LAUSR

Figure 1 shows an MRI brain FLAIR sequence coronal image with increased signal intensity within the right hippocampus (arrow). The MRI scan demonstrated increased T2 and FLAIR signal in components of the limbic system (amygdala, hippocampus) on the right, without contrast enhancement or diffusion restriction. This is consistent with a diagnosis of encephalitis. In our patient, inflammatory markers and electrolytes were normal. There was no CSF pleocytosis or elevated protein, but oligoclonal bands were present. Antibodies against the N-methylD-aspartate receptor (NMDAR) were detected in serum and CSF. Given her age and gender, a pelvic MRI was also performed. This demonstrated a 4.1 × 2.5 × 2.8 cm heterogeneous mass arising from the right ovary. It was removed surgically, and the diagnosis of ovarian teratoma was confirmed on histology (Fig. S1, Supporting Information). In addition to sedative, antipsychotic and anticonvulsant medication, the patient was treated with a course of high-dose intravenous methylprednisolone, two daily doses of intravenous immunoglobulin, rituximab and a prolonged oral prednisolone taper. After removal of the teratoma, her condition remained severe, and she was treated with 5 s-daily double-volume plasma exchanges. The need for intensive general and psychiatric care was prolonged, but she ultimately made a full recovery over several months. The clinician–family relationship was strengthened by the identification and removal of the teratoma, which the family interpreted as the exorcised djinn. Autoimmune encephalitis (AI) is a rare but important cause of acute psychosis. Patients may present with psychiatric symptoms, seizures, movement disorders and autonomic instability. Some neurologists have hypothesised that it may account for historical reports of ‘demonic possession’. In AI, antibodies develop against receptors and cell surface proteins in the central nervous system, resulting in disruption of neurotransmission. The NMDAR is the most common identified target, accounting for around 20% of children with encephalitis of unknown aetiology. Neuroimaging can be normal or can show non-specific evidence of encephalitis. Although NMDAR AI was first described as a paraneoplastic syndrome associated with ovarian teratoma in young women, tumours are found in <10% of pre-teens. The significance of the association is that symptoms are often refractory until the teratoma is removed. AI is usually responsive to immunotherapy, which improves prognosis; however, up to 25% of cases relapse.