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P6-6 Is interictal EEG enough to predict seizure freedom in mesial temporal lobe epilepsy with hippocampal sclerosis?
29th International Congress of Clinical Neurophysiology
S135
P6-6 Is interictal EEG enough to predict seizure freedom in mesial temporal lobe epilepsy with hippocampal sclerosis?
P6-8 Interplay of hippocampal interictal spikes and normal physiological oscillations in the production of transient working memory disruptions
J.M. Chung1 , J.R. Soss2 , J. Engel Jr.2 Cedars-Sinai Medical Center Dept. of Neurology, Los Angeles, California, USA, 2 UCLA Seizure Disorder Center, Los Angeles, California 90095, USA
J. Kleen1 , B. Jobst1 , K. Kulandaivel1 , T. Darcey1 , G. Holmes1 , K. Bujarski1 , V. Thadani1 , P.-P. Lenck-Santini1 1 Dartmouth Medical School, Hanover, NH, USA
1
Objective: Previous studies have shown that unilateral or predominantly unilateral interictal epileptic discharges (IED) are associated with good outcome in patients undergoing surgery for TLE. We decided to investigate which interictal EEG patterns correlate with good outcome in patients with MTLE and pathologically proven hippocampal sclerosis (HS). Methods: We identified 32 patients with intractable TLE treated at UCLA between January 1995 and December 2003, with pathologically proven HS. For each patient, 30 minutes of awake and 60 minutes of sleep interictal EEG were reviewed, and IED were quantified at each electrode location. Results: Seizure freedom was evaluated at two years post-operatively. Twenty-seven of 32 patients remained seizure-free. In 26 patients with IED confined to the temporal lobe and localized to F7, T1, T3 or F8, T2, T4 electrodes during the EEG, all were seizure-free. In four patients with bilateral independent IED, one was seizure-free. Neither of the two patients with unilateral IED that extended beyond the temporal region (extended to the F3, O1, T6, and O2 electrodes) was seizure-free. Of the two patients who had strictly unilateral IED in the awake EEG and occasional IED in the contralateral temporal region in the sleep EEG, one remained seizure-free at two years post-operatively. Conclusions: These results suggest that in a subset of patients with pure MTLE (pathologically proven HS with good surgical outcome), IED which are exclusively unilateral during wakefulness and near exclusively unilateral during sleep purports a better surgical outcome. This suggests that patients with MTLE, HS, and unilateral IED are more likely to be seizure free after surgery than those with predominantly unilateral IED, regardless of the ictal recordings. Further study is underway. P6-7 Clinical utility of EEG dipole analysis in the preoperative evaluation of epilepsy surgery patients A. Amandusson1 , R. Flink1 1 Department of Clinical Neurophysiology, Uppsala University Hospital, Uppsala, Sweden Objective: Dipole analysis is a non-invasive and easily accessible method for source localization of epileptogenic foci. Its reliability has been questioned, however, and its utility in the presurgical evaluation of patients with partial epilepsy has not been fully established. In this prospective study we evaluated whether dipole analysis provided any important information in addition to that already obtained by using conventional EEG and/or neuroimaging in the presurgical work-up of resective epilepsy surgery. Methods: Long-term scalp EEG-recordings (21 electrodes) were obtained from 24 patients with intractable epilepsy. The exact locations of the electrodes were obtained using a Polhemus digitizer and Etrak software on each patient and superimposed on a standard MRI head model. Single spike and sharp-wave potentials were then analyzed using the ASA software calculating single rotating dipoles and excluding all dipoles with a goodness of fit value <90%. The dipole location was then superimposed on the standard MRI and compared with the results of video-EEG, MRI and SPECT/PET. The results of the dipole studies were presented continuously at the weekly meetings of the epilepsy surgery team and it was noted whether the results affected epilepsy surgery decision-making or, when applicable, the strategy for subsequent intracranial EEG-recordings. Results: Preliminary data show that in 60% of the patients, the localization of EEG dipoles was concordant with that of other findings (conventional EEG and/or neuroimaging). In most of these patients, dipole analysis provided important information for epilepsy surgery decision-making or contributed to the strategy for subsequent intracranial EEG-recordings. In 40% of the patients, the dipole analysis was inconclusive. These patients were either MRI negative or had extensive bilateral migration disorder. Data on specific subgroups will be presented. Conclusions: Interictal EEG dipole analysis is a helpful tool in epilepsy surgery decision-making. Its utility, however, may be limited to certain subgroups of patients.
Objective: Numerous epileptiform abnormalities occur in the hippocampus of patients with temporal lobe epilepsy (TLE). Previous work in our laboratory using an animal model has shown that hippocampal interictal spikes (HIS) disrupt the retrieval of information in working memory, but not encoding or storage. Patterns of normal electrophysiological oscillations (e.g. theta rhythm, 4 8 Hz) are associated with these cognitive processes, and these activities may be transiently affected by the occurrence of HIS, via the integration of local neurons into the aberrant firing burst. We aimed to determine whether HIS in human patients implanted with hippocampal depth electrodes could potentially disrupt cognitive processes by interfering with normal functional brain rhythms. Methods: We analyzed the hippocampal EEG activity of patients implanted with depth electrodes for medically refractory temporal lobe epilepsy, while they performed the Sternberg task of working memory. HIS were marked in the EEGs from hundreds of trials by an experienced epileptologist. Oscillation phase was calculated using the Hilbert transform and analyzed using the Rayleigh circular statistic. Coherence between hippocampal and cortical electrode sites was calculated for multiple frequency bands. Results: HIS were associated with disruptions in cognition for some but not all patients. Theta oscillations were differentially phase-locked to the encoding and retrieval components of correct trials (p < 10 10 ), but not among incorrect trials. Theta coherence between bilateral hippocampi and adjacent cortex was high during encoding and retrieval for most lead pairs. HIS disrupted the continuity of theta phase and the oscillation coherence of a number of lead pairs. Conclusions: These results suggest that accurate performance of a working memory task likely relies on phase-reset and coherence of theta oscillations. Transient epileptiform abnormalities such as HIS can potentially disrupt these processes producing brief lapses in performance, a potential mechanism for a proportion of the cognitive impairment so common in epilepsy. P6-9 Electroencephalography in patients with pineal gland cyst and epilepsy J. Bosnjak1 , S. Miskov1 , H. Hecimovic1 , V. Seric1 , V. Demarin1 Department of Neurology, University Hospital Sestre Milosrdnice, Zagreb, Croatia
1
Objective: Pineal gland cyst can couse various clinical implications. The most common symptoms include: headache, vertigo, visual and oculomotor disturbancies, epilepsy and obstructive hydrocephalus. In series of magnetic resonance (MR) studies, the prevalence ranges between 1.3% and 4.3% of patients examined for various neurological reasons and in up to 10.8% of asymptomatic volunteers. The aim of this study is to determine EEG (electroencephalography) changes in patients with pineal gland cyst, focusing primarily on those patients with epilepsy as presenting symptome. Methods: We prospectivelly analyzed 69 patients complaining of various neurological symptomes (48 female, mean age 26.44±15.95 years and 21 male, mean age 22.48±16.66 years) with pineal gland cyst detected on MR of the brain. In patients with epilepsy, pineal gland cysts varied in size from 10×9×5 mm to 21×17×15 mm. Four patients had compression on superior colliculi described on MR of the brain. Results: Epilepsy was presenting symptom in 19 of 69 patients. Absance seizures were present in 3 patients, grand mal in 3 patients, simple partial seizures in 2 patients, partial seizures secondarily generalized in 6 and complex partial seizures in 3 patients. In 14 patients with epilepsy EEG showed: focal spikes or biphasic spikes, spike and wave complex 6 7 Hz focally or diffuse paroxismal discharges, spike and wave complex 3 4 Hz focally or diffuse paroxismal disharges whereas remaining had nonspecific changes: focal slowing and dysrrhytmic changes. Conclusions: Patients with cystic lesion of pineal gland and epilepsy can have abnormal EEG findings. In our patients specific epileptogenic graphoelements were seen in 14 patients with epilepsy as presenting symptome. Other patients may have focal slowing or diffuse disrrhytmic
S135
P6-6 Is interictal EEG enough to predict seizure freedom in mesial temporal lobe epilepsy with hippocampal sclerosis?
P6-8 Interplay of hippocampal interictal spikes and normal physiological oscillations in the production of transient working memory disruptions
J.M. Chung1 , J.R. Soss2 , J. Engel Jr.2 Cedars-Sinai Medical Center Dept. of Neurology, Los Angeles, California, USA, 2 UCLA Seizure Disorder Center, Los Angeles, California 90095, USA
J. Kleen1 , B. Jobst1 , K. Kulandaivel1 , T. Darcey1 , G. Holmes1 , K. Bujarski1 , V. Thadani1 , P.-P. Lenck-Santini1 1 Dartmouth Medical School, Hanover, NH, USA
1
Objective: Previous studies have shown that unilateral or predominantly unilateral interictal epileptic discharges (IED) are associated with good outcome in patients undergoing surgery for TLE. We decided to investigate which interictal EEG patterns correlate with good outcome in patients with MTLE and pathologically proven hippocampal sclerosis (HS). Methods: We identified 32 patients with intractable TLE treated at UCLA between January 1995 and December 2003, with pathologically proven HS. For each patient, 30 minutes of awake and 60 minutes of sleep interictal EEG were reviewed, and IED were quantified at each electrode location. Results: Seizure freedom was evaluated at two years post-operatively. Twenty-seven of 32 patients remained seizure-free. In 26 patients with IED confined to the temporal lobe and localized to F7, T1, T3 or F8, T2, T4 electrodes during the EEG, all were seizure-free. In four patients with bilateral independent IED, one was seizure-free. Neither of the two patients with unilateral IED that extended beyond the temporal region (extended to the F3, O1, T6, and O2 electrodes) was seizure-free. Of the two patients who had strictly unilateral IED in the awake EEG and occasional IED in the contralateral temporal region in the sleep EEG, one remained seizure-free at two years post-operatively. Conclusions: These results suggest that in a subset of patients with pure MTLE (pathologically proven HS with good surgical outcome), IED which are exclusively unilateral during wakefulness and near exclusively unilateral during sleep purports a better surgical outcome. This suggests that patients with MTLE, HS, and unilateral IED are more likely to be seizure free after surgery than those with predominantly unilateral IED, regardless of the ictal recordings. Further study is underway. P6-7 Clinical utility of EEG dipole analysis in the preoperative evaluation of epilepsy surgery patients A. Amandusson1 , R. Flink1 1 Department of Clinical Neurophysiology, Uppsala University Hospital, Uppsala, Sweden Objective: Dipole analysis is a non-invasive and easily accessible method for source localization of epileptogenic foci. Its reliability has been questioned, however, and its utility in the presurgical evaluation of patients with partial epilepsy has not been fully established. In this prospective study we evaluated whether dipole analysis provided any important information in addition to that already obtained by using conventional EEG and/or neuroimaging in the presurgical work-up of resective epilepsy surgery. Methods: Long-term scalp EEG-recordings (21 electrodes) were obtained from 24 patients with intractable epilepsy. The exact locations of the electrodes were obtained using a Polhemus digitizer and Etrak software on each patient and superimposed on a standard MRI head model. Single spike and sharp-wave potentials were then analyzed using the ASA software calculating single rotating dipoles and excluding all dipoles with a goodness of fit value <90%. The dipole location was then superimposed on the standard MRI and compared with the results of video-EEG, MRI and SPECT/PET. The results of the dipole studies were presented continuously at the weekly meetings of the epilepsy surgery team and it was noted whether the results affected epilepsy surgery decision-making or, when applicable, the strategy for subsequent intracranial EEG-recordings. Results: Preliminary data show that in 60% of the patients, the localization of EEG dipoles was concordant with that of other findings (conventional EEG and/or neuroimaging). In most of these patients, dipole analysis provided important information for epilepsy surgery decision-making or contributed to the strategy for subsequent intracranial EEG-recordings. In 40% of the patients, the dipole analysis was inconclusive. These patients were either MRI negative or had extensive bilateral migration disorder. Data on specific subgroups will be presented. Conclusions: Interictal EEG dipole analysis is a helpful tool in epilepsy surgery decision-making. Its utility, however, may be limited to certain subgroups of patients.
Objective: Numerous epileptiform abnormalities occur in the hippocampus of patients with temporal lobe epilepsy (TLE). Previous work in our laboratory using an animal model has shown that hippocampal interictal spikes (HIS) disrupt the retrieval of information in working memory, but not encoding or storage. Patterns of normal electrophysiological oscillations (e.g. theta rhythm, 4 8 Hz) are associated with these cognitive processes, and these activities may be transiently affected by the occurrence of HIS, via the integration of local neurons into the aberrant firing burst. We aimed to determine whether HIS in human patients implanted with hippocampal depth electrodes could potentially disrupt cognitive processes by interfering with normal functional brain rhythms. Methods: We analyzed the hippocampal EEG activity of patients implanted with depth electrodes for medically refractory temporal lobe epilepsy, while they performed the Sternberg task of working memory. HIS were marked in the EEGs from hundreds of trials by an experienced epileptologist. Oscillation phase was calculated using the Hilbert transform and analyzed using the Rayleigh circular statistic. Coherence between hippocampal and cortical electrode sites was calculated for multiple frequency bands. Results: HIS were associated with disruptions in cognition for some but not all patients. Theta oscillations were differentially phase-locked to the encoding and retrieval components of correct trials (p < 10 10 ), but not among incorrect trials. Theta coherence between bilateral hippocampi and adjacent cortex was high during encoding and retrieval for most lead pairs. HIS disrupted the continuity of theta phase and the oscillation coherence of a number of lead pairs. Conclusions: These results suggest that accurate performance of a working memory task likely relies on phase-reset and coherence of theta oscillations. Transient epileptiform abnormalities such as HIS can potentially disrupt these processes producing brief lapses in performance, a potential mechanism for a proportion of the cognitive impairment so common in epilepsy. P6-9 Electroencephalography in patients with pineal gland cyst and epilepsy J. Bosnjak1 , S. Miskov1 , H. Hecimovic1 , V. Seric1 , V. Demarin1 Department of Neurology, University Hospital Sestre Milosrdnice, Zagreb, Croatia
1
Objective: Pineal gland cyst can couse various clinical implications. The most common symptoms include: headache, vertigo, visual and oculomotor disturbancies, epilepsy and obstructive hydrocephalus. In series of magnetic resonance (MR) studies, the prevalence ranges between 1.3% and 4.3% of patients examined for various neurological reasons and in up to 10.8% of asymptomatic volunteers. The aim of this study is to determine EEG (electroencephalography) changes in patients with pineal gland cyst, focusing primarily on those patients with epilepsy as presenting symptome. Methods: We prospectivelly analyzed 69 patients complaining of various neurological symptomes (48 female, mean age 26.44±15.95 years and 21 male, mean age 22.48±16.66 years) with pineal gland cyst detected on MR of the brain. In patients with epilepsy, pineal gland cysts varied in size from 10×9×5 mm to 21×17×15 mm. Four patients had compression on superior colliculi described on MR of the brain. Results: Epilepsy was presenting symptom in 19 of 69 patients. Absance seizures were present in 3 patients, grand mal in 3 patients, simple partial seizures in 2 patients, partial seizures secondarily generalized in 6 and complex partial seizures in 3 patients. In 14 patients with epilepsy EEG showed: focal spikes or biphasic spikes, spike and wave complex 6 7 Hz focally or diffuse paroxismal discharges, spike and wave complex 3 4 Hz focally or diffuse paroxismal disharges whereas remaining had nonspecific changes: focal slowing and dysrrhytmic changes. Conclusions: Patients with cystic lesion of pineal gland and epilepsy can have abnormal EEG findings. In our patients specific epileptogenic graphoelements were seen in 14 patients with epilepsy as presenting symptome. Other patients may have focal slowing or diffuse disrrhytmic