ENTORHINAL CORTEX INVOLVEMENT IN NEURAL NETWORKS UNDERLYING MESIAL AND MESIAL-LATERAL TEMPORAL LOBE SEIZURES
Abstract number :
3.045
Submission category :
Year :
2002
Submission ID :
98
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Fabrice Bartolomei, Fabrice Wendling, Daniela Andrade, Jean Regis, Patrick Chauvel. Service de Neurophysiologie Clinique, INSERM9926- Hopital de la Timone, Marseille, France; Laboratoire de Traitement du Signal et de lImage, Universite Rennes 1, Rennes, F
RATIONALE: Temporal lobe seizures are the most frequent type of partial seizures and they are often drug-resistant. The underlying mechanisms of seizure generation are unknown. An increasing number of experimental works have shown evidence for the involvement of the entorhinal cortex in TLE pathogenesis. However, the role of EC in TLEs genesis has been poorly directly documented in human TLEs.
This study is aimed at determining the respective role of the EC and other temporal lobe structures in the genesis of TLE seizures recorded by depth electrodes (stereoelectroencephalography, SEEG) in patients undergoing presurgical evaluation.
METHODS: 24 seizures from 13 patients with TLEs affecting the medial structures were analyzed.
In addition to visual analysis of SEEG recordings and according to our previous studies, a nonlinear measure (nonlinear correlation) of signal interdependencies was used to evaluate the degree and direction of functional couplings occurring between temporal lobe regions during seizures.
RESULTS: Three patterns of seizure onset were defined: i/Pattern 1in which a fast low-voltage discharge is preceded by a complex of slow waves, ii/Pattern 2 characterized by the occurrence of a periodic discharge of high voltage spikes with a frequency [lt] 2hz iii/Pattern 3 in which no prior change is observed before the emergence of the ictal discharge in the temporal structures. During the seizure initiation, the EC was the leader structures in seizures with pattern 3 and in patients with lesions affecting this region (pattern 1). In contrast, amygdala and hippocampus were the most important structures eliciting ictal activity in pattern 2 seizures.
CONCLUSIONS: The temporal lobe seizures can not be restricted to a single anatomo-physiological scheme but involve various types of interactions between the neural structures. The entorhinal cortex is involved in seizure generation in various ways. It appears to be the key structure in seizures starting with a rapid discharges arising from the medial structures
[Supported by: INSERM]