T2/FLAIR Hyperintensity in Mesial Temporal Lobe: Challenging Differential Diagnosis

Curr Med Imaging. 2022;18(3):285-291. doi: 10.2174/1573405617666210712130555.


T2/FLAIR hyperintensity in the mesial temporal lobe is the most common MR finding of herpes simplex encephalitis, but may be observed in other infectious and non-infectious diseases. The former includes herpes human virus 6 encephalitis, Japanese encephalitis, and neurosyphilis, and the latter autoimmune encephalitis, gliomatosis cerebri, bilateral or paradoxical posterior cerebral artery infarction, status epilepticus, and hippocampal sclerosis. Thus, T2/FLAIR hyperintensity in the mesial temporal lobe is not a disease-specific magnetic resonance imaging finding, and these conditions must be differentiated to ensure proper treatment. We review diseases that present with T2/FLAIR hyperintensity in the mesial temporal lobe and provide a helpful flow chart based on clinical and radiologic features.

Keywords: Herpes simplex encephalitis; Japanese encephalitis; autoimmuneencephalitis; gliomatosis cerebri; herpes human virus 6 encephalitis; hippocampal sclerosis; ischemic stroke; neurosyphilis; status epilepticus.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Diagnosis, Differential
  • Encephalitis* / diagnosis
  • Encephalitis* / pathology
  • Hashimoto Disease* / diagnosis
  • Hashimoto Disease* / pathology
  • Humans
  • Magnetic Resonance Imaging / methods
  • Temporal Lobe / diagnostic imaging
  • Temporal Lobe / pathology