Autoimmune encephalitis in an infant: a diagnostic challenge in early childhood.

Autoimmune encephalitis (AE) is a neurological disease mediated by autoantibodies, with the anti-NMDA form being the most common. Its clinical presentation in children is usually less evident than in adults, with a predominance of motor symptoms and an absence of neuropsychiatric symptoms. Early diagnosis is difficult due to a lack of clinical suspicion. We present the case oaf a six-month-old infant with status epilepticus and initial herpetic meningoencephalitis, who later presented with loss of developmental milestones and involuntary movements. The detection of antibodies in cerebrospinal fluid confirmed the diagnosis of anti-NMDA encephalitis. Treatment with glucocorticoids and intravenous immunoglobulin was administered, with a favorable response and progressive recovery. This case highlights the importance of considering AE in infants with loss of developmental milestones and involuntary movements. Early diagnosis and treatment are crucial for a favorable prognosis and prevention of sequelae.