title: Extent of mossy fiber sprouting in patients with mesiotemporal lobe epilepsy correlates with neuronal cell loss and granule cell dispersion.
abstract: The most frequent finding in temporal lobe epilepsy is hippocampal sclerosis, characterized by selective cell loss of hippocampal subregions CA1 and CA4 as well as mossy fiber sprouting (MFS) towards the supragranular region and granule cell dispersion. Although selective cell loss is well described, its impact on mossy fiber sprouting and granule cell dispersion remains unclear.
  
  
  
  In a single center series, we examined 319 human hippocampal specimens, collected in a 15-years period. Hippocampal specimens were stained for neuronal loss, granule cell dispersion (Wyler scale I-IV, Neu-N, HE) and mossy fiber sprouting (synaptoporin-immunohistochemistry). For seizure outcome Engel score I-IV was applied.
  
  
  
  In Wyler I and II specimens, mossy fibers were found along their natural projection exclusively in CA4 and CA3. In Wyler III and IV, sprouting of mossy fibers into the molecular layer and a decrease of mossy fibers in CA4 and CA3 was detected. Mean granule cell dispersion was extended from 121μm to 185μm and correlated with Wyler III-IV as well as mossy fiber sprouting into the molecular layer. Wyler grade, mossy fiber sprouting and granule cell dispersion correlated with longer epilepsy duration, late surgery and higher preoperative seizure frequency. Parameters analyzed above did not correlate with postoperative seizure outcome.
  
  
  
  Mossy fiber sprouting might be a compensatory phenomenon of cell death of the target neurons in CA4 and CA3 in Wyler III-IV. Axonal reorganization of granule cells is accompanied by their migration and is correlated with the severity of cell loss and epilepsy duration.
authors.affiliation: Department of Neurosurgery, University Medical Center, Albert-Ludwigs-University, Breisacher Strasse 64, 79106 Freiburg im Breisgau, Germany. Electronic address: barbara.schmeiser@uniklinik-freiburg.de.
authors.forename: Barbara
authors.initials: B
authors.lastname: Schmeiser
authors.affiliation: Department of Neurosurgery, University Medical Center, Albert-Ludwigs-University, Breisacher Strasse 64, 79106 Freiburg im Breisgau, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Zentner
authors.affiliation: Institute of Neuropathology, University Medical Center, Center for Biological Signaling Studies (BIOSS), Albert-Ludwigs-University, Breisacher Strasse 64, 79106 Freiburg im Breisgau, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Prinz
authors.affiliation: Epilepsy Center, University Medical Center, Albert-Ludwigs-University, Breisacher Strasse 64, 79106 Freiburg im Breisgau, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Brandt
authors.affiliation: Department of Neurosurgery, University Medical Center, Goethe-University, Schleusenweg 2-16, Frankfurt am Main, Germany.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Freiman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D056654:CA3 Region, Hippocampal / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D016923:Cell Death; D002465:Cell Movement; D002648:Child; D002675:Child, Preschool; D000069279:Drug Resistant Epilepsy / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D004833:Epilepsy, Temporal Lobe / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D019599:Mossy Fibers, Hippocampal / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D009474:Neurons / Q000473:pathology* / Q000502:physiology; D055815:Young Adult
keywords: Granule cell dispersion; Mossy fiber sprouting; Mossy fibers; Seizure outcome; Wyler grade