Robert Kuba

Ictal and peri-ictal oscillations in the human basal ganglia in temporal lobe epilepsy

Preictal, ictal, and postictal oscillations in the basal ganglia were analyzed. Five persons with temporal lobe epilepsy who were candidates for surgery had diagonal depth electrodes implanted in the basal ganglia: four of them in the putamen, and one in the pallidum and caudate. Time-frequency and power spectral analyses were used to analyze the EEG. Significant frequency components of 2-10 Hz were consistently observed in the basal ganglia. The frequency of this component slowed during seizures. There was a significant ictal increase in power spectral density in all frequency ranges. The changes in the basal ganglia were consistent while seizure activity spread over the cortex, and partially persisted after the clinical seizure ended. They were inconsistent in the period after seizure onset. Seizures originating in the mesiotemporal structures can affect physiological rhythms in the basal ganglia. The basal ganglia did not generate epileptiform EEG activity. An inhibitory role for the basal ganglia during temporal lobe seizures is suggested.

Lateralized ictal immobility of the upper limb in patients with temporal lobe epilepsy

The primary aim of this study was to establish the incidence and the lateralizing value of ‘lateralized ictal immobility of the upper limb’ (LIL) in patients suffering from temporal lobe epilepsy (TLE), and to describe the connection between LIL and other clinical ictal signs.

16. fMRI and eeg studies of the role of basal ganglia in epilepsy

(1) In the fMRI study the impact of epilepsy on the functional brain connectivity (FC) of the BG in two large-scale networks, the default mode network (DMN) and somatomotor network (SMN), was studied in 10 healthy control subjects (HC) and 24 patients with epilepsy. In HC, the BG were functionally negatively correlated with typical DMN regions. This negative correlation as well as the FC between the BG and SMN was significantly lower in patients ( Rektor et al., 2013 ). (2) SEEG studies: The human striatum and pallidum did not generate specific epileptic EEG activity, not even when the seizures were generalized. The visually observed slowing and amplitude increase in the BG was found with the spread of the epileptic activity from the hippocampus to other areas ( Rektor et al., 2002 ). Significant frequency components of 2–10xa0Hz, with the maximum in the 5–10xa0Hz range, were constantly observed in the BG ( Rektor et al., 2011 ). The frequency of this component slowed by around 2xa0Hz during seizures. There was a significant ictal increase of power spectral density in all frequency ranges. The changes in the BG were consistent while the seizure activity spread over the cortex, and they partially persisted after the clinical seizure ended. They were inconsistently present in the first period after the seizure onset. Conclusion Unlike in HC, in TLE the BG are not correlated with a DMN component, and the FC of the BG is decreased with SMN. The epileptic process reduces the FC between the BG and large-scale brain networks. This may reflect an altered function of the BG in epilepsy. Based on our SEEG studies, the time course of the oscillatory activities together with the absence of the epileptiform EEG activities in the BG lead us to suggest an inhibitory role of the BG in temporal lobe seizures. This “filtering effect” of the BG may act as an obstacle to the spread of ictal activity. The BG should be seriously considered as a potential target for neuromodulatory and pharmacological treatment of TLE.

P807: Basal ganglia in temporal lobe epilepsy – SEEG and fMRI studies

fusion on PASL-MRI that were adjacent to their lesions. Six patients showed normal findings or hypoperfusion on inter-ictal PASL-MRI in areas where CBF increased during peri-ictal states. Three patients showed epileptic abnormalities on EEG in regions that were almost concordant with areas showing hyperperfusion on PASL-MRI. Although 5 patients showed hyperintense areas on DWI, the remaining 5 patients failed to show hyperintense areas where PASL-MRI showed hyperperfusions. Conclusion: Although this study included a small sample size, PASL-MRI revealed significant changes in inter-ictal or peri-ictal states in patients with LRE and lesions. Thus, PASL-MRI is useful for identifying an epileptic focus.

S13-2 Basal ganglia (BG) recording in epilepsy

Objective: The preictal, ictal and postictal oscillations in the BG (BG) were analyzed. The human BG did not generate specific epileptic EEG activity, neither interictal nor ictal (Rektor et al., 2002). Methods: Five epilepsy surgery candidates with temporal lobe epilepsy had depth electrodes implanted in the amygdalo-hippocampal complex (AH), temporal, cingulate, prefrontal and orbitofrontal cortices. All patients had diagonal electrodes targeted in hippocampus with contacts in BG, four patients in putamen and one in pallidum and caudate. The time frequency analysis, the power spectral analysis, the spectral coherence and correlation in time domain were used for analysis of EEG. Results: 1. Significant frequency components of 2 10 Hz were constantly observed in BG. In the other structures it appeared less constantly than in BG. The frequency of this component was reduced during seizures in BG. 2. There was a significant increase of power spectral density across all structures in all frequency ranges during epileptic seizures. Number of seizures with significant spectral power increase was highest in BG. 3. In the pre-ictal period, the coherency between oscillations in the putamen and AH, the cingulate and the pallidum/caudate were significant. Significant coupling between oscillations in the BG activity and in the AH were displayed during seizures. The relationship between the epileptic activity in BG and other studied structures was less significant. 4. The changes in the BG were consistent while the seizure activity spread over the cortex and partially persisted after the clinical seizure ended. They were inconsistent in the first period after the seizure onset. Conclusion: The BG most likely cannot generate seizures but the BG circuits might influence the cortical epileptic activity, via their feed-back pathways to the cortex. An inhibitory role of BG during temporal lobe seizures is suggested. Supported by Research Project MSM0021622404