Altered Mental Status in a Teenager

A 13-year-old Hispanic male presented to the emergency department (ED)3 with an altered mental status (AMS) after a 4-day history of nausea and vomiting. Values for electrolytes, glucose, blood urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, calcium, and a complete blood count were all within their reference intervals. The patient's symptoms were treated with intravenous fluids and an antiemetic medication. He felt better and was discharged home. At home, the patient continued to vomit everything he ate or drank, even after receiving his antiemetic medication. Two hours after taking the antiemetic, he began saying things that did not make sense. He went to sleep, but he woke several hours later screaming, agitated, and in need of restraint in order not to hurt himself.The patient was brought back to the ED 40 h after his initial presentation. He was obtunded, randomly reacting to touch, but not responsive to voice. He was admitted to the pediatric intensive care unit. He received both acyclovir for possible herpes encephalitis and cefotaxime until the cause of his symptoms was determined not to be sepsis. Tests of a sample from a lumbar puncture showed normal values for glucose, protein, and cell count, and antivirals and antibiotics were discontinued. The patient also received lorazepam for agitation and midazolam for sedation before undergoing a head computed tomography scan, the results of which were normal. A comprehensive urine drug screen showed only benzodiazepines from the midazolam.The patient's medical history indicated presentation at age 11 with a 3-day history of emesis and changes in mental status. At that presentation, he was sleepy, was difficult to arouse, and showed decreased muscle tone. The results of a head computed tomography scan at that time were essentially normal. The results of laboratory tests, including those for electrolytes, glucose, …