(PO-078) (PO-078) An older man with anti-NMDA receptor encephalitis: Case report and review of literature

Background: Anti-NMDA receptor encephalitis is characterized by rapid progression of psychiatric and cognitive symptoms secondary to autoimmune destruction of the GluN1 subunit of NMDA receptors and is most common in young female patients subsequently diagnosed with ovarian teratomas (Gurrera, 2019). With prevalent psychiatric symptoms, many patients initially present to psychiatry, leading to misdiagnosis and delay in treatment (Marinova, 2019). We report the case of a 76-year-old male who presented with acute deterioration of mental status, catatonia, and psychosis who was diagnosed with anti-NMDA receptor encephalitis.

Case: The patient is a 76-year-old man with past medical history of prostate cancer and no past psychiatric history, who presented with altered mental status including catatonic symptoms. He had presented to two other hospitals 2-3 weeks earlier with related symptoms, was diagnosed with dementia and myasthenia gravis and discharged to a rehab facility without further workup. During rehab, he reported headaches and dizziness to a friend. Prior to the onset of his illness, he was an active, intellectual, high functioning adult with no history of dementia or confusion. His acute decline led to a wide differential and psychiatry was consulted. There were no abnormal findings on MRI and vEEG indicated encephalopathy. Lumbar puncture results were positive for anti-NMDA receptor antibodies. The patient was treated with IVIG and steroids, after which the patient's symptoms significantly improved.




Discussion: We describe a unique case, as literature shows that anti-NMDA receptor encephalitis affects females four times as frequently as males and only about 5% of those affected are above 45 years old (Irvine, 2020). This patient presented with very few classic signs of encephalitis such as seizures, photophobia, neck pain/stiffness, but did have headaches, and on chart review, his presentation was not atypical for anti-NMDA receptor encephalitis. It is possible that the fact that the patient was an older male led to a delay in diagnosis, as he had presented to two hospitals previously without work up for encephalitis.




Conclusion: Inclusion of autoimmune encephalitides in the differential of such patients should be considered to avoid delay in diagnosis and treatment and thus further progression of disease. Potential retrospective study on the time frame of inclusion of disease within differentials and initiation of treatment could be clinically beneficial for improving prognosis.



References

Gurrera RJ. Frequency and temporal sequence of clinical features in adults with anti-NMDA receptor encephalitis presenting with psychiatric symptoms. Psychol Med. 2019 Dec;49(16):2709-2716



Marinova Z, Bausch-Becker N, Savaskan E. Anti-N-methyl-d-aspartate receptor encephalitis in an older patient presenting with a rapid onset of delusions and amnesia. BMJ Case Rep. 2019 Apr 15;12(4):e228512.



Irvine E, Cheng D, Xiao D. Atypical presentation of anti-N-methyl-D-aspartate receptor encephalitis in a 61-year-old Hispanic man. BMJ Case Rep. 2020 Dec 10;13(12):e238347

Learning Objectives:

• Participants will learn the importance of including anti-NMDA encephalitis in differential diagnoses when encountering patients with acute onset of psychiatric symptoms.