MRI-negative Temporal Lobe Epilepsy: Is there a Role for PET?

MRI-negative PET-positive Temporal Lobe Epilepsy: A Distinct Surgically Remediable Syndrome Carne RP, O'Brien TJ, Kilpatrick CJ, MacGregor LR, Hicks RJ, Murphy MA, Bowden SC, Kaye AH, Cook MJ Brain 2004;127:2276–2285 Most patients with nonlesional temporal lobe epilepsy (NLTLE) will have the findings of hippocampal sclerosis (HS) on a high-resolution MRI. However, a significant minority of patients with NLTLE and electroclinically well-lateralized temporal lobe seizures have no evidence of HS on MRI. Many of these patients have concordant hypometabolism on fluorodeoxyglucose-PET ([18F]FDG-PET). The pathophysiologic basis of this latter group remains uncertain. We aimed to determine whether NLTLE without HS on MRI represents a variant of or a different clinicopathologic syndrome from that of NLTLE with HS on MRI. The clinical, EEG, [18F]FDG-PET, histopathologic, and surgical outcomes of 30 consecutive NLTLE patients with well-lateralized EEG but without HS on MRI (HS–ve TLE) were compared with 30 consecutive age- and sex-matched NLTLE patients with well-lateralized EEG with HS on MRI (HS+ve TLE). Both the HS+ve TLE group and the HS–ve TLE patients had a high degree of [18F]FDG-PET concordant lateralization (26 of 30 HS–ve TLE vs. 27 of 27 HS+ve TLE). HS–ve TLE patients had more widespread hypometabolism on [18F]FDG-PET by blinded visual analysis [odds ratio (OR,+∞(2.51,–); P = 0.001]. The HS–ve TLE group less frequently had a history of febrile convulsions [OR,0.077 (0.002 to 0.512), P = 0.002], more commonly had a delta rhythm at ictal onset [OR,3.67 (0.97 to 20.47); P = 0.057], and less frequently had histopathologic evidence of HS [OR,0 (0 to 0.85); P = 0.031]. No significant difference in surgical outcome despite half of those without HS having a hippocampal-sparing procedure. Based on the findings outlined, HS–ve PET-positive TLE may be a surgically remediable syndrome distinct from HS+ve TLE, with a pathophysiologic basis that primarily involves lateral temporal neocortical rather than mesial temporal structures.

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Intrinsic Thalamic Network in Temporal Lobe Epilepsy With Hippocampal Sclerosis According to Surgical Outcomes

Frontiers in Neurology ◽

10.3389/fneur.2021.721610 ◽

2021 ◽

Vol 12 ◽

Author(s):

Kyoo Ho Cho ◽

Ho-Joon Lee ◽

Kyoung Heo ◽

Sung Eun Kim ◽

Dong Ah Lee ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Surgical Outcomes ◽

Hippocampal Sclerosis ◽

Three Dimensional ◽

Thalamic Nuclei ◽

Characteristic Path Length ◽

Ipsilateral Hemisphere ◽

Hippocampal Subfields ◽

Significant Difference

Background: The aim of this study was to identify the differences of intrinsic amygdala, hippocampal, or thalamic networks according to surgical outcomes in temporal lobe epilepsy (TLE) patients with hippocampal sclerosis (HS).Methods: We enrolled 69 pathologically confirmed TLE patients with HS. All patients had pre-operative three-dimensional T1-weighted MRI using a 3.0 T scanner. We obtained the structural volumes of the amygdala nuclei, hippocampal subfields, and thalamic nuclei. Then, we investigated the intrinsic networks based on volumes of these structures using structural covariance and graph theoretical analysis.Results: Of the 69 TLE patients with HS, 21 patients (42.1%) had poor surgical outcomes, whereas 40 patients (57.9%) had good surgical outcomes. The volumes in the amygdala nuclei, hippocampal subfields, and thalamic nuclei were not different according to surgical outcome. In addition, the intrinsic amygdala and hippocampal networks were not different between the patients with poor and good surgical outcomes. However, there was a significant difference in the intrinsic thalamic network in the ipsilateral hemisphere between them. The eccentricity and small-worldness index were significantly increased, whereas the characteristic path length was decreased in the patients with poor surgical outcomes compared to those with good surgical outcomes.Conclusion: We successfully demonstrated significant differences in the intrinsic thalamic network in the ipsilateral hemisphere between TLE patients with HS with poor and good surgical outcomes. This result suggests that the pre-operative intrinsic thalamic network can be related with surgical outcomes in TLE patients with HS.

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Imaging Depression in Epilepsy: Hints at the Biology of Despair

Epilepsy Currents ◽

10.1111/j.1535-7511.2007.00199.x ◽

2007 ◽

Vol 7 (5) ◽

pp. 129-131

Author(s):

Paul A. Garcia

Keyword(s):

Major Depression ◽

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Hippocampal Sclerosis ◽

Morphological Characteristics ◽

Similar Degree ◽

P Value ◽

Depression Symptoms ◽

History Of ◽

Severity Of Depression

Major Depression in Temporal Lobe Epilepsy with Hippocampal Sclerosis: Clinical and Imaging Correlates. Briellmann RS, Hopwood MJ, Jackson GD. J Neurol Neurosurg Psychiatry 2007 Jan 26; [Epub ahead of print] PURPOSE: Refractory temporal lobe epilepsy (TLE) is often associated with hippocampal sclerosis (HS). Patients with Major Depression (MD) may also show structural abnormalities in the limbic system. Co-occurrence of TLE with HS and MD is not uncommon. We investigate clinical and morphological characteristics of TLE patients in relation to MD. METHODS: Thirty-four TLE patients with HS were assessed at a Comprehensive Epilepsy Program. All relevant clinical data were obtained, including the history of antecedent events to epilepsy. MD was diagnosed based on detailed psychiatric investigation. MRI was used to measure the volume and tissue signal (T2-relaxometry) of the hippocampus and amygdala. The imaging data were expressed as percentage of the values obtained in a series of 55 controls. RESULTS: A history of MD was present in 15 (44%) of the 34 patients. Patients with MD had a longer duration of their epilepsy ( p < 0.05), and a lower frequency of antecedent events (13% with MD, 58% without MD, p < 0.05). Both groups had a similar degree of ipsilateral HS (small hippocampal volume, increased hippocampal T2-relaxation time), and demonstrated bilateral amygdaloid atrophy. However, the contralateral amygdala showed lower signal in presence of MD (97 ± 9 msec; no MD: 103 ± 8 msec, ANCOVA, p < 0.05). CONCLUSION: The integrity of the amygdala may influence mood disturbances in TLE patients with HS, as depression was associated with a relative preservation of the contralateral amygdala. In contrast, hippocampal abnormalities were not related to the presence of depression. Hippocampal 1H-MRSI Correlates with Severity of Depression Symptoms in Temporal Lobe Epilepsy. Gilliam FG, Maton BM, Martin RC, Sawrie SM, Faught RE, Hugg JW, Viikinsalo M, Kuzniecky RI. Neurology 2007;68(5):364–368. OBJECTIVE: To investigate the association of an indicator of hippocampal function with severity of depression symptoms in temporal lobe epilepsy. METHODS: We evaluated 31 patients with video/EEG-confirmed temporal lobe epilepsy using creatine/ N-acetylaspartate ratio maps derived from a previously validated 1H magnetic resonance spectroscopic imaging (1H-MRSI) technique at 4.1 T. We also assessed depression symptoms, epilepsy-related factors, and self-perceived social and vocational disability. We used conservative nonparametric bivariate procedures to determine the correlation of severity of depression symptoms with imaging and clinical variables. RESULTS: The extent of hippocampal 1H-MRSI abnormalities correlated with severity of depression (Spearman rho = 0.65, p value < 0.001), but other clinical factors did not. CONCLUSION: The extent of hippocampal dysfunction is associated with depression symptoms in temporal lobe epilepsy and may be a more important factor than seizure frequency or degree of disability.

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Interleukin-1β secretion in hippocampal sclerosis patients with mesial temporal lobe epilepsy

Neurology International ◽

10.4081/ni.2013.e17 ◽

2013 ◽

Vol 5 (3) ◽

pp. 17 ◽

Cited By ~ 4

Author(s):

Nihal Olgac Dundar ◽

Berrin Aktekin ◽

Nilufer Cicek Ekinci ◽

Duygu Sahinturk ◽

Ugur Yavuzer ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Promoter Region ◽

Mononuclear Cells ◽

Hippocampal Sclerosis ◽

Intractable Epilepsy ◽

Mesial Temporal Lobe Epilepsy ◽

Epilepsy Syndrome ◽

Significant Difference ◽

Mesial Temporal Lobe

Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is a common medically intractable epilepsy syndrome. Although pathogenesis of HS still remains highly controversial, genetics may play a role as a predisposing factor. Previous evidence in a Japanese population revealed that the homozygotes for allele T at position −511 of the interleukin (IL)-1β gene promoter region (IL-1β-511 T/T) confers susceptibility to the development of HS. However, whether this polymorphism has an effect on IL-1β levels in MTLE-HS patients was not demonstrated. This study aimed to analyze the distribution of this particular polymorphism in a group of Turkish HS patients and correlate the polymorphism with IL-1β secretion from the lymphocytes, thus revealing a functional role for IL-1β in the etiopathogenesis of HS. A single base pair polymorphism at position −511 in the promoter region of the IL-1β gene was analyzed. The spontaneous and 1 ng/mL lipopolysaccharide-stimulated production of IL-1β by peripheral blood mononuclear cells after 4 and 24 h of incubation were measured by ELISA method. The heterozygous type (−511 C/T) was the most common genotype. There was no difference in frequency of allele −511 T between patients and controls. Analysis of IL-1β levels, genotype and allele distributions showed no significant difference among the groups (P>0.05). Nevertheless, it was seen that patients who carry a T allele at position -511 of the IL-1β gene had increased IL-1β levels. T-allele carriage may be important. Only IL-1β secretion from the lymphocytes has been assessed in this study. Considering the importance of IL-1β in the etiopathogenesis of HS, further studies are needed to evaluate locally produced IL-1β levels.

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Correlations of interictal FDG-PET metabolism and ictal SPECT perfusion changes in human temporal lobe epilepsy with hippocampal sclerosis

NeuroImage ◽

10.1016/j.neuroimage.2006.04.185 ◽

2006 ◽

Vol 32 (2) ◽

pp. 684-695 ◽

Cited By ~ 88

Author(s):

N. Nelissen ◽

W. Van Paesschen ◽

K. Baete ◽

K. Van Laere ◽

A. Palmini ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Fdg Pet ◽

Hippocampal Sclerosis ◽

Ictal Spect ◽

Human Temporal Lobe

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18F-FDG-PET patterns of surgical success and failure in mesial temporal lobe epilepsy

Neurology ◽

10.1212/wnl.0000000000003714 ◽

2017 ◽

Vol 88 (11) ◽

pp. 1045-1053 ◽

Cited By ~ 28

Author(s):

Francine Chassoux ◽

Eric Artiges ◽

Franck Semah ◽

Agathe Laurent ◽

Elisabeth Landré ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Fdg Pet ◽

Hippocampal Sclerosis ◽

Statistical Parametric Mapping ◽

Mesial Temporal Lobe Epilepsy ◽

Epileptogenic Zone ◽

Metabolic Pattern ◽

Suboptimal Outcome ◽

Mesial Temporal Lobe

Objective:To search for [18F]-fluorodeoxyglucose (FDG)-PET patterns predictive of long-term prognosis in surgery for drug-resistant mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis (HS).Methods:We analyzed metabolic data with [18F]-FDG-PET in 97 patients with MTLE (53 female participants; age range 15–56 years) with unilateral HS (50 left) and compared the metabolic patterns, electroclinical features, and structural atrophy on MRI in patients with the best outcome after anteromesial temporal resection (Engel class IA, completely seizure-free) to those with a non-IA outcome, including suboptimal outcome and failure. Imaging processing was performed with statistical parametric mapping (SPM5).Results:With a mean follow-up of >6 years (range 2–14 years), 85% of patients achieved a class I outcome, including 45% in class IA. Class IA outcome was associated with a focal anteromesial temporal hypometabolism, whereas non-IA outcome correlated with extratemporal metabolic changes that differed according to the lateralization: ipsilateral mesial frontal and perisylvian hypometabolism in right HS and contralateral fronto-insular hypometabolism and posterior white matter hypermetabolism in left HS. Suboptimal outcome presented a metabolic pattern similar to the best outcome but with a larger involvement of extratemporal areas, including the contralateral side in left HS. Failure was characterized by a mild temporal involvement sparing the hippocampus and relatively high extratemporal hypometabolism on both sides. These findings were concordant with electroclinical features reflecting the organization of the epileptogenic zone but were independent of the structural abnormalities detected on MRI.Conclusions:[18F]-FDG-PET patterns help refine the prognostic factors in MTLE and should be implemented in predictive models for epilepsy surgery.

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Determination of the Initial Abnormal Discharge Site in Temporal Lobe Epilepsy Through Combined EEG and Neuroimaging. What Is Next?

Frontiers in Neurology ◽

10.3389/fneur.2021.798228 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ana A. Rentería-Palomo ◽

Jose L. Montes-Ochoa ◽

Adriana Martinez-Mayorga ◽

Jorge Guillermo Reyes-Vaca ◽

Ildefonso Rodríguez-Leyva

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Latin American ◽

Epilepsy Surgery ◽

Comprehensive Evaluation ◽

Hippocampal Sclerosis ◽

Hippocampal Atrophy ◽

Significant Difference ◽

The Relationship

Objective: The objective of this study was to determine the relationship between atrophy of the hippocampus and severity of epilepsy in patients with temporal lobe epilepsy (TLE) as the first step to evaluate the possibility of surgery for epilepsy and analyze why patients cannot undergo epilepsy surgery.Methods: Volumetric MRI of the hippocampus was performed in 51 consecutive patients (29 men; mean age 40) with TLE. TLE diagnosis, lateralization, and severity (mild, moderate, severe) of seizures were based on a comprehensive evaluation that included neurologic examination and EEG in all patients. Patients with evidence of a lesion other than hippocampal sclerosis were not included in the study. We assessed the relationship between hippocampal volumes and electrophysiological evidence of seizure severity.Results: According to the affected side based on the EEG, a statistically significant difference (p < 0.001) in volume and a positive correlation between epilepsy and hippocampal atrophy were found.Conclusion: Our results confirm that volume loss to the hippocampus in patients with TLE correlates with the severity of epilepsy based on the EEG. Therefore, surgical treatment is considered early when hippocampal atrophy is evident in patients with refractory TLE. However, in Latin American countries, it is a challenge to get a patient to undergo epilepsy surgery. Therefore, we try to analyze the sad situation in our hospital.

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Pre- and post-operative Wisconsin card sorting test performance in patients with temporal lobe epilepsy due to hippocampal sclerosis

Dementia & Neuropsychologia ◽

10.1590/s1980-57642008dn10200010 ◽

2007 ◽

Vol 1 (2) ◽

pp. 173-180 ◽

Cited By ~ 3

Author(s):

Luciana Tisser ◽

Andre Palmini ◽

Eliseu Paglioli ◽

Mirna Portuguez ◽

Ney Azambuja ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Test Performance ◽

Hippocampal Sclerosis ◽

Executive Dysfunction ◽

Wisconsin Card Sorting Test ◽

Card Sorting ◽

Neuropsychological Profile ◽

Temporal Structures ◽

Sorting Test

Abstract Patients with temporal lobe epilepsy due to hippocampal sclerosis (TLE/HS) have a distinct neuropsychological profile, but there is still debate on whether executive dysfunction is part of this profile and also whether temporal lobe surgery can modify this dysfunction. Objective: To study the presence and reversibility of executive dysfunction in patients with unilateral TLE/HS. Methods: Twenty-five patients with refractory seizures due to TLE/HS underwent presurgical evaluation which included the application of the Wiconsin Card Sorting Test (WCST). Nineteen were re-evaluated in follow up, at least 6 months after selective amygdalo-hippocampectomy (SAH). Twenty-two control subjects matched for age and education also performed the WCST. Results: Sixteen of the 25 patients (64%) completed fewer than four categories in the WCST whereas only 4 of the 22 controls (18%) did not complete at least four categories (p<0.005). In addition, the performance of the patients involved significantly more perseverative responses and errors compared to controls. The patient group demonstrated significant post-operative improvement in many measures of the WCST following SAH. Conclusions: These findings support the presence of executive dysfunction in patients with TLE/HS and suggest that such dysfunction can be partially reversed by selective resection of epileptogenic mesial temporal structures.

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Association of hypometabolic extension of 18F-FDG PET with diffusion tensor imaging indices in mesial temporal lobe epilepsy with hippocampal sclerosis

Seizure ◽

10.1016/j.seizure.2021.04.007 ◽

2021 ◽

Vol 88 ◽

pp. 130-137

Author(s):

Hiroyuki Tatekawa ◽

Hiroyuki Uetani ◽

Akifumi Hagiwara ◽

Masatoshi Hotta ◽

John M. Stern ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Fdg Pet ◽

Diffusion Tensor ◽

Hippocampal Sclerosis ◽

Mesial Temporal Lobe Epilepsy ◽

Mesial Temporal Lobe ◽

18F Fdg

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Abnormalities of Cortical Thickness in Pediatric Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis

Current Medical Imaging Formerly Current Medical Imaging Reviews ◽

10.2174/1573405616666200116161335 ◽

2020 ◽

Vol 16 (9) ◽

pp. 1095-1104

Author(s):

Kan Deng ◽

Rushi Zou ◽

Bingsheng Huang ◽

Ping Zeng ◽

Dong Liang ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Cortical Thickness ◽

Parietal Lobe ◽

Hippocampal Sclerosis ◽

Mesial Temporal Lobe Epilepsy ◽

Precentral Gyrus ◽

Significant Difference ◽

Mesial Temporal Lobe ◽

And Gender

Objective: Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is the most common intractable seizure type of pediatric epilepsy, with alterations in the cortex across the whole brain. The aim of this study is to investigate the abnormalities of cortical thickness in pediatric MTLE-HS. Methods: Subjects were recruited from Shenzhen Children’s Hospital between September 2015 and December 2016. MTLE was confirmed by the experienced neurological physician based on International League Against Epilepsy (ILAE) diagnosis criteria, and structural magnetic resonance imaging (MRI) was performed at 3T for quantitative assessment of cortical thickness. A general linear model with age and gender as covariates was used to examine the vertex-wise differences in cortical thickness between 1) left MTLE-HS (LMTLE-HS) and healthy controls (HC), and 2) right MTLE-HS (RMTLE-HS) and HC. The family-wise error corrected significance threshold was set at P < 0.05. Through a combination of probability and cluster-size thresholding, cluster-wise P values were obtained for the resulting clusters. Results: 13 LMTLE-HS, 6 RMTLE-HS, and 20 age-matched HC were finally enrolled in the study. No significant difference in the mean age (LMTLE-HS vs. HC, p=0.57; RMTLE-HS vs. HC, p=0.39) and gender ratio (LMTLE-HS vs. HC, p=0.24; RMTLE-HS vs. HC, p=0.72) was found between MTLE-HS and HC. In LMTLE-HS, cortical thickness was found significantly decreased in the ipsilateral caudal middle frontal gyrus (p=0.012) and increased in the contralateral inferior temporal gyrus (p=0.020). In RMTLE-HS, cortical thickness significantly decreased in the ipsilateral posterior parietal lobe (superior, p<0.001 and inferior parietal gyrus, p=0.03), the anterior parietal lobe (postcentral gyrus, p=0.006), the posterior frontal lobe (precentral gyrus, p=0.04 and the lateral occipital gyrus, p<0.001), and the contralateral lateral occipital gyrus, middle frontal (p<0.0001) and superior frontal gyrus (p<0.001), and pericalcarine cortex (p=0.020). Conclusion: We detected significant cortical abnormalities in pediatric MTLE-HS patients compared with HC. These cortical abnormalities could be explained by specific pathogenesis in MTLE-HS, and may finally contribute to understanding the intrinsic mechanism of MTLE-HS.

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