Atypical Psychiatric Presentations of Autoimmune Encephalitis: A Case Series and Proposed Clinical Approach to Diagnosis

Abstract

Background: knowledge and detection of seronegative autoimmune encephalitis (AE) is growing rapidly, but typical psychiatric presentations risk misdiagnosis or delay in diagnosis with worse prognostic outcomes. Paraclinical markers are useful when positive, and integral to the current diagnostic framework yet have limited sensitivities leaving an unknown percentage of patients without diagnosis or treatment. Cases not meeting diagnostic criteria pose a particular clinical challenge regarding diagnosis and treatment decision making and highlight the need for further understanding of AE as well as the role of autoimmunity in psychiatric illness itself. Methods: Informed consent was obtained from five patients, three females and two males, in accordance with the University of Alberta medical ethics guidelines and regulations. Literature was reviewed for clinical features correlating with AE and compared to primary psychiatric illnesses of bipolar and schizophrenia. Results: Five cases of atypical, suspected AE not meeting diagnostic criteria are described with primarily psychiatric symptoms and minimal paraclinical features yet responded to immune therapy. Conclusions: Diagnostic challenges occur when patients present with features suspicious of autoimmune etiology yet do not meet criteria based on minimal paraclinical supportive findings. To what degree these false negatives exist more broadly is unknown yet raises further questions around consideration of immune treatment vs standard psychiatric care, especially if a subset can have a better prognostic outcome where they offered such treatments. Speculation occurs in the literature around whether these represent a false negative or undetected AE, a discrete entity such as autoimmune psychosis, or inflammatory mediated psychiatric illness.