Myelocele: rupture of the neural tube?

A unique case of split cord malformation type 1 with three different types of bony spurs

Split cord malformation (SCM) is a rare congenital anomaly. The presence of bony spurs seen in type 1 SCM are usually partial and unequivocally are found attached to the dorsal surface of the vertebral body. We present here a unique case of SCM where the bony spur was found attached to the ventral aspect of the posterior arch and there were three different types of spurs (Type 1A, 1B and 1C) in the same patient.

Duplicate filum terminale noted in an adult: a rare finding

This is the first reported case of an adult presenting with tethering symptoms, limb discrepancy on physical examination, a low-lying spinal cord, and duplicate filum terminale discovered intraoperatively. Intraoperative imaging and pathological analysis of a specimen confirmed the diagnosis of duplicate filum. This is the first reported adult case with duplication of the filum terminale. Release of both fila was necessary in this case to relieve the tethering symptoms.

A rare case of type 1 C split cord malformation with single dural sheath

Split cord malformation (SCM) is a rare congenital anomaly in which the cord is split over a portion of its length to form double dural tubes (SCM type I) or two hemicords in a single dural sheath (SCM type II). Dachling Pang classified SCM into 2 types with type I SCM consisting of two hemicords, each contained within its own dural sheath and separated by rigid osseocartilaginous median septum. We report a rare case of SCM type 1 c in which there was a single dural sheath.

Duplicated filum terminale in the absence of split cord malformation: a potential cause of failed detethering procedures

INTRODUCTION

A duplicated filum terminale appears to be a rare finding in the absence of a split cord malformation. Herein, we discuss this finding and its potential dysembryology.

CASE REPORTS

We report two cases of duplicated filum terminale without split cord malformation. The first case presented as an incidental finding with thickened filum terminale. At time of surgery, a thickened filum was resected and a smaller size filum was transected and both were confirmed with pathologic examination. The second case presented with a lumbar skin hemangioma. Screening MRI showed a duplicated filum terminale with fat signal in both structures. Pathology also confirmed the diagnosis of two fila terminalia.

CONCLUSIONS

The neurosurgeon should consider the possibility of two fila terminalia during operation to transect a single filum for tethered spinal cord.

Myelomeningocele: a progressive intra-uterine disease

A series of cats were made hydrocephalic by intracisternal injection of kaolin, and four weeks later ventriculography confirmed the presence of hydromyelia. Ten days later, laminectomy in the lower thoracic region was performed. Several days later ventriculography revealed a markedly dilated central canal beneath the entire laminectomy, and pathological examination confirmed the presence of a focal bulge confined to the same region. On sectioning, it was evident that the central canal was massively enlarged to fill the entire spinal cord beneath the bulging region. The conclusion from these findings is that myelomeningocele is the result of progressive intra-uterine disease which begins with pathological hydromyelia and culminates in rupture of the unsupported spinal cord as a result of maldevelopment of associated dermal tissue.

Neural tube defects

Defects of development of the neural tube can result in a number of seemingly different malformations. Understanding the abnormal embryology helps one understand the malformations and their surgical treatments. The clinical presentations and the follow-up of these patients require attention to various end organs besides the nervous system. For most of these conditions, long-term follow-up is necessary regardless of initial treatment. A decline in function is not a part of the natural history of these malformations and requires prompt evaluation and treatment.

[Symptomatic Chiari type II malformation]

The Chiari type II malformation is the leading cause of death in infants with myelomeningocele. The authors report 17 cases of symptomatic Chiari type II malformation occurring in two distinct age dependent population. In Group I, 13 neonates and infants in the first year of life presented with cranial nerve and brain stem dysfunction characterized by vocal cord paralysis, apnea, dysphagia and laryngeal stridor. In Group II, 4 patients developed signs and symptoms after the first year of life. In this group, the presentation was more insidious and included neck pain and cerebellar manifestations. The surgical treatment consisted initially in shunt implantation or revision and when there was no improvement, posterior fossa decompression was performed. The response to the surgical treatment differed considerably between the two groups: older patients improved promptly after surgery and there was no casualties; in newborn and infants, especially those under 6 months of age, the mortality rate was 46.1%. The authors stress that prompt diagnosis and surgical intervention should be performed in order to produce a favorable outcome.

The Chiari malformations: a constellation of anomalies

The Chiari malformations form a group of abnormalities that are pathogenetically interrelated. The most important member of the group is the Chiari type II malformation, known as the Arnold-Chiari malformation. Its cardinal features are the myelomeningocele in the thoraco-lumbar spine, the venting of the intracranial cerebrospinal fluid through the central canal, the hypoplasia of the posterior fossa, the herniation of hindbrain into the cervical spinal canal, and the compressive damage to cranial nerves. Some of the abnormalities are progressive, and thus treatable. Limitation of progression may improve outcomes. The challenges to our treatment programs involve early diagnosis, delivery by Caesarean section, emergent closure of the neural plaque and prophylaxis of hydrocephalus, anticipatory prevention of the neurological compression syndromes, multidisciplinary teams, and age-appropriate interventions.

Evaluation of tethered cord syndrome associated with anorectal malformations

The clinical courses of four patients with occult spinal dysraphism who were also found to have anorectal malformations and tethered cord syndrome are evaluated in this report. These patients were among 27 patients with occult spinal dysraphism treated in the Division of Neurosurgery of Tohoku University School of Medicine during the last 3 years. All four patients experienced urinary disturbances early in life, and initially, these disturbances were considered to be caused by urogenital malformations. As a result, treatments were delayed. Only one patient with male Turner's syndrome exhibited mental retardation. Other symptoms, such as sensory disturbance and pain in the lower extremities, became apparent from complaints by the patients without atresia ani. When surgery was performed earlier in our patients with occult spinal dysraphism, the outcome was better. We believe in early surgery for tethered cord syndrome, although there is no consensus for the timing of this surgery. Unfortunately, the diagnosis of tethered cord syndrome was delayed in our four patients. However, because occult spinal dysraphism and anorectal malformations seem to be closely related, the presence of anorectal malformations may result in an earlier diagnosis of tethered cord syndrome.

Chiari malformation with syringocephaly. Case report

A 69-year-old white woman presented with a left hemiparesis which progressed to quadriparesis and encephalopathy. Computerized tomography and magnetic resonance imaging revealed a Chiari I malformation and a hydromyelic cavity extending from C-2 to T-6. Rostrally, the cavity extended through the ventral medulla, pons, and right cerebral peduncle into the right cerebral hemisphere, where the cavity enlarged and was associated with mass effect. The patient has made a dramatic neurological recovery following suboccipital craniectomy with insertion of a dural graft to decompress the Chiari malformation and upper cervical laminectomy and dorsal root entry zone myelotomy to decompress the hydromyelia.

Symptomatic Chiari malformations. An analysis of presentation, management, and long-term outcome

The Chiari malformation is a condition characterized by herniation of the posterior fossa contents below the level of the foramen magnum, and is categorized into three types based on the degree of herniation. The authors review their surgical experience between 1975 and 1985 with 50 patients afflicted with symptomatic Chiari malformations. Any patient with associated myelomeningocele, tethered spinal cord, lipoma, or diastematomyelia was excluded from this series. Forty-one patients had Chiari I malformations, seven were classified as having Chiari II, and two as having Chiari III. The presentation of pediatric and adult patients was identical. Treatment was directed at the posterior fossa pathology. Seven patients with accompanying ventral bone compression underwent transoral decompression of the cervicomedullary junction, 42 had posterior decompressive procedures, and six received ventriculoperitoneal shunts. The posterior decompression included opening the outlet foramina of the fourth ventricle, occluding any communication between the spinal cord central canal and the obex, shunting the fourth ventricle, and placing a dural graft. Postoperatively, 20% of the patients are asymptomatic, 66% improved, and 8% stabilized; in 6% the disease has progressed in spite of multiple procedures. Preoperative signs that are predictive of a less favorable outcome include muscle atrophy, symptoms lasting longer than 24 months, ataxia, nystagmus, trigeminal hypesthesia, and dorsal column dysfunction (p less than 0.05, chi-square test). A model based on the presence or absence of atrophy, ataxia, and scoliosis at the time of the preoperative examination has been generated that allows prediction of long-term outcome at the 95% confidence level.

Experimental hydrocephalus and hydrosyringomyelia in the cat. Radiological findings

Fourty-six cats were made hydrocephalic and hydromyelic by means of an intracisternal kaolin injection. In 17 other cats hydrocephalus and syringohydromyelia were achieved by operative occlusion of the foramina Luschkae of the fourth ventricle. In both the kaolin treated animals and the animals whose outlets of the fourth ventricles were operatively obstructed a progressive dilatation of the ventricles and central canal occurred, which could be demonstrated and followed in 30 animals by ventriculography, myelography and/or contrast filling of the hydromyelic central canal. Coinciding with the dilatation of the central canal the clinical picture of a raised intracranial pressure due to obstructive hydrocephalus improved. The presented results suggest that the dilated central canal acts as a kind of natural by-pass between the ventricles and the spinal subarachnoid space. In order to determine the role of spinal kaolin arachnoiditis on spinal cyst formation and central canal dilatation in 13 animals, kaolin was locally applied in the lower thoracic region. The local spinal kaolin arachnoiditis had no influence on central canal dilatation or cyst formation.

Chromosome translocation (T(2;4)1 Sn)-induced neural tube defects in the mouse embryo

Neural tube closure was studied in embryos obtained from matings of male mice heterozygous for a reciprocal chromosome translocation (T(2;4)1 Sn) with normal female (CFLP) mice. When litters were examined on the 9th to 12th days of gestation, there was a high incidence of resorption, developmental delay and neural tube closure defects in these embryos. SEM observations indicated that the neural tube closure defects ranged in severity from a side-to-side flattening of the midbrain to extensive anomalies in which the entire cephalic neural tube had failed to close. In addition to cephalic defects, a number of embryos exhibited open defects or abnormal subectodermal blebbing in the future lumbosacral region. In spinal regions, even in areas in which the neural tube had previously closed, it often was irregular and folded. These observations are discussed in relation to studies of gene-related defects of neural tube closure.

[Incidental syringohydromyelography: report of a case]

The radiological findings of syringomyelography are described in a five years old patient who underwent a percutaneous injection of opaque contrast medium (Lipiodol) into the intraspinal syringomyelic cavity. The clinical picture, the usual diagnostic methods and the place of syringomyelography for the diagnosis of syringomielia are discussed.

Vertical hydrocephalus: report of three cases

Three cases of 'vertical' hydrocephalus are described, characterised by absence of the bones of the skull vault, progressive vertical soft-tissue growth of the head, and normal occipito-frontal head circumference. The management of the condition by ventriculo-peritoneal shunt is discussed, and a theory proposed as to the causation of this unusual condition.

Scoliosis and hydrocephalus in myelocele patients. The effects of ventricular shunting

Developmental scoliosis is a common cause of increasing disability and deformity in long-term myelocele survivors, and is believed to result from a paralytic collapsing spine. The possible etiological role of compensated hydrocephalus and hydromyelia was assessed by determining the effect of ventricular shunting on 11 myelocele patients with developmental scoliosis. After successful shunting, one patient with a 47 degrees curve continued to deteriorate. Three cases with curves greater than 60 degrees were stabilized for short periods, but eventually required spinal fusion. Seven cases with curves less than 55 degrees were improved from a mean scoliosis of 29 degrees to 13 degrees during a 20-month follow-up period. Several patients had pre-existing shunts that were found to be non-functional on shuntogram. These findings suggest that the spinal complications of hydrocephalus may be more common than previously recognized in myelocele patients and that advanced developmental scoliosis may be avoided by early recognition and ventricular shunting.

Syringomyelia following lumboureteral shunting for communicating hydrocephalus. Report of three cases

Three patients are described in whom syringomyelia was identified long after the treatment of communicating hydrocephalus by a lumboureteral shunt. The reason for syrinx formation in these cases could not be determined. In two there was either autopsy-proven or presumed evidence for arachnoiditis, and in the third patient the symptoms of syringomyelia were acutely aggravated by temporary obstruction of shunt. The development of a pressure drop from the intracranial compartment to the spinal compartment with crowding at the foramen magnum is also a suggested mechanism.

Microsurgery of Arnold-Chiari malformation in adults with and without hydromyelia

Microsurgical exploration of 15 adults with Arnold-Chiari malformation with and without hydromyelia using 3 to 20 X magnification has led to the following conclusions. Hydromyelia, associated with Arnold-Chiari malformation, is a progressive mechanical disorder that causes spinal cord deficits by pressure distention of the cord. Arnold-Chiari malformation causes slowly or suddenly progressive bulbar dysfunction by impaction of the malformation in the foramen magnum. Decompression of both can be achieved by a suboccipital carniectomy, upper cervical laminectomy, establishing an outlet from the fourth ventricle, and opening the distended cord in the thinnest exposed area, which is usually along the dorsal root entry zone. If Pantopaque myelography in patients in the supine position shows the Arnold-Chiari malformation, hydromyelia can be established as a cause of central cord deficit even if myelography shows the cord size to be normal. Syringomyelia, traditionally considered a degenerative disease, is a less common cause of a slowly progressive central cord deficit than either hydromyelia or intramedullary tumor.

Clinical radiosotope investigations in hydrosyringomyelia and myelodysplasia

Radioisotope ventriculography was applied clinically in myelodysplastic hydromyelia in three groups of patients: two patients with normal ventricles, two with obstructive hydrocephalus, and 16 with myelodysplasia. In the myelodysplastic group, radioassay in one patient demonstrated flow of radioistope down the hydromyelic cavity. Twenty scintigraphic studies on 16 myelodysplastic patients showed hydromyelia was present in all patients with spontaneously compensated hydrocephalus but in none of those with functional ventricular shunts. This relation between the hydromyelia and disordered ventricular hydrodynamics supports the Gardner hypothesis of myelodysplasia. Radioisotope ventriculography appears a safe and useful method of diagnosing hydrosyringomyelia and evaluating treatment by means of ventricular decompression.

Micro- and macrovascular changes as the direct cause of parenchymal destruction in congenital murine hydrocephalus

Microangiotomography was used to identify the normal and pathological pattern of cerebral vessels in the hy-3 murine mutant mouse (normal and hydrocephalic) at various developmental stages from birth through 21 days of life. The technique employed allows resolution, in the range of 7 to 10 mu of the surface and intraparenchymal (perforating) microvasculature. Ventricular enlargement causes displacement of primary cerebral arteries, followed by both stretching and a decrease in the caliber of primary, secondary, and tertiary vessels (arterial and venous). Ultimately, there is a reduction in the number and caliber of the microvasculature, resulting in diminished cerebral blood flow and cerebral edema. Tissue destruction leading to ependymal rupture, parenchymal cavitation, and the formation of porencephalic cysts within the edematous parenchyma ensues. External ventricular drainage, by decompressing the ventricles, resulted in rapid restoration of the filling of the primary and secondary vessels, thereby suggesting the primary role of vascular changes in the production of brain damage. This study offers experimental evidence that early diversion of the cerebrospinal fluid interrupts this chain of events in congenital murine hydrocephalus.

Meningomyelocele and progressive hydromyelia. Progressive paresis in myelodysplasia

Five cases of myelodysplasia with progressive paraparesis are presented. Three of the five patients developed spasticity, but dissociated sensory loss and loss of sphincter control was not a prominent feature. All were found to have compensated hydrocephalus and extensive communicating hydromyelia. The use of myelography and ventriculography in the diagnosis of hydromyelia is discussed. Ventricular drainage led to clinical improvement in two cases and radiological improvement in one. The relationship of compensated hydrocephalus, meningomyelocele, and progressive hydromyelia postnatally may support the hydrodynamic hypothesis of myelodysplasia.

Experimental hydrosyringomyelia, ischemic myelopathy, and syringomyelia

The authors found that cavities in the spinal cord of dogs appearing after the intracisternal administration of kaolin are not due to ischemic softening, but rather to distention and subsequent rupture of the central canal. Ischemic lesions could be produced and were found to have a quite different histopathology; this supports the hydrodynamic hypothesis of cavitary myelopathy following adhesive arachnoiditis, probably as a compensatory mechanism to the associated hydrocephalus. The similarities to human syringomyelia are discussed.

The relationship of Arnold-Chiari and Dandy-Walker malformations

✓ The posterior fossa is abnormally small in cases of Arnold-Chiari malformation because the tentorium is too low, whereas it is abnormally large in the Dandy-Walker malformation because the tentorium is too high.

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

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