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Summary: Purpose: Several animal studies suggest that the thalamus might be involved in the maintenance and propagation of epileptic seizures. However, electrophysiologic evidence for this implication in human partial epileptic seizures is still lacking. Considering the rich and reciprocal connectivity of the medial pulvinar (PuM) with the temporal lobe, we evaluated a potential participation of this thalamic nucleus in temporal lobe epilepsy (TLE). Methods: The electrophysiologic activity of PuM was recorded during stereoelectroencephalographic exploration of spontaneous temporal lobe seizures in 14 patients referred for presurgical assessment of refractory TLE. Results: We recorded PuM ictal activity in 80% of the 74 seizures that we analyzed. This activity was characterized by rhythmic slow-waves or rhythmic spikes (RSW-RS) or both or by low-voltage fast activity (LVFA) in 64% and 36% of seizures, respectively. RSW-RS occurred mostly in seizures arising from mesiotemporal structures, whereas LVFA was more frequently observed in seizures of neocortical origin. In the 15 seizures without PuM ictal activity, spreading of the seizure outside the onset zone never occurred, whereas it did in 78% of seizures with PuM ictal involvement. Discharge propagation was systematic when PuM involvement corresponded to LVFA, whatever the seizure onset zone was, whereas it represented only 66% of the seizures when PuM exhibited RSW-RS. Conclusions: This study shows that ictal changes in PuM activity are frequently observed during temporal lobe seizures and suggests that this thalamic nucleus might participate in their propagation.

Summary: Purpose: The lateralizing value of ictal head deviation (HD) in frontal lobe epilepsy (FLE) is a matter of debate. Although FLE is typically associated with tonic or clonic HD contralateral to seizure onset, ipsilateral HD has been noted in numerous reports. Whether both types of HD can be distinguished according to their clinical patterns has not yet been specifically investigated. Methods: We studied the clinical pattern and time of occurrence of HD of 129 seizures in 13 consecutive patients, who underwent successful surgery for FLE, including 12 investigated with an intracerebral stereotactic EEG procedure. Results: Ictal HD was ipsilateral to the epileptogenic zone (EZ) in four (30%) patients and 27 (20.9%) seizures and contralateral in five (38%) patients and 15 (11.6%) seizures. Ipsilateral HD was rarely tonic and never associated with clonic manifestation. Contralateral HD was always tonic, unnatural, and associated with hemifacial clonic movements in 86% of seizures. Ipsilateral HD occurred earlier than contralateral HD (p < 0.03), with a mean delay of 1 ± 2s after the first detectable ictal sign, as compared with a delay of 17 ± 11 s for contralateral HD. Moreover, ipsilateral HD always occurred before contralateral HD when both signs coexisted in the same seizure. Our patients with ipsilateral HD demonstrated either an anterior or dorsolateral frontal EZ. Conclusions: Ipsilateral HD is a common ictal sign during FLE and can be distinguished from contralateral HD by its time of occurrence at or immediately after seizure onset and its lacking association with clonic movements. Ke yW ords: Version— Head deviation—Frontal lobe epilepsy.

Summary: Purpose: Depth electrodes recordings may be required in some cases of epilepsy surgery to delineate the best region for cortical resection. We usually implant depth electrodes according to Talairach’s stereoelectroencephalography (SEEG) method. By using these permanently implanted depth electrodes, we are able to perform radiofrequency (RF)-thermolesions of the epileptic foci. We report the technical data required to perform such multiple cortical thermolesions, as well as preliminary results in terms of seizure outcome in a group of 20 patients. Methods: Lesions were performed by using 100- to 110-mA bipolar current (50 V), applied for 10 to 50 s. Each thermocoagulation produced a 5- to 7-mm diameter cortical lesion. In total, two to 16 lesions were performed in each of the 20 patients. Lesions were placed without anesthesia. No general or neurologic complication occurred during the procedures. Two transient postprocedure side effects, consisting of paresthetic sensations in the mouth and mild apraxia of the hand, were observed. Results: At a follow-up time of 8 to 31 months (mean, 19 months), 15% of the patients became seizure free, 40% experienced a ≥80% reduction of their seizure frequency, and 45% were not significantly improved. Conclusions: SEEG-guided RF thermolesions is a safe technique. Our preliminary results indicate that such lesions can lead to a significant reduction of seizure frequency and could be proposed as a palliative procedure if no resective surgery is possible. A randomized controlled trial is needed to determine which patients are likely to respond to SEEG-guided RF ther

Summary: Purpose: We report the results of 75 intracortical electrical stimulations of the insular cortex performed in 14 patients during stereo-electroencephalography (SEEG) investigation of drug-resistant partial epilepsy. The insular cortex was investigated on electroclinical arguments suggesting the possibility of a perisylvian spread or a rapid multilobar diffusion of the discharges during video EEG. Methods: In these 14 patients, 27 stereotactically implanted transopercular electrodes reached the insular cortex (11 the right insula, 16 the left insula). Square pulses of current were applied between the two deepest adjacent contacts of each transopercular electrode using low (1 Hz) or high-frequency (50 Hz) stimulation. Only symptoms evoked in the absence of afterdischarges were analyzed. Results: Clinical responses were evoked in 10 of the 14 patients (in 20 of the 27 insular sites) and showed a clear topographic specificity inside the insular cortex. Viscerosensitive and visceromotor responses, similar to those evoked by temporomesial stimulation, were evoked by anterior insular stimulation and somesthetic sensation, similar to those evoked by opercular cortex stimulation, by posterior insular stimulation. Conclusions: The topographic organization of the induced responses within the insular cortex suggest that two different cortical networks, a visceral network extending to the temporomesial structures and a somesthetic network reaching the opercular cortex, are disturbed with stimulation of the anterior or the posterior insula, respectively. Thus ictal symptoms associated with the spread of the epileptic discharges to the insular cortex might be difficult to distinguish from those usually reported during temporomesial or opercular discharges.

Summary: Purpose: This study explored the mechanism of light-induced complex partial seizures by using ictal intracerebral recordings in a patient with refractory epilepsy of the right temporal lobe. Methods: Presurgical evaluation of this patient was realized by means of video-EEG recordings, WADA test, magnetic resonance imaging (MRI), F”-deoxyglucose and C’ Iflumazenil positron emission tomography (PET) interictal neuroimaging data, and stereoelectroencephalographic (SEEG) ictal recordings. Results: SEEG investigations demonstrated the right mesiotemporal origin of all the patient’s seizures. This result was confirmed by a successful right temporal lobectomy. Moreover, SEEG recordings revealed a frequent interictal spiking activity in the right occipital visual cortex that was undetectable on scalp recordings. However, the occipital cortex was not involved at the onset of mesiotemporal ictal discharges and was not hyperresponsive to focal electrical stimulation. Conclusions: This study shows that, in spite of interictal occipital spiking, the photosensitivity of mesiotemporal seizures can be observed in both the absence of occipital cortex involvement during ictal discharges and demonstrable hyperexcitability of the occipital cortex to light or direct electrical stimulation. Key Words: Light-induced seizures-Temporal lobe epilepsy-SEEG-Epilepsy surgery.

Summary: Single-photon emission computed tomography (SPECT) and [99mTc]HMPAO were used to assess the functional significance of nonspecific magnetic resonance imaging (MRI) abnormalities observed in patients with temporal lobe epilepsy and no focal lesion on CT scan. We studied 18 patients whose MRI was normal or showed high signal intensity on T2-weighted images (T2WIs) at the site of the EEG focus in 11 and 7 cases, respectively. EEG was monitored during regional cerebral blood flow (rCBF) study. Lateralized hypoperfusion was present in 7 of 17 interictal(41%) and in one Postictal cases; it was located in the temporal lobe on the side of the EEG focus in all, and was significantly more frequent in patients with high signal intensity on T2WI (86%) than in patients with a normal MRI (18%). The degree of temporal perfusion asymmetry measured in each individual was higher in patients whose MRI was abnormal. RESUME Le SPECT AU Tc 99m-HMPAO a ete utilise pour evaluer la signification fonctionnelle d'anomalies non specifiques a I'IRM retrouvees chez des patients presentant une epilepsie du lobe temporal en l'absence de lesions focales a la scanographie. Les auteurs ont etudie 18 patients presentant une IRM normale ou presentant des images de haute intensite en T2 pondere au niveau du site du foyer epileptique (I 1 et 7 cas respectivement). L'EEG a ete enregistre pendant I'etude du flux sanguin cerebral regional. Une hypoperfusion lateralisee etait presente en etat intercritique 7 fois sur 17, et dans un cas evaluee en postcritique. Elle etait localisee au niveau du lobe temporal du cote du foyer EEG dans tous les cas, elle etait significativement plus frequente chez les patients presentant un signal de haute intensite en T2 pondere (86%) que chez les patients presentant une IRM normale (18%). Le degre d'asymetrie de perfusion temporale mesure chez chaque patient etait plus eleve chez les patients avec IRM anormale. RESUMEN Para determinar el significado funcional de las anormalidades inespecificas que aparecen en la Resonancia Magnetica (MRI) de pacientes con epilepsia de 1obulo temporal y sin lesiones focales en la Tomografia Computarizada, se han utilizado la Tomografia Computarizada por Emision de Fotonsimple (SPCT) y TC 99M-HMPAO. Hemos estudiado 18 pacientes en los que la MR fue normal o mostro senales de aka intensidad en las imagenes T2 (T2WI) en el lugar del foco del EEG en 11 y 7 casos respectivamente. El EEG fue monitarizado durante estudios de flujo cerebral regional (rCBF). Se encontro una hipoperfusion lateralizada en 7 de 17 casos interictales (41%) y en 1 postictal que se localizo en el 1obulo temporal del lado del foco del EEG en todos los casos y fue significativamente mas frecuente en pacientes con alta senal de intensidad en TZWI (86%) que en pacientes con una MRI normal (18%). El grado de asimetria de la perfusion temporal fue medido en cada individuo y fue mayor en 10s pacientes en 10s que la MRI fue anormal. ZUSAMMENFASSUNG Single-Photon-Emissions-Computertomographie (SPECT) und Tc99m-HMPAO wurden zur Untersuchung der funktionellen Signifikanz nicht spezifischer magnetresonanztomographischer Abnormitaten benutzt, die bei Patienten mit Temporallappenepilepsie und fehlenden fokalen Lasionen im CT gesehen wurden. Wir untersuchten 18 Patienten, deren MRT normal war (11) oder eine hohe Signalintensitat in der T2-Gewichtung auf der Seite des EEG-Fokus (7 Falle) zeigte. Das EEG wurde wahrend der regionalen zerebralen Blutfluβuntersuchung (rCBF) abgeleitet. Eine lateralisierte Hypoperfusion trat bei 7 von 17 Pattienten (41%) interiktal auf, bei einem Patient postiktal; sie war bei allen Fallen im Temporallappen auf der Seite des EEG-Fokus lokalisiert und war bei Patienten mit hoher Signalintensitat im T2-Bild signifikant haufiger (86%) als bei Patienten mit normalem MRT (18%). Das Ausmaβ der temporalen Perfusionsasymmetrie war hoher bei Patienten mit abnormem MRT.