A young man with convulsive laughter. / En ung mann med krampaktig latter.

BACKGROUND: Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) can manifest with a wide range of neurological and psychiatric symptoms. CASE PRESENTATION: A previously healthy man in his late twenties was admitted several times over the course of half a year. He had acute episodes of reduced consciousness, involuntary movements and psychotic symptoms (e.g. hallucinations and delusions). Initial examinations were normal except for a positive urine drug screen (tetrahydrocannabinol), and the patient was diagnosed with cannabinoid intoxication. During the next admission cerebrospinal fluid analysis showed mild pleocytosis. Screening for anti-neuronal antibodies was negative, but anti-thyroid peroxidase antibodies were detected in serum and cerebrospinal fluid. He was successfully given steroid treatment on a tentative diagnosis of SREAT, but relapsed when the steroids were discontinued. After receiving a prolonged steroid treatment with gradual dose reduction over a year, he remains symptom-free 18 months after treatment discontinuation. INTERPRETATION: The diagnostic delay might have been mitigated with an earlier inclusion of neuroimmunological disorders in the differential diagnosis. Unexplained pleocytosis in the cerebrospinal fluid in the presence of paroxysmal neuropsychiatric symptoms should trigger an investigation that includes autoimmune encephalopathies.

The significance of anti-neuronal antibodies for acute psychiatric disorders: a retrospective case-controlled study.

BACKGROUND: The clinical significance of anti-neuronal antibodies in patients with psychiatric disorders, but without encephalitis, remains unknown. In patients admitted to acute psychiatric inpatient care we aimed to identify clinical features distinguishing anti-neuronal antibody positive patients from matched controls. RESULTS: Patients who were serum-positive to N-methyl D-aspartate receptor (NMDAR) (n = 21), contactin-associated protein 2 (CASPR2) (n = 14) and/or glutamic acid decarboxylase 65 (GAD65) (n = 9) antibodies (cases) were age and sex matched (1:2) with serum-negative patients from the same cohort (controls). The prevalence and severity of psychiatric symptoms frequently encountered in NMDAR, CASPR2 and GAD65 antibody associated disorders were compared in cases and controls. NMDAR, CASPR2 and GAD65 antibody positive patients did not differ in their clinical presentation from matched serum negative controls. CONCLUSION: In this cohort, patients with and without NMDAR, CASPR2 and GAD65 antibodies admitted to acute psychiatric inpatient care had similar psychiatric phenotypes. This does not exclude their clinical relevance in subgroups of patients, and studies further investigating the clinical significance of anti-neuronal antibodies in patients with psychiatric symptomatology are needed.