Clinical radiosotope investigations in hydrosyringomyelia and myelodysplasia

Shunt malfunction presenting with symptomatic syringomyelia: Demonstrated on contrast ventriculogram

Ventriculoperitoneal (VP) shunt malfunction commonly presents as raised intracranial pressure. Rarely, when the central canal of the spinal cord communicates with the 4^th ventricle, shunt malfunction can present as an expanding syrinx. The diagnosis is often delayed, resulting in severe morbidity. Some of these patients undergo repeated syrinx surgeries without much benefits. We report a case of chronic tuberculous meningitis with shunt malfunction presenting as an expanding spinal canal syrinx and quadriparesis. Fourth ventricular communication with syrinx was demonstrated with the help of a contrast ventriculogram. After shunt revision, syrinx resolved completely and the patient made significant improvement in his neurological deficits. The present case illustrates that a historical and rarely used investigation like contrast ventriculogram aids in the diagnosis and management even in the current neurosurgical practice. All patients with late onset syrinx and a previous VP shunt need to be investigated for shunt malfunction before considering syrinx surgery. A simple shunt revision resolves the syrinx in such conditions and avoids more complex procedures like Foramen magnum decompression. Relevant literature has been reviewed; pathophysiology and management options have been discussed.

Preysyrinx state and shunt dysfunction: an underrecognized entity?

Presyrinx state is a relatively recently recognized condition. Prompt identification of this condition and appropriate treatment leads to reversal of the radiological and clinical findings with a good prognosis. Failure to identify this condition in a timely fashion leads to fully established syringomyelia. To date, presyrinx state has not been described as a feature of shunt dysfunction. One such rare case is being reported. A 14-year-old boy who was shunted for postmeningitic hydrocephalus at the age of 2 years and subsequently underwent shunt revision presented for routine follow-up and was found to have shunt dysfunction. CT scan showed panventriculomegaly and MRI studies showed panventriculomegaly with a "presyrinx" state extending from the fourth ventricle up to the thoracic region. Shunt revision led to prompt radiological reversal of the presyrinx state. This case is being reported to highlight the hitherto unreported association of shunt dysfunction and presyrinx state. The literature on presyrinx state is being reviewed with reference to the 20 cases reported earlier.

Pediatric syringomyelia

Syringomyelia was first recognized as a disease process some 400 years ago. The process of cystic dilation of the spinal cord is unpredictable and may result in a delay of many decades before the symptoms and signs of neurologic and orthopedic changes become apparent and commensurate with the observed cystic changes within the spinal cord. The syringomyelic process is usually associated with trauma, tumor, or congenital abnormalities at the craniocervical junction or along the spinal neuraxis. Several theories have been proposed as to processes involved in the development of spinal cyst formation, although none are completely compatible with the observed clinical pathology of syrinx development. Magnetic resonance imaging has markedly improved our ability to study the anatomy and natural history of syrinx formation, but to date, our understanding of the process remains imprecise. In view of the limited understanding of the pathophysiology of this disease process, it is not surprising that a variety of treatment regimens have been proposed and their efficacy remains difficult to fully evaluate.

Hydrosyringomyelia and diastematomyelia detected by MRI in myelomeningocele

Magnetic resonance imaging of the spine in 45 patients with myelomeningocele revealed hydrosyringomyelia in 24 and diastematomyelia in two. No patient at initial imaging manifested symptoms referable to hydrosyringomyelia; both patients with diastematomyelia had flaccid lower extremities. One patient developed an upper extremity monoparesis which resolved with syringo-peritoneal shunt placement; no other patient manifested symptoms or required surgery. Ventriculoperitoneal shunt malfunction produced reversible distention of the syrinx in another patient who remained asymptomatic.

Bilateral glossopharyngeal neuralgia after excision of a solitary cervico-medullary haemangioblastoma: case report

A man presenting with sleep apnoea was found to have a haemangioblastoma at the cervico-medullary junction. The associated hydrocephalus and syringomyelia resolved after excision of the tumour. Postoperatively the patient developed transient bilateral glossopharyngeal neuralgia, presumably due to surgical damages to the tractus solitarius. To the best of our knowledge this is the first reported case with transient bilateral glossopharyngeal neuralgia following resection of a haemangioblastoma of the cervico-medullary junction.

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.

Progressive spasticity and scoliosis in children with myelomeningocele. Radiological investigation and surgical treatment

Seventeen myelodysplastic patients with progressive extremity spasticity and scoliosis underwent radiological evaluation and surgical treatment. All but one were under 18 years of age at the time of surgical treatment. Duration of the clinical presentation ranged from 1 1/2 to 7 years. Metrizamide was instilled into the subarachnoid space in 12 patients, the lateral ventricle in two, and the hydromyelic cavity in three. Sequential computerized tomography scanning after intrathecal instillation of the contrast material clearly demonstrated hydromyelia in nine patients and compression of the brain stem in five. Posterior fossa decompression with plugging of the obex was performed in 12 patients, posterior fossa decompression alone in three, and ventriculoperitoneal (VP) shunting procedures in two. Of the 12 patients who underwent the obex plugging procedures, eight have shown partial or complete resolution of spasticity and an increase in motor strength with no significant postoperative complications. In contrast, posterior fossa decompression or VP shunting procedures alone have not led to a favorable neurological outcome. Hydromyelia may occur more commonly among myelodysplastic patients than previously recognized and may be treated most effectively by the obex plugging procedure.

Experimental syringomyelia: the relationship between intraventricular and intrasyrinx pressures

The influence of ventricular pressure changes on syrinx pressure was investigated in this study of experimental canine kaolin-induced syringomyelia. The pressures of the ventricles, syrinx, and cervical subarachnoid space were measured. A complete ventriculosubarachnoid block occurred in the animals with syringomyelia. The baseline syringeal pressures exceeded those of both the ventricles and the subarachnoid space. Raising ventricular pressure elevated the syringeal pressure, but aspiration of ventricular fluid did not acutely lower the pressure. These findings suggest a ventriculosyrinx valve effect that may inflate the syrinx during transient rises of intracranial pressure. A respiratory pressure pattern was found in the syrinx similar to that of the ventricles and subarachnoid space. This wave was reduced but not abolished by ligating the subarachnoid space distal to the syrinx. The arterial pulse was much diminished within the syrinx at rest. These findings indirectly support the possibility that transmission of thoracic pressures to the spinal subarachnoid space with compression of the syrinx is a principal force that enlarges the syrinx.

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.

Long-term results after ventriculoatrial and ventriculoperitoneal shunting for infantile hydrocephalus

This series of 228 patients with infantile non-neoplastic hydrocephalus who received either a ventriculoatrial (VA) or a ventriculoperitoneal (VP) shunt before 2 years of age was followed for an average of 7 years, and the results with the two types of shunt were compared. Mortality and infection rates were similar for both groups of patients, but children with VP shunts required significantly fewer revisions and had a much greater likelihood of not having any revisions during the follow-up period. Late complications occurred more frequently with VA shunts and were more serious. It is concluded that VP shunts offer significant advantages over VA systems in this population.

Size of posterior fossa in Chiari type 1 malformation in adults

The clinical and neuroradiological findings in five patients with Chiari Type 1 malformation presenting symptoms in adult life are presented. New posterior fossa ratio methods have been applied to this material. The posterior cranial fossae are demonstrated to be small, and the most significant deviation from normal gave the ratio h/Tw: posterior fossa height in proportion to Twining's line. The implications of these findings are discussed in relation to the static and dynamic factors that are operating in the development of neurological symptoms in Chiari type 1 malformation. A final discussion is given comparing the Chiari type 1 malformations to meningo-myelocele. The findings using posterior fossa ratio methods may strengthen the indications for suboccipital craniectomy in these patients.

Radiosotope evaluation of experimental hydrosyringomyelia

Kaolin-induced hydrosyringomyelia in dogs has been investigated by radioisotope ventriculography using both cerebrospinal fluid radioassay and scintigraphy. The hydromyelic central canal can be differentiated from the spinal subarachnoid space by scintigraphy, Serial studies show that hydromyelia arises rapidly to decompress the associated hydrocephalus in surviving animals. Syringomyelia, after a delayed onset, originates from the enlarged central canal. Radioisotope ventriculography may be a useful clinical aid in the diagnosis of hydrosyringomyelia.