Reorganized cerebral metabolic interactions in temporal lobe epilepsy.

Patients with left temporal lobe epilepsy demonstrate language impairments that are not well understood. To explore abnormal patterns of brain functional connections with respect to language processing, we applied a principal component analysis to resting regional cerebral metabolic data obtained with positron emission tomography in patients with right- and left-sided temporal lobe epilepsy and controls. Two principal components were expressed differentially among the groups. One principal component comprised a pattern of metabolic interactions involving left inferior frontal and left superior temporal regions-corresponding to Broca's and Wernicke's areas, respectively-and right mesial temporal cortex and right thalamus. Functional couplings between these brain regions were abnormally enhanced in the left-sided epilepsy patients. The right thalamic left superior temporal coupling was also abnormally enhanced in the right-sided epilepsy patients, but differentially from that in the left-sided patients. The other principal component was characterized by a pattern of metabolic interactions involving right and left mid prefrontal and right superior temporal cortex. Although both the right- and left-sided epilepsy patients showed decreased functional couplings between left mid prefrontal and the other brain regions, a weaker right-left mid prefrontal coupling in the left-sided epilepsy patients best distinguished them from the right-sided patients. The two mutually independent, abnormal metabolic patterns each predicted verbal intelligence deficits in the patients. The findings suggest a site-dependent reorganization of two independent, language-subserving pathways in temporal lobe epilepsy.     

Diffusion tensor analysis of temporal and extra-temporal lobe tracts in temporal lobe epilepsy

OBJECTIVE: To determine whether the major temporal lobe white matter tracts in patients with temporal lobe epilepsy manifest abnormal water diffusion properties. METHODS: Diffusion tensor MRI measurements were obtained from tractography for uncinate, arcuate, inferior longitudinal fasciculi and corticospinal tract in 13 children with left temporal lobe epilepsy and normal conventional MRI, and the data were compared to measurements in 12 age-matched normal volunteers. The relationship between tensor parameters and duration of epilepsy was also determined. RESULTS: All four tracts in the affected left hemisphere showed lower mean anisotropy, planar and linear indices, but higher spherical index in patients versus controls. Diffusion changes in the left uncinate and arcuate fasciculus correlated significantly with duration of epilepsy. Arcuate fasciculus showed a reversal of the normal left-right asymmetry. Various diffusion abnormalities were also seen in the four tracts studied in the right hemisphere. CONCLUSION: Our findings indicate abnormal water diffusion in temporal lobe and extra-temporal lobe tracts with robust changes in the direction perpendicular to the axons. Diffusion abnormalities associated with duration of epilepsy suggest progressive changes in ipsilateral uncinate and arcuate fasciculus due to chronic seizure activity. Finally, our results in arcuate fasciculus are consistent with language reorganization to the contralateral right hemisphere.     

Verbal memory encoding in patients with left-sided hippocampal sclerosis

Patients with medial temporal lobe epilepsy based on left hippocampal sclerosis often show severe verbal memory deficits. Recent studies suggest that memory formation in these patients may be reallocated to the right hemisphere owing to left hippocampal pathology. To test this hypothesis, we used functional magnetic resonance imaging to examine encoding-related activity of verbal items in temporal lobe epilepsy patients with left hippocampal sclerosis and patients with idiopathic epilepsy as a control group. Results demonstrated that patients with idiopathic epilepsy showed more activation in both left and right hippocampi. The temporal lobe epilepsy group showed enhanced activation in left fusiform gyrus. We discuss these results in terms of different strategy use by the groups.     

难治性癫癎MRJ颞极信号特点与癫癎的相关性分析

目的探讨难治性癫癎MRI颞极信号特点与致癎区相关性。方法回顾性分析339例难治性癫癎病人MRI颞极信号特点。根据癫癎发作起始区将研究对象分为颞叶癫癎、额叶癫癎、顶叶癫癎、枕叶癫癎、岛叶癫癎、多脑叶癫癎等6类。结果颞极信号异常187例,颞极信号异常侧别与致癎区侧别一致率达98．93％,颞极信号异常与癫癎类型或致癎区有关（χ2=311．339,P〈0．001）。与颞叶外癫癎比较,颢极信号异常更常见于颞叶癫癎。结论在各类癫癎中均可出现MR／颞极信号异常,但更常见于颞叶癫癎。颞极信号异常侧常与致癎区侧别一致．特别是颞叶癫癎。     

Contralateral medial temporal lobe damage in right but not left temporal lobe epilepsy: a (1)H magnetic resonance spectroscopy study

BACKGROUND: Proton magnetic resonance spectroscopy (MRS) of the hippocampus is useful in lateralising the epileptic focus in temporal lobe epilepsy for subsequent surgical resection. Previous studies have reported abnormal contralateral MRS values in up to 50% of the patients. OBJECTIVE: To identify the contributing factors to contralateral damage, as determined by MRS, and its extension in patients with temporal lobe epilepsy. METHODS: Single voxel MRS was carried out in the hippocampus and lateral temporal neocortex of both hemispheres in 13 patients with left temporal lobe epilepsy (LTLE) and 16 patients with right temporal lobe epilepsy (RTLE). All patients had mesial temporal lobe epilepsy with hippocampal sclerosis. Controls were 21 healthy volunteers of comparable age. RESULTS: Consistent with previous studies, the NAA/(Cho+Cr) ratio was abnormally low in the hippocampus ipsilateral to the focus (p < 0.0001), and there were lower values in both patient groups in the ipsilateral temporal neocortex (p < 0.0001). Patients with RTLE had left hippocampal MRS anomalies (p = 0.0018), whereas the right hippocampus seemed to be undamaged in LTLE patients. CONCLUSIONS: Unilateral mesial temporal lobe epilepsy is associated with widespread metabolic abnormalities which involve contralateral mesial and neocortical temporal lobe structures. These abnormalities appear to be more pronounced in patients with RTLE.     

Mesial temporal lobe abnormalities in a family with 15q26qter trisomy

BACKGROUND: The association of chromosomal imbalances and neurologic abnormalities is well known. OBJECTIVE: To describe a family with 2 brothers presenting with 15q trisomy due to a maternal equilibrated translocation involving chromosomes 12 and 15. DESIGN, SETTING, AND PATIENTS: Among patients with epilepsy followed up in our hospital, we identified 2 brothers with epilepsy and mental retardation who presented dysmorphic features. Detailed clinical, electroencephalographic, and magnetic resonance imaging investigation was performed. In addition, we collected blood samples for karyotyping. RESULTS: Clinical findings included minor dysmorphic features, mental retardation, abnormal behavior, and secondary generalized epilepsy. Electroencephalography showed left temporal slow waves in the older brother and background abnormality associated with generalized and multifocal epileptiform discharges in the other. Their magnetic resonance images showed mesial temporal lobe malformation, including the hippocampus and parahippocampal and fusiform gyri, with abnormal shape and axis. CONCLUSIONS: To our knowledge, this is the first report of mesial temporal lobe malformation associated with chromosomal abnormalities. Our finding may contribute to the understanding of the genetic mechanisms involved in central nervous system malformations, especially in the mesial temporal lobe structures.     

Sprachdiagnostik bei Patienten mit unilateraler Temporallappenepilepsie

Background

Deficits in visual confrontation naming ability constitute a typical deficit in patients with left temporal lobe epilepsy.

Patients and methods

Naming function was assessed in 106 patients with temporal lobe epilepsy (left: 58, right: 48) and left hemispheric language representation and in 74 healthy volunteers.

Results

Focus localization was improved with application of the Boston Naming Test. Patients with left and right temporal lobe epilepsy showed significantly worse naming performance compared to controls (p<0.01). Naming performance of patients with left temporal lobe epilepsy was significantly worse compared to patients with right temporal lobe epilepsy (p<0.01). Regression analysis revealed focus localization and verbal intelligence as the most important predictors for naming performance. Naming deficit ≥17.5% was specifically found in patients with left temporal lobe epilepsy and verbal intelligence level lower than average.

Conclusion

Our results suggest that the left temporal lobe plays a specific role for controlling speech-related processing of visually perceived objects. Therefore, dysnomia in left temporal lobe epilepsy reflects a deficit in the accurate semantic and/or phonological interpretation of visual information.     

难治性癫痫患者脑网络介数及其异常脑区间功能连接变化研究

目的基于图论的分析方法了解难治性癫痫患者脑功能网络介数属性变化,探讨介数异常脑区间功能连接改变的意义。方法采集难治性癫痫患者及健康被试RS-f MRI数据后,通过Gretna中Network Analysis模块预处理并计算出各脑区的介数值,经统计检验找出介数值有差异脑区;运用REST软件将上述脑区作为ROI两两之间做功能连接,经统计检验后找出脑区间差异的连接。结果与对照组相比,癫痫组介数值升高的脑区有右侧额下回三角部、右侧嗅皮质;介数值下降的脑区有右侧额上回背外侧、左侧额上回眶部、左侧前扣带回、右侧颞上回、右侧颞下回;与健康被试相比,额下回三角部与颞上回之间的连接降低。结论难治性癫痫患者脑功能网络介数属性及异常脑区间的功能连接改变,引起脑区间信息交流的障碍,可能导致癫痫患者认知功能的损伤。     

Mesial temporal lobe epilepsy with lateral temporal lobe abnormalities in magnetoencephalography and glucose metabolism.

Magnetoencephalography (MEG) and positron emission tomography (PET) revealed abnormal findings in the lateral temporal lobe of a 22 year old female with mesial temporal lobe epilepsy. Electroencephalography identified the epileptogenic focus in the left mesial temporal lobe and standard anterior temporal lobectomy resulted in a good surgical outcome. These discrepancies can be explained by the presence of anatomical and functional pathways between the mesial and lateral temporal structures, or pathophysiological abnormalities in both the mesial and lateral temporal lobes. Careful evaluation is necessary for analysis of MEG and PET findings in patients with temporal lobe epilepsy.     

Deficit in memory consolidation (abnormal forgetting rate) in childhood temporal lobe epilepsy. Pre and postoperative long-term observation

Deficits in memory consolidation have been reported in adult patients with epilepsy but, not to our knowledge, in children. We report the long-term follow-up (9 y. o. to 18 y. o.) of a boy who suffered from temporal lobe epilepsy and underwent a left temporal lobectomy with amygdalo-hippocampal resection at the age of 10. He showed an abnormal forgetting rate when trying to encode new information and a significant deficit for retrieving remote episodic memories (when compared with his twin brother), both consistent with a consolidation disorder. His memory condition slightly improved after cessation of the epilepsy, nevertheless did not normalize. No standard memory assessment could pinpoint his memory problem, hence an adapted methodology was needed. We discuss the nature of the memory deficit, its possible causes and its clinical implications.     

The effect of right temporal lobe lesions on matching of smells

Thirty patients with bitemporal lobe epilepsy, 14 patients with right temporal lobe epilepsy, 14 patients with left temporal lobe epilepsy, 14 patients who had right temporal lobectomy, 10 patients who had left temporal lobectomy and 12 patients who had lobectomy involving frontal or fronto-parietal regions were tested for their ability to match smells. A simple matching technique was used. It was found that patients with right temporal lobe lesions had difficulty in matching smells. There was no significant difference between the right temporal lobe epilepsy group and the right temporal lobectomy group. The implications of these findings are discussed.     

Explicit and implicit emotional processing modifications in pharmacoresistant left temporal lobe epilepsy and anxiodepressive disorders

We examined whether anxiodepressive patients with left temporal lobe epilepsy could be differentiated from those with depression but without epilepsy on tasks that investigate attentional bias toward and explicit judgment of emotional stimuli. Eight depressive patients, eight anxiodepressive patients with epilepsy, and eight controls participated in the present study. Anxiodepressive with epilepsy and depressive patients had comparable depression scores and the same cognitive profile. Two distinct emotional tasks were used: the decision lexical task and the number comparison task. Three emotional connotations were presented: neutral, positive, and negative. The pattern of results showed an attentional bias toward negative words and pictures in depressive patients and only toward negative words in anxiodepressive patients with epilepsy. Moreover, depressive patients explicitly judged negative stimuli with lower intensity and anxiodepressive patients judged neutral stimuli with higher intensity. The present study specifies the emotional functioning in depression with or without left temporal lobe epilepsy.     

Compromised memory function in schizophrenia and temporal lobe epilepsy

The purpose of this study was to investigate compromised memory function of schizophrenia patients in comparison with temporal lobe epilepsy patients, whose memory impairments result from a clear lesion. The authors hypothesized that schizophrenia patients would show poorer immediate and delayed recall performances in verbal and visual memory tasks. The study sample consisted of a healthy comparison group of 30 subjects and three patient groups comprising 76 schizophrenia patients, 93 left temporal lobe epilepsy patients, and 72 right temporal lobe epilepsy patients. The authors assessed immediate recall, delayed recall, and delayed retention. Tasks were subdivided into two categories (easy and difficult), and then patient memory dysfunction was compared among the memory tests. The authors observed material-specific memory impairment, where the left temporal lobe epilepsy group showed severe verbal memory impairment and the right temporal lobe epilepsy group showed severe visual memory impairment. A moderate impairment was found in immediate and delayed verbal memory in schizophrenia patients, and the impairment of visual memory was amplified with delayed recall. Such a result can be interpreted not only as a generalized cognitive deficit, but also as an integrative dysfunction involving the mesial temporal and frontal lobes in the left and right hemispheres, whereby the lesion site cannot be determined selectively. Our results show that the selection of a memory task that cannot be influenced by verbal mediation is very important for analyzing memory dysfunction in schizophrenia patients.     

Postoperative speech processing in temporal lobe epilepsy: Functional relationship between object naming,semantics and phonology

Deficits in confrontation naming ability can occur after epilepsy surgery in the left temporal lobe. This study addresses the functional relationship between postoperative object naming and semantic and phonological speech processing in patients with epilepsy. Fifty-eight consecutive patients with temporal lobe epilepsy from our epilepsy surgery program (24 patients with left temporal lobe epilepsy, 34 patients with right temporal lobe epilepsy) were investigated using the Boston Naming Test and comprehensive semantic and phonological speech testing. Language dominance was evaluated in all patients with the preoperative intracarotid sodium amytal test. Naming decline was observed exclusively in patients with left temporal lobe epilepsy. Regression analysis with semantic processing and phonological input/output processing as independent variables, and naming change in the Boston Naming Test (preoperative–postoperative score) as a dependent variable, revealed a significant association between postoperative naming decline and impaired semantic functions. Accordingly, patients exhibited deficits in the category-related differentiation of objects. It is hypothesized that naming deficits arise from the functional specialization of the left temporal lobe for semantic interpretation of visual input.     

Bilateral mesial temporal lobe epilepsy: comparison of scalp EEG and hippocampal MRI-T2 relaxometry

OBJECTIVE: Bilateral hippocampal abnormality is frequent in mesial temporal lobe sclerosis and might affect outcome in epilepsy surgery. The objective of this study was to compare the lateralization of interictal and ictal scalp EEG with MRI T2 relaxometry. MATERIAL AND METHODS: Forty-nine consecutive patients with intractable mesial temporal lobe epilepsy (MTLE) were studied with scalp EEG/video monitoring and MRI T2 relaxometry. RESULTS: Bilateral prolongation of hippocampal T2 time was significantly associated with following bitemporal scalp EEG changes: (i) in ictal EEG left and right temporal EEG seizure onsets in different seizures, or, after regionalized EEG onset, evolution of an independent ictal EEG over the contralateral temporal lobe (left and right temporal asynchronous frequencies or lateralization switch; P = 0.002); (ii) in interictal EEG both left and right temporal interictal slowing (P = 0.007). Bitemporal T2 changes were not, however, associated with bitemporal interictal epileptiform discharges (IED). Lateralization of bilateral asymmetric or unilateral abnormal T2 findings were associated with initial regionalization of the ictal EEG in all but one patient (P < 0.005), with lateralization of IED in all patients (P < 0.005), and with scalp EEG slowing in 28 (82,4%) of 34 patients (P = 0.007). CONCLUSION: Our data suggest that EEG seizure propagation is more closely related to hippocampal T2 abnormalities than IED. Interictal and ictal scalp EEG, including the recognition of ictal propagation patterns, and MRI T2 relaxometry can help to identify patients with bitemporal damage in MTLE. Further studies are needed to estimate the impact of bilateral EEG and MRI abnormal findings on the surgical outcome.     

Extratemporal atrophy in patients with complex partial seizures of left temporal origin

Total cerebral, temporal lobe, hippocampal, caudate, and lenticular nuclei volumes were quantified from magnetic resonance images of 21 patients with left temporal lobe epilepsy and medically intractable complex partial seizures. These regional brain volumes were compared with the same measures in 19 controls. No significant differences in total cerebral, left temporal lobe, right temporal lobe, or total temporal lobe volumes were found. As expected, left hippocampal volumes were significantly smaller in the patients with epilepsy than in control subjects. The left hippocampus-to-right hippocampus volume ratio was significantly lower in patients than in control subjects. In addition to left hippocampal volumes, mean left thalamic, left caudate, and bilateral lenticular volumes were significantly smaller in the patients with epilepsy than in control subjects. The left-to-right thalamic volume ratio was also significantly lower in the patients with epilepsy compared with control subjects, but there were no significant group differences in caudate or lenticular ratios. These results show that medically intractable temporal lobe epilepsy is associated with volume loss in brain structures outside the presumably involved hippocampus. The pathophysiological significance of our findings is uncertain. They could be related to the underlying cause of the disorder. However, volume loss also may reflect damage due to involvement of these structures in recurrent seizure activity.     

伴海马硬化的颞叶癫痫患者的临床特点分析

目的通过比较伴和不伴海马硬化的颞叶癫痫患者的临床特点,为临床诊治提供依据。方法收集2009年6月至2012年6月期间南京军区南京总医院颞叶癫痫患者144例,通过头颅MRI或颞叶癫痫手术病理分类,对每位患者发作时临床表现、发作间期、起病年龄及脑电图等进行分析。结果伴海马硬化的颞叶癫痫患者起病年龄较不伴海马硬化的颞叶癫痫患者更小,同时更易出现发作前先兆和意识障碍。伴或不伴海马硬化的颞叶癫痫患者的脑电图异常率相似,大多数患者脑电图可发现癫痫样异常改变。海马硬化患者有高热惊厥史的更常见。结论伴有海马硬化的颞叶癫痫患者有一些特殊的临床表现,深入了解伴海马硬化的颞叶癫痫患者的临床特点将利于更好更快地选择颞叶癫痫患者的合理治疗方案。     

Surgically proven coexistence of focal and generalized epilepsy: A case report

The coexistence of focal and idiopathic generalized epilepsy (IGE) is rarely observed, and the mechanism underlying this situation remains unknown. We report a 13-year-old girl with well-controlled generalized epilepsy and medically-refractory left temporal lobe epilepsy.She underwent intracranial EEG recording, which demonstrated two characteristic seizure patterns of generalized ictal onset and left mesial temporal onset. In addition, two types of interictal spike distribution, including the left mesial temporal region and generalized spikes, were also supportive of the coexistence of left mesial temporal lobe epilepsy and IGE. Thereafter, a left anterior temporal lobectomy and post-surgical medication significantly improved her seizure outcome. This case illustrates the importance of considering surgical management for patients with medically-intractable focal epilepsy coexisting with generalized epilepsy.     

Interaction of cognitive aging and memory deficits related to epilepsy surgery

Temporal lobe epilepsy surgery can cause significant memory impairment. This study was intended to examine whether surgery also could affect prognosis of memory in older age. Age regression of verbal memory was examined in 187 patients (before and 1 year after left temporal lobe surgery) and 264 healthy controls. Eighty patients underwent selective amygdalohippocampectomy, and 107 patients underwent anterior two-thirds temporal lobectomy. Amygdalohippocampectomy patients had mesiotemporal epilepsy; anterior two-thirds temporal lobectomy patients had more extramesial or diffuse seizure onset zones. Memory was assessed by word list learning for its more mesial (consolidation/retrieval) and more neocortical (learning) aspects. Patients showed significant preoperative memory impairment. Independent of seizure outcome and surgical approach, surgery had significant negative effects on learning and consolidation/retrieval. In the amygdalohippocampectomy group, preoperative and postoperative age regressions of learning and consolidation/retrieval were not different from those of controls. In the anterior two-thirds temporal lobectomy group, age regression of verbal learning became steeper after surgery, and consolidation/retrieval was negatively correlated with older age and later onset of epilepsy even before surgery. The data confirm that age regression of verbal memory in left temporal lobe epilepsy is similar to that in healthy controls. Both left anterior two-thirds temporal lobectomy and amygdalohippocampectomy worsen verbal learning and memory and bring patients closer to cognitive disability. Particularly in anterior two-thirds temporal lobectomy patients, surgery and reduced capacities for compensation cause acceleration of lifetime memory decline. The results support earlier and tailored epilepsy surgery and suggest that memory prognosis in older age should be considered if more extensive temporal resections would be inevitable.     

Semantic memory impairment in temporal lobe epilepsy associated with hippocampal sclerosis

Episodic memory impairment is a well-recognized feature of mesial temporal lobe epilepsy. Semantic memory has received much less attention in this patient population. In this study, semantic memory aspects (word-picture matching, word definition, confrontation and responsive naming, and word list generation) in 19 patients with left and right temporal lobe epilepsy secondary to mesial temporal sclerosis (MTS) were compared with those of normal controls. Patients with LMTS showed impaired performance in word definition (compared to controls and RMTS) and in responsive naming (compared to controls). RMTS and LMTS patients performed worse than controls in word-picture matching. Both patients with left and right mesial temporal lobe epilepsy performed worse than controls in word list generation and in confrontation naming tests. Attentional-executive dysfunction may have contributed to these deficits. We conclude that patients with left and right MTS display impaired aspects of semantic knowledge. A better understanding of semantic processing difficulties in these patients will provide better insight into the difficulties with activities of daily living in this patient population.