Intra-operative cortical motor mapping using subdural grid electrodes in children undergoing epilepsy surgery evaluation and comparison with the conventional extra-operative motor mapping

Clin Neurophysiol. 2018 Dec;129(12):2642-2649. doi: 10.1016/j.clinph.2018.07.022. Epub 2018 Aug 12.

Abstract

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.

Keywords: Cortical mapping; Electrocorticography; Epilepsy surgery; Invasive EEG monitoring; Refractory epilepsy.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • Electrodes / adverse effects
  • Electroencephalography / instrumentation
  • Electroencephalography / methods*
  • Epilepsy / surgery*
  • Female
  • Humans
  • Intraoperative Neurophysiological Monitoring / instrumentation
  • Intraoperative Neurophysiological Monitoring / methods*
  • Male
  • Motor Cortex / physiopathology
  • Motor Cortex / surgery*
  • Subdural Space / surgery*
  • Transcranial Direct Current Stimulation / instrumentation
  • Transcranial Direct Current Stimulation / methods