Encephalitis with prominent psychiatric symptoms has been historically referred to as limbic encephalitis. Auto immune conditions associated with malignancies can cause encephalitis (=para neoplastic conditions : e.g. anti-Hu associated with lung cancer, anti-Ma2 associated with testicular cancer and anti-CRMP5/ CV2 in thymoma). In the last decade, it has been shown that antibodies could lead to a similar syndrome in the absence of malignancy.
Antibodies against voltage-gated potassium channels (VGKCs) and antibodies directed against the NR1 and NR2 subunits of the N-methyl-D-aspartate (NMDA) receptor (also known as NMDAR ) can produce encephalitis with psychiatric presentations. It is now understood that antibodies can target a range of neuronal cell membrane antigens. ( NMDAR, VGKC complex, AMPAR, GABA, Glycine receptor, glutamic acid decarboxylase) resulting in various presentations. These conditions present with symptoms that include psychosis, involuntary movements, catatonia, depression, seizures, amnesia, autonomic disturbance etc. Since immunosuppresive therapy can effectively treat this condition it is important that psychiatrists recognise and appropriately investigate these states.
When should psychiatrists consider screening for auto immune encephalitis?
Symptoms that indicate the need for potential screening for autoimmune encephalitis in patients with psychiatric symptoms: sudden-onset paranoid psychosis or rapid deterioration, prodromal headache or raised temperature prior to onset of psychosis, cognitive impairment, catatonia, seizures, autonomic disturbance ,suspected neuroleptic malignant syndrome, hyponatraemia (an indicator of anti-VGKC- complex (LGI1) antibody encephalitis).
Serum antibody assay: Anti-VGKC-complex and anti-NMDA receptor antibodies.
EEG- May show epileptiform activity or slow waves . ( unique pattern described in prolonged cases-‘extreme delta brush’)
MRI- may show medial temporal hyper intensity.
CSF- antibody study- may not be possible due to mental state , raised protein can be non specific, increased WBC and oligolcinal bands could be seen.
ESR, CRP- usually normal
Treatment: Immunotherapy is the choice of treatment. shared management with neurology and psychiatry is strongly advocated.
Summary of the article
Autoimmune encephalitis: a potentially treatable cause of mental disorder: Hugh Rickards, Saiju Jacob, Belinda Lennox & Tim Nicholson. Advances in psychiatric treatment (2014), vol. 20, 92–100 doi: 10.1192/apt.bp.113.011304