Metabolic correlates of cognitive impairment in mesial temporal lobe epilepsy.

PURPOSE: The purpose of the study was to determine the correlations between brain metabolism and cognitive impairment in patients with drug-resistant mesial temporal lobe epilepsy (MTLE). METHODS: [18F]-FluoroDeoxyGlucose positron emission tomography ([18F]-FDG-PET) and neuropsychological assessment were performed in 97 patients with MTLE (53 females, 15-56 years old, mean: 31.6 years, standard deviation (SD) = 10.4) with unilateral hippocampal sclerosis (HS, 49 left). We compared brain metabolism and gray matter volume (GMV) between patients with cognitive impairment (intelligence quotient (IQ) and memory index <80) and patients with normal cognition, using statistical parametric mapping (SPM), in the whole population then in right and left HS (RHS, LHS) separately. RESULTS: Intelligence quotient (40-121, mean: 83.7 ±â€¯16.9) and memory index (45-133, mean: 80.7 ±â€¯19.3) were impaired in 43% and 51% of the patients, respectively, similarly in RHS and LHS. We did not find any correlations between IQ and clinical factors related to epilepsy; however, there was a significant correlation between low memory index and early age of onset in LHS (p = 0.021), and widespread epileptogenic zone in the whole population (p = 0.033). Impaired IQ correlated with extratemporal hypometabolism, involving frontoparietal networks implicated in the default mode network (DMN), predominantly in the midline cortices. Metabolic asymmetry regarding HS lateralization included the precuneus (pC) in LHS and the anterior cingulate cortex (ACC) in RHS, both areas corresponding to key nodes of the DMN. Memory index correlated with the same frontoparietal networks as for IQ, with an additional involvement of the temporal lobes, which was ipsilateral in RHS and contralateral in LHS. A diffuse decrease of GMV including the ipsilateral hippocampus correlated with cognitive impairment; however, the structural alterations did not match with the hypometabolic areas. CONCLUSIONS: Cognitive impairment in MTLE correlates with extratemporal hypometabolism, involving the mesial frontoparietal networks implicated in the DMN and suggesting a disconnection with the affected hippocampus. Asymmetric alterations of connectivity may sustain the predominant ACC and pC metabolic decrease in patients with cognitive impairment.

Stereotactic thermocoagulation for insular epilepsy: Lessons from successes and failures.

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.

18F-FDG PET in drug-resistant epilepsy due to focal cortical dysplasia type 2: additional value of electroclinical data and coregistration with MRI.

PURPOSE: To assess the localizing value of 18F-FDG PET in patients operated on for drug-resistant epilepsy due to focal cortical dysplasia type 2 (FCD2). METHODS: We analysed 18F-FDG PET scans from 103 consecutive patients (52 males, 7-65 years old) with histologically proven FCD2. PET and MRI data were first reviewed by visual analysis blinded to clinical information and FCD2 location. The additional value of electroclinical data and PET/MRI coregistration was assessed by comparison with pathological results and surgical outcomes. RESULTS: Visual analysis of PET scans showed focal or regional hypometabolism corresponding to the FCD2 in 45 patients (44%), but the findings were doubtful or misleading in 37 patients and negative in 21. When considering electroclinical data, positive localization was obtained in 73 patients, and this increased to 85 (83%) after coregistration of PET and MRI data. Under the same conditions, MRI was positive in 61 patients (59%), doubtful in 15 and negative in 27. The additional value of PET was predominant in patients negative or doubtful on MRI, localizing the FCD2 in 35 patients (83%). Interobserver agreement correlated with the grade of hypometabolism: it was good in patients with mild to severe hypometabolism (82-95%), but moderate in those with subtle/doubtful hypometabolism (45%). The main factors influencing positive PET localization were the grade of hypometabolism and the size of the FCD2 (P < 0.0001). Misleading location (nine patients) was associated with a small FCD2 in the mesial frontal and central regions. Following limited cortical resection mainly located in extratemporal areas (mean follow-up 5.6 years), a seizure-free outcome was achieved in 94% of patients, including Engel's class IA in 72%. CONCLUSION: In this series, 18F-FDG PET contributed to the localization of FCD2 in 83% of patients. This high localizing value was obtained by integration of electroclinical data and PET/MRI coregistration. This approach may help improve the surgical outcome in extratemporal epilepsy, even in patients negative on MRI.

Correction to: 18F-FDG PET in drug-resistant epilepsy due to focal cortical dysplasia type 2: additional value of electroclinical data and coregistration with MRI.

The original version of this article has added numbers in the text which are unnecessary. Correct line should be: "We also performed PET/MRI based surgical resections in an increasing number of MRI negative/ doubtful cases with favourable outcome."

Behavioral and fMRI responses to fearful faces are altered in benign childhood epilepsy with centrotemporal spikes (BCECTS).

OBJECTIVE: We hypothesized that children with benign childhood epilepsy with centrotemporal spikes (BCECTS) might have altered social cognitive skills and underlying neural networks. METHODS: We studied 13 patients with BCECTS and 11 age-matched controls using event-related functional magnetic resonance imaging (fMRI) with an emotional discrimination task consisting of viewing happy, fearful, scrambled, and neutral faces. Behavioral performance measured during the task was correlated with clinical variables and behavioral ratings. RESULTS: In comparison with age-matched controls, children with BCECTS performing a fearful faces detection task showed significantly reduced bilateral fMRI activation in the insular cortex, caudate, and lentiform nuclei, as well as increased response time. The percentage of errors made by children with BCECTS correlated negatively with age, a finding not observed in controls. In patients, accuracy positively correlated with time since the last seizure. The above abnormalities were not observed during happy faces detection task, except for a slower response in children with BCECTS as compared to controls. SIGNIFICANCE: Our study suggests that BCECTS is associated with altered social cognition network and function, particularly for the identification of fearful faces. The age dependency of some of these findings supports the view that a delayed maturation of spiking cortical regions might underlie the cognitive dysfunction observed in BCECTS.

Intelligence quotient improves after antiepileptic drug withdrawal following pediatric epilepsy surgery.

OBJECTIVE: Antiepileptic drugs (AEDs) have cognitive side effects that, particularly in children, may affect intellectual functioning. With the TimeToStop (TTS) study, we showed that timing of AED withdrawal does not majorly influence long-term seizure outcomes. We now aimed to evaluate the effect of AED withdrawal on postoperative intelligence quotient (IQ), and change in IQ (delta IQ) following pediatric epilepsy surgery. METHODS: We collected IQ scores of children from the TTS cohort with both pre- and postoperative neuropsychological assessments (NPAs; n = 301) and analyzed whether reduction of AEDs prior to the latest NPA was related to postoperative IQ and delta IQ, using linear regression analyses. Factors previously identified as independently relating to (delta) IQ, and currently identified predictors of (delta) IQ, were considered possible confounders and used for adjustment. Additionally, we adjusted for a compound propensity score that contained previously identified determinants of timing of AED withdrawal. RESULTS: Mean interval to the latest NPA was 19.8 ± 18.9 months. Reduction of AEDs at the latest NPA significantly improved postoperative IQ and delta IQ (adjusted regression coefficient [RC] = 3.4, 95% confidence interval [CI] = 0.6-6.2, p = 0.018 and RC = 4.5, 95% CI = 1.7-7.4, p = 0.002), as did complete withdrawal (RC = 4.8, 95% CI = 1.4-8.3, p = 0.006 and RC = 5.1, 95% CI = 1.5-8.7, p = 0.006). AED reduction also predicted ≥ 10-point IQ increase (p = 0.019). The higher the number of AEDs reduced, the higher was the IQ (gain) after surgery (RC = 2.2, 95% CI = 0.6-3.7, p = 0.007 and RC = 2.6, 95% CI = 1.0-4.2, p = 0.001, IQ points per AED reduced). INTERPRETATION: Start of AED withdrawal, number of AEDs reduced, and complete AED withdrawal were associated with improved postoperative IQ scores and gain in IQ, independent of other determinants of cognitive outcome.

Determinants of brain metabolism changes in mesial temporal lobe epilepsy.

OBJECTIVE: To determine the main factors influencing metabolic changes in mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis (HS). METHODS: We prospectively studied 114 patients with MTLE (62 female; 60 left HS; 15- to 56-year-olds) with (18) F-fluorodeoxyglucose-positron emission tomography and correlated the results with the side of HS, structural atrophy, electroclinical features, gender, age at onset, epilepsy duration, and seizure frequency. Imaging processing was performed using statistical parametric mapping. RESULTS: Ipsilateral hypometabolism involved temporal (mesial structures, pole, and lateral cortex) and extratemporal areas including the insula, frontal lobe, perisylvian regions, and thalamus, more extensively in right HS (RHS). A relative increase of metabolism (hypermetabolism) was found in the nonepileptic temporal lobe and in posterior areas bilaterally. Voxel-based morphometry detected unilateral hippocampus atrophy and gray matter concentration decrease in both frontal lobes, more extensively in left HS (LHS). Regardless of the structural alterations, the topography of hypometabolism correlated strongly with the extent of epileptic networks (mesial, anterior-mesiolateral, widespread mesiolateral, and bitemporal according to the ictal spread), which were larger in RHS. Notably, widespread perisylvian and bitemporal hypometabolism was found only in RHS. Mirror hypermetabolism was grossly proportional to the hypometabolic areas, coinciding partly with the default mode network. Gender-related effect was significant mainly in the contralateral frontal lobe, in which metabolism was higher in female patients. Epilepsy duration correlated with the contralateral temporal metabolism, positively in LHS and negatively in RHS. Opposite results were found with age at onset. High seizure frequency correlated negatively with the contralateral metabolism in LHS. SIGNIFICANCE: Epileptic networks, as assessed by electroclinical correlations, appear to be the main determinant of hypometabolism in MTLE. Compensatory mechanisms reflected by a relative hypermetabolism in the nonepileptic temporal lobe and in extratemporal areas seem more efficient in LHS and in female patients, whereas long duration, late onset of epilepsy, and high seizure frequency may reduce these adaptive changes.

White matter development in children with benign childhood epilepsy with centro-temporal spikes.

Benign childhood epilepsy with centro-temporal spikes (BCECTS) is a unique form of non-lesional age-dependent epilepsy with rare seizures, focal electroencepalographic abnormalities affecting the same well delineated cortical region in most patients, and frequent mild to moderate cognitive dysfunctions. In this condition, it is hypothesized that interictal electroencepalographic discharges might interfere with local brain maturation, resulting in altered cognition. Diffusion tensor imaging allows testing of this hypothesis by investigating the white matter microstructure, and has previously proved sensitive to epilepsy-related alterations of fractional anisotropy and diffusivity. However, no diffusion tensor imaging study has yet been performed with a focus on BCECTS. We investigated 25 children suffering from BCECTS and 25 age-matched control subjects using diffusion tensor imaging, 3D-T1 magnetic resonance imaging, and a battery of neuropsychological tests including Conner's scale and Wechsler Intelligence Scale for Children (fourth revision). Electroencephalography was also performed in all patients within 2 months of the magnetic resonance imaging assessment. Parametric maps of fractional anisotropy, mean-, radial-, and axial diffusivity were extracted from diffusion tensor imaging data. Patients were compared with control subjects using voxel-based statistics and family-wise error correction for multiple comparisons. Each patient was also compared to control subjects. Fractional anisotropy and diffusivity images were correlated to neuropsychological and clinical variables. Group analysis showed significantly reduced fractional anisotropy and increased diffusivity in patients compared with control subjects, predominantly over the left pre- and postcentral gyri and ipsilateral to the electroencephalographic focus. At the individual level, regions of significant differences were observed in 10 patients (40%) for anisotropy (eight reduced fractional anisotropy, one increased fractional anisotropy, one both), and 17 (56%) for diffusivity (13 increased, one reduced, three both). There were significant negative correlations between fractional anisotropy maps and duration of epilepsy in the precentral gyri, bilaterally, and in the left postcentral gyrus. Accordingly, 9 of 12 patients (75%) with duration of epilepsy>12 months showed significantly reduced fractional anisotropy versus none of the 13 patients with duration of epilepsy≤12 months. Diffusivity maps positively correlated with duration of epilepsy in the cuneus. Children with BCECTS demonstrate alterations in the microstructure of the white matter, undetectable with conventional magnetic resonance imaging, predominating over the regions displaying chronic interictal epileptiform discharges. The association observed between diffusion tensor imaging changes, duration of epilepsy and cognitive performance appears compatible with the hypothesis that interictal epileptic activity alters brain maturation, which could in turn lead to cognitive dysfunction. However, such cross-sectional association does not demonstrate causality, and other hitherto unidentified factors could represent the common cause to part or all of the observed findings.

Visual and auditory socio-cognitive perception in unilateral temporal lobe epilepsy in children and adolescents: a prospective controlled study.

AIM: A high rate of abnormal social behavioural traits or perceptual deficits is observed in children with unilateral temporal lobe epilepsy. In the present study, perception of auditory and visual social signals, carried by faces and voices, was evaluated in children or adolescents with temporal lobe epilepsy. METHODS: We prospectively investigated a sample of 62 children with focal non-idiopathic epilepsy early in the course of the disorder. The present analysis included 39 children with a confirmed diagnosis of temporal lobe epilepsy. Control participants (72), distributed across 10 age groups, served as a control group. Our socio-perceptual evaluation protocol comprised three socio-visual tasks (face identity, facial emotion and gaze direction recognition), two socio-auditory tasks (voice identity and emotional prosody recognition), and three control tasks (lip reading, geometrical pattern and linguistic intonation recognition). All 39 patients also benefited from a neuropsychological examination. RESULTS: As a group, children with temporal lobe epilepsy performed at a significantly lower level compared to the control group with regards to recognition of facial identity, direction of eye gaze, and emotional facial expressions. We found no relationship between the type of visual deficit and age at first seizure, duration of epilepsy, or the epilepsy-affected cerebral hemisphere. Deficits in socio-perceptual tasks could be found independently of the presence of deficits in visual or auditory episodic memory, visual non-facial pattern processing (control tasks), or speech perception. A normal FSIQ did not exempt some of the patients from an underlying deficit in some of the socio-perceptual tasks. CONCLUSION: Temporal lobe epilepsy not only impairs development of emotion recognition, but can also impair development of perception of other socio-perceptual signals in children with or without intellectual deficiency. Prospective studies need to be designed to evaluate the results of appropriate re-education programs in children presenting with deficits in social cue processing.

Dissociation between Selecting and Orienting Attentional Reading Deficits: A Study in Adults with Epilepsy.

Word reading requires a range of spatial attention processes, such as orienting to a specific word and selecting it while ignoring other words. This study investigated whether deficits of these spatial attention processes can show dissociations after hemispheric lesions. Thirty-nine patients with left or right focal epilepsy and 66 healthy participants had to read aloud four-letter words presented in the left and right visual hemifields. There were three successive blocks of presentation: in the unilateral block, a single word was presented in one of the visual hemifields; in the bilateral block, two words were presented simultaneously, one in each visual hemifield; in the cued block, two words were also presented, but only the cued word had to be reported. Twenty-one patients, twelve with a left and nine with a right hemisphere lesion, showed a word reading deficit. Four had specific difficulties in the cued block, suggesting an attentional selection reading deficit. Twelve patients had an asymmetric reading deficit, suggesting an attention orientation or a visual field deficit. Five patients had more complex deficits. The visual field presentation procedure may help to reveal different types of reading disorders in patients with epilepsy and to dissociate orienting and selecting deficits.

Disengagement and inhibition of visual-spatial attention are differently impaired in children with rolandic epilepsy and Panayiotopoulos syndrome.

We assessed voluntary orientation and reorientation of visuospatial attention in 313 healthy 6- to 22-year-old participants, 30 children suffering from benign epilepsy with centrotemporal spikes (BECTS) and 13 children with Panayiotopoulos syndrome (PS). The developmental section highlights the late development of reorienting skills. Only children with BECTS-R showed a strong tendency toward a rightward bias in attentional orientation. Additionally, a unilateral deficit of disengagement characterizes the patients with BECTS-R and comorbid ADHD. Right rolandic spikes seem to aggravate subclinical reorienting difficulties. Finally, children with PS failed to diffuse inhibition, except in the nearest area outside the attentional focus. This deficit could be attributed to the typical occipital-to-frontal spreading of the spikes in PS. By showing distinct attentional deficiencies according to the epileptic syndrome and the epileptic focus lateralization in BECTS, the results provide new evidence for alterations of attentional mechanisms by interictal epileptic activity, which probably contribute to learning difficulties.

Benefits and Risks of Epilepsy Surgery in Patients With Focal Cortical Dysplasia Type 2 in the Central Region.

BACKGROUND AND OBJECTIVES: Focal cortical dysplasia type 2 (FCD2) in the central region can cause drug-resistant epilepsy for which surgery remains challenging because of subsequent functional deficits. Advances in imaging and surgical techniques have progressively improved outcome. We aimed to assess the benefits on epilepsy and the functional risks after FCD2 resections in these highly eloquent areas. METHODS: We retrospectively studied all consecutive patients with histologically confirmed FCD2 located in the central region operated on between 2000 and 2019 at a single center. We analyzed electroclinical and imaging features (including fMRI), seizure outcome, and early and late postoperative neurologic status correlating to anatomo-functional areas (primary motor cortex [PMC], paracentral lobule [PCL], supplementary motor area [SMA], precentral gyrus [PrCG], postcentral gyrus [PoCG], central operculum [COp]). RESULTS: Sixty patients (35 female, age 7-65 years) were included in the study. Epilepsy was characterized by early onset, high seizure frequency with clusters (30-90/d), drop attacks, and status epilepticus. Ictal semiology included sensory-motor auras, motor and postural manifestations, and postictal motor deficits. EEG and stereo-EEG patterns were like those typically recorded in FCD2. MRI was positive in 63% and 18F-fluorodeoxyglucose-PET was positive in 86% of the patients. fMRI demonstrated activations close to the FCD2 (59%) or minor reorganization (41%) but none within the lesion. Seizure-free outcome (2- to 20-year follow-up) was obtained in 53 patients (88%), including 37 achieving Engel class IA (62%), correlating with complete FCD2 removal. Early transitory postoperative deficits occurred in 52 patients (87%), which were severe in 19, mostly after PMC, PCL, and SMA resections, while PrCG, PoCG, and COp resections were associated with minor/moderate deficits. Total recovery was observed in 21 of 52 patients (40%), while a permanent deficit (>2 years) persisted in 31 (minor 19, moderate 9, major 3). The best outcome (seizure freedom without deficit [48%] or with minor deficit (28%]) was significantly more frequent in children (p = 0.025). Antiseizure medications were discontinued in 28 patients (47%). Quality of life correlated with seizure-free outcome and absence of postoperative deficit; 43 patients (72%) reported a schooling or socio-professional improvement. DISCUSSION: Excellent seizure outcome and low rates of major permanent disability can be achieved after central FCD2 resections despite functional risks. CLASSIFICATION OF EVIDENCE: Due to its retrospective nature, this study provides Class IV evidence that good seizure outcomes with minor additional deficits can be achieved after epilepsy surgery in the central region.

Neural correlates of verbal working memory in children with epilepsy with centro-temporal spikes.

BACKGROUND: Previous functional magnetic resonance imaging (fMRI) studies have identified brain systems underlying different components of working memory (WM) in healthy subjects. The aim of this study was to compare the functional integrity of these neural networks in children with self-limited childhood epilepsy with centro-temporal spikes (ECTS) as compared to healthy controls, using a verbal working memory task (WMT). METHODS: Functional MRI of WM in seventeen 6-to-13 year-old children, diagnosed with ECTS, and 17 sex- and age-matched healthy controls were conducted at 3 T. To estimate BOLD responses during the maintenance of low, medium, and high WMT loads, we used a Sternberg verbal WMT. Neuropsychological testing prior to scanning and behavioral data during scanning were also acquired. RESULTS: Behavioral performances during WMT, in particular accuracy and response time, were poorer in children with ECTS than in controls. Increased WM load was associated with increased BOLD signal in all subjects, with significant clusters detected in frontal and parietal regions, predominantly in the left hemisphere. However, under the high load condition, patients showed reduced activation in the frontal, temporal and parietal regions as compared to controls. In brain regions where WM-triggered BOLD activation differed between groups, this activation correlated with neuropsychological performances in healthy controls but not in patients with ECTS, further suggesting WM network dysfunction in the latter. CONCLUSION: Children with ECTS differ from healthy controls in how they control WM processes during tasks with increasing difficulty level, notably for high WM load where patients demonstrate both reduced BOLD activation and behavioral performances.

18F-FDG-PET patterns of surgical success and failure in mesial temporal lobe epilepsy.

OBJECTIVE: To search for [18F]-fluorodeoxyglucose (FDG)-PET patterns predictive of long-term prognosis in surgery for drug-resistant mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis (HS). METHODS: We analyzed metabolic data with [18F]-FDG-PET in 97 patients with MTLE (53 female participants; age range 15-56 years) with unilateral HS (50 left) and compared the metabolic patterns, electroclinical features, and structural atrophy on MRI in patients with the best outcome after anteromesial temporal resection (Engel class IA, completely seizure-free) to those with a non-IA outcome, including suboptimal outcome and failure. Imaging processing was performed with statistical parametric mapping (SPM5). RESULTS: With a mean follow-up of >6 years (range 2-14 years), 85% of patients achieved a class I outcome, including 45% in class IA. Class IA outcome was associated with a focal anteromesial temporal hypometabolism, whereas non-IA outcome correlated with extratemporal metabolic changes that differed according to the lateralization: ipsilateral mesial frontal and perisylvian hypometabolism in right HS and contralateral fronto-insular hypometabolism and posterior white matter hypermetabolism in left HS. Suboptimal outcome presented a metabolic pattern similar to the best outcome but with a larger involvement of extratemporal areas, including the contralateral side in left HS. Failure was characterized by a mild temporal involvement sparing the hippocampus and relatively high extratemporal hypometabolism on both sides. These findings were concordant with electroclinical features reflecting the organization of the epileptogenic zone but were independent of the structural abnormalities detected on MRI. CONCLUSIONS: [18F]-FDG-PET patterns help refine the prognostic factors in MTLE and should be implemented in predictive models for epilepsy surgery.

Cognitive impairments in children with nonidiopathic temporal lobe epilepsy.

Ictal and interictal activities occurring in a mature brain can disorganize the neural network activity involved in one or various specific cognitive processes. In children, the situation might be more complex: the epileptic process occurs in a period when the cortex is still maturing and it may interfere with normal cerebral development. Although neural plasticity in children is greater than it is in adults, greater plasticity does not necessarily mean adaptive plasticity. Studies have shown that temporal lobe epilepsy in children is not systematically associated with global mental retardation. However, various difficulties in specific cognitive domains are more often found in children than in patients with adult-onset epilepsy. Language, memory, socioperceptive competence, and also executive functions, which can be impaired by the disruption of the temporofrontal circuit, are among such cognitive functions that need to be evaluated. Early detection of specific deficits is of primary importance for the implementation of appropriate remediation measures.

Nonidiopathic focal epilepsies: methodological problems for a comprehensive neuropsychological evaluation.

In aiming to define better practice parameters for neuropsychological assessment in patients with nonidiopathic partial epilepsies, particularly in children, we discuss the reasons for the current lack of clear answers. The relevant factors include the epilepsy itself, the complexity of the issues related to cognitive function/dysfunction and the underlying developmental processes. Another factor is the lack of availability and high cost of neuropsychological testing, even in industrialized societies. Because of these factors, the need for neuropsychological testing must be considered on an individual basis in the initial evaluation of every child with focal epilepsy; it should be left to the clinician and parents to decide which children will actually be referred. Systematic presurgical and postsurgical testing is important for surgical candidates. Comprehensive research protocols should be designed on a collaborative basis between large epilepsy centers, covering all the essential parameters to be evaluated. Children with focal epilepsies should be included in these protocols from the onset of the epilepsy.

Early brain lesions and face-processing development.

Studies of functional plasticity after pre- or perinatal brain damage can tell us whether the neural substrate normally involved in the development of a given ability is specific and, if so, when it becomes functionally specified and unique. Development of face processing was investigated in 5- to 17-year-old children who had a unilateral brain injury in the pre-, peri-, or postnatal period. In Studies 1 and 2, patients with a posterior injury involving the temporal regions exhibited a face-processing deficit that was independent of their age at test time. Even though differences were observed between the two hemispheres in face processing during infancy as well as in adults in cases of normal development, no clear differences between right and left injury were observed here in face-processing deficit. Poor postlesional face-processing plasticity seems to contrast with results of several studies on speech development after early unilateral injury. If the difference in the time window for postlesional plasticity between these two areas of competency is confirmed, it would suggest that the two kinds of abilities rely on neural cells which are sensitive to different plasticity factors.