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Objective To assess factors associated with favorable outcome in refractory insular epilepsy treated by volume‐based stereotactic radiofrequency thermocoagulation (RFTC). Methods We performed volume‐based RFTC in 19 patients (11 males, 7‐44 years old). The volume for thermocoagulation was identified by multimodal data including electroencephalography (EEG)‐video, magnetic resonance imaging (MRI), and fluorodeoxyglucose–positron emission tomography (PET) in all patients, and epileptogenic zone (EZ) was assessed by stereo‐electroencephalography (SEEG) in 16. MRI showed insular lesions in four patients (benign tumors, n = 2; focal cortical dysplasia [FCD], n = 1; polymicrogyria, n = 1). MRI was negative in 15 cases; however, PET was positive in 18, and FCD pattern was detected by SEEG in nine cases. The dominant hemisphere was involved in 12 cases. RFTC was performed as a separate procedure after SEEG, or as a single MRI‐guided procedure. The insular volume to be coagulated was determined by a tridimensional identification of the epileptogenic cortex using MRI, PET, and SEEG, and was destroyed with coalescent thermal lesions. Results Seizure‐free outcome was achieved in 10 patients (53%), including Engel class IA in three (follow‐up = 1‐12 years, mean = 5.4). The responder rate (including Engel classes I‐III) was 89%. Transient postoperative deficits (mild hemiparesia, dysarthria, hypoesthesia, dysgeusia) were observed in eight patients (42%), with rapid and total recovery in all but one with persistent mild dysarthria. Neurological deficits were related to higher number of RFTC procedures (P = .036) and greater volume of RFTC (P = .028). Neuropsychological status was unchanged or improved in all; however, psychiatric status transitorily worsened in three patients. Factors contributing to seizure‐free outcome were the detection of FCD pattern (P = .009), localized EZ (P = .038), low RFTC volume (P = .002), low number of RFTC procedures (P = .001), and low RFTC volume/number ratio (P = .012). Optimal volume of RFTC around 2 cm3 offered the best compromise between efficacy and safety. Significance RFTC may be curative in insular epilepsy after accurate localization of EZ with SEEG. Best outcome was associated with low volume of thermolesions.

Summary:Purpose: To evaluate the accuracy, feasibility and clinical value of both ictal and interictal y9"Tc-ethyl cysteinate dimer (ECD) single photon emission computed tomography (SPECT) in patients with medically refractory epilepsy.Methods: The study included 75 consecutive patients, 48 with temporal lobe epilepsy (TLE group), and 27 with extratemporal epilepsy (ExT group). The accuracy of SPECT was analyzed considering the final diagnosis reached by convergence of clinical, electrophysiologic, structural, pathologic and outcome data.Resulw Ictal SPECT correctly identified the epileptogenic zone in 21 (91.3%) of 23 patients, whereas interictal SPECTs could correctly identify the epileptogenic zone in only 41(62.1%) of 66 patients (x' = 5.56, df = 1, p < 0.05). Results were similar when the two study groups were analyzed separately. Moreover, ictal studies had significantly higher specificity (91.3 vs. 60.6%) and positive predictive value (91.3 vs.66.2%) than interictal studies for the whole series of patients. Considering all tools used in the preoperative workup of these patients, ictal SPECT significantly contributed to the final topographic diagnosis in seven of 14 patients from TLE group and in six of nine patients from the ExT group. In these patients, ictal SPECT either obviated the need for invasive EEG or helped to define where to concentrate the efforts of invasive investigation.Conclusions: These data demonstrate that ictal SPECT can be easily achieved by using 9' "' Tc-ECD and can accurately localize the epileptogenic zone in both temporal and extratemporal epilepsies. Ictal ECD SPECT proved to be significantly more sensitive and specific than interictal ECD SPECT, and clinically useful in the definition of the epileptogenic zone. Key Words: Epilepsy-Single photon emission computed tomography-Ethyl cysteinate dimer-Seizures-Epilepsy surgery.Functional neuroimaging techniques, including singlc photon emission computed tomography (SPECT), have an established role in the preoperative workup of patients with refractory epilepsy (1-3). Indeed, ictal SPECT with an already well-known agent, hexamethyl propyleneamine oxime (HMPAO), has proved to be one of the most sensitive techniques for the localization of ictal onset zones (4-8). Conversely, the interictal modality of SPECT, although easier to obtain, has lower sensitivity (ranging from 30 to 80%) and specificity (from 36 to 95%) for the localization of the epileptogenic zone (3, 9-1 5).

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