Corpus callosotomy in multistage epilepsy surgery in the pediatric population

Clinical article

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The object of this study was to evaluate surgical outcome in a select group of patients with medically refractory epilepsy who had undergone corpus callosotomy combined with bilateral subdural electroencephalography (EEG) electrode placement as the initial step in multistage epilepsy surgery.


A retrospective chart review of 18 children (ages 3.5–18 years) with medically refractory symptomatic generalized or localization-related epilepsy was undertaken. A corpus callosotomy with subdural bihemispheric EEG electrode placement was performed as the initial step in multistage epilepsy surgery. All of the patients had tonic and atonic seizures; 6 patients also experienced complex partial seizures. All of the patients had frequent generalized epileptiform discharges as well as multifocal independent epileptiform discharges on surface EEG monitoring. Most of the patients (94%) had either normal (44%) MR imaging studies of the brain or bihemispheric abnormalities (50%). One patient had a suspected unilateral lesion (prominent sylvian fissure).


Of the 18 patients who underwent corpus callosotomy and placement of subdural strips and grids, 12 progressed to further resection based on localizing data obtained during invasive EEG monitoring. The mean patient age was 10.9 years. The duration of invasive monitoring ranged from 3 to 14 days, and the follow-up ranged from 6 to 70 months (mean 35 months). Six (50%) of the 12 patients who had undergone resection had an excellent outcome (Engel Class I or II). There were no permanent neurological deficits or deaths.


The addition of invasive monitoring for patients undergoing corpus callosotomy for medically refractory epilepsy may lead to the localization of surgically amenable seizure foci, targeted resections, and improved seizure outcomes in a select group of patients typically believed to be candidates for palliative surgery alone.

Abbreviations used in this paper: EEG = electroencephalography; FSIQ = full-scale intelligence quotient; iEEG = intracranial EEG; SUDEP = sudden unexplained death in epilepsy; VABS = Vineland Adaptive Behavior Scales.

Article Information

Address correspondence to: Sean M. Lew, M.D., Department of Neurosurgery, Children's Hospital of Wisconsin, 999 North 92nd Street, Suite 310, Milwaukee, Wisconsin 53226. email:

© AANS, except where prohibited by US copyright law.



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    Case 13. Postoperative skull radiograph demonstrating C-shaped interhemispheric grid and bilateral subdural electrode placement following callosotomy.

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    Bar graph demonstrating seizure outcome in 18 patients undergoing callosotomy with concurrent bilateral intracranial monitoring. Twelve patients underwent further resection (gray bars), and 6 patients had callosotomy without further resection (black bars). Engel Class I, seizure free; II, rare disabling seizures; III, worthwhile seizure reduction; and IV, no worthwhile improvement in seizures.

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    Case 13. Preoperative MR imaging. Left: Sagittal T1-weighted MR image showing a markedly diminished posterior corpus callosum. Right: Coronal FLAIR sequence demonstrating diminished white matter volume with abnormal hyperintensity bilaterally.

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    Case 13. Coronal ictal FDG-PET images demonstrating increased uptake in the right hemisphere relative to the left, most prominently in the frontal and parietal lobes.

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    Case 13. Preoperative surface awake EEG traces showing independent, bilateral, generalized, multifocal discharges maximally seen in the right hemisphere.

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    Case 13. Preoperative surface asleep EEG traces showing generalized continuous spike and slow-wave discharges consistent with electrographic status epilepticus of slow-wave sleep.

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    Case 13. Tracings from iEEG following corpus callosotomy (2-sided interhemispheric grid and bilateral electrode strips). Right-sided electrodes are represented on the top half of the tracings, left-sided electrodes on the bottom half. Maximal epileptiform activity was seen in the right hemisphere, predominantly in the posterior quadrant.


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