The purpose of this study is to determine the conducting ability of distal extremity nerves after a supraclavicular brachial plexus nerve block (with local anesthetic) has been placed at a more proximal location in the upper extremity.

Inclusion Criteria:

• Male and female military health care beneficiaries 18 years and older, capable of providing informed consent indicating awareness of the investigational nature of the study, in keeping with institutional policy
• Written informed consent must be obtained from each patient prior to entering the study
• Patients must be willing to have a regional anesthetic nerve block placed prior to their scheduled procedure
• Patients must be willing to have neurodiagnostic tests performed prior to placement and after placement of the regional anesthesia nerve block

Exclusion Criteria:

• Refusal to have a brachial plexus nerve block placed
• Refusal to have serial nerve conduction studies performed
• Contraindication for a regional anesthesia nerve block (allergy to local anesthetic, infection at site of injection, elevated coagulation time)
• Presence of conditions affecting the hand or arm (e.g., injury, infection) that might preclude the performance of nerve conduction studies
• Presence of known major abnormalities of nerve conduction, e.g., absent median sensory potential in a patient scheduled for carpal tunnel release
• Presence of conditions affecting the contralateral hand or arm (e.g., injury, infection) that might preclude the performance of sensory and motor studies to test block or absence of a contralateral upper extremity

Male and female military health care beneficiaries age 18 years and older presenting for hand surgery and eligible for a brachial plexus nerve block will be asked to participate in this study.