder. An increased risk exists with any operative procedure.

Retethering of the spinal cord frequently occurs and may benefit the patient urologically and orthopedically; any suspected change in muscle status, which must be serially monitored, or urologic status may be a sign of retethering.

Patients with spina bifida have an increased incidence of sensitivity to latex, which can cause anaphylactic reactions. Anecdotally, the author witnessed an unsuspected reaction during open reduction and internal fixation of a femoral fracture. Although the child undergoing the procedure had had prior operations without incident, upon dissection down to the fracture, anaphylaxis with complete arrest occurred when the author's gloved finger touched the bone. After resuscitation and glove change, the procedure was completed uneventfully. Risk factors for latex sensitivity, beyond having a myelomeningocele, include multiple operations, particularly in the first year of life. The most common source of latex exposure is balloons, followed by latex gloves. Treatment with latex-free materials has been shown to reduce the incidence of reactions; these materials may also diminish sensitization, and they can familiarize the staff with the allergy problem and with substances that may contain latex that would not

otherwise be suspected.

OUTCOME AND PROGNOSIS

Section 9 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Aggressive treatment with closure in the neonatal period leads to survival in most cases of spina bifida, and aggressive shunting of hydrocephalus can permit the retention of near-normal intelligence in the majority of patients. Prognosis in terms of ambulation generally is dependent on neurologic level and the strength of the quadriceps muscle. As long as flexion contractures and skeletal deformities are not severe, patients with no lower-extremity reflexes may, with determination and strong upper extremities, become ambulatory using bilateral Lofstrand or forearm crutches. Longevity may be dependent on renal function; careful, clean, intermittent catheterization; and compliance with a bowel and bladder regimen. Long-term survival into adulthood and advanced age is now common with aggressive treatment and an interdisciplinary clinical approach.

FUTURE AND CONTROVERSIES

Section 10 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Spina bifida is a neural tube defect that seems to be associated with folic acid levels during pregnancy. Further investigation has shown that folic acid supplementation during pregnancy may decrease the condition's incidence rates. However, the metabolism of folic acid appears to be abnormal in affected patients, suggesting that spina bifida may result from an inherited defect rather than a deficiency. High intake of folic acid may mask the anemia of vitamin B-12 deficiency and allow neurologic damage to progress untreated. Better understanding of the genetic factors involved in spina bifida could allow for its prevention.

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

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Article Last Updated: Jan 26, 2007