Proton magnetic spectroscopy agreed better with magnetic resonance image to lateralization of epileptogenic zone than with surface electroencephalography / Espectroscopia de protons de hidrogenio na investigacao ambulatorial das epilepsias extra-temporais

Objective To analyze the agreement rate of proton magnetic spectroscopy with magnetic resonance image (MRI) and surface electroence-phalography (EEG) in extratemporal neocortical epilepsies. Methods A cross-sectional study, type series of cases included 33 patients, age range 13–59 years old, of both gender, presenting structural alteration identified by MRI (75.8%) or by neurophysiologic techniques (72.7%). The variables were alterations of N-acetyl-aspartate/choline, N-acetyl-aspartate/creatine, choline/creatine, and N-acetyl-aspartate/cho-line+creatine coefficient of asymmetry. Results Agreement rates of lateralization by coefficient of asymmetry of NAA/Cho, NAA/Cr, Co/Cr, and NAA/Cho+Cr with MRI, independent of alteration of surface EEG, were equal to 93.3, 57.9, 15.4, and 93.3%, respectively, modifying to 100, 33.3, 0, and 100%, in 16 patients, with lateralization agreement of MRI and surface EEG. Conclusion Proton magnetic spectroscopy agreed better with MRI to lateralization of epileptogenic zone than with surface EEG. .

Objetivo Analisar a taxa de concordância da espectroscopia de prótons de hidrogênio com imagem de ressonância magnética (IRM) e o eletrencefalograma (EEG) de superfície nas epilepsias neocorticais extratemporais. Métodos Estudo transversal, série de casos, incluiu 33 pacientes, com idade de 13 a 59 anos, de ambos os gêneros, apresentando alteração estrutural à IRM (75,8%) ou neurofisiológica à (72,7%). As variáveis estudadas foram as alterações dos coeficientes de assimetria de N-acetil-aspartato/colina, N-acetil-aspartato/crea-tina, Colina/Creatina e N-acetil-aspartato/colina+creatina. Resultados As taxas de concordância de lateralização dos coeficientes de assimetria de NAA/Co, NAA/Cr, Co/Cr e NAA/Co+Cr com a IRM, independentemente de alterações do EGG de superfície, passaram de 93,3, 57,9, 15,4, 93,3%, respectivamente, para 100, 33,3, zero, 100%, em 16 pacientes, mostrando concordância de lateralização entre IRM e EEG de superfície. Conclusão A espectroscopia de prótons de hidrogênio concordou melhor com a lateralização da zona epileptogênica pela IRM do que com o EEG de superfície. .

Effects of 1 Hz Repetitive Transcranial Magnetic Stimulation on Cortical Excitability and Seizure Reduction in Intractable Neocortical Epilepsy / 대한간질학회지

BACKGROUND & OBJECTIVES: Repetitive transcranial magnetic stimulation (rTMS) can modulate the excitability of cortical networks, possibly reduce the excitability by low frequency stimulation. In this study, we are conducting a study using 1 Hz rTMS in patients with intractable neocortical epilepsy. We wish to see whether 1Hz rTMS induces considerable changes in the cortical excitability and whether it leads to a significant reduction in seizure frequency in individual patients. METHODS: Patients with intractable neocortical epilepsy were recruited, and 1 Hz rTMS (110% of resting motor threshold, 1800 stimuli twice a day) was delivered to the seizure focus for 5 consecutive days. Resting motor threshold (r-MT), MEP amplitudes at different intensities, intracortical inhibition (ICI) and intracortical facilitation (ICF) were measured as TMS indices for motor cortical excitability. TMS measures were repeated before and after daily rTMS session, and again after 2 weeks. RESULTS: Four patients (aged 15 to 53, 3 females and 1 male, 2 TLE and 2 FLE) were described here:cortical excitability in 2 neocortical TLE patients showed lower r-MT and reduced ICF in ipsilateral hemisphere to epileptic focus. One of them with cortical dysplasia showed increased r-MT and ICI, and decreased ICF after daily rTMS session. This patient was seizure-free for 10 weeks, after which the seizure frequency returned to the baseline. CONCLUSIONS: Our preliminary data shows that 1 Hz rTMS may decrease cortical excitability and/or intracortical facilitation, and increase intracortical inhibition after daily rTMS. These findings suggest possible therapeutic effects of low frequency rTMS for patients with intractable neocortical epilepsy.

Limited Predictive Ability of Hippocampal Single Voxel MR Spectroscopy in Surgically Proven Epilepsy

OBJECTIVE: The authors evaluate the predictability of single voxel proton magnetic resonance spectroscopy(MRS) for hippocampal abnormalities in medial temporal lobe epilepsy(MTLE), lateral temporal lobe epilepsy(latTLE) and extratemporal lobe epilepsy(extraTLE). METHODS: Twenty healthy volunteers and 42 patients with MTLE, 17 with latTLE and 23 with extraTLE, were examined preoperatively with MRS. The NAA/(Cho+Cr) ratios were calculated from the MRS peaks obtained bilaterally from both hippocampi. RESULTS: The mean NAA/(Cr+Cho) ratios showed a stepwise increase from the ipsilateral hippocampus in the MTLE group to the normal control group. In the 42 MTLE patients, the mean NAA/(Cho+Cr) ratio value for the ipsilateral hippocampus was 0.39. This was 17.3% lower than the 0.489 measured for the contralateral hippocampus (p=0.005). This was also significantly lower when compared with the hippocampi of latTLE and extraTLE patients ipsilateral to the epileptogenic zone and also with the normal control group (p< 0.05). The mean ratio value of the contralateral hippocampi was also significantly lower when compared with the normal control group (p=0.000). The mean ratio value measured on postoperative MRS showed little metabolic recovery in the MTLE (from 0.455 to 0.481, p=0.48) compared to the latTLE (from 0.438 to 0.52, p=0.09). CONCLUSION: The MRS might be inconclusive in determining whether the non-epileptogenic hippocampus is affected by epileptiform discharge propagation from the epileptogenic hippocampus or from the remote epileptogenic zone other than the hippocampus. Therefore, physicians should be cautious when determining whether the contralateral hippocampus in MTLE or both hippocampi in neocortical epilepsy is abnormal and whether they should be resected together with the epileptogenic zone.

Effect of Seizure on Hippocampus in Mesial Temporal Lobe Epilepsy and Neocortical Epilepsy: MR Spectroscopy Study / 대한간질학회지

PURPOSE: This study was performed to evaluate the effect of seizures on the bilateral hippocampus in mesial temporal lobe epilepsy (mTLE) and neocortical epilepsy by single voxel proton magnetic spectroscopy. METHODS: Forty-one patients with mTLE having unilateral hippocampal sclerosis and 43 patients with a neocortical epilepsy who underwent subsequent epilepsy surgery were recruited. Ninety-five percent confidence intervals of N-acetyl aspartate/choline (NAA/Cho) and NAA/creatine (NAA/Cr) ratios in 20 healthy control subjects were used as threshold values to determine abnormal NAA/Cho and NAA/Cr. The relationship between the results of MRS and the duration of epilepsy, the frequency of seizure, the effect of secondary generalized tonic clonic seizures (2GTCS), and the postsurgical outcome was evaluated. RESULTS: NAA/Cho and NAA/Cr were significantly lower in the ipsilateral hippocampus of mTLE and neocortical epilepsy. NAA/Cho was abnormally low in the ipsilateral hippocampus in 43.9% (18/41) and bilateral hippocampus in 26.8% of mTLE patients. Ipsilateral or bilateral abnormal NAA/Cr was detected in 46.3% (19/41) of mTLE. NAA/Cho was abnormally lower in the ipsilateral hippocampus in 27.9% and bilateral hippocampus in 41.9% of neocortical epilepsy patients. Ipsilateral or bilateral abnormal NAA/Cr was detected in 32.6% of the patients with neocortical epilepsy. Using AIs for patients with bilaterally abnormal ratios of NAA/Cho and NAA/Cr combined with unilateral abnormal ratio, the seizure focus was correctly lateralized in 65.9% of the patients with mTLE and 48.8% of neocortical epilepsy patients. Bilateral NAA/Cho abnormality was significantly related with a poor surgical outcome in mTLE. No significant relationship was found between the results of NAA/Cho or NAA/Cr and the surgical outcome in neocortical epilepsy. The mean contralateral NAA/Cr ratio of the hippocampus in mTLE was significantly lower in patients with a history of the secondary generalized tonic clonic seizure (2GTCS) than in those without it. CONCLUSIONS: Our results demonstrate functional abnormality of the hippocampus in neocortical epilepsy and the relation between 2GTCS and NAA/Cr of the contralateral hippocampus in mTLE. This proves the presence of the seizure effect on the hippocampus in neocortical epilepsy as well as in mTLE.

Interhemispheric Reorganization of Memory Function Assessed by Wada Test in Patients with Mesial Temporal Lobe Epilepsy

BACKGROUND: We investigate an interhemispheric reorganization of memory functions using Wada test in patients with unilateral mesial temporal lobe epilepsy (MTLE). METHODS: We included 70 patients with unilateral MTLE and 37 with neocortical epilepsy (NE). The Wada memory stimuli were composed of 10 items. Scores for each injection were calculated with 1 and 0.5 points assigned for each correct free recall and recognition, respectively. A cut-off asymmetry score for lateralization of memory deficit was defined as 2 points. We statistically analyzed the proportion of memory asymmetry and the average memory score according to the type of epilepsy and the lateralization of seizure focus. RESULTS: The lateralizations of memory deficit determined by Wada memory asymmetry were evenly distributed in the left MTLE (n=34): left in 12 (36%), right in 11 (32%), and undetermined in 11 (32%). However, most (92%) of the right MTLE (n=36) were correctly lateralized to the side of seizure focus. More than 90% of patients with NE were lateralized to right hemisphere regardless of the seizure laterality. The average total (left plus right) memory score were not significantly different between each group. However, right memory score in left MTLE or left memory score in right MTLE were significantly higher than those in NE. The earlier age at seizure onset and the longer duration of epilepsy were observed in patients with left MTLE who had ipsilateral memory deficit comparing to those who had contralateral memory deficit. CONCLUSIONS: A pure interhemispheric reorganization of memory functions could occur in some patients with MTLE. It may be influenced by age at the onset of a seizure and the duration of epilepsy.

Interhemispheric Reorganization of Memory Function Assessed by Wada Test in Patients with Mesial Temporal Lobe Epilepsy

BACKGROUND: We investigate an interhemispheric reorganization of memory functions using Wada test in patients with unilateral mesial temporal lobe epilepsy (MTLE). METHODS: We included 70 patients with unilateral MTLE and 37 with neocortical epilepsy (NE). The Wada memory stimuli were composed of 10 items. Scores for each injection were calculated with 1 and 0.5 points assigned for each correct free recall and recognition, respectively. A cut-off asymmetry score for lateralization of memory deficit was defined as 2 points. We statistically analyzed the proportion of memory asymmetry and the average memory score according to the type of epilepsy and the lateralization of seizure focus. RESULTS: The lateralizations of memory deficit determined by Wada memory asymmetry were evenly distributed in the left MTLE (n=34): left in 12 (36%), right in 11 (32%), and undetermined in 11 (32%). However, most (92%) of the right MTLE (n=36) were correctly lateralized to the side of seizure focus. More than 90% of patients with NE were lateralized to right hemisphere regardless of the seizure laterality. The average total (left plus right) memory score were not significantly different between each group. However, right memory score in left MTLE or left memory score in right MTLE were significantly higher than those in NE. The earlier age at seizure onset and the longer duration of epilepsy were observed in patients with left MTLE who had ipsilateral memory deficit comparing to those who had contralateral memory deficit. CONCLUSIONS: A pure interhemispheric reorganization of memory functions could occur in some patients with MTLE. It may be influenced by age at the onset of a seizure and the duration of epilepsy.

The Usefulness of 3D-Surface Rendering of the MRI in Surgical Treatment of Patients with Intractable Neocortical Epilepsy

BACKGROUND: This study is designed to indicate the role of 3D-surface rendering of the MRI in defining and resect-ing the epileptogenic zone. METHODS: 25 healthy volunteers and 55 patients were studied. Conventional MRI and 3D-surface rendering were performed. Sulcal and gyral patterns were assesed by a neuroradiologist and a neurologist with-out the clinical informations. Chronic video-EEG monitoring with surface and subdural grid electrodes, and PET were done. Resection was performed based on data of the EEG recordings and 3D-surface rendering. RESULTS: Conventional MRI identified structural abnormality ("MRI-identifiable lesion") in 20 patients. 20 of 35 patients without structural abnormality in conventional MRI revealed abnormal sulcal and gyral patterns in 3D-surface rendering of MRI ("3D-identifiable lesion"). Subdural grid EEGs recorded focal or diffuse ictal EEG onset from the region of "3D-identifiable lesion". Histopathologic findings revealed cortical dysplasia in 48 and neocortical gliosis in seven. Overall surgical out-come, at the average follow up period of 32.5 months, showed class I in 63.6%, class II in 25.5%, and class III in 10.9%. Among 20 patients with "MRI-identifiable lesion", 80% were in class I and 20% were in class II. Among 35 patients without "MRI-identifiable lesion", 54.3% were in class I, 28.6% were class II, and 17.1% were in class III. 80% of 20 patients with "3D-identifiable lesion" showed class I and 20% of 15 patients without "3D-identifiable lesion" showed class I. CONCLUSIONS: Identification of "MRI-identifiable lesion" or "3D-identifiable lesion" was of value in defining the epileptogenic zone. Resection of "MRI-identifiable lesion" or "3D-identifiable lesion", which were epilep-togenic in EEGs, promised a good surgical outcome.

Analysis of Ictal Electrocorticographic Features in Nonlesional Neocortical Epilepsy / 대한간질학회지

BACKGROUND: To characterize the ictal electrocorticographic features in relation to surgical outcome in nonlesional neocortical epilepsy (NE). METHODS: Seventeen patients with intractable NE underwent surgeries after chronic subdural recordings. All patients did not have any lesions on brain MRI, which was confirmed by pathology postoperatively. One hundred and eighty one ictal EEGs recorded from subdural electrodes were analyzed. Surgical outcome was determined by seizure reduction rate, and free or more than 75% reduction was defined as favorable outcome. The mean duration of follow-up was 55+/-8.7 months. RESULTS: Reproducible ictal onset zone (IOZ) in more than a half of seizures (p=0.002), and persistent ictal discharges in IOZ from the onset to the end of seizure were found more frequently in the patients with good outcome (p=0.004). Ictal onset patterns consisting of low voltage fast or high amplitude beta spikes predicted a good surgical outcome while rhythmic sinusoidal activity or rhythmic spike/sharp wave were predictive of poor outcome (p=0.01). The ictal onset rhythm consisted of gamma or beta frequencies was more prevalent in the favorable group (p=0.003). CONCLUSIONS: The presence of stable ictal circuit suggested by the consistent earliest activation in more than 50% of seizures and the active participation of IOZ throughout the attack were valuable prognostic factors in addition to the morphology and frequency of ictal onset rhythm.

The Clinical Usefulness of Ictal Surface EEG in Neocortical Epilepsy

BACKGROUND: Localizable scalp ictal EEG appears to be rare in neocortical epilepsy. However, there have not been many studies based upon a large number of patients. This study aims to identify the characteristic patterns of variable neocortical epilepsies and to evaluate their clinical usefulness in the localization of epileptogenic foci. METHODS: We retrospectively assessed 394 noninvasive ictal recordings from 86 patients who subsequently underwent invasive study and resective surgery. Ictal EEGs were recorded by video-EEG monitoring systems with electrodes placed according to the international 10-20 system including additional anterior temporal electrodes. Ictal recordings were analyzed accord-ing to the localizing accuracy and frequency characteristics. The durations of discrete or regional ictal rhythms were also measured. RESULTS: The percentage of discrete or regional EEGs were respectively 26, 52, 70, and 10% in frontal lobe epilepsy (FLE), lateral temporal lobe epilepsy, occipital lobe epilepsy (OLE), and parietal lobe epilepsy (PLE). The ictal rhythms in the order of frequency were theta, delta, beta, alpha, and rhythmic spike-and-wave. The duration of discrete or regional ictal rhythms were significantly shorter in FLE and PLE than in other epilepsies. Ictal beta activ-ity was the most common rhythm in discrete-patterned EEGs. There were some tendencies of poor lateralization in the presence of structural lesion. Types of seizure were not related with the degree of localization except for simple partial seizure. CONCLUSIONS: Ictal surface EEG was clinically helpful in the localization of epileptogenic foci especially in particular neocortical epileptic syndromes.