Pediatric Neurosurgery

The authors report a case of oncocytic paraganglioma of the cauda equina in a 12-year-old girl who presented with lower back and leg pain on the right side of 6 months’ duration. Magnetic resonance imaging revealed an ellipsoidal, intradural, extramedullary mass causing cord compression at the level of L1. Total laminectomy was performed on T12 and L1, and the tumor was excised completely without difficulty despite adherence of the tumor to the spinal cord. Postoperatively, the leg pain and motor weakness were much improved. The use of electron microscopy, and the immunohistochemical demonstration of synaptophysin in this tumor, allowed a confident diagnosis of an oncocytic paraganglioma to be made. To the authors’ knowledge, this patient represents the first definite case of an oncocytic paraganglioma of the cauda equina in a child.

<i>Background:</i> Accurate fetal imaging is essential to the practice of maternal-fetal medicine. While ultrasonography has been the traditional mainstay of fetal imaging, its ability to resolve critical features of central nervous system (CNS) anatomy remains limited. As interest in intrauterine therapy for myelomeningocele has increased, so has the need for more accurate, noninvasive imaging of the CNS. Fetal magnetic resonance imaging (MRI) promises to fill the gap left by ultrasound. <i>Methods:</i> Thirty-seven MRI scans of fetuses previously diagnosed with myelomeningocele were reviewed by 2 neuroradiologists. The ability of fetal MRI to resolve the commonest CNS stigmata of spina bifida, and the incidence and extent of interobserver error, was assessed. In 4 cases, postnatal MRIs were also available. These were compared to the corresponding fetal studies. <i>Results:</i> The imaging quality with the technique used in this study was excellent, even without the use of maternal or fetal sedation. There were no complications, and the imaging times were minimal. Interobserver error was minimal with respect to the evaluation of ventricular dilatation and hindbrain herniation, but moderate in the description and location of the spinal lesion. As had previously been documented with ultrasonography, a reduction was seen in hindbrain herniation when comparing pre- and postnatal MRIs. <i>Conclusion:</i> It is concluded that fetal MRI is an effective, noninvasive means of assessing fetal CNS anatomy. Its ability to resolve posterior fossa anatomy is superior to ultrasonography while, with respect to the evaluation of hydrocephalus and the level and nature of the spinal lesion, it may be equivalent to inferior. Inclusion of the fetal MRI into the standard diagnostic armamentarium will probably await the next major advance in speed and resolution. It is conceivable that, with further advances, MRI might supplant ultrasonography as the diagnostic tool of choice for evaluation of fetal anomalies including myelomeningocele.

Anterior encephalocele is a rare condition, and only a few large series have been published in the literature. Surprisingly, the incidence is much higher in Southeast Asian countries, including some parts of India. While the reported incidence in the West is between 1:35,000 and 1:40,000 live births, it is as high as 1:5,000 live births in Thailand. We present a series comprising 92 cases of anterior encephaloceles treated over a 30-year period (1971–2000). Frontoethmoidal encephaloceles are the commonest type, followed by the nasopharyngeal and orbital type. Among the frontoethmoidal encephaloceles, nasoethmoid is the commonest type, and these patients present with swelling over the bridge of the nose with significant hypertelorism and orbital deformities. The nasopharyngeal type remains occult and presents with nasal obstruction or CSF rhinorrhea. Rarely, the patient may present with meningitis. Since 1978, computed tomography (CT) scans have regularly been performed in our patients. CT scans delineate the skull defect and associated brain anomalies. There was associated hydrocephalus present in 12 patients and agenesis of the corpus callosum in 5 patients. In all patients, one-stage repair of the encephalocele and correction of bony anomalies by appropriate osteotomy was undertaken. Since 1988, in cases of frontoethmoidal encephalocele with significant hypertelorism, medial advancement of the medial half of the orbits on either sides was carried out, instead of a classical Tessier’s operation. Postoperative morbidity included CSF leak in 20 patients, wound infection in 2 and chest infection in 3. There were 3 deaths in our study. The overall cosmetic outcome was good.

<i>Background:</i> Malignant transformation of pilocytic astrocytomas in children is rare and often linked to previous radiotherapy. <i>Methods and Results:</i> We report a patient who underwent subtotal resection of a right temporal and insular pilocytic astrocytoma at age 8 in 1988 followed by high-dose radiation therapy. A local recurrence, grade WHO III, with signs of focal sarcomatous transformation, was subtotally resected 13 years later in 2001. A new and fast growing right frontal meningeoma, grade WHO II, was removed in 2003. In 2004 a second glioma recurrence was partially resected, this time graded gliosarcoma WHO IV. The patient was treated thereafter with repeated courses of temozolamide. Another tumor mass reduction in 2005 was followed by stereotactic radiotherapy. Nevertheless, he deceased 3 months later. <i>Conclusion:</i> Most of the reported cases of malignant transformation of pilocytic astrocytomas received radiation therapy beforehand. Irradiation-induced meningeomas in children are known to occur, however not following radiotherapy of low-grade hemispheric gliomas. The presented case illustrates why adjuvant radiotherapy of residual pilocytic astrocytoma in children is not recommended anymore. For children who underwent radiotherapy in the past, we recommend MRI surveillance on a yearly basis far beyond 10 years, even in those who seem to have achieved total remission.

<b><i>Introduction:</i></b> The embryogenesis of limited dorsal myeloschisis (LDM) likely involves impaired disjunction between the cutaneous and neural ectoderms during primary neurulation. Because LDM and congenital dermal sinus (CDS) have a shared origin in this regard, CDS elements can be found in the LDM stalk. Retained medullary cord (RMC) is a closed spinal dysraphism involving a robust, elongated, cord-like structure extending from the conus medullaris to the dural cul-de-sac. Because the RMC is assumed to be caused by impaired secondary neurulation, concurrent RMC and CDS cannot be explained embryologically. In the present article, we report a case in which CDS elements were noted in each tethering stalk of a coexisting LDM and RMC. <b><i>Case Presentation:</i></b> A 2.5-month-old boy with left clubfoot and frequent urinary and fecal leakage had 2 tethering tracts. The upper tract, which ran from the thoracic tail-like cutaneous appendage, had CDS elements in the extradural stalk and a tiny dermoid cyst in the intradural stalk immediately after the dural entry. In the lower tract, which ran from the lumbosacral dimple, the CDS as an extradural stalk continued to the RMC at the dural cul-de-sac. Both stalks were entirely resected through skip laminotomy/laminectomy at 1 stage to untether the cord and resect the CDS elements. <b><i>Conclusion:</i></b> Surgeons should be aware that CDS elements, in addition to LDM, may coexist with RMC that extends out to the extradural space.

<b><i>Background:</i></b> An ependyma-lined canal with surrounding neuroglial tissues can be present in lumbosacral lipomatous malformations; however, the precise embryological significance is still unclear. <b><i>Method:</i></b> Six out of 50 patients with lipomatous malformations had ependymal structures. We retrospectively analyzed the clinical, neuroradiological, and histological findings of these patients to demonstrate the relationship with the embryological background of the retained medullary cord (RMC), which normally regresses, but was retained here because of late arrest of secondary neurulation. <b><i>Results:</i></b> Five (13.9%) of 36 patients with filar and caudal types and 1 of 3 lipomyelomeningoceles had ependymal structures, while none with dorsal and transitional types had these tissues. Histologically, the ependymal structures surrounded by neuroglial tissue and containing various amounts of adipose tissue bear a striking resemblance to the ependymal structures in RMC. <b><i>Conclusion:</i></b> The 13.9% incidence of association between the ependymal structures and filar and caudal types is thought to be because of second ary neurulation failure with the same embryological background as that of RMC. Dorsal and transitional types, resulting from primary neurulation failure, therefore, did not have ependymal structures.

It is well known that Down’s syndrome is sometimes associated with leukemia. However, there have been only a few case reports of a relationship between Down’s syndrome and brain tumors. We report 2 cases with histological diagnoses of germinoma. The 1st case was a 10-year-old boy with Down’s syndrome complaining of seizure and left hemiparesis. Computed tomographic (CT) scan and magnetic resonance imaging (MRI) showed a mass lesion in the right basal ganglia and thalamus. Histological examination indicated two cell pattern germinomas. The 2nd case was a 20-year-old man with Down’s syndrome complaining of headache and vomiting. CT scan and MRI showed a pineal region tumor with marked hydrocephalus. Surgical specimens showed typical germinoma. Only 13 cases of brain tumors associated with Down’s syndrome have been reported. A higher incidence of germ cell tumors seems to be related to chromosomal abnormalities.

The traditional theory of communicating hydrocephalus has implicated the bulk flow component of CSF motion; that is, hydrocephalus is generally understood as an imbalance between CSF formation and absorption. The theory that the cause of communicating hydrocephalus is malabsorption of CSF at the arachnoid villi is not substantiated by experimental evidence or by physical reasoning. Flow-sensitive MRI has shown that nearly all CSF motion is pulsatile, and there is substantial evidence that hyperdynamic choroid plexus pulsations are necessary and sufficient for ventricular dilation in communicating hydrocephalus. We have developed a model of intracranial pulsations based on the analogy between the pulsatile motion of electrons in an electrical circuit and the pulsatile motion of blood and CSF in the cranium. Increased impedance to the flow of CSF pulsations in the subarachnoid space redistributes the flow of pulsations into the ventricular CSF and into the capillary and venous circulation. The salient features of communicating hydrocephalus, such as ventricular dilation, intracranial pressure waves, narrowing of the CSF-venous pressure gradient, diminished cerebral blood flow, elevated resistive index and malabsorption of CSF, emerge naturally from the model. We propose that communicating hydrocephalus is the result of a redistribution of CSF pulsations in the cranium.