Focal Spikes Research Articles

Cortical Location of Benign Paroxysmal Rhythms in the Electrocorticogram

Six/second spike waves, 14 and 6/second positive spikes and small sharp spikes are apiculate paroxysmal rhythms in the electroencephalogram, thought to be of no diagnostic importance. The cortical origin of these discharges is documented in this report. These waveforms were assessed in recordings from the surface of the cerebral cortex using implanted subdural electrodes in 61 patients monitored for possible epilepsy surgery. Eight patients had 6/second spike wave, four had 14 and 6/second positive spikes and 3 had small sharp spikes. The 6/second spike waves were localised to the posterior cingulate gyrus, a more restricted region than would be predicted from scalp recordings and the 14 and 6/second spikes to the posterior mesial temporal cortex. Small sharp spikes were more widely distributed but also predominated in the posterior mesial temporal area. None of the discharges were congruent with the focus of seizure origin and no interaction with other interictal spikes was found. These benign paroxysmal rhythms can appear incidentally in the electrocorticograms of patients with focal epilepsy and should not be confused with focal pathological spike activity or considered to be of any value in localizing the seizure focus.

Detection and significance of focal, interictal, slow-wave activity visualized by magnetoencephalography for localization of a primary epileptogenic region.

Magnetoencephalography (MEG) is a novel noninvasive diagnostic tool used to determine preoperatively the location of the epileptogenic zone in patients with epilepsy. The presence of focal slowing of activity recorded by electroencephalography (EEG) is an additional indicator of an underlying pathological condition in cases of intractable mesial temporal lobe epilepsy (MTLE). In the present study the authors examined the significance of focal, slow-wave and interictal spike activity detected using MEG in 29 patients who suffered from MTLE that was not associated with structural brain lesions. All patients underwent resective surgery after MEG and EEG monitoring. Equivalent single-dipole modeling was applied to focal low-frequency magnetic activity (LFMA) and interictal paroxysmal activity. Lateralized LFMA was defined as trains of rhythmic activity over the temporal area, with frequencies lower than 7 Hz, which were easily distinguished from background activity. Lateralized LFMA was found in 17 patients (58.6%); it always occurred on the side ipsilateral to the side of resection and displayed a maximum amplitude over the temporal area. Dipolar sources of magnetic flux computed during slow-wave trains were found in the majority of cases in the posterior superior temporal region and, occasionally, in mesial temporal structures that were subsequently resected. With respect to lateralization there was never disagreement between LFMA and MEG interictal spike sources. Thus, in patients with MTLE that is not associated with a mass lesion LFMA is topographically related to the epileptogenic area and, therefore, has value for reliable determination of the side and, possibly, the location of this area. Although focal slowing of EEG background activity is generally considered to be a nonspecific sign of functional disturbance, interictal LFMA in patients with MTLE should be conceptualized as a distinct electrographic phenomenon that is directly related to the epileptogenic abnormality. Analyzing the interictal MEG distribution of LFMA and sharp activity improves the diagnostic utility of MEG in patients with suspected TLE who are undergoing surgical evaluation.

Cerebral dysplasias: reviewed from a neurophysiological perspective.

Improvements in neuroimaging techniques have highlighted the role of cerebral dysplasia in developmental disorders and in epilepsy. The current classification is founded on the presumed timing of the first insult as deduced from the imaging appearances. Although clinical neurophysiological findings are often non-specific, several unusual patterns have been reported in association with certain types of malformation. These include the high amplitude rhythmic activities of lissencephaly, and focal rhythmic spikes. In this general review, we describe the electroence-phalographic and evoked potential findings in a wide range of cerebral dysplasias, including our personal experience of rare conditions such as Ramer-Lin syndrome. We focus on their role in assessment and on potential insights into pathophysiology.

Functional MRI of Interictal EEG Activity.

Simultaneous EEG and Functional MRI of Epileptic Activity: A Case Report Baudewig J, Bittermann HJ, Paulus W, Frahm J Clin Neurophysiol 2001;112:1196–1200 Objectives Attempts to localize the source of epileptic activity by linking electroencephalographic (EEG) abnormalities to blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) signal alterations are hampered mainly by EEG distortions during MRI, subject motion, and unknown hemodynamic response characteristics. Methods Using T2*-weighted echo-planar imaging at 2.0 T (2 s temporal resolution, 2 × 2 × 4 mm(3) spatial resolution), this work demonstrates strategies to alleviate some of these problems while studying a patient who had idiopathic generalized epilepsy with poly-spike and slow-wave complexes. Results Continuous EEG recordings during dynamic MRI (500 ms scanning, 1500 ms delay) and post-examination derivation of an EEG reference function for MRI analysis revealed positive BOLD MRI responses with temporal characteristics similar to those obtained for functional challenges. Conclusions The ability to map focal epileptic activity and/or associated cognitive processing provides new potential for both epilepsy research and clinical patient management. Spatio-Temporal Imaging of Focal Interictal Epileptiform Activity Using EEG-Triggered Functional MRI Krakow K, Lemieux L, Messina D, Scott CA, Symms MR, Duncan JS, Fish DR Epileptic Disord 2001;3:67–74 EEG-triggered, blood oxygen level-dependent functional MRI (BOLD-fMRI) was used in 24 patients with localization-related epilepsy and frequent interictal epileptiform discharges (spikes) to identify those brain areas involved in generating the spikes, and to study the evolution of the BOLD signal change over time. The location of the fMRI activation was compared with the scalp EEG spike focus and the structural MR abnormality. Twelve patients (50%) had an fMRI activation concordant with the EEG focus and structural brain abnormalities where present (n = 7). In 2 other patients, the fMRI activation was non-concordant with electroclinical findings. The remaining 10 patients (41.7%) showed no significant fMRI activation. These patients had significantly lower mean spike amplitudes compared to those with positive fMRI results (p = 0.03). The time course of the BOLD response was studied in 3 patients and this revealed a maximum signal change 1.5 to 7.5 sec after the spike. In conclusion, EEG-triggered fMRI can directly identify the generators of interictal epileptiform activity, with high spatial resolution, in selected patients with frequent spikes. The superior spatial resolution obtainable through EEG-triggered fMRI may provide an additional non-invasive tool in the presurgical evaluation of patients with intractable focal seizures.

Functional MRI of Interictal EEG Activity

ObjectivesAttempts to localize the source of epileptic activity by linking electroencephalographic (EEG) abnormalities to blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) signal alterations are hampered mainly by EEG distortions during MRI, subject motion, and unknown hemodynamic response characteristics. MethodsUsing T2*-weighted echo-planar imaging at 2.0 T (2 s temporal resolution, 2 × 2 × 4 mm(3) spatial resolution), this work demonstrates strategies to alleviate some of these problems while studying a patient who had idiopathic generalized epilepsy with poly-spike and slow-wave complexes. ResultsContinuous EEG recordings during dynamic MRI (500 ms scanning, 1500 ms delay) and post-examination derivation of an EEG reference function for MRI analysis revealed positive BOLD MRI responses with temporal characteristics similar to those obtained for functional challenges. ConclusionsThe ability to map focal epileptic activity and/or associated cognitive processing provides new potential for both epilepsy research and clinical patient management.Spatio-Temporal Imaging of Focal Interictal Epileptiform Activity Using EEG-Triggered Functional MRIKrakow K, Lemieux L, Messina D, Scott CA, Symms MR, Duncan JS, Fish DREpileptic Disord 2001;3:67–74EEG-triggered, blood oxygen level-dependent functional MRI (BOLD-fMRI) was used in 24 patients with localization-related epilepsy and frequent interictal epileptiform discharges (spikes) to identify those brain areas involved in generating the spikes, and to study the evolution of the BOLD signal change over time. The location of the fMRI activation was compared with the scalp EEG spike focus and the structural MR abnormality. Twelve patients (50%) had an fMRI activation concordant with the EEG focus and structural brain abnormalities where present (n = 7). In 2 other patients, the fMRI activation was non-concordant with electroclinical findings. The remaining 10 patients (41.7%) showed no significant fMRI activation. These patients had significantly lower mean spike amplitudes compared to those with positive fMRI results (p = 0.03). The time course of the BOLD response was studied in 3 patients and this revealed a maximum signal change 1.5 to 7.5 sec after the spike. In conclusion, EEG-triggered fMRI can directly identify the generators of interictal epileptiform activity, with high spatial resolution, in selected patients with frequent spikes. The superior spatial resolution obtainable through EEG-triggered fMRI may provide an additional non-invasive tool in the presurgical evaluation of patients with intractable focal seizures.

Atypical "benign" partial epilepsy or pseudo-Lennox syndrome. Part I: symptomatology and long-term prognosis.

Atypical benign partial epilepsy (ABPE) or pseudo-Lennox syndrome (PLS) is characterised by generalised minor seizures and focal sharp slow waves and spikes (SHW) as observed in Rolandic epilepsy (RE), but with exceptional pronounced activation during sleep. The aim of this study was to describe the full spectrum of ABPE in the hitherto largest group of patients. We retrospectively analysed the clinical and EEG data of 43 children who fulfilled the following criteria: occurrence of generalised minor seizures as described for ABPE (i.e., atonicastatic seizures, myoclonic seizures, atypical absences) and focal SHW identical to those observed in RE, but with generalisation during sleep. Language development prior to onset of epilepsy was retarded in 26% of patients. In 74%, age at onset of epilepsy ranged from 2 to 6 years. Manifestation occurred earlier in boys than in girls. Generalised minor seizures constituted the predominating seizure type in 67% of patients. Twenty-eight percent of patients suffered from simple partial seizures of the oro-facial region or generalised tonic-clonic seizures originating from the oro-facial region. Additionally, generalised tonic-clonic (44%), unilateral (21%), partial motor (44%), versive (12%), focal atonic (9%), and complex-partial seizures (2%) were observed. A bioelectrical status was recorded in 56% of patients during sleep. No tonic seizures and no fast spike series (bursts of 10-20 Hz rhythms) were observed. At last follow-up, 84% of patients were in clinical remission. All subjects older than age 15 were seizure-free. However, 56% of patients attended a school for mentally handicapped children. ABPE or PLS broadly overlaps with RE, electrical status epilepticus during sleep, and Landau-Kleffner syndrome. Regarding the epilepsy, the prognosis is excellent, mental deficit, however, seems to be frequent. The differentiation from Lennox-Gastaut syndrome and myoclonic astatic epilepsy is essential. Instead of ABPE, the term pseudo-Lennox syndrome is proposed.

Spatial learning deficits without hippocampal neuronal loss in a model of early-onset epilepsy

Studies were undertaken to examine the effects recurrent early-life seizures have on the ability of rats to acquire spatial memories in adulthood. A minute quantity of tetanus toxin was injected unilaterally into the hippocampus on postnatal day 10. Within 48 h, rats developed recurrent seizures that persisted for 1 week. Between postnatal days 57 and 61, rats were trained in a Morris water maze. Toxin-injected rats were markedly deficient in learning this task. While these rats showed gradual improvement in escape latencies over 20 trials, their performance always lagged behind that of controls. Poor performance could not be explained by motor impairments or motivational difficulties since swimming speed was similar for the groups. Only eight of 16 toxin-injected animals showed focal interictal spikes in the hippocampus during electroencephalographic recordings. This suggests that learning deficiencies and chronic epilepsy may be independent products of recurrent early-life seizures. A quantitative analysis of hippocampus revealed a significant decrease in neuronal density in stratum pyramidale of experimental rats. However, the differences were largely explained by a concomitant increase in the area of stratum pyramidale. Studies of glial fibrillary acidic protein expression and spread of horseradish peroxidase-conjugated tetanus toxin in the hippocampus suggest that the dispersion of cell bodies in stratum pyramidale can neither be explained by a reactive gliosis nor the direct action of the toxin itself. Taken together, we suggest that recurrent seizures beginning in early life can lead to a significant deficiency in spatial learning without ongoing hippocampal synchronized network discharging or a substantial loss of hippocampal pyramidal cells.

Results of surgery in patients with refractory extratemporal epilepsy with normal or nonlocalizing magnetic resonance findings investigated with subdural grids.

To study the efficacy of extensive coverage of the brain surface with subdural grids in defining extratemporal cortical areas amenable for resection in patients with refractory extratemporal epilepy (R-ExTE) and normal or nonlocalizing magnetic resonance imaging (MRI) scans. Sixteen patients with R-ExTE were studied. Eleven patients had simple partial, eight had complex partial, and three had supplementary motor area seizures. Seizure frequency ranged from three per month to daily episodes. Interictal EEG showed large focal spiking areas in 11 patients, secondary bilateral synchrony in four, and was normal in one patient. Surface ictal recordings were nonlocalizing in six patients, and in 10, they disclosed large ictal focal spiking areas. MRI was normal in 10 patients, and in six patients, focal nonlocalizing potentially epileptogenic lesions were found. All patients were given an extensive coverage of the cortical convexity with subdural electrodes through large unilateral (n = 13) or bilateral (n = 3) craniotomies. Bipolar cortical stimulation was carried out through the implanted electrodes. Interictal invasive recording findings showed widespread spiking areas in 13 patients and secondary bilateral synchrony in three. Ictal invasive recordings showed focal seizure onset in all patients. There were six frontal, two parietal, one temporooccipital, four rolandic, and three posterior quadrant resections. Thirteen patients had been rendered seizure free after surgery, and three had > or =90% of seizure-frequency reduction. Pathologic findings included gliosis (n = 10), cortical dysplasia (n = 5), or no abnormalities (n = 1). Six patients had transient postoperative neurologic morbidity. Extensive subdural electrodes coverage seems to be an effective way to investigate patients with R-ExTE and normal or nonlocalizing MRI findings.

Spatio‐temporal imaging of focal interictal epileptiform activity using EEG‐triggered functional MRI

ABSTRACT EEG‐triggered, blood oxygen level‐dependent functional MRI (BOLD‐fMRI) was used in 24 patients with localization‐related epilepsy and frequent interictal epileptiform discharges (spikes) to identify those brain areas involved in generating the spikes, and to study the evolution of the BOLD signal change over time. The location of the fMRI activation was compared with the scalp EEG spike focus and the structural MR abnormality. Twelve patients (50%) had an fMRI activation concordant with the EEG focus and structural brain abnormalities where present ( n = 7). In 2 other patients, the fMRI activation was non‐concordant with electroclinical findings. The remaining 10 patients (41.7%) showed no significant fMRI activation. These patients had significantly lower mean spike amplitudes compared to those with positive fMRI results (p = 0.03). The time course of the BOLD response was studied in 3 patients and this revealed a maximum signal change 1.5 to 7.5 sec after the spike. In conclusion, EEG‐triggered fMRI can directly identify the generators of interictal epileptiform activity, with high spatial resolution, in selected patients with frequent spikes. The superior spatial resolution obtainable through EEG‐triggered fMRI may provide an additional non‐invasive tool in the presurgical evaluation of patients with intractable focal seizures.

Current trends in electroencephalography.

Several recent articles re-emphasize the value of clinical electrophysiology: in localizing epileptogenesis, predicting effectiveness of epilepsy surgery, and disclosing a mechanism of benign Rolandic epilepsy of childhood.A review of the role of EEG in the diagnosis of epilepsy indicated that epileptiform activity will appear in 50% of initial awake recordings of adults with epilepsy and in 85% of subjects undergoing two recordings. This contrasts with the appearance of spikes in only 4 of 1000 normal persons. Several studies focused on the value of electroencephalography in extratemporal epilepsy: 62% of patients with neocortical epilepsy had at least one localizing ictal EEG; occipital and temporal neocortical seizures were localized in a greater proportion than frontal or parietal attacks. Interictal spikes, if unifocal, always arose from the epileptogenic region in a study of their seizure localizing value. Such congruence augured for better seizure control by focal resection in two studies reviewed herein. Studies indicating the value of interictal temporal lobe spikes and scalp-recorded seizures in lateralising a temporal seizure focus are reviewed. One study found EEG to be slightly more reliable for lateralization of temporal epileptogenesis than MRI. In patients with benign Rolandic seizures, enhanced motor evoked potentials (MEPs) were obtained from transcranial magnetic stimulation when this was applied 50-80 msec after electrical stimulation of the thumb whereas this interval inhibited the MEP in normal subjects. This suggests that afferent cutaneous input abnormally and synchronously activates a large population of sensory neurons; such activation is subsequently transmitted to the motor cortex to produce the focal spikes in this condition.Finally, advances in non-invasive technology have redefined and limited the need for invasive monitoring in children with intractable seizure disorders.

A study of the relationship between metabolism using1H-MRS and function using several neuropsychological tests in temporal lobe epilepsy

Several investigators have reported on the relationship between metabolism, using magnetic resonance spectroscopy (MRS), and function, using neuropsychological tests in temporal lobe epilepsy (TLE) patients , but the opinions regarding the results remain in contention. The aim of this study is to examine the relationship between metabolism, using proton MRS (1H-MRS), and function using several neuropsychological tests in the temporal lobes of TLE patients. We studied 29 TLE patients at our hospital using1H-MRS and neuropsychological tests. We used a clinical 1.5 T MR unit. We conducted five neuropsychological tests to examine the function of the left or right temporal lobe. There were significant correlations between the N-acetylaspartate/creatine + phosphocreatine (NAA/Cr) ratios and the scores of almost all of the neuropsychological tests for the temporal lobe function ipsilateral to the spike focus. However, in two Wechsler Memory Scale-Revised (WMS-R) subtests we found no significant correlation in the ipsilateral side. These findings suggest that the NAA/Cr ratios, which reflect neural metabolism, are closely related to function in the temporal lobes of TLE patients . The disparity between the results in two subtests of WMS-R show that several tests may be necessary in order to assess temporal lobe function.

Long-lasting effects of feline amygdala kindling on monoamines, seizures and sleep

This report describes the relationship between monoamines, sleep and seizures before and 1-month after amygdala kindling in young cats (<1 year old; n=8; six female and two male). Concentrations (fmoles of norepinephrine or NE, dopamine or DA and serotonin or 5-HT) were quantified in consecutive, 5-min microdialysis samples (2 μl/min infusion rate) from amygdala and locus ceruleus complex (LC) during four, 6–8-h polygraphic recordings before ( n=2) and 1 month post-kindling ( n=2); 5-min recording epochs were temporally adjusted to correspond to dialysate samples and differentiated according to dominant sleep or waking state (lasting ≥80% of 5-min epoch) and degree of spontaneous seizure activity (number and duration of focal versus generalized spikes and spike trains and behavioral seizure correlates). Post-kindling records in each cat were divided into two groups ( n=1 record each) based on higher or lower spontaneous EEG and behavioral seizure activity and compared to pre-kindling records. We found: (1) before and after kindling, NE and 5-HT but not DA concentrations were significantly lower in sleep than waking at both sites; (2) after kindling, each cat showed cyclic patterns, as follows: (a) higher NE, 5-HT and DA concentrations accompanied increased seizure activity with delayed sleep onset latency and increased sleep fragmentation (reduced sleep state percentages, number of epochs and/or epoch duration) in one recording versus (b) lower monoaminergic concentrations accompanied reduced seizure activity, rapid sleep onset and reduced sleep disruption in the other recording. The alternating, post-kindling pattern suggested ‘rebound’ effects which could explain some controversies in the literature about chronic effects of kindling on monoamines and sleep–waking state patterns.

Ictal brain hemodynamics in the epileptic focus caused by a brain tumor using functional magnetic resonance imaging (fMRI)

Using functional magnetic resonance imaging (fMRI) we were able to observe, in detail, ictal brain hemodynamics during epileptic seizure caused by a brain tumor. A 53-year-old man was experencing partial motor seizures of the left side of his face and neck. In a brain MR image a mass lesion was found in the subcortical area of the right frontal lobe. We found focal spikes in his right hemisphere, though dominantly in C4 and T4 regions. fMRI investigations were carried out at 1.5 T (GE Signa Horizon) using gradient-echo echo-planar neuroimaging. We were able to perform the ictal examination twice. The activated regions were focalized and clearly found only on the lateral side of the tumor base. The region was in agreement with the epileptic focus examined using an electrocorticogram (ECOG). The signal intensity in the seizure focus rapidly increased 30 seconds before the convulsion was observed. After the end of the convulsion it also took 30 seconds to restore the signal intensity to the baseline value. fMRI is a very useful tool for various studies such as the identification of the epileptic focus, the mechanism of epileptic seizure, and so on.

SPECT in focal enterovirus encephalitis: evidence for local cerebral vasculitis

We report a 4-year-old, left-handed male with focal coxsackievirus A3 encephalitis who presented with seizures and acquired aphasia. Electroencephalography exhibited focal spike discharges over the right frontal regions, but cranial magnetic resonance imaging did not reveal any structural abnormalities. However, brain single-photon emission computed tomography performed during the acute phase disclosed focal hypoperfusion in the right frontal lobe, consistent with decreased regional cerebral blood flow in the territory of some branches of the right cerebral anterior artery. Without specific treatment, the patient recovered completely within 1 month, when brain single-photon emission computed tomography images returned to normal and cranial magnetic resonance imaging still demonstrated no abnormalities. The present case suggests the possible role of transient local cerebral vasculitis in the pathogenesis of focal enterovirus encephalitis.

Time‐Course of Changes of SPECT, EEG, and Seizures in Temporal Lobe Epilepsy

Purpose: Rccent reports havc shown that diagnostic imaging by SPECT is uscfiil in the assessment of cpilcptogcnic foci in the brain. We investigated the relationship betwcen the time‐course of SPECT, EEG, and seizure changes over 3‐ to 6‐year periods. Changes wcre correlatcd with therapeutic effect assessments and predicted prognoses. In our study, SPECT and EEG data werc recorded on the same day.Subjects: Subjects comprised 27 outpaticnts with temporal lobe epiIcpsy, mean age and duration of disease of 39.2 years and 23.2 years, respectively. Seizure frequencies were weekly in 4 subjects, monthly in 7, yearly in 6, no seizure for I to 4 years in 6, and no seizure for 2 3 years in 4. Methods: The early phase SPECT images were taken 30 minutes after intravcnous administretion of 1231‐IMP. Resting EEG was sub‐scqucntly recorded. SPECT scanning was performed on horizontal and coronary sections. Regional cerebral blood flow findings were coin‐parcd by visual inspection. Results: In 9 of the 14 subjects whose seizure severity improved over time, focal spikes wcrc tiot observed i n either examination, or disappeared by second examination. I n contrast, only 5 of the 14 subjects had normal basic EEG activity by the second examination. SPECT usually did not improve. Only I ol the 14 subjects whose seizure scvcrity improved over time showed normalized SPECT findings. No subjects with scizure severity rating “unchanged” or “worsened” showed normalized SPECT findings. SPECT normalized i n only I of the 16 subjects i n whoin focal spikes wcrc not observed in either cxamination, or disappeared by second examination. Conclusions: In our present study, improvement of seizures with treatment or over tiinc wits likely to be correlated with improvement in focal spikes but not with SPECT findings. This agrees with the report of Michihiro et al. in that focal spike disappearance preceded SPECT finding normalization during treatment.

Dipole Tracing Examination for the Electric Source of Photoparoxysmal Response Provoked by Half‐Field Stimulation

Purpose: Dipole tracing (DT) is a computer‐aidcd noninvasive method used to estimate the location of epileptic discharges from the scalp EEG. In DT equivalent current dipoles (ECDs), which rcflcct the electric source in the brain, are rcsponsible for the potential distribution on the scalp EEC. Thercfore, the DT method is useful to estimatc the focal paroxysmal discharges. In this study we examined the location of the clectric source of photoparoxysmal response (PPR) using scalpskull‐brain dipolc tracing (SSB‐DT) after hal[‐field stimulation, which produced focal PPR on the scalp EEG. Methods: We studied 4 cases of photoscnsitive epilepsy. Wc performed 20 Hz red flicker and flickcring dot pattern half‐ficld stimulation to provoke PPR. In this method, the loci of gcnerators corresponding to the paroxysmal discharges were estimated as ECDs by I ‐ and 2‐dipole analyses. Each location of the ECDs was estimated by iterative calculation. Algorithms minimizing the squarcd difference betwccn the electrical potentials recorded from the scalp EEG and those calculated theoretically from the voluntary dipoles were uscd. In the SSB model, the scalp shell was reconstructed from the helmet mcasurements, and the shapc of the skull and brain was 3‐dimcnsionally reconstructed from CT images. A dipolarity larger than 98% w the accuracy of the estimation. We recorded thcir 2 I channel monopolar scalp EEG. Each spike was sampled analyzed at 10 points around the peaks of at least 10 spikes in each patient using the SSB‐DT method. The ECDs were then supcrimposed on thc MRI of each palient to idcntify the more cxact anatomical region. Results: This study showed the location of cach focus and a dipolarity of greater than 98% in all cases, although the results from the 2‐dipole method showed scattered location. We considered that the analyzed signals were generated from single source. PPR was elicitcd cross‐lateral to the field stimulated. By red flicker half‐field stimulation, EEG revealed eithcr focal spikes and waves in the contralatcral occipital, temporo‐occipitel region, or diffuse spikes and wave complex bursts, sccn dominantly at the contralateral hcmisphere. The supcrimposed ESDs on MRI were located at the occipital or inferior temporal lobe. PPR, provoked by flickering dot pattern half‐field stimulation, werc focal spikes and waves, mainly in the occipital, parieto‐occipital region, or diffuse spikes and wave complcx bursts, seen dominantly at thc contralateral hcmiaphere. The ECDs of their PPRs were located in the occipital, inferior temporal, or inferior pirietal lobules on MRI. Conclusion: Our findings suggest that the inferior temporal and inferior parictal lobules which are important for the processing sequence of the visual system in addition to the occipital lobc, might he responsible for thc mechanism of PPR by half‐ficld stimulation, espccially for electric source expansion.

Surgery for Catastrophic Epilepsy with Temporo‐Parieto‐ Occipital Cortical Dysplasia: Clinical Features and Surgical Outcome of Three Patients.

Purpose: Three children with temporo‐parieto‐occipital cortical dys‐ plasia manifesting refractory seizures and severe mental retardation were treated by surgical resection of the epileptogenic lesions. Their clinical features and surgical outcome are presented. Case report: Case 1 was a boy who was operated at 2 years and 9 months of age. He had had intractable partial seizures since the second postnatal day and serial spasms since 3 months old. He was admitted to our hospital at 9 months of age. Interictal electroencephalograms (EEG) showed increased slow waves in the left hemisphere and spikes and sharp waves in either both hemispheres or the left hemisphere. Rhythmic theta activities originating in the left posterior temporal and occipital areas were accompanied by partial seizures with eye blinking, respiratory change, and automatism in the extremities. Partial seizures occurred 40 to 50 times a day. Serial spasms appeared several times a day and always following partial seizures.Case 2 was a boy who was operated at 5 years and 10 months of age. He had had spasms since the third postnatal day. Partial seizures with eye blinking, eye deviation to the right, and rigidity of the extremities appeared at the age of 2 months. He was admitted to our hospital at 4 years and 9 months of age. Interictal EEGs showed hilateral diffuse spikes, and focal spikes and sharp waves in the left occipital, left frontal, and right occipital areas. Partial seizures occurred 50 to 70 times a day with rhythmic theta activities in the left occipito‐parietal area. Serial spasms occurred 2 to 7 times a day.Case 3 was a girl who was operated at 3 years and 10 months of age. Onset of upper gazing was noted at I month old and spasms 2 weeks arterwards. She was admitted to our hospital at the age of 4 months. Interictal EEGs showed spikes in the right occipital area. At the onset of a partial seizure, EEGs revealed fast rhythms at the 02 and T4 clectrodes, which was followed by eye deviation to the left or right, eye blinking, and opisthotonus of the body. Partial seizures occurred 10 to 20 timcs a day and spasms appeared at a frequency of several series per day.All cases had severe mental retardation, and Cases 1 and 2 showed hypotonia. MRI revealed abnormal gyrations and signal abnormalities in the left (Cases 1 and 2) or the right (Case 3) temporo‐parietooccipital areas. Temporo‐parieto‐occipital resection was performed on the lcft side in Cases 1 and 2, and on the right side in Case 3. Pathological findings of the resected tissues from all the patients showed abnormal cortical structures, ectopic neurons, and balloon cells. Cortical dysplasia was diagnosed.Partial seizurcs reduced in frequency by 10 % in Cases 1 and 2, and disappeared in Case 3, after surgery. Spasms disappeared before surgcry in Cases 1 and 3, and immediately after surgery in Case 2.All patients showed an improvement of neuropsychological devel‐ opment after surgery with no surgical sequel. Conclusion: Patients with temporo‐parieto‐occipital cortical dyspla‐ sia and intractable seizures may be good candidates for surgical treat‐ ment, if the epileptogenic lesion can be defined.

ESES Syndrome with Acquired Aphasia

Case Report: A 7‐year‐old boy presented with a 2‐year history of convulsions. Birth history was unremarkable. His motor and mental development were normal until the onset of partial seizures of his face at the age of 5.3 years, usually upon awakening. CBZ failed to control seizures. At 6.3 years he began to display slow speech, drooling, and reading difficulties. Absence attacks began at age 7. Upon examination, muscle weakness and cerebellar ataxia and paresis were absent. He showed sudden loss of tone in the arms when eating or writing, considered to represent negative myoclonus. Laboratory examination including CBC, blood chemistry, CSF studies, and MRI all were normal. EEG showed continuous diffuse spike and wave bursts associated with focal spikes at mid‐temporal and central area in the sleep record. Overnight sleep EEG showed continuous diffuse spike and wave bursts during slow wave sleep. The spike wave index was about 30% among slow wave sleep stages. During REM sleep, rapid eye movements disturbed the discharges of the diffuse spike and wave complex on EEG. His intelligent quotient was about 73 in the Tanaka‐Binnet test. Attention was limited and he could not copy figures accurately due to pour eye‐hand coordination. Speech therapy evaluation found word finding difficulty, paraphasia, slow speech, misuse of different consonants, distortion of vowels, and motor articulatory disturbance or motor aphasia. He lacked oral dyspraxia. During a hospital admission, ACTH‐2 was administered intramuscularly 2 I times in addition to oral administration of valproate, phenytoin, and carbamazepine. Convulsions were controlled, and he gradually recovered from the motor aphasia. Diffuse abnormalities of EEG resolved, but focal spikes remained over centro‐temporal areas during sleep. Cognitive function and vocabulary improved. Negative myoclonus of his hand disappeared. Several months after ACTH therapy, however, he suffered from moderate difficulties with word finding and the EEG deteriorated. Conclusions: ESES syndrome consists of “electrical status epilepticus during sleep”, “nonconvulsive status epilepticus with epileptic negative myoclonus”, “atypical benign partial epilepsy”, and “LandauKleffner syndrome“. According to Ohtahara, Landau‐Kleffner syndrome is characteristic of auditory agnosia. There have been no reports of motor aphasia associated with this syndrome. The present case does not meet criteria for “electrical status epilepticus during sleep” because of the low spike‐wave index but may be considered a variant of ESES. The distinctive features of this case are motor aphasia and negative myoclonus, as well as diffuse spike‐waves during slow wave sleep. Long‐term prognosis of this patient is not presently known.

VIQ‐PIQ Discrepancies in Partial Epilepsy: On the Relation to Lat‐ eralities of Focal MRI Lesions, P3 Peaks, and Focal Spikes.

Purpose: A number of previous ncurophysiological studies have indicated that the glutamatergic system is important in the induction of epileptiform activity and the dcvelopment of epileptogenesis. Clutamate transport is the primary mechanism of inactivation of syiiaptically released glutamate. GLAST is classified BS an astrocytic transporter and occurs in high concentrations in the ccrebcllum. The pathophysiologic rolc of GLAST in epilepsy is not known in detail. To investigate the role of thc astroglial glutamatc transporter GLAST in epileptogenesis, we compared amygdalu‐kindling and pentylenctetrazolc (PTZ) induced seizures in GLAST‐deficient mice (GLAST(‐/‐)) wild‐type mice (GLAST(+/+)), and maternal C57Black6/J mice (C57). Purpose: Subtest IQ such as verbal IQ (VIQ) and performance IQ (PIQ) in WAIS or WISC are thought to represent neuropsychological functions of the left and right hemispheres, respectively. The P300 (P3) event‐related potential reflects cognitive processes. We do not ye1 know the brain site of P3 origin or how epileptogenic foci (EF) influ‐ ence P3 potentials. To examine neuropsychological influence by partial epilepsy (PE), we studied VIQ‐PIQ discrepancies in PE in relation to lateralities of focal MRI lesions, P3 peaks, and EF. Methods: Thirteen patients showed VIQ‐PIQ discrepancies significant at the p7lt;O.O5 level, represented by a&gt;l2‐point spread for the WAIS in adults, and a 15‐point spread in the WISC in children. We evoked P3 potentials in the individuals with discrepant IQ differences by asking them to keep a mental count of rare tones, including introduction of oddbail tones. EEGs were recorded by the international 10–20 system and P3 peaks were shown in a topographical view by offline analysis. Patients were divided into normal and abnormal groups according to MRI findings, and were examined for the laterali‐ ties of the dominant side in subtest IQ (conventionally, we regarded higher VIQ as left hemisphere dominant and higher PIQ as right hemisphere dominant), P3 peaks, and EF. We did not correlate results with lert or right handedness. Results: Five patients (38.5%) were in the normal group and 8 patients (61.5%) were in the abnormal group. Concordance of the lateralities in P3 peaks and dominant side in subtest IQ was shown in 1 patient (20%) in the normal group and 5 patients (62.5%) in the abnormal group. In the normal group, all patients showed contralateral P3 peak shift to EF, and all except I patient showed contralateral P3 peak shift to the dominant side in subtest IQ. The other 3 patients in the abnormal group showed unilateral focal cortical dysplasias (FCD), ipsilateral P3 shift, and contralateral dominant side in subtest IQ to the focal MRI lesions. Conclusion: In our partial epilepsy series with VIQ‐PIQ discrepancies, concordance of the lateralities in P3 peaks and dominant side in subtest IQ was shown in &lt; half of the patients. Epileptogenic foci seem to have 3 different grades of influence on P3 peak shift and dominant side in subtest IQ according to the severities of accompanying focal MRI lesions: 1. Without MRI lesions, EF can make P3 peak shift contralaterally, but the dominant side in the subtest IQ shift ipsilaterally; 2. With less severe focal MRI lesions such as hippocampal atrophy etc., EF can make not only P3 peaks but also the dominant side in the subtest IQ shift contralaterally; 3. With severe focal MRI lesions such as FCD, EF can make the dominant side in the subtest IQ shift contralaterally, but the P3 peak may shift ipsilaterally. Epileptogenic foci without MRI lesions seem to control ipsilateral P3 potentials. MRI lesions render a hemisphere unlikely to become dominant, but epileptogenic foci can coexist with apparently normal neuropsychological function.

Ictal “Doppelganger” Experience.

Purpose: To believe in another sclf (“Doppelganger” experience) connotes eithcr a sensation of another self being nearby (“leibhaftige BewuBtsein” type) or autoscopy. Such experiences can occur as a component of a simple partial seizure with psychic symptomatology. Ictal autoscopies are dividcd into (1) seeing another self as if in a familiar scene in the past (scene type): and (2) seeing another self as if in a mirror (mirror type). We here summarize features of patients with the ictal “Doppelganger” experience. Method: Thirteen right‐handed people with epilepsy with the ictal “Doppelganger” experience (3 men and 10 women: mean age, 42.5 years: range, 22–57 years) were studied. Results: In any given seizure, “Doppelganger” experiences were preceded by I or more of subjective components, which, as depicted below, are listed in order of appearance and are linked by arrows: déjà vu → depersonalization 4 “Doppelganger” of “leibhaftige BewuBtsein” type (1 case), déjà vu depersonalization “Doppelganger” of “leibhaftige BewuBtsein” type → autoscopy of scene type (2 cases), déjà vu → depersonalization →“Doppelganger” of “leibhaftige Be‐ wuBtscin” type déjà autoscopy of mirror type (2 cases), déjà vu → dcpersoiialization → autoscopy of scene type (2 cases), déjà vu →“Doppelganger” of “leibhaftige BewuBtsein” type autoscopy of scene type (2 cases), déjà vu autoscopy of scene type (Icase), depersonalization 4 “Doppelganger” of “leibhaftige BewuBtsein” type (1 case), depersonalization →“Doppelganger” of “leibhaftige BewuBtsein” type → autoscopy of mirror type (Icase), elementary visual hallucination, visual illusion → autoscopy of mirror type (2cases). The interictal EEG showed temporal spike foci in 7cases with autoscopy of scene type and 2 cases with no seizure evolution further than “Doppelganger” of “leibhaftige BewuRtsein” type. Three of 4 cases of patients with seizures and the autoscopy of mirror type showed parietooccipital spike foci. Of 13 cases, the seizure focus was left in 6, right in 6, and bilateral in I. SPECT imaging revealed regions of hypoper‐ fusion, usually correlated to regions of EEG spiking. Conclusion: Ictal Doppelganger experiences include features of déjà VLI depersonalization Doppelganger of leibhaftige BewuBtsein and autoscopy. SPECT imaging and interictal EEG demonstrate that the autoscopy of scene type is associated with temporal lobe foci, while autoscopy of mirror type usually is associated with parieto‐ occipital foci. Laterality borc no relevance to the ictal “Doppelganger” experience.