PGY3 Andrea Cedeno presented a case of a young male with no significant PMH who came in with a few weeks of headache, confusion and change in behavior. After an extensive work-up he was found to have anti-NMDA receptor encephalitis.
When evaluating for this disorder, infectious causes (patient had an LP which showed a very mild lymphocytic pleocytosis) and rheumatologic causes (ANA, ANCA, RF, ACE all negative/normal) should be ruled out. To rule out other organic causes, our patient had imaging which showed no evidence of vascular malformations, leptomeningeal enhancement, or demyelinating lesions.
The diagnosis of anti-NMDA receptor encephalitis is confirmed by the detection of IgG antibodies to the NMDA receptor subunit (GluN1) in the CSF. Lymphocytic pleocytosis or oligoclonal bands can be present and support the diagnosis. While CSF IgG Abs are both sensitive and specific for this disease, serum Abs, IgM, and IgA Abs against the NMDA receptor are non-specific and have no role in this disease.
Remember, anti-NMDA receptor encephalitis is associated with underlying malignancy. Most commonly it is associated with ovarian teratomas, but can also be associated with SCLC, NETs, testicular tumors, and Hodgkin lymphoma. Underlying malignancy is more common in females (up to 30%) compared to males (< 5%). A full physical exam and imaging should be completed to search for age-appropriate malignancy when anti-NMDA receptor encephalitis is the presenting symptom.
Thanks for going over such a great case, Andrea!