BACKGROUND: Anteromesial temporal resection (AMTR) is well established as effective in patients with intractable mesial temporal epilepsy. However, little electroclinical information is available relevant to poor surgical outcome after AMTR. We examined the postoperative electroclinical features based on postoperative MRI and video-EEG monitoring (VEM) in patients with poor surgical outcome. METHODS: We reviewed clinical features and postoperative VEM results in 20 patients with failure in AMTR. According to the postoperative electroclinical features, we classified them into mesial temporal (MT), bitemporal (BT), extramesial temporal (XMT), combined (C), and unclassified groups. The postoperative VEM results were compared among the groups. Surgical outcome was assessed in five patients who underwent reoperation. RESULTS: Patients comprised 6 MT, 2 BT, 6 XMT, 1 C, and 6 unclassified. Aura and automatism were more frequent in MT (50.0%, 83.3%) than in XMT (16.7%, 33.3%). Theta to delta rhythm, during the ictal onset and build-up period, was more frequent in MT (83.3%, 66.7%) than in XMT (33.3%, 33.3%). The ictal onset and build-up pattern of ictal EEG were most frequently localized to the frontotemporal region in MT (66.7%, 100.0%), while there was no predominantly localized region in XMT. The surgical outcome after reoperation was better in MT group than in XMT and C groups. CONCLUSIONS: Postoperative MRI and VEM are useful to assess the postoperative electroclinical features in failed AMTR. Reoperation of the residual mesiotemporal structures after confirming epileptogenic foci may have good surgical outcome.
Automatism ; Delta Rhythm ; Electroencephalography ; Epilepsy ; Humans ; Reoperation ; Seizures

BACKGROUND: Anesthesia induces the spectral changes in EEG. Attempts to relate these spectral changes to adequacy of anesthesia have been hindered due to the complex waveforms of EEG. The objective of this investigation is to monitor the awareness of patients during cesarean section by means of EEG spectral analysis. METHODS: 20 patients for cesarean section aged from 24 to 39 and ASA class I or II, were maintained with O2(50%)-N2O(50%)-enflurane(0.8%). And they were administered with midazolam(0.07 mg/kg) in group I(n=6), fentanyl(1 microgram/kg) in group II(n=7), and fentanyl(2 microgram/kg) in group III(n=7) after birth. The density of each spectral band in EEG (delta 1-3.25 Hz, theta 3.5-7.75 Hz, alpha 8-12.15 Hz and beta 13-31.75Hz) was analyzed to derive total density, delta ratio and median power frequency. RESULTS: The spectral data demonstrated that the alpha rhythm was dominant in pre-induction period and beta rhythm was abundant both in the immediate post-induction period and after birth for all three groups. Delta ratio and median power frequency decreased after injection of midazolam and fentanyl in all three groups. None of patients could recall the memory about experience during cesarean section. CONCLUSIONS: These findings indicate that EEG spectral analysis is potentially useful to determine the changes of cerebroelectrical activity but difficult to monitor the awareness of patients during cesarean section.
Alpha Rhythm ; Anesthesia ; Anesthetics ; Anesthetics, Intravenous* ; Beta Rhythm ; Cesarean Section* ; Electroencephalography* ; Enflurane ; Female ; Fentanyl ; Humans ; Isoflurane ; Memory ; Midazolam ; Parturition ; Pregnancy

Epileptic spike is an indicator of hyper-excitability and hyper-synchrony in the neural networks. The inhibitory effects of spikes on theta rhythms (4-8 Hz) might be helpful to understand the mechanism of epileptic damage on the cognitive functions. To quantitatively evaluate the inhibitory effects of spikes on theta rhythms, intracerebral electroencephalogram (EEG) recordings with both sporadic spikes (SSs) and spike-free transient period between adjacent spikes were selected in 4 patients in the status of rapid eyes movement (REM) sleep with temporal lobe epilepsy (TLE) under the pre-surgical monitoring. The electrodes of hippocampal CA3 and entorhinal cortex (EC) were employed, since CA3 and EC built up one of key loops to investigate cognition and epilepsy. These SSs occurred only in CA3, only in EC, or in both CA3 and EC synchronously. Theta power was respectively estimated around SSs and during the spike-free transient period by Gabor wavelet transform and Hilbert transform. The intermittent extent was then estimated to represent for the loss of theta rhythms during the spike-free transient period. The following findings were obtained: (1) The prominent rhythms were in theta frequency band; (2) The spikes could transiently reduce theta power, and the inhibitory effect was severer around SSs in both CA3 and EC synchronously than that around either SSs only in EC or SSs only in CA3; (3) During the spike-free transient period, theta rhythms were interrupted with the intermittent theta rhythms left and theta power level continued dropping, implying the inhibitory effect was sustained. Additionally, the intermittent extent of theta rhythms was converged to the inhibitory extent around SSs; (4) The average theta power level during the spike-free transient period might not be in line with the inhibitory extent of theta rhythms around SSs. It was concluded that the SSs had negative effects on theta rhythms transiently and directly, the inhibitory effects aroused by SSs sustained during the spike-free transient period and were directly related to the intermittent extent. It was indicated that the loss of theta rhythms might qualify exactly the sustained inhibitory effects on theta rhythms aroused by spikes in EEG. The work provided an argumentation about the relationship between the transient negative impact of interictal spike and the loss of theta rhythms during spike-free activity for the first time, offered an intuitive methodology to estimate the inhibitory effect of spikes by EEG, and might be helpful to the analysis of EEG rhythms based on local field potentials (LFPs) in deep brain.
CA3 Region, Hippocampal ; physiopathology ; Electroencephalography ; Entorhinal Cortex ; physiopathology ; Epilepsy, Temporal Lobe ; physiopathology ; Humans ; Male ; Theta Rhythm

Stimulation of the medial forebrain bundle (MFB) can reinforce intracranial self-stimulation (ICSS) in rodents (i.e., reward-seeking behavior). The MFB stimulation produces a highly reliable behavioral output that enabled a clear distinction of the animal behavioral states between the non-ICSS and ICSS periods. However, the cortical states during these reward-seeking behaviors are not fully characterized in comparison to those during volitional behavior. This study was designed to characterize the cortical rhythms of and coherence between prefrontal cortex and hippocampus during the wheel-turning behavior reinforced by the ICSS in comparison to the wheel-turning without ICSS. We used a wheel for freely moving mice, which was programmed to deliver cathode currents through an electrode in the MFB at each one-quarter turn of the wheel to induce ICSS. The wheel-turning epochs were extracted from the pre-ICSS, ICSS and post-ICSS sessions and the prefrontal EEGs and the hippocampal LFPs in the epochs were analyzed with power and synchronization analyses. During the ICSS, the EEG power decreased at 6~10 Hz in the prefrontal cortex, while was not significantly altered in the hippocampus. Furthermore, we found that the phase synchrony between the prefrontal cortex and the hippocampus corresponding to information transmission between the two regions during reward-seeking motion decreased preceding MFB stimulation reinforced by ICSS. Our findings suggest that theta-activity can be reliably dissociated from active behavior if the animal is involved in self-stimulation.
Animals ; Behavior, Animal ; Electrodes ; Electroencephalography ; Hippocampus ; Medial Forebrain Bundle* ; Mice* ; Prefrontal Cortex* ; Rodentia ; Theta Rhythm

The main shortcomings of using electrocortical stimulation (ECS) in identifying the motor functional area around the focus in neurosurgery are certainly time-consuming, possibly cerebral cortex injuring and perhaps triggering epilepsy. To solve these problems, we in our research presented an intraoperative motor cortex functional mapping based on electrocorticography (ECoG). At first, using power spectrum estimation, we analyzed the characteristic of ECoG which was related to move task, and selected Mu rhythm as the move-related feature. Then we extracted the feature from original ECoG by multi-resolution wavelet analysis. By calculating the sum value of feature in every channel and observing the distribution of these sum values, we obtained the correlation between the cortex area under the electrode and motor cortex functional area. The results showed that the distribution of the relationship between the cortex under the electrode and motor cortex functional area was almost consistent with those identified by ECS which was called as the gold-standard. It indicated that this method was basically feasible, and it just needed five minutes totally. In conclusion, ECoG-based and passive identification of motor cortical function may serve as a useful adjunct to ECS in the intraoperative mapping.
Brain Mapping ; Electric Stimulation ; Electrocorticography ; Electrodes, Implanted ; Electroencephalography ; Epilepsy ; Humans ; Motor Cortex ; physiology ; Wavelet Analysis

BACKGROUNDTo study the characters of high-frequency oscillations (HFOs) in the seizure onset zones (SOZ) and the nonseizure onset zones (NSOZ) in the electrocorticography (ECoG) of patients with neocortical epilepsy.

METHODSOnly patients with neocortical epilepsy who were seizure-free after surgery as determined with ECoG were included. We selected patients with normal magnetic resonance imaging before surgery in order to avoid the influence of HFOs by other lesions. Three minutes preictal and 10 min interictal ECoG as recorded in 39 channels in the SOZ and 256 channels in the NSOZ were analyzed. Ripples and fast ripples (FRs) were analyzed by Advanced Source Analysis software (ASA, The Netherlands). Average duration of HFOs was analyzed in SOZ and NSOZ separately.

RESULTSFor ripples, the permillage time occupied by HFOs was 0.83 in NSOZ and 1.17 in SOZ during the interictal period. During preictal period, they were 2.02 in NSOZ and 7.93 in SOZ. For FRs, the permillage time occupied by HFOs was 0.02 in NSOZ and 0.42 in SOZ during the interictal period. During preictal period, they were 0.03 in NSOZ and 2 in SOZ.

CONCLUSIONSHigh-frequency oscillations are linked to SOZ in neocortical epilepsy. Our study demonstrates the prevalent occurrence of HFOs in SOZ. More and more burst of HFOs, especially FRs, means the onset of seizures.

Adolescent ; Adult ; Child ; Electrocorticography ; Electroencephalography ; Epilepsy ; physiopathology ; Female ; Humans ; Male ; Seizures ; physiopathology ; Young Adult

This study investigates the sensitivity and specificity of predicting epileptic seizures from intracranial electroencephalography (iEEG). A monitoring system is studied to generate an alarm upon detecting a precursor of an epileptic seizure. The iEEG traces of ten patients suffering from medically intractable epilepsy were used to build a prediction model. From the iEEG recording of each patient, power spectral densities were calculated and classified using support vector machines. The prediction results varied across patients. For seven patients, seizures were predicted with 100% sensitivity without any false alarms. One patient showed good sensitivity but lower specificity, and the other two patients showed lower sensitivity and specificity. Predictive analytics based on the spectral feature of iEEG performs well for some patients but not all. This result highlights the need for patient-specific prediction models and algorithms.
Drug Resistant Epilepsy ; Electrocorticography* ; Electroencephalography ; Epilepsy* ; Humans ; Seizures ; Sensitivity and Specificity ; Support Vector Machine

Drug-refractory epilepsy (DRE) may be treated by surgical intervention. Intracranial EEG has been widely used to localize the epileptogenic zone (EZ). Most studies of epileptic network focus on the features of EZ nodes, such as centrality and degrees. It is difficult to apply those features to the treatment of individual patients. In this study, we proposed a spatial neighbor expansion approach for EZ localization based on a neural computational model and epileptic network reconstruction. The virtual resection method was also used to validate the effectiveness of our approach. The electrocorticography (ECoG) data from 11 patients with DRE were analyzed in this study. Both interictal data and surgical resection regions were used. The results showed that the rate of consistency between the localized regions and the surgical resections in patients with good outcomes was higher than that in patients with poor outcomes. The average deviation distance of the localized region for patients with good outcomes and poor outcomes were 15 mm and 36 mm, respectively. Outcome prediction showed that the patients with poor outcomes could be improved when the brain regions localized by the proposed approach were treated. This study provides a quantitative analysis tool for patient-specific measures for potential surgical treatment of epilepsy.
Humans ; Epilepsy/surgery* ; Brain/surgery* ; Electrocorticography/methods* ; Drug Resistant Epilepsy/surgery* ; Brain Mapping/methods* ; Electroencephalography/methods*

BACKGROUND AND PURPOSE: The purpose of this study was to characterize abnormal cortical activity during sleep in restless legs syndrome (RLS) patients and to determine the effects of treatment with a dopamine agonist. Based on whole-brain electroencephalograms, we attempted to verify alterations in the functional network as well as the spectral power of neural activities during sleep in RLS patients and to determine whether the changes are reversed by treatment with pramipexole. METHODS: Twelve drug-naïve RLS patients participated in the study. Overnight polysomnography was performed before and after treatment: the first recording was made immediately prior to administering the first dose of pramipexole, and the second recording was made 12–16 weeks after commencing pramipexole administration. Sixteen age-matched healthy participants served as a control group. The spectral power and interregional phase synchrony were analyzed in 30-s epochs. The functional characteristics of the cortical network were quantified using graph-theory measures. RESULTS: The delta-band power was significantly increased and the small-world network characteristics in the delta band were disrupted in RLS patients compared to the healthy controls. These abnormalities were successfully treated by dopaminergic medication. The delta-band power was significantly correlated with the RLS severity score in the RLS patients prior to treatment. CONCLUSIONS: Our findings suggest that the spectral and functional network characteristics of neural activities during sleep become abnormal in RLS patients, and these abnormalities can be successfully treated by a dopamine agonist.
Delta Rhythm* ; Dopamine Agonists* ; Dopamine* ; Electroencephalography ; Healthy Volunteers ; Humans ; Polysomnography ; Restless Legs Syndrome*

Traditional sleep scoring system describes the sleep EEG characterized by features in time domain as well as frequency domain. Power Spectral Density (PSD) is one of the well-used methods to observe the occurrence of specified rhythms. However, the parameter model based PSD estimation is used with the assumption that the model order is determined as low as possible through prior knowledge. This paper briefs the development of Autoregressive Model Order (ARMO) criterion, and provides the distribution of ARMOs for specified sleep EEG, which shows that ARMOs concentrate on several well separated regions that are indicative of the microstructure and transition states. This study suggests the promising perspective of ARMO as a special EEG feature for weighing complexity, randomness and rhythm components.
Delta Rhythm ; Electroencephalography ; Humans ; Models, Neurological ; Regression Analysis ; Signal Processing, Computer-Assisted ; Sleep Stages ; physiology