A 71-year-old man was admitted to the hospital with subarachnoid hemorrhage caused by a cervical dural arteriovenous shunt. During surgery, the patient developed acute hypotension and bradycardia, probably caused by surgical compression of the medulla oblongata. During posterior fossa and upper cervical surgery, monitoring cardiovascular, respiratory, and evoked potential parameters is advocated. In the current case, only cardiovascular monitoring detected alteration of brain stem function. Anesthesiologists should be aware that surgical manipulation of the dorsal medulla might cause hemodynamic changes and expose patients to danger. Through close cardiovascular monitoring we can rapidly detect changes in vital signs, which allows prompt intervention to prevent irreversible neurologic deficits and potentially catastrophic patient outcome.