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Objective: Voltage-gated potassium channel antibodies are implicated in limbic encephalitis and currently included in first-episode psychosis organic screening guidelines. Individuals with high-positive voltage-gated potassium channel titres most commonly present with neurological symptoms as well as sleep, cognitive, behaviour, psychosis and mood disturbance. The significance of low-positive voltage-gated potassium channel antibody titres in psychiatric patients is unclear and has not been previously examined. We aim to describe a statewide cohort of psychiatric patients with low- and high-positive voltage-gated potassium channel titres and explore if this finding influenced clinical management and patient outcomes. Methods: A retrospective review of all voltage-gated potassium channel antibodies testing performed in public psychiatric services in Queensland, Australia, with comparison of the clinical presentation and long-term outcomes of low- and high-positive voltage-gated potassium channel titre cases. Specific antigen targets (leucine-rich glioma-inactivated protein 1 and contactin-associated protein 2 antibodies) were also assessed. Results: The overall prevalence of voltage-gated potassium channel antibody positivity in Queensland, public, psychiatric service testing was 0.3% (14/4098), with 12 cases of low-positive voltage-gated potassium channel titre, 2 cases of high-positive (leucine-rich glioma-inactivated protein 1 antibody positive) cases and a voltage-gated potassium channel negative contactin-associated protein 2 antibody positive case. No low-positive case developed neurological abnormalities or had abnormal paraclinical investigations. In comparison, both high-positive voltage-gated potassium channel/leucine-rich glioma-inactivated protein 1 cases and the contactin-associated protein 2 antibody positive case rapidly developed neurological symptoms, had abnormal paraclinical testing and improved only with immunotherapy. There was no later development of encephalitic symptoms in the low-positive cases over an average of 1067 days follow-up. Conclusion: Voltage-gated potassium channel antibody–associated limbic encephalitis was rare, and always associated with high antibody titres. Low-positive titres were not associated with the development of encephalitis over a long period of follow-up. The value of universal voltage-gated potassium channel antibody screening is unclear, and further prospective studies in first-episode psychosis populations are required. [ABSTRACT FROM AUTHOR]

Background: Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is an immune-mediated disorder which requires multi-disciplinary treatment including immunomodulation therapy. First presentation is most commonly to psychiatric services and continuing psychiatric care is required to treat disabling symptoms, such as behaviour disturbance, psychosis and catatonia. There is minimal available evidence to guide symptomatic treatment and concern for increased sensitivity to antipsychotics complicates traditional approaches. Methods: All cases of cerebrospinal fluid positive anti-NMDAR encephalitis tested in Queensland, Australia were identified. Demographic, clinical and therapeutic data were collected and reviewed by two independent clinicians. Pre-specified variables reflecting possible treatment side effects were compared. Results: The majority of the 30 cases (83%) had early psychiatric symptoms and were treated with antipsychotics (67%), average daily olanzapine equivalence dose of 11.5 mg, prior to immunomodulation therapy. Although there was an 88% reduction in cases with aggression, there was little improvement in psychosis, affective symptoms or catatonia with antipsychotics alone. In the cases with psychiatric symptoms, there was no significant difference in the rate of occurrence of neurological and autonomic symptoms between cases prescribed and not prescribed antipsychotics. Conclusions: Psychiatric input is imperative for both acute and longer-term management of anti-NMDAR encephalitis. Primary symptomatic treatment should remain immunotherapy and surgery. Antipsychotic medications have particular value in managing agitation and aggression. Potential side effects from antipsychotic treatment are difficult to differentiate from progression of anti-NMDAR encephalitis but there was no evidence in this cohort of increased antipsychotic sensitivity. Treatment with psychotropic medication should be individualised and adjusted during the course of the illness. [ABSTRACT FROM AUTHOR]

Anti-NMDAR encephalitis most commonly presents to psychiatric services, so early identification of this disorder is essential. We aim to validate the two screening criteria (Scott et al. and Herken and Pruss) which have been proposed to identify first episode psychosis patients who should have anti-NMDAR antibody testing. The performance of the screening criteria were assessed using anti-NMDAR encephalitis cases published in the literature, and antibody positive and negative cases from a state-wide cohort (Queensland, Australia). Sensitivity, specificity and area under receiver operator characteristic curve analysis was performed. There were 258 anti-NMDAR encephalitis cases and 103 control cases, which demonstrated high performance of both Scott et al. "screening recommended" criteria (sensitivity 97.3%, specificity 85.4%, AUC 0.914) and Herken and Pruss "yellow flags" criteria (sensitivity 91.5%, specificity 83.5%, AUC 0.875). These criteria remained accurate when neurological variables were excluded, and in cases without psychosis. The Scott et al. "screening not recommended", and Herken and Pruss "red flags" criteria did not demonstrate clinical utility for first episode psychosis case screening. The screening criteria with good performance identify an atypical picture of psychiatric presentation with increased risk of anti-NMDAR positivity prior to overt neurological symptoms or investigations and may be beneficial to include in the routine psychiatric assessment process. • Screening criteria for anti-NMDAR encephalitis demonstrates high clinical utility. • Screening criteria remain accurate without neurological symptoms or investigations. • Anti-NMDAR encephalitis screening should form part of routine psychiatric assessment. [ABSTRACT FROM AUTHOR]