The median nerve travels through a compartment called the carpal tunnel in the wrist. The ligaments that transverse the nerve are not very flexible. If there is any swelling within the wrist compartment excessive pressure can be put on structures such as the blood vessels and the median nerve. Excessive pressure can constrict bloodflow and cause nerve damage. The symptoms from the compression causes pain, loss of sensation, and decreased function in the hand.Review Date:8/11/2012Reviewed By:Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.