Deterioro cognitivo subagudo en un paciente con esquizofrenia: a propósito de un caso de encefalitis autoinmunme anti-LGI1

Abstract

Autoimmune encephalitis refers to a heterogeneous group of disorders mediated by antibodies directed against neuronal surface or intracellular antigens. The most common subtypes are associated with NMDA, LGI1, CASPR2, and GABA receptors, among others. Anti-LGI1 encephalitis is typically characterized by a triad of subacute dementia, faciobrachial dystonic seizures, and hyponatremia. We present the case of a 57-year-old man with a history of schizophrenia who developed a four-month subacute cognitive decline accompanied by psychotic symptoms. At first, this clinical picture was interpreted as a decompensation of his preexisting psychiatric condition, and he was admitted to an acute psychiatric unit. There was a known familiar background of dementia, and no other neurological symptoms or hyponatremia were present. During the diagnostic workup, anti-LGI1 antibodies were detected in the cerebrospinal fluid, confirming the diagnosis of autoimmune encephalitis. Then he was transferred to the Neurology department, where he received high-dose corticosteroid therapy, resulting in marked clinical improvement. This case is among the few reported in Spain to date and is notable for its atypical presentation, lacking the classical features of the disease, which can be used to understand and identify early this entity.