Helena Ariño1, Ester Coutinho2, Thomas A Pollak3, Robert Stewart3. 1. Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK. Electronic address: helena.arino_rodriguez@kcl.ac.uk. 2. King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK. 3. King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK; South London and Maudsley NHS Foundation Trust, London, UK.
Abstract
OBJECTIVE: To evaluate the frequency of anti-NMDAR encephalitis in a secondary mental health service and investigate the challenges of its diagnosis in routine clinical practice. METHODS: Patients whose electronic health records registered an indication for NMDAR-IgG assessment were selected and seropositive patients were reviewed. RESULTS: In 1661 patients assessed for NMDAR-IgG over 12 years, the positivity rate was 3.79% (95% confidence interval [CI]: 2.87-4.70%). The working diagnosis at assessment was new onset psychosis in 38.7% and a chronic psychotic syndrome in 34.0%. Among seropositive patients, 30 (47.6%, 95%CI: 35.8-59.7%) had a final alternative diagnosis different from encephalitis after a median period of 49 months from onset. Patients with a final diagnosis of encephalitis were more frequently female (27/35 vs 13/30, p = 0.011) than other seropositive patients and had more frequently an acute (34/35 vs 11/30, p < 0.001), fluctuating (21/23 vs 4/27, p < 0.001) or agitated (32/32 vs 10/26, p < 0.001) presentation. Nine encephalitic patients received specialized follow-up for chronic neuropsychiatric problems including learning disabilities, organic personality disorder, anxiety, fatigue, obsessive-compulsive and autism-like disorder. CONCLUSIONS: In a psychiatric setting, NMDAR-IgG seropositivity rates were low with a positive predictive value for encephalitis around 50% when screened patients had chronic presentations and absence of other diagnostic criteria for encephalitis or psychosis of autoimmune origin. Chronic neuropsychiatric problems in anti-NMDAR encephalitis are not uncommon, so better diagnostic and treatment strategies are still needed.
OBJECTIVE: To evaluate the frequency of anti-NMDAR encephalitis in a secondary mental health service and investigate the challenges of its diagnosis in routine clinical practice. METHODS: Patients whose electronic health records registered an indication for NMDAR-IgG assessment were selected and seropositive patients were reviewed. RESULTS: In 1661 patients assessed for NMDAR-IgG over 12 years, the positivity rate was 3.79% (95% confidence interval [CI]: 2.87-4.70%). The working diagnosis at assessment was new onset psychosis in 38.7% and a chronic psychotic syndrome in 34.0%. Among seropositive patients, 30 (47.6%, 95%CI: 35.8-59.7%) had a final alternative diagnosis different from encephalitis after a median period of 49 months from onset. Patients with a final diagnosis of encephalitis were more frequently female (27/35 vs 13/30, p = 0.011) than other seropositive patients and had more frequently an acute (34/35 vs 11/30, p < 0.001), fluctuating (21/23 vs 4/27, p < 0.001) or agitated (32/32 vs 10/26, p < 0.001) presentation. Nine encephalitic patients received specialized follow-up for chronic neuropsychiatric problems including learning disabilities, organic personality disorder, anxiety, fatigue, obsessive-compulsive and autism-like disorder. CONCLUSIONS: In a psychiatric setting, NMDAR-IgG seropositivity rates were low with a positive predictive value for encephalitis around 50% when screened patients had chronic presentations and absence of other diagnostic criteria for encephalitis or psychosis of autoimmune origin. Chronic neuropsychiatric problems in anti-NMDAR encephalitis are not uncommon, so better diagnostic and treatment strategies are still needed.