Limbic encephalitis with phenotypic NMDA receptor antibodies in patients with de novo diagnosis of Systemic Lupus Erythematosus. Case report

Abstract Malignancy-associated limbic encephalitis was first described in 1968. Since then, cases have been reported in association with the Herpes Simplex virus, Hashimoto's encephalopathy, lupus, Sjogren's syndrome and paraneoplasias. A syndrome with prominent psychiatric symptoms was described in 2005: consisting of memory loss, reduced level of consciousness and central hypoventilation in four young women with ovarian teratoma and antibodies against an antigen highly expressed in the hippocampus. Shortly afterwards, these patients were found to have autoantibodies against NMDA receptor NR1 (GluN1) subunit. This discovery has been of the greatest importance in clinical practice since it identifies a devastating, life-threatening neurological disorder that is treatable. In 2007, it was recognised as a nosologic entity and today it is the most common cause of autoimmune encephalitis after disseminated subacute encephalomyelitis. Case report presentation of a patient exhibiting almost all the clinical symptoms described in the syndrome characterised by NMDA receptor-associated encephalitis. Moreover, a neuroradiological correlation was found, with involvement of limbic structures seen on brain magnetic resonance imaging. Reasonable exclusion was made of the presence of neoplasia and neuroinfection, and clinical and immunological criteria of systemic lupus erythemathosus were found, helping with the categorisation of lupus-associated limbic encephalitis. Mortality due to limbic encephalitis is 25%, and 75% of patients may have permanent sequelae. Given adequate response to immunosuppressive therapy, early and correct recognition are critically important.