Evaluation of the hemodynamic response of intravenous clonidine versus ropivacaine scalp block to insertion of scalp pins in neurosurgical patients

The application of the skull-pin head-holder, used to stabilize the head during neurosurgical procedures, produces an intense nociceptive stimulus and results in abrupt increases in blood pressure and cerebral blood flow under general anesthesia. Different anesthetic and pharmacologic techniques, including local anesthetics, narcotics, antihypertensives, and deepening of anesthesia with inhalation anesthetics, have been used to blunt this deleterious effect with variable success.