We report a 47-year old traumatic brain injury male patient who was treated for the rigidity and tremor with sinemet (carbidopa⁢levodopa) and artane (trihexyphenidyl). He came to the emergency room ten days after the stopping of sinemet. Acute onset of increased obtunded, immobile, rigid, deep coma, and minimal response to a deep pain was presented. There was no evidence of the focal neurological signs. Over the next two days, he awoke with a normal mental status. His muscle tone become normal and he returned to home without residual medical problems or complications.

We report a serotonin syndrome in a traumatic brain injury patient who was treated with sinemet and artane, which resulted in a dysregulation of serotonin activity.