Use of Subtemporal Electrode Chains and Their Contribution to Presurgical Evaluation

ABSTRACT

Subtemporal electrode chains are part of the international 10-10 system. Since 2012, they have been routinely used at our institution in adult patients with intractable epilepsy who are undergoing video EEG evaluation for epilepsy surgery. In 2016, this was extended to the pediatric population. However, there are few data regarding the utility of these electrodes. We performed a retrospective study to investigate the sensitivity and specificity for detection and lateralization of an ictal EEG pattern in patients with temporal lobe epilepsy. Neurophysiologists and EEG technologists were randomly shown samples containing interictal EEG or ictal patterns in standard biploar montage (anterior-posterior bipolar with international 10-20 electrodes only), modified bipolar montage with subtemporal chains, or modified bipolar montage with T1 and T2 electrodes added. Subtemporal chains improved sensitivity compared with standard bipolar, but they also reduced the specificity. T1 and T2 electrodes showed a nonsignificant trend towards improved sensitivity and specificity compared with standard bipolar. There was no difference in sensitivity for correct lateralization among the three montages.

KEY WORDS:

• 10-10 placement
• epilepsy surgery
• Phase II monitoring
• subtemporal chain
• temporal lobe abnormalities