P6-10 Value of dipole analysis and eLORETA in the localization of EEG interictal spikes in epilepsy surgery patients

P6-10 Value of dipole analysis and eLORETA in the localization of EEG interictal spikes in epilepsy surgery patients

S136 discharges. The couse of EEG changes could be: compressive effect of pineal gland cyst on surrounding centrencephalic structures or decreased lev...

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S136 discharges. The couse of EEG changes could be: compressive effect of pineal gland cyst on surrounding centrencephalic structures or decreased levels of melatonine which is considered to have anticonvulsive effect. P6-10 Value of dipole analysis and eLORETA in the localization of EEG interictal spikes in epilepsy surgery patients P.E. Coutin-Churchman1 , L.L.K. Chen1 , K. Shattuck1 , M.R. Nuwer1 Department of Clinical Neurophysiology, University of California Los Angeles, Los Angeles, California, USA

Posters analysis of five discharges identified an occipital localization. Dipoles for the five discharges were co-localized to regions of the fMRI correlate. Conclusions: These results suggest that dipole and fMRI localizations reliably localize epileptic abnormality; however, a single scalp localization may have multiple cerebral sources. This is consistent with the concept that the scalp EEG abnormality is the product of a network that extends beyond the subjacent cerebrum. Both dipole analysis and fMRI are potentially useful tools for analyzing the extent of this network.


Objective: To test the relative accuracy of two different strategies for source localization of interictal spikes. Methods: 20 patients with intractable epilepsy underwent surgery for epileptogenic focus resection. Digital EEG (21 channels 10 20 & T1T2) recorded before surgery was analyzed. Spikes were automatically searched and classified according to morphology and topography, visually screened and averaged. A dipole fitting method (BESA) and a distributed source model (eLORETA) for source localization of interictal spikes was applied to the same data. Results: Both BESA and eLORETA located sources only within the resected area (RA) in 12 patients. BESA located multiple sources, most of them inside RA with few outside RA in 2 patients and eLORETA in 4. Both methods found sources predominantly outside RA, with still some within RA in three patients. BESA showed sources only outside RA in 3 patients and eLORETA in only one. The two methods gave discordant results in 5 patients. The best match to the RA was found in patients with mesiotemporal lobe epilepsy. When analyzing the 37 independent spike clusters found across the 20 patients, BESA located the spike within RA in 22 (59.5%), in the close vicinity (same lobe) in 2, in contralateral homologous areas in 4, in another lobe but still near RA in another 5, and elsewhere in 4. Localization with eLORETA gave sources within RA in 25 cases (67%), in the same lobe in two, in contralateral homologous areas in 4, in another lobe near RA in 4 and elsewhere in 2. Discordances in localization between both methods were found for just 5 of the 37 spikes (p < 0.001). Conclusions: Both BESA and LORETA localized most interictal spikes within the resected area. Some localization discordance was found, and the best match with clinical resection decisions was achieved when using both methods together. P6-11 Comparison of dipole analysis and functional MRI in localization of epileptiform discharges J.M. Stern1 , Z. Haneef1 , S.J. Yeh1 , Y. Okamoto3 , L. Akai2 , J. Parvizi4 , I. Homma2 1 Department of Neurology, Geffen School of Medicine at UCLA, USA, 2 Dept. of Physiology, Showa University School of Medicine, Tokyo, Japan, 3 Dept. of Electrical, Electronics, and Computer Engineering, Chiba Institute of Technology, Japan, 4 Dept. of Neurology, Stanford University School of Medicine, Stanford, CA, USA Objective: Each method for interictal epileptiform discharge localization provides an approximation according to intrinsic limitations. Because dipole source analysis and functional MRI are potentially complementary techniques, we compared each techniques localization of the same discharges to determine their consistency. Methods: Simultaneous EEG and fMRI was recorded using a 3-Tesla MRI (Siemens Trio) and a 32-channel fMRI-compatible EEG device (Kappametrics) that includes reduction of the fMRI-induced noise during imaging. The EEG data was analyzed for source localization of interictal spikes using a dipole tracing method (BS-navi). For each patient, a single discharge location was evaluated. Co-localization of dipoles and fMRI signals were interpreted as regions of epileptic abnormality. Research was according to an IRB-approved protocol. Results: EEGs from three patients were included, comprising two individuals with temporal lobe epilepsy and one with occipital lobe epilepsy. fMRI correlates to midtemporal discharges from one patient localized to: lateral frontal-temporal, paracentral, basal ganglia/thalamus, and posterior temporal. Dipoles for the same discharges were co-localized except for the paracentral region. fMRI correlate to a midtemporal polyspike discharge from another patient was broad temporal and paracentral. Dipoles for the component spikes individually localized with each within the broader region of temporal fMRI signal. Individual occipital pole discharges did not have fMRI correlates, but a combined

P6-12 Analysis of the preceding positive spikes in patients with benign partial epilepsy and febrile seizures H. Yoshinaga1 , K. Kobayashi1 , T. Inoue1 , Y. Ishizaki1 , T. Nakahori1 , Y. Ohtsuka1 1 Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan Objective: Preceding positive spikes (PPS) observed mainly in rolandic spikes are have been attracting attention widely. We analyzed the existence of PPS in spikes observed in EEG of the patients with two types of benign partial epilepsies and those with febrile seizures (FS). Methods: We analyzed spikes in 25 patients with rolandic epilepsy (RE), those in 25 patients with Panayiotopouls syndromes (PS), those in 21 patients with FS by automatic spike analysis system, and compared the ratio of the existence of PPS in spikes among those three groups using sequential mapping methods. Results: (1) Fifteen out of 25 patients with RE and nine out of 17 patients with PS showed PPS in rolandic spikes, whereas only four of 15 patients with FS showed PPS in rolandic spikes. Two out of these four patients with FS later developed afebrile seizures and one of them was diagnosed as having RE. (2) Five out of eight patients with PS showed PPS in occipital spike, whereas only one of six patients with FS showed PPS in occipital spikes. This patient with FS later developed prolonged autonomic febrile seizures. Conclusion: PPS are observed not only in rolandic spikes with RS correlated strictly to silvius seizures, but also in rolandic spikes and occipital spikes with PS. These facts indicate that PPS strongly correlated with epileptogenesis and can be a marker of future development of epilepsy when it is observed in FS patients. P6-13 Ceftazidime induced non-convulsive status epilepticus in a uremic and stroke patient Y.-J. Lin1 , Y.-T. Huang1 , C.-L. Chou1 , H.L. Po1 1 Department of Neurology, Mackay Memorial Hospital, Taipei, Taiwan Objective and Background: Non-convulsive status epilepticus (NCSE) is usually an under-diagnosed and potentially treatable neurologic disorder among patients with altered mental status. Clinical features and ictal electroencephalography (EEG) changes are the most important diagnostic criteria. Stroke, dementia, previous neurosurgery and following some types of antibiotics using had been thought to be remote risk factors. Methods: A case report. Case presentation: A 58-year-old male patient has had history of diabetes with ESRD under hemodialysis for years. He also had multiple cerebral infarction and thalamic hemorrhage with fair recovery except pseudobulbar palsy. He just received amputation for severe PAOD inducing gangrene over left big toe 2 months ago. He was admitted this time due to wound infection. He became mildly confused with irrelevant speech following intravenous Ceftazidime for 4 consecutive doses, and then abnormal right staring with nystagmoid like movement of eyes, shaking of head and filthy language developed 2 days later. A delirium state was also noted. Continuous EEG monitoring showed periodic generalized epileptic discharges which could be partially suppressed by Lorazepam intravenous infusion. Antibiotics were changed to be Piperacillin and anticonvulsant with Phenytoin and Topiramate were used. His consciousness regained in association with absence of abnormal discharging on EEG and he was discharged 3 weeks later. Conclusion: Continuous EEG monitoring should be considered in patients with ESRD and old stroke developing acute mental or conscious change following Ceftazidime treatment to early detect the NCSE, in which antibiotics should be adjusted rapidly to get a good outcome.