scholarly journals Functional and Anatomic Correlates of Two Frequently Observed Temporal Lobe Seizure-Onset Patterns

2000 ◽  
Vol 7 (1-2) ◽  
pp. 49-63 ◽  
Author(s):  
Ana Luisa Velascol ◽  
Charles L. Wilson ◽  
Thomas L. Babb ◽  
Jerome Engel Jr
Keyword(s):  
Temporal Lobe ◽  
Low Voltage ◽  
Low Frequency ◽  
Neuronal Loss ◽  
High Amplitude ◽  
Seizure Onset ◽  
Depth Electrodes ◽  
Cell Counts ◽  
Number Of Patients ◽  
Temporal Lobe Seizure

Intracranial depth electrode EEG records of 478 seizures, recorded in 68 patients undergoing diagnostic monitoring with depth electrodes, were evaluated to investigate the correlates of electrographic onset patterns in patients with temporal lobe seizures. The seizure onsets in 78% of these patients were identified as either hypersynchronous onsets, beginning with low-frequency, high-amplitude spikes, or low-voltage fast (LVF) onsets, increasing in amplitude as the seizure progressed. The number of patients (35) having hypersynchronous seizure onsets was nearly twice that of patients (18) having LVF onsets. Three major differences were seen among patients with the two seizure-onset patterns. When compared with patients having LVF onsets, patients with hypersynchronous seizure onsets had a significantly greater probability of having (1) focal rather than regional seizure onsets (p<0.01), (2) seizures spreading more slowly to the contralateral mesial temporal lobe (p<0.003), and (3) cell counts in resected hippocampal tissue showing greater neuronal loss (p<0.001). The results provide evidence that the most frequent electrographic abnormality associated with mesial temporal seizures is local hypersynchrony, a condition associated with major neuronal-loss in the hippocampus. The results also indicate that LVF seizure onsets more frequently represent widely distributed discharges, which interact with and spread more rapidly to surrounding neocortical areas.

scholarly journals Multiple ictal onset patterns underlie seizure generation in seizure-free patients with temporal lobe epilepsy surgery: an SEEG study

2021 ◽  
Author(s):  
Cuiping Xu ◽  
Xiaohua Zhang ◽  
Xiaoming Yan ◽  
Kai Ma ◽  
Xueyuan Wang ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Low Voltage ◽  
Discharge Rate ◽  
Low Frequency ◽  
High Amplitude ◽  
Seizure Freedom ◽  
Sharp Waves ◽  
Delta Activity ◽  
Temporal Lobe Resection

Abstract Purpose Seizure originates from different pathological substrate; however, the same pathologies may have distinct mechanisms underlying seizure generation. We aimed to improve the understanding of such mechanisms in patients with temporal lobe epilepsy (TLE) by investigating the stereoelectroencephalography (SEEG) ictal onset patterns (IOPs). Methods We analyzed data from a cohort of 19 consecutive patients explored by SEEG and had 1–3-year seizure-freedom following temporal lobe resection. Results Six IOPs were identified. They were low voltage fast activity (LVFA) (36.5%), rhythmic spikes or spike-waves at low frequency and with high amplitude (34.1%), runs of spikes (10.6%), rhythmic sharp waves (8.2%), low frequency high amplitude repetitive spiking (LFRS) (7.1%), and delta activity (3.5%). All six patterns were found in patients with mesial temporal onset and only two patterns were found in patients with temporal neocortical onset. The most prevalent patterns for patients with mesial temporal onset were rhythmic spikes or spike-waves, followed by LVFA with a mean discharge rate 74 Hz. For patients with temporal neocortical onset, the most prevalent IOP pattern was LVFA with a mean discharge rate 35 Hz, followed by runs of spikes. Compared with Lateral TLE (LTLE), the duration between the onset of the IOPs to the onset of the symptom was longer for patients with MTLE (Mesial TLE) (MTLE:55.7 ± 50.6 s vs LTLE:19.5 ± 16.4 s). Conclusion Multiple IOPs underlie seizure generation in patients with TLE. However, the mesial and lateral temporal lobes share distinct IOPs.

scholarly journals Electroclinical Analysis of Postictal Noserubbing

2000 ◽  
Vol 27 (2) ◽  
pp. 131-136 ◽  
Author(s):  
Richard Wennberg
Keyword(s):  
Temporal Lobe ◽  
Seizure Onset ◽  
Scalp Eeg ◽  
Autonomic Activation ◽  
Ictal Activity ◽  
Primary Generalized Epilepsy ◽  
Generalized Epilepsy ◽  
Temporal Lobe Seizure ◽  
Intracranial Electrodes ◽  
Video Eeg

ABSTRACT:Background:Postictal noserubbing (PIN) has been identified as a good, albeit imperfect, lateralizing and localizing sign in human partial epilepsy, possibly related to ictal autonomic activation.Methods:PIN was studied prospectively in a group of consecutive patients admitted for video-EEG monitoring, with the laterality of noserubbing correlated with electrographic sites of seizure onset, intra- and interhemispheric spread, and sites of seizure termination.Results:PIN was significantly more frequent in temporal than extratemporal epilepsy (p<0.001; 23/41 (56%) patients and 41/197 (21%) seizures in temporal lobe epilepsy compared with 4/34 (12%) patients and 12/167 (7%) seizures in extratemporal epilepsy). The hand used to rub the nose was ipsilateral to the side of seizure onset in 83% of both temporal and extratemporal seizures. Seizures with contralateral PIN correlated with spread to the contralateral temporal lobe on scalp EEG (p<0.04). All extratemporal seizures with PIN showed spread to temporal lobe structures. One patient investigated with intracranial electrodes showed PIN only when ictal activity spread to involve the amygdala: seizures confined to the hippocampus were not associated with PIN. PIN was not observed in 63 nonepileptic events in 17 patients. Unexpectedly, one patient with primary generalized epilepsy showed typical PIN after 1/3 recorded absence seizures.Conclusions:This study confirms PIN as a good indicator of ipsilateral temporal lobe seizure onset. Instances of false lateralization and localization appear to reflect seizure spread to contralateral or ipsilateral temporal lobe structures, respectively. Involvement of the amygdala appears to be of prime importance for induction of PIN.

scholarly journals Three-dimensional hippocampal atrophy maps distinguish two common temporal lobe seizure-onset patterns

Epilepsia ◽  
2009 ◽  
Vol 50 (6) ◽  
pp. 1361-1370 ◽  
Author(s):  
Jennifer A. Ogren ◽  
Anatol Bragin ◽  
Charles L. Wilson ◽  
Gil D. Hoftman ◽  
Jack J. Lin ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Three Dimensional ◽  
Hippocampal Atrophy ◽  
Seizure Onset ◽  
Temporal Lobe Seizure

Do dichotic word listening asymmetries predict side of temporal lobe seizure onset?

1994 ◽  
Vol 19 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Gregory P. Lee ◽  
David W. Loring ◽  
Nils R. Varney ◽  
Richard J. Roberts ◽  
Jason R. Newell ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Seizure Onset ◽  
Temporal Lobe Seizure

Isoflurane Action in the Spinal Cord Blunts Electroencephalographic and Thalamic–Reticular Formation Responses to Noxious Stimulation in Goats

2000 ◽  
Vol 92 (2) ◽  
pp. 559-559 ◽  
Author(s):  
Joseph F. Antognini ◽  
Xiao Wei Wang ◽  
E. Carstens
Keyword(s):  
Spinal Cord ◽  
Reticular Formation ◽  
Low Frequency ◽  
High Amplitude ◽  
Mechanical Stimulus ◽  
Noxious Stimulus ◽  
Noxious Stimulation ◽  
Jugular Veins ◽  
Depth Electrodes ◽  
Beta Power

Background Isoflurane depresses the electroencephalographic (EEG) activity and exerts part of its anesthetic effect in the spinal cord. The authors hypothesized that isoflurane would indirectly depress the EEG and subcortical response to noxious stimulation in part by a spinal cord action. Methods Depth electrodes were inserted into the midbrain reticular formation (MRF) and thalamus of six of seven isoflurane-anesthetized goats, and needle-electrodes were placed into the skull periosteum. In five of seven goats, an MRF microelectrode recorded single-unit activity. The jugular veins and carotid arteries were isolated to permit cranial bypass and differential isoflurane delivery. A noxious mechanical stimulus (1 min) was applied to a forelimb dewclaw at each of two cranial-torso isoflurane combinations: 1.1+/-0.3%-1.2+/-0.3% and 1.1+/-0.3-0.3+/-0.1% (mean +/- SD). Results When cranial-torso isoflurane was 1.1-1.2%, the noxious stimulus did not alter the EEG. When torso isoflurane was decreased to 0.3%, the noxious stimulus activated the MRF, thalamic, and bifrontal-hemispheric regions (decreased high-amplitude, low-frequency power). For all channels combined, total (-33+/-15%), delta(-51+/-22%), theta (-33+/-19%), and alpha (-26+/-16%) power decreased after the noxious stimulus (P&lt;0.05); beta power was unchanged. The MRF unit responses to the noxious stimulus were significantly higher when the spinal cord isoflurane concentration was 0.3% (1,286+/-1,317 impulses/min) as compared with 1.2% (489+/-437 impulses/min, P&lt;0.05). Conclusions Isoflurane blunted the EEG and MRF-thalamic response to noxious stimulation in part via an action in the spinal cord.

scholarly journals Specific imbalance of excitatory/inhibitory signaling establishes seizure onset pattern in temporal lobe epilepsy

2016 ◽  
Vol 115 (6) ◽  
pp. 3229-3237 ◽  
Author(s):  
Massimo Avoli ◽  
Marco de Curtis ◽  
Vadym Gnatkovsky ◽  
Jean Gotman ◽  
Rüdiger Köhling ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Low Voltage ◽  
Mesial Temporal Lobe Epilepsy ◽  
Seizure Onset ◽  
Experimental Conditions ◽  
Eeg Recordings ◽  
Inhibitory Signaling

Low-voltage fast (LVF) and hypersynchronous (HYP) patterns are the seizure-onset patterns most frequently observed in intracranial EEG recordings from mesial temporal lobe epilepsy (MTLE) patients. Both patterns also occur in models of MTLE in vivo and in vitro, and these studies have highlighted the predominant involvement of distinct neuronal network/neurotransmitter receptor signaling in each of them. First, LVF-onset seizures in epileptic rodents can originate from several limbic structures, frequently spread, and are associated with high-frequency oscillations in the ripple band (80–200 Hz), whereas HYP onset seizures initiate in the hippocampus and tend to remain focal with predominant fast ripples (250–500 Hz). Second, in vitro intracellular recordings from principal cells in limbic areas indicate that pharmacologically induced seizure-like discharges with LVF onset are initiated by a synchronous inhibitory event or by a hyperpolarizing inhibitory postsynaptic potential barrage; in contrast, HYP onset is associated with a progressive impairment of inhibition and concomitant unrestrained enhancement of excitation. Finally, in vitro optogenetic experiments show that, under comparable experimental conditions (i.e., 4-aminopyridine application), the initiation of LVF- or HYP-onset seizures depends on the preponderant involvement of interneuronal or principal cell networks, respectively. Overall, these data may provide insight to delineate better therapeutic targets in the treatment of patients presenting with MTLE and, perhaps, with other epileptic disorders as well.

scholarly journals The comparative study of invasive electroencephalography modalities in temporal lobe epilepsy

2021 ◽  
Vol 23 (3) ◽  
pp. 14-22
Author(s):  
V. M. Dzhafarov ◽  
A. B. Dmitriev ◽  
N. P. Denisova ◽  
D. A. Rzaev
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Focal Epilepsy ◽  
Epileptogenic Zone ◽  
Foramen Ovale ◽  
Seizure Onset ◽  
Depth Electrodes ◽  
Seizure Onset Zone ◽  
Temporal Lobe Seizures ◽  
Mesial Temporal Lobe

Introduction. Invasive video-EEG monitoring (invasive EEG) is indicated in patients with refractory focal epilepsy while localization of the epileptogenic zone is unclear. Methods of invasive EEG in different groups of patients demonstrate variable results.Objective: to analyse the results of invasive EEG via subdural and depth electrodes in patients with refractory temporal lobe epilepsy with mesial temporal lobe seizures.Materials and methods. The series of 37 patients who underwent invasive EEG from 2013 to 2020 was retrospectively analysed. The study includes primary adult patients with structural refractory focal epilepsy with mesial temporal lobe seizures without tumor and vascular pathology. Patients were divided onto 3 groups: 1) with foramen ovale electrodes 2) subdural strip electrodes and 3) combination of subdural strips and depths electrodes. The results of anteromedial temporal lobectomy after 6 months were classified according to Engel scale.Results. A group with foramen ovale electrodes included 7 patients, subdural strips – 23, combination – 7. The seizure onset zone was detected in 36 (97 %) cases. Serious complications were observed in 2 (29 %) cases in the group with foramen ovale electrodes. The mean follow-up in 23 (76 %) patients after resective surgery was 28.3 months. Favourable results (Engel I, II) were observed in 4 (80 %) patients with foramen ovale electrodes, in 8 (67 %) patients with subdural electrodes, in 6 (100 %) with combination. Unfavourable results (Engel III, IV) were noted in 1 (20 %) patient with foramen ovale electrode, in 4 (33 %) patients with subdural strips.Conclusion. All the presented modalities of invasive EEG are effective for localizing of seizure onset zone in this category of patients. Foramen ovale electrode using may be limited due to increased risk of complications.

scholarly journals Role of the temporal pole in temporal lobe epilepsy seizure networks: an intracranial electrode investigation

2018 ◽  
Vol 129 (1) ◽  
pp. 165-173 ◽  
Author(s):  
Taylor J. Abel ◽  
Royce W. Woodroffe ◽  
Kirill V. Nourski ◽  
Toshio Moritani ◽  
Aristides A. Capizzano ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Epileptogenic Zone ◽  
Invasive Monitoring ◽  
Seizure Onset ◽  
Temporal Pole ◽  
Interictal Discharges ◽  
Temporal Lobe Seizure ◽  
Clinical Records

OBJECTIVEA convergence of clinical research suggests that the temporal pole (TP) plays an important and potentially underappreciated role in the genesis and propagation of seizures in temporal lobe epilepsy (TLE). Understanding its role is becoming increasingly important because selective resections for medically intractable TLE spare temporopolar cortex (TPC). The purpose of this study was to characterize the role of the TPC in TLE after using dense electrocorticography (ECoG) recordings in patients undergoing invasive monitoring for medically intractable TLE.METHODSChronic ECoG recordings were obtained in 10 consecutive patients by using an array customized to provide dense coverage of the TP as part of invasive monitoring to localize the epileptogenic zone. All patients would eventually undergo cortico-amygdalohippocampectomy. A retrospective review of the patient clinical records including ECoG recordings, neuroimaging studies, neuropathology reports, and clinical outcomes was performed.RESULTSIn 7 patients (70%), the TP was involved at seizure onset; in 7 patients (70%), there were interictal discharges from the TP; and in 1 case, there was early spread to the TP. Seizure onset in the TP did not necessarily correlate with preoperative neuroimaging abnormalities of the TP.CONCLUSIONSThese data demonstrate that TPC commonly plays a crucial role in temporal lobe seizure networks. Seizure onset from the TP would not have been predicted based on available neuroimaging data or interictal discharges. These findings illustrate the importance of thoroughly considering the role of the TP prior to resective surgery for TLE, particularly when selective mesial resection is being considered.

scholarly journals Robotic Orthogonal Implantation of Responsive Neurostimulation (RNS) Depth Electrodes in Patients With Unilateral Mesial Temporal Lobe Seizure Onset

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Alvin Y Chan ◽  
Sumeet Vadera
Keyword(s):  
Temporal Lobe ◽  
Disease Onset ◽  
Electrode Placement ◽  
Neutral Position ◽  
Initial Experience ◽  
Depth Electrodes ◽  
Number Of Patients ◽  
Multiple Variables ◽  
Mesial Temporal Lobe

Abstract INTRODUCTION Responsive neurostimulation (RNS) is a closed-loop neurostimulation modality for treating intractable epilepsy in patients who are not candidates for resection. A high number of patients have ictal onsets originating in the temporal lobe. In the past, implantation of depth electrodes have been placed using a transoccipital approach that transverses the long axis of the hippocampus. However, there have been no description of orthogonal approaches to RNS electrode placement into the medial temporal structures in the literature. We aimed to describe our initial experience with placing RNS depth electrodes using an orthogonal approach to target the short axis of the mesial temporal lobe. METHODS Presurgical work up included magnetic resonance imaging (MRI), video electroencephalography (vEEG), and neuropsychological testing. During the procedure, patients were placed with their heads in a neutral position. Electrodes were placed via stereotactic robotic assistance using a unilateral orthogonal approach targeting the amygdala or hippocampus. Patients who underwent RNS electrode implantation via orthogonal approach were identified after a retrospective review of all RNS patients at our institution. Multiple variables were collected, including age, disease onset, complications, follow-up, semiology, and seizure reduction. RESULTS There were 4 patients who underwent RNS implantation with orthogonal electrode placement. The mean age and follow-up were 44.8 and 1.2 yr, respectively. One of 8 patients was seizure free at last follow-up and 2 experienced over 50% reduction in seizures. There was one surgical complication but no mortality. CONCLUSION The initial experience using an orthogonal approach for depth electrode placement for RNS implantation was described. The potential advantages may include better safety, accuracy, and positioning in comparison to a transoccipital approach. Limitations included the retrospective nature of the study and a low sample size. Further research and experience are required to determine the best indications for an orthogonal approach.

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