Autoimmune Encephalitis

This cranial MRI is from a young woman who presented with low-grade fever, confusion, visual hallucinations and status epilepticus. Significant orofacial dyskinesias and autonomic dysfunction was also noted. Lumbar puncture was performed and cerebrospinal fluid (CSF) revealed mild lymphocytic predominant leukocytosis and slightly elevated protein. CSF glucose was within normal range and CSF for microbiological studies including PCR for herpes simplex encephalitis were unrevealing. Cerebral MRI revealed a hyper-intense signal involving the right medial temporal lobe and hippocampus  in the FLAIR (Figure 1) and T2 sequences (Figure 2), compatible with limbic encephalitis. Her status epilepticus was controlled with multiple anti-epileptic agents and she was initially treated empirically as viral encephalitis with intravenous acyclovir. CSF and serum for anti-NMDA receptor antibodies were subsequently noted to be significantly positive. A diagnosis of autoimmune encephalitis due to anti-NMDA receptor antibodies was made. She was started on immunotherapy including high dose intravenous then oral steroids as well as plasmapharesis. A search for underlying malignancy was made and a right-sided ovarian teratoma was found. She was referred to the Gynaecologists for excision of the ovarian teratoma. Her steroid treatment was subsequently replaced by azathioprine, a steroid-sparing agent, and her condition gradually improved over the subsequent few weeks.