In pediatric autoimmune encephalitis, name one common antibody and typical presenting neurologic features?

• A. Anti-GAD antibodies; seizures only
• B. Anti-NMDA receptor antibodies; psychiatric symptoms, seizures, movement disorders, and autonomic instability
• C. Anti-VGKC antibodies; ataxia
• D. Anti-AQP4 antibodies; optic neuritis

Answer: (B)

The main idea is recognizing that anti-NMDA receptor antibodies are a common cause of pediatric autoimmune encephalitis, and the typical presentation blends neuropsychiatric symptoms with seizures, movement problems, and autonomic instability. In children, this syndrome often follows a viral-like prodrome and then features such as behavioral changes or psychosis, seizures, abnormal movements (like orofacial dyskinesias or chorea), and autonomic signs (fluctuating heart rate and blood pressure, breathing changes). This combination strongly points to anti-NMDA receptor encephalitis and leads clinicians to test for those antibodies in CSF or serum, with immunotherapy often helping.

Other antibodies are linked to different autoimmune CNS conditions and don’t fit this classic pediatric encephalitis picture as neatly: anti-GAD more typically associates with stiff-person–type phenomena or autoimmune epilepsy rather than the full encephalitis syndrome; anti-VGKC–complex antibodies can cause limbic encephalitis but ataxia isn’t the defining cluster in kids; anti-AQP4 is tied to neuromyelitis optica spectrum disorders with optic neuritis rather than the prominent encephalitis presentation described here.