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Updated: Feb 14, 2026

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Histopathology of 3 Tesla MRI-negative extratemporal focal epilepsies

Evangelos Kogias1, Dirk-Matthias Altenmüller2, Jan-Helge Klingler1

  • 1Department of Neurosurgery, Medical Center-University of Freiburg, Germany.

Journal of Clinical Neuroscience : Official Journal of the Neurosurgical Society of Australasia
|February 10, 2018
PubMed
Abstract

Insights

Histopathology in 3 Tesla MRI-negative extratemporal epilepsies reveals a lower incidence of focal cortical dysplasia (FCD) using current ILAE criteria. Re-evaluation may identify mild malformations of cortical development (mMCD) type II in cases previously diagnosed as gliosis.

Area of Science:

  • Neurology
  • Pathology
  • Neurosurgery

Background:

  • Limited histopathological data exists for 3 Tesla MRI-negative extratemporal epilepsies.
  • Previous studies often used older classification criteria (Palmini) and included lower-field MRI.
  • Common findings in older series included focal cortical dysplasia (FCD), gliosis, or normal histology.

Purpose of the Study:

  • To analyze the histopathology of 3 Tesla MRI-negative extratemporal epilepsies using current International League Against Epilepsy (ILAE) criteria.
  • To investigate the potential correlation between histopathological findings and 1-year postoperative seizure outcome.
  • To compare diagnostic yield between older Palmini criteria and current ILAE criteria.

Main Methods:

  • Histopathological examination of 16 epilepsy substrates from 3 Tesla MRI-negative cases.
  • Initial prospective analysis using standard stains, immunohistochemistry, and Palmini criteria.
  • Retrospective re-evaluation using phospho-6 and calretinin stains, and ILAE criteria.

Main Results:

  • Initial review (Palmini criteria) identified 75% FCD (5 FCD Palmini 1b, 2 1a, 5 2a) and 4 cases of gliosis.
  • Revised review (ILAE criteria) identified 56% FCD (6 FCD type IIa, 2 FCD Ib) and 7 mild malformations of cortical development (mMCD) type II.
  • No cases were classified as isolated gliosis after the ILAE criteria review.

Conclusions:

  • The incidence of FCD in 3 Tesla MRI-negative extratemporal epilepsies may be lower than previously reported.
  • Current ILAE criteria improve diagnostic accuracy, potentially identifying mMCD type II in cases previously deemed gliosis or normal.
  • Accurate histopathological classification is crucial for understanding epilepsy substrates and outcomes.
Keywords:
Epilepsy surgeryFocal cortical dysplasiaHistopathologyMRI-negative

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