Connolly, Barbara H. EdD, PT; Kasser, Richard J. PhD, PT
A young child with a hemimeningomyelocele at the level of T7 through T9 vertebrae was referred to an early intervention program at two and a half months of age. In reviewing her medical records, it was noticed that different terms were used interchangeably to describe her condition, and hemimeningomyelocele was not one of them. Eventually, a diagnosis of hemimeningomyelocele was made on the basis of the child's progress in gross motor function. Our confusion over the use of various terms prompted us to present this case report, which not only describes the development of a young child with spina bifida and an accompanying split cord malformation but also clarifies the terminology of split cord malformations for the pediatric physical therapist.
Duckworth et al 1 first described the relatively rare condition of a combination split cord malformation and a meningomyelocele in 1968. This combination was appropriately designated hemimeningomyelocele because only one hemicord contributed to the myelomeningocele. Individuals with this combination usually have one normally functioning lower extremity with the other strikingly impaired. Normal bladder function is usually retained. 1,2 Duckworth et al 1 found that only about two to three percent of individuals with spina bifida have a hemimeningomyelocele, but split cord malformations may occur in as many as 50% of typical spina bifida cases with both hemicords protruding in the meningomyelocele. Pang et al 3 observed that most cases of hemimeningomyelocele are associated with split cord malformations in which the hemicords are housed in their own dural sac with a rigid osseocartilaginous median septum.
The child's medical records included the terms diplomyelia and diastematomyelia, used interchangeably to describe the child's condition. Strictly speaking these terms have different meanings. Diplomyelia (Greek; diplous = double) is a term used to describe two complete cords housed in a single dural sac. Diastematomyelia (Greek; diastema = cleft) is reserved for two hemicords housed in separate dural sacs with a midline bony spur between the two sacs. 4 James and Lassman 5 in 1964 suggested simplifying the identification by distinguishing between the two forms of split cord by considering only the presence of single or separate dural tubes.
Pang et al 3 more recently proposed that all spinal cord duplications be designated as split cord malformations and that criteria that would allow diagnosis using radiographs be used. Their criteria for split cord malformation type I (SCM I) are two hemicords, each contained within its own dural sheath, separated by a ridged osseocartilaginous median septum. Split cord malformation type II (SCM II) would be reserved for cases in which two hemicords are housed in a single dural sheath with a nonrigid fibrous median septum. These authors stated that this terminology is more appropriate because both conditions, in their view, are the result of a common embryogenic mechanism and hemicords are the rule, whereas adopting completely duplicated cords as a criterion is inappropriate because these are extremely rare. Furthermore, distinguishing hemicords from completely duplicated cords is difficult if not impossible using radiographs. We think using SCM I and SCM II terminology is the most useful.
Severe scoliosis at birth is the rule in most cases of hemimeningomyelocele. Maguire et al, 2 in a study of 10 children with hemimeningomyelocele, found scoliosis in 100% of the children. Possible explanations include asymmetrical innervation and/or bony abnormalities of the vertebrae. Children with spina bifida do not usually have obvious scoliosis at birth; however, approximately 50% of these children will develop scoliosis. 6 Children with hemimeningomyelocele may experience a progressive lumbar scoliosis due to the asymmetric growth of the anomalous vertebrae. The resulting deformity, due to the presence of anomalies at the lumbosacral junction, includes lateral deviation of the torso and pelvic obliquity. The pelvic obliquity results in elevation of the pelvis on the side of the deficient vertebral development. This pelvic elevation coupled with a potentially shortened leg on the side of the neural tube defect results in a large discrepancy in leg length.
An additional problem that occurs with SCM is tethering of the spinal cord. SCM I may cause tethering lesions because of the transfixation of the cord by the rigid meningo-osseous septum. 3 However, all those with SCM II have tethering lesions by virtue of the attachment of the hemicords to the median fibrous septum that inserts firmly into the dural sac. Tethering of the spinal cord is usually symptomatic and usually comes to medical attention in childhood as the symptoms become more pronounced. Symptoms may include pain, gait abnormalities, skeletal deformities (such as lumbosacral kyphosis), sphincter disturbances, and trophic ulcers. 7 Treatment consists of surgical release of the tether. Improvement in pain and sensorimotor function has been noted in approximately 80% of patients. 7
In the past, orthopedic treatment of children with hemimeningomyelocele has been directed at both the spinal deformity and the leg-length discrepancy. The use of shoe lifts are advocated for the leg-length discrepancy. However, the rigidity of the spinal deformity prevents treatment by cast or fusion correction. The use of a wedge resection has been successful in achieving adequate compensation of the spine according to Maguire et al. 2
The following is a case description of the development and treatment of a young child with a hemimeningomyelocele at T7 through T9 vertebrae. The child was followed from two and a half months to seven years of age.
The child was delivered after an uneventful pregnancy. The mother and father were both in good health, and the mother denied any exposure to chemicals, radiation, or other teratogens during her pregnancy. The mother's prenatal screening was negative, and she denied any rashes, hypertension, edema, or diabetes. According to the mother, fetal movements began during the third month and continued throughout the pregnancy. She noted the same degree of movement with this pregnancy as with her previous pregnancy. The length of the pregnancy was 39 weeks by dates. The child was delivered cesarean because of poor heart beat-to-beat variability. According to the medical records, the child was cyanotic at birth but did not require intubation. Apgar scores were four and eight at one and five minutes, respectively. Birth weight was seven pounds, 14 ounces; birth length was 47.5 centimeters; and head circumference was 34 centimeters. A meningomyelocele in the thoracolumbar region, less than seven centimeters in diameter, and two sacs or skin defects were noted at birth. The defect that was left of midline measured three by two centimeters and was covered by a meningeal sac. The other defect, located right of midline, measured two by one centimeters and was open. The patient exhibited spontaneous movement in both lower extremities and random movements in response to tactile and painful stimuli.
Additional analyses of the spinal defects were performed when the patient was less than one day of age. Radiographic studies, including a computerized tomography scan of the thoracolumbar spine, revealed a complex spina bifida with possible rudimentary formation of a duplicate spinal cord. A magnetic resonance image of the spine revealed multiple bony anomalies and a thoracic hemimeningomyelocele at the level of T7, T8, and T9 vertebrae. The bony anomalies included hemivertebrae and butterfly-shaped vertebrae. The meningomyelocele contained cerebrospinal fluid, meninges, and neural tissue. The cord was separated into two distinct elements that began at approximately the first thoracic vertebra and extended through the remaining portion of the cord. An ultrasound image of the head also was obtained, and an Arnold-Chiari type II malformation and mild ventriculomegaly were revealed.
The meningomyelocele was surgically closed at five days of age. The procedure was tolerated well, and postoperatively, the patient moved each leg individually in response to tactile and painful stimuli. At 15 days of age, the patient underwent ventriculoperitoneal shunting because of progressive ventricular enlargement. She was discharged at two and a half weeks of age but was rehospitalized at five weeks of age for one week because of sepsis. Although she had been referred to physical therapy before that hospitalization, the mother did not wish to start physical therapy until the infant's full course of antibiotics was completed.
Physical Therapy Examination
The patient was first seen in physical therapy at 10 weeks of age. At that time, the patient was noted to have full active movement of the right lower extremity. A gross manual muscle test of the left lower extremity revealed fair quadriceps, poor anterior tibialis, and trace plantar flexor strength. During spontaneous kicking, full right knee extension was achieved. Responses to tactile or painful stimuli to the left extremity were brisk except in the saddle area. A plantar grasp response was noted in the right foot but not in the left. A flexor withdrawal response could be elicited on the right leg but not on the left leg.
Right thoracolumbar scoliosis was present, with the left hip held higher than the right hip when the patient was placed supine. The scoliosis was flexible, but full lateral flexion on the right side could not be achieved in side-lying. Otherwise, full passive range of motion was obtained for all joint motions of the upper and lower extremities.
The patient was alert and responsive during the examination. A spontaneous smile was noted several times in response to the therapist and to the mother. In the supine position, the infant was able to track an object visually both across midline and vertically. She was able to hold her head in midline without difficulty and could visually fixate on a face or toy. She did not bring her hands to midline but was able to momentarily hold a rattle placed in either hand. In the prone position, she was able to lift her head to 45 degrees when placed over a small towel roll. Without the towel roll, she was content to maintain her head in contact with the support surface. While in a prone position, she attempted to kick her right leg but not her left leg. She tolerated lying on her right side but became irritable when placed on her left side. Sitting and standing were not attempted because of the physician's instructions to delay upright positioning until she was three months old.
Developmentally the patient was functioning at an eight-week level in her gross motor skills as measured by the Peabody Developmental Motor Scales (PDMS) and at the fifth percentile for age according to the Alberta Infant Motor Scales. Both scales were used to determine both developmental age and her abilities as compared with other eight-week-old infants. However, at this young age, her developmental activities involved primarily head righting and upper trunk movements. She was not tested in sitting or in standing.
Intervention and Outcomes
Initial goals set jointly by the parents and the therapist for the child after the evaluation included 1) pushing up onto extended arms in prone, 2) rolling prone to supine, 3) bringing hands to midline in supine and supported sitting, and 4) sitting with minimal support. Following the procedures used in the rural early intervention program in which she was enrolled, a home treatment program was developed by the physical therapist and demonstrated to the parents. Because of the presence of the thoracolumbar scoliosis, positioning was of primary importance in the home program developed for the infant. The parents were shown 1) how to position the child in side-lying; 2) how to change the child's positions during the day to stimulate head turning to the left and to the right; 3) how to perform passive range of motion activities for the lower extremities; 4) how to stimulate active movements in the lower extremities through the use of sensory stimulation (tactile and proprioceptive); and 5) how to stimulate head control through vestibular stimulation in prone, supine, and side-lying. 8 The patient was seen by the physical therapist every six weeks while on the home program. At each visit she was reassessed using the PDMS, and her home program was revised as needed.
The patient demonstrated recovery of motor and sensory function over time. At four months, she responded to tactile stimuli applied to the bottom of the left foot by dorsiflexing. The mother reported that she had been following the home program and that the child had begun to spontaneously move her left leg. New skills observed at four months of age included bringing hands to midline, holding objects in both hands, lifting the head to 60 degrees in prone without the towel roll (90 degrees with the towel roll), and rolling prone to supine. The child was able to prop on her forearms when placed but experienced difficulty in bringing her arms forward by herself to prop. The child was noted to kick her left leg when in supine and in prone with the quadriceps, anterior tibialis, and triceps surae all active during the kicking sequences. She was able to hold her head erect when held in supported sitting, and when supported at the chest, she was able to bring her head back to midline if tilted 30 degrees in any direction. Her gross motor skill level had progressed to the 16-weeks level at this time. A revised home program was developed for her with an emphasis on upright sitting (supported and unsupported sitting) and supported standing activities.
By seven and a half months, the mother reported that the child was having difficulty in separating from the parents and was beginning to recognize “strangers.” Testing at this time by the early intervention specialist revealed no delays in language or cognition in the child. New gross motor skills included rolling from supine to side-lying, sitting while propping on extended arms for up to five minutes, and pushing up to extended arms in prone. During supported sitting, she was observed to lean to the right side when she did not use her arms for support. According to her most recent radiographs, her scoliosis had increased five degrees since she was four and a half months of age, and this increase was thought to be influencing her posture during sitting. The child was observed to kick both legs in supine (right more than left) and to reach for her knees using her hands. She also participated in exploration of her upper legs with her hands. Her new skill level was assessed to be at the 24-weeks level. New activities added to her home therapy program included coming to sitting on support surfaces, rocking on hands and knees, and supported standing using a prone stander. The child's goals were reassessed at this time, and new goals were established with the parents. The new goals included standing and walking using a posterior control walker.
By nine and a half months of age, an increase in the patient's scoliosis, a subluxed left hip, and a leg-length discrepancy of one inch between the right and left legs (right leg shorter) were noted by the patient's orthopedist. However, the child was able to sit erect without support and used her hands for purposeful play. She tolerated a quadruped position when placed and attempted to rock back and forth on her own. In supported standing, she bore most of her weight on the right leg and resisted bearing weight on the left leg. Her home program was revised to include more time bearing weight on the left leg during quadruped and standing. However, she also was referred for reevaluation of the left hip by the orthopedist because subluxation of the hip had been diagnosed when she was seven months old. The orthopedist determined that no surgery or precautions for the subluxed hip were necessary.
When evaluated at 12 months of age, she was able to kick both legs while in the prone position through a full range of motion and was able to begin combat crawling using both legs reciprocally. She was able to move from sitting to prone and back to sitting using a rotational pattern. Ankle-foot orthoses were prescribed by the orthopedist at this time to correct bilateral pronation of her feet and for dorsiflexion weakness on the left. Additionally, the left ankle-foot orthosis was maintained in five degrees of dorsiflexion to position the left knee in slight flexion because the child hyperextended the left knee during supported standing. However, the orthoses restricted her active movement and were not tolerated well. Shortly after this reassessment, a revision of her ventriculoperitoneal shunt was performed. No loss of skills due to the surgery and hospitalization was observed.
Between 17 and 19 months, the child began assuming a quadruped position on her own and moved smoothly between quadruped and sitting. By 19 months, she was creeping using a cross-diagonal pattern and taking two to three independent steps using the walker. Additionally, by 19 months, she was pulling to stand at furniture and climbing onto furniture at home.
The orthosis for the right lower extremity was discontinued when the child was 24 months of age, but an articulating ankle-foot orthosis for the left lower extremity continued to be used. She maintained the left leg in extension, internal rotation, and adduction during ambulation with only 30 degrees of active flexion noted at the hip and knee during stepping. Without the orthosis, more flexion at the hip and knee and less internal rotation were noted. On the basis of these patterns of movement noted during ambulation, the articulating ankle-foot orthosis for the left lower extremity was discontinued when she was 36 month of age, and a foot orthosis was used for her pronated left foot.
She progressed from use of a posterior control walker to two quad canes at 29 months (Fig. 1), to one quad cane at three years, and finally to one standard cane at four years of age (Fig. 2). At 40 months, she was able to take five independent steps. By four years of age, she was taking up to 20 independent steps and was able to stop and stand independently (Fig. 3). As noted previously, she was assessed for her gross motor developmental skills at each visit using the PDMS. Table 1 illustrates her gross motor skill development and her chronological age from the time she entered the early intervention program until she entered a preschool program at 40 months of age. This table also demonstrates this child's delay in acquisition of gross motor skills as compared with a child who is developing typically. 9
Her scoliosis continued to increase in severity (from a Cobb angle of 10 degrees at birth to 48 degrees), and stabilization of her spine was recommended when she was approximately 18 months of age. However, the parents were concerned that the child would lose functional abilities as a result of the surgery. By 36 months of age, her scoliosis had progressed to 60 degrees (Fig. 4); the parents were again encouraged to consider surgical stabilization of the child's back, but they waited until she was six years old for this surgery.
Repeated measurements of the child's cognitive, language, socialization, and fine motor skills during the time that she was enrolled in the early intervention program revealed no delays in her acquisition of skills in these areas. She currently is a “straight A” student in the second grade and is considered academically gifted.
This child's progress in functional abilities has been dramatically different than what was anticipated from her diagnosis at birth. Typically, children with a meningomyelocele at the T7 through T9 vertebrae would demonstrate paralysis in the lower extremities and would have a loss of trunk strength as well. 10 Although the basic motor skills of rolling, combat crawling, and moving to a sitting position would be expected in a child even with a thoracic-level lesion, independent ambulation without use of assistive devices would not be. Standing and ambulation typically are goals for children with thoracic-level lesions, but primarily for exercise and for movement within the home or classroom. Additionally, the type of orthosis or walker that would typically be used with a child with a meningomyelocele at T7 through T9 vertebrae was not appropriate for this child. A total-contact orthosis with a thoracolumbar section to stabilize the pelvis and lumbar spine usually is recommended to provide proper alignment of the lower extremities. 11 A parapodium would have been used initially and later either a reciprocating gait orthosis or a hip-knee-ankle-foot orthosis. A “rollator” walker and perhaps either axillary or forearm crutches might have been anticipated as well. Children with thoracic-level scoliosis typically need wheelchairs for long distances and for outdoor travel. 11 The child described in this report, however, is ambulatory without use of any orthotics, walker, or crutches.
She was slightly delayed in reaching her major gross motor milestones, but by 48 months of age, she was able to stand alone and take up to 20 steps independently. However, because of the subluxed left hip and the scoliosis, she used a single cane during ambulation. She is able to walk for extended distances and is a functional ambulator on all types of surfaces. Given her original diagnosis and the lack of literature on the gross motor functioning of children with hemimeningomyelocele, we would have been unable to predict this long-term outcome for the child when she was an infant.
As expected from the review of the literature, this child continued to have an ever-increasing scoliotic curve. At five years of age, her x-rays revealed a progression of the curve to 72 degrees. Surgery was performed for stabilization of her scoliosis when she was six years of age. The parents’ decision to wait until the child was six years of age for the scoliosis surgery did not seem to cause any additional medical problems. In fact, the child's cooperation with her physical rehabilitation after surgery was enhanced by her age and cognitive level.
At present, the child is independent in her activities of daily living and has been toilet trained since 30 months with good bowel and bladder control. She has had no further revisions of her ventriculoperitoneal shunt. She is enrolled in a second grade class and participates fully in the classroom and in activities around the school. She receives direct services from physical therapy only four times yearly for reassessment of her functional skills and indirect services through the therapist's consultation with the classroom teacher regarding movement during the day. She also continues therapy through an interdisciplinary clinic at a local university with input from neurology, orthopedics, physical therapy, and prosthetics.
Hemimeningomyelocele at T7 through T9 vertebrae in this child resulted in a normally functioning right lower extremity and an involved left lower extremity. This is not typical of a child with meningomyelocele. Also not typical is the scoliosis that was present at birth and the progression of the curve that followed. Observation of scoliosis at birth along with meningomyelocele would strongly suggest the presence of a SCM with only one of the hemicords involved in the meningomyelocele. It is reasonable to assume that the scoliosis was related in part to the asymmetrical innervation. This child's progress was slow compared with children who are developing typically. However, she has progressed to a higher level of functioning than would have been expected for a child with a meningomyelocele at T7 through T9 vertebrae, and the outcome far exceeded the expectations of her healthcare providers and her parents.
© 2002 Lippincott Williams & Wilkins, Inc.