Focal CT abnormality and epileptogenic focus

In 31 patients with temporal lobe epilepsy, the precise site of epileptogenic focus was determined by means of a depth EEG recording as one of the presurgical evaluations. In 13 patients, a CT scan revealed focal lesions; 7 in the left temporal lobe and 6 in the right temporal lobe. In 5 of the 7 patients and in 5 of the 6 patients the epileptogenic foci were determined in the temporal lobe on the side of a CT lesion. However, in 2 of the patients with a CT lesion in the left temporal lobe, independent epileptogenic foci were found in both the temporal lobes, and in the other patient with a CT lesion in the right temporal lobe, they were found in the right frontal and left temporal lobes. Thus, the CT lesions agreed in lateralization and focality with the epileptogenic foci in 10 of the 13 patients (77%), but they disagreed in 3 (23%). A CT lesion disclosed in the temporal lobe does not necessarily indicate the side and/or site where the epileptogenic focus may be localized. Although exceptions may be made, spatial disagreement was exemplified between the CT lesion and epileptogenic focus. Therefore, extreme caution has to be taken on the side and/or site of the epileptogenic focus when functional surgical indication is to be made.     

Calcification of the pineal gland: relationship to laterality of the epileptic foci in patients with complex partial seizures.

The right and left temporal lobes differ from each other with respect to the rate of intrauterine growth, the timing of maturation, rate of aging, anatomical organization, neurochemistry, metabolic rate, electroencephalographic measures, and function. These functional differences between the temporal lobes underlies the different patterns of psychopathology and endocrine reproductive disturbances noted in patients with temporolimbic epilepsy. The right hemisphere has greater limbic and reticular connections than the left. Since the pineal gland receives direct innervation from the limbic system and the secretion of melatonin is influenced by an input from the reticular system, I propose that lesions in the right temporal lobe have a greater impact on pineal melatonin functions as opposed to those in the left dominant temporal lobe. Consequently, since calcification of the pineal gland is thought to reflect past secretory activity of the gland, I predicted a higher prevalence of pineal calcification (PC) in epileptic patients with right temporal lobe as opposed to those with left temporal lobe foci. To investigate this hypothesis, the prevalence of PC on CT scan was studied in a sample of 70 patients (43 men, 27 women, mean age: 29.2 years, range 9-58; SD = 10.1) with complex partial seizures, of whom 49 (70.0%) had a right temporal lobe focus. PC was present in 51 patients (72.8%) and was unrelated to any of the historical and demographic data surveyed. In the patients with a focus in the right temporal lobe, PC was present in 46 cases (93.8%) as compared to 5 of 21 patients (23.8%) with left temporal lobe foci.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative magnetic resonance imaging in temporal lobe epilepsy: relationship to neuropathology and neuropsychological function.

Magnetic resonance images (MRIs) were obtained from 25 patients with medically refractory epilepsy of temporal lobe origin (12 on the left, 13 on the right) and 14 right-handed control subjects. The hippocampi and temporal lobes were traced by computer on successive coronal images and the resulting measurements of area were summed for each region. The left and right hippocampi were symmetrical in the control subjects; however, for patients the hippocampus was smaller on the side of the seizure focus. Moreover, the left-right hippocampal ratio significantly differentiated the control subjects from each patient group. The left temporal lobe was significantly smaller than the right in control subjects. The epileptics' temporal lobes were smaller on the side of the seizure focus, compared to the temporal lobes in the control subjects. MRI hippocampal measurements were compared to hippocampal neuronal densities obtained postoperatively. Significant correlations were obtained between the ratio (side ipsilateral to focus/side contralateral to focus) of MRI hippocampal measurements and neuronal densities in all hippocampal subfields except CA2. Prior to surgery, patients were administered the Wechsler Memory Scale and the verbal Selective Reminding Test. Significant correlations existed between MRI measurements of the left hippocampus and the Wechsler logical memory percent retention scores and between the left temporal lobe measurements and the verbal Selective Reminding Test scores for patients with seizure foci in the left temporal lobe.     

MRI lesion and epileptogenic focus in temporal lobe epilepsy

The spatial relationship between a circumscribed lesion in the temporal lobe detected by MRI and an epileptogenic focus identified by ictal depth EEG along with a correlation of the MRI lesion with neuropathological findings were investigated in patients with medically intractable temporal lobe epilepsy but without any focal lesion on CT. Four parameters (an areal ratio of the temporal lobe against the hemisphere, area and calculated T1, T2 values of the hippocampus) were used to determine the abnormal MRI side. An agreement was reached in 67-72% of 18 patients between the abnormal values of the hippocampal area and of calculated T1, T2 and the side of the epileptogenic focus. In 14 of 17 patients, typical hippocampal sclerosis was demonstrated in resected tissue in accordance with the MRI lesions (atrophy and/or prolonged T2 of hippocampus). These results imply: 1) MRI abnormality thus defined may, if not all, indicate the side of the epileptogenic focus, and 2) also the presence of hippocampal sclerosis. It was emphasized that the MRI lesion would be a usable instrument to explore the causal relationship of hippocampal sclerosis to a generation of epileptogenic lesions as well as for presurgical evaluation.     

MRI Lesion and Epileptogenic Focus in Temporal Lobe Epilepsy

Abstract: The spatial relationship between a circumscribed lesion in the temporal lobe detected by MRI and an epibptogenic focus identified by ictal depth EEG along with a correlation, of the MRI lesion with neuropath logical findings were investigated in patients with medically intractable temporal lobe epilepsy but without any focal lesion on CT. Four parameters (an areal ratio of the temporal lobe against the hemisphere, area and calculated T1, T2 values of the hippocampus) were used to determine the abnormal MRI side. An agreement was reached in 67–72%, of 18 patients between the abnormal values of the hippocampus area and of calculated T1, T2 and the side of the epileptogenic focus. In 14 of 17 patients, typical hippocampus sclerosis was demonstrated in respected tissue in accordance with the MRI lesions (atrophy and/or prolonged T2 of hippocampus). These results imply: 1) MRI abnormality thus defined may, if not all, indicate the side of the epileptogenic focus, and 2) also the presence of hippocampal sclerosis. It was emphasized that the MRI lesion would be a usable instrument to explore the causal relationship of hippocampus sclerosis to a generation of epileptogenic lesions as well as for presurgical evaluation.     

Electrophysiologic pathologic correlations in patients with complex partial seizures

We studied interictal activity and site of ictal onset in 26 patients with complex partial seizures of temporal lobe origin. All patients had prolonged electrocorticographic recordings from subdural electrode arrays placed both over the convexity and beneath the temporal lobe. We found a significant correlation between the epileptogenic focus and the type of pathologic lesion found at time of surgery. Macroscopic lesions strongly tended to have an epileptogenic focus on the lateral surface of the temporal lobe; patients with only microscopic abnormalities tended to have an epileptogenic focus in the mesial/basal region of the temporal lobe.     

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Different localizations underlying cortical gelastic epilepsy: Case series and review of literature

BackgroundGelastic seizures (GS) are classically observed with hypothalamic hamartomas but they can also be associated with cortical epileptogenic foci.ObjectiveTo study the different cortical localizations associated with GS.MethodsWe reviewed the data from all patients with cortical GS investigated in our epilepsy unit from 1974 to 2012 and in the literature from 1956 to 2013.ResultsSixteen cases were identified in our database and 77 in the literature. Investigations provided confident focus localization in 9 and 18, respectively. In our series, the identified foci were located in the mesial temporal structures (2 left, 1 right), lateral temporal cortex (1 right), superior frontal gyrus (1 left), and operculoinsular region [3 right (orbitofrontal or frontal operculum extending into the anterior insula) and 1 left (frontal operculum extending into the anterior insula)]. In the literature, the identified foci (13 right/5 left) were located in the temporal lobe of 4 (1 right inferior, 1 right medial and inferior, 1 right posterior middle, inferior extending posteriorly to the lingual gyrus, and 1 left middle, inferior, and medial), in the frontal lobe of 12 [10 (6 right/4 left) medial (i.e., superior, medial frontal, and/or anterior cingulate gyri), 1 lateral (right anterior inferior frontal gyrus), and 1 right medioposterior orbitofrontal cortex] and in the parietal lobe of 2 (1 left superior parietal lobule and 1 right parietal operculum) patients.ConclusionIctal laughter is a poorly lateralizing and localizing feature as it may be encountered in patients with a focus in the left or right frontal, temporal, parietal, or insular lobe.     

Hippocampal volume and glucose metabolism in temporal lobe epileptic foci

PURPOSE: Reports conflict on the relation of glucose metabolism to hippocampal volume in temporal lobe foci. Previous studies usually have used side-side ratios rather than regional metabolic rates. METHODS: We measured hippocampal volume and glucose metabolism in 37 patients with temporal epileptogenic zones identified by ictal video-EEG telemetry. Metabolic rates were normalized to global brain mean. RESULTS: Both 18-fluoro-2-deoxyglucose-PET and volumetric MRI lateralized the epileptic focus determined by ictal video-EEG. There were significant correlations between left-right metabolic asymmetry and hippocampal formation volume left-right ratios. Comparisons between normalized metabolism and hippocampal formation volume, ignoring the side of the epileptic focus, showed significant relations between left hippocampal volume and left inferior lateral temporal metabolism, right hippocampus and right inferior mesial temporal, and left hippocampus and left inferior mesial temporal metabolism. In contrast, when normalized metabolism was compared with hippocampal volume in the epileptic focus, no relation was found. CONCLUSIONS: Our study suggests that the relation between hippocampal volume and glucose metabolism breaks down in epileptic foci and that hypometabolism is not dependent on neuronal loss. It is consistent with data suggesting that hypometabolism is an independent predictor of surgical outcome.     

A case of coexistence with cavernous angioma and focal cortical dysplasia]

There have recently been a number of new pathological findings of specimens from epileptic foci that have become widespread of surgical treatment. We reported a case with seizures resulting from brain lesions which pathologically demonstrated a coexistence with a cavernous angioma and a focal cortical dysplasia. A 24-year-old man was admitted to our hospital because of generalized convulsion from 1 year ago. Brain MRI revealed an enhanced mass lesion, in diameter 1.5 cm, with hemosiderin rim in the left temporal tip. Ictal EEG showed the initiation of the spike from the lateral side of the left temporal lobe. Because the epileptogenic focus was thought to be the lateral side in the left temporal lobe, anterolateral temporal resection was performed and subsequently total removal of the tumor was performed. He had no seizure after surgery. A light microscopic examination was performed on specimens stained with hematoxilin and eosin. We verified to be pathologically coexistent with a cavernous angioma and a focal cortical dysplasia. We also found unusual neurons that were accompanied by perineuronal glial satellitosis in the subcortical white matter, those were occasionally observed in epileptic foci and were thought to be a form of neuronal migration disorders.     

Learning and Memory Impairment in Patients with Temporal Lobe Epilepsy: Relation to the Presence, Type, and Location of Brain Lesion

PURPOSE: To study the influence of epileptogenic lesions on learning and memory alterations in patients with temporal lobe epilepsy (TLE). METHODS: We studied 131 patients (55 with left and 39 with right lesional TLE; 22 with left and 15 with right cryptogenic TLE) and 36 healthy subjects. We compared these groups by using a battery of tests to assess verbal and visual learning, delayed recall, and recall after the imposition of interfering activity. RESULTS: Compared with the controls and patients with right TLE, the patients with left TLE were significantly impaired on all verbal tests. On visual tests, patients with right TLE were impaired compared with controls but not more so than patients with left TLE. Separate multivariate analyses of variance (MA-NOVAs) of patients' verbal and visual test scores, taking the TLE side and morphologic features of the temporal lobes (i.e., normal, hippocampal sclerosis, low-grade glioma, or cavernous angioma) as independent factors, did not show any significant effect of these features. Separate comparisons of verbal and visual test scores of patients with lesional TLE, taking the side and location (mesial or lateral) of the epileptogenic lesion as independent factors, did not show any significant effect of location. CONCLUSIONS: Our findings show that some learning and memory abilities are impaired in patients with TLE irrespective of the presence of overt damage. This supports the theory that focal epileptic discharges, rather than the lesions themselves, affect these functions. The pathologic characteristics and intratemporal location of an associated lesion do not seem to play an important role in determining learning and memory impairment when clinical and treatment-related factors are taken into account.     

fMRI of triggerable aurae in musicogenic epilepsy

The authors studied a patient with musicogenic epilepsy triggered by one specific musical piece using 3D PRESTO fMRI. During epileptic aurae initiated by the stimulus, signal increases were found in the left anterior temporal lobe, correlating with ictal EEG and SPECT showing a left anterior temporal focus, and the right gyrus rectus. Because fMRI indicated a cascade of recruitment of the ventral frontal lobes by epileptogenic music, left anterior temporal lobe activity could be secondary to a right gyrus rectus focus, possibly triggered by emotional processing of music.     

Effects of unilateral temporal lobectomy on verbal dichotic listening test

Verbal dichotic listening test was conducted before and after anterior temporal lobectomy on 25 patients who underwent the operation because of their medication-resistant epileptic seizures. Their speech dominance by Wada test was all left sided. 1. Preoperatively, patients having the epileptogenic focus in the right temporal lobe (R-TLE) and those having the focus in the left (L-TLE) were, as expected, all right-ear dominant. The mean number of correct responses was fewer in L-TLE than in R-TLE group. 2. Postoperatively, no detrimental effects for recognition of verbal auditory stimuli by the ear contralateral to the focus was observed both in L-TLE and in R-TLE group. 3. Postoperatively, the ear-dominance shifted: to the left in patients with L-TLE, and to the right more conspicuously in patients with R-TLE compared to the preoperative scores. In other words, the recognition ability by the ears ipsilateral to the side of focus, or of resected temporal lobe, was ameliorated. Summarizing, the unilateral anterior temporal lobectomy did not cause "lesion effect" but yielded improvement of verbal auditory recognition by ears ipsilateral to the epileptogenic focus. Diminished epileptic bombardment resulted in by the resection surgery may be a possible explanation.     

An angiographically occult arteriovenous malformation in the medial parietal lobe presenting as seizures of medial temporal lobe origin

We present an unusual case of a patient who was diagnosed with temporal lobe epilepsy and whose seizures were reduced markedly after excision of an angiographically occult arteriovenous malformation (AVM) located in the left medial parietal lobe. A 38-year-old man had complex partial seizures characterized by motionless staring with oroalimentary and behavioral automatisms since the age of 15 years. Magnetic resonance imaging (MRI) demonstrated a small lesion extending from the left posterior cingulate gyrus to the precuneus. There was no MRI evidence of mesial temporal sclerosis. Intracranial EEG recordings showed ictal onset from the left medial parietal lobe propagating to the medial temporal lobes. Clinical signs appeared when these discharges reached the temporal lobes. After excision of the lesion (which was histologically confirmed as an AVM), together with the marginal cortex, seizures were reduced significantly. Careful diagnostic evaluation of lesions such as the this one may reveal an epileptogenic lesion (zone) far from the region where scalp ictal discharges seem to arise. In our case, we hypothesize that false localization was due to propagation of ictal discharges from the parietal focus through the limbic system.     

Lateralization of olfactory processing: Differential impact of right and left temporal lobe epilepsies

Olfactory processes were reported to be lateralized. The purpose of this study was to further explore this phenomenon and investigate the effect of the hemispheric localization of epileptogenic foci on olfactory deficits in patients with temporal lobe epilepsy (TLE). Olfactory functioning was assessed in 61 patients and 60 healthy control (HC) subjects. The patients and HC subjects were asked to rate the intensity, pleasantness, familiarity, and edibility of 12 common odorants and then identify them. Stimulations were delivered monorhinally in the nostril ipsilateral to the epileptogenic focus in TLE and arbitrarily in either the left or the right nostril in the HC subjects. The results demonstrated that regardless of the side of stimulation, patients with TLE had reduced performance in all olfactory tasks compared with the HC subjects. With regard to the side of the epileptogenic focus, patients with left TLE judged odors as less pleasant and had more difficulty with identification than patients with right TLE, underlining a privileged role of the left hemisphere in the emotional and semantic processing of odors. Finally, irrespective of group, a tendency towards a right-nostril advantage for judging odor familiarity was found in agreement with a prominent role of the right hemisphere in odor memory processing.     

Depression, anxiety, and temporal lobe epilepsy. Laterality of focus and symptoms

The association between anxiety, depression, and lateralization of an epileptogenic focus was explored in 18 adult patients with a left temporal lobe focus, 21 with a right focus, 20 with bilateral temporal foci, and 16 individuals with absence seizures. No significant difference in the level of anxiety was found among the groups. However, patients with left-sided temporal lobe epilepsy scored significantly higher than other groups on self-ratings for depression. This could not be accounted for by factors such as duration of epilepsy, employment status, education, age at seizure onset, or medication status. The left temporal lobe epilepsy group had a nonsignificantly larger number of males and left-handed subjects. The possible interactions between gender, handedness, seizure focus, and vulnerability to depression are described.     

Verbal learning and forgetting in patients with temporal lobe epilepsy

Studies comparing non-surgical patients with left or right temporal lobe epilepsy (TLE) have shown irregular differences in verbal learning and memory. We assessed the performance of unoperated patients with epileptogenic temporal lobe lesions or cryptogenic TLE using a selective reminding procedure for the learning of a word list, and five delayed trials for the recall of learned words. On the selective reminding procedure, patients with left TLE were found to be more impaired than those with right TLE and controls, in agreement with the role of the left temporal lobe in verbal learning. The patients with right TLE were more impaired than the controls, possibly due to the semantic organization of the word list The rate of forgetting learned words was similar in the patient and control groups, suggesting that patients with left TLE can normally retain and/or retrieve stored items. These data support the hypothesis that distinct functional systems subserve learning and memory. Comparisons of the patient subgroups with epileptogenic lesions (hippocampal sclerosis or low-grade glioma) and those with cryptogenic TLE did not reveal any significant difference in learning or in memory, suggesting that epileptiform activity could affect verbal performance as a detectable temporal lesion.     

Electroclinical and magnetoencephalographic analysis of epilepsy in patients with congenital bilateral perisylvian syndrome

PURPOSE: Epilepsies in four patients with congenital bilateral perisylvian syndrome (CBPS) were studied electroclinically and by magnetoencephalography (MEG) to determine whether cortical dysplasia associated with this syndrome is epileptogenic. METHODS: We studied three women and one man (mean +/- SD age 30.8 +/- 3.4 years) with a diagnosis of CBPS based on magnetic resonance imaging (MRI). All had drug-resistant epilepsy. In addition to electroclinical analysis, the distribution of equivalent-current dipoles (ECDs) analyzed from MEG signals was examined. RESULTS: Patient 1 had left-sided parietal lobe epilepsy and ECDs clustered in the left temporoparietal lobe. Patient 2 had bilateral, independent temporoparietal lobe epilepsy, and ECDs were found in both hemispheres, with clustering in the right temporoparietal lobe but not in the left hemisphere. Patient 3 presumably had parietal lobe epilepsy with unidentified focus side and ECDs clustered in the left parietal and right temporal lobes. Patient 4 had symptomatic generalized epilepsy, and ECDs were observed in both hemispheres without clustering. In the three patients who had partial epilepsy (patients 1-3), clusters of ECDs overlaid the perisylvian dysplasia and were not found elsewhere. CONCLUSIONS: Patients with CBPS may have either symptomatic partial epilepsy or symptomatic generalized epilepsy, and those with partial epilepsy are likely to have temporoparietal foci. In addition, cortical dysplasia is closely related to the generation of partial seizures and may be epileptogenic per se. However, this study did not elucidate the relationship between cortical dysplasia and CBPS-generated generalized epilepsy.     

术中高场强MRI辅助显微外科手术治疗颞叶癫痫

目的探讨应用术中高场强MRI辅助显微外科手术治疗颞叶癫痫的效果。方法2011年6月至2012年4月,对结构性异常的颞叶癫痫患者18例,利用1．5T高场强MRI实时辅助,术前术中常规行T、T2及T1加权、弥散张量成像检查,以确定显微手术切除范围及功能区。结果术后病检结果示右侧颞叶海绵状血管瘤2例,左侧颞叶海绵状血管瘤3例,右侧颞叶弥漫性少枝星形细胞瘤2例,左侧海马硬化4例,右侧海马硬化6例,左侧颞叶胚胎发育不良性神经上皮肿瘤1例。术后复查MRI手术切除满意,无手术并发症。术后随访2个月．1年,EngelⅠ级14例,Ⅱ级4例。结论术中1．5T高场强MRI辅助显微外科手术治疗结构性异常的颞叶癫痫,可以较完全切除致痫灶,并保护神经功能,手术安全和效果好。     

Singing can improve speech function in aphasics associated with intact right basal ganglia and preserve right temporal glucose metabolism: Implications for singing therapy indication

Clinically, we know that some aphasic patients can sing well despite their speech disturbances. Herein, we report 10 patients with non-fluent aphasia, of which half of the patients improved their speech function after singing training. We studied ten patients with non-fluent aphasia complaining of difficulty finding words. All had lesions in the left basal ganglia or temporal lobe. They selected the melodies they knew well, but which they could not sing. We made a new lyric with a familiar melody using words they could not name. The singing training using these new lyrics was performed for 30 minutes once a week for 10 weeks. Before and after the training, their speech functions were assessed by language tests. At baseline, 6 of them received positron emission tomography to evaluate glucose metabolism. Five patients exhibited improvements after intervention; all but one exhibited intact right basal ganglia and left temporal lobes, but all exhibited left basal ganglia lesions. Among them, three subjects exhibited preserved glucose metabolism in the right temporal lobe. We considered that patients who exhibit intact right basal ganglia and left temporal lobes, together with preserved right hemispheric glucose metabolism, might be an indication of the effectiveness of singing therapy.