Mesencephalic seizure, also known as paroxysmal sympathetic hyperexcitability, is a kind of clinical syndrome which mainly manifested as paroxysmal high fever, hypertension, tachycardia, shortness of breath accompanied by sweating, dystonia and other autonomic nervous dysfunction. As the clinical manifestations are similar to epilepsy, mesencephalic seizure is often misdiagnosed by clinical doctors. Diencephalon attack usually occurs after craniocerebral injury, especially traumatic brain injury, followed by cerebral hypoxia and stroke. Sedative and anti-epileptic treatment during mesencephalic seizures can get satisfactory effects but can not completely improve sympathetic excitation. Dexmedetomidine has sedative, analgesic, sympathetic relief effect. We here first report a successful mesencephalic seizures case who received the Dexmedetomidine as main treatment.