Background:

Autoimmune encephalitis occurs as a subacute condition with a strong infectious association in children. In the last 20 years, the frequency of non-infectious cases has increased significantly.

Clinical case:

A previously healthy eight-year-old male child with normal neurodevelopment, without a history of consanguinity, manifested progressive neurological deterioration with autoimmune encephalitis-limbic encephalitis up to hypothalamic dysfunction.

Conclusion:

In the mentioned case, it was documented that an inborn error of the immune system generated a severe neurological clinical picture, with permanent and irreversible damage, secondary to lack of immunological memory in the broad clinical context of a common variable immunodeficiency.