Dave F. Clarke

The Prevalence of Autistic Spectrum Disorder in Children Surveyed in a Tertiary Care Epilepsy Clinic

Summary:  It is well documented that children with autistic spectrum disorder (ASD) have an increased prevalence of seizures; however, studies have not been done to evaluate the prevalence of ASD in children with epilepsy. This comorbidity is important to define as early diagnosis and intervention in some children with ASD has been shown to improve outcome.

Corpus callosotomy: A palliative therapeutic technique may help identify resectable epileptogenic foci

Corpus callosotomy has a long history as a palliative treatment for intractable epilepsy. Identification of a single epileptogenic zone is critical to performing successful resective surgery. We describe three patients in which corpus callosotomy allowed recognition of unapparent seizure foci, leading to subsequent successful resection. We retrospectively reviewed our epilepsy surgery database from 2003 to 2005 for children who had a prior callosotomy and were candidates for focal resection. All underwent magnetic resonance imaging and scalp video electroencephalograph monitoring, and two had magnetoencephalography, electrocorticography and/or intracranial video electroencephalograph monitoring. The children were 8 and 9 years old, and seizure onset varied from early infancy to early childhood. One child had a history of head trauma preceding seizure onset, one had a large intracerebral infarct and dysplastic cortex in the contralateral frontal lobe, and the other had an anterior temporal lobe resection without improvement in seizure frequency. After medical management failed, callosotomy was performed with the expectation of decreasing the seizure types affecting both hemispheres. Following transection of the callosal fibers, a single focus was recognized and resected, with resultant dramatic improvement in seizure control. In medically refractory epilepsy, where rapid secondary bisynchrony is suspected but the electroencephalograph is non-localizing, callosotomy should be considered as a means of treating generalized seizure types, but may also assist in identifying potentially operable seizure foci. Study limitations include its retrospective nature and cohort size. The findings, however, suggest the need for prospective, systematic, well-controlled studies of the use of corpus callostomy in this intractable patient population.

Passive range of motion functional magnetic resonance imaging localizing sensorimotor cortex in sedated children: Clinical article

OBJECT In this study, the authors examined whether passive range of motion (ROM) under conscious sedation could be used to localize sensorimotor cortex using functional MR (fMR) imaging in children as part of their presurgical evaluation. METHODS After obtaining institutional review board approval (for retrospective analysis of imaging data acquired for clinical purposes) and informed consent, 16 children underwent fMR imaging. All 16 had lesions; masses were found in 9 patients and cortical dysplasia was found in 4; the lesions in 3 patients were not diagnosed. Passive ROM was performed during blood oxygen level-dependent MR imaging sequences. Three of the patients also performed active motor tasks during the fMR imaging study. All patients were evaluated using passive ROM of the hand and/or foot; 3 patients were evaluated for passive touch of the face. In 9 cases, intraoperative electrocorticography (ECoG) was used. Five of the patients underwent intraoperative ECoG to evaluate for seizure activity. Four patients had intraoperative ECoG for motor mapping. Five of the patients had subdural grids placed for extraoperative monitoring. RESULTS In 3 cases, the active and passive ROMs colocalized. In 4 patients ECoG was used to identify motor cortex, and in all 4 motor ECoG yielded results consistent with the passive ROM localization. Thirteen of 16 children have undergone resection based on passive ROM fMR imaging findings with no unanticipated deficits. CONCLUSIONS These preliminary data suggest that passive ROM fMR imaging can accurately detect functional hand, leg, and face regions of the sensorimotor cortex in the sedated child. This extends current extraoperative mapping capabilities to patients unable or unwilling to cooperate for active motor tasks.

Rapid Infusion of a Loading Dose of Intravenous Levetiracetam With Minimal Dilution: A Safety Study

Intravenous antiepileptic drugs are required in patients needing urgent treatment or unable to take oral medication. The safety of intravenous levetiracetam has been established in prospective studies of adult epilepsy and healthy participants. The authors performed a prospective, single-center study to evaluate the safety of a rapid loading dose of intravenous levetiracetam. Patients were divided into 3 equal dosing groups (N = 15 each): 20, 40, and 60 mg/kg (corresponding to maximum doses of 1, 2, and 3 g). Electrocardiogram and safety assessment were performed during the infusion. Ages were 4 to 32 years. Postinfusion serum levetiracetam concentrations were 14 to 189 μg/mL. There were no significant changes in blood pressure, no local infusion site reactions, and no electrocardiogram abnormalities. The authors concluded that high serum levels of parenteral levetiracetam can be achieved rapidly and safely, in a small infusion volume. This finding has important implications for the treatment of status epilepticus.

The Significance of Ear Plugging in Localization-related Epilepsy

Summary:  Purpose: The localizing value of ear plugging in the treatment of auditory onset partial seizures, to our knowledge, has not been previously described. We propose that ear plugging is a clinical response to a sensory seizure manifested as an auditory hallucination and a tool for identifying the seizure focus in the auditory cortex on the superior temporal gyrus.

Benign Rolandic Epilepsy—Perhaps Not So Benign: Use of Magnetic Source Imaging as a Predictor of Outcome

The purpose of this study was to evaluate children with benign rolandic epilepsy, a childhood epilepsy characterized by centrotemporal/rolandic spike-wave discharges with infrequent partial seizures that may secondarily generalize. Recently, some investigators have questioned whether benign rolandic epilepsy is indeed “benign” or whether long-term cognitive outcome may be adversely affected. We initiated an ongoing study to identify children with benign rolandic epilepsy. The children were evaluated in the Texas Comprehensive Epilepsy Program using outpatient or continuous video-electroencephalographic monitoring, brain magnetic resonance imaging, magnetoencephalography, and neuropsychological testing. Neuropsychological testing revealed fine motor dysfunction, visuomotor integration deficits, dyscalculia, and/or expressive language deficits in all of the 9 patients evaluated, reaffirming that benign rolandic epilepsy is not necessarily a benign disorder. Our study shows a high concordance of motor and cognitive deficits in benign rolandic epilepsy, as others have previously suggested. Furthermore, magnetic source imaging shows a higher resolution of dipole localization compared with conventional electroencephalography, which may ultimately improve prediction of deficits. This reaffirms that magnetoencephalography is a valuable diagnostic tool in the evaluation of children with benign rolandic epilepsy.

Angiocentric Glioma―Induced Seizures in a 2-Year-Old Child

A 2-year-old child presented with medically refractory seizures and was found to have a right frontoparietal parasagittal angiocentric glioma. Depth electrodes were used to document ictal onset from within the tumor rather than from the surrounding tissues. Ictal activity then spread to a wide area on the cortical surface, including the region around the tumor and hand motor cortex. Lesionectomy permitted sparing of adjacent areas of eloquent cortex, and the child is now seizure-free on monotherapy.

Passive language mapping with magnetoencephalography in pediatric patients with epilepsy

OBJECT Functional mapping is important for determining surgical candidacy and also in epilepsy surgery planning. However, in young children and uncooperative patients, language mapping has been particularly challenging despite the advances in performing noninvasive functional studies. In this study the authors review a series of children with epilepsy who underwent language mapping with magnetoencephalography (MEG) while sedated or sleeping, to determine receptive language localization for presurgical evaluation. METHODS The authors undertook a retrospective review of patients who underwent MEG between December 2007 and July 2009, and identified 15 individuals who underwent passive language testing as part of their presurgical evaluation because they were unable to participate in traditional language testing, such as Wada or functional MRI. Factors necessitating passive language testing included age and neurocognitive development. RESULTS Three of the 15 patients were deemed candidates for epilepsy surgery based on the results from standard preoperative testing, including video electroencephalography, MRI, and passive receptive language testing using MEG technology. The MEG studies were used successfully to localize language in all 3 patients, creating opportunities for seizure freedom through surgery that would not otherwise have been available. All 3 patients then underwent resective epilepsy surgery without experiencing postoperative language deficits. CONCLUSIONS This case series is the first to look at language mapping during sleep (passive language mapping) in which MEG was used and is the first to evaluate passive language testing in a patient population with intracranial pathological entities. This case series demonstrates that MEG can provide an alternative method for receptive language localization in patients with barriers to more traditional language testing, and in these 3 cases surgery was performed safely based on the results.

Microencephaloceles: another dual pathology of intractable temporal lobe epilepsy in childhood

Temporal lobe encephaloceles can be associated with temporal lobe epilepsy. The authors report on the case of an adolescent with multiple microencephaloceles, in the anterolateral middle fossa floor, identified at surgery (temporal lobectomy) for intractable partial-onset seizures of temporal origin. Magnetic resonance imaging revealed only hippocampal atrophy. Subdural electrodes demonstrated ictal activity arising primarily from the anterior and lateral temporal lobe, close to the microencephaloceles, spreading to the anterior and posterior mesial structures. Pathological examination revealed diffuse temporal gliosis involving the hippocampus, together with microdysgenesis of the amygdala. The literature on epilepsy secondary to encephaloceles is reviewed and the contribution of the microencephaloceles to the seizure disorder in this patient is discussed.

Bilateral occipital dysplasia, seizure identification, and ablation: a novel surgical technique

MRI-guided thermal ablation is a relatively new technique utilising heat to ablate both tumours and epileptogenic lesions. Its use against epilepsy offers some patients a new and relatively safe way of reducing or aborting seizures. Most cases of MRI-guided thermal ablation have been performed in patients with isolated lesions. Placement of depth electrodes prior to laser ablation has been rarely performed. We present a case with bilateral independent lesions traversing eloquent cortex, which, after sampling for seizures and successful ablation, retained normal function. The patient is, to date, seizure-free.