Clinical reasoning: a 14-year-boy with spells of somnolence and cognitive changes.

SECTION 1 A 14-year-old boy presented for admission after repeated episodes of lethargy and cognitive changes. He had a history of childhood absence epilepsy that had resolved with antiepileptics discontinued 1 year prior to presentation. Two months prior to admission, the patient had a febrile illness with headache and diarrhea that lasted a few days. It was attributed to a nonspecific viral infection, and he recovered quickly. Over the ensuing days, however, he developed increasing sleepiness, cognitive slowing with difficulty concentrating, and an illdefined abnormal perception. He stated feeling that “things were not right, it is as if I am not here.” His parents reported changes in appetite that included hypophagia alternating with hyperphagia, as well as repeated purposeless behaviors such as tapping his fingers and verbal perseveration. His speech was described as “baby talk,” as if he had regressed. This progressed to hypersomnolence, sleeping more than 15 hours/day.