title: Nodular heterotopia: a neuropathological study of 24 patients undergoing surgery for drug-resistant epilepsy.
abstract: OBJECTIVE
  Despite the availability of detailed electroclinical and imaging data, only a few neuropathological studies of nodular heterotopia have been published. The aim of this study was to describe the neuropathological features of various types of nodular heterotopia obtained from patients undergoing surgery for intractable epilepsy.
  
  
  METHODS
  Specimens of heterotopic nodules taken from 24 patients were neuropathologically investigated using routine and immunocytochemical procedures, and the data were compared with magnetic resonance imaging (MRI), electroclinical findings, and surgical outcomes.
  
  
  RESULTS
  The neuropathological data distinguished two groups. Group 1 (14 patients, 78% in Engel class 1) had similar characteristics regardless of the size, number, or location of the nodules, with both projecting and local circuit neurons in the nodules intermingled with glial cells. Thirteen patients had focal cortical dysplasia. The nodules were identified by MRI in all cases. In group 2 (10 patients, 90% in Engel class 1), all of the nodules were within the temporal lobe and associated with hippocampal sclerosis or gangliogliomas. They were very small (undetected by MRI) and mainly formed by projecting neurons with no evidence of glial cells. All of the patients had cortical dysplasia.
  
  
  CONCLUSIONS
  The distinctive neuropathological features of the nodules in the two groups suggest different etiopathogenetic mechanisms. In group 2, the presence of nodular formations in association with cortical dysplasia and either hippocampal sclerosis or ganglioglioma raises a question concerning so-called dual pathology in the temporal lobe.
authors.affiliation: Division of Clinical Epileptology and Experimental Neurophysiology, IRCCS Foundation Neurological Institute C Besta, Milan, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Meroni
authors.forename: Carlo
authors.initials: C
authors.lastname: Galli
authors.forename: Manuela
authors.initials: M
authors.lastname: Bramerio
authors.forename: Laura
authors.initials: L
authors.lastname: Tassi
authors.forename: Nadia
authors.initials: N
authors.lastname: Colombo
authors.forename: Massimo
authors.initials: M
authors.lastname: Cossu
authors.forename: Giorgio
authors.initials: G
authors.lastname: Lo Russo
authors.forename: Rita
authors.initials: R
authors.lastname: Garbelli
authors.forename: Roberto
authors.initials: R
authors.lastname: Spreafico
mesh_terms: D000293:Adolescent; D001927:Brain Diseases / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D002828:Choristoma / Q000150:complications* / Q000378:metabolism / Q000473:pathology*; D004351:Drug Resistance; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery*; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000473:pathology; D009415:Nerve Net / Q000378:metabolism / Q000473:pathology; D013702:Temporal Lobe
chemical_list: D005904:Glial Fibrillary Acidic Protein