Significance of postoperative electroencephalograms in patients with extratemporal lesional epilepsy

We retrospectively studied EEGs performed 1 week, 3 months, and 1 year after surgery (lesionectomy or lesion resection with corticectomy) in 24 patients with extratemporal lesional epilepsy who had a mean duration of follow-up of 2.5 years. All patients had intractable partial seizures and underwent a comprehensive presurgical evaluation including long-term EEG monitoring. Twenty of the 24 patients had interictal epileptiform activity (IEA) identified on the preoperative sleep and awake EEG recordings. The presence of IEA 1 year after surgery was associated with recurrent seizure activity (p < 0.05). The postoperative EEG recordings, however, revealed no IEA in the two patients with persistent seizures who had no epileptiform abnormality on the preoperative study. The extent of cortical resection appeared to have no significant effect on the recording of IEA after surgery. One-year postoperative EEG recordings are prognostically useful in patients with extratemporal lesional epilepsy who undergo surgical treatment.     

Long term outcomes in patients with preoperative generalized interictal epileptiform abnormalities following amygdalohippocampectomy

We evaluated long term surgical outcomes in 21 patients with temporal lobe epilepsy and presurgical generalized interictal epileptiform discharges (IEDs). Following amygdalohippocampectomy, 12 patients (57.1%) were noted to have favorable outcomes (Engel classification of I-II). Favorable outcomes were significantly associated with a history of auras prior to seizure onset (p=0.021), the absence of generalized IEDs on postoperative EEG (p=0.024), and the presence of focal slowing on postoperative EEG (p=0.045).     

Ganglioglioma and Intractable Epilepsy: Clinical and Neurophysiologic Features and Predictors of Outcome After Surgery

Summary: Purpose: To review the clinical, neurophysiologic, and radiological data of patients with ganglioglioma who had undergone evaluation and surgery in our Epilepsy Program.
Methods: The medical and neurophysiologic records of 38 patients with intractable epilepsy and ganglioglioma were re- viewed. Data underwent statistical analysis.
Results: There were 28 temporal and 10 extratemporal resections, with a mean age at seizure onset of 10.5 years and mean age at surgery of 22 years. Five tumor resections performed earlier were recorded. Twenty-nine patients had auras and 20 had secondarily generalized seizures. All 28 patients with temporal tumor had complex partial seizures. Preoperative MRI demonstrated the tumor in 36 of 36 patients: 17 of 29 demonstrated gadolinium enhancement, and 17 of 36 had mass effect. Scalp interictal sharp waves were present in 32 patients, and in 15 they were multiregional. In two patients, scalp EEG seizure onset was from the hemisphere contralateral to the tumor. Postoperatively, 79% of patients (30 of 38) were seizure-free (Engel's class I) at 6 months, 72% at 1 year (26 of 36), and 63% at 2 years (20 of 32). Excellent outcome was associated with a lower age at operation (p = 0.008), shorter duration of epilepsy (p = <0.01), absence of generalized seizures (p = <0.01), and no epileptiform discharges on a postoperative EEG (p = 0.01).
Conclusions: Good surgical outcome is expected in patients with ganglioglioma despite years of medically resistant seizures. Good outcome may be achieved despite EEG findings that may conflict with tumor location, and is more likely when surgery is performed relatively soon after epilepsy onset.     

Postoperative EEG and seizure outcome in temporal lobe epilepsy surgery.

OBJECTIVE: To assess the prognostic value of scalp electroencephalogram (EEG) after epilepsy surgery, we investigated whether postoperative EEG abnormalities (interictal epileptiform discharges, IED; interictal slow activity, ISA) were associated with seizure outcome and other patient characteristics after resective surgery in patients with temporal lobe epilepsy (TLE). METHODS: Sixty-two patients with medically refractory TLE who underwent surgery were studied. Patients were categorized according to etiology (mesiotemporal sclerosis vs. tumors/cortical dysplasias); extent of surgical resection (extensive vs. limited); and amount of preoperative IED on wake EEG (oligospikers, <1 IED/h, vs. spikers). Patients were also classified as seizure-free (SF) or having persistent seizures/auras (not-SF) during follow up visits 1 month and 1 year after surgery. Preoperative 60-min interictal EEGs were evaluated for IED and ISA, and compared to postoperative wake EEGs. RESULTS: Seizures/auras persisted in 16/62 (25.8%) patients at 1 month and in 8/62 (12.9%) at 1 year follow up. ISA was not significantly related to outcome. Of 42 patients with EEG negative for IED at 1 month, 4 were not-SF; at 1 year, one of 44 such patients was not-SF. IED was significantly associated with seizure/aura persistence in patients categorized as mesiotemporal sclerosis and with extensive surgery. Oligospikers and spikers on preoperative EEG showed no differences in the postoperative seizure outcome, excellent in both cases; moreover, the presence of postoperative IEDs indicated auras/seizures persistence apart from the preoperative EEG spike frequency. CONCLUSIONS: Our study showed that the presence of IED of postoperatve EEG strongly indicates seizure/aura persistence. Therefore, serial EEGs should be included in postoperative follow up schedules as a crucial tool in evaluating seizure outcome.     

Electroencephalographic findings in children with cerebral palsy: a study of 151 patients

EEG abnormalities were studied in 151 patients (79 boys, 72 girls age range 0.4-13 years) with cerebral palsy (CP). They all had standardised EEG recordings, which were read by the same electroencephalographer. Eighty-one children had seizures and 70 were seizure-free. The EEG abnormalities in the seizure group included slow waves in 36 patients (generalised asynchronous in 33 and generalised synchronous in 3); amplitude abnormalities in 2 (focal in 1, generalised 1); epileptiform activity (including isolated sharp waves, isolated spikes, and spike-wave and polyspike-wave complexes) was seen in 66 (focal in 12; generalised in 48 and multifocal in 6). Hypsarrythmia was found in 4 and burst suppression in 1. Only 6 recordings were normal giving an overall percentage of abnormality of 92.6%. Of the CP patients without seizures, 28 (40%) showed generalised asynchronous slow waves; epileptiform activity was found in 27 (focal in 2, generalised in 23 and multifocal in 2); 3 subjects showed hypsarrythmia and 24 recordings were normal. The overall percentage of abnormality in this group was 76%. Cerebral palsy in children, regardless of its cause may be associated with generalised focal EEG abnormalities. This may reflect heterogeneity of the neural-generator in the underlying disease process.     

Left dominance of EEG abnormalities in patients with transient global amnesia

PurposeTransient global amnesia (TGA) is a syndrome of unknown etiology. Electroencephalographic (EEG) abnormalities in TGA have been reported previously. We analyzed the frequency and characteristics of EEG abnormalities in patients with TGA.MethodsWe collected EEGs of patients with a clinical diagnosis of TGA who had visited the emergency room or the outpatient clinic over a period of 8 years and compared clinical and demographic characteristics of the patients with normal EEGs with those with abnormal EEGs.ResultsEEG abnormalities were found in 35 (22.9%) out of 153 patients and epileptiform discharges were seen in 26 (74.3%) out of these 35 patients. Spikes or sharp waves were detected on the left side only (48.6%) or on both sides (25.7%), but none of the patients showed spikes or sharp waves on right side only. In six patients the EEG had normalized within three months of presentation, in ten within six months, and in twelve by one year. The EEG remained abnormal in eleven out of the 23 patients one year after presentation.ConclusionIn this largest consecutive EEG study at one center, the proportion of patients with TGA in whom epileptiform discharges were demonstrated within days of the episode of TGA was significantly higher than in the previous literature. EEG abnormalities such as spikes or sharp waves spontaneously disappeared in almost half of cases over one-year of follow-up. There was a clear left dominance of EEG abnormalities in patients with TGA.     

Temporal intermittent rhythmic delta activity in electroencephalograms.

Temporal intermittent rhythmic delta activity (TIRDA) has been reported to be highly specific for diagnosing complex partial epilepsy. Of 12,198 electroencephalographic (EEG) recordings performed at the Mayo Clinic between May 1, 1990 and May 1, 1991, 33 records from 27 patients (18 women and nine men; mean age, 41.5 years; range, 13-82 years) showed TIRDA. Clinical seizures were diagnosed in all patients, and complex partial epilepsy was well documented in 23. In a control group of 100 patients without TIRDA and matched for age and sex, generalized seizures were diagnosed in 25 and partial seizures in 15. Differences between TIRDA and control groups were highly statistically significant. Focal temporal sharp waves or spikes occurred in 23 patients with EEG recordings that contained TIRDA; three of these patients also exhibited generalized atypical spike-and-wave discharges. Four patients had TIRDA but no other epileptiform activity, although earlier EEGs of three of these patients contained spikes or sharp waves. These findings confirm earlier work, and we conclude that TIRDA represents an important epileptogenic abnormality.     

Continuous electrocorticogram epileptiform discharges due to brain gliosis.

Cortical dysplasia is known to produce continuous epileptiform discharges (CEDs) on electrocorticogram (EcoG) and EEG recordings. The authors studied the incidence of CEDs on ECoGs and correlated this data with pathologic findings. Thirty ECoGs were reviewed that were performed on patients with parietal or occipital lobe epilepsy operated on since 1960. CED was classified as: (1) continuous or semicontinuous rhythmic spikes or sharp waves at frequencies ranging from 2 to 8 Hz, and (2) repetitive bursts of rhythmic polyspike activity lasting 2 to 10 s. All nontumoral pathologic specimens were reviewed. Epileptiform activity was classified using the following criteria: focal (one gyrus), regional (two gyri), lobar (three gyri), bilobar, or multilobar. Pathologic examination showed gliosis in eight specimens, focal cortical dysplasia in five specimens, tumoral lesions in eight specimens, and other pathology in nine specimens. CED was found in 11 ECoGs. In seven pathology specimens, significant gliosis was shown, and in the remaining four specimens, a dysplastic lesion was diagnosed. Epileptiform activity was widespread (lobar, bilobar, or multilobar) when gliosis or focal cortical dysplasia was present. Absence of epileptiform activity or a focal/regional distribution was found in tumors and other lesions. These data suggest that extensive gliotic lesions are highly epileptogenic and produce CEDs, which are morphologically undistinguishable from those produced by focal cortical dysplasia.     

Focal epileptiform spikes in conjuction with K-complexes.

Dyshormia or epileptiform spikes occurring within K-complexes have been described in patients with generalized epilepsy, with one study reporting that generalized spikes occurred frequently in association with K-complexes. We report the rate of focal epileptiform spikes occurring within K-complexes in localization-related epilepsy. Presurgical or diagnostic long-term video-EEG results of 40 consecutive patients with epilepsy (13 patients with right temporal lobe epilepsy, 20 patients with left temporal lobe epilepsy, and 7 patients with frontal lobe epilepsy) were reviewed. Sleep samples were reviewed and the numbers of K-complexes, spikes, and spikes within K-complexes were recorded. The comparison group consisted of 40 consecutive patients with nonepileptic events who were monitored with long-term video EEG. Focal epileptiform spikes occurring within K-complexes occurred in 2 of 13 (15%) patients with right temporal lobe patients, 6 of 20 (30%) patients with left temporal lobe, and 3 of 7 (42%) patients with extratemporal lobe epilepsy. In most patients, spikes occurring during K-complexes were rare. We identified spikes occurring during K-complexes in patients with localization-related epilepsy. The sharply contoured components of K-complexes or associated sleep spindles may obscure focal spikes within K-complexes. Nevertheless, K-complexes may be associated with focal epileptiform discharges.     

EEG and evoked potential recording from the subthalamic nucleus for deep brain stimulation of intractable epilepsy.

OBJECTIVES: The substantia nigra in the animal model has been implicated in the control of epilepsy. The substantia nigra pars reticulata (SNpr) receives afferents from the subthalamic nucleus (STN), which thus may have an effect on the control of epilepsy. There is evidence in the animal model of a direct connection from the cortex to the STN. High-frequency STN stimulation is being used in experimental trial for the management of intractable epilepsy. Our primary objective in this study was to determine if there was epileptiform activity recorded from the STN in association with scalp recorded epileptiform activity to support the presence of a pathway from the cortex to the STN in humans as described in animals that may be important for the management of epilepsy. This article describes the interictal and ictal electroencephalographic (EEG) findings as well as evoked potential recordings from the STN in these patients with intractable epilepsy. METHODS: Four patients (3 males) ranging from 19 to 45 years with intractable focal epilepsy refractory to anti-epileptic drugs were studied. Two patients failed vagal nerve stimulation and one patient had previous epilepsy surgery. Depth electrodes were implanted stereotactically in the STN bilaterally. A comparative analysis of the interictal and ictal activities recorded from the scalp and STN electrodes was performed. Median nerve somatosensory evoked potentials (SEPs) and auditory evoked potentials (AEPs) were also recorded. RESULTS: Interictal sharp waves recorded in the scalp EEG were always negative in polarity. These sharp waves were always associated with sharp waves recorded at the ipsilateral STN electrode contacts that were always positive in polarity. In addition repetitive spikes were recorded independently at the left or right STN electrode contacts, with no reflection at the scalp. These spikes were extremely stereotyped, of high amplitude and short duration, and were positive or negative in polarity. Focal scalp EEG seizures were also recorded at the ipsilateral STN electrodes. In 3 patients SEPs were recorded from the contralateral STN electrodes corresponding to the P14/N18 far-field complex. In two patients AEPs were recorded, and wave V (near-field) and wave VII (far-field) from the contralateral STN electrodes. CONCLUSIONS: This study demonstrates that scalp recorded epileptiform activity is reflected at the ipsilateral STN either following or preceding the scalp sharp waves. The STN sharp waves are most probably an expression of the direct cortico-STN glutamatergic pathways that have been demonstrated previously in animals. This pathway in man may be important with regard to a possible mechanism for the treatment of epilepsy with STN stimulation.     

Application of magnetoencephalography in epilepsy patients with widespread spike or slow-wave activity

PURPOSE: To examine whether magnetoencephalography (MEG) can be used to determine patterns of brain activity underlying widespread paroxysms of epilepsy patients, thereby extending the applicability of MEG to a larger population of epilepsy patients. METHODS: We studied two children with symptomatic localization-related epilepsy. Case 1 had widespread spikes in EEG with an operation scar from a resection of a brain tumor; Case 2 had hemispheric slow-wave activity in EEG with sensory auras. MEG was collected with a 204-channel helmet-shaped sensor array. Dynamic statistical parametric maps (dSPMs) were constructed to estimate the cortical distribution of interictal discharges for these patients. Equivalent current dipoles (ECDs) also were calculated for comparison with the results of dSPM. RESULTS: In case 1 with widespread spikes, dSPM presented the major activity at the vicinity of the operation scar in the left frontal lobe at the peak of the spikes, and some activities were detected in the left temporal lobe just before the peak in some spikes. In case 2 with hemispheric slow waves, the most active area was located in the left parietal lobe, and additional activity was seen at the ipsilateral temporal and frontal lobes in dSPM. The source estimates correlated well with the ictal manifestation and interictal single-photon emission computed tomography (SPECT) findings for this patient. In comparison with the results of ECDs, ECDs could not express a prior activity at the left temporal lobe in case 1 and did not model well the MEG data in case 2. CONCLUSIONS: We suggest that by means of dSPM, MEG is useful for presurgical evaluation of patients, not only with localized epileptiform activity, but also with widespread spikes or slow waves, because it requires no selections of channels and no time-point selection.     

Interictal Epileptiform Discharges in Temporal Lobe Epilepsy Due to Hippocampal Sclerosis Versus Medial Temporal Lobe Tumors

PURPOSE: It remains controversial whether a specific pattern of interictal epileptiform activity exists that may help to differentiate temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS) from other forms of TLE. In this study, we characterized the distribution of interictal epileptiform discharges in TLE due to HS as compared with those in patients with tumors restricted to the medial temporal lobe structures. METHODS: The study included 21 adult patients with unilateral HS who remained seizure free (>1 year) after anterior temporal lobectomy with amygdalohippocampectomy. Patients with "dual pathology" were excluded. The comparison group consisted of nine patients with tumors restricted to the amygdala and hippocampus. All patients underwent video-EEG monitoring preoperatively by using 39 scalp electrodes (including the 10-10 system over both temporal regions) and bilateral sphenoidal electrodes. RESULTS: The HS patient group showed a significantly higher percentage of ipsilateral epileptiform discharges maximal at anterior temporal electrodes (median, 97.0%; sphenoidal electrode alone, 88.1%), as compared with the tumor group (median, 72.1%; p<0.001; sphenoidal electrode alone, 24.8%; p<0.001). The HS group had significantly fewer extratemporal spikes/sharp waves (median, 0.0), as compared with the tumor group (10.0%; p<0.001). At least 90% of the interictal discharges were located in the anterior temporal region in 20 (95.2%) of 21 HS patients, but in none of the tumor patients (p<0.001). Bilateral temporal discharges were found in nine (42.9%) of 21 patients with HS and in two (22.2%) of nine tumor patients (p = 0.42). CONCLUSIONS: We conclude that ipsilateral interictal epileptiform discharges outside the anterior temporal region are rare (<10%) in adults with intractable TLE due to unilateral HS. Frequent posterior or extratemporal sharp waves may detract from the certainty of this diagnosis in complicated cases. These restricted epileptiform discharges suggest a smaller irritative zone in HS as compared with medial tumors, or a more organized activity associated with intrinsic hippocampal disease. Bilateral epileptiform discharges were not uncommon in both groups.     

Long-Term Follow-Up of Stereotactic Lesionectomy in Partial Epilepsy: Predictive Factors and Electroencephalographic Results

We performed an extended follow-up study assessing the efficacy of stereotactic lesionectomy in 23 patients with foreign-tissue lesions and intractable partial epilepsy. Sixteen lesions involved functional or eloquent cortex as determined by anatomic localization. By definition, the surgical objective in these patients was excision of the lesion, and not the surrounding cerebral cortex. The mean duration of follow-up was 48.5 months (range 26-69 months). Seventeen patients (74%) had a significant reduction in seizures (greater than or equal to 90%) after lesionectomy. Thirteen patients (56%) had a class I operative outcome (seizure-free, single seizure episode, or auras only). Five of these patients were successfully discontinued from antiepileptic drug (AED) therapy. Patients with temporal lobe lesions were statistically less likely to be rendered seizure-free (p less than 0.05). Age at operation, duration of epilepsy, and underlying pathology were not significant predictors of seizure outcome. The anatomic distribution of extracranial EEG recorded epileptiform activity did not appear to be an important determinant of outcome. The absence of interictal epileptiform activity in the 3-month postoperative EEG correlated with a significant reduction in seizures. Long-term follow-up indicates that lesionectomy may be effective in select patients with medically refractory partial seizure disorders.     

Spikes on the postoperative EEG are related to preoperative spike frequency and postoperative seizures

PURPOSE: To investigate the factors which influence the persistence of interictal epileptiform discharges (IED) after epilepsy surgery. METHODS: In this retrospective study we included patients with intractable medial temporal lobe epilepsy (MTLE) who underwent presurgical evaluation including high-resolution MRI and video-EEG monitoring with seizure registration prior to an anterior temporal lobe resection. The postsurgical outcome was assessed by our team 6 months and 2 years after the surgery. RESULTS: One hundred and forty-seven patients fulfilled the inclusion criteria. The mean age of the patients was 31.8 (range 16-59 years). In 22 patients (15%) interictal epileptiform discharges were present on the postoperative routine EEG. We found that both the preoperative spike frequency ( P < 0.001 ) and postoperative seizures ( P = 0.04 ) were independently associated with the presence of IED on the postoperative routine EEG. The preoperative spike frequency was not associated with the postoperative outcome. The extent of resection showed no influence on the presence of postoperative IED. CONCLUSION: We hypothesize that two factors independently influence the presence of postoperative spikes: chronic interictal disturbance (represented as preoperative spike frequency) and the acute (postoperative) seizures. Our study confirmed that persistent postoperative IED had a prognostic value regarding the outcome of the epilepsy surgery.     

Auras in temporal lobe epilepsy with hippocampal sclerosis: relation to seizure focus laterality and post surgical outcome

We examined the relationship between presence and frequency of different types of auras and side of lesion and post surgical outcomes in 205 patients with medically intractable mesial temporal lobe epilepsy (MTLE) with unilateral hippocampal sclerosis (HS). With respect to the number of auras, multiple auras were not associated with side of lesion (p=0.551). The side of HS was not associated with the type of auras reported. One hundred fifty-seven patients were operated. The occurrence of multiple auras was not associated with post-surgical outcome (p=0.740). The presence of extratemporal auras was significantly higher in patients with poor outcome. In conclusion, this study suggests that the presence of extratemporal auras in patients with MTLE-HS possibly reflects extratemporal epileptogenicity in these patients, who otherwise showed features suggestive of TLE. Therefore, TLE-HS patients undergoing pre-surgical evaluation and presenting clinical symptoms suggestive of extratemporal involvement should be more extensively evaluated to avoid incomplete resection of the epileptogenic zone.     

Benefit of simultaneous recording of EEG and MEG in dipole localization

PURPOSE: In this study, we tried to show that EEG and magnetoencephalography (MEG) are clinically complementary to each other and that a combination of both technologies is useful for the precise diagnosis of epileptic focus. METHODS: We recorded EEGs and MEGs simultaneously and analyzed dipoles in seven patients with intractable localization-related epilepsy. MEG dipoles were analyzed by using a BTI Magnes 148-channel magnetometer. EEG dipoles were analyzed by using a realistically shaped four-layered head model (scalp-skull-fluid-brain) built from 2.0-mm slice magnetic resonance imaging (MRI) images. RESULTS: (a) In two of seven patients, MEG could not detect any epileptiform discharges, whereas EEG showed clear spikes. However, dipoles estimated from the MEG data corresponding to the early phase of EEG spikes clustered at a location close to that of the EEG-detected dipole. (b) In two of seven patients, EEG showed only intermittent high-voltage slow waves (HVSs) without definite spikes. However, MEG showed clear epileptiform discharges preceding these EEG-detected HVSs. Dipoles estimated for these EEG-detected HVSs were located at a location close to that of the MEG-detected dipoles. (c) Based on the agreement of the results of these two techniques, surgical resection was performed in one patient with good results. CONCLUSIONS: Dipole modeling of epileptiform activity by MEG and EEG sometimes provides information not obtainable with either modality used alone.     

Extent of neocortical resection and surgical outcome of epilepsy: Intracranial EEG analysis

Purpose: Intracranial electroencephalography (EEG) monitoring is an important process in the presurgical evaluation for epilepsy surgery. The objective of this study was to identify the ideal resection margin in neocortical epilepsy guided by subdural electrodes. For this purpose, we investigated the relationship between the extent of resection guided by subdural electrodes and the outcome of epilepsy surgery. Methods: Intracranial EEG studies were analyzed in 177 consecutive patients who had undergone resective epilepsy surgery. We reviewed various intracranial EEG findings and resection extent. We analyzed the relationships between the surgical outcomes and intracranial EEG factors: the frequency, morphology, and distribution of ictal‐onset discharges, the propagation speed, and the time lag between clinical and intracranial ictal onset. We also investigated whether the extent of resection, including the area showing ictal rhythm and various interictal abnormalities—such as frequent interictal spikes, pathologic delta waves, and paroxysmal fast activity—influenced the surgical outcome. Results: Seventy‐five patients (42%) were seizure free. A seizure‐free outcome was significantly associated with a resection that included the area showing ictal spreading rhythm during the first 3 s or included all the electrodes showing pathologic delta waves or frequent interictal spikes. However, subgroup analysis revealed that the extent of resection did not affect the surgical outcome in lateral temporal lobe epilepsy. Conclusions: The extent of resection is closely associated with surgical outcome, especially in extratemporal lobe epilepsy. Resection that includes the area with total pathologic delta waves and frequent interictal spikes predicts a good surgical outcome.     

Bradycardia from flash stimulation

This case study documents a patient who experienced bradycardia brought on by flash stimulation during a routine outpatient EEG recording. The patient had known photosensitive seizures in the past. During this routine EEG, the patient's heart rate dropped to about 12 beats per minute with the EEG displaying slow‐delta‐frequency waves with no epileptiform spikes or sharp waves. During immediate follow‐up, in our emergency department, the patient had a brief asystolic event, followed by bradycardia. Cardiology examinations were normal. We propose that this response was a photic‐triggered reflex vasovagal reaction.     

Electroencephalographic studies in children with autism spectrum disorders

An important factor in the diagnosis and treatment of Autism spectrum disorder (ASD) is prescribed Electroencephalography (EEG). EEG changes may show the following: slowing, asymmetry, sharp waves or spikes, sharp and slow waves, generalized sharp and slow waves, or generalized polyspikes in a distributed or general area, multifocal or focal, unilateral or bilateral, and they may be located in many different areas of the brain. There is a need to look for a EEG phenotype typical of patients with ASD. The importance of gamma waves, rhythm mu, mirror neurons, and their role in patients with ASD was discussed. Epilepsy is reported to occur in one third of ASD patients. In ASD, seizures and EEG paroxysmal abnormalities could represent an epiphenomenon of a cerebral dysfunction independent of apparent lesions. This article reviews ASD and EEG abnormalities and discusses the interaction between epileptiform abnormalities and cognitive dysfunction.     

Comparison of electroencephalographic dipoles of interictal spikes from prolonged scalp video-electroencephalography and magnetoencephalographic dipoles from short-term recording in children with extratemporal lobe epilepsy

We retrospectively compared electroencephalographic (EEG) dipoles of interictal spikes from prolonged video-EEG monitoring with magnetoencephalographic dipoles from short-term recording in four children with extratemporal lobe epilepsy. We analyzed both sets of dipoles using individual interictal spikes and single moving dipole modeling and evaluated the profiles of spike appearance, dipole position, and orientation in EEG and magnetoencephalography. We obtained more than 100 magnetoencephalographic spikes in two patients who manifested frequent interictal EEG spikes throughout both day and night but fewer than 40 magnetoencephalographic spikes in two patients who had interictal EEG spikes mainly during sleep. The dipole positions of EEG and magnetoencephalography were in close proximity and included in the surgical resection area. Most of the dipoles between EEG and magnetoencephalography were oriented perpendicularly. A combination of EEG dipole analysis from prolonged video-EEG monitoring and magnetoencephalographic dipole analysis provides complementary information for presurgical evaluation in children with intractable extratemporal lobe epilepsy.