Seizure outcome in surgically treated drug-resistant mesial temporal lobe epilepsy based on the recent histopathological classifications

Abstract

D rug-resistant MTLE is the most common type of epilepsy requiring surgical treatment, with a favorable seizure outcome being achieved in about 60%-75% of patients. 50,51,64,82,89 Clinically, MTLE is often regarded as a relatively homogeneous syndromic entity, with seizures characterized by typical ictal semiology 32,96 and EEG findings. 29,96 However, a variety of MTLE subtypes have been described according to the underlying etiology, with different surgical prognoses. 47,89,92 Recent neuropathological classifications of epi lep to gen ic lesions, such as mesial temporal sclerosis (MTS), 11 granule cell pathology (GCP), 10 focal cortical dysplasia (FCD), 12 and epilepsy-associated low-grade tumor (ELGT) 1,54,55,73,74,91 Object. The study was performed to investigate the relation between seizure outcome after surgical treatment of mesial temporal lobe epilepsy (MTLE) and pathological findings, classified according to the recently proposed classifications of mesial temporal sclerosis (MTS), granule cell pathology (GCP), focal cortical dysplasia (FCD) and epilepsy-associated low-grade tumors (ELGT).Methods. The authors analyzed data obtained in 120 consecutive cases involving patients presenting with drugresistant MTLE, who underwent tailored anteromesial temporal lobe resection, and correlated seizure outcome with pathological findings. They identified 5 histopathological groups: Group 1-ELGT, alone or associated with other lesions (30 cases); Group 2-isolated FCD (17 cases); Group 3-MTS, with or without GCP (28 cases); Group 4-MTS associated with FCD, with or without GCP (37 cases); Group 5-other lesions (8 cases).Results. Engel Class I outcome was observed in 83% of patients with ELGT (Class IA in 63%); in 59% of patients with isolated FCD, with FCD Type II showing a better prognosis than FCD Type I; in 82% of patients with isolated MTS (Class IA in 50%), with MTS Type 1a and MTS Type 1b showing a better prognosis than MTS Type 2 and patients with MTS and GCP having better postsurgical results than those with MTS without GCP. Engel Class I outcome was also achieved in 84% of patients with FCD associated with MTS (Engel Class IA in 62%); also in this group MTS 1a and MTS 1b associated with FCD showed a better prognosis than FCD associated with MTS 2. Finally, Engel Class I was also achieved in 2 patients with vascular malformation and in 1 with a temporal pole encephalocele.Conclusions. Patients with MTLE and ELGT, MTS, or MTS associated with FCD showed the best postsurgical seizure outcome (Engel Class I in more than 80% of cases), whereas only 63% of patients with isolated FCD achieved the same type of outcome. Interestingly, the analysis of seizure outcome in histopathological subtypes of FCD and of MTS showed different prognoses in the different pathological subgroups, with worse outcomes for atypical MTS, absence of GCP, and isolated FCD Type I. 37Abbreviations used in this paper: EEG = electroencephalographic; ELGT = epilepsy-associated low-grade tumor; FCD = focal cortical dysplasia; GCP = granule cell ...

Short‐ and long‐term surgical outcomes of temporal lobe epilepsy associated with hippocampal sclerosis: Relationships with neuropathology

“…26 (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) 36 (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41) 85 (91) 62 (67) Type 1 70 (74) 33 (47) 38 (54) 27 (39) 13 (19) 6 (3-10) (25) 7 (30) 11 (48) 5 (22) 7 ( 42 (43) 58 (60) 22 (23) 19 (20) 8 (4-13)…”

“…[18][19][20][21] Furthermore, very few reports have considered outcomes in relation to the different HS types, and then only in the short term. 12,14,15,[22][23][24][25] The aim of this study was to investigate the relationships between the different ILAE HS types, their etiologic factors, and short-and long-term postsurgical seizure outcomes in a large cohort of HS patients undergoing surgery for drugresistant TLE because a greater understanding of the factors predicting surgical outcomes, including histopathology, may improve the selection of surgical candidates and their postsurgical clinical management.…”

Hippocampal subfield segmentation in temporal lobe epilepsy: Relation to outcomes

“…Postoperative outcome has been shown to be superior in patients with TLE who, after resection, were retrospectively shown to have classical patterns of HS (ie, preservation of CA2 neurons) or total HS (ie, neuronal loss throughout the CA), whereas patients with circumscribed neuronal loss of CA1 or CA4 tend to have poorer outcomes 17, 18, 19, 20. Mathern et al (1996) had previously reported that patients with initial precipitating injuries were more likely to benefit from surgery and had neuronal cell loss in CA1 and presubiculum regions.…”

“…Importantly, these patterns of HS appear to be related to various clinical aspects of TLE and may have significance for postoperative prognosis. ILAE HS type 1 is more frequently associated with a history of initial precipitating injuries in early childhood, an early seizure onset and improved seizure outcome after temporal lobe surgery 17, 18, 19, 20. ILAE HS type 2 and 3 appear to be associated with a later age of onset and a less favorable postoperative outcome,17, 18, 19, 20 although there are some inconsistencies in these relationships 21.…”

“…ILAE HS type 1 is more frequently associated with a history of initial precipitating injuries in early childhood, an early seizure onset and improved seizure outcome after temporal lobe surgery 17, 18, 19, 20. ILAE HS type 2 and 3 appear to be associated with a later age of onset and a less favorable postoperative outcome,17, 18, 19, 20 although there are some inconsistencies in these relationships 21. Given the clinical relevance of regional hippocampal subfield pathology in TLE, it is important to develop and apply MRI approaches that permit assessment of hippocampal subfield structure and volume in this patient group, particularly if such non‐invasive imaging measures can be used to predict treatment outcome.…”