Can epileptologists without access to intracranial EEG use reliably the International League Against Epilepsy classification of the localization-related epileptic syndromes? A stereo-electroencephalographic study.

The goal of the present study was to investigate the reliability of clinical and electroencephalographic (EEG) criteria for the classification of localization-related epileptic syndromes as listed in the Proposals of Revised Classification of Epilepsies and Epileptic Syndromes 1989 (ICE). ICE distinguishes between multiple syndromes within epilepsies of a given lobe. Intracranial recordings were the main element in the development of the revised ICE. Considering that most epilepsy centers have no access to such invasive techniques for precise anatomic localization, it was of interest to assess how accurately the seizure origin could be determined from the scalp EEG and clinical data as reported in ICE. In this retrospective study, we compared the accuracy of the topographic diagnosis made by two groups of physicians evaluating the same patients-one group with and the other without access to results of stereo-EEG (SEEG). Medical files of 87 patients with intractable localization-related epilepsy were analyzed: 38 with frontal, 37 with temporal, 10 with parietal, and 2 with occipital lobe epilepsy were included in the study. All patients underwent previous SEEG and successful cortectomy. Minimum follow-up was 5 years. In most cases, noninvasive techniques and criteria suggested by ICE allowed topographic diagnosis of focal epilepsies according to brain lobe involvement. More detailed diagnosis, localizing the origin of critical activity within a lobe, was often unreliable. Further data are required for a definition of the epileptogenic zone. A spatiotemporal evaluation of critical events, including the intracranial EEG recording, remains the best method for topographic diagnosis of localization-related epilepsy.

Anatomical origin of déjà vu and vivid 'memories' in human temporal lobe epilepsy.

Jackson (Brain 1898; 21: 580-90) observed that seizures arising in the medial temporal lobe may result in a 'dreamy state', consisting of vivid memory-like hallucinations, and/or the sense of having previously lived through exactly the same situation (déjà vu). Penfield demonstrated that the dreamy state can sometimes be evoked by electrical stimulation of the lateral temporal neocortex, especially the superior temporal gyrus. Halgren et al. (Brain 1978; 101: 83-117) showed that the dreamy state can be evoked by stimulation of the hippocampal formation and amygdala and Gloor (Brain 1990; 113: 1673-94) has suggested that it is evoked by lateral stimulation only when the resulting after-discharge spreads medially. In order to resolve the relative importance of these areas, we considered the mental phenomena observed in epileptic patients with electrodes stereotaxically implanted into different brain areas for seizure localization prior to surgical treatment. Sixteen patients, all with seizures involving the temporal lobe, experienced the dreamy state either as a result of spontaneous seizures (nine dreamy states in six patients), or due to electrical stimulation (43 in 14) or to chemical activation (five in three). Déjà vu and hallucinations of scenes were often evoked by different stimulations of the same electrode in the same patient. As Jackson had also observed, the dreamy state could occur alone but was often associated with epigastric phenomena and fear, and followed by loss of contact and oro-alimentary automatisms, and then by simple gestural automatisms, all characteristic of partial seizures beginning in the medial temporal lobe. Furthermore, as also emphasized by Jackson, the dreamy state was seldom associated with sensory illusions. Stimulation of either the neocortex (15 occurrences), anterior hippocampus (17) or amygdala (10) could evoke a dreamy state. However, since fewer hippocampal and amygdala leads were stimulated than temporal neocortical, the proportion of medial temporal electrodes where dreamy states could be evoked was much higher than in the neocortex. Most responsive lateral temporal sites were located in the superior temporal gyrus, rather than the middle temporal gyrus which was significantly less responsive. In 85% of dreamy states evoked by medial temporal lobe stimulation, the discharge spread to the temporal neocortex; and in 53% of dreamy states evoked by lateral temporal stimulation, the discharge spread medially. Considering all dreamy states, the amygdala was involved (as the stimulated structure, or as the site of ictal- or after-discharge) in 73% of cases, the anterior hippocampus in 83% and the temporal neocortex in 88%.(ABSTRACT TRUNCATED AT 400 WORDS)

Pathological left-handedness. Left-handedness correlatives in adult epileptics.

Factors associated with left-handedness were examined in a large sample of adults who suffered with epileptic seizures (n = 446) in an attempt to delineate the concept of pathological left-handedness. Three main pathological factors were found associated with left-handedness: (i) right-hemiparesis of early onset; (ii) cognitive deficit; (iii) evidence of left-hemisphere disease on clinical examination. Familial sinistrality was also associated with left-handedness, independently of the above-mentioned pathological factors. Results support a clear-cut distinction between normal and pathological left-handedness. This distinction seems presently important for the evaluation of the great number of anomalies proposed to be associated with left-handedness.

Surgical therapy for frontal epilepsies.

We have described our 25 years experience concerning 100 patients operated on for frontal epilepsy. Results show that 55% of patients are practically cured of their seizures and that 76% benefited from cortectomy (reduction of more than 75% of seizures). These results are the worst in the total series of St. Anne. Reasons for success and especially failure were analyzed in detail: 1. SEEG methods gave good indications along three dimensions of the limits and borders of the cortical excision. 2. When clinical semiology and organization of ictal discharges give evidence for rapid bilateral discharge, with involvement of axial musculature and generalized tonic-clonic manifestations, experience shows that it is necessary to combine cortectomy with a section of the adjacent cortico-subcortical fibers of the corona radiata, as if propagation of ictal discharges were impeded if not interrupted by sectioning such fibers and the primary site were incapable of expressing itself clinically. 3. If the characteristics of seizures suggest the quasisimultaneous involvement of the two frontal lobes and the existence of bilateral multifocal epilepsy, we suggest that a systematized anterior callosotomy might lead to useful results. 4. Finally, we propose general criteria for indications and contraindications for surgery.

Evidence for a contribution of the auditory cortex to audiospinal facilitation in man.

Facilitation of the spinal monosynaptic reflex by auditory stimulation has been demonstrated previously in animals and man. Analysis of the time course of audiospinal facilitation (ASF) in normal subjects is reported. The role of the cerebral cortex in the control of audiospinal facilitation was investigated in 32 patients with anatomically well-circumscribed lesions, the precise topography of which was determined stereotaxically. Lesions of the caudal part (Heschl's gyrus and temporal plane) of the superior temporal gyrus selectively depressed ASF evoked by contralateral auditory stimulation. In contrast, lesions in temporal, parietal and occipital lobes had no effect. Results obtained with frontal lobe lesions were not homogeneous. The specific involvement of auditory cortex in the gating of behavioral audiomotor reactions is discussed.

[Early right posterior cerebral hemispheric lesion and right speech dominance in 2 right-handed female patients]. / Lésion hémisphérique cérébrale postérieure droite précoce et dominance droite pour le langage chez deux droitières.

Two female patients presented a severe partial epilepsy of early onset and an extended right posterior hemispheric lesion of prenatal or perinatal origin. They were right-handed and all their first degree relatives were right-handed. Nevertheless, evidence of right hemispheric speech was documented in both patients, on the basis of a bilateral sodium amytal test in one case, and of a persistent aphasia after neurosurgical treatment in the other. The possible consequences of an early cerebral pathology on cerebral lateralization are discussed, including pathological right-handedness.

Stereotactic investigations in frontal lobe epilepsies.

The aim of a Stereo-EEG investigation is to verify and prove that the hypothesis, done on the basis of the preliminary investigations (clinical, EEG, neuroradiological), are correct. This task is particularly hard in frontal lobe epilepsies, because of anatomical and physiopathological reasons. Among 277 consecutive patients, 86 were explored for a probable frontal epilepsy. The stereotactically introduced electrodes. 1) simultaneously record the electrical activity on both, mesial and lateral cortical areas, and, 2) in 3/4 of cases also investigate extra-frontal, mainly temporal, areas. Two small, non-surgical haematomas were provoked in one patient. The spatial trajectory of the discharges, evaluated with this methodology, permits of limiting the surgical removal in many cases.

Hemispheric lateralization of motor and speech functions after early brain lesion: study of 73 epileptic patients with intracarotid amytal test.

This study reports results of a bilateral intracarotid amytal test in 73 epileptic patients with medically intractable focal seizures. No right-handers but 50% of left-handers have a right dominance for speech in this particular population. Lateralization of cerebral speech functions, as well as manual preference, are dependent on the neurological disease and can shift conjointly or independently. We study the relationships of those shifts to different variables related to the cerebral pathology: age at onset and lateralization of epilepsy, extensive brain damage, neurological deficit.