Thursday, February 18, 2010

Limbic Encephalitis

Limbic encephalitis, also known as paraneoplastic encephalitis, refers to the subacute (weeks) development of severe memory loss and behavioral abnormalities, and may be accompanied mood alteration, delusions, and seizures.

Limbic encephalitis is almost always associated with an underlying malignancy, most commonly small cell carcinoma of the lung, but association with autoimmune disorders such as lupus has also been reported.

Imaging findings predominate in one or both temporal lobes. CT may show low attenuation areas in the temporal lobes. In the acute phase, MRI may show T2/FLAIR hyperintensity in the temporal lobes, while FDG/PET may show increased uptake. Contrast-enhanced MRI may show Patchy enhancement. Decreased FDG uptake may be seen in the chronic phase.

Differential considerations for the imaging appearance include:
  • Herpes simplex encephalitis
  • Vasculitis
  • Low-grade astrocytoma (unilateral)
  • Status epilepticus
  • Gliomatosis cerebri
  • Metastases
  • Radiation therapy


  • Kano O, Arasaki K, Ikeda K, Aoyagi J, Shiraishi H, Motomura M, Iwasaki Y. Limbic encephalitis associated with systemic lupus erythematosus. Lupus. 2009 Dec;18(14):1316-9.
  • Ravin CE, Bergin D, Bisset GS 3rd, Fine SA, Guo AC, Helms CA, Hollingsworth CL, Kirk SR, Ravenel JG. Image interpretation session: 2000. Radiographics. 2001 Jan-Feb;21(1):267-87.


  1. Hi looks intresting as they state nearly always mediated by an underlying malignancy. I am however hearing of more instances termed (NPLE) None paraneoplastic Limbic Encephalitis instances. I guess if no malignancy is found many may fall into this title. Have you any experence of Anti-NMDA receptor encephalitis?

  2. Thanks for the comment and for introducing me to anti-NNMDA-receptor encephalitis. I don't know much about this condition. On cursory review it seems like it's similar to the classic limbic encephalitis in that the hypothesized mechanism is one of antibodies to antigens found on neurons. Also, it seems that MRI findings are similar in these two conditions. I would consult with a neurologist who is familiar with this rather uncommon condition.


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