History and seizure semiology in distinguishing frontal lobe seizures and temporal lobe seizures

Value of semiology in predicting epileptogenic zone and surgical outcome following frontal lobe epilepsy surgery

OBJECTIVE

To evaluate the ability of semiology alone in localising the epileptogenic zone (EZ) in people with frontal lobe epilepsy (FLE) who underwent resective surgery.

METHODS

We examined data on all individuals who had FLE surgery at our centre between January 01, 2011 and December 31, 2020. Descriptions of ictal semiology were obtained from video-EEG telemetry reports and presurgical multidisciplinary meeting summaries. The putative EZ was represented by the final site of resection. We assessed how well initial and combined set-of-semiologies correlated anatomically with the EZ, using a semiology visualisation tool to generate probabilistic cortical heatmaps of involvement in seizures.

RESULTS

Sixty-one individuals had FLE surgery over the study period. Twelve months following surgery, 28/61 (46%) were completely seizure-free, with a further eight experiencing only auras. Comparing the semiology database with the putative EZ, combined set-of-semiology correctly lateralised in 77% (95% CI: 69-85%), localised to the frontal lobe in 57% (95% CI: 48-67%), frontal lobe subregions in 52% (95% CI: 43-62%), and frontal gyri in 25% (95% CI: 16-33%). No difference in degree of correlation was seen comparing those with ongoing seizures 12 months after surgery to those seizure free.

SIGNIFICANCE

Semiology alone was able to correctly lateralize the putative EZ in 77%, and localise to a sublobar level in approximately half of individuals who had FLE surgery. Semiology is not adequate alone and must be combined with imaging and EEG data to identify the epileptogenic zone.

Correlation Between Ictal Signs and Anatomical Subgroups in Temporal Lobe Seizures: A Stereoelectroencephalography Study

Objective

Ictal semiology is a fundamental part of the presurgical evaluation of patients with temporal lobe epilepsy. We aimed to identify different anatomical and semiologic subgroups in temporal lobe seizures, and investigate the correlation between them.

Methods

We enrolled 93 patients for whom stereoelectroencephalography exploration indicated that the seizure-onset zone was within the temporal lobe. Ictal signs and concomitant stereoelectroencephalography changes were carefully reviewed and quantified, and then cluster analysis and the Kendall correlation test were used to associate ictal signs with the temporal structures of patients.

Results

Clustering analysis identified two main groups of temporal structures. Group 1 consisted of the medial temporal lobe structures and the temporal pole, which were divided into two subgroups. Group 1A included the hippocampal head, hippocampal body, and amygdala, and this subgroup correlated significantly with oroalimentary automatisms, feeling of fear, and epigastric auras. Group 1B included the hippocampal tail, temporal pole, and parahippocampal gyrus, and this subgroup correlated significantly with manual and oroalimentary automatisms. Group 2 consisted of the cortical structures of the temporal lobe and was also divided into two subgroups. Group 2A included the superior and middle temporal gyrus, correlated significantly with bilateral rictus/facial contraction, generalized tonic-clonic seizure, and manual automatisms. Group 2B included Heschl's gyrus, the inferior temporal gyrus, and the fusiform gyrus, and this subgroup correlated significantly with auditory auras, focal hypokinetics, unilateral upper and lower limbs tonic posture/clonic signs, head/eye deviation, unilateral versive signs, and generalized tonic-clonic seizure.

Significance

The temporal structures can be categorized according to the level at which each structure participates in seizures, and different anatomical subgroups can be correlated with different ictal signs. Identifying specific semiologic features can help us localize the epileptogenic zone and thus develop stereoelectroencephalography electrode implantation and surgical resection protocols for patients with temporal lobe epilepsy.

Comparing Ictal Cardiac Autonomic Changes in Patients with Frontal Lobe Epilepsy and Temporal Lobe Epilepsy by Ultra-Short-Term Heart Rate Variability Analysis

Background and Objectives: Abnormal epileptic discharges in the brain can affect the central brain regions that regulate autonomic activity and produce cardiac symptoms, either at onset or during propagation of a seizure. These autonomic alterations are related to cardiorespiratory disturbances, such as sudden unexpected death in epilepsy. This study aims to investigate the differences in cardiac autonomic function between patients with temporal lobe epilepsy (TLE) and frontal lobe epilepsy (FLE) using ultra-short-term heart rate variability (HRV) analysis around seizures. Materials and Methods: We analyzed electrocardiogram (ECG) data recorded during 309 seizures in 58 patients with epilepsy. Twelve patients with FLE and 46 patients with TLE were included in this study. We extracted the HRV parameters from the ECG signal before, during and after the ictal interval with ultra-short-term HRV analysis. We statistically compared the HRV parameters using an independent t-test in each interval to compare the differences between groups, and repeated measures analysis of variance was used to test the group differences in longitudinal changes in the HRV parameters. We performed the Tukey-Kramer multiple comparisons procedure as the post hoc test. Results: Among the HRV parameters, the mean interval between heartbeats (RRi), normalized low-frequency band power (LF) and LF/HF ratio were statistically different between the interval and epilepsy types in the t-test. Repeated measures ANOVA showed that the mean RRi and RMSSD were significantly different by epilepsy type, and the normalized LF and LF/HF ratio significantly interacted with the epilepsy type and interval. Conclusions: During the pre-ictal interval, TLE patients showed an elevation in sympathetic activity, while the FLE patients showed an apparent increase and decrease in sympathetic activity when entering and ending the ictal period, respectively. The TLE patients showed a maintained elevation of sympathetic and vagal activity in the pos-ictal interval. These differences in autonomic cardiac characteristics between FLE and TLE might be relevant to the ictal symptoms which eventually result in SUDEP.

Can semiology differentiate between bilateral tonic-clonic seizures of focal-onset and generalized-onset? A systematic review

OBJECTIVE

Bilateral tonic-clonic seizures are encountered in both focal and generalized epilepsies. We reviewed the literature regarding the presence of focal signs in generalized-onset tonic-clonic seizures (GOTCS) and the utility of semiology in differentiating those from focal to bilateral tonic-clonic seizures (FBTCS).

METHODS

We conducted a comprehensive literature search using four electronic databases (Medline, Embase, Web of Science, and Psychinfo) and constructed a systematic review in keeping with the Preferred Items for Systematic Reviews and Meta-analyses guidelines.

RESULTS

We included 13 studies on focal semiological features of GOTCS. These studies included a total of 952 participants. The key focal signs described in GOTCS included: early head version, figure of four sign, asymmetric seizure termination, and a multitude of auras as well as automatisms. Additionally, we reviewed five studies that investigated the use of semiology to differentiate GOTCS from FBTCS; these studies had a total of 289 participants. Asymmetry in clonic phase, side-to-side axial movements, asymmetrical seizure termination, figure of four sign, index finger pointing, and fanning posture of the hand were found to be significantly more frequent in FBTCS compared with GOTCS. Furthermore, combinations of focal semiological features occurring in a single seizure were found to be suggestive of FBTCS rather than GOTCS.

CONCLUSION

Focal signs are often evident in GOTCS. Though the observation of multiple focal signs within a given seizure may be in favor of an FBTCS, our findings caution against differentiating between the two seizure types based on semiology alone due to considerable overlap in focal features.

EEG for children with complex febrile seizures

BACKGROUND

Febrile seizures can be classified as simple or complex. Complex febrile seizures are associated with fever that lasts longer than 15 minutes, occur more than once within 24 hours, and are confined to one side of the child's body. It is common in some countries for doctors to recommend an electroencephalograph (EEG) for children with complex febrile seizures. A limited evidence base is available to support the use of EEG and its timing after complex febrile seizures among children.

OBJECTIVES

To assess the use of EEG and its timing after complex febrile seizures in children younger than five years of age.

SEARCH METHODS

For the latest update of this review, we searched the following databases on 12 March 2019: Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE (Ovid, 1946 to 11 March 2019); and ClinicalTrials.gov. We applied no language restrictions.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that examined the utility of an EEG and its timing after complex febrile seizures in children.

DATA COLLECTION AND ANALYSIS

The review authors selected and retrieved the articles and independently assessed which articles should be included. Any disagreements were resolved by discussion and by consultation with the Cochrane Epilepsy Group. We applied standard methodological procedures expected by Cochrane.

MAIN RESULTS

Of 48 potentially eligible studies, no RCTs met the inclusion criteria.

AUTHORS' CONCLUSIONS

We found no RCTs as evidence to support or refute the use of EEG and its timing after complex febrile seizures among children under the age of five. An RCT can be planned in such a way that participants are randomly assigned to the EEG group and to the non-EEG group with sufficient sample size. Since the last version of this review, we have found no new studies.

EEG for children with complex febrile seizures

BACKGROUND

Febrile seizures can be classified as simple or complex. Complex febrile seizures are associated with fever that lasts longer than 15 minutes, occur more than once within 24 hours, and are confined to one side of the child's body. It is common in some countries for doctors to recommend an electroencephalograph (EEG) for children with complex febrile seizures. A limited evidence base is available to support the use of EEG and its timing after complex febrile seizures among children.

OBJECTIVES

To assess the use of EEG and its timing after complex febrile seizures in children younger than five years of age.

SEARCH METHODS

For the latest update of this review, we searched the Cochrane Epilepsy Group Specialized Register (23 January 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online (CRSO, 23 January 2017), MEDLINE (Ovid, 23 January 2017), and ClinicalTrials.gov (23 January 2017). We applied no language restrictions.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that examined the utility of an EEG and its timing after complex febrile seizures in children.

DATA COLLECTION AND ANALYSIS

The review authors selected and retrieved the articles and independently assessed which articles should be included. Any disagreements were resolved by discussion and by consultation with the Cochrane Epilepsy Group. We applied standard methodological procedures expected by Cochrane.

MAIN RESULTS

Of 41 potentially eligible studies, no RCTs met the inclusion criteria.

AUTHORS' CONCLUSIONS

We found no RCTs as evidence to support or refute the use of EEG and its timing after complex febrile seizures among children. An RCT can be planned in such a way that participants are randomly assigned to the EEG group and to the non-EEG group with sufficient sample size. Since the last version of this review, we have found no new studies.

EEG for children with complex febrile seizures

BACKGROUND

This is an updated version of original Cochrane review published in Issue 1, 2014.Febrile seizures can be classified as simple or complex. Complex febrile seizures are associated with fever that lasts longer than 15 minutes, occur more than once within 24 hours and are confined to one side of the child's body. It is common in some countries for doctors to recommend an electroencephalograph (EEG) for children with complex febrile seizures. A limited evidence base is available to support the use of EEG and its timing after complex febrile seizures among children.

OBJECTIVES

To assess the use of EEG and its timing after complex febrile seizures in children younger than five years of age.

SEARCH METHODS

For the latest update of this review, we searched the Cochrane Epilepsy Group Specialized Register (6 July 2015), the Cochrane Central Register of Controlled Trials (CENTRAL, 2005, Issue 6), MEDLINE (6 July 2015) and ClinicalTrials.gov (6 July 2015). We applied no language restrictions.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that examined the utility of an EEG and its timing after complex febrile seizures in children.

DATA COLLECTION AND ANALYSIS

Review authors selected and retrieved the articles and independently assessed which articles should be included. We resolved disagreements by discussion and by consultation with the Cochrane Epilepsy Group. We applied standard methodological procedures expected by Cochrane.

MAIN RESULTS

Of 37 potentially eligible studies, no RCTs met the inclusion criteria.

AUTHORS' CONCLUSIONS

We found no RCTs as evidence to support or refute the use of EEG and its timing after complex febrile seizures among children. An RCT can be planned in such a way that participants are randomly assigned to the EEG group and to the non-EEG group with sufficient sample size. Since the last version of this review, we found no new studies.

Emergence of semiology in epileptic seizures

Semiology, the manifestation of epilepsy, is dependent upon electrical activity produced by epileptic seizures that are organized within existing neural pathways. Clinical signs evolve as the epileptic discharge spreads in both time and space. Studying the relation between these, of which the temporal component is at least as important as the spatial one, is possible using anatomo-electro-clinical correlations of stereoelectroencephalography (SEEG) data. The period of semiology production occurs with variable time lag after seizure onset and signs then emerge more or less rapidly depending on seizure type (temporal seizures generally propagating more slowly and frontal seizures more quickly). The subset of structures involved in semiological production, the "early spread network", is tightly linked to those constituting the epileptogenic zone. The level of complexity of semiological features varies according to the degree of involvement of the primary or associative cortex, with the former having a direct relation to peripheral sensory and motor systems with production of hallucinations (visual and auditory) or elementary sensorimotor signs. Depending on propagation pattern, these signs can occur in a "march" fashion as described by Jackson. On the other hand, seizures involving the associative cortex, having a less direct relation with the peripheral nervous system, and necessarily involving more widely distributed networks manifest with altered cognitive and/or behavioral signs whose neural substrate involves a network of cortical structures, as has been observed for normal cognitive processes. Other than the anatomical localization of these structures, the frequency of the discharge is a crucial determinant of semiological effect since a fast (gamma) discharge will tend to deactivate normal function, whereas a slower theta discharge can mimic physiological function. In terms of interaction between structures, the degree of synchronization plays a key role in clinical expression, as evidenced, for example, by studies of ictal fear-related behavior (decorrelation of activity between structures inducing "release" phenomena) and of déjà vu (increased synchronization). Studies of functional coupling within networks underlying complex ictal behavior indicate that the clinical semiology of a given seizure depends upon neither the anatomical origin of ictal discharge nor the target areas of its propagation alone but on the dynamic interaction between these. Careful mapping of the ictal network in its full spread offers essential information as to the localization of seizure onset, by deducing that a given network configuration could only be generated by a given area or group of areas.

Neural network underlying ictal pouting ("chapeau de gendarme") in frontal lobe epilepsy

In order to determine the anatomical neural network underlying ictal pouting (IP), with the mouth turned down like a "chapeau de gendarme", in frontal lobe epilepsy (FLE), we reviewed the video-EEG recordings of 36 patients with FLE who became seizure-free after surgery. We selected the cases presenting IP, defined as a symmetrical and sustained (>5s) lowering of labial commissures with contraction of chin, mimicking an expression of fear, disgust, or menace. Ictal pouting was identified in 11 patients (8 males; 16-48 years old). We analyzed the clinical semiology, imaging, and electrophysiological data associated with IP, including FDG-PET in 10 and SEEG in 9 cases. In 37 analyzed seizures (2-7/patient), IP was an early symptom, occurring during the first 10s in 9 cases. The main associated features consisted of fear, anguish, vegetative disturbances, behavioral disorders (sudden agitation, insults, and fighting), tonic posturing, and complex motor activities. The epileptogenic zone assessed by SEEG involved the mesial frontal areas, especially the anterior cingulate cortex (ACC) in 8 patients, whereas lateral frontal onset with an early spread to the ACC was seen in the other patient. Ictal pouting associated with emotional changes and hypermotor behavior had high localizing value for rostroventral "affective" ACC, whereas less intense facial expressions were related to the dorsal "cognitive" ACC. Fluorodeoxyglucose positron emission tomography demonstrated the involvement of both the ACC and lateral cortex including the anterior insula in all cases. We propose that IP is sustained by reciprocal mesial and lateral frontal interactions involved in emotional and cognitive processes, in which the ACC plays a pivotal role.

Finger snapping during seizures

We describe two patients who showed snapping of the right hand fingers during invasive intracranial EEG evaluation for epilepsy surgery. We correlated the EEG changes with the finger-snapping movements in both patients to determine the underlying pathophysiology of this phenomenon. At the time of finger snapping, EEG spread from the supplementary motor area towards the temporal region was seen, suggesting involvement of these sites.

EEG for children with complex febrile seizures

BACKGROUND

Febrile seizures can be classified as simple or complex. Complex febrile seizures are associated with fever that lasts longer than 15 minutes, occur more than once within 24 hours and are confined to one side of the child's body. It is common in some countries for doctors to recommend an electroencephalograph (EEG) for children with complex febrile seizures. A limited evidence base is available to support the use of EEG and its timing after complex febrile seizures among children.

OBJECTIVES

To assess the use of EEG and its timing after complex febrile seizures in children younger than five years of age.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialised Register (17 October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 9, 2013), MEDLINE (17 October 2013) and the Clinical Trial Registry (ClinicalTrials.gov (17 October 2013)). We applied no language restrictions.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that examined the utility of an EEG and its timing after complex febrile seizures in children.

DATA COLLECTION AND ANALYSIS

Review authors selected and retrieved the articles and independently assessed which articles should be included. Disagreements were resolved by discussion and by consultation with the Cochrane Epilepsy Group. We applied standard methodological procedures expected by The Cochrane Colloboration.

MAIN RESULTS

Of 33 potentially eligible studies, no RCTs met the inclusion criteria.

AUTHORS' CONCLUSIONS

We found no RCTs as evidence to support or refute the use of EEG and its timing after complex febrile seizures among children. A randomised controlled trial can be planned in such a way that participants are randomly assigned to the EEG group and to the non-EEG group with sufficient sample size.

Seizure semiology: its value and limitations in localizing the epileptogenic zone

Epilepsy surgery has become an important treatment option in patients with medically refractory epilepsy. The ability to precisely localize the epileptogenic zone is crucial for surgical success. The tools available for localization of the epileptogenic zone are limited. Seizure semiology is a simple and cost effective tool that allows localization of the symptomatogenic zone which either overlaps or is in close proximity of the epileptogenic zone. This becomes particularly important in cases of MRI negative focal epilepsy. The ability to video record seizures made it possible to discover new localizing signs and quantify the sensitivity and specificity of others. Ideally the signs used for localization should fulfill these criteria; 1) Easy to identify and have a high inter-rater reliability, 2) It has to be the first or one of the earlier components of the seizure in order to have localizing value. Later symptoms or signs are more likely to be due to ictal spread and may have only a lateralizing value. 3) The symptomatogenic zone corresponding to the recorded ictal symptom has to be clearly defined and well documented. Reproducibility of the initial ictal symptoms with cortical stimulation identifies the corresponding symptomatogenic zone. Unfortunately, however, not all ictal symptoms can be reproduced by focal cortical stimulation. Therefore, the problem the clinician faces is trying to deduce the epileptogenic zone from the seizure semiology. The semiological classification system is particularly useful in this regard. We present the known localizing and lateralizing signs based on this system.

Temporal lobe epilepsy semiology

Epilepsy represents a multifaceted group of disorders divided into two broad categories, partial and generalized, based on the seizure onset zone. The identification of the neuroanatomic site of seizure onset depends on delineation of seizure semiology by a careful history together with video-EEG, and a variety of neuroimaging technologies such as MRI, fMRI, FDG-PET, MEG, or invasive intracranial EEG recording. Temporal lobe epilepsy (TLE) is the commonest form of focal epilepsy and represents almost 2/3 of cases of intractable epilepsy managed surgically. A history of febrile seizures (especially complex febrile seizures) is common in TLE and is frequently associated with mesial temporal sclerosis (the commonest form of TLE). Seizure auras occur in many TLE patients and often exhibit features that are relatively specific for TLE but few are of lateralizing value. Automatisms, however, often have lateralizing significance. Careful study of seizure semiology remains invaluable in addressing the search for the seizure onset zone.

Hyperkinetic seizures in patients with temporal lobe epilepsy: clinical features and outcome after temporal lobe resection

PURPOSE

Temporal lobe epilepsy (TLE) is usually associated with automatisms. Hyperkinetic seizures are supposed to be unusual. Because we witnessed several patients with TLE and ictal hyperkinetic symptoms, we retrospectively assessed the number, clinical findings, and seizure outcome in such patients who had undergone temporal lobe resection.

METHODS

We reviewed medical history, video-electroencephalography (EEG) recording and neuroimaging of adult patients who underwent epilepsy surgery for TLE at the Kork Epilepsy Center over the last 20 years with a minimum postoperative follow-up of 12 months.

KEY FINDINGS

Among 294 patients who were resected exclusively in the temporal region, we identified 17 (6%) who presented with hyperkinetic semiology such as violent vocalization, complex movements of the proximal segments of the limbs, rotation of the trunk, pelvic thrusting, or early tonic or dystonic posturing. Most of the patients had a preceding aura. Ictal EEG activity was located in the corresponding temporal region, usually with a wide distribution over temporal electrodes with fast spread to unilateral frontal electrodes and to the contralateral side. Neuroimaging revealed extended lesions in the temporal lobe involving mesial and neocortical structures. Most of the patients underwent classical anterior temporal lobe resection including amygdalo-hippocampectomy. Fourteen patients (82%) became completely seizure-free (Engel class Ia). Histopathology showed mainly focal cortical dysplasia plus hippocampal sclerosis.

SIGNIFICANCE

Hyperkinetic seizure semiology may occasionally occur in patients with TLE and is, therefore, no contradiction to the hypothesis of TLE if scalp EEG patterns and neuroimaging findings correspond. The postoperative seizure outcome is favorable in such patients and not different from outcome data in classical TLE.

Fyodor Dostoevsky and his falling sickness: a critical analysis of seizure semiology

Fyodor Dostoevsky is a great Russian writer who had epilepsy. As a consequence, there are many references to seizure-related phenomena in his work. His epilepsy syndrome has been a focus of debate. The goal of this article is to delineate his epilepsy syndrome based on a semiological description of seizures, which could be considered one of the most reliable pieces of circumstantial evidence available. It was hypothesized that seizure-related descriptions in his books were based on his own personal experience. The semiology of seizures and related phenomena was compiled from Dostoevsky's own work, his letters to family and friends, and reminiscences of his wife and friend. Those descriptions were analyzed in detail to elicit localizing and lateralizing features of seizures. On the basis of this evidence, it was postulated that Dostoevsky had a partial epilepsy syndrome most probably arising from the dominant temporal lobe.