Autoimmune limbic encephalitis

Case contributed by Stephen Stuckey
Diagnosis probable


Progressive confusion.

Patient Data

Age: 40 years
Gender: Female

Both mesial temporal lobes and hippocampal tails demonstrate high T2 signal, best seen on FLAIR.


Nuclear medicine

PET demonstrates increase uptake in the limbic system. 

Case Discussion

Limbic encephalitis may be infectious (typically HSV) or autoimmune, including paraneoplastic and non-paraneoplastic causes. 

Signal change may occur in the following locations:

On imaging, autoimmune limbic encephalitis generally affects the amygdala and hippocampus, whilst infectious limbic encephalitis typically involves multiple sites. 

Patchy contrast enhancement and diffusion restriction are common.

Hemorrhage suggests HSV.

In HSV, DWI changes may precede T2 signal change.

There are an increasing number of recognized tumors associated with paraneoplastic limbic encephalitis, including lung (classically small cell), ovarian, breast, germ cell tumors and thymic tumors.

Similarly, there are an increasing number of autoantibodies now recognized in non-paraneoplastic limbic encephalitis. In this case, the antibody isolated was anti-GAD.

There is a considerable overlap of antibodies in paraneoplastic and non-paraneoplastic encephalitis.

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