Relationship between Postoperative EEG Driving Response and Lead Location in Deep Brain Stimulation of the Anterior Nucleus of the Thalamus for Refractory Epilepsy.

ABSTRACT

OBJECTIVES: Interpreting the postoperative electroencephalographic (EEG) driving response (DR) as an indicator of electrode placement within the thalamic nucleus in deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) for refractory epilepsy is controversial. MATERIALS AND METHODS: We retrospectively investigated the relationship between postoperative EEG DR and the location of 11 electrodes in 6 patients who underwent ANT DBS for refractory epilepsy. RESULTS: Cerebral synchronizing EEG DR was observed in 10 electrodes. However, 9 of the 11 electrodes were located within the ANT. For the 2 electrodes that missed the ANT, DR was observed in 1 misplaced electrode facing the anterior surface of the ANT within the third ventricle. The other misplaced electrode without DR elicitation showed a DR after electrode repositioning. CONCLUSIONS: The diagnostic significance of DR as indirect evidence of electrodes being within thalamic nuclei is limited. If DR is not elicited, it should be regarded as a misplacement. Even if DR is elicited, it may not be interpreted as a sound indicator of proper electrode placement within the thalamus. A sophisticated, postoperative imaging study is warranted in every case of ANT DBS.