IMPORTANT: We currently have a number of bugs related to image cropping and are actively trying to resolve them. In the meantime, we have disabled cropping. Apologies for any inconvenience. Stay informed: radiopaedia.org/chat

Autoimmune limbic encephalitis

Case contributed by Stephen Stuckey
Diagnosis probable

Presentation

Progressive confusion.

Patient Data

Age: 40 years
Gender: Female

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

PET

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.

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.