Unjoined primary and secondary neural tubes: junctional neural tube defect, a new form of spinal dysraphism caused by disturbance of junctional neurulation

INTRODUCTION

Primary and secondary neurulation are the two known processes that form the central neuraxis of vertebrates. Human phenotypes of neural tube defects (NTDs) mostly fall into two corresponding categories consistent with the two types of developmental sequence: primary NTD features an open skin defect, an exposed, unclosed neural plate (hence an open neural tube defect, or ONTD), and an unformed or poorly formed secondary neural tube, and secondary NTD with no skin abnormality (hence a closed NTD) and a malformed conus caudal to a well-developed primary neural tube.

METHODS AND RESULTS

We encountered three cases of a previously unrecorded form of spinal dysraphism in which the primary and secondary neural tubes are individually formed but are physically separated far apart and functionally disconnected from each other. One patient was operated on, in whom both the lumbosacral spinal cord from primary neurulation and the conus from secondary neurulation are each anatomically complete and endowed with functioning segmental motor roots tested by intraoperative triggered electromyography and direct spinal cord stimulation. The remarkable feature is that the two neural tubes are unjoined except by a functionally inert, probably non-neural band.

CONCLUSION

The developmental error of this peculiar malformation probably occurs during the critical transition between the end of primary and the beginning of secondary neurulation, in a stage aptly called junctional neurulation. We describe the current knowledge concerning junctional neurulation and speculate on the embryogenesis of this new class of spinal dysraphism, which we call junctional neural tube defect.

MRI of closed spinal dysraphisms

We present a pictorial review of MRI features of various closed spinal dysraphisms based on previously described clinicoradiological classification of spinal dysraphisms proposed. The defining imaging features of each dysraphism type are highlighted and a diagnostic algorithm for closed spinal dysraphisms is suggested.

Congenital spinal lipomatous malformations: part II--Clinical presentation, operative findings, and outcome

BACKGROUND

To report this author's experience with patients with a congenital spinal lipomatous malformation with special emphasis on variations in clinical presentation, operative findings, and outcome based on the classification scheme proposed in the first part of this two part article.

METHODS

From January 1995 to July 2005, 80 patients with a congenital spinal lipomatous malformation were treated. All patients underwent routine neurological examination, plain radiographs of the spine and all but 10 patients underwent MRI. Ten patients underwent CT-myelography. Hoffman's functional grading scale was used for preoperative and postoperative clinical assessment. The operative findings, complications and outcome were assessed.

FINDINGS

Age ranged from 18 days to 19 years. The female: male ratio was 3:2. The malformations were divided into two groups: Group I: Lipomas without a dural defect and, Group II: Lipomas with a dural defect. Included in Group I were: 22 patients out of which there were Caudal lipomas: 10, Filum lipomas:11 and intramedullary lipoma: 1. In Group II there were 58 patients out of which there were Dorsal lipomas: 8, Caudal lipomas with dural defect: 8, Transitional lipomas: 10, lipomyelomeningoceles:28, lipomyeloceles: 4. Most of the group I patients were >5 years of age; cutaneous markers were absent in 60%, older children more often presented with sphincter disturbances. Surgery in group I was straight forward and consisted of sectioning of the filum in filum lipomas, debulking and untethering in caudal lipomas. Duroplasty was seldom required. CSF leak was rare. No patient deteriorated following surgery and no retethering was noted during follow-up. In Group II, all patients had cutaneous markers, most were <2 years of age, 19 were asymptomatic, older children had more severe neurological deficits. Duroplasty was required in most cases. A CSF leak occurred in 12%. Two patients deteriorated temporarily following surgery. Two patients presented with retethering 4 and 8 years after initial surgery. Improvement of more than one Hoffman's functional grade occurred when surgery was done <2 years of age.

CONCLUSIONS

Congenital spinal lipomatous malformations do not constitute a single homogenous entity. They can be broadly classified into two groups depending on the presence or absence of a dural defect. These two groups are different from one another embryologically, clinically, surgically and prognostically.

Spinal sonography in newborns and infants - part II: spinal dysraphism and tethered cord

Patients with cutaneous markers in the lumbo-sacral region as well as infants with bladder and bowel dysfunction, orthopedic anomalies and progressive neurological dysfunction are at risk for spinal dysraphism and tethered cord. Three types of spinal dysraphism can be distinguished: Type I - open spinal dysraphisms with a non-skin covered back mass; type II - closed spinal dysraphisms with a skin covered back mass; type III - occult spinal dysraphisms without a back mass. All spinal dysraphisms can be associated with a tethered cord, characterized by a low position of the conus medullaris below L3. Type I dysraphisms are meningomyeloceles and myeloceles, which are associated with CHIARI-II malformations characterized by the low position of the cerebellar vermis within the foramen magnum. Type II dysraphisms are lipomyeloceles, lipomyelomeningoceles, posterior meningoceles and myelocystoceles. Lipomeningoceles and lipomyelomeningoceles are characterized by a subcutaneous echogenic mass which communicates with the spinal canal and may cause tethered cord. Posterior meningoceles are, dorsal cystic space occupying lesions without internal neural tissue. Myelocystoceles are characterized by a cystic dorsal mass which communicates with a dilated central canal characteristic of syringo-hydromyelia. Type III dysraphisms without a back mass are frequently associated with cutaneous markers in the lumbo-sacral region. Sonographically dermal sinus tracts, diastematomyelia, tight filum and lipoma of the filum terminale and the caudal regression syndrome have to be distinguished. Dermal sinuses are characterized by an echogenic tract from the skin to the spinal canal, often associated with a spinal dermoid. Diastematomyelia is characterized by a complete or partial duplication of the spinal cord which can only be shown on axial images. Tight filum terminale or lipoma of the filum terminale is characterized by a thick echogenic filum with a diameter of more than 2 mm, and a conus below L3.

CONCLUSION

All different forms of spinal dysraphisms and tethered cord can be diagnosed sonographically in the neonatal period as long as the spinal arches are not completely ossified.

Quality of Life and Continence in Patients with Spina Bifida

PURPOSE

Spina bifida (SB) is the most common congenital cause of incontinence in childhood. This study attempts to determine the relationships between urinary/faecal incontinence, methods of management, and Health Related Quality of Life (HRQoL) in people with SB.

PATIENTS AND METHOD

A total of 460 patients (300 adults and 160 adolescents) from six centres in France have taken part in this cross-sectional study. Clinical outcome measures included walking ability, urinary/faecal continence, and medical management. HRQoL was assessed using the SF36 in adults and the VSP in adolescents and their parents. Univariate and multivariate analysis was used to determine the relationships between clinical parameters and HRQoL.

RESULTS

HRQoL were significantly lower than in the general population. Adult women had significantly lower scores than men, and adolescent females had significantly lower scores for psychological well being. We did not found strong relationship between incontinence and HRQoL in this population. Moreover patients surgically managed for urinary/fecal incontinence did not show significantly higher scores of HRQoL.

CONCLUSION

Using generic HRQoL measures, urinary/faecal incontinence and their medical management may not play a determinant role in HRQoL of persons with SB. However many other factors affect HRQoL in these patients. A longitudinal study design is recommended to assess whether incontinence management is associated with improved HRQoL.

Epilepsy in patients with spina bifida in the lumbosacral region

This study aimed to assess the relevance of epilepsy and spina bifida in the lumbosacral region. We evaluated 75 patients with spina bifida admitted to the Kyushu University Hospital from 1980 to 2004. Patients were classified as having meningocele (MC, 4 cases), myelomeningocele (MMC, 6), myeloschisis (MS, 45), and lumbosacral lipoma (LL, 20). Nine cases had epileptic disorders, and all showed MS. Meticulous neuroradiological investigations revealed cerebral abnormalities such as polymicrogyria or hypogenesis of the corpus callosum in all epileptic cases. Locations of cerebral abnormalities topographically correlated with areas of interictal EEG abnormalities. Although all epileptic cases had ventriculoperitoneal (VP) shunt for hydrocephalus before the onset of epilepsy, interictal EEG abnormalities could not be explained by location of the VP shunt. In all LL patients, neither history of epilepsy nor cerebral abnormalities were noted on magnetic resonance imaging (MRI). Epileptogenesis in spina bifida patients seemed to correlate with coexisting cerebral abnormalities in MS patients rather than with the VP shunt. However, not all spina bifida patients associated with cerebral abnormalities had epilepsy, and not all cerebral abnormalities were epileptogenic, suggesting that epilepsy in spina bifida patients was multifactorial.

Cutaneous lesions in occult spinal dysraphism--correlation with intraspinal findings

OBJECTS

This study was conducted to investigate the frequency and type of cutaneous stigmata in different forms of occult spinal dysraphism (OSD) and their correlation to the underlying malformation.

METHODS

Fourteen different forms of spinal malformations were identified in 358 operated patients with OSD. Most frequent findings (isolated or in combinations) were spinal lipoma, split cord malformation, pathologic filum terminale, dermal sinus, meningocele manqué, myelocystocele and caudal regression. Stigmata were present in 86.3% of patients, often in various combinations. Using a binary logistic regression analysis, significant correlations with distinct malformations were found for subcutaneous lipomas, skin tags, vascular nevi, pori, hairy patches, hypertrichosis, meningoceles and "cigarette burn" marks.

CONCLUSIONS

Cutaneous markers in a high percentage accompany spinal malformations. Due to the correlations of different stigmata to distinct malformations, they can aid the clinician in further diagnostic and therapeutic work.

Spinal dysraphism: MR imaging rationale

Spinal cord development occurs through the three consecutive periods of gastrulation (weeks 2-3), primary neurulation (weeks 3-4), and secondary neurulation (weeks 5-6). Spinal cord malformations derive from defects in these early embryonic stages, and are collectively called spinal dysraphisms. Spinal dysraphisms may be categorized clinically into open and closed, based on whether the abnormal nervous tissue is exposed to the environment or covered by skin. Open spinal dysraphisms include myelomeningocele and other rare abnormalities such as myelocele, hemimyelomeningocele, and hemimyelocele, and are always associated with a Chiari II malformation. Closed spinal dysraphisms are further divided into two subsets based on whether a subcutaneous mass is present in the low back. Closed spinal dysraphisms with mass comprise lipomyelocele, lipomyelomeningocele, meningocele, and myelocystocele. Closed spinal dysraphisms without mass comprise simple dysraphic states (tight filum terminale, filar and intradural lipomas, persistent terminal ventricle, and dermal sinuses) and complex dysraphic states. The latter category involves abnormal notochordal development, either in the form of failed midline integration (ranging from complete dorsal enteric fistula to neurenteric cysts and diastematomyelia) or of segmental agenesis (caudal agenesis and spinal segmental dysgenesis). Magnetic resonance imaging is the imaging modality of choice for evaluation of this complex group of disorders.

Spinal ultrasound in infants

This paper discusses the indications for spinal ultrasound, including its advantages and disadvantages compared with spinal MRI. The features and ultrasound findings both in normal infants and in those with spinal dysraphism are reviewed.

Magnetic resonance imaging of spinal dysraphism

Spinal cord development occurs through three consecutive periods. Gastrulation (weeks 2-3) is characterized by conversion of the embryonic disk from a bilaminar to a trilaminar arrangement and establishment of a notochord. Primary neurulation (weeks 3-4) produces the uppermost nine tenths of the spinal cord. Secondary neurulation and retrogressive differentiation (weeks 5-6) result in formation of the conus tip and filum terminale. Defects in these early embryonic stages produce spinal dysraphisms, which are characterized by anomalous differentiation and fusion of dorsal midline structures. Spinal dysraphisms may be categorized clinically into two subsets. In open spinal dysraphisms, the placode (non-neurulated neural tissue) is exposed to the environment. These disorders include myelomeningocele, myeloschisis, hemimyelomeningocele, and hemimyelocele, and are always associated with a Chiari II malformation. Closed spinal dysraphisms are covered by intact skin, although cutaneous stigmata usually indicate their presence. Two subsets may be identified based on whether a subcutaneous mass is present in the low back. Closed spinal dysraphisms with mass comprise lipomyeloschisis, lipomyelomeningocele, meningocele, and myelocystocele. Closed spinal dysraphisms without mass comprise complex dysraphic states (ranging from complete dorsal enteric fistula to neurenteric cysts, split cord malformations, dermal sinuses, caudal regression, and spinal segmental dysgenesis), bony spina bifida, tight filum terminale, filar and intradural lipomas, and persistent terminal ventricle. Magnetic resonance imaging is the imaging method of choice for investigation of this complex group of disorders.

MR spectrum in spinal dysraphism

Spinal dysraphism is a general term which encompasses a wide variety of anomalies of the spine, all of which result from imperfect midline fusion of the embryonic neural tube. This term refers to large defects that involve the spine and not to small vertical clefts commonly seen within the spinal process of L5 or S1. We present a spectrum of MR imaging findings selected from a retrospective review of 100 patients of spinal dysraphism evaluated at our institution.

Spina bifida and other neural tube defects

NTDs, resulting from failure of the neural tube to close during the fourth week of embryogenesis, are the most common severely disabling birth defects in the United States, with a frequency of approximately 1 of every 2000 births. Neural tube malformations involving the spinal cord and vertebral arches are referred to as spina bifida, with severe types of spina bifida involving protrusion of the spinal cord and/or meninges through a defect in the vertebral arch. Depending on the level of the lesion, interruption of the spinal cord at the site of the spina bifida defect causes paralysis of the legs, incontinence of urine and feces, anesthesia of the skin, and abnormalities of the hips, knees, and feet. Two additional abnormalities often seen in children with spina bifida include hydrocephalus and the Arnold-Chiari type II malformation. Despite the physical and particular learning disabilities children with spina bifida must cope with, participation in individualized educational programs can allow these children to develop skills necessary for autonomy in adulthood. Advances in research to uncover the molecular basis of NTDs is enhanced by knowledge of the link between both the environmental and genetic factors involved in the etiology of NTDs. The most recent development in NTD research for disease-causing genes is the discovery of a genetic link to the most well-known environmental cause of neural tube malformation, folate deficiency in pregnant women. Nearly a decade ago, periconceptional folic acid supplementation was proven to decrease both the recurrence and occurrence of NTDs. The study of folate and its association with NTDs is an ongoing endeavor that has led to numerous studies of different genes involved in the folate metabolism pathway, including the most commonly studied thermolabile mutation (C677T) in the MTHFR gene. An additional focus for NTD research involves mouse models that exhibit both naturally occurring NTDs, as well as those created by experimental design. We hope the search for genes involved in the risk and/or development of NTDs will lead to the development of strategies for prevention and treatment. The most recent achievement in treatment of NTDs involves the repair of meningomyelocele through advancements in fetal surgery. Convincing experimental evidence exists that in utero repair preserves neurologic function, as well as resolving the hydrocephalus and Arnold-Chiari malformation that often accompany meningomyelocele defects. However, follow-up is needed to completely evaluate long-term neurologic function and overall improved quality of life. And in the words of Olutoye and Adzick, "until the benefits of fetal [meningomyelocele] repair are carefully elucidated, weighed against maternal and fetal risks, and compared to conventional postnatal therapy, this procedure should be restricted to a few centers that are committed (clinically and experimentally) to investigating these issues."

Spinal dysraphism: a review of neuroradiological features with embryological correlations and proposal for a new classification

Our purpose was to review the neuroradiological features of spinal dysraphism and to correlate them with clinical findings and up-to-date embryological theory. We also aimed to formulate a working classification which might prove useful in clinical practice. We reviewed series of 986 children referred to our Spina Bifida Centre in the past 24 years. There were 353 children with open spinal (OSD) and 633 with closed (skin-covered) spinal (CSD) dysraphism. By far the most common open abnormality was myelomeningocele, and all patients with OSD had a Chiari II malformation. CSD was categorised clinically, depending on the presence of a subcutaneous mass in the back. CSD with a mass mainly consisted of lipomas with dural defects and meningoceles, and accounted for 18.8 % of CSD. CSD without a mass were simple (tight filum terminale, intradural lipoma) or complex (split cord malformations, caudal regression). Our suggested classification is easy to use and to remember and takes into account clinical and MRI features; we have found it useful and reliable when making a preoperative neuroradiological diagnosis in clinical practice.

Pediatric neurosurgical disease

The most common, primary referrals to a pediatric neurosurgeon's office are the evaluation and management of the child with a large head (to rule out hydrocephalus and other space occupying lesions) a mishappen head (to rule out various forms of craniosynostosis), or some form of congenital spinal abnormality (spinal dysraphism). The authors discuss the pathogenesis and clinical features of these disorders, provide a framework for diagnostic evaluation and referral, and discuss the various treatment options available for each.

Imaging in hydrocephalus and spinal dysraphism

Hydrocephalus and spinal dysraphism are two commonly encountered clinical entities where imaging plays a vital role. Sonography, Computed Tomography and Magnetic Resonance Imaging are the modalities used for the evaluation of hydrocephalus. Ultrasound is useful in small infants with open fontanella, is non-invasive and can be performed at cribside. However, it has limitation in identifying the etiology. CT is the most cost effective modality in the evaluation of hydrocephalus and gives detailed anatomical information. MRI offers the added advantage of multiplanar display and can also assess stenosis/patency of CSF pathways, using phase contrast cine techniques. MRI is the modality of choice for evaluating spinal dysraphism and gives excellent information regarding contents of back mass, spinal cord status and associated anomalies like Chiari malformation. Myelography coupled with CT should be reserved for equivocal cases or in centres where MRI is not available.

Rehabilitation of patients with spina bifida

Patients with spina bifida present with multifarious problems requiring multi-disciplinary approach for their rehabilitation. 172 patients of spina bifida attending the Department of Physical Medicine and Rehabilitation at A.I.I.M.S., New Delhi, were studied retrospectively to ascertain the problems posed by them while presenting for rehabilitation. Male:female ratio was 1.23:1. Lumbo-sacral lesion comprised 41.3% followed by lumbar (26.1%) and sacral (22.1%). Common spinal deformities observed were Kyphoscoliosis (62.2%) and increased lumbar lordosis (19.2%). Clinically, active signs and symptoms of hydrocephalus were found in 47.7% associated with mental subnormality in 22.1%. Varying degrees of weakness of the muscles of lower limbs were detected in 98.3% cases, spasticity was found in 10.5% and ataxia in 2.9%. Improvement of muscle power was noticed in 45.3% during first three years and deterioration in 10.5% due to various complications. Foot deformities were commonest amongst deformities. Mobility was affected in 55.8% while 62.2% could attain independence. Bladder symptoms were present in 75% cases and bowel symptoms in 26.7%. Anxiety and guilt amongst parents was high in the families. Main hindering factors in vocational rehabilitation were bladder control, ambulation and pressure sores.

Spina bifida

Spina bifida is the most common central nervous system birth defect encountered by the pediatric neurosurgeon. It is defined by characteristic development abnormalities of the vertebrae and spinal cord and associated changes in the cerebrum, brainstem and peripheral nerves. The expression of spina bifida encompasses the entire central nervous system, ranging in severity from merely an absent spinous process with normal intraspinal structures to the other extreme of myelomeningocoele, Chiari malformation, hydrocephalus, and cortical cytoarchitectural changes. Most children with myelomeningocoele have some degree of weakness of their lower extremities and many have significant orthopaedic problems. As a result of denervation, muscle imbalance ensues and can result in abnormalities at the hip, knee and foot. Anesthesia of various portions of the skin can lead to pressure sores, particularly later in life. Anorectal neuropathy may cause a variety of defecatory dysfunctions. Urologic abnormalities are also common. These multisystem abnormalities associated with spina bifida contribute to its widely accepted identity as the most complex development defect compatible with long life.

Spinal and cranial neural tube defects

Developmental lesions of the central nervous system with failure of normal midline fusion are often referred to as being dysraphic and vary from inapparent and insignificant to a massive deformity incompatible with survival. Several different schemata are used to classify this wide variety and often complex set of malformations; however, the nomenclature is confusing and even contradictory. As most of these congenital lesions of clinical significance involve an aberration in the formation of the neural tube, it is suggested that the term neural tube defects (NTD) be used to characterize this entire group of anomalies. From a practical clinical standpoint, NTD can be subdivided into three main groupings: open spinal NTD, closed spinal NTD, and cranial NTD. This article briefly covers the epidemiology, embryology, classification, clinical presentation, and management of this group of congenital lesions.

Heterogeneity of spina bifida

Splitting birth defects into dysmorphologically homogeneous groups might improve the ability to detect a genetic risk factor or teratogenic exposure. With regard to spina bifida, recent studies suggest that etiologic heterogeneity exists within the group of spina bifida, although exogenous risk factors have been sparsely evaluated for subgroups. In the present study, 210 spina bifida patients were classified into relatively homogeneous groups, based on retrospective information on appearance and functional aspects of the lesion abstracted from medical records of the patients. We compared high with low spina bifida, and open with closed spina bifida, and investigated whether risk factors for spina bifida such as maternal age, antiepileptic drug use, parental occupation, and genetic factors were specifically associated with these homogeneous subclasses. For these comparisons, a referent group of 671 children was used. Although classifying spina bifida into homogeneous subclasses presented some difficulties and numbers were small, this study provides some evidence for different risk profiles for subclasses of spina bifida. The sex ratio, the proportion of miscarriages of siblings, and maternal age did not differ among the different subclasses of spina bifida. However, children with a positive family history of neural tube defects (NTDs) had a higher risk of high spina bifida [odds ratio (OR) = 6.3, 95% confidence interval (CI): 1.7-19.2] than of low spina bifida (OR = 2.1, 95% CI: 1.0-4.2). Siblings with NTDs were more common in cases with high spina bifida and cases with open spina bifida. A strongly increased risk of high spina bifida was found for male welders (OR = 12.1, 95% CI: 1.5-64.2), whereas the risk of low spina bifida was much lower (OR = 1.6, 95% CI: 0.2-7.9). For mothers with agricultural occupations, a strongly increased risk was observed for open spina bifida (OR = 14.3, 95% CI: 2.9-77.7), whereas none of 107 cases with closed spina bifida had a mother with an occupation in agriculture. Due to small numbers, the results must be interpreted with caution.

Three-dimensional gait analysis in spina bifida

This study was designed to determine gait patterns in children with lumbar and sacral neurologic level spina bifida. We studied a group of 28 children: 10 had L4-level lesions and a mean age of 11 years; eight had L5-level lesions and a mean age of 8 years; and 10 had S1-level lesions with a mean age of 12 years. A group of 15 normal children, mean age 10 years, was used for comparison. Each child underwent three-dimensional gait analysis using the Vicon system. We found that there were recognisable gait patterns for each level of spina bifida and that the abnormalities accurately reflected the muscle deficiencies present. The gait patterns approximated more closely to those of the normal group as the neurological level descended. The most important findings were of increased pelvic obliquity and rotation with hip abduction in stance (reflecting the gross Trendelenburg-type gait seen in these children) and persistent knee flexion throughout stance as a result of the absence of the plantar flexion-knee extension couple. We found that gait was not improved by tendon transfers performed either at the hip (posterolateral psoas transfer) or at the ankle (tibialis anterior transfer).

Epidemiologic characteristics of phenotypically distinct neural tube defects among 0.7 million California births, 1983-1987

Isolated neural tube defects (NTDs) appear to have different risk factors compared to nonisolated NTDs. To extend those observations, we explored routinely collected child and parental characteristics as possible risk factors among isolated versus nonisolated NTD cases, among high versus low spina bifida cases, and among open versus skin-covered spina bifida case. Fetuses and liveborn infants with anencephaly or spina bifida among the 1983-87 cohort of births and fetal deaths (n = 712,863) were ascertained by the California Birth Defects Monitoring Program. One hundred and ninety-three anencephalic cases and 272 spina bifida cases were compared to a random sample of 5,000 liveborn infants. Among anencephalic cases, 55% were livebirths and 85% were isolated. The proportion of males was similar to females across all subgroups. Increased risks were found for Hispanic whites, with risk estimates highest for nonisolated cases (odds ratio = 4.0, 95% confidence interval [1.5, 10.5]). Among spina bifida cases, 92% were livebirths, 81% isolated, 82% open, and 86% were low. More males were found among the group with isolated high open defects, and fewer males were found among the group of all closed defects. The proportion of males was similar to females in all other subgroups. Cases were more likely to be Hispanic with risks largest for high open defects (odds ratio = 2.9, [1.2,6.6]), particularly for nonisolated cases. This study provides some evidence that further classifications of NTDs may reveal subgroupings of cases with different etiologies.

Spina bifida. Part 1. Physical effects

The author delineates types of spina bifida and focuses on meningomyelocele. Children with meningomyelocele have varying sensory and motor impairments. Clues to potential problems are offered.

A proposed grading and scoring system for spina bifida: Spina Bifida Neurological Scale (SBNS)

Neurological symptoms present in neonates with spinal dysraphism often progress with growth. A simple, objective scoring system for quantitative analysis of spinal neurological deficits, called the Spina Bifida Neurological Scale (SBNS), is proposed. Scoring is based on (1) motor function, (2) reflexes, and (3) bladder and bowel function. These are each divided into six, four, and five points respectively with respect to the level of spinal function. Motor function and reflexes are bilaterally analyzed, and the maximum SBNS score of 15 points reflects a normal spinal neurological state (grade I). This scoring system was correlated with the clinical condition of 89 patients with spina bifida who were graded from I to V. A total score of less than 5 was associated with a nonambulatory state (grade IV or V) in 84.0% of patients, and a score of 5-9 was associated with an ambulatory state (grade III) in 93.8% of patients. Scores of 10-14 reflected control of bladder and bowel function (grade II) in all patients. The application of a standardized scoring scheme will assist in the evaluation of patients' clinical status and will enable analysis of chronological changes in neurological function.

Do familial neural tube defects breed true?

The tendency for sibs affected by non-syndromal neural tube defect (NTD) to have the same type of lesion was assessed retrospectively in a series of 66 affected sibships from the west of Scotland. Different schemes were used to classify the lesions: in the simplest classification into either anencephaly (including anencephaly-spina bifida) or spina bifida there was a tendency for spina bifida to breed true. More detailed description of the NTD in 48 sibships permitted classification according to location on the neuraxis; in this scheme sibs had dissimilar lesions. In 48 sets of affected sibs the lesions were separable into high NTD, which had involvement above vertebral level T12, and low NTD, which did not extend above T12. Low lesions comprised a minority of the total and each one occurred in a sibship with a high lesion. These results do not support the idea that NTDs occurring above and below vertebral level T12 have a different genetic basis.

Follow-up of spina bifida children with and without upper renal tract changes at birth

The aim of this study was to assess 2 groups of children with spina bifida; one with and the other without upper renal tract (URT) changes at birth and to evaluate the outcome of their management. In Group 1, there were 148 patients who had normal URT at birth. They were studied for a mean follow-up of 131 months. Twenty-eight per cent developed URT changes in later life. The median time interval for URT changes to develop between birth and the first assessment which showed abnormal finding, was 33 months and between the last normal URT assessment and the development of URT changes, was 16 months. Six patients with URT changes were treated conservatively and 36 required intervention. Twenty-eight of 42 patients showed initial improvement of URT changes but 25 subsequently deteriorated. In 3 patients renal function deteriorated with renal failure in one and renal impairment in 2. In Group 2, 24 patients who had URT changes present at birth were also studied for a mean follow-up of 115 months. The URT changes in 8 patients deteriorated after the initial assessment over a median time of 15 months. Twelve patients' URT changes improved spontaneously without active intervention over a median time interval of 16 months but 5 subsequently deteriorated. Overall, the prognosis of children with URT changes at birth did not seem to be any worse than children developing changes later in life. Lesions of sacral and thoraco-lumbar regions of the spine were most commonly associated with URT changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Spinal dysraphisms

The practitioner is faced with the challenge of identifying occult presentations of spinal dysraphism and providing follow-up treatment of foot and leg deformities. The initial symptoms of a spinal dysraphic condition may be subtle and involve the lower extremity. An increased understanding of spinal dysraphism will encourage early diagnosis and prompt effective treatment.

The embryology of spinal dysraphism

The theories of abnormal embryogenesis suggested as explanations for the various forms of SBA and occult spinal dysraphism appear in some instances too all encompassing, as in Gardner's hydrodynamic theory or Padget's neuroschisis theory, or too limited, as in the theory of arrested development proposed by Daniel and Strich for the ACM, or just too speculative in many cases. The observation of a completed defect does not allow one to venture backwards in development to a specific time and cause with any accuracy. Perhaps several different causes striking different tissues at different times can set up a series of aberrations that lead to morphologically similar mature anomalies. The ability of developmental processes to heal themselves, as shown experimentally, may obscure the true mechanism and timing of occurrence although the final morphological expression may be dramatic. Since the study of human embryogenesis in the experimental laboratory is ethically unacceptable although technically feasible, the elucidation of the mechanisms of these neural defects will be long in coming.

Genetic spina bifida occulta in the mouse

Spina bifida occulta is one of the major effects of the recessive mutant "snubnose" (symbol sno). Linkage tests have located this mutant in chromosome 4. Defective spinal arch formation typically includes the lumbar and often the posterior thoracic and sacral vertebrae. There is great variation in detail, from nearly normal closure to a trough-like spinal column. Causes of the variation are not understood. Severely affected specimens may also have defective anterior thoracic vertebrae and reduced size of the sacral vertebrae, with kyphosis. The tail is essentially normal. No external lesion or myelomeningocele has been found, but there have been some instances of paralysis of the hind limbs, possibly from injury. The spinal cord seems normal as a rule, and pigmentation is normal. Embryological study has not been attempted, but the condition seems to be primarily osteogenic in origin.

Performance of children with spina bifida manifesta on the Frostig Developmental Test of Visual Perception

Children with spina bifida manifesta have been described as having a higher than average probability of visual-perceptual impairment. However, documentation with standardized test instruments of visual-perceptual functioning observed for this group has been meagre. In the present study, approximately 60% of Ss examined failed to show age-appropriate performance on the Frostig Developmental Test of Visual Perception. Performance on the Frostig test was analyzed for these Ss in relation to level of spinal cord lesion, presence or absence of hydrocephalus, age, IQ. Possible causal bases for visual-perceptual impairment in these children and implication for training are discussed.

'Meningoceles' and 'meningomyeloceles' (ectopic spinal cord). Clinicopathological basis of a new classification

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