Reversible signal abnormalities in the hippocampus and neocortex after prolonged seizures

Stephen Chan*, Steven S.M. Chin, Krishnan Kartha, Douglas R. Nordli, Robert R. Goodman, Timothy A. Pedley, Sadek K. Hilal

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


PURPOSE: To investigate the phenomenon of reversible increased signal intensity of medial temporal lobe structures and cerebral neocortex seen on MR images of six patients with recent prolonged seizure activity. METHODS: After excluding patients with known causes of reversible signal abnormalities (such as hypertensive encephalopathy), we retrospectively reviewed the clinical findings and MR studies of six patients whose MR studies showed reversible signal abnormalities. MR pulse sequences included T2-weighted spin-echo coronal views or conventional short-tau inversion-recovery coronal images of the temporal lobes. RESULTS: All six MR studies showed increased signal intensity within the medial temporal lobe, including the hippocampus in five studies. All follow up MR examinations showed partial or complete resolution of the hyperintensity within the medial temporal lobe and the neocortex. In one patient, results of a brain biopsy revealed severe cerebral cortical gliosis. Temporal lobectomy performed 4 years later showed moderate cortical gliosis and nonspecific hippocampal cell loss and gliosis. CONCLUSION: Significant hyperintensity within the temporal lobe is demonstrable on MR images after prolonged seizure activity, suggestive of seizure-induced edema or gliosis. Damage to medial temporal lobe structures by prolonged seizure activity indicates a possible mechanism of epileptogenic disorders.

Original languageEnglish (US)
Pages (from-to)1725-1731
Number of pages7
JournalAmerican Journal of Neuroradiology
Issue number9
StatePublished - Oct 1 1996


  • Brain, magnetic resonance
  • Brain, temporal lobe
  • Hippocampus
  • Seizures

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Clinical Neurology


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