[Surgical resections in functional areas: report of 89 cases]. / Résections en région fonctionnelle: étude d'une série de 89 cas.

Surgical resections for intractable epilepsy are generally associated with a high risk of permanent neurological deficit and a poor rate of seizure control. We present a series of 89 patients operated on from 1992 through 2007 for drug-resistant partial epilepsy, in whom surgery was performed in a functional area of the brain: the central (sensorimotor and supplementary motor areas) region in 48 cases, posterior regions (parietal and occipital) in 27, the insula in eight, and the language areas in six. Epilepsy was cryptogenic in 12 patients, and lesion-related in 77: malformation of cortical development in 43, tumor in 17, perinatal cicatrix in 13, vascular lesion in three, and another prenatal lesion in one. Seventy patients underwent stereoelectroencephalographic (SEEG) exploration. The surgical procedure was resective (lesionectomy or SEEG-guided corticectomy) in 83 patients and multiple stereotactic thermocoagulations in six. Ten patients were reoperated because of early seizure recurrence. A postoperative complication was observed in 12 patients. Postoperative deficits were observed in 54 patients (61%) and resolved completely in 29. In 25, a permanent deficit persisted, minor in 19 and moderate to severe in six, which did not correlate with localization or etiology. With a one-year follow-up in 74 patients (mean, 3.6 years), 53 (72%) were in Engel's class I, including 38 (51%) in class IA. Seizure outcome was significantly associated with etiology: 93% of Taylor-type focal cortical dysplasia, whereas only 40% of cryptogenic epilepsies were in class I (p<0.05). This suggests that resective or disconnective surgery for intractable partial epilepsy in functional areas of the brain may be followed by excellent results on seizures and a moderate risk of permanent neurological sequelae.

[Predictors of verbal memory decline following temporal lobe surgery]. / Facteurs de risque du déclin mnésique verbal après chirurgie du lobe temporal.

BACKGROUND AND PURPOSE: Verbal memory decline can occur after temporal lobe surgery, especially when the left dominant hemisphere is involved. This potential functional risk must be evaluated before surgery. Among all factors that have been identified by several studies, the side of surgery (left dominant) and high baseline memory performance have been found to be predictive of verbal memory decline. Other factors such as etiology, sex, age at surgery, age at seizure onset, and duration may influence memory decline, but the results are not clear. Our purpose was to identify, in our population of patients and among all risk factors, those that may be predictive of verbal memory decline. METHODS: Logistic regression was used to examine the effect of each factor on the postoperative verbal memory index (WMS-R) in 101 patients who underwent a right (n=49) or left (n=52) anterior temporal lobe resection. RESULTS: In the group as a whole, 22 % of the patients demonstrated verbal memory decline of more than one standard deviation. The verbal memory decline was significantly related to surgery on the left side and a high level of verbal memory performance. These factors were significant predictors of decline. The other factors (etiology, sex, age at surgery, age at seizure onset, and duration) were not found to be predictive of this decline. CONCLUSIONS: Our analysis demonstrates that the patients who are most at risk of undergoing verbal memory deterioration are those who undergo left-sided temporal resection and have good memory scores preoperatively. The contradictions found in the literature about the other factors could be explained by the diversity of the tests and criteria used to assess memory decline.

Functional MR imaging in assessment of language dominance in epileptic patients.

The value of functional MR Imaging (fMRI) in assessing language lateralization in epileptic patients candidate for surgical treatment is increasingly recognized. However few data are available for left-handed patients. Moreover determining factors for atypical dominance in patients investigated with contemporary imaging have not been reported. We studied 20 patients (14 males, 6 females; 9 right handed, 11 left handed) aged from 9 to 48 years, investigated for intractable partial epilepsy. Epileptic focus location was temporal in 14 cases, extratemporal in 6, and lateralized in the left hemisphere in 11/20. Hemispheric dominance for language was evaluated by both Wada test and fMRI using a silent word generation paradigm in all patients. Furthermore, a postictal speech test was performed in 15 patients. An fMRI language lateralization index was calculated from the number of activated pixels (Student's t test, P < 0.0001) in the right and left hemispheres. The Wada test showed a right hemispheric dominance in 8 patients (6 were left handed and 2 right handed) and a left hemispheric dominance in 12 patients (5 were left handed and 7 right handed). These results were concordant with clinical postictal examination in 11/15 patients (73%). Clinical status did not allow a conclusion about hemispheric dominance for the remaining 4 patients. FMRI was concordant with the Wada test in 19/20 cases. For one left-handed patient, fMRI showed bilateral activation, whereas the Wada test demonstrated a right hemispheric dominance. Right language lateralization was significantly correlated with left lateralized epilepsy (P < 0.05) but was not correlated with age at epilepsy onset, early brain injury (before 6 years), and lobar localization of epileptogenic focus. However the lack of a significant relationship between these factors and atypical language lateralization may be related to the small sample size.

Visualization and measurement of the cortical surface.

Much of the human cortical surface is obscured from view by the complex pattern of folds, making the spatial relationship between different surface locations hard to interpret. Methods for viewing large portions of the brain's surface in a single flattened representation are described. The flattened representation preserves several key spatial relationships between regions on the cortical surface. The principles used in the implementations and evaluations of these implementations using artificial test surfaces are provided. Results of applying the methods to structural magnetic resonance measurements of the human brain are also shown. The implementation details are available in the source code, which is freely available on the Internet.