Ictal limb dystonia in temporal lobe epilepsy. an invasive video-EEG finding

The aim of the investigation was to evaluate the ictal EEG in the putamen and the temporal and frontal lobes during contralateral ictal limb dystonia (ID). Ten epilepsy surgery candidates participated in the study. All of them were investigated using intracerebral and/or subdural electrodes. In four of the patients, the putamen was investigated with diagonal depth electrodes (patients 1-4), in six of the patients, both the temporal and frontal lobes were investigated (patients 5-10). All of the investigated contacts were located contralateral to the side of the ictal dystonia. All of the patients suffered from temporal lobe epilepsy (TLE); in patient 10, both temporal and frontal seizure types were recorded. A total of 20 complex partial seizures (CPS) were analysed. ID was never an early symptom in the course of CPS. Slow activity was recorded in the putamen in all 10 seizures of the four patients in whom the putamen was investigated (patients 1-4). In five of these seizures, there was a time-locked change in the ictal EEG in relation to the ID (slowing of activity in three seizures; acceleration in two seizures). At the time of the onset of ID, several cortical regions were involved in the ictal discharge, within both the contralateral temporal and frontal lobes. In all 10 seizures of the six patients in whom both the temporal and frontal lobes on the contralateral side were evaluated (patients 5-10), the ictal paroxysmal discharge was noted in both lobes (i.e. frontal and temporal) at the time of ID onset. We can conclude that ID is a late symptom in TLE. Widespread activation of the contralateral temporal and frontal lobes is needed for the appearance of ID; however, the critical region responsible for the genesis of ID was not revealed. Although there are some non-specific changes in the putamen contralateral to ID, the changes were never epileptic in type. The putamen probably collaborates in the genesis of ID, but it does not generate the epileptic discharge during its course.