Central nervous system anomalies associated with meningomyelocele, hydrocephalus, and the Arnold-Chiari malformation: reappraisal of theories regarding the pathogenesis of posterior neural tube closure defects

Complete gross and microscopic neuropathological examinations of 25 children who died with meningomyelocele, the Arnold-Chiari malformation, and hydrocephalus revealed a wide range and frequency of associated central nervous system malformations. The most remarkable of these anomalies were hypoplasia or aplasia of cranial nerve nuclei (20%), demonstrable obstruction of cerebrospinal fluid flow within the ventricular system (92%), cerebellar dysplasia (72%), a disorder of migration of cortical neurons (92%), fusion of the thalami (16%), agenesis of the corpus callosum (12%), and complete or partial agenesis of the olfactory tract and bulb (8%). The anomalies associated with posterior neural tube closure defects can no longer be considered secondary, but rather must be considered part of a spectrum of malformations caused by an unidentified primary insult to the central nervous system. The frequency and pattern of brain malformations associated with neural tube defects of some children with meningomyelocele suggest that such malformations may seriously affect intellectual outcome.

The Chiari II malformation: cause and impact

INTRODUCTION

It is the Chiari II malformation and its effects that determine the quality of life of the individual born with spina bifida.

DISCUSSION

The cause of this malformation has been a source of debate for many years. Understanding the cause enables strategies for the management of problems created by this malformation to be developed. An open neural tube defect allows fluid to escape from the cranial vesicles, altering the intracranial environment and leads to all of the brain changes seen in the Chiari II malformation. Decompression of the intracranial vesicles causes overcrowding, decrease in the size of the third ventricle, and changes in the fetal skull. It also permanently links the intracranial ventricular system to the spinal cord central canal.

The spinal cord lesion in human fetuses with myelomeningocele: implications for fetal surgery

Recently produced experimental evidence suggests that secondary traumatic injury and degenerative changes, acquired in utero, to the openly exposed neural tissue may be primarily responsible for the massive neurological deficit associated with myelomeningocele (MMC). The goal of this study was to examine the morphology of human fetuses with MMC to determine if acquired trauma to the spinal cord could be identified. The MMC lesions with surrounding tissues from 10 human fetuses ranging in gestational age between 19 and 23 weeks were prepared with serial histological sections. The MMC lesions were characterized by an open vertebral arch, an open dura mater fused laterally to the dermis, and an open pia mater fused laterally to the epidermis. The spinal cord was exposed, without any meningeal, bony, or cutaneous covering, and was resting on the dorsal aspect of the abnormal arachnoid sac created by the fusion of the meninges to the cutaneous tissues. The exposed neural tissue had undergone varying degrees of recent traumatic injury as a result of its exposed position, ranging from nearly complete preservation of neural elements in four cases to nearly complete loss in two cases. The neural tissue remaining in the MMC with partial loss contained hemorrhages and abrasions from recent injury, suggesting that injury occurred during passage through the birth canal. The presence of dorsal and ventral parts of the cord with nerve roots and ganglia demonstrated that these structures had formed during development and that the loss of tissue by injury was a secondary change. The results support the concept that performing in utero surgery could protect the exposed but initially well-developed and uninjured cord, prevent secondary neural injury, and preserve neural function in the human fetus with myelomeningocele.

Creation of myelomeningocele in utero: a model of functional damage from spinal cord exposure in fetal sheep

A recent study in human fetuses with myelomeningocele (MMC) suggested that the primary malformation is not neural but a failed closure of the posterior vertebral column and paraspinal soft tissue, which leads to exposure and secondary destruction of the spinal cord. The goal of this study was to test whether chronic exposure of the normal spinal cord to the amniotic space produces a lesion similar to human MMC. In fetal sheep at 75 days' gestation (group A) and 60 days' gestation (group B) (term = 150 days), the lumbar spinal cord was exposed to the amniotic cavity by excising skin and paraspinal soft tissues, and by performing a laminectomy. Some animals from both groups were fetectomized and assessed morphologically at 100 days' gestation. The remainder were delivered near term and assessed clinically, electrophysiologically, and morphologically. In group A, all animals showed MMC-type pathology. The exposed spinal cord was herniated out of the spinal canal and rested on the dorsal membranes of a cystic sac. The neural tissue was stretched and flattened out. Histologically, the hallmarks of the spinal cord were not discernable and the cytoarchitecture was lost. These changes were less severe at 100 days than at term. The three survivors in group A were paraplegic. In group B, the two survivors and two fetuses harvested at 100 days had healed skin wounds and near normal spinal cord histology. The other animal harvested at 100 days had a MMC-type lesion with less severe histological changes. The two survivors had a mild paraparesis.(ABSTRACT TRUNCATED AT 250 WORDS)

In utero repair of experimental myelomeningocele saves neurological function at birth

In a previous series of fetal sheep experiments, the authors demonstrated that midgestational exposure of the normal spinal cord to the amniotic space leads to a myelomeningocele (MMC) at birth that closely resembles human MMC phenotypes in terms of morphology and functional deficit. The present study tested whether delayed in utero repair of such evolving experimental MMC lesions spares neurological function. In 12 sheep fetuses, a spina bifida-type lesion with exposure of the lumbar spinal cord was created at 75 days' gestation (full term, 150 days). Four weeks later, the developing MMC lesions were repaired in utero for seven fetuses (five fetuses died before this time). Of those that had repair, three were delivered near term by cesarean section, and four died in utero or were aborted. All survivors had healed skin wounds and near-normal neurological function. Despite mild paraparesis, they were able to stand, walk, and perform demanding motor tests. Sensory function of the hindlimbs was present clinically and confirmed electrophysiologically. No signs of incontinence were detected. Histologically, the exposed and then covered spinal cord showed significant deformation, but the anatomic hallmarks as well as the cytoarchitecture of the spinal cord essentially were preserved. These findings show that timely in utero repair of developing experimental MMC stops the otherwise ongoing process of spinal cord destruction and "rescues" neurological function by the time of birth. Because there is evidence that a similar secondary damage to the exposed neural tissue also occurs in human MMC, we propose that in utero repair of selected human fetuses might reduce the neurological disaster commonly encountered after birth.

Bladder wall abnormalities in myelodysplastic bladders: a computer assisted morphometric analysis

Myelodysplasia represents the most common cause of neurogenic bladder dysfunction in children. The specific histological features associated with myelodysplastic bladders have not been previously characterized. Our objective was to study the relationship between smooth muscle and connective tissue in control and myelodysplastic bladders using classical morphometric analysis with the assistance of an automated image analysis system. Gross histological analysis of the bladder specimens of normal stillborn fetuses showed organized muscle bundles embedded in a small amount of connective tissue. The bladder specimens of myelomeningocele stillborn fetuses showed a marked paucity of muscle bundles as well as a significantly diminished size of the muscle bundles. The myelomeningocele bladder specimens obtained from patients undergoing autopsy and those undergoing augmentation cystoplasty revealed significant interfascicular and pericellular infiltration of the smooth muscle by dense connective tissue. Quantitative morphometric analysis showed that the myelomeningocele stillborn fetuses have a significant increase in the volumetric content of connective tissue compared to control stillborn fetuses. The bladders of myelomeningocele patients who underwent autopsy or augmentation cystoplasty had a 3-fold increase in connective tissue when compared to normal controls. These findings reveal that structural changes in the histological components of the myelodysplastic bladder can be demonstrated not only in patients of varying ages undergoing autopsy or augmentation cystoplasty but also in the developing fetus. These findings enhance our understanding of the relationship of connective tissue proliferation to smooth muscle in the myelodysplastic bladder. We discuss the relationship of these findings to pathological detrusor morphology and detrusor dysfunction.

Retinoic acid induced myelomeningocele in fetal rats: characterization by histopathological analysis and magnetic resonance imaging

The prevention of human neural tube defects by folic acid administration and the potential for fetal surgical intervention for myelomeningocele (MMC) have renewed interest in the molecular pathways and pathophysiology of spina bifida. Animal models for assessment of the early developmental biology and pathophysiology of this lesion are needed. The goal of this study was to develop and characterize a non-surgical rat model of MMC. Time-dated Sprague-Dawley rats were gavage fed different doses of retinoic acid (RA) dissolved in olive oil at E10 (maternal n = 55, fetal n = 505). Control animals received olive oil alone (maternal n = 20, fetal n = 265) or were untreated (maternal n = 5, fetal n = 63). Fetuses were analyzed by detailed histopathology and MRI. Overall, isolated MMC occurred in 60.7% (307/505) of RA-exposed fetuses and no controls. Histopathology confirmed the entire spectrum of severity observed in human MMC, ranging from exposure of the cord with intact neural elements to complete cord destruction. MRI of the brain of MMC fetuses confirmed structural changes similar to humans with Arnold-Chiari malformation, including downward displacement of the cerebellum to just above the foramen magnum and compression of the developing medulla into a small posterior fossa. In conclusion, the RA-induced rat model of MMC is developmentally and anatomically analogous to human MMC. This relatively efficient and cost-effective model of MMC should facilitate investigation of the developmental biology and pathophysiology of MMC, and may be useful for the evaluation of further strategies for prenatal treatment.

Reduced hindbrain herniation after intrauterine myelomeningocele repair: A report of four cases

BACKGROUND

It has been theorized that fetal myelomeningocele repair may reduce ongoing intrauterine injury and perhaps allow healing and regeneration of dysplastic neural tissue. We report on the postnatal imaging studies of the first 4 patients to have undergone intrauterine myelomeningocele repair at our institution.

METHODS

Each of the 4 patients underwent postnatal sonographic and MRI. In addition, the postnatal ultrasounds of these 4 were compared to a group of retrospective controls.

RESULTS

MRI scans of the 4 experimental subjects revealed no evidence of hindbrain herniation while other stigmata of the Chiari-II malformation persisted. In comparison to the retrospective controls this absence of herniation was distinctly unusual.

CONCLUSION

Intrauterine myelomeningocele repair may reduce the degree of hindbrain herniation normally seen in patients with myelomeningocele. This raises the possibility that intrauterine repair may decrease the morbidity associated with the Chiari type-II malformation including brainstem dysfunction, hydrocephalus and syringomyelia.

Anomalous development of brain structure and function in spina bifida myelomeningocele

Spina bifida myelomeningocele (SBM) is a specific type of neural tube defect whereby the open neural tube at the level of the spinal cord alters brain development during early stages of gestation. Some structural anomalies are virtually unique to individuals with SBM, including a complex pattern of cerebellar dysplasia known as the Chiari II malformation. Other structural anomalies are not necessarily unique to SBM, including altered development of the corpus callosum and posterior fossa. Within SBM, tremendous heterogeneity is reflected in the degree to which brain structures are atypical in qualitative appearance and quantitative measures of morphometry. Hallmark structural features of SBM include overall reductions in posterior fossa and cerebellum size and volume. Studies of the corpus callosum have shown complex patterns of agenesis or hypoplasia along its rostral-caudal axis, with rostrum and splenium regions particularly susceptible to agenesis. Studies of cortical regions have demonstrated complex patterns of thickening, thinning, and gyrification. Diffusion tensor imaging studies have reported compromised integrity of some specific white matter pathways. Given equally complex ocular motor, motor, and cognitive phenotypes consisting of relative strengths and weaknesses that seem to align with altered structural development, studies of SBM provide new insights to our current understanding of brain structure-function associations.

Placental mesenchymal stromal cells rescue ambulation in ovine myelomeningocele

Myelomeningocele (MMC)-commonly known as spina bifida-is a congenital birth defect that causes lifelong paralysis, incontinence, musculoskeletal deformities, and severe cognitive disabilities. The recent landmark Management of Myelomeningocele Study (MOMS) demonstrated for the first time in humans that in utero surgical repair of the MMC defect improves lower limb motor function, suggesting a capacity for improved neurologic outcomes in this disorder. However, functional recovery was incomplete, and 58% of the treated children were unable to walk independently at 30 months of age. In the present study, we demonstrate that using early gestation human placenta-derived mesenchymal stromal cells (PMSCs) to augment in utero repair of MMC results in significant and consistent improvement in neurologic function at birth in the rigorous fetal ovine model of MMC. In vitro, human PMSCs express characteristic MSC markers and trilineage differentiation potential. Protein array assays and enzyme-linked immunosorbent assay show that PMSCs secrete a variety of immunomodulatory and angiogenic cytokines. Compared with adult bone marrow MSCs, PMSCs secrete significantly higher levels of brain-derived neurotrophic factor and hepatocyte growth factor, both of which have known neuroprotective capabilities. In vivo, functional and histopathologic analysis demonstrated that human PMSCs mediate a significant, clinically relevant improvement in motor function in MMC lambs and increase the preservation of large neurons within the spinal cord. These preclinical results in the well-established fetal ovine model of MMC provide promising early support for translating in utero stem cell therapy for MMC into clinical application for patients.

SIGNIFICANCE

This study presents placenta-derived mesenchymal stromal cell (PMSC) treatment as a potential therapy for myelomeningocele (MMC). Application of PMSCs can augment current in utero surgical repair in the well-established and rigorously applied fetal lamb model of MMC. Treatment with human PMSCs significantly and dramatically improved neurologic function and preserved spinal cord neuron density in experimental animals. Sixty-seven percent of the PMSC-treated lambs were able to ambulate independently, with two exhibiting no motor deficits whatsoever. In contrast, none of the lambs treated with the vehicle alone were capable of ambulation. The locomotor rescue demonstrated in PMSC-treated lambs indicates great promise for future clinical trials to improve paralysis in children afflicted with MMC.

Congenital tethered spinal cord syndrome in adults

OBJECT

The management of tethered spinal cord syndrome with onset of symptomatology occurring in adulthood remains controversial, although the necessity of early surgery in the pediatric tethered cord syndrome population is well established. To ascertain the results of surgery in adult patients with this anomaly, the authors undertook a retrospective review of 34 cases.

METHODS

The authors studied the hospital records of 34 consecutive patients who presented in adulthood with tethered cord syndrome and conducted follow-up phone interviews with 28 of them. The population consisted of 12 men and 22 women, ranging in age from 18 to 70 years (mean 34 years). The most common presenting feature was pain, followed by weakness and incontinence. All patients underwent surgery. The most common operative findings were tight filum terminale, split cord malformation, and lipomyelomeningocele, paralleling those observed in pediatric studies. Long-term surgical results and patient outcome ratings were encouraging. After a mean clinical follow-up period of 4 years, significant improvement occurred in 22 of 27 patients presenting with pain, 13 of 27 patients with motor or sensory dysfunction, and 11 of 18 patients with bowel and bladder disturbance. In addition, telephone interviews were obtained after a period of 8.6 years. Twenty-two (79%) of 28 patients called the operation a long-term success; 21 (75%) of 28 patients believed that they had significant postoperative improvement (and not just stabilization) in pain and/or neurological function. Surgical complications were generally minor. Nineteen (86%) of 22 employed patients returned to work after surgery. Two (33%) of six patients who were not employed before surgery worked full time postoperatively. Only two of the 28 patients interviewed had received Workers' Compensation benefits; both of these had good outcomes and returned to work.

CONCLUSIONS

Tethered spinal cord syndrome in adults is an uncommon entity that can become symptomatic. Although surgery in adults involves greater risk of neurological injury than in children, it is a low-risk procedure with encouraging results. Because neurological deficits are generally irreversible, early surgery is recommended.

MR imaging in the tethered spinal cord syndrome

MR examinations of the spine were reviewed in 25 patients with a clinical diagnosis of tethered spinal cord. In 21 patients (84%), the level of the tip of the conus was below the mid L2 vertebral body. The causes of the tethering were spinal lipomas (72%), tight filum terminale syndrome (12%), diastematomyelia (8%), and myelomeningocele (8%). These entities were readily identified in all instances. Bony dysraphisms were well demonstrated by MR. Interestingly, cavitary lesions/myelomalacia of the conus or the cord adjacent to the tethering lesion were seen with appropriate images in nine of 20 patients. This unexpected finding may have diagnostic and/or prognostic significance. Spinal MR was found to be extremely useful in the evaluation of the suspected tethered spinal cord. It was able to visualize the conus medullaris, assess the thickness of the filum terminale, identify traction lesions, and evaluate associated bony dysraphisms.

Surgical experience of 120 patients with lumbosacral lipomas

The surgical experience of 120 patients with lumbosacral lipomas is described. 47 of 120 patients were preoperatively found to be neurologically intact, the remaining 73 patients presented with various neurological signs including reflex changes, sensory disturbances, muscle weakness and sphincter problems. Neuro-imagings allowed a classification of lumbosacral lipomas into five types: (1) dorsal type; (2) caudal type; (3) combined type; (4) filar type; and (5) lipomyelomeningocele. Although all 120 patients underwent untethering of the spinal cord, the nerve roots passing through the lipoma itself and the neural tissues protruding externally to the spinal canal, respectively, tended to prevent satisfactory surgical removal of the lipoma in combined type lipomas and lipomyelomeningoceles. During 8.96 years of a mean postoperative follow-up period, there was no significant deterioration in most of the patients and some patients even improved in function. However, two patients with combined type lipomas developed neurological deterioration just after surgery, and five (two dorsal, two caudal and one combined type lipomas) did in the fashion of a late-onset. There are two different patient groups of lumbosacral lipomas; one group (caudal and filar type lipomas, and most of dorsal type lipomas) in whom the surgical anatomy is simple and satisfactory untethering surgery could be done without risk, and another (combined type lipomas and lipomyelomeningocele) in whom surgery would be accompanied with some risk and sometimes complete untethering could not be achieved because of the complicated anatomy of the lesion. Surgical difficulty of the latter group can be correlated with the increased frequency of neurological deterioration occurring just after the operation, but not of delayed one. Concerning prophylactic surgery for asymptomatic patients, the former group of patients are obviously good candidates, but the latter group is not.

Neurobiology of perceptual and motor timing in children with spina bifida in relation to cerebellar volume

The cerebellum is important for perceptual and motor timing in the mature brain, but the timing function of the cerebellum in the immature brain is less well understood. We investigated timing in children with spina bifida meningomyelocele (SB), a neural tube defect that involves cerebellar dysgenesis, and in age-matched controls. Specifically, we studied perceptual timing (judgements of 400 ms duration) and motor timing (isochronous motor tapping); measured cerebellar volumes; and related perceptual and motor timing to each other and to cerebellar volume measurements. Children with SB had impairments in the perception of duration (around 400 ms) but not frequency (around 3000 Hz), showing that their perceptual timing deficit was not a generalized auditory impairment. Children with SB had motor timing deficits on unpaced but not paced isochronous tapping, and their unpaced timing performance was associated with clock variance rather than with motor implementation. Perceptual and motor timing were correlated, suggesting that children with SB have impairments in a central timing mechanism. Children with SB, especially those with upper spinal cord lesions, had significant cerebellar volume reductions in grey and white matter, as well as different regional patterns of grey matter, white matter and CSF. Duration perception was correlated with cerebellar volumes, and the number of valid tapping trials was correlated with cerebellar volumes in the SB group, which data demonstrate structure-function relations between timing and cerebellar volumes.

Cervical myelomeningoceles

Cervical myelomeningoceles are rare dysraphic lesions. Nine cases of cervical myelomeningoceles are reported. The external features of all nine myelomeningoceles were strikingly similar: They were sturdy, tubular protuberances from the back of the infants' necks, covered at the base by full-thickness skin and covered on the dome by thick squamous epithelium. Internally, these were tethered cord lesions in which fibroneural bands or sagittal midline fibrous septa were tightly tethering the cervical spinal cord to the adjacent dural or intrasaccular soft tissues. Six of our early cases (Group 1) were initially treated with simple subcutaneous resection of the sac and ligation of the dural fistula without release of the internal tethering structures. Five of these children subsequently deteriorated 13 months to 8 years later, all with worsening hand function and spastic legs. All five were reexplored, and the tethering bands and septa were excised; all showed improvement. The other three neonates (Group 2) treated in the last 4 years underwent initial intradural exploration of the lesions; in one case, the tethering fibrous elements were only partially eliminated and the patient deteriorated 4 years later, but improved after a second operation for resection of a missed ventral fibrous septum. The other two Group 2 infants had a thorough release of the fibroneural stalks initially, and both were neurologically stable 3 years later. We recommend that cervical myelomeningoceles should be studied preoperatively with magnetic resonance imaging and computed tomographic myelography to identify the internal structures. The minimum initial surgical treatment should be a two-level laminectomy, intradural exploration, and excision of all tethering bands and septa, in addition to resection of the sac. If a split cord is revealed by imaging studies, both the ventral and dorsal surfaces of the hemicords must be carefully inspected to locate the median septum.

Apnea in patients with myelomeningocele

Apnea is a known complication of the Chiari II malformation presenting in infancy. Obstructive apnea secondary to bilateral abductor palsy or laryngomalacia and centrally mediated expiratory apnea with cyanosis can occur. Observations of 9 patients suggest that these forms of apnea may represent stages in a continuum of brain stem dysfunction due to the combined effects of the hindbrain malformation and its compression, hydrocephalus and progressive arachnoiditis. Obstructive apnea in some patients may be reversed by optimal control of hydrocephalus with or without cervical decompression. These patients may also develop episodes of cyanotic expiratory apnea of central origin (PEAC). This form of apnea does not respond to surgical or medical treatment and may show progressive worsening over time. Five of 6 patients with this form of apneic spell died suddenly, 2 of these died despite full recuscitative efforts. It is recommended that reports of treatment address results for both forms of apnea.

Severe neural tube defect syndrome from the Early Archaic of Florida

The Early Archaic Windover site is on the east coast of mid-peninsular Florida. A subadult skeleton (about 15 years old at time of death) was recovered with multiple pathologies related to spina bifida aperta of the neural arch at the L3-S2 level of the spine. Other evidence indicates s.b. cystica, although the degree of severity of the dysraphic neural tube syndrome cannot be directly determined. In addition to spina bifida, the lumbar region is scoliotic from malformation of zygapophyses. The defect is accompanied by severe infection of the right tibia and fibula, and disuse atrophy of long bones. It is hypothesized the NTD (neural tube defect) led to progressive sensory deprivation, which in turn led to increased loss of mobility, ulceration, and risk of serious infections. Other "minor" anomalies such as cone-shaped epiphyses, enlarged nutrient foramina, and vental vertebral cavitation are also discussed. The chronic nature of these defects provide insight on the high level of long-term care and attention provided a severely handicapped individual 7,500 years ago.

Histological features of congenital lipomas of the lower spinal canal

A study of 20 children with lipomyelomeningocele and two with intradural lipoma who underwent surgery revealed that five children had unusual and previously unreported histological findings. In each, the characteristic densely fibrous lipoma was present. One patient with an intradural lipoma had an ependymal-lined canal resembling a terminal ventricle. The subependymal layer was neuroglial and striated muscle fibers were scattered throughout adjacent connective tissue and lipoma. Three other children presented with lipomyelomeningoceles. In each case, the lipoma tapered to a firm fibrous tract which blended into conus medullaris. Microscopic examination of this fibrous tract showed it to contain not only a relatively acellular connective tissue stroma, but, in one case, sheets or islands of neuroglia and scattered nerve cells, in another, an epithelial cyst with a smooth muscle and fibrous tissue wall, and in a third case, a fragment of embryonic bone. These findings support the theory that there is a secondary phase to caudal neural tube development, and that congenital lipomas are formed by persistence and differentiation of ordinarily vestigial pluripotential embryonic cells. The fifth case, with extradural lipoma, diastematomyelia, and congenital dermal sinus, had a cyst at the junction of these structures. The cyst was lined by ciliated respiratory-like epithelium, and had mucous and serous glands in its wall. This finding supports the concept that formation of diastematomyelia depends on the prior existence of an accessory neurenteric canal.

Myelocystocele-cloacal exstrophy in a pedigree with a mitochondrial 12S rRNA mutation, aminoglycoside-induced deafness, pigmentary disturbances, and spinal anomalies

A large Filipino-American family with progressive matrilineal hearing loss, premature graying, depigmented patches, and digital anomalies was ascertained through a survey of a spina bifida clinic for neural crest disorders. Deafness followed a matrilineal pattern of inheritance and was associated with the A1555G mutation in the 12S rRNA gene (MTRNR1) in affected individuals as well as unaffected maternal relatives. Several other malformations were found in carriers of the mutation. The proband had a myelocystocele, Arnold-Chiari type I malformation, cloacal exstrophy, and severe early-onset hearing loss. Several family members had premature graying, white forelock, congenital leukoderma with or without telecanthus, somewhat suggestive of a Waardenburg syndrome variant. In addition to the patient with myelocystocele, two individuals had scoliosis and one had segmentation defects of spinal vertebrae. The syndromic characteristics reported here are novel for the mitochondrial A1555G substitution, and may result from dysfunction of mitochondrial genes during early development. However, the mitochondrial A1555G mutation is only rarely associated with neural tube defects as it was not found in a screen of 218 additional individuals with spina bifida, four of whom had congenital hearing loss.

The Rationale for in utero repair of myelomeningocele

OBJECTIVES

Despite advances in prenatal diagnosis, management of fetal myelomeningocele has been limited to abortion or supportive postnatal care. The rationale for fetal repair of myelomeningocele and initial clinical outcomes are discussed.

METHODS

A complete review of the literature concerning fetal myelomeningocele and repair was performed.

RESULTS

While myelomeningocele is a primary embryologic disorder, neurologic damage is also secondary to progressive in utero damage to the exposed spinal cord. Animal models with midgestational coverage of the spinal defect demonstrate near normal neurologic function at term. Early clinical results suggest that fetal closure can salvage neurologic function, reverse hindbrain herniation, and diminish the need for ventriculoperitoneal shunting.

CONCLUSIONS

In utero repair of myelomeningocele may improve neurologic outcomes and reduce hindbrain herniation in selected patients.

Clinical outcome differences for lipomyelomeningoceles, intraspinal lipomas, and lipomas of the filum terminale

Failure to differentiate between the different types of lumbosacral lipomas may lead to inaccurate assumptions and inappropriate management of patients. The goal of this study was to determine whether there is a difference in clinical outcome between patients with lipomyelomeningocles, intraspinal lipomas, and lipomas of the filum terminale. One hundred and fourteen patients with spinal dysraphism were seen at Duke University Medical Center between 1995-1999. All patients who had undergone previous operative intervention for these lesions were excluded. Twenty-two patients with intradural lipomas were identified. Of these, 14 (64%) had lipomyelomeningoceles and 8 (36%) had intraspinal lipomas. Twenty-five patients had filum terminale lipomas. Operative management consisted of lumbosacral laminectomies with microsurgical resection of the lipoma and division of the fatty filum. Average age at presentation in symptomatic patients with lipomas of the filum terminale was 17.7 years, and 23 years in the symptomatic intraspinal lipoma group. Patients with lipomyelomeningoceles ranged in age from 1 day to 18 years, with the majority being younger than 2 years. After an average follow-up of 8 months all patients showed improvement in motor strength following operative intervention. Greater improvements in sensory, bladder, and pain scores were associated with filum terminale lipomas. The least improvements in these categories were seen in the lipomyelomeningocele group. Motor strength is the most likely deficit to improve following operative intervention. Lipomyelomeningoceles, intraspinal lipomas, and filum termniale lipomas have different clinical outcomes following operative intervention.

Split cord malformations in myelomeningocele patients

Split cord malformations (SCMs) may occur in conjunction with myelomeningoceles, and are often ignored or misdiagnosed, potentially causing spinal cord tethering. In this paper, we study the incidence and clinical significance of such an association. We have retrospectively reviewed the medical records and radiographs of 20 myelomeningocele patients who had a SCM. These comprised at least 6% of our myelomeningocele patients. Five of the 20 had simultaneous repair of both lesions at birth. The other 15 were diagnosed with the SCM in a delayed fashion (mean age 4.4 years). Clinical presentations that prompted a diagnostic investigation included hypertrichosis (1), pain (2), routine radiographic follow-up (2), neurourological deterioration (10) and progressive scoliosis (5). In 17 of the 20 patients, the SCM involved the placode or was within one level of it. Fifteen of these were in the area of the placode or one segment above it. Five of the 20 patients had hypertrichosis and 15 of the 20 patients had a bony midline septum (i.e. type I SCM). Several accompanying spinal dysraphic lesions also contributed to the tethering: thickened (previously inconspicuous) filum terminale (6), syringohydromyelia (5) and a neurenteric cyst with a benign teratoma (1). Arachnoiditis secondary to the prior myelomeningocele repair was found, as expected, in all 15 patients. However, in virtually all patients, there was also evidence of tethering at the level of the SCM. Long-term follow-up showed stabilization of preoperative symptoms and signs, whereas complications of the operation and clinical evidence of retethering were uncommon. Myelomeningocele patients should be screened with clinical examinations looking for hypertrichosis and with spinal radiographs preoperatively looking for evidence of SCM (bony midline septum and/or interpedicular widening not due to the myelomeningocele). Intraoperatively, the placode and the rostral spinal cord segment should be carefully inspected for an SCM and other dysraphic lesions.

Hypertrophy of labia minora in myelodysplastic women. Labioplasty to ease clean intermittent catheterization

Female myelodysplastic patients are sometimes annoyed by hypertrophy of the labia minora, possibly caused by long-term diaper dermatitis. This condition makes intermittent catheterization difficult and impairs the cleanliness and aesthetic appearance of the external genitalia. We successfully performed labioplasty on 3 myelodysplastic females.

Limbic tract anomalies in pediatric myelomeningocele and Chiari II malformation: anatomic correlations with memory and learning--initial investigation

PURPOSE

To prospectively determine anomalies of limbic tracts and to describe the relationship between these anomalies, seen on diffusion-tensor magnetic resonance (MR) and fiber tract (FT) reconstruction images, and learning and memory in children with myelomeningocele (MM) and Chiari II malformation.

MATERIALS AND METHODS

The investigation was HIPAA compliant and approved by institutional review boards; informed consent was obtained. In seven male and six female patients (aged 6 months to 16 years) with MM and Chiari II malformation, diffusion-tensor imaging and FT reconstruction were performed. FT reconstruction was generated with fractional anisotropy continuous tracking algorithm and manually drawn regions of interest. Limbic tract abnormalities were assessed on FT reconstruction images by an experienced pediatric neuroradiologist blinded to results of cognitive testing. Nine patients met criteria for memory and learning testing by a trained cognitive neuroscientist blinded to MR results. Exact Wilcoxon rank sum test was used to compare performance with learning and memory tasks in two groups.

RESULTS

Eleven of 13 patients had defects within fornices and/or cingulum; three patients had aberrant fibers of cingulum. In nine patients, six had deficits in general memory; four, in learning; and four, in both. Atresia or hypoplasia of crura and body of fornices was noted in six patients with memory deficits and four patients with learning deficits. Five of six patients with memory deficits and three of four with learning deficits had hypoplasia or atresia of cingulum. Exact Wilcoxon rank sum test demonstrated significantly poorer performance for nonverbal immediate recall tasks in patients with anomalies of the fornix compared with those without (P = .04, exact two-tailed test).

CONCLUSION

Diffusion-tensor and FT reconstruction images revealed that limbic fiber abnormalities were common in patients with MM and Chiari II malformation. Nonverbal immediate recall task performance appeared to be related to abnormalities of the fornix.