Abstracts

As opposed to seizures of temporal, frontal or occipital origin, the semiology of parietal seizures (PS) is not well known. This is partly due to their rarity since they represent less than 5% of partial seizures reported in surgical series. We believe that PS are actually underestimated because a number of them is unrecognized : if the ictal symptomatology is dominated by somato sensitive or painful symptoms, these presence is not nevertheless compulsory . Our study illustrates this fact by reporting two patients cases followed for frontal lobe epilepsy (FLE) and whom seizures originate from parietal lobe Ten to fifteen patients suffering from FLE benefit annually in our pre surgical unit evaluation from SEEG exploration. During last year, we were forced to repeat the exploration of two of them because the frontal lobe exploration was unable to localize the epileptogenic zone (EZ) but indicated the retro rolandic origin of seizures. The second exploration in these two patients was focused on the parietal lobe Seizures in the first patient began with a sudden assumption of a fixed posture of left upper arm abducted at the shoulder and with left head and eye deviation and speech arrest. In the second patient, seizures began suddenly with complex motor automatism taking a frenetic agitation aspect without loss of consciousness, often occurring in nocturnal cluster. No somato sensory sensations were reported by any of the two patients. The SEEG exploration showed the discharge development in a extended frontal network but did not allow the precise origin of seizures. These two patients benefited a second SEEG exploration centered on the post central areas and the parietal lobe. In the first case, seizures originated in the right supra marginal gyrus, propagating in the internal aspect of the parietal lobe to reach the homolateral supplementary motor area. In the second patient, seizures originated in the left angular gyrus and propagated in the external homolateral pre frontal cortex. Our study demonstrated that the PS could present in very different ways and in the absence of any somato sensitive symptomatology. The indentification difficulties could explain why parietal epilepsy cases are so rarely reported in litterature. These seizures could be of frontal type and in the absence of an adapted intracranial EEG exploration, explain some surgical failures in patients treated by inadequated corticectomy for unrecognized PLE