Sylvester H. Chuang

MEG predicts epileptic zone in lesional extrahippocampal epilepsy: 12 pediatric surgery cases.

Summary:  Purpose: To discover whether the spatial distribution of spike sources determined by magnetoencephalography (MEG) provides reliable information for planning surgery and predicting outcomes in pediatric patients with lesional extrahippocampal epilepsy.

Temporal lobe surgery for intractable epilepsy in children: an analysis of outcomes in 126 children.

OBJECTIVETemporal lobectomy is a well-established neurosurgical procedure for temporal lobe epilepsy. In this study, we conducted a retrospective review of children with drug-resistant temporal lobe epilepsy to evaluate seizure outcome after temporal lobe surgery. METHODSWe reviewed the medical records of 126 children who had surgery for temporal lobe epilepsy at The Hospital for Sick Children between 1983 and 2003. The records were examined for preoperative and intraoperative factors that could predict patient outcome after surgery. RESULTSThe mean age at seizure onset was 5.9 years. The mean seizure duration before surgery was 5.6 years. All patients had preoperative computed tomographic scans, magnetic resonance imaging scans, or both. The mean age at the time of surgery was 13.5 years. Sixty-two patients underwent left temporal resections and 64 patients underwent right temporal resections. The histopathology of the temporal resections revealed low-grade brain tumors in 65 children (52%) and cavernous malformations in four children. Ganglioglioma and astrocytoma were the most common tumors encountered. Mesial temporal sclerosis was found in 16 patients (13%), astrogliosis in 15 patients (12%), and cortical dysplasia in eight patients (7%). Postoperative follow-up of at least 2 years was available for 106 patients and ranged up to 13.0 years. Seventy-four percent of patients had an Engel Class I or II outcome. Patients with temporal lobe lesions had better outcomes compared with those without lesions (P < 0.05). Patients without a history of secondary generalization of seizures also had a better outcome when compared with those with secondary generalization. Complications in the form of contralateral homonymous hemianopsia, dysphasia, and infection were found in 5% of patients. Twelve patients had a second temporal lobe procedure for intractable recurrent seizures. After a second procedure, seven patients returned to a seizure-free state. CONCLUSIONTemporal lobe resections for epilepsy in children are effective and safe procedures, with a favorable impact on seizure control. Repeat temporal resections for recurrent seizures may also be effective in restoring a seizure-free outcome to children.

Intracranial Meningiomas in Children

Thirteen cases of intracranial meningioma presenting in childhood were encountered at the Hospital for Sick Children in Toronto over a 51-year period. The clinical features, radiology, operative findings and outcome are reviewed.

Characterizing Magnetoencephalographic Spike Sources in Children with Tuberous Sclerosis Complex

Summary:  Purpose: Tuberous sclerosis complex (TSC) often causes medically intractable seizures. Magnetoencephalography (MEG) localizes epileptiform discharges. To evaluate the use of MEG spike sources (MEGSSs) for localizing epileptic zones in TSC patients, we characterized MEGSSs and correlated them to EEG and magnetic resonance imaging (MRI) results.

Evaluation of subcortical white matter and deep white matter tracts in malformations of cortical development.

Summary:  Aims: Abnormal cortical development will lead to abnormal axons in white matter. The purpose was to investigate (1) the microstructural changes in subcortical white matter adjacent to malformations of cortical development (MCD) and (2) the deep white matter tracts using diffusion tensor imaging (DTI).

Characteristics of MEG and MRI between Taylor's focal cortical dysplasia (type II) and other cortical dysplasia: surgical outcome after complete resection of MEG spike source and MR lesion in pediatric cortical dysplasia.

PURPOSE Cortical dysplasia (CD) has been classified as Taylors focal cortical dysplasia (FCD type II) or other CD (FCD type I and mild malformation of cortical development) based on histological findings. The aims of this study were to determine whether MRI and magnetoencephalography (MEG) could distinguish between these two groups and to evaluate surgical outcomes. METHODS We evaluated the MRI features, MEG spike source (MEGSS) patterns (clusters or scatters) and postsurgical seizure outcomes of 27 children with CD. RESULTS Thirteen patients had Taylors FCD and 14 had other CD. MRI showed visible lesion in 22 (81%) patients. Tapering of abnormal white matter signals to the ventricles and cortical thickening were more prevalent in Taylors FCD; focal hypoplasia and white matter atrophy were more prevalent in other CD. MEG showed spike sources in 26 (96%) patients. Taylors FCD showed clustered MEGSSs in 6, both clustered and scattered MEGSSs in 5 and scattered MEGSSs in 2; other CD demonstrated clusters in 2, cluster and scatter in 10 and scatter in 1. Eleven (85%) of 13 patients who had complete resection of clustered MEGSSs achieved Engel class I outcome, but 4 (44%) of 9 patients with incomplete resections achieved class I. Fifteen (88%) of 17 patients who had complete resection of MRI lesions achieved class I, but 1 (33%) of 3 patients with incomplete lesionectomy was class I. There was no difference in surgical outcomes between Taylors FCD and other CD. CONCLUSIONS Surgical outcome was the same in both groups following complete removal of areas containing clustered MEGSSs and MR lesions.

Recurrent Intractable Seizures in Children With Cortical Dysplasia Adjacent to Dysembryoplastic Neuroepithelial Tumor

The purpose of this study was to identify the pathologic features that predict postoperative outcome in children with cortical dysplasia adjacent to dysembryoplastic neuroepithelial tumors. We reviewed the records of children with dysembryoplastic neuroepithelial tumor who underwent epilepsy surgery and who had at least 1 year of surgical follow-up. We divided the dysembryoplastic neuroepithelial tumors into three pathology classes (simple, complex, and nonspecific), categorized adjunctive cortical dysplasia into four types, and compared histopathology with seizure outcomes. We identified 26 children with dysembryoplastic neuroepithelial tumors. Dysembryoplastic neuroepithelial tumors were complex in 19 patients (73%), simple in 6 (23%), and nonspecific in 1 (4%). Cortical dysplasia was adjacent to dysembryoplastic neuroepithelial tumors in 18 patients. Six patients had type IA cortical dysplasia, 5 had type IB, 3 had type IIA, and 1 had type IIB. The 3 remaining patients had repeated surgeries; of these, 2 patients had cortical dysplasias of type IA/IB and 1 was type IIA/IIB. Eight (39%) of 18 patients with dysembryoplastic neuroepithelial tumors and cortical dysplasia required further surgery for recurrent intractable seizures (P < .05), whereas none of 8 patients without cortical dysplasia required additional surgery. Of 13 patients with type I cortical dysplasia, only 4 had a poor seizure outcome, whereas all 5 patients with type II had a poor seizure outcome postoperatively (P < .05). Children with dysembryoplastic neuroepithelial tumor and cortical dysplasia often had recurrent intractable seizures postoperatively and required further epilepsy surgery. Cortical dysplasia adjacent to dysembryoplastic neuroepithelial tumor can play a role in the epileptogenicity of dysembryoplastic neuroepithelial tumor. Complete resection of a dysembryoplastic neuroepithelial tumor and its adjacent cortical dysplasia should be considered. (J Child Neurol 2005;20:377—384).

Myxopapillary Ependymoma of the Filum Terminale and Cauda Equina in Childhood: Report of Seven Cases and Review of the Literature

Seven of fourteen children with spinal cord ependymoma had myxopapillary tumors of the filum terminale. These tumors made up 15.9% of all primary spinal neuroectodermal tumors in children (44 cases) seen during a 62-year period (1919 to 1981). Their clinical presentation, radiological features, pathological findings, treatment, and outcome are reported. Six of the seven patients were known to be alive at the time of writing. The seventh patient was lost to follow-up after 3 years without tumor recurrence. Of 5 patients whose primary mode of treatment was operation alone. 3 had intraspinal or intracranial recurrences. Despite tumor recurrences, 2 patients were long term survivors after further operation and irradiation, whereas the third patient recently received craniospinal irradiation for intracranial tumor recurrence. The 2 patients who did not have tumor recurrence after operation alone had been followed for 3 and 7 years, respectively. Two children with subtotal tumor resection and spinal irradiation had no recurrences at 1 and 17 years, respectively. Our data suggest that this unusual subtype of spinal ependymoma is not uncommon during childhood and has a good prognosis. All patients with this tumor require prolonged follow-up for tumor recurrence after operation and irradiation.

MR evaluation of the temporomandibular joint in juvenile rheumatoid arthritis.

Temporomandibular joint (TMJ) disease is uncommon in children but frequently occurs in juvenile rheumatoid arthritis (JRA). Involvement is often asymptomatic; however, it can lead to growth disturbances and facial deformity. Thirty TMJs in 15 children (11 girls and 4 boys aged 3.5–18 years) with JRA were evaluated clinically and by MRI. Plain films were reviewed when available. Magnetic resonance imaging parameters included T1-weighted and in some cases T2-weighted or gradient recall echo sequences. We assessed condylar configuration, glenoid fossa changes, presence of erosions, disk abnormality, range of motion, and presence of joint effusions or pannus. Abnormalities included cortical erosions (n = 19), disk thinning (n = 18), and perforation (n = 2). Reduction of joint movement (n = 20), joint locking (n = 3), and pannus/effusions (n = 5) were also found. Magnetic resonance imaging is a useful technique for the detection of TMJ involvement in JRA. Early detection and therapeutic intervention may lessen or prevent subsequent deformities.

Sound motion evoked magnetic fields

OBJECTIVE The aim of present study was to determine which brain regions are involved in the conscious perception of sound motion in humans. METHODS Six kinds of sound stimuli were studied. Two static sound stimuli with durations of 100 or 1000 ms remained at a fixed position during the stimulation period. Four moving sound stimuli with duration of 100 or 1000 ms were moving from left to right, or right to left, during the stimulation period. Evoked magnetic fields were recorded using a 151-channel whole cortex magnetoencephalographic system. RESULTS The response identified in all sound stimuli was M100. Responses identified only in moving sound stimuli were M180, M280 and M680. Contour maps and dipoles overlapped on magnetic resonance imaging indicated that both the M100 and M680 responses were generated in the superior temporal cortex (left and right), while M180 and M280 were generated in the parietal cortex (right). CONCLUSIONS The results of this MEG study indicated that the right parietal cortex was involved in sound motion processing. We hypothesize that the right parietal cortex, in association with the left and right superior temporal cortex, forms a network to process sound motion information.