Pediatric Neurosurgery

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.

This is a retrospective review of all closed-head injured children, ages 1–36 months, admitted to the Children’s Memorial Hospital from 1959 to 1978. Injuries ranged from trivial to those producing deep coma. A coma scoring system (to correlate level of consciousness with age and outcome) was devised. Lateralizing neurological signs, fontanelle status, retinal hemorrhages, seizures, and skull fractures were correlated with age, outcome, and late onset of seizures. Children of 1 year and younger were more prone to have a poor outcome in all coma grades except the deepest, where the trend <i>apparently </i>reversed. Of the three components of the coma score (ocular, motor, verbal) the ocular score more constantly reflected neurological damage. Subdural hematomas, which were largely responsible for poorer outcomes in infants, occurred almost exclusively in children under 1 year of age. Lateralizing neurological signs, which were not found to correlate directly with a poor outcome, were unilateral Babinski, ataxia, and the combination of ocular deviation and hemiparesis (which is probably a seizure variant). Hemiparesis alone, however, did correlate directly with a poor outcome, as did full, and especially tense, fontanelle, and split sutures or diastatic fractures. Linear fractures, when unilateral, were not associated with a poor outcome, although bilateral linear and depressed fractures were. Bilateral retinal hemorrhages were found to be both quantitatively and qualitatively different from unilateral retinal hemorrhages, and to be statistically more often associated with subdural hematoma.

A wide variety of surgical adjuvants to the standard bony decompression have been advocated in the treatment of the Chiari I malformation, especially when the tonsillar herniation is associated with hydrosyringomyelia. These include various shunting procedures, duroplasty, obex plugging, and resection of the cerebellar tonsils. Our practice has been to avoid these adjuvants and to perform a simple limited occipital craniectomy, C₁ laminectomy, and dural opening. The dura mater is left open and overlain with oxidized cellulose. To evaluate the efficacy of this more limited procedure, a retrospective review was performed of the medical records of 31 consecutive patients treated over a 6-year period. Twenty-six (84%) of these patients had an associated spinal cord syrinx; all underwent the same procedure. The follow-up period ranged from 15 to 93 months, with all patients having at least one postoperative magnetic resonance imaging at 6 months. Twenty-three of the 26 patients (88%) who presented with a syrinx had significant resolution of the syrinx on follow-up scans with concomitant improvement of presenting signs and symptoms. Of the remaining 3 patients, 1 had progressive hydrocephalus and received a ventriculoperitoneal shunt, with symptom resolution. In the other 2 patients the syrinx did not diminish; both received syringopleural shunts. Postoperative morbidity includes a 26% incidence of headaches, of which half resolved within 5 days, and only 1 persisted beyond 2 weeks. Nausea and vomiting occurred in 16%. Neither of these figures significantly exceeds those of other large surgical series in which the dura mater was closed with a patch graft. Three patients (10%) did have a postoperative cerebrospinal fluid leak; all responded to bedside suturing without further sequelae. This study indicates that a simple bone removal and open dural decompression of the cervicomedullary junction is a safe, effective operative treatment for Chiari I malformation in children. Shunts, duroplasty, obex plugging, and tonsillar resection offer no benefit regarding the outcome when our series is compared to others in which such adjuvants were used.

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>Objective:</i> The majority of children with posterior fossa tumors have hydrocephalus (HC) at the time of presentation. There is no consensus regarding the management of HC in these children. Here, we report the rate of cure of HC with tumor surgery alone. <i>Patients and Methods:</i> This is a retrospective study of 87 children with posterior fossa tumors in which 35 patients had medulloblastoma, 38 had astrocytoma and 14 had ependymoma. The mean age at presentation was 7.3 years (range: 0.2–19.7 years). All patients underwent tumor resection and were followed with close clinical and image surveillance to detect persistent HC. HC was treated with endoscopic third ventriculostomy (ETV) or shunt. We have focused on patients who needed permanent cerebrospinal fluid diversion (ETV or shunt) within 30 days of tumor resection. HC presenting after this time period is, in the majority of cases, due to tumor recurrence or progression. In this series, 24/87 (28%) patients had a suboccipital craniectomy and 63/87 (72%) had a craniotomy. <i>Results:</i> At the time of presentation, 69/87 (79%) patients had symptomatic HC. In 41/69 (59%) patients presenting with HC, the HC was cured by tumor resection alone. The HC cure rate for patients with astrocytoma was 83%, whereas it was 47% for patients with medulloblastoma and 54% for patients with ependymoma. The cure rate was equal in the craniectomy and craniotomy groups. <i>Conclusions:</i> An 87% cure rate of HC by tumor resection alone in children with posterior fossa astrocytoma warrants no change in treatment strategy. However, the low cure rate of HC by tumor resection alone in patients with medulloblastoma and ependymoma raises the issue of whether these patients would benefit from preresection ETV.

<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.

Endoscopic third ventriculostomy (ETV) for obstructive hydrocephalus has a failure rate of 20–50% in various series. The present study analyzes ETV failures in 72 patients over a 2-year period and attempts to outline a management plan. Of the 72 patients who underwent ETV, it failed in 13. Seven of these failures occurred within 1 month, and in 5 others, ETV failed after 1–2 months. Another patient had a delayed failure 2 years after the initial surgery. Upon clinical failure, MRI scans were performed in all patients using either T2 fast spin echo or two-dimensional phase contrast MRI techniques. Of these, no flow could be demonstrated in 12 patients, whereas in 1 patient, good flow was observed. Endoscopic exploration was undertaken in the 12 patients in whom flow could not be demonstrated. Of the 12 who underwent endoscopic exploration, a patent stoma was observed in 7, necessitating insertion of a ventriculoperitoneal shunt (VPS). In the other 5, the stoma had closed by gliosis and a repeat ETV was performed. In 3 of these patients, in addition to the ETV, a VPS was also inserted in accordance with the family’s wishes. VPS insertion was carried out in the patient with suggestion of good flow through the stoma. In failed ETV, MRI with flow studies is essential to identify the possible cause of failure. Endoscopic exploration is indicated for patients with no evidence of flow. A repeat ETV is indicated in patients with a closed stoma. Patients with a patent stoma could require insertion of a cerebrospinal fluid shunt.

<i>Background:</i> Temporal lobectomy in adults is an accepted form of treatment for patients with intractable complex partial seizures. There have been few long-term studies of children undergoing temporal lobectomy for epilepsy. <i>Methods:</i> We reviewed the pediatric cases of temporal lobectomy for intractable epilepsy performed by the Comprehensive Epilepsy Program at the University of Alberta Hospitals between 1988 and 2000. All patients had preoperative and postoperative clinical evaluations, seizure charts, drug levels, EEG, CT/MRI, long-term video EEG monitoring and neuropsychological testing. The patients were reassessed at 6 weeks, 6 months and 1 year postoperatively, then yearly. The duration of follow up was 1–10 years (mean 5 years). <i>Results:</i> Forty-two patients were studied (25 males and 17 females). Age at surgery ranged from 18 months to 16 years. The interictal EEG was abnormal in 38 of the 42 patients. Twenty-two patients had focal epileptic discharge and 1 had generalized epileptic discharge. Focal slowing was seen in 9 patients and diffuse slowing in 5 patients. CT scan was abnormal in 17 of 39 patients and normal in 22 of 39. MRI was abnormal in 34 of 42 patients and normal in 8 of 42. Pathology included brain tumors in 14 patients, mesial temporal sclerosis in 8, focal cortical dysplasia in 4, tuberous sclerosis in 4, dual pathology in 4, porencephalic cyst in 1 and normal pathology or gliosis in 6. Thirty-three of 42 patients (78%) were seizure-free following surgery and an additional 5 (12%) had a decrease in seizure frequency. Three patients had complications, but there were no deaths. <i>Conclusion:</i> Temporal lobectomy is a safe and effective treatment for children with intractable complex partial seizures. Seventy-eight percent of patients are seizure-free following the surgery and there are few complications. MRI is superior to CT scan for detection of temporal lobe pathology yet failed to detect abnormalities in some patients. The most common pathologies found were brain tumors, mesial temporal sclerosis and developmental lesions. In addition to seizure control, many patients experienced improvement in cognitive and psychosocial function following surgery.