scholarly journals Electroencephalographic Features of Temporal Lobe Epilepsy

2010 ◽  
Vol 37 (4) ◽  
pp. 439-448 ◽  
Author(s):  
Mohammed M. Jan ◽  
Mark Sadler ◽  
Susan R. Rahey
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Surgical Management ◽  
Temporal Lobe ◽  
Seizure Onset ◽  
Resective Surgery ◽  
Accurate Localization ◽  
Epileptiform Discharges ◽  
Ictal Eeg ◽  
Temporal Lobe Seizures ◽  
Eeg Recordings

Electroencephalography (EEG) is an important tool for diagnosing, lateralizing and localizing temporal lobe seizures. In this paper, we review the EEG characteristics of temporal lobe epilepsy (TLE). Several “non-standard” electrodes may be needed to further evaluate the EEG localization, Ictal EEG recording is a major component of preoperative protocols for surgical consideration. Various ictal rhythms have been described including background attenuation, start-stop-start phenomenon, irregular 2-5 Hz lateralized activity, and 5-10 Hz sinusoidal waves or repetitive epileptiform discharges. The postictal EEG can also provide valuable lateralizing information. Postictal delta can be lateralized in 60% of patients with TLE and is concordant with the side of seizure onset in most patients. When patients are being considered for resective surgery, invasive EEG recordings may be needed. Accurate localization of the seizure onset in these patients is required for successful surgical management.

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 D.05 SREDA-like temporal EEG seizure pattern in LGI1-antibody mediated encephalitis

2016 ◽  
Vol 43 (S2) ◽  
pp. S14-S14
Author(s):  
C Steriade ◽  
S Mirsattari ◽  
BJ Murray ◽  
R Wennberg
Keyword(s):  
Clinical Features ◽  
Temporal Lobe ◽  
Limbic Encephalitis ◽  
Cognitive Symptoms ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges ◽  
Eeg Abnormalities ◽  
Eeg Data ◽  
Temporal Lobe Seizures ◽  
Eeg Recordings

Background: Leucine-rich glioma inactived-1 (LGI1) antibodies are associated with limbic encephalitis and distinctive seizure types, which are typically immunotherapy-responsive. While nonspecific EEG abnormalities are commonly seen, specific EEG characteristics are not currently understood to be useful for suspecting the clinical diagnosis. Based on initial observations in two patients, we analyzed the EEG recordings in a larger series of patients and describe a novel ictal pattern that can suggest the diagnosis of LGI1-antibody mediated encephalitis, even in the absence of common clinical features. Methods: Clinical and EEG data were collected in nine patients with LGI1 antibodies. Results: Psychiatric and cognitive symptoms were common, as were tonic seizures associated with EEG electrodecremental events (often with the so-called faciobrachial dystonic semiology). A rarity or absence of interictal epileptiform discharges contrasted with frequent subclinical temporal lobe seizures in some patients, which at times showed characteristics similar to subclinical rhythmic electrographic discharges of adults (SREDA), including sensitivity to hyperventilation. Conclusions: LGI1-antibody mediated encephalitis may be associated with tonic seizures and corresponding electrodecremental events, as well as an unusual SREDA-like pattern of frequent subclinical temporal lobe seizures, which may be triggered by hyperventilation, all in the setting of rare interictal epileptiform discharges.

Source Localization of Temporal Lobe Epilepsy Using PCA—LORETA Analysis on Ictal EEG Recordings

2009 ◽  
Vol 26 (2) ◽  
pp. 109-116 ◽  
Author(s):  
Yaki Stern ◽  
Miriam Y. Neufeld ◽  
Svetlana Kipervasser ◽  
Amir Zilberstein ◽  
Itzhak Fried ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Source Localization ◽  
Ictal Eeg ◽  
Eeg Recordings

scholarly journals Preoperative Electroencephalographic Investigation in Temporal Lobe Epilepsy: Extracranial and Intracranial Recordings

1991 ◽  
Vol 18 (S4) ◽  
pp. 554-558 ◽  
Author(s):  
Pierre Gloor
Keyword(s):  
Temporal Lobe ◽  
Video Monitoring ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges ◽  
Eeg Data ◽  
Temporal Lobe Seizures ◽  
Eeg Recordings ◽  
Intracranial Recordings ◽  
Eeg Features

ABSTRACT:Preoperative EEG investigations of patients with temporal lobe seizures include extracranial interictal and ictal recordings during wakefulness and sleep, including long-term EEG and video-monitoring. Interictal epileptiform discharges when evaluated conservatively and in conjunction with other EEG and non-EEG localizing information, provide valuable guidance for the identification of the area to be resected, as do ictal recordings. When extracranial EEG features in conjunction with non-EEG data provide conflicting localizing information, intracranial recordings with stereotaxically implanted depth and epidural electrodes are used. Intracranial recordings must be designed to avoid biasing the exploration strategy in favor of one's preferred localizing hypothesis. Patients with evidence for bitemporal epileptogenic dysfunction in extracranial EEG recordings are suitable candidates for intracranial recordings. The majority of the patients explored in this manner show that all or more than 80% of their seizures arise from one temporal lobe. Excision of that lobe yields satisfactory results in a fair proportion of these patients. The number of satisfactory outcomes is, however, still somewhat less than in patients with unilateral temporal foci in extracranial EEG recordings.

scholarly journals Utility of invasive ictal EEG recordings in pre-surgical evaluation of patients with medically refractory temporal lobe epilepsy and normal MRI

2015 ◽  
Vol 02 (02) ◽  
pp. 066-071 ◽  
Author(s):  
Jeffrey Chung ◽  
Kimford Meador ◽  
Stephan Eisenschenk ◽  
Georges Ghacibeh ◽  
Deborah Vergara ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Primary Outcome ◽  
Surgical Decision ◽  
Additional Information ◽  
Ictal Eeg ◽  
Surgical Evaluation ◽  
Eeg Recordings ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain

AbstractPurpose Some previous studies have suggested that invasive ictal recording may be omitted in patients with medically refractory temporal lobe epilepsy (TLE) that have localizing scalp ictal recordings despite having normal magnetic resonance imaging (MRI). We investigated if and how often invasive ictal recording provided additional information to their pre-surgical evaluations.Methods In a retrospective review of 302 patients with intractable TLE who underwent pre-surgical evaluation between 1991 and 2006, we identified 45 patients who had normal MRI. Localization by scalp ictal recording, invasive ictal recording, and surgical procedures were obtained from medical records. Primary outcome was measured by comparing the concordance of localization by scalp and invasive ictal recordings and surgery to determine if invasive ictal recording provided additional information.Results Twenty-five patients were included in the analysis. Invasive ictal recordings were concordant in 72.0% (18/25) of the patients with unilateral temporal onset found on scalp ictal recording. 28.0% (7/25) of patients had their surgical plan altered by the results of invasive ictal recording. 61.1% (11/18) of patients who received anterior temporal lobectomies (ATL) remained seizure-free. Of the patients who received different surgeries based on invasive ictal recording, 80.0% (4/5) remained seizure-free.Conclusions Our study showed that findings from invasive ictal recording changed the type of surgery in 28.0% of the patients. Invasive ictal recording may not be an absolute prerequisite for resective epilepsy surgery in some patients with intractable TLE with a supposedly normal MRI of the brain but may alter the surgical decision.

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