Complex sentence: Prior to the development of a symptom complex that is specific to anti-NMDA receptor encephalitis, patients may experience prodromal symptoms, including headaches, flu-like illness, or symptoms similar to an upper respiratory infection.
Split into simpler sentences: Prior to the development of a symptom complex that is specific to anti-NMDA receptor encephalitis, patients may experience prodromal symptoms. These could include headaches, flu-like illness, or symptoms similar to an upper respiratory infection.