title: Focal cortical dysplasias in temporal lobe epilepsy surgery: Challenge in defining unusual variants according to the last ILAE classification.
abstract: OBJECTIVE
  Focal cortical dysplasias (FCDs) represent a common architectural cortical disorder underlying pharmacoresistant focal epilepsy. The recent ILAE classification defines different types of FCDs based on their histopathological features, MRI imaging, and presumed pathogenesis; however, their clinical features and their prognostic significance are still incompletely defined. In addition, the combination of different histopathological abnormalities can represent "unusual" subtypes that can be difficult to classify. The aim of our study was to analyze the incidence and the significance of these "unusual" subtypes of FCDs in drug-resistant mesial temporal lobe epilepsy (MTLE).
  
  
  METHODS
  We retrospectively analyzed 133 patients consecutively submitted to tailored anteromesial temporal lobe resection for pharmacoresistant MTLE. Seizure onset, seizure duration, age at surgery, and postoperative seizure outcome were evaluated in relation to the different neuropathological groups defined according to the new ILAE classification.
  
  
  RESULTS
  Focal cortical dysplasias were found in 80 out of 133 patients. Six patients were affected by isolated FCD type I, 12 patients by FCD type II, and 44 patients by FCD type III. Furthermore, we found 18 "atypical" cases (20.5% of all FCD cases and 26.6% of FCDs associated with a principal lesion): 10 cases of associated FCD type II-hippocampal sclerosis (HS) and 8 cases associated with FCD II-epilepsy-associated tumors (EATs).
  
  
  CONCLUSIONS
  Our results indicate that "unusual" subtypes of FCDs, in particular associated FCD type II, are not uncommon findings, suggesting that they deserve a classification recognition. Similarities in seizure outcome and immunohistochemical and molecular evidences, shared by FCD type II+EATs and EATs, suggest a common pathogenic link. The choice to create a specific unifying class or, on the contrary, to also include "associated FCD type II" in the definition of the new unifying class FCD type III should be further discussed.
authors: IRCCS Institute of Neurological Science of Bologna, Division of Neurosurgery, Bellaria Hospital, Bologna, Italy. Electronic address: matteo.martinoni@gmail.com.
authors: Matteo
authors: M
authors: Martinoni
authors: Department of Biomedical and NeuroMotor Sciences (DiBiNeM), Section of Pathology "M.Malpighi", Bellaria Hospital, University of Bologna, Bologna, Italy.
authors: Gianluca
authors: G
authors: Marucci
authors: IRCCS Institute of Neurological Sciences of Bologna, Division of Neurology, Bellaria Hospital, Bologna, Italy; Danish Epilepsy Centre, Dianalund, Denmark.
authors: Guido
authors: G
authors: Rubboli
authors: IRCCS Institute of Neurological Sciences of Bologna, Division of Neurology, Bellaria Hospital, Bologna, Italy.
authors: Lilia
authors: L
authors: Volpi
authors: IRCCS Institute of Neurological Sciences of Bologna, Division of Neurology, Bellaria Hospital, Bologna, Italy.
authors: Patrizia
authors: P
authors: Riguzzi
authors: IRCCS Institute of Neurological Sciences of Bologna, Section of Neuroradiology, Bellaria Hospital, Bologna, Italy.
authors: Federica
authors: F
authors: Marliani
authors: IRCCS Institute of Neurological Sciences of Bologna, Section of Neuroradiology, Bellaria Hospital, Bologna, Italy.
authors: Francesco
authors: F
authors: Toni
authors: Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
authors: Ilaria
authors: I
authors: Naldi
authors: IRCCS Institute of Neurological Sciences of Bologna, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
authors: Francesca
authors: F
authors: Bisulli
authors: IRCCS Institute of Neurological Sciences of Bologna, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
authors: Paolo
authors: P
authors: Tinuper
authors: IRCCS Institute of Neurological Sciences of Bologna, Division of Neurology, Bellaria Hospital, Bologna, Italy.
authors: Roberto
authors: R
authors: Michelucci
authors: IRCCS Institute of Neurological Sciences of Bologna, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
authors: Agostino
authors: A
authors: Baruzzi
authors: IRCCS Institute of Neurological Science of Bologna, Division of Neurosurgery, Bellaria Hospital, Bologna, Italy.
authors: Marco
authors: M
authors: Giulioni
mesh_terms: D000293:Adolescent; D000328:Adult; D004833:Epilepsy, Temporal Lobe / Q000145:classification* / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D006801:Humans; D038622:Internationality; D008297:Male; D054220:Malformations of Cortical Development / Q000145:classification* / Q000175:diagnosis / Q000601:surgery*; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
keywords: Double pathology; Dual pathology; Focal cortical dysplasia; Glioneuronal tumors; Hippocampal sclerosis; Temporal lobe epilepsy