Potential Risks Potential risks include loss of confidentiality or mild discomfort associated with the pinprick for sensory testing. Risks that are involved with administration of ropivacaine are primarily damage to surrounding tissues, including nerves, and may cause bleeding or infection from injection or an unknown allergy to ropivicaine that develops during the administration of the drug. There are no additional physical or psychological risks that may result from participation in this research protocol since patients will have determined that they desire perineural blockade before study inclusion is even proposed.