We present a case of a 16 year old boy with a history of Attention Deficit Hyperactivity Disorder (ADHD) and Learning Difficulty, who was admitted to the pediatric ICU with altered mental status at the end of April 2024. His symptoms started with hypersomnia, irritability, unusual aggressive behavior, hallucination all of which were disabling at the time. Shortly before these, he developed flu-like symptoms and he tested positive for Influenza A. Serology, initial lumbar puncture and MRI were unremarkable. EEG showed diffuse slowing but no epileptiform discharges. He was started on pulse dose steroid treatment for suspected autoimmune or influenza encephalitis, and his mental status gradually returned to baseline. His symptoms returned in mid-May, and workup including CSF studies, MRI, and EEG were repeated and remained unremarkable. He was treated with IVIG and steroids, unfortunately complicated by post-IVIG hemolysis, after which symptoms resolved. The patient had a third similar episode at the beginning of July with repeated unremarkable workup and subsequent complete resolution, and he has remained asymptomatic since. 

This case demonstrates a probable diagnosis of Kleine Levin Syndrome. Extensive workup and evaluations by multiple specialists remained unremarkable repeatedly, and it is unclear if steroid and IVIG treatment lead to improvement or if the improvement would have happened spontaneously. This highlights the importance of considering this diagnosis to avoid potentially detrimental or prolonged treatment courses and bring understanding to this disorder.