title: Small temporal pole encephalocele: A hidden cause of "normal" MRI temporal lobe epilepsy.
abstract: OBJECTIVE
  Small temporal pole encephalocele (STPE) can be the pathologic substrate of epilepsy in a subgroup of patients with noninformative magnetic resonance imaging (MRI). Herein, we analyzed the clinical, neurophysiologic, and radiologic features of the epilepsy found in 22 patients with STPE, and the frequency of STPE in patients with refractory focal epilepsy (RFE).
  
  
  METHODS
  We performed an observational study of all patients with STPE identified at our epilepsy unit from January 2007 to December 2014. Cases were detected through a systematic search of our database of RFE patients evaluated for surgery, and a prospective collection of patients identified at the outpatient clinic. The RFE database was also employed to analyze the frequency of STPE among the different clinical subgroups.
  
  
  RESULTS
  We identified 22 patients with STPE (11 women), including 12 (4.0%) of 303 patients from the RFE database, and 10 from the outpatient clinic. The median age was 51.5 years (range 29-75) and the median age at seizure onset was 38.5 years (range 15-73). Typically, 12 (80%) of 15 patients with left STPE reported seizures with impairment of language. Among the RFE cases, STPE were found in 9.6% of patients with temporal lobe epilepsy (TLE), and in 0.5% of those with extra-TLE (p = 0.0001). STPEs were more frequent in TLE patients with an initial MRI study reported as normal (23.3%) than in those with MRI-visible lesions (1.4%; p = 0.0002). Stereo-electroencephalography was performed in four patients, confirming the localization of the epileptogenic zone at the temporal pole with late participation of the hippocampus. Long-term seizure control was achieved in four of five operated patients.
  
  
  CONCLUSIONS
  STPE can be a hidden cause of TLE in a subgroup of patients with an initial report of "normal" MRI. Early identification of this lesion may help to select patients for presurgical evaluation and tailored resection.
authors.affiliation: Epilepsy Unit, Department of Neurology, Hospital Ruber Internacional, Madrid, Spain.|Epilepsy Unit, Department of Neurology, Hospital Ramon y Cajal, Madrid, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Toledano
authors.affiliation: Department of Neurology, Hospital Ruber Internacional, Madrid, Spain.
authors.forename: Adolfo
authors.initials: A
authors.lastname: Jiménez-Huete
authors.affiliation: Department of Basic Psychology, Autonoma University of Madrid, Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Campo
authors.affiliation: Department of Biological and Health Psychology, Autonoma University of Madrid, Madrid, Spain.
authors.forename: Claudia
authors.initials: C
authors.lastname: Poch
authors.affiliation: Epilepsy Unit, Department of Neurology, Hospital Ruber Internacional, Madrid, Spain.|Epilepsy Unit, Department of Neurology, Hospital Clinico San Carlos, Madrid, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: García-Morales
authors.affiliation: Department of Neurosurgery, Hospital Ruber Internacional, Madrid, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Gómez Angulo
authors.affiliation: Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Coras
authors.affiliation: Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany.
authors.forename: Ingmar
authors.initials: I
authors.lastname: Blümcke
authors.affiliation: Department of Neuroradiology, Hospital Ruber Internacional, Madrid, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Álvarez-Linera
authors.affiliation: Epilepsy Unit, Department of Neurology, Hospital Ruber Internacional, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Gil-Nagel
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging*; D016208:Databases, Factual / Q000706:statistics & numerical data; D004569:Electroencephalography; D004677:Encephalocele / Q000150:complications*; D004833:Epilepsy, Temporal Lobe / Q000000981:diagnostic imaging* / Q000209:etiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008588:Meningocele / Q000150:complications*; D008875:Middle Aged; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D014741:Video Recording
keywords: Aphasia; Encephalocele; Epilepsy semiology; Epilepsy surgery; Temporal lobe epilepsy