Evaluation of the proposed anti-N-methyl-d-aspartate receptor encephalitis clinical diagnostic criteria in psychiatric patients.

OBJECTIVE: The gold standard for diagnosing anti-NMDAR encephalitis is demonstration of the antibody in CSF. Clinical diagnostic criteria have been proposed for when this is not available in a timely manner which is evaluated, in this study, for a psychiatric population. METHODS: This study retrospectively assessed the proposed criteria in patients presenting to psychiatric services for the first time with known anti-NMDAR antibody status. Antibody-positive cases were derived from the literature (conception to December 2019) and a state-wide (Queensland, Australia) cohort. Antibody-negative cases were derived from a service-wide (Metro South, Queensland, Australia) cohort of psychiatric cases which underwent antibody testing for routine organic screening. Sensitivity and specificity were calculated at 1 week following admission and the point of discharge. RESULTS: The proposed criteria were applied to 641 cases (500 antibody-positive and 141 antibody-negative), demonstrating a sensitivity which increased from around 19% after 1 week to 49% by the point of discharge. Specificity was 100% at both time points. The mean average time to become positive using the proposed criteria was 19.5 days compared to 34.9 days for return of antibody testing. CONCLUSIONS: High specificity of the proposed criteria, seen in this study, suggests that cases which are positive can be considered for expedited commencement of treatment. However, if clinical suspicion is high despite criteria being negative, it is essential to test CSF for anti-NMDAR antibody.

Antiglycine receptor antibody related disease: a case series and literature review.

BACKGROUND AND PURPOSE: Antibodies to glycine receptors (GlyR-Abs) were first defined in progressive encephalopathy with rigidity and myoclonus (PERM) but were subsequently identified in other clinical presentations. Our aim was to assess the clinical associations of all patients identified with GlyR-Abs in Queensland, Australia, between April 2014 and May 2017 and to compare these to cases reported in the literature. METHODS: A literature review identified the clinical features of all published GlyR-Ab-positive cases through online databases. A case series was undertaken via collection of clinical information from all patients diagnosed or known to immunology, pathology or neurological services in Queensland during the study period of 3 years. RESULTS: In all, 187 GlyR-Ab-positive cases were identified in the literature. The majority (47.6%) had PERM, 22.4% had epilepsy, but the remaining 30% included mixed phenotypes consisting of cerebellar ataxia, movement disorders, demyelination and encephalitis/cognitive dysfunction. By contrast, in our series of 14 cases, eight had clinical presentations consistent with seizures and epilepsy and only three cases had classical features of PERM. There was one case each of global fatiguable weakness with sustained clonus, laryngeal dystonia and movement disorder with hemiballismus and tics. The rate of response to immune therapy was similar in all groups. CONCLUSION: Antibodies to glycine receptors are linked to a spectrum of neurological disease. The results of the literature review and our case series suggest a greater relationship between GlyR-Abs and epilepsy than previously reported.