Contralateral temporal hypometabolism on positron emission tomography in temporal lobe epilepsy

Introduction — No detailed case studies report lateralised hypometabolism on positron emission tomography (PET) contralateral to the epileptogenic focus in temporal lobe epilepsy (TLE). Material and methods — We performed ¹⁸F fluorodeoxyglucose (FDG) PET in two intractable TLE patients. Results — One had right temporal interictal spikes on electroencephalography (EEG) and a right medial temporal lobe lesion on magnetic resonance imaging (MRI). FDG-PET showed decreased uptake in the left temporal lobe. Right temporal ictal onset, with bilateral interictal epileptiform activity, occurred on intracranial EEG. He is seizure free after right temporal lobectomy and ganglioglioma resection. The second had right temporal lobe interictal and ictal EEG activity. MRI demonstrated right anteriomedial temporal increased T2 signal. Neuropsychology revealed bilateral cognitive dysfunction. FDG-PET showed left anterior temporal and lateral frontal hypometabolism. He is seizure free after right temporal lobectomy. Conclusion — These findings suggest that regional uptake asymmetry on FDG-PET may be give misleading lateralising information in TLE.     

Changes in Regional Cerebral Blood Flow Beyond the Temporal Lobe in Unilateral Temporal Lobe Epilepsy

Summary: Purpose: Single photon emission computed tomography (SPECT) is widely used to evaluate functional abnormalities during the epileptic event. Changes in regional cerebral blood flow (rCBF) are well defined in patients with temporal lobe epilepsy (TLE) undergoing surgical resection. Nonetheless, the interpretation of ictal abnormalities in CBF beyond the temporal lobes has not been carefully addressed.
Methods : We assessed 4 patients with pathologically proven unilateral TLE who had significant ipsilateral frontal hypoperfusion in ictal studies with no other abnormalities but chronic epilepsy accounting for such findings. Patients were assessed as candidates for surgery by interictal EEG, neuropsychological studies, brain magnetic resonance imaging, scalp electrode video-EEG monitoring, and ictal SPECT.
Results : Characteristic hyperperfusion was evident over the temporal lobe ipsilateral to the EEG focus, with significant hypoperfusion over the frontal region in 3 patients. In patient 4, frontal hypoperfusion was not statistically significant.
Conclusions : SPECT demonstrated relative rCBF changes beyond the epileptogenic zone in unilateral TLE. Our findings provide further insight into the pathophysiological changes underlying this condition.     

Small temporal pole encephaloceles: A treatable cause of “lesion negative” temporal lobe epilepsy

Epilepsy due to encephaloceles of the temporal pole may be an under recognized, treatable cause of refractory temporal lobe epilepsy (TLE). We describe three adult patients initially labeled “lesion negative” TLE. In all, video–electroencephalography (EEG) revealed ictal theta in the left temporal region and positron emission tomography (PET) showed temporal lobe hypometabolism, but neuropsychology revealed preserved verbal memory. Close inspection of structural magnetic resonance imaging (MRI) suggested subtle abnormalities at the tip of the left temporal lobe. High resolution computed tomography (CT) confirmed bony defects in the inner table of the skull. 3T MRI with fine coronal and sagittal slices indicated cerebrospinal fluid (CSF) and brain tissue protruding into the defects. All proceeded to resection of the temporal tip and became seizure free. Patients with “lesion negative” TLE should have careful review of images covering the temporal pole. If encephalocele is suspected, further imaging with high‐resolution CT and MRI can be helpful. Temporal polar resection, sparing mesial structures, appears to be curative.     

Temporal lobe epilepsy presenting as panic attacks: detection of interictal hypometabolism with positron emission tomography.

Cerebral glucose metabolism was studied using positron emission tomography (PET) in a 13-year-old girl with a history of panic attacks that were thought to be of psychiatric origin. Positron emission tomography imaging revealed marked right temporal lobe hypometabolism and magnetic resonance imaging (MRI) detected T2 changes consistent with right mesial temporal sclerosis. Electroencephalogram (EEG) studies 3 years later confirmed a primary diagnosis of right temporal lobe epilepsy. As shown by this case and one other, PET and MRI imaging of patients with panic disorder who are thought to have epilepsy may be helpful in leading to definitive electrographic studies that confirm temporal lobe epilepsy as the primary diagnosis.     

发作间期PET对难治性颞叶癫痫的诊断价值

目的分析18例颞叶癫痫患者的正电子发射断层扫描(PET)结果.方法 18例难治性癫痫患者,根据临床症状、脑电图/录像脑电监测(EEG/VEEG)、MRI海马相和单光子发射计算机体层摄影(SPECT)检查诊断为颞叶癫痫.均进行PET检查,结果有16例显示不同程度的颞叶前中部和(或)内侧部的低代谢区域.所有患者均在手术显微镜下采用显微外科技术进行手术,其中右侧颞叶癫痫16例行标准前颞叶及海马杏仁核切除术,左侧颞叶癫痫2例行选择性海马杏仁核切除术.结果随诊观察6～26个月,按照Engel的疗效判断标准,结果I级(癫痫发作消失)11例,II级(极少发作)4例,III级(发作减少75%以上)2例,IV(无改变)1例.结论对于临床上怀疑为颞叶癫痫而上述常规检查方法不能明确癫痫灶者,PET能更好地帮助诊断.     

Surgical outcome and prognostic factors of cryptogenic neocortical epilepsy

Surgical treatment of cryptogenic neocortical epilepsy is challenging. The aim of this study was to evaluate surgical outcomes and to identify possible prognostic factors including the results of various diagnostic tools. Eighty-nine patients with neocortical epilepsy with normal magnetic resonance imaging (35 patients with frontal lobe epilepsy, 31 with neocortical temporal lobe epilepsy, 11 with occipital lobe epilepsy, 11 with parietal lobe epilepsy, and 1 with multifocal epilepsy) underwent invasive study and focal surgical resection. Patients were observed for at least 2 years after surgery. The localizing values of interictal electroencephalogram (EEG), ictal scalp EEG, interictal 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), and subtraction ictal single-photon emission computed tomography were evaluated. Seventy-one patients (80.0%) had a good surgical outcome (Engel class 1-3); 42 patients were seizure free. Diagnostic sensitivities of interictal EEG, ictal scalp EEG, FDG-PET, and subtraction ictal single-photon emission computed tomography were 37.1%, 70.8%, 44.3%, and 41.1%, respectively. Localization by FDG-PET and interictal EEG was correlated with a seizure-free outcome. The localizing value of FDG-PET was greatest in neocortical temporal lobe epilepsy. The focalization of ictal onset and also ictal onset frequency in invasive studies were not related to surgical outcome. Concordance with two or more presurgical evaluations was significantly related to a seizure-free outcome.     

Unitemporal vs bitemporal hypometabolism in mesial temporal lobe epilepsy

BACKGROUND: Patients with mesial temporal lobe epilepsy (TLE) often show bilateral temporal hypometabolism (BTH), but the nature of this finding has not been well established. OBJECTIVE: To compare the clinical characteristics between unitemporal hypometabolism (UTH) and BTH patients in mesial TLE. DESIGN: Cross-sectional study. SETTING: Epilepsy center at university hospital in Seoul, Korea. PATIENTS: We enrolled 95 patients with mesial TLE, 87 of whom had subsequently undergone surgery. Seizures, interictal and ictal electroencephalography (EEG), brain magnetic resonance imaging, Wada test, and neuropsychological test results were reviewed. (18)F-fluorodeoxyglucose positron emission tomography scans were interpreted visually. Patients were divided into 2 groups: UTH and BTH. RESULTS: There were 59 UTH patients and 36 BTH patients. Semiologic analysis showed that UTH patients had higher frequencies of aura and unilateral dystonic posturing, whereas BTH patients had higher frequencies of a nonlateralized bilateral ictal EEG pattern and bilateral interictal spikes. Moreover, BTH patients had more frequent symmetric Wada memory scores and white matter changes in the bilateral temporal lobes on brain magnetic resonance imaging than UTH patients. All UTH patients with bilateral TLE on scalp EEG showed unilateral seizure onset on intracranial EEG. CONCLUSIONS: The characteristic clinical findings of mesial TLE with BTH were a more frequent nonlateralized ictal EEG pattern, bitemporal interictal spikes, symmetric Wada memory score, and the anterior temporal white matter changes, and less frequent aura and unilateral dystonic posturing. Surgical outcomes were similar and good in both groups, although surgery could not be performed in 8 BTH patients (22%).     

Lack of aura experience correlates with bitemporal dysfunction in mesial temporal lobe epilepsy

The diagnostic value of lack of aura experience in patients with temporal lobe epilepsy (TLE) is unclear. PURPOSE: To evaluate possible factors of bitemporal dysfunction in patients with mesial TLE who did not experience an aura in electroencephalography EEG/video monitoring for epilepsy surgery. METHODS: Ictal scalp EEG propagation patterns of 347 seizures of 58 patients with mesial temporal lobe sclerosis or non-lesional mesial TLE, interictal epileptiform discharges (IED), presence of unilateral mesial temporal lobe sclerosis in visual magnetic resonance imaging (MRI) analysis, prose memory performance, history or not of an aura, and postictal memory or absence of an aura were analyzed. The ictal EEG was categorized as follows. EEG seizure: (a) remaining regionalized, (b) non-lateralized, (c) showing later switch of lateralization or bitemporal asynchronous ictal patterns. RESULTS: Absent aura in monitoring was significantly correlated with absence of unitemporal MRI sclerosis (P=0.004), bitemporal IED (P=0.008), and propagation of the ictal EEG to the contralateral temporal lobe (P=0.001). Other historical data and interictal prose memory performance were not significantly correlated with absent aura. Ten of 11 patients without aura in monitoring also had absent or rare auras in their history. CONCLUSIONS: Lack of aura experience strongly correlates with indicators of bitemporal dysfunction such as bitemporal interictal sharp waves and bitemporal ictal propagation in scalp EEG, and absence of lateralized MRI sclerosis in patients with mesial TLE. The fact that absent auras are not correlated with episodic memory suggests a transient memory deficit, probably because of rapid propagation to the contralateral mesial temporal lobe.     

Nontumoral occipitotemporal epilepsy: localizing findings and surgical outcome

We describe a syndrome of medically intractable occipitotemporal epilepsy of nontumoral developmental origin and its treatment by surgery. From our epilepsy surgery database of 1988 to 1996, we selected all patients without neoplasm who had at least two characteristics localizing to the occipital lobe (clinical symptoms, interictal focus, ictal onset, or a lesion on magnetic resonance imaging scanning) and one to the temporal lobe (interictal spikes or seizure onset). We discuss seizure characteristics, electroencephalographic (EEG), magnetic resonance imaging, positron emission tomographic, and single-photon emission computed tomographic findings, pathological findings, surgical approach, outcome from resective surgery, and implications for pathophysiology. Sixty-nine percent of our 16 patients with occipitotemporal syndrome had neuronal migration disorder, suggesting a developmental etiology of this entity. Initial signs or symptoms suggested occipital lobe seizure onset in 13 of 16 patients. On scalp EEG, interictal spikes were localized to the temporal lobe in 9 and to the occipital lobe in 1; seizure onset was poorly localized. Intracranial EEG localized seizure onset to the area of temporo-occipital junction in 77% of patients. Positron emission tomography and single-photon emission computed tomography showed occipital and temporal or widespread deficits, and neuropsychological performance was diffusely abnormal. Surgical results were best with occipital and temporal resections, but sometimes satisfactory after occipital resection even with temporal (ipsilateral) EEG findings. Temporal resection with hippocampectomy uniformly failed to control seizures. An often refractory, probably developmental epileptic syndrome with regional occipitotemporal distribution can be diagnosed by a specific constellation of findings, which has implications for treatment and pathophysiology.     

The contribution of 18F-FDG PET in preoperative epilepsy surgery evaluation for patients with temporal lobe epilepsy A meta-analysis.

OBJECTIVE: To assess the predictive diagnostic added value of positron emission tomography (PET) in preoperative epilepsy surgery evaluation for patients with temporal lobe epilepsy (TLE). METHODS: A meta-analysis of publications from 1992 to 2006 was performed. Forty-six studies were identified that met inclusion criteria presenting detailed diagnostic test results and a classified postoperative outcome. Studies exclusively reporting on patients with brain tumors or on children were excluded. RESULTS: The analyses were complicated by significant differences in study design and often by lack of precise patient data. Ipsilateral PET hypometabolism showed a predictive value of 86% for good outcome. The predictive value was 80% in patients with normal MRI and 72% in patients with non-localized ictal scalp EEG. In a selected population of 153 TLE patients with a follow-up of >12 months PET correlated well with other non-invasive diagnostic tests, but none of the odds ratios of any test combination was significant. CONCLUSION: Our data confirm that ipsilateral PET hypometabolism may be an indicator for good postoperative outcome in presurgical evaluation of drug-resistant TLE, although the actual diagnostic added value remained questionable and unclear. PET does not appear to add value in patients localized by ictal scalp EEG and MRI. Prospective studies limited to non-localized ictal scalp EEG or MRI-negative patients are required for validation.     

Localization of epileptogenic zone in temporal lobe epilepsy by ictal scalp EEG.

Our aim was to evaluate the ability to localize the epileptogenic zone in temporal lobe epilepsy (TLE) by ictal scalp electroencephalogram (EEG). Using simultaneous video recording, we analysed scalp EEG activity during ictal periods in 38 patients (30 patients with medial TLE (MTLE) and eight with lateral TLE (LTLE)). In 14 patients, intracranial ictal EEGs were recorded with depth electrodes, and simultaneous recordings of scalp and intracranial EEG were performed in 11 patients. Scalp EEG showed that, in all 30 patients with MTLE (71 of 72 seizures), an attenuation of background activity was observed before the appearance of ictal activity. Ictal discharges first appeared in the scalp EEG when the ictal discharges reached the lateral part of the temporal lobe on the intracranial EEG. While, in all eight patients with LTLE (25 of 25 seizures), the attenuation of background activity did not occur before the appearance of ictal activity. When the ictal discharges started in the lateral temporal lobe on intracranial EEG, ictal discharges appeared on the scalp. MTLE and LTLE could be diagnosed by the presence or absence of attenuation of background activity with clinical ictal signs before the appearance of ictal discharges.     

Clinical Usefulness of the Dipole Tracing Method for Localizing Interictal Spikes in Partial Epilepsy

Summary: Purpose: To clarify the clinical usefulness of the dipole tracing method in evaluation of interictal EEG spikes in patients with partial epilepsy.
Methods : Eight patients with partial epilepsy were studied. We compared the generator source of interictal spikes detected by the dipole tracing method with the results of magnetic resonance imaging (MRI), interictayictal measurement of cerebral blood flow (CBF) by single photon emission computed tomography (SPECT), interictal measurement of glucose metabolism by positron emission tomography (PET) and invasive electrocorticogram (ECoG).
Results : In 5 patients with mesial temporal lobe epilepsy (TLE), including 3 patients who underwent standard temporal lobectomy, the dipole tracing method showed results consistent with those of other examinations and better correlation with ECoG than with other noninvasive examinations. In a patient with mesial TLE who had defects in the skull due to previous surgery, the dipoles were located more laterally than expected. In a patient with frontal lobe epilepsy (FLE) who was finally proved to have an epileptogenic area in the lateral frontal area, the spike dipoles were identified in the medial side of the frontal lobe.
Conclusions : The dipole tracing method used in the present study is useful for localizing epileptogenic areas in patients with mesial TLE. However, in patients with partial skull defects and in those with FLE, the reliability of this method is still in accuracy of the lobe level.     

Seizure outcome after anterior temporal lobectomy and its predictors in patients with apparent temporal lobe epilepsy and normal MRI

PURPOSE: Very little reliable information is available regarding the role of anterior temporal lobectomy (ATL), optimal presurgical evaluation strategy, post-ATL seizure outcome, and the factors that predict the outcome in patients with medically refractory temporal lobe epilepsy (TLE) and normal high-resolution magnetic resonance imaging (MRI). To be cost-effective, epilepsy surgery centers in developing countries will have to select candidates for epilepsy surgery by using the locally available technology and expertise. METHODS: We reviewed the electroclinical and pathological characteristics and seizure outcome of 17 patients who underwent ATL for medically refractory TLE after being selected for ATL based on a noninvasive selection protocol without the aid of positron emission tomography (PET) or single-photon emission computed tomography (SPECT), despite a normal preoperative high-resolution MRI. RESULTS: Seven (41%) patients achieved an excellent seizure outcome; five of them were totally seizure free. An additional five (29%) patients had >75% reduction in seizure frequency. The following pre-ATL factors predicted an excellent outcome: antecedent history of febrile seizures, strictly unilateral anterior temporal interictal epileptiform discharges (IEDs), and concordant type 1 ictal EEG pattern. All the five patients with pathologically verified hippocampal formation neuronal loss were seizure free. The presence of posterior temporal, bilateral temporal, and generalized IEDs portended unfavorable post-ATL seizure outcome. CONCLUSIONS: A subgroup of patients destined to have an excellent post-ATL outcome can be selected from MRI-negative TLE patients by using history and scalp-recorded interictal and ictal EEG data. The attributes of these patients are antecedent history of febrile seizures, strictly unilateral anterior IEDs, and concordant type 1 ictal EEG pattern.     

EEG source imaging in pediatric epilepsy surgery: a new perspective in presurgical workup

PURPOSE: Epilepsy is a relatively frequent disease in children, with considerable impact on cognitive and social life. Successful epilepsy surgery depends on unambiguous focus identification and requires a comprehensive presurgical workup, including several neuroimaging techniques [magnetic resonance imaging, positron emission tomography (PET), and single-photon emission computed tomography (SPECT)]. These may be difficult to apply in younger or developmentally delayed children or both, requiring sedation, and hence, a significant workforce. Modern electric source imaging (ESI) provides accurate epileptic source-localization information in most patients, with minimal patient discomfort or need for cooperation. The purpose of the present study was to determine the usefulness of ESI in pediatric EEG recordings performed with routine electrode arrays. METHODS: Preoperative EEGs recorded from 19 to 29 scalp electrodes were reviewed, and interictal epileptiform activity was analyzed by using a linear source-imaging procedure (depth-weighted minimum norm) in combination with statistical parametric mapping. RESULTS: In 27 (90%) of 30 patients, the ESI correctly localized the epileptogenic region. These numbers compare favorably with the results from other imaging techniques in the same patients (PET, 82%; ictal SPECT, 70%). In extratemporal epilepsy, ESI was correct in all cases, and in temporal lobe epilepsy, in 10 of 13 cases. In two temporal lobe patients showing less-accurate ESI results, 128-electrode data could be analyzed, and in both cases, the 128-electrode ESI was correct. CONCLUSIONS: ESI with standard clinical EEG recordings provides excellent localizing information in pediatric patients, in particular in extratemporal lobe epilepsy. The lower yield in temporal lobe epilepsy seems to be due to undersampling of basal temporal areas with routine scalp recordings.     

Combined imaging of epileptic foci and brain metabolism using MEG and FDG-PET]

A 17-year-old woman developed left hemiparesis at the age 6 months. She had suffered from focal motor seizures associated with tonic extension of her left extremities since the age of 10 years. The interictal scalp EEG demonstrated frequent spike-and-slow-wave complexes dominantly in the right frontal area. MRI showed an old cerebral infarction in the right frontal lobe. Simultaneous recordings of magnetoencephalography (MEG) and EEG were obtained by using a 204-channel whole-head MEG system. Equivalent current dipoles (ECDs) calculated from epileptic spikes on MEG were scattered in the cortex adjacent to the lesion in the right frontal lobe. Positron emission tomography with 18-fluoro-2-deoxyglucose (FDG-PET) in the interictal state showed hypometabolism in the lesion and its adjacent area. The super-imposed images of the dipole and PET showed that epileptic foci surrounded the lesion. The multimodality imaging is useful for evaluation of patients with epilepsy for possible indication of surgery.     

Epilepsy surgery in patients with bilateral temporal lobe seizures: A systematic review

We explored the association between magnetic resonance imaging (MRI) lesion, degree of seizure laterality on intracranial electroencephalography (iEEG), and seizure outcome in patients with ambiguous or presumed bilateral temporal lobe epilepsy (BiTLE) on scalp EEG. We systematically reviewed the literature using Embase and MEDLINE up to May 31, 2012. Patients with bilateral iEEG, temporal lobe surgery, and follow‐up ≥1 year were included. We undertook three separate analyses on patients whose scalp EEG showed ambiguous onset or BiTLE (1) group data of those whose iEEG demonstrated unilateral TLE, (2) group data of those whose iEEG demonstrated BiTLE, (3) individual patient analysis in those with BiTLE for whom iEEG seizure laterality data were provided. Of 1,403 patients with ambiguous or presumed BiTLE on scalp EEG, 1,027 (73%) proved to have unilateral TLE on iEEG and contributed to the first analysis. Of these, 58% had Engel class I and 9% Engel class II outcomes. Of 132 patients in the second analysis (true BiTLE), Engel class I and II outcomes were achieved in 23% and 14%, respectively. Of 41 patients in the third analysis, 66% and 2% had Engel class I and II outcomes, respectively. The median proportion of seizures ipsilateral to the resection on iEEG did not differ between BiTLE patients with Engel class I–II (76%) and Engel III–IV (78%) outcomes (p = 0.87). Patients with ambiguous or independent bitemporal seizure onset on scalp EEG achieved good surgical outcomes. Overall, a significantly higher proportion of patients achieved good outcomes when iEEG showed unilateral TLE (67%) than when it showed true BiTLE (45%). However, the degree of seizure lateralization in those with BiTLE was not associated with seizure outcome, and it has a limited role in selecting the side of surgery.     

Continuous Source Imaging of Scalp Ictal Rhythms in Temporal Lobe Epilepsy

Summary: Purpose: We wished to determine whether continuous EEG source imaging can predict the location of seizure onset with sublobar accuracy in temporal lobe epilepsy (TLE).
Methods : We retrospectively analyzed the earliest scalp ictal rhythms, recorded with 23- to 27-channel EEG, in 40 patients with intractable TLE. A continuous source analysis technique with multiple fixed dipoles (Focus 1.1) decomposed the EEG into source components representing the activity of major cortical sublobar surfaces. For the temporal lobe, these were basal, anterior tip, anterolateral, and posterolateral cortex. Ictal EEG onset was categorized according to its most prominent and leading source component. All patients underwent intracranial EEG studies before epilepsy surgery, and all had a successful surgical outcome (follow-up >1 year).
Results : Most patients with ictal rhythms having a predominant basal source component had hippocampal-onset seizures, whereas those with seizures with prominent lateral source activity had predominantly temporal neocortical seizure origins. Seizures with a prominent anterior temporal tip source component mostly had onset in entorhinal cortex. Seizures in some patients had several equally large and nearly synchronous source components. These seizures, which could be modeled equally well by a single oblique dipole, had onset predominantly in either entorhinal or lateral temporal cortex.
Conclusions : Multiple fixed dipole analysis of scalp EEG can provide information about the origin of temporal lobe seizures that is useful in presurgical planning. In particular, it can reliably distinguish seizures of mesial temporal origin from those of lateral temporal origin.     

Interictal 99mTc-HMPAO SPECT in temporal lobe epilepsy: relation to clinical variables

PURPOSE: Factors affecting blood flow observed by interictal single-photon emission computed tomography (SPECT) images in temporal lobe epilepsy (TLE) have not been systematically studied or consistently demonstrated. We evaluated interictal SPECT results with respect to many clinical variables in a large population of TLE patients, all of whom underwent temporal lobectomy. METHODS: Interictal 99mTc-HMPAO SPECT scans from 61 TLE patients were obtained before an anterior temporal lobectomy. SPECT was analyzed using a region of interest analysis (ROI) in the cerebellum, anterior temporal lobe, lateral temporal lobe, mesial temporal lobe, whole temporal lobe, and inferior frontal lobe. Asymmetry indices (AIs) were calculated. Correlative analysis of AIs and clinical variables was performed. RESULTS: The AIs from TLE patients differed significantly from those of controls in the anterior temporal (p < 0.01), lateral temporal (p < 0.001), and whole temporal (p < 0.01) regions. No consistent overall correlation between the AIs and clinical variables existed. In right TLE (RTLE) only, AIs in the lateral and whole temporal lobe were positively correlated with age of onset (r = 0.470, p < 0.05; r = 0.548, p < 0.01, respectively). Similarly, in RTLE only, duration of epilepsy was negatively correlated with the anterior (r = -0.395, p < 0.05) and mesial (r = -0.45, p < 0.05) temporal lobe AI. No correlations were found between clinical variables and AIs in left TLE (LTLE) patients. CONCLUSIONS: Significant correlation of age at onset and duration of epilepsy with AIs in RTLE but not LTLE suggests physiologic processes may be determined in part by laterality of TLE. Clinical applications are problematic.     

Frequency of bitemporal independent interictal epileptiform discharges in temporal lobe epilepsy

PURPOSE: Bitemporal interictal epileptiform discharges (IEDs) occur in < or =42% of scalp EEGs in patients with temporal lobe epilepsy (TLE) studied with routine EEGs or partial analysis of long-term recordings. METHODS: Twenty-eight patients with TLE demonstrating exclusively unilateral temporal IEDs on routine EEGs underwent 24-h continuous recording. The entire record was visually inspected for epileptiform discharges. We used continuous EEG to assess the significance of long-term recording in detecting bilateral IEDs. RESULTS: Twenty-two patients had left temporal IEDs; 21 had right temporal IEDs. Seventeen (61%) patients had IEDs originating from both the right and left temporal lobes. The probability of detecting bilateral independent IEDs was correlated with the duration of continuous EEG recording. There was no correlation between the number of IEDs originating from one side and the probability of detecting independent IEDs on the other side. The frequencies of IEDs were not correlated with the length of time since onset of epilepsy. CONCLUSIONS: The findings suggest that when long-term recordings are performed, the incidence of bilateral discharges in TLE is higher than previously reported in the literature and supports the view that TLE is commonly a bilateral disease.     

Ictal spitting in left temporal lobe epilepsy: report of three cases.

PURPOSE: Ictal spitting is rarely reported in patients with epilepsy. More often it is observed in patients with temporal lobe epilepsy (TLE) and is presumed to be a lateralizing sign to language nondominant hemisphere. We report three patients with left TLE who had ictal spitting registered during prolonged video-EEG monitoring. METHODS: Medical charts of all patients with medically refractory partial epilepsy submitted to prolonged video-EEG monitoring in the Epilepsy Unit at UNIFESP during a 3-year period were reviewed, in search of reports of ictal spitting. The clinical, neurophysiological and neuroimaging data of the identified patients were reviewed. RESULTS: Among 136 patients evaluated with prolonged video-EEG monitoring, three (2.2%) presented spitting automatisms during complex partial seizures. All of them were right-handed, and had clear signs of left hippocampal sclerosis on MRI. In two patients, in all seizures in which ictal spitting was observed, EEG seizure onset was seen in the left temporal lobe. In the third patient, ictal onset with scalp electrodes was observed in the right temporal lobe, but semi-invasive monitoring with foramen ovale electrodes revealed ictal onset in the left temporal lobe, confirming false lateralization in surface records. The three patients became seizure-free following left anterior temporal lobectomy. CONCLUSIONS: Ictal spitting is a rare finding in patients with epilepsy, and may be considered a localizing sign of seizure onset in the temporal lobe. It may be observed in seizures originating from the left temporal lobe, and thus should not be considered a lateralizing sign of nondominant TLE.