Abstract

Anti-N-methyl-d-aspartate (NMDA) receptor encephalitis is a potentially reversible immune mediated disorder, often paraneoplastic and associated with antibodies to the NR1–NR2 subunit of the NMDA receptor. Largely a disorder of young women, its diagnosis is aided by a characteristic clinical syndrome. In light of this we describe a 32-year-old female diagnosed with multiple sclerosis (MS) who presented in 2009 after two separate clinical episodes; left-sided optic neuritis and a right trigeminal nerve sensory disturbance. Magnetic resonance (MR) scan of brain fulfilled Barkhof criteria. In 1998 she suffered a severe encephalitic illness of undetermined aetiology characterised by a viral prodrome, seizures, fluctuating consciousness, oral dyskinesias, catatonia, and mutism. Extensive investigations failed to identify an underlying cause, despite a cerebrospinal fluid pleocytosis of 18 lymphocytes, diffuse slowing on EEG and a normal MR brain. She was treated with antibiotics, acyclovir, steroids, and antiepileptic drugs. After a prolonged hospital admission and neurorehabilitation she has made a complete recovery. Anti-NMDA receptor antibodies measured in 2009 are weakly positive. We suggest the encephalitic illness suffered in 1998 was that of anti-NMDA receptor encephalitis. Natural history and long-term sequelae of this recently described condition remain unknown, and antibodies may remain positive for long periods. This is the first report of a potential association with MS.