Significance of Simple Partial Seizures in Temporal Lobe Epilepsy

Summary: We determined how localization of simple partial seizures (SPS) correlated with localization of complex partial seizure (CPS) in scalp/sphenoidal EEG and assessed prognosis after temporal lobe resective surgery in patients with an ictal correlate of SPS in scalp/sphenoidal EEG recordings. EEGs were recorded with the 10–20 system of electrode placement and supplemented with sphenoidal electrodes. Between 1985 and 1992, 183 patients with temporal lobe epilepsy (TLE) reported an aura (SPS) during inpatient monitoring; all were eligible for inclusion in our study. The EEGs during SPS showed ictal changes in 51 patients (28%, 117 SPS). Forty-four patients had unilateral temporal interictal spikes (IIS), and SPS and CPS always arose from the same region. Seven patients had bitemporal interictal spikes; SPS colocalized with CPS in 4 patients (57%), SPS were contralateral to CPS in 2 patients, and 1 patient had bilateral independent CPS but unilateral SPS. SPS accompanied by EEG ictal changes conveyed a favorable prognosis in patients who underwent epilepsy surgery. Scalp/sphenoidal recorded IIS but were less reliable in identifying the location of CPS onset in patients with bitemporal spikes.     

Patients' ability to react before complex partial seizures

ObjectiveThe purpose of the study described here was to investigate the pathophysiology of patients’ ability to react during the conscious (aura) phase of complex partial seizures (CPS) originating from the temporal lobe.MethodsWe reviewed video recordings of CPS experienced by 130 adult patients who had undergone epilepsy surgery for intractable medial temporal lobe epilepsy. All patients were instructed to push the alarm button when they felt an aura. We defined the preictal reactivity as the ability to push the alarm button before the complex partial (unconscious) phase of seizures.ResultsSeventy-seven patients (59%) pushed the alarm button before seizures. Patients with preictal reactivity were significantly younger, more often had lateralized EEG seizure patterns, and had a better postoperative outcome. Patients who did not push the alarm button had secondarily generalized seizures more often.ConclusionsAbility to react before CPS is associated with a circumscribed region involved at seizure onset and spread, and with a seizure-free postoperative outcome.     

Characteristics and clinical significance of subclinical seizures

Purpose: To define characteristics of subclinical seizures (SCS) and their prognostic significance after epilepsy surgery. Methods: Reports from intracranial video‐EEG monitoring were reviewed for patients who had epilepsy surgery between 1989 and 2003. Relationships between SCS and clinical seizures were categorized as either: complete colocalization (Group A), when both SCS and clinical seizures originated from the same single focus, or incomplete and no colocalization (Group B), when some or all SCS and clinical seizures originated from different foci in different lobes or hemispheres. Results: A total of 111 patients were included in this review. Seventy‐one (64%) patients had 2,821 SCS and most SCS came from the mesial temporal lobe. The mean duration of SCS was shorter than complex partial seizures and generalized tonic–clonic seizures but similar to simple partial seizures. SCS rarely propagated beyond the site of origin and the majority of SCS had the same area of origin as clinical seizures. Sixty‐five patients had both SCS and clinical seizures and underwent resective surgery. Group A patients had a higher seizure‐free outcome rate (77.5%) than Group B patients (37.5%). The colocalization rate of SCS and clinical seizures may impact seizure‐free outcome. The presence or absence of SCS, SCS duration, and extent of propagation of SCS did not influence surgical outcome. Conclusion: SCS commonly originate from the same cortical area as clinical seizures and are related to postsurgical outcome. These findings suggest they should be viewed as having similar significance in the surgical decision process as clinical seizures.     

Characteristics of intractable seizures following meningitis and encephalitis.

We studied clinical seizure characteristics, seizure localization, and pathology in 38 patients who developed medically intractable partial seizures following meningitis (n = 16) or encephalitis (n = 22) and were evaluated for epilepsy surgery. Whereas meningitis in this group was commonly associated with mesial temporal sclerosis (MTS), most encephalitis patients had neocortical foci. The age of onset of the encephalitic illness was important in predicting mesial temporal or neocortical foci in that group: encephalitis before, but not after, age 4 years was associated with MTS. Since almost all meningitis occurred before age 4 years, these data support the hypothesis that the medial temporal lobe is particularly susceptible to early insults, establishing the initial pathologic entity of MTS and the subsequent cascade of partial seizures. Later-onset encephalitis produced extrahippocampal neocortical seizure foci, was rarely associated with MRI abnormality, and was difficult to localize precisely. In contrast, meningitis was commonly associated with MTS, aiding seizure localization and successful surgical intervention when seizures were medically uncontrolled.     

Ictal vomiting in a left hemisphere language-dominant patient with left-sided temporal lobe epilepsy

Ictal vomiting in patients with focal epilepsy has mostly been associated with an epileptogenic zone in the non-language-dominant hemisphere. Here we present the case of a left hemisphere language-dominant patient suffering from typical mesial temporal lobe epilepsy with histologically proven hippocampal sclerosis and ictal vomiting during complex partial seizures. He became seizure-free after selective left-sided amygdalohippocampectomy. This case implies that ictal vomiting may not necessitate invasive electrophysiological exploration of left hemisphere language-dominant patients with temporal lobe epilepsy if surface EEG and MRI indicate a left-sided epileptogenic zone. It thus corroborates that with concordant imaging and neurophysiological data, clinical signs become less valuable.     

以癫痫为首发症状的颞叶海绵状血管畸形的手术治疗方式

目的探讨以癫痫为首发症状的颞叶及颞叶内侧海绵状血管畸形的手术治疗方式。方法回顾性分析广东三九脑科医院2009~2013年手术治疗的49例以癫痫为首发症状的颞叶及颞叶内侧海绵状血管畸形患者,其中全面性强直-阵挛性发作26例,复杂部分性发作23例,20例行单纯病灶切除(A组),29例根据术中脑电监测结果,病灶及颞叶及/或内侧结构癫痫灶扩大切除术(B组)。结果采用Engel效果分级,A组中Ⅰ级为70%,Ⅱ级为20%,Ⅲ级10%;病理检查均为海绵状血管畸形。B组中Ⅰ级89.66%,Ⅱ级6.9%,Ⅲ级3.44%;病理检查为海绵状血管畸形,其中25例包括海马硬化,3例皮质发育不良。术中及术后均无明显并发症及死亡患者。结论对以癫痫为首发症状的颞叶海绵状血管畸形患者,通过积极的手术治疗可有效控制癫痫发作。结合术前及术中脑电结果,采用选择性扩大切除癫痫灶,对控制癫痫更为有效。颞叶及颞叶内侧海绵状血管畸形患者可能存在双重病理改变。     

Ictal Contralateral Paresis in Complex Partial Seizures

Summary: Certain behaviors that occur during a complex partial seizure (CPS) are useful in lateralizing the side of seizure onset. In 5 (5.3%) of 94 consecutive patients with partial epilepsy, we observed ictal unilateral arm and hand paresis during 27 of 34 CPS. In all these seizures, this behavior occurred contralateral to an epileptogenic temporal lobe, as determined by video-EEG monitoring and surgical outcome. In 5 of the 27 seizures, an observer demonstrated that the paretic arm and hand were flaccid. None of these patients had postictal (Todd's) paralysis. In most of the seizures, the arm ipsilateral to seizure onset had simultaneous purposeful movements or automatisms, sometimes with awkward posturing. Ictal unilateral paresis is distinctly different from ictal dystonia or postictal paralysis and consistently lateralizes seizure onset to the contralateral temporal lobe. Recognition of this particular ictal behavior and comparison to other simultaneous behaviors can aid in the lateralization and possibly localization of the epileptogenic zone.     

Speech preservation during language-dominant, left temporal lobe seizures: report of a rare, potentially misleading finding

PURPOSE: To evaluate the prevalence and mechanism of ictal speech in patients with language-dominant, left temporal lobe seizures. METHODS: We retrospectively reviewed the video-EEG telemetry records for the presence of ictal speech in 96 patients with surgically proven left temporal lobe epilepsy and studied the seizure-propagation patterns in three patients who required intracranial EEG recordings for seizure localization. RESULTS: Ictal speech preservation was observed in five patients. One patient's seizures demonstrated rapid propagation of the ictal discharges to the contralateral temporal area where the seizure evolved, resembling a nondominant temporal lobe seizure. The other two patients had ictal discharges that remained confined to the inferomesial temporal areas, sparing language cortex. CONCLUSIONS: Preservation of speech in complex partial seizures of language-dominant, left temporal lobe origin is rare. Based on intracranial EEG recordings, the likely mechanism underlying this potentially misleading clinical finding is the preservation of language areas due to limited seizure-propagation patterns.     

Presurgical evaluation in refractory epilepsy secondary to meningitis or encephalitis: bilateral memory deficits often preclude surgery.

We investigated the clinical features and surgical outcome of 17 patients with refractory epilepsy secondary to CNS infection who were referred to a tertiary center for presurgical evaluation. Six patients had a history of meningitis and 11 patients had a history of encephalitis. Median age at infection was three years (40 days-40 years). Time to seizure onset was shorter in the encephalitis group (median of 0.9 years versus 5.9 years in the meningitis group). MRI showed unilateral mesial temporal sclerosis (MTS) in all but one patient with meningitis (5/6). MRI in the encephalitis group showed unilateral MTS (four patients), bilateral MTS (three), porencephalic cysts (one) or no significant findings (three). Seizure semiology, following analysis of 127 seizures, included automotor seizures, complex motor/hypermotor seizures, dialeptic seizures and bilateral asymmetric tonic seizures. Neuropsychological assessment in patients with MTS frequently showed bilateral memory impairment (7 out of 12 MTS-patients), even in 4 patients with unilateral MTS, precluding epilepsy surgery. Six patients (two meningitis and four encephalitis patients) underwent a temporal lobe resection. All patients are either seizure-free (Class 1a) or are having only auras after surgery. One patient from the meningitis group underwent functional hemispherectomy and he is also seizure-free. In our series, MTS was the most common finding in refractory epilepsy after CNS infections. Bilateral memory deficits were often encountered in patients with MTS, even when unilateral, these deficits being a limiting factor for surgery. Good surgical outcome can be expected in selected patients with unilateral MTS and congruent memory deficits.     

Recognition memory of serially or simultaneously presented words or figures, of epilepsy patients with or without mesial temporal sclerosis

Previous studies, examining short-term recognition memory in patients with partial seizures as a consequence of mesial temporal sclerosis (MTS) have reported inconsistent findings. Dependent on the paradigms used for measuring recognition memory, some studies have demonstrated that the mesial temporal structures are not critically involved in short-term recognition memory. In addition, other studies found a lateralization effect that is consistent with the generally accepted association between left temporal lobe lesions and verbal memory deficits, and right temporal lobe lesions and non-verbal memory impairments. In the present study verbal and non-verbal recognition memory was tested in 41 patients with left or right temporal lobe epilepsy with MTS (22 left; 19 right) versus 44 patients with left or right temporal lobe epilepsy but without MTS (28 left; 16 right). Verbal and non-verbal recognition tasks were presented in both a serial and simultaneous condition to test a hypothesized local/global paradigm. Multiple analyses of variance (MANOVA) showed that unilateral MTS has no marked effects on verbal or non-verbal recognition memory of patients with seizures. An interaction effect between MTS and the lateralization of epileptic activity was found on memory performance: MTS only leads to deficits in recognition memory in patients with right-sided epileptiform activity. As hypothesized, patients with left temporal lobe abnormalities, have specific deficits with recognizing serially presented information.     

Intracranial EEG in temporal lobe epilepsy.

Intracranial EEG monitoring before epilepsy surgery, while becoming less commonly performed in patients with unilateral mesial temporal lobe epilepsy, is still widely used when bilateral independent temporal lobe seizures are suspected or when extratemporal foci cannot be ruled out by noninvasive means. Additionally, many epilepsy centers are reporting excellent surgical outcome in patients with neocortical temporal lobe epilepsy, when resections are guided by intracranial EEG studies. This article reviews the indications, technical aspects, risks, and interpretation of intracranial EEG in patients with temporal lobe seizures. It also considers intracranial EEG features predictive of surgical outcome.     

Factors predicting outcome of surgery for intractable epilepsy with pathologically verified mesial temporal sclerosis

PURPOSE: To examine the subgroup of patients with medically intractable epilepsy receiving temporal lobectomies who have pathologically verified mesial temporal sclerosis (MTS) and to determine the relation of demographic and clinical factors, results of diagnostic testing, and details of the surgical procedure with prognosis for achieving control of seizures. METHODS: All patients receiving surgical treatment for intractable epilepsy between 1991 and 1998 at the University of Washington were reviewed. There were 118 patients who met inclusion criteria of adequate pathological analysis showing MTS without a progressive process and a minimum of 1-year follow-up. RESULTS: Only personal history of status epilepticus demonstrated significant (p = 0.0276) prediction of outcome, increasing the risk of surgical failure. No other factors were significant predictors of outcome, including history of febrile seizures, possible etiologic factors, EEG, magnetic resonance imaging (MRI) or neuropsychological testing results, or extent of resection. CONCLUSIONS: Many factors that have been previously described to predict favorable outcome in the overall group of patients receiving temporal lobe resections for intractable epilepsy are, in fact, predictors of MTS and lose their predictive value when the subgroup of patients with confirmed MTS is examined. Neurosurgical treatment of MTS can be very effective even in the presence of significant etiologic factors, or of bilateral or extratemporal abnormalities on EEG or MRI.     

Hypermotor seizures in patients with temporal pole lesions

Hypermotor seizures are considered to be characteristic of frontal lobe epilepsy, with only rare occurrence in temporal lobe epilepsy. After noting hypermotor seizures in several patients with lesions involving the pole of the temporal lobe, we investigated whether temporal pole lesions were associated with hypermotor seizures. We systematically reviewed medical records, MRI images and pathological findings in consecutive patients who underwent epilepsy surgery over the preceding 10 years in our institution and identified eight patients with temporal pole lesions and intractable complex partial seizures. We analyzed all recorded seizures for semiology, classifying seizures as hypermotor or typical "psychomotor." Four patients exhibited hypermotor seizure semiology and four patients manifested typical psychomotor seizure characteristics. In patients with hypermotor seizures, scalp EEG tended to demonstrate lateral anterior temporal ictal onset, with lesser involvement of the sphenoidal electrode, while the patients with psychomotor seizures had initial inferomesial temporal rhythmic theta activity. Two patients with hypermotor seizures had implanted frontal and temporal subdural grids demonstrating orbitofrontal spread before hypermotor behavior. Patients underwent either anterior temporal lobectomy or lesionectomy. All improved considerably, with six patients seizure-free since surgery. We conclude that hypermotor seizures occur frequently in patients with temporal pole lesions. A search for temporal pole pathology is recommended for patients with hypermotor seizures and temporal epileptiform discharges. Modification of the surgical approach to include this region should be considered in patients who exhibit hypermotor seizures.     

Mesial Temporal Lobe Epilepsy in Childhood

Summary: To clarify the clinical picture of mesial temporal lobe epilepsy (MTLE) in childhood, we carried out a clinical, electroencephalographic, and neuroradiologic study of 19 patients. MTLE was noted in 19 (0.82%) of 2,319 epileptic patients with childhood onset. Three types of initial seizure were recognized: febrile convulsion, afebrile generalized convulsion, and complex partial seizure (CPS). As presumed causes, various prolonged convulsions (persisting for >30 min) were found in 12 (63.2%) cases. Regardless of the presence of preceding convulsions (febrile or afebrile), the clinical course was not uniform, with CPS in the early period temporarily controlled in some cases and intractable from the early period in others. Unilateral hippocampal abnormalities were confirmed on magnetic resonance imaging (MRI) before the age of 5 years in two cases, suggesting that mesial temporal sclerosis (MTS) is formed within a relatively short period in some cases. Seizures were controlled for >6 months in only two (10.5%) cases and persisted in 17. In four (21.1%) cases, surgical treatment was considered to be available.     

Ictal patterns in temporal lobe epilepsy recorded by epidural screw electrodes

In a consecutive series of 11 patients with a history of medically refractory temporal lobe epilepsy, we studied the appearance of ictal patterns detected by epidural screw electrodes (ESE) placed in an effort to obviate depth electrode recording. All had prior scalp-sphenoidal monitoring with aignificant obscuration of ictal EEG by movement and muscle artifact. Six to 10 ESE were placed at bilateral temporal locations of the 10% system. Ictal findings in 4–15 partial seizures from 8 patients with mesiobasal (MBTLE) and 3 patients with neocortical (NCTLE) epilepsy were correlated with imaging and histology. Five of 8 patients with MBTLE had discrete high frequency discharges at onset, evolving within 10 s to focal theta at ESE, before appearing at scalp electrodes. All had Class 1A outcome with mesial temporal sclerosis (MTS). Three of 8 patients with MBTLE and MTS had less discrete onsets, with Class 1A, 1B and 3A outcomes. Two patients with NCTLE had lesions; a grade II oligoastrocytoma with rhythmic delta at ESE and Class 4 outcome, and an anterior temporal cavernous angioma with variable onsets, some of which were high frequency, with a Class 1A outcome. The third NCTLE patient demonstrated focal theta as an ictal pattern, had no lesion and a Class 1A outcome. Ictal onsets may be well localized in selected patients by ESE. A majority of patients with MTS display well defined high frequency ictal discharges.     

Long-Term Ambulatory Cassette EEG with Sphenoidal Recording in Complex Partial Seizures

Long-term ambulatory cassette EEG with sphenoidal recording (A/EEG-SP) was performed in 51 patients. Group A comprised 31 patients with a clinical diagnosis of complex partial seizures (CPS), and group B comprised 20 patients suspected of having CPS. In group A, detection of temporal spikes was 27% by routine EEG (R/EEG), 72% by sphenoidal EEG (SP/EEG), 27% by A/EEG with temporal chain montage, and 91% by A/EEG-SP. The highest yield achieved by A/EEG-SP as compared with other EEG recordings was documentation of spontaneous seizures of temporal lobe origin. The detection rate of spontaneous seizures by A/EEG-SP was approximately 30%, and the focal or regional onset of seizures could be determined in 60% of patients. In group B, detection of temporal spikes was 11% by R/EEG, 18% by SP/EEG, and 30% by A/EEG-SP. Spontaneous seizures were recorded by A/EEG-SP in two patients (10%). Thus, A/EEG-SP was more effective than A/EEG in detecting interictal and ictal temporal discharges, and A/EEG-SP was superior to SP/EEG in documenting spontaneous seizures of temporal lobe origin.     

Distinguishing Subtypes of Temporal Lobe Epilepsy with Background Hippocampal Activity

PURPOSE: Two subtypes of temporal lobe epilepsy (TLE) can be defined through clinical observations and analysis of hippocampal tissue resected during surgical procedures for intractable TLE: (a) mesial temporal sclerosis (MTS), which is characterized by extensive changes to the hippocampus and good surgical outcome; and (b) paradoxical temporal lobe epilepsy (PTLE), which is characterized by minimal cell loss and comparatively poorer surgical outcome. Patients in both subtypes have seizures that appear to begin in the medial temporal lobe, but documented differences in substrate and outcome between these subtypes has defined a need to distinguish MTS and PTLE patients before surgery. This report describes a retrospective study to investigate the feasibility of doing so during intracranial monitoring. METHODS: Background EEG epochs, 5 min in duration, were recorded from the anterior hippocampus in 14 (10 MTS and four PTLE) patients with consistent localization of seizure onset to medial temporal structures. The power spectral density (PSD) of the EEG epochs was calculated by a Fourier spectral estimator, and the total signal power and power of the delta, theta, alpha, beta, and gamma frequency bands were submitted to group-to-group comparison. RESULTS: Spectral peaks were observed in the delta band in all PSD estimates and in the theta band in nine of 14 (seven MTS, two PTLE) estimates. The MTS and PTLE subtypes could be distinguished by the total signal power and delta band power. These power measurements were greater in the PTLE subtype. CONCLUSIONS: Both delta and theta spectral components are present in hippocampal background EEGs recorded from patients with TLE. The results indicate that group differences exist in spectral measures of background hippocampal signals recorded from MTS and PTLE subtypes. This suggests both that substrate differences in cellular composition and connectivity are reflected in hippocampal background EEGs and that spectral measurements of these signals may hold promise for tests to identify the group membership of individual patients.     

A Long-Term Follow-Up Study of First Episodes of Idiopathic Status Convulsivus in Childhood: In Relation to Subsequent Epilepsy (Second Report)

Abstract: Fifty-four idiopathic status convulsivus (SC) cases were followed prospectively for a period between 5 :and 21 :years, the average being 13 :years. Three-fourths of the cases had no residuals. There were two patterns of subsequent epilepsy; 1) complex partial seizures (CPS) with or without secondarily generalization (GTS) developed 4.3 ± 3.5 years after febrile SC, 2) unilateral seizures or CPS ± GTS developed 1.2 ± 1.0 years after afebrile SC. The seizure prognosis of these cases was good except for some cases in the former group. There have been two kinds of theories regarding SC and epilepsy until now. One was derived from retrospective studies: SC and/or complex febrile convulsion (FC) were considered the main causes of temporal lobe epilepsy (TLE) producing mesial temporal sclerosis (MTS). Another was derived from prospective studies, in which the relation between FC and TLE was considered weak. Our results revealed that 6 :cases (15%) out of 30 :febrile SC developed epilepsy, and that five of those six cases were diagnosed as CPS. Three of 5 :CPS cases were diagnosed as TLE. Recently the seizure prognosis of operative therapy for TLE—especially the MTS type—has been very favorable. Furthermore, it has become easy to And MTS by Magnetic Resonance Imaging (MRI). So, we emphasize that a precise follow-up study of SC using MRI, EEG, etc., is important in deciding the appropriate therapy for TLE, as well as in the study of the pathogenesis of TLE.     

Results of surgery in patients with bilateral independent temporal lobe spiking (BITLS) with normal MRI or bilateral mesial temporal sclerosis (MTS) investigated with bilateral subdural grids

PURPOSE: The introduction of new technologies in the clinical practice have greatly decreased the number of patients submitted to invasive recordings. On the other hand, some patients with refractory temporal lobe epilepsy have normal MR scans or bilateral potentially epileptogenic lesions. This paper reports the results of invasive neurophysiology and surgical outcome in such patients. METHOD: Sixteen patients were studied. Eleven had normal MRI (Group I) and five had bilateral mesial temporal sclerosis (Group II). All patients had BITLS and non-localizatory seizures on video-EEG monitoring. All patients were implanted bilaterally with 32-contacts subdural grids. They were submitted to a cortico-amygdalo-total hippocampectomy at the side defined by chronic electrocorticography (ECoG). RESULTS: In Group I, seizures came from a single side in nine patients. In nine patients, seizures started at one side, spread to the ipsolateral contacts and contralaterally afterwards. On the other hand, in two Group I patients seizures started in one mesial region and spread to the contralateral parahippocampus and neocortex before spreading to ipsolateral contacts. All patients in Group II had seizures starting unilaterally with focal EcoG onset in the mesial regions. Eight Group I patients are seizure-free and three are in Engel's class II. Eighty percent of Group II patients are seizure-free after surgery and one patient is in Engel's class II. CONCLUSION: Good surgical results can be obtained in patients with BITLS. Patients with normal MRI seem to have a worse prognosis when compared to patients with unilateral or even bilateral MTS. Extensive subdural coverage is essential in patients with normal MRI.