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Published on: January 6, 2011
Intra-operative cortical motor mapping using subdural grid electrodes in children undergoing epilepsy surgery
Puneet Jain1, Robyn Whitney1, Samuel Strantzas2
1Epilepsy Program, Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada.
Insights
Intra-operative direct cortical stimulation using subdural grids safely mapped motor function in children with epilepsy. This method may enhance extra-operative motor mapping during epilepsy surgery evaluation.
Area of Science:
- Neurosurgery
- Epileptology
- Neurophysiology
Background:
- Drug-refractory epilepsy requires precise surgical planning.
- Motor mapping is crucial for minimizing neurological deficits during epilepsy surgery.
Purpose of the Study:
- To review the use of intra-operative direct cortical stimulation using subdural grids (IODCS-SDG) for motor mapping in pediatric epilepsy surgery.
- To evaluate the safety and efficacy of IODCS-SDG compared to extra-operative direct cortical stimulation (EODCS-SDG).
Main Methods:
- Retrospective review of 20 children (<18 years) with drug-refractory epilepsy undergoing invasive EEG monitoring.
- Intra-operative motor mapping using subdural grid electrodes (IODCS-SDG) with train-of-five stimulation and motor-evoked potentials (MEPs).
- Comparison with intra-operative direct cortical stimulation via probe (IODCS-probe) and extra-operative direct cortical stimulation (EODCS-SDG).
Main Results:
- IODCS-SDG was safely completed in all 20 patients, with MEPs commonly recorded in deltoid, extensor digitorum communis, and first dorsal interosseus muscles.
- Median stimulation thresholds ranged from 40-60 µV.
- EODCS-SDG was less reliable, with incomplete mapping in 4/17 patients and higher rates of stimulation-provoked seizures (35.3%) and after-discharges (41.2%).
- 100% concordance between IODCS-SDG and EODCS-SDG was observed in common mapped regions for 9 patients.
Conclusions:
- Intra-operative direct cortical stimulation using subdural grids is a safe and feasible method for motor mapping in children with drug-refractory epilepsy.
- IODCS-SDG can be a valuable adjunct to EODCS-SDG, potentially improving the accuracy and reliability of motor mapping in pediatric epilepsy surgery evaluation.
Objectives:
The objective of this study was to review our experience with intra-operative "train of five" stimulation using subdural grid for motor mapping in children undergoing epilepsy surgery evaluation.
Methods:
Twenty consecutive children below 18-years of age with drug-refractory epilepsy who underwent invasive-EEG monitoring using subdural-grid placement and intra-operative motor mapping using direct cortical stimulation by sub-dural grid electrodes (IODCS-SDG) at our institution between January-2016 and June-2017 were reviewed. Stimulation was delivered through the subdural-grid electrodes using a train-of-five pulses and muscle responses were recorded by motor-evoked-potentials (MEPs). Intra-operative direct cortical stimulation delivered through a ball-tipped probe (IODCS-probe) and extra-operative motor-mapping (EODCS-SDG) were also performed.
Results:
IODCS-SDG was completed in 20 patients and subsequent EODCS-SDG was done in 17/20 patients. MEP responses were more commonly obtained in the deltoid (19/20), extensor-digitorum-communis (20/20) and first-dorsal-interosseus (19/20). The median thresholds varied between 40 V and 60 V for the six muscle groups. The respective IODCS-probe thresholds tended to be similar. No stimulation-provoked seizures or anaesthesia-related complications were noted during IODCS-SDG. EODCS-SDG could not be completed in 4/17 children and mapping data obtained was frequently inadequate. Nine patients demonstrated 100% concordance between IODCS-SDG and EODCS-SDG for the common mapped body regions. Stimulation-provoked seizures during EODCS-SDG were seen in 6/17 (35.3%) and after-discharges in 7/17 (41.2%) children.
Conclusions:
IODCS-SDG could be performed safely in children with drug refractory epilepsy undergoing invasive EEG monitoring.
Significance:
IODCS-SDG may be a useful adjunct to EODCS-SDG in motor mapping for children.
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