Abstract Details

Title Alternative Diagnoses in Patients Referred to Neuroimmunology for Autoimmune Encephalitis Evaluation

Topic Autoimmune Neurology

Presentation(s) P5 - Poster Session 5 (8:00 AM-9:00 AM)

Poster/Presentation
Number 8-006

Objective To evaluate alternative diagnoses in patients referred to neuroimmunology for evaluation of autoimmune encephalitis and/or positive neuronal antibodies.

Background With the increased awareness of autoimmune encephalitis, there has been an increase in misdiagnosis of this condition. This usually results from misinterpretation of clinically irrelevant neural antibodies or improper suspicion of antibody-negative autoimmune encephalitis.

Design/Methods We retrospectively evaluated all cases referred to our center for evaluation of autoimmune encephalitis and/or a positive neural antibody. We calculated the frequency and characteristics of patients who were eventually diagnosed with an alternative diagnosis.

Results The dataset included 125 patients referred in the period from 2017 to 2024. Of the total, 70 patients (56%) were referred for a positive neural antibody and 55 patients (44%) were referred for evaluation of a possible antibody-negative autoimmune encephalitis. An alternative diagnosis was found in 40 patients (32%) including 21 patients (52% of the total patients with an alternative diagnosis) with clinically-irrelevant neural antibodies, and 19 patients (48%) who were referred for evaluation of antibody-negative disease. The most common clinically irrelevant antibodies included one or more of the following antibodies: GAD65 (10 including 2 with high titer), VGCC (4), VGKC (3), AchG (2), GABA-BR (2), NMDAR (1), LGI1 (1), and GFAP (1). The most common alternative diagnoses in the whole cohort included somatic symptom disorder (30%), primary psychiatric disorder (schizophrenia or bipolar- 17.5%), other immune-mediated disorders (15%), metabolic encephalopathy/myoclonus (7.5%), genetic disorders (7.5%), neurodegenerative disorders (7.5%), and miscellaneous causes(12.5%).

Conclusions Alternative diagnoses are common in patients referred for autoimmune encephalitis evaluation and include mostly psychiatric, metabolic, neurodegenerative, or other autoimmune conditions. Alternative diagnoses are not restricted to patients with low clinical relevance neural antibodies as they are also seen in patients with antibodies of high clinical relevance and in antibody-negative patients.

Authors/Disclosures
Hesham A. Abboud, MD (University Hospitals Cleveland Medical Center) PRESENTER	Dr. Abboud has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Biogen. The institution of Dr. Abboud has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genentech . Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Alexion. Dr. Abboud has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Horizon. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving as a Consultant for BMS. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Alpine Pharma. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Horizon. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Cycle Pharma. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Axonics. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Biogen. Dr. Abboud has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Genentech. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for BMS. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Horizon. Dr. Abboud has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for TG Therapeutics. The institution of Dr. Abboud has received research support from Genentech . The institution of Dr. Abboud has received research support from Novartis. The institution of Dr. Abboud has received research support from BMS. The institution of Dr. Abboud has received research support from Sanofi-Genzyme. The institution of Dr. Abboud has received research support from The Guthy-Jackson Charitable Foundation. The institution of Dr. Abboud has received research support from UCB. Dr. Abboud has received publishing royalties from a publication relating to health care.
Sophia F. Damman	Ms. Damman has nothing to disclose.
Samhitha Rai	Miss Rai has nothing to disclose.
Aasef Shaikh, MD	Dr. Shaikh has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for Acorda.

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