title: Hippocampal malformations do not necessarily evolve into hippocampal sclerosis.
abstract: OBJECTIVE
  Hippocampal malformations have been proposed to underlie or evolve into hippocampal sclerosis, a common cause of refractory partial epilepsy. We report two patients with chronic epilepsy and developmental abnormalities of the hippocampus and cortex. We seek to address, in patients with recurrent convulsive seizures over many decades, whether hippocampal malformations necessarily progress to hippocampal sclerosis.
  
  
  METHODS
  The first patient died at age 76 years and had experienced convulsive seizures for 43 years. The second patient, aged 64 years at death, had experienced convulsive seizures for 49 years. The brains were processed routinely. Immunohistochemistry for dynorphin and neuropeptide Y was performed.
  
  
  RESULTS
  The first case exhibited bilateral perisylvian polymicrogyria. Both hippocampi demonstrated abnormal convolution in the CA1 subfield and subiculum. In the second case, periventricular heterotopia was found in the wall of the right lateral ventricle. The right hippocampus was abnormally oriented with excessive convolutions of the pyramidal cell layer between CA1 and the subiculum. In neither patient did the hippocampi exhibit neuronal loss. Furthermore, dynorphin immunohistochemistry revealed no reactivity in the molecular layers, and staining with neuropeptide Y confirmed normal numbers of hilar interneurons.
  
  
  CONCLUSIONS
  These two cases demonstrate histologically that, even in long-standing epilepsy, malformations of the hippocampus do not necessarily develop into hippocampal sclerosis.
authors.affiliation: Department of Clinical and Experimental Epilepsy, The Institute of Neurology, University College London, London, England.
authors.forename: Arjune
authors.initials: A
authors.lastname: Sen
authors.forename: Maria
authors.initials: M
authors.lastname: Thom
authors.forename: Lillian
authors.initials: L
authors.lastname: Martinian
authors.forename: Stephen
authors.initials: S
authors.lastname: Dawodu
authors.forename: Sanjay M
authors.initials: SM
authors.lastname: Sisodiya
mesh_terms: D000368:Aged; D001921:Brain / Q000473:pathology; D002908:Chronic Disease; D004827:Epilepsy / Q000175:diagnosis / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006624:Hippocampus / Q000002:abnormalities* / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012598:Sclerosis