Intracarotid amobarbital testing for language and memory dominance in children

Pediatric epilepsy surgery

Medically refractory epilepsy is a significant cause of morbidity and mortality in pediatric neurology. Surgical intervention has been well established as a viable treatment option in certain cases. This article reviews the process of selecting appropriate patients using the latest advances in neuroimaging and electrophysiologic techniques. It also discusses the various surgical techniques currently available, including recent advances in minimally invasive approaches.

Surgery for childhood epilepsy

Approximately 60% of all patients with epilepsy suffer from focal epilepsy syndromes. In about 15% of these patients, the seizures are not adequately controlled with antiepileptic drugs; such patients are potential candidates for surgical treatment and the major proportion is in the pediatric group (18 years old or less). Epilepsy surgery in children who have been carefully chosen can result in either seizure freedom or a marked (>90%) reduction in seizures in approximately two-thirds of children with intractable seizures. Advances in structural and functional neuroimaging, neurosurgery, and neuroanaesthesia have improved the outcomes of surgery for children with intractable epilepsy. Early surgery improves the quality of life and cognitive and developmental outcome and allows the child to lead a normal life. Surgically remediable epilepsies should be identified early and include temporal lobe epilepsy with hippocampal sclerosis, lesional temporal and extratemporal epilepsy, hemispherical epilepsy, and gelastic epilepsy with hypothalamic hamartoma. These syndromes have both acquired and congenital etiologies and can be treated by resective or disconnective surgery. Palliative procedures are performed in children with diffuse and multifocal epilepsies who are not candidates for resective surgery. The palliative procedures include corpus callosotomy and vagal nerve stimulation while deep brain stimulation in epilepsy is still under evaluation. For children with "surgically remediable epilepsy," surgery should be offered as a procedure of choice rather than as a treatment of last resort.

Language mapping in temporal lobe epilepsy in children: special considerations

Temporal lobe epilepsy (TLE) in children is a slightly different entity than TLE in adults not only because of its semiology and pathology but also because of the different approach to surgical treatment. Presurgical investigations for eloquent cortex, especially language, must take these differences into account. Most diagnostic tests were created for adults, and many of the assessment tools need to be adapted for children because they are not just small adults. This paper will highlight the specific challenges and solutions in mapping language in a pediatric population with TLE.

Temporal lobe epilepsy in children

The temporal lobe is a common focus for epilepsy. Temporal lobe epilepsy in infants and children differs from the relatively homogeneous syndrome seen in adults in several important clinical and pathological ways. Seizure semiology varies by age, and the ictal EEG pattern may be less clear cut than what is seen in adults. Additionally, the occurrence of intractable seizures in the developing brain may impact neurocognitive function remote from the temporal area. While many children will respond favorably to medical therapy, those with focal imaging abnormalities including cortical dysplasia, hippocampal sclerosis, or low-grade tumors are likely to be intractable. Expedient workup and surgical intervention in these medically intractable cases are needed to maximize long-term developmental outcome.

Approach to pediatric epilepsy surgery: State of the art, Part I: General principles and presurgical workup

In 1990, the National Institute of Health adopted epilepsy surgery in children as an option when medications fail. In the past few years several concepts have become increasingly recognized as key to a successful approach to epilepsy surgery in children. These include the concepts of neuronal plasticity, the epileptogenic lesion, the ictal onset, symptomatogenic, irritative, and epileptogenic zones. In addition, several techniques have increasingly been utilized to delineate the above areas in an attempt to determine, in each patient, the epileptogenic zone, defined as the zone the resection of which leads to seizure freedom. When seizure semiology (which defines the symptomatogenic zone), ictal EEG (which identifies the ictal onset zone), and structural imaging (which identifies the epileptogenic lesion) can be reconciled to infer the location of the epileptogenic zone, surgery is usually, subsequently, undertaken. When these diagnostic modalities are discordant, not definitive, or when the epileptogenic zone is close to eloquent cortex, invasive EEG, complemented by other imaging techniques may be needed. These include magnetoencephalography, single photon emission tomography, various types of positron emission tomography, various magnetic resonance imaging modalities (functional, diffusion weighted, other) and other emerging and experimental techniques. While MRI, video-EEG, and neuropsychological assessments are well established components of the presurgical evaluation, the use of the new emerging imaging technologies is dictated by the degree of anatomo-electro-clinical correlations, and, awaiting multicentric studies and more detailed guidelines, remains center-dependent.

Prediction of Verbal Memory Decline after Epilepsy Surgery in Children: Effectiveness of Wada Memory Asymmetries

PURPOSE

Differences in Wada memory performance after left and right amobarbital injection are powerful predictors of pre- to postoperative memory change among adult epilepsy patients after anterior temporal lobectomy. It is unknown, however, whether these Wada memory asymmetries apply to children who undergo focal cortical resection or to epilepsy surgery patients who undergo resection outside the temporal lobes.

METHODS

To investigate these issues, Wada memory asymmetries and pre- to postoperative neuropsychological memory test performances were examined in 132 children who underwent some form of resective epilepsy surgery. Ninety-three (70%) children showed Wada memory asymmetries in the predicted direction (memory after injection ipsilateral to side of surgery better than memory after contralateral injection), and 39 (30%) did not.

RESULTS

Children with Wada memory asymmetries showed significant improvement in verbal memory after surgery as compared with children without Wada memory asymmetries who showed significant verbal memory decline. This result was also obtained when individual cases were examined: 77% of children with Wada memory asymmetries in predicted direction showed no verbal memory decline after surgery, whereas 80% of children without asymmetries had lower postoperative verbal memory (passage recall) test scores. Wada memory asymmetries had no value in predicting postoperative changes in visual-spatial memory.

CONCLUSIONS

Wada memory asymmetries may be used as one of the factors to assess risk for verbal memory decline after epilepsy surgery in children.

Factors associated with atypical speech representation in children with intractable epilepsy

The purpose of this study was to investigate the relationship between hemispheric speech dominance and several demographic and seizure variables in a large sample of children (N=75) who underwent the intracarotid amobarbital procedure (IAP) prior to surgery. The findings were similar to results previously reported in adults and children, suggesting that variables, such as age at seizure onset, laterality of seizure focus, location of seizure focus and handedness are related to the presentation of atypical speech representation in children with epilepsy. The impact of multiple variables in determining the risk for atypical speech dominance was also assessed. The results demonstrated an increased probability of atypical speech representation in children with a greater number of risk variables, suggesting the need for further investigations in this area.

Clinical and neuropsychological characteristics of pediatric epilepsy patients with atypical language dominance

Studies on intracarotid amobarbital procedures (IAP) in pediatric patients are rare and mainly focus on practicability aspects. Very few studies have reported characteristics of children with atypical language dominance. We compared children with left-sided focal epilepsy and atypical (i.e., right or bilateral) versus left-sided language representation (n=12 versus 17). Our results indicate a higher incidence of left handedness, extratemporal lesions, an earlier onset of epilepsy, and a neuropsychological "crowding effect" with distinct nonverbal memory deficits in the atypical group. We conclude that atypical language representation in children with left-sided epilepsy is associated with similar characteristics as in adults. It is recommended that the possibility of a language shift in the presurgical workup of pediatric patients be considered, particularly if a left-hemispheric epileptic focus is suspected.

Wada memory performance predicts seizure outcome after epilepsy surgery in children

PURPOSE

Wada memory asymmetries were examined in children from four comprehensive epilepsy surgery centers who subsequently underwent epilepsy surgery to determine whether Wada memory performance could predict degree of seizure relief in children.

METHODS

One hundred fifty-six children (between ages 5 and 16 years) with intractable epilepsy underwent Wada testing before resective epilepsy surgery (93 within the left hemisphere, and 63 within the right hemisphere). Memory stimuli were presented soon after intracarotid amobarbital injection, and recognition memory for the items was assessed after return to neurologic baseline. Eighty-eight children underwent unilateral temporal lobe resection, and 68 had extratemporal lobe resections. One hundred four (67%) children were seizure free (Engel class I), and 52 (33%) were not seizure free (Engel classes II-IV) at follow-up (mean follow-up interval, 2.3 years).

RESULTS

Seizure-free children recalled 19.3% more Wada memory items after ipsilateral injection than did non-seizure-free children (p = 0.008). If analysis was restricted to youngsters with temporal lobectomies (TLs), seizure-free children recalled 27.7% more items after ipsilateral injection than did non-seizure-free TL children (p = 0.004). With regard to individual patient prediction, 75% of children who had memory score asymmetries consistent with the seizure focus were seizure free. In contrast, only 56% of children whose memory score asymmetries were inconsistent with the seizure focus were seizure free (p = 0.01).

CONCLUSIONS

Results suggest that Wada memory performance asymmetries are related to the degree of seizure relief after epilepsy surgery in children and adolescents.

Effect of Wada methodology in predicting lateralized memory impairment in pediatric epilepsy surgery candidates

Because Wada evaluations are not standardized, it is impossible to know to what degree method variance accounts for reported differences in results. To examine this problem, three comprehensive epilepsy surgery centers compared the efficacy of two Wada memory methods to predict seizure onset laterality in 152 children being considered for epilepsy surgery. Wada memory asymmetries were evaluated using either real objects with no verbal response required or more mixed stimuli requiring a verbal response. When using real objects, Wada memory performance was significantly worse when relying on the side of seizure onset in both left and right seizure onset children. In contrast, Wada memory performance using mixed stimuli was worse on the side of seizure onset only among patients with seizures originating in the left-hemisphere. The superiority of real objects was most apparent in younger children with left side seizure onset. Results suggest the use of mixed stimuli is less sensitive to the effects of unilateral seizure onset, and thus, diminishes the capacity of the Wada test to predict lateralized seizure onset in children.

Surgical treatment of epilepsy

Approximately 30-40% of patients with focal epilepsy continue to have seizures despite appropriate medical therapy. Surgical treatments should be considered in this important subset of patients. Recent advances in neuroimaging technology have revolutionized the identification and evaluation of surgical candidates. The goal of the presurgical evaluation (video EEG monitoring, neuroimaging, and neuropsychological assessment) is to delineate the epileptogenic zone. Surgery is recommended when this has been adequately identified and the proposed procedure is expected to result in a high likelihood of seizure freedom and a low risk of neurologic and cognitive morbidity.

Focal functional deficits in temporal lobe epilepsy on PET scans and the intracarotid amobarbital procedure: comparison of patients with unitemporal epilepsy with those requiring intracranial recordings

PURPOSE

To analyze the relationship between the intracarotid amobarbital procedure (IAP) and positron emission tomography (PET) and study the lateralizing value of these tests in patients with unitemporal epilepsy and those requiring intracranial recordings.

METHODS

We compared 51 patients with unitemporal epilepsy (group1) with 26 patients in whom surface recordings failed to reveal a distinct unitemporal focus, necessitating invasive recordings (group 2).

RESULTS

The brain magnetic resonance imaging (MRI) scans for group 1 showed mesial temporal sclerosis in 70.5% of the patients. PET showed unilateral temporal hypometabolism in 88%. In addition, 74.5% of the patients in group 1 had impaired memory on the epileptogenic side on the IAP, and 89.4% of those patients also had ipsilateral temporal hypometabolism on PET scans. All the group 1 patients underwent temporal resections. The pathologic examination showed hippocampal sclerosis in 72% of the patients. Eighty percent of group 1 patients became seizure free, and 16% had rare seizures (follow-up, 2-7 years). MRIs for group 2 showed mesial temporal sclerosis in 31% of the patients; PET scans showed temporal hypometabolism in 39%. The IAP was lateralized in 47.8%. Sixty-nine percent had temporal lobe resections. The pathologic examination showed hippocampal sclerosis in 44% of the patients. Forty-four percent of group 2 patients became seizure free, and 27.7% had rare seizures (follow-up, 2-8 years).

CONCLUSIONS

Ninety-six percent of the patients with unitemporal foci had focal functional deficits on the epileptogenic side on 18-fluorodeoxyglucose-(FDG) PET scans, the IAP, or both. The results of the FDG-PET were predictive of impaired memory on the IAP. Memory impairment contralateral to the temporal hypometabolism found on the PET scans was never seen. These patients had an excellent outcome. In contrast, <50% of the patients requiring intracranial recordings had focal functional deficits, suggesting that more a diffuse pathology may account for their less favorable outcome.

Selection and evaluation of children for epilepsy surgery

Major determinants of the success of epilepsy surgery are the proper selection and evaluation of the patient. Candidates should have medically intractable, disabling epilepsy. The evaluation requires a unified, systematic approach by a comprehensive team of health professionals. Key points, common to most evaluations, are enumerated and provide a useful tool for mental organization. In general, the greater the degree of congruent information derived from these investigations, the better the candidacy for surgery. After this, completeness of resection and etiology are other important predictors of success. Children present unique challenges and opportunities owing to the vulnerability and plasticity of the developing nervous system. Surgery for intractable epilepsy can be a rewarding therapy, and in select children, the only chance for cure and substantial development progress.

Epilepsy surgery in children with developmental disabilities

Surgery for treatment of medically uncontrolled epilepsy in children is now widely accepted with reported outcomes similar to those in adults. Epilepsy is reported in 8.8% to 32% of children with mental retardation (MR) and in up to half of children with severe retardation. There has been concern that patients with low IQ will experience unsatisfactory outcomes from epilepsy surgery and not achieve good seizure control. It is appropriate to reassess the prior bias against resective epilepsy surgery in children with MR in view of the changing criteria for potential candidacy for epilepsy surgery in infants and young children. There are three prerequisites for epilepsy surgery: (1) the epilepsy must be medically intractable; (2) the surgery must be feasible, that is, the epileptogenic zone can identified and safely resected; and (3) there is high likelihood of a satisfactory outcome as regards both the epilepsy and the patient's functional status. Patients with MR may have diffuse cerebral dysfunction and diffuse or multifocal epileptogenic regions. Appropriate patient selection is made possible through use of current technology that allows identification of lesions or areas of cerebral dysgenesis, aiding in identification of localized areas of epileptogenesis. Results from various series of patients with MR who have undergone resective surgery for epilepsy have shown that with careful presurgical evaluations, outcomes are similar between patients with normal IQ scores and those with low scores. Surgical protocols specifically for patients with MR and intractable epilepsy are required, including careful definition of desired outcomes.

Epilepsy surgery in children, with special attention to focal cortical resections

Epilepsy surgery is an important alternative for children and adolescents with medically intractable epilepsy. Advances in imaging have allowed the visualization of epileptogenic regions, including cortical dysplasia. The presurgical evaluation will likely become less invasive as imaging technology improves. Long-term development is a critical outcome measure, in addition to seizure control. The long-term prognosis after epilepsy surgery may be related to factors other than seizure control, including the timing of the intervention and the cause of the epilepsy. It may be useful to independently analyze children based on cause, and further studies examining the long-term outcome should become feasible as surgical experience grows.

Risk factors for unsuccessful testing during the intracarotid amobarbital procedure in preadolescent children

PURPOSE

Identification of risk factors for unsuccessful testing during intracarotid amobarbital procedure (IAP) in preadolescent children.

METHODS

A pediatric IAP protocol was attempted in 42 candidates for epilepsy surgery (5-12 years old; mean, 10 years) based on the ability to pass a practice test. Language dominance was defined by marked asymmetry until first verbal response and paraphasic errors. Intact hemispheric memory was defined by recall of >/=60% of test items. The odds ratios of baseline variables (age at IAP, Full-Scale IQ, side of disease, age at seizure onset, amobarbital dose) were calculated for various IAP outcomes.

RESULTS

IAPs were accomplished in 40 children. Language dominance was established in 25 (62.5%) of 40 patients: all 21 focal resection candidates were left language dominant; four hemispherectomy candidates had intact language after injection of the damaged hemisphere. In 12 (30%) of 40 patients, language testing failed because of agitation or obtundation. Compared with the 21 children with language dominance established by bilateral IAP, these 12 children had lower mean Full-Scale IQ (66.4 vs. 87.9; p = 0.014), and more frequently, the epileptogenic lesion in the left hemisphere (presumed dominant by right-handedness; 78 vs. 33%; p = 0.04). Excluding hemispherectomy candidates (intentionally only one injection), memory testing could not be completed in 13 (36%) of 36 children because of obtundation or agitation. These children were significantly younger than the 23 (64%) of 36 with successful bilateral memory testing (mean age, 107.6 vs. 128.7 months; p = 0. 006). The eight (25%) of 32 children with failing retention scores after ipsilateral injection had lower Full-Scale IQ than did the 24 (75%) patients who passed (mean, 59.6 vs. 81.7 months; p = 0.03).

CONCLUSIONS

The IAP successfully established hemispheric language dominance and memory representation for just under two thirds of the preselected preadolescent children. Risk factors for unsuccessful testing included low Full-Scale IQ (especially <80), young age (especially <10 years), and seizures arising from the left hemisphere presumed dominant by right-handedness.

Is speech arrest during wada testing a valid method for determining hemispheric representation of language?

BACKGROUND AND OBJECTIVE

The intracarotid amobarbital procedure, or Wada test, is the method of choice to determine hemispheric representation of language, and is routinely used in the presurgical evaluation for intractable epilepsy. Some investigators perform comprehensive language assessments, but others base language lateralization solely on speech arrest. This study sought to determine whether speech arrest alone during Wada testing provides valid data regarding language lateralization.

METHODS

The subjects (previously reported) were 21 patients evaluated for intractable epilepsy, who underwent language lateralization by Wada testing and functional MRI (FMRI). For each patient, language representation was determined by calculating: (1) a Wada laterality index based exclusively on speech arrest; (2) a Wada laterality index based on comprehensive language assessment; and (3) an FMRI laterality quotient. Correlation coefficients and categorical classifications were analyzed.

RESULTS

There was no significant correlation between the Wada laterality quotient derived from duration of speech arrest and either the comprehensive Wada language laterality score (r =.35, p =.12) or FMRI language laterality score (r =.32, p =.16). Categorical classification as left, right or bilateral language also showed marked discordance between speech arrest and the other two methods.

CONCLUSION

Duration of speech arrest during Wada testing is not a valid measure of language dominance.

Seizure outcome after epilepsy surgery in children and adolescents

Few epilepsy surgery outcome data are available from series of pediatric patients. We studied seizure outcome in 136 pediatric patients who had surgery for intractable epilepsy at The Cleveland Clinic between January 1990 and June 1996, with a postoperative follow-up of 1 to 7.5 years (mean, 3.6 years). Sixty-two children (3 months to 12 years old at time of surgery) were compared with 74 adolescents (13-20 years old). Extratemporal or multilobar resections and hemispherectomies were similarly frequent among children (50%) and adolescents (44%), but these procedures strongly predominated in infancy (90% of patients 0-2 years of age). The remaining patients had temporal resection. Cortical dysplasia and low-grade tumor were the most common causes and hippocampal sclerosis was rare. Seizure-free outcome was achieved for 69% of adolescents, 68% of children, and 60% of the infant subgroup, overall; for 23 (74%) of 31 children and 33 (80%) of 41 adolescents after temporal resection; for 11 (58%) of 19 children and 15 (52%) of 29 adolescents after extratemporal or multilobar resection; and for 8 (67%) of 12 children and 3 (75%) of 4 adolescents after functional hemispherectomy. Seizure-free outcome was more frequent after temporal resection (56 of 72, 78%) than after extratemporal or multilobar resection (26 of 48, 54%; 41 of 48 with a focal lesion on magnetic resonance imaging), and among patients with tumor (36 of 44, 82%) versus cortical dysplasia (16 of 31, 52%). The frequency of seizure-free outcome after epilepsy surgery was similar for infants, children, and adolescents, and comparable with results from adult series. Most patients in each age, surgery type, and causal group were free from seizures after surgery. These results suggest that children should be considered for surgical evaluation at whatever age they manifest with severe, intractable, disabling localization-related epilepsy.

Surgical treatment of epilepsy in children

In carefully selected children, as well as adults, intractable seizures may be eliminated or greatly reduced by cortical resection or hemispherectomy. Critical features of surgical candidacy include intractable disabling epilepsy, a localized epileptogenic zone, and a low risk of new postoperative deficits; however, the analysis may be complicated in children. Compared with adults, pediatric patients are especially likely to present with poorly localizing electroencephalographic features because of their high incidence of extratemporal localization and developmental pathology. Maturation factors may result in unusual epilepsy manifestations, for example, infantile spasms and hypsarrhythmia caused by a focal cortical lesion. The cognitive and psychosocial costs of continued frequent seizures during infancy and childhood must be assessed differently from those in adults and may include stagnation of developmental progression. The risk for new postoperative deficits may be modified if surgery is performed during stages of active brain maturation with developmental plasticity. For each individual child, the potential risk/benefit ratio for surgery must be carefully weighed on the basis of results of an extensive preoperative evaluation. Results from pediatric epilepsy surgery series are encouraging, with percentages of seizure-free patients similar to those in adult series. In some series, delaying surgery for childhood-onset epilepsy into adulthood was associated with greater permanent psychosocial, behavioral, and educational problems. The available data suggest that children should be considered for surgical evaluation at whatever age they present with severe intractable localization-related epilepsy. Complicated cases warrant referral to specialized centers with extensive pediatric epilepsy surgery experience.

Neuropsychological effect of temporal lobe resection in preadolescent children with epilepsy

PURPOSE

Numerous studies have demonstrated changes in cognitive, memory, and language functioning in adults and adolescents after temporal lobectomy, yet little information is available regarding neuropsychological outcome in preadolescent children.

METHODS

We studied pre- and postoperative neuropsychological test results from 14 children who underwent temporal lobe resection for intractable epilepsy at age 7-12 years (mean 9.4 years).

RESULTS

Thirteen patients (93%) had no seizures or less than one seizure a year at follow-up 23-48 months (mean 34 months) after operation. Postoperative neuropsychological testing was performed 6-9 months (mean 7 months) after surgery in 13 patients and 36 months after the first operation in 1 patient who underwent two-stage resection of a tumor. Verbal, Performance, and Full Scale IQ were initially in the low-average range, with no significant change across the pre- and postoperative evaluations. Immediate verbal memory performance decreased significantly in children who initially performed above the median preoperatively and tended to decrease in children who had left rather than right temporal lobe resection. Significant postoperative decreases in delayed memory scores were independent of preoperative ability or side of resection.

CONCLUSIONS

Our small study suggests vulnerability to postoperative decline in immediate verbal memory scores in preadolescent children who have higher baseline immediate memory function or undergo left rather than right temporal lobe resection, similar to that observed in adolescents in adults. The entire group exhibited a statistically significant decrease in delayed verbal memory. Study of larger series of patients will be important to clarify further the short- and long-term risks and benefits of temporal lobe resection in childhood.

Use of the intracarotid amobarbital procedure in the evaluation of memory

The intracarotid amobarbital procedure (IAP) involves the temporary inactivation of one cerebral hemisphere by the injection of sodium amobarbital, which allows independent testing of the contralateral hemisphere. Initially used for lateralization of language, IAP later found a role in the evaluation of memory function in patients with intractable temporal lobe epilepsy being considered for resective surgery. IAP technique varies widely across centers, but, in general, memory is assessed by presenting the patient with a number of items during the period of hemispheric inactivation and testing recall or recognition of these items after the effect of the drug has worn off. Because the medial temporal lobe is not directly perfused by the internal carotid artery, concerns have been raised about the ability of the IAP to test hippocampal memory function. Consequently, a variety of selective procedures have been devised. Findings on both intracranial EEG recordings and pathologic and neuroimaging studies support the association of IAP memory results with hippocampal function. The IAP memory test was originally designed to predict the risk for development of global amnesia following unilateral temporal lobectomy. More recently, it also has been used as an adjunct in lateralizing the seizure focus and for predicting postoperative selective memory deficits and seizure outcome.

Language cortex representation: effects of developmental versus acquired pathology

Relatively little is known about language cortex representation in patients with developmental pathology and epilepsy. We report the results of mapping language by electrical stimulation of chronically implanted subdural electrodes in 34 patients (mean age, 12.2 years) evaluated for epilepsy surgery, 28 of whom had magnetic resonance imaging or histological evidence of developmental tumors or cortical dysplasia. Language cortex was identified in the temporal or frontal lobe of 19 patients (left hemisphere in 17, right hemisphere in 2), and overlapped or bordered the epileptogenic region in 12. Language cortex was not found in the frontal or temporal lobe of 15 patients (left hemisphere in 4, right hemisphere in 11) and was presumed to be contralateral to grid placement. Three patients with left-hemisphere perinatal or postnatal cerebral insults before the age of 5 years had no language in the left hemisphere, while 3 patients with insults between the ages of 6 and 16 years had preserved left-hemisphere language. Developmental lesions and early-onset seizures do not displace language cortex from prenatally determined sites, whereas lesions acquired before the age of 5 years may cause language to relocate to the opposite hemisphere, but only when language cortex is destroyed.

[Problems related to neurosurgical treatment of epilepsy in children]

Neurosurgery of epilepsy in children has undergone rapid development during the past decade. This was justified by the high incidence of intractable epilepsy and its consequences on cognitive development. Any decision in the area of surgery must take in account specific etiology and the rapid maturation of the infant's brain. As in adulthood, both the epileptogenic and the functional zones must be identified, but this is a challenge when the brain is not mature and the functions not yet developed. In addition, the ability to recover must be determined. At the present time no precise methodology can be advised for presurgical work-up and surgical indications.

Temporal lobe epilepsy in early childhood

To explore the electroclinical features of temporal lobe epilepsy (TLE) in early childhood, we studied results of video-EEG and other tests of 14 children aged 16 months to 12 years selected by seizure-free outcome after temporal lobectomy. Four children had mesiotemporal sclerosis, 1 had cortical dysplasia, and 9 had low-grade temporal neoplasms. The children had complex partial seizures (CPS) with symptomatology similar to that of adults with TLE, including decreased responsiveness and automatisms. Automatisms tended to be simpler in the younger children, typically limited to lip smacking and fumbling hand gestures. Scalp/sphenoidal EEG showed anterior/inferior temporal interictal sharp waves and unilateral temporal seizure onset in the 4 children with mesiotemporal sclerosis and in the child with cortical dysplasia, but EEG findings in 9 children with low-grade temporal tumors were complex, including multifocal interictal sharp waves or poorly localized or falsely lateralized EEG seizure onset. In children without tumors, video-EEG was critical to localization of the epileptogenic zone for resection, but in patients with tumors video-EEG was less localizing and its main value was to confirm that the reported behaviors were epileptic seizures with semiology typical of temporal lobe onset.