Pediatric Annals

Myelomeningocele and Its Problems

David H Bahnson, MD

Abstract

Today's myelomeningocele patient is a product, a challenge and a dilemma of modern medicine. Infants who previously would have died from complications of this condition now, with the aid of improved treatment, survive well into adulthood, and in so doing present the multidisciplinary team with a number of complex and challenging problems that must be solved to improve their quality of life. In the assessment of our present state of the art, a continuing question resurfaces. Should a child born with a life-threatening condition be treated aggressively, when often the best prospects for survival include multisystem handicaps for which there is no cure? Considerable controversy surrounds this sensitive question, a question which remains unanswered.

Although the birth of a child with myelomeningocele may be normal, the aftermath is a disaster. From the very first day of life, these children begin a course in life that will never be normal. Opportunities for the development of normal motor milestones will be hampered and the social environment will be awkward and unnatural. A child will draw into its future a seemingly endless association with a variety of doctors, nurses, therapists, social workers, orthotists and other care specialists. Parents of these children at the time of birth have little reason to suspect the immensity of the problems that lie ahead for them and their child. The most significant crippling aspect of myelomeningocele is the paraplegia associated with it. Although many other congenital abnormalities may be present and further compound the condition, the basic handicap is that of a fixed neurologic loss that does not progress. Unlike the adult paraplegic, however, the problem of the myelomeningocele is compounded by both physical and social growth. They are, in effect, "growing paraplegics" who must somehow adapt to the society around them.

As previously mentioned, many of these children in the past died of complications related to meningitis, ventriculitis, hydrocephalus, sepsis, renal failure and other causes. The survivors were often hospitalized with massive hydrocephalus and crippling deformities. With improved treatment techniques including antibiotics and early ventriculoperitoneal shunting, the population of surviving patients has increased dramatically, and they challenge both our ingenuity and our resources.

TERMINOLOGY

Spinal dysrhaphism is a broad term meaning literally "defective seam" and, according to Lichtenstein1 includes a variety of embryonic ectodermal, mesodermal and neurectodermal defects. Included in the category are some of the more subtle congenital defects such as diastematomyelia, dermal sinus, intradural lipoma, tethered cord and other closed lesions. Some forms of spinal dysrhaphism are not clinically obvious, and present only as subtle neurologic changes which may accompany growth.

Spina bifida is also a very broad term implying failure of fusion of the vertebral arches. It is subdivided into two main categories. Spina bifida aperta (open) includes the common myelomeningocele and, as the name implies, the defect communicates with the outside. Spina bifida occulta (covered) occurs when the neural arch has not fused, but skin and other soft tissues overlie the defect. In the human population, 5-10% may demonstrate spina bifida occulta, usually occurring at the L5 region.

Meningocele is a form of spina bifida in which the lesion contains a herniated sac covered by meninges but does not contain neural elements. They are less common than myelomeningocele and usually occur at the cervical spine. In myelomeningocele the herniated sac contains neural tissue usually consisting of distended nerve roots and often a portion of the spinal cord which is usually present as a neural plaque (Figures IA and B). Because of the distention and pressure on the neural elements, there is usually little or no function distal to the level of the lesion…

Today's myelomeningocele patient is a product, a challenge and a dilemma of modern medicine. Infants who previously would have died from complications of this condition now, with the aid of improved treatment, survive well into adulthood, and in so doing present the multidisciplinary team with a number of complex and challenging problems that must be solved to improve their quality of life. In the assessment of our present state of the art, a continuing question resurfaces. Should a child born with a life-threatening condition be treated aggressively, when often the best prospects for survival include multisystem handicaps for which there is no cure? Considerable controversy surrounds this sensitive question, a question which remains unanswered.

Although the birth of a child with myelomeningocele may be normal, the aftermath is a disaster. From the very first day of life, these children begin a course in life that will never be normal. Opportunities for the development of normal motor milestones will be hampered and the social environment will be awkward and unnatural. A child will draw into its future a seemingly endless association with a variety of doctors, nurses, therapists, social workers, orthotists and other care specialists. Parents of these children at the time of birth have little reason to suspect the immensity of the problems that lie ahead for them and their child. The most significant crippling aspect of myelomeningocele is the paraplegia associated with it. Although many other congenital abnormalities may be present and further compound the condition, the basic handicap is that of a fixed neurologic loss that does not progress. Unlike the adult paraplegic, however, the problem of the myelomeningocele is compounded by both physical and social growth. They are, in effect, "growing paraplegics" who must somehow adapt to the society around them.

As previously mentioned, many of these children in the past died of complications related to meningitis, ventriculitis, hydrocephalus, sepsis, renal failure and other causes. The survivors were often hospitalized with massive hydrocephalus and crippling deformities. With improved treatment techniques including antibiotics and early ventriculoperitoneal shunting, the population of surviving patients has increased dramatically, and they challenge both our ingenuity and our resources.

TERMINOLOGY

Spinal dysrhaphism is a broad term meaning literally "defective seam" and, according to Lichtenstein1 includes a variety of embryonic ectodermal, mesodermal and neurectodermal defects. Included in the category are some of the more subtle congenital defects such as diastematomyelia, dermal sinus, intradural lipoma, tethered cord and other closed lesions. Some forms of spinal dysrhaphism are not clinically obvious, and present only as subtle neurologic changes which may accompany growth.

Spina bifida is also a very broad term implying failure of fusion of the vertebral arches. It is subdivided into two main categories. Spina bifida aperta (open) includes the common myelomeningocele and, as the name implies, the defect communicates with the outside. Spina bifida occulta (covered) occurs when the neural arch has not fused, but skin and other soft tissues overlie the defect. In the human population, 5-10% may demonstrate spina bifida occulta, usually occurring at the L5 region.

Meningocele is a form of spina bifida in which the lesion contains a herniated sac covered by meninges but does not contain neural elements. They are less common than myelomeningocele and usually occur at the cervical spine. In myelomeningocele the herniated sac contains neural tissue usually consisting of distended nerve roots and often a portion of the spinal cord which is usually present as a neural plaque (Figures IA and B). Because of the distention and pressure on the neural elements, there is usually little or no function distal to the level of the lesion and is the basis for the paraplegia associated with this.

Rachischisis is technically synonymous with myelomeningocele but usually implies a more extensively involved defect in which there is complete absence of skin and sac so that uncovered neural and osseous elements are exposed.

Myelodysplasia indicates disease associated with the spinal cord. Clinical usage of this term places appropriate emphasis on the neurologic loss associated with a broad variety of spinal cord pathology.

EMBRYOLOGY

The mechanism of formation of the myelomeningocele defect is unknown. It is not known whether the neural tube fails to close or whether it initially forms and subsequently ruptures.2 Evidence does exist that the condition arises quite early, perhaps before the fetus is 30 days old,3 and that it may be influenced by a number of environmental as well as genetic factors, including geographic location, socioeconomic status and others.4"7 Even though there is a definite genetic influence, more than 90% of all pregnancies with neural tube defects occur in families with no preceding affected members.8

The condition is associated with other congenital abnormalities. Eighty percent or more of these children will have some degree of hydrocephalus. This is often associated with the Cleland-Arnold-Chiari malformation. Brain atrophy is usually not present at birth so that early ventriculoperitoneal shunting is effective in preventing progressive central nervous system deterioration due to the hydrocephalus. Many of these children shunted early will have normal intelligence. Other congenital defects include vertebral anomalies (hemivertebra, unilateral unsegmented bars, diastematomyelia) and anomalies of the kidney and urinary collecting system.

NATURAL HISTORY AND ETHICAL CONSIDERATIONS

The majority of patients with open spinal defects who are not treated at all will die within several months of life, the more severe involvement usually being fatal within hours of birth. Non-treatment is defined as the absence of all medicines including topical or systemic antibiotics, withholding of any surgical procedure and feeding orally by demand only. Many series support the contention that more than 90% of these patients (up to 100% in some series) will not survive if they are truly not treated.9"15 This does not include survival figures where partial treatment such as intravenous feeding or topical antibiotics have been instituted. These series are based on untreated individuals at all levels of involvement. Survivors in these series have tended to have lesser degrees of involvement, and many are reported as being continent without evidence of hydrocephalus. In short, the likelihood of a severely involved patient surviving completely without treatment is small, whereas lesser involvement may be compatible with life even when completely neglected.

Figure 1.(A) - Myelomeningocele in a newborn; (B) - Neural plaque.

Figure 1.(A) - Myelomeningocele in a newborn; (B) - Neural plaque.

Figure 2. (A,B) - Infant with myelomeningocele; (C1D) - Same patient several years later demonstrating ability to sit and stand in braces.

Figure 2. (A,B) - Infant with myelomeningocele; (C1D) - Same patient several years later demonstrating ability to sit and stand in braces.

These and similar data led Lorber16 in 1971 to review 524 unselected patients who were aggressively treated with available methods at that time. Based on his review, he concluded that: 1) overall survival was 41%; 2) only 7% of children treated were considered to have physical and mental capabilities consistent with self respect, independent earning capacity and eventual independence; 3) of the survivors, 66% had an IQ less than 80; 4) 31% were confined to wheelchairs; 5) selection criteria, which he advocated, would be useful to determine maximal effective use of resources in treating the population with this condition.

There are many drawbacks to any analysis such as that performed by Lorber partly because there are so many variables to be analyzed. Lorber, however, did point out a paradox which is still evident in any myelomeningocele clinic today. Aggressive and improved treatment does not lead to fewer handicapped children, but to more survivors, some with even greater handicaps. With this thought in mind, he formulated and advocated what he considered appropriate selection criteria at that time. These are as follows: 1) severe paraplegia (hip flexors and abductors or less); 2) gross enlargement of the head (2 cm above the 90th percentile); 3) kyphosis; and 4) associated gross congenital anomalies or major birth injuries. In short, he advocated that the severely involved infant should be allowed to die and that resources and efforts should be concentrated on improving the quality of life of the less severely involved.

In actual practice, at least in the United States, "selection" has not proved to be a practical solution to the problem of myelomeningocele. This is due to a number of moral and ethical considerations as well as some legal precedents. It is very difficult in today's medical and legal environment to completely withhold treatment, particularly from a child, with a life-threatening condition such as myelomeningocele. While it would seem appropriate to leave this decision up to the parents, even this concept has been rigorously challenged. In addition, most parents would not be expected to have the information and understanding available to them in the first 24 to 48 hours after birth when they would have to make a decision.

A word of caution is appropriate here. "Selection" should be thought of as an all or none phenomenon. Once it has been determined that the child should be treated, all available resources should then be utilized in that child's management from that point on. The fact that a given child "might not have been allowed to survive" should not govern our thinking or management at any time. The only possible exception to this might be when a true lifethreatening situation again existed. Otherwise, it is inappropriate to withhold treatment.

Perhaps the only satisfactory management of this disorder lies in the prevention of its occurrence. Amniocentesis for alpha fetal protein during the second trimester when positive has an extremely high correlation with neural tube defects. This is useful in determining the condition in utero but it is not a useful screening procedure. Recent techniques of obtaining serum alpha fetal protein determination during the 16th and 17th weeks of pregnancy could identify risk pregnancies in which amniocentesis would then be indicated.17 Therefore, this may be a useful clinical screening method of prenatal detection. It would provide some time for parental counseling and understanding of the condition, but it still ultimately carries the same ethical consideration with respect to termination of the pregnancy.

TREATMENT

General Principles

As mentioned previously, in the United States infants born with myelomeningocele will be treated by prompt closure of the defect, intravenous antibiotic therapy when appropriate and other supportive measures as indicated by the patient's condition. At this point, the die is cast and the patient is a survivor rather than a casualty of what has been referred to by Bunch as "the most complex treatable congenital anomaly of the central nervous system consistent with life."18 The patient begins his confrontation and adaptation to his multisystem handicaps. The ultimate goal in management of the myelomeningocele patient is achievement of independence and self respect. Ideally, then, the patient should obtain the ability to be mobile, whether independently or with assistive device including wheelchair, crutches and braces, etc., and the ability to interact comfortably with other members of society. Both of these aspects must be taken into account, and neither should overshadow the other. The patient who has spent most of his life in the hospital undergoing multiple operations and complications may end up a social cripple. On the other hand, a child with sound emotional development and self respect may be much more readily able to adjust to his physical handicap. The most rewarding survivors of this devastating condition have attained what has been referred to by Burr Curtis" as "social mobility," and this should be the ultimate goal of management.

Management of the myelodysplasia child is best handled in a multidisciplinary clinic. For reasons cited above, the whole child must be treated. At the same time, expansion of treatment methods to the present status necessitates subspecialty involvement at many levels. Treatment protocols need to be formulated which take into account the need to use the services of other subspecialty managements, and these should be designed to interfere with each other as little as possible. Several of the specialty considerations will be mentioned briefly.

The pediatrician usually initiates the general management of the case and helps serve as a coordinator of the other disciplines in the total treatment plan. He very often becomes the single most important figure in the eyes of the parents as a problem solver for a variety of situations. He frequently will be involved in the early decision of treatment versus nontreatment and may be called upon to participate in the difficult task of educating the parents as to what lies ahead. His role in establishing reasonable parental expectations and understanding is essential. For the pediatrician, a knowledge of what the other specialties are doing, the pitfalls they may encounter, and the danger signs and symptoms necessitating further referral and work-up must be understood. Very often the pediatrician will serve as a clinical coordinator when the child's care is centered in a multidisciplinary clinic.

The neurosurgeon is usually called upon early in the treatment to evaluate the degree of neurologic involvement, the level of involvement and the presence or absence of hydrocephalus. Once a treatment plan has been undertaken, prompt closure of the spinal defect and coverage with muscle, fascia and skin, provides the best resistance to infection, although it probably does not improve neurologic function. Delaying closure beyond 48 hours of an unsterile sac results in a high incidence of meningitis. Many of these children will require shunting procedures and subsequent evaluation for shunt malfunction or delayed hydrocephalus. In our clinic, the technique of closure using flank relaxing incisions has provided immediate coverage over the spinal defect and provided considerable durability in this region.20 Other neurosurgical conditions such as tethered cord are not infrequently seen in the myelomeningocele clinic.

The urologist must manage all of the complications associated with neurogenic bladder. Efforts are directed toward preservation of renal function and a sterile urinary tract, as well as providing a socially acceptable means of urine. Because of the long-term problems with reflux secondary both to the Crede maneuver and some of the urinary diversion procedures, the most common method used in our clinic is intermittent self catheterization. Congenital malformations of the urinary tract may further complicate the management problems. Renal failure as a cause of death in these individuals is a much less common occurrence with improved urologie management.

Any clinic specializing in management of the myelodysplasia child will draw heavily on resources provided by ancillary services such as those of the physical therapist, occupational therapist, orthotist, social worker, nurse specialist and many others. These people provide an essential service directly to the patients, but also are often capable of providing to the physician information that is otherwise unavailable or difficult to extract. For total care of the spina bifida child, a team approach is mandatory.

ORTHOPEDIC MANAGEMENT

The main goal of the orthopedist is to minimize the myelomeningocele child's inability to meet normal motor milestones necessary to provide an environment consistent with his intellectual, emotional and social development. Mobility is a key factor in obtaining this type of environment, and therefore the orthopedist must maximize the child's potential to ambulate at an appropriate time, and if ambulation is not possible, provide some reasonable means for the child to move about. It must be recognized that many children who are able to ambulate ultimately will lose this ability in their teens or shortly thereafter. This should not be an excuse to abandon efforts at an early stage.

For purposes of analyzing functional levels of ambulation, the classification provided by Hofer and others is most often used.21 This provided four functional categories: 1) community ambulators - able to walk indoors or outdoors for most activities, wheelchair used only for long trips out of the vicinity; 2) household ambulators - able to walk indoors and transfer, wheelchair for use in the community and often for indoor activities; 3) non-functional ambulators - can walk as a part of therapy sessions but uses a wheelchair for most transportation needs; 4) non-ambulators - wheelchair bound. Structural deficiencies such as scoliosis, dislocated hips, joint contractures, etc., may interfere with the patient's ability to attain his potential functional level. Many of these problems can be corrected or adaptations can be made to improve the level of function.

Although many factors such as intelligence, motivation, home environment, etc., are involved, the most consistent and most significant factor in determining ultimate functional level is the level of neurologic lesion itself - that is, the root level or levels at which useful neurologic function is disrupted. Treatment methods, therefore, must account for differences in level of function. Dislocated hips, for example, in the thoracic level paraplegic may be better left untreated. The same condition in a low lumbar level patient may have markedly adverse effects unless treated aggressively. Some principles pertaining to this will be discussed later. It is very useful, when planning the management protocol, to take into account the level of neurologic disruption. Table 1 shows the motor innervation correlating to specific root level of involvement. It becomes apparent from this that a thoracic level paraplegia is associated with complete paralysis of the lower extremities while as each successive lumbar root is innervated, additional motor function is obtained. For purposes of convenience, the myelomeningocele child may be thought of as falling into one of four major motor level groups. This would include thoracic level (T 12 and above), upper lumbar level (L 1-2-3), lower lumbar level (L4-5) and sacral level involvement (S 1 and below). Each group of individuals tends to have "characteristic" problems associated with their level of involvement and each group would have a predicted level of independent function.

There are several important general principles and concepts which must be kept in mind at all times. Failure to recognize and adhere to these principles may be associated with preventable complications of treatment.

* The neurologic level is usually determined by the lowest functioning motor root level. This delineation is not absolute by any means, and "spotty" innervation of lower levels is quite common. The presence of activity at a motor level does not mean normal strength for that muscle group, so that the lowest functioning motor level should normally include only those muscles with good to normal voluntary strength, even though others may cause deformity.

* Sensory levels do not seem to be reliable when predicting corresponding motor behavior, but they are extremely important in bracing considerations.

* Neurologic "level" is seldom 100% symmetrical, and variations of one or two root levels (or more) between left and right sides is not at all uncommon.

* Hydrocephalus, meningitis, neonatal hypoxia and spinal cord (versus root) compression of higher levels and other upper motor neuronal conditions may introduce an element of spasticity, with corresponding propensity of a particular muscle group to exert a more substantial deforming force.

* Neurogenic deformity passes predictably through three phases. These are: 1) passively correctable deformity without contraction; 2) fixed deformity with soft tissue contracture but no bony change; 3) fixed deformity with, secondary bony change. The implications of this are obvious. The earlier such deformities are corrected or preferably prevented, the easier it is to maintain normal anatomical relationships with a minimal amount of surgery. This usually implies early surgical intervention in the presence of predictable progressive deformity.

Table

TABLE 1ROOT INNERVATION OF MUSCLES OF THE LOWER LIMB

TABLE 1

ROOT INNERVATION OF MUSCLES OF THE LOWER LIMB

* A joint deformity caused by neurologic imbalance cannot be permanently corrected or prevented without altering the muscle imbalance in some way to achieve balance of power across the joint. This basic concept cannot be overemphasized. Soft tissue or bony procedures that attempt to correct neurogenic deformity without correcting or altering muscle forces are likely to fail. Serial casting, stretching exercise, and even surgical measures done in the face of neurologic imbalance should be viewed only as a temporary form of treatment.

Figure 3. (A1B) - Lumbar kyphosis associated with severe thoracic lordosis.

Figure 3. (A1B) - Lumbar kyphosis associated with severe thoracic lordosis.

* Assessment of specific neurologic level during infancy may be quite difficult, and often the exact level of involvement is not firmly established until the child is old enough to cooperate with manual muscle testing routine.

SPECIFIC TREATMENT CONSIDERATIONS

The following presents a thumbnail sketch of the "typical" problems to be anticipated corresponding to the level of involvement.

Thoracic Level

These represent the most severely involved children and as pointed out earlier present with adverse criteria for selection as defined by Lorber. They require full bracing to include pelvic support for standing and for ambulation with swing-to gait. Most children will require some form of spinal orthosis as well. Even with present treatment, virtually all of these children ultimately will lose ambulatory function in their teens or sooner.

At this level, 100% of the patients will develop some degree of spinal deformity manifested by kyphosis, scoliosis, thoracic lordosis, and varying combinations of all of these.22 The most serious spinal deformity affecting these children is the combination of a fixed lumbar kyphosis associated with a progressive thoracic lordosis which itself may cause cardiopulmonary compromise. An example of this is illustrated (Figure 3). A one-stage excision of the defective spinal cord and its contents as well as several vertebral bodies, combined with the Harrington posterior compression device, was utilized to achieve a more physiologic spine and arrest the progression of the potentially fatal thoracic lordosis. Spinal deformities in the myelodysplastic child can be classified as either congenital or developmental. Developmental curves occur in the face of inadequate muscular support for the spine in the absence of other congenital anomalies except for the myelomeningocele defect. Congenital spinal deformities occur from additional malformations of the spine which cause asymmetry of growth. Both of these are generally progressive, but the congenital form requires earlier surgical intervention and is less amenable to bracing.

Spine fusion is generally performed to include the sacrum, and subsequently there is loss of normal spinopelvic motion. For this reason, it is essential to preserve as much motion at the hips as possible, to allow the child to be able to both sit and stand.

The hips of the thoracic level paraplegic are flaccid and gravity is the main deforming force, so that hips tend to assume a position of abduction, external rotation and some degree of flexion. A hip in the reduced position would be anticipated to remain that way because of the absence of deforming forces.

Figure 3. (C1D) - Post-operative correction obtained from vertebral excision and compression rod fixation.

Figure 3. (C1D) - Post-operative correction obtained from vertebral excision and compression rod fixation.

When bilateral hip dislocations are present in the thoracic level myelomeningocele child, surgical attempts to reduce these hips would be considered unwise. The dislocated hip tends to remain pain free and have a range of motion consistent with both sitting and standing. Attempts at surgical procedures may cause significant loss of motion in the hip, and can result in serious disability with respect to pressure sores, etc.

The knee is also flaccid and range of motion can usually be maintained by a passive physical therapy program of flexion and extension of the knee. Again, this range of motion is helpful to allow flexion at the drop lock joint of the knee so that sitting and standing can both be achieved. Angular deformities of more than 20° present significant difficulties in fitting of braces and may require osteotomy to correct. Postoperative pathologic fractures are not uncommon, but these can be minimized by early weight bearing in the postoperative cast or braces.

The foot and ankle will often be flaccid with no protective sensation present (Figure 4). A plantar grade foot capable of bracing without breakdown of skin is a desirable result and the goal of treatment. When deformities are present early cast correction with meticulous care to avoid damage to the insensate skin is the treatment of choice, and recurrent deformity based on neuromuscular imbalance is not predicted. In the rigid and more severe deformities, soft tissue release may be necessary, but frequently removal of the talus provides satisfactory long term correction.23 Recurrent deformity in flaccid feet should make one suspicious of neuromuscular imbalance and not infrequently this will be of a reflex arc non-voluntary type of involvement. Also, one should be alert to the presence of paralytic vertical talus in the myelomeningocele population.24

Upper Lumbar Level

This neurologic level is characterized by the presence of strong hip flexors and in mid-lumbar levels by hip adductors and some knee extensors. Ultimate ambulatory ability is more variable and less predictable than either the thoracic or sacral level. The knees and feet must both be braced usually with pelvic attachment to achieve standing ability and control rotation of the hips.

There is a relatively high propensity for spinal deformity (Figure 5), although it may be more gradual or less severe than in the thoracic level. The iliopsoas muscle, in addition to producing the deforming force at the hips has the effect of producing or exaggerating lumbar lordosis. As in the thoracic level, spine fusion to the sacrum may be required, reducing the mobility and flexion /extension at the pelvis necessary for sitting.

At the high level lesion, the iliopsoas and sartorius combine to provide flexion and external rotation of the hips, but the tendency to dislocate is not nearly as great as in lower level where adductors are strong. Pelvic obliquity may play a major role in dislocation with the hip dislocating on the "high" side sometimes despite aggressive efforts to keep it located. The iliopsoas muscle may be resected or transferred to the anterior capsule.

Abduction splinting may be started early, with avoidance of adduction contractures of either hip. Release of the hip flexors and adductors may be performed through a medial approach before the age of 12 to 18 months if this is necessary.

Figure 4. Equinovarus feet in a thoracic level myelodysplastic patient.

Figure 4. Equinovarus feet in a thoracic level myelodysplastic patient.

Figure 5. Spinal deformity and its effect on sitting.

Figure 5. Spinal deformity and its effect on sitting.

Weak knee extension may be present but can be offset by functioning sartorius and gracilis unless the sartorius becomes a preverted extensor by displacement of the axis anterior to the femoral condyle. Passive stretching of the knee to achieve a 90° arc of motion usually allows for sufficient range to permit bracing. Surgical measures at this level include sartorius release, quadriceps lengthening (VY-plasty), femoral osteotomy or iliotibial tract resection.

At the upper lumbar level there are still no functional motors in the foot and the treatment is similar to that discussed at the thoracic level.

Lower Lumbar Level

The presence of voluntary functional quadriceps "or better" defines this group. A recent review has implicated the importance of quadriceps function for realistic longterm independent ambulation.23 Frequently, short leg braces or thermoplastic AFO (ankle foot orthosis) are sufficient to provide full ambulatory potential, often without crutches. Neurogenic hip instability is common, and its treatment is essential to provide maximal overall function.

Developmental spinal deformities are considerably less common than in the thoracic or upper lumbar levels, but the spine needs to be evaluated and followed closely. No specific deformity is unique to this level of involvement. Approximately 60% of the L4 level patients and 25% of the L5 level patients will show evidence of some spinal deformity."6

The L4 lesion has the highest propensity for hip dislocation. As further levels are innervated, hip abductors (partial L5) and hip extensors (SI) make dislocation less likely as the hip is more evenly balanced. These hips are usually located at birth and develop neurogenic dislocation with time. When adductors and flexors are strong (this will usually be associated with active quadriceps in the presence of anterior tibial musculature in the pure L4 lesion), the hip will likely dislocate despite any nonoperative method to reduce it or any operative method in which muscular imbalance is not corrected in some manner.

Figure 6. Heel varus (on right foot) may be a subtle finding indicative of occult neurologic loss.

Figure 6. Heel varus (on right foot) may be a subtle finding indicative of occult neurologic loss.

Treatment at this level, therefore, requires that the hip be located, and that the musculature about the hip be balanced. Methods of achieving this represent a difficult and somewhat controversial topic and will not be dealt with extensively here. Suffice it to say that at this level, aggressive surgical treatment of the hip is probably warranted despite a rather high reported complication rate.

As alluded to previously, the presence of strong quadriceps musculature at this level represents a distinct asset to the patient in achieving ambulatory ability. Generally, there is at least some knee flexion, but sometimes hyperextension deformity will develop. This may be treated by VY lengthening procedure and sometimes requires open reduction of the knee. Flexion contractures should be avoided and when they occur, treated aggressively since they represent a severe disability with respect to bracing and ambulation.

At the low lumbar level, there is considerable variation of both intrinsic and extrinsic foot musculature because of the narrow band of overlap at each root level. Carefully applied corrective plaster casts in the first few days of life will be successful in correcting the deformity, but once corrected the feet should be watched closely for recurrence. A common problem seen at this level is the calcaneous deformity produced by functioning dorsiflexors (especially anterior tibial) in the absence of plantar flexors (especially gastrocnemius). The useful procedure to correct this problem and prevent deformity at an early age is transfer of the anterior tibial tendon through the interosseous membrane to the os calcis.26 This takes a significant deforming force and transfers at least some of its power into a corrective force.

Sacral Level

These patients should be anticipated to obtain completely independent community ambulation, and they usually do not require lower extremity or spine orthoses. The majority of the management revolves around the urologie problems and care of the feet.

Significant spinal deformity is uncommon in this region and has been estimated to be only approximately 5%. Other forms of spinal dysrhaphism such as tethered cord and diastematomyelia should be watched for closely.

At the sacral neurologic level, the hips are nearly completely balanced, although there may be some weakness of hip extension. Neurogenic tendency to dislocation therefore is quite low and in most respects the hips behave in a manner similar to those that are normally innervated.

The musculature about the knee in the sacral level paraplegic is also balanced and anticipation of paralytic deformity is low. Bracing of the knee to improve stability is seldom necessary.

At the sacral level of involvement, the care of the feet assumes prime importance. Particularly due to lack of thé more proximal deformities or paralysis, the child may be considerably more active in terms of weight bearing and ambulation. In addition, these children may be expected to retain their ability to ambulate, so that early surgical procedures affecting the resiliency of their foot should not be undertaken lightly. Perhaps the most important factor to consider is the sensory status of the sole of the foot. In the absence of protective sensation, foot deformities affecting weight-bearing relationship of the forefoot and hindfoot are considerably more likely to cause skin ulcerations and secondary problems. Each foot deformity, of course, must be individually analyzed with respect to presence or absence of both intrinsic and extrinsic motor function. Every attempt should be made to provide a plantigrade foot that is flexible and able to withstand normal weight- bearing stresses, and balanced so as to obviate progressive deformity. Tendon transfers should be performed when indicated, prior to the progression to the point of fixed deformity. This is usually sometime between the ages of one and two. Similarly, soft tissue releases may be helpful at an early age.

If the deformity is allowed to persist to the point that it becomes fixed, then the surgeon may have to resort to more extensive bony procedures, such as arthrodesis of one or more joints. This significantly detracts from the resiliency of the foot and thus reduces its ability to provide functional, evenly distributed weight bearing. A common deformity seen in low level myelodysplasia patients is that of a cavovarus foot with claw toes. Heel varus should be looked for carefully (Figure 6). Various forms of surgical treatment are available for foot deformity including soft tissue releases of plantar structures or osteotomy of the calcaneous to correct the varus heel. A separate procedure is usually required for the claw deformity and may include transfer of flexors into extensors, extensor tendon resections to the metatarsal necks, tenodesis of the great toe as advocated by Sharrard or, when the deformity is fixed, interphalangeal fusion.

Fractures

Lower extremity fractures are common in the myelomeningocele population and they are especially likely to result after immobilization following surgical procedures. Therefore, one of the effective forms of treatment of fractures is prevention and this may be accomplished by carefui planning of the surgica) procedures to avoid excessive immobilization. In addition, weight bearing while in the postoperative cast has a substantial benefit on prevention of disuse osteopenia that may accompany prolonged nonweight bearing and nonactivity. When fractures do occur, they may be present only as swelling, redness and warmth at the area of the fracture site without history of injury or significant degree of pain, and they may often be misdiagnosed as infection. Fever, swelling, erythema and heat about a lower extremity in a myelodysplastic child should be considered to be a fracture until radiographically proven otherwise.

Stable and undisplaced fractures may be treated by immobilization in existing braces. When this regimen is utilized, the braces should be worn 24 hours per day (except to monitor skin care) with the joints locked until swelling has disappeared. Weight bearing should be resumed as early as possible.

Unstable fractures must be reduced and immobilized in plaster, again, with attempts at early weight bearing when this is feasible. Fracture healing time is not prolonged in the myelodysplastic patient.

Finally, recurrent fractures of the same extremity frequently represent a vicious cycle caused by repeated immobilization to treat fractures caused by immobilization initially. In this event, consideration should be given to intra-medullary rodding of the extremity to allow earlier functional weight bearing.

SUMMARY

The myelodysplastic child presents the orthopedist, as well as other specialists with a challenging complexity of problems which frequently tax our therapeutic resources. A team approach is essential and yet each child's problems must be individualized. Realistic goals must be established. With appropriate care, these children's lives may be substantially improved.

REFERENCES

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2. Bunch WK: Myelomeningocele: General concepts. AAOS Instruct Course Lect 25:61, 1976,

3. Emery JL. Lendon RG: Neurospinal dysrhaphism syndrome, in; AAOS Symposium on Myelomeningocele, St. Louis, Mosby. 1972.

4. Lawrence KM: The recurrence risk in spina bifida cystica and anencephaly. Dev Med Child Neurol (suppl) 20:23, 1969.

5. Naggan L, MacMahon B: Ethnic differences in the prevalence of anencephaly and spina bifida. N £ngl J Med 227: 1 1 19/ 1967.

6. Ren wick JH: Potato babies. Lancet 2:336. 1972.

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8. Haddow JE, Macri J M : Prenatal screening for neural tube defects. JA MA 242:515, 1979.

9. Lorber J; Results of treatment of myelomeningocele. Dev Med Child Neurol 13:279, 1971.

10. Hide DW, Williams HP, Ellis HL: The outlook for the child with a myelomeningocele for whom early surgery was considered inadvisable. Dev Med Child Neurol 14:304. 1972.

11. Knox EG: Spina bifida - Birmingham. Dev Med Child Neurol 13:14, 1967.

12. Lawrence KM: The survival of untreated spina bifida cystica. Dev Med Child Neurol (suppl) 11:10. 1966.

13. Lawrence KM: The recurrence risk in spina bifida cystica and anencephaly. Dev Med Child Neurol (suppl) 20:23. 1969.

14. Lorber J: Incidence and epidemiology of myelomeningocele. Clin Orthop 45:81. 1966.

15. Lorber J: Selective treatment of myelomeningocele: To treat or not to treat. Pediatrics 53:307. 1974.

16. Lorber J: Results of treatment of myelomeningocele. Dev Med Child Neurol 13:279. 1971.

17. Haddow JE, Macri JM: Prenatal screening for neural tube defects. JAMA 242:515. 1979.

18. Bunch WK: Myelomeningocele: General concepts. AA OS Instruct Course Lev 25:61, 1976.

19. AAOS Symposium on Myelomeningocele, Hartford, Conn, Nov, 1980.

20. Habal MB, Vries JK: Tension free closure of large myelomeningocele defects Surg Neurol 8:177. 1977.

21. Hoffer MM, Feiwell E. Perry R, et al: Functional ambulation in patients with myelomeningocele. J BoneJoim Surg 55?:)$7, J973.

22. Winter RB: Myelomeningocele in scoliosis and other spinal deformities, in: Moe IH, Winter RB, Bradford DS, Lonsten JB, (eds) Philadelphia, Saunders, pp 239-287, 1978.

23. Menelaus MB: Talectomy for equinovarus deformity in arthrogryposis and spina bifida. J Bone Joint Surg 53B:468, 1971.

24. Drcnnan JC. Sharrard WJW: The pathological anatomy of convex pes valgus. J Bone Joint Surg 53B:455. 1971.

25. Huff Cw. Ramsey PL: Myelomeningocele: The influence of the quadriceps and hip abduction muscles on ambulatory function and stability of the hip. J Bone Joint Surg 60A:432. 1978.

26. Winter RB: Myelomeningocele in scoliosis and other spinal deformities, in Moe JH, Wimer RB. Bradford DS. Lonsten JB, (eds) Philadelphia, Saunders, pp 239-287. 1978.

27. Peabody CW: Tendon transposition: An end result study, J Bone Joint Surg 20:193. 1938.

TABLE 1

ROOT INNERVATION OF MUSCLES OF THE LOWER LIMB

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