Content Reviewers:Antonia Syrnioti, MD, Lisa Miklush, PhD, RNC, CNS, Ashley Mauldin MSN, APRN, FNP-BC, Gabrielle Proper, RN, BScN, MN
Let’s start with a bit of anatomy and physiology. The carpal tunnel is a rigid canal in the wrist, created by a sheet of fibrous tissue forming its roof, and the carpal bones forming the floor. The tendons of forearm muscles run through this canal, as well as the median nerve. The median nerve supplies motor, sensory, and autonomic innervations to the thumb, index, and middle fingers, in addition to the palmar aspect of the ring finger.
Alright, now the cause of carpal tunnel syndrome is not clear, but there are a number of risk factors, including jobs and activities that involve repetitive movement of the wrist, such as musicians, carpenters, excessive cell phone use, and certain sports, such as golf, tennis, or racquetball. Median nerve compression is generally more common in clients who are assigned females at birth since they tend to have a smaller carpal tunnel. Hormonal imbalance, which can occur during the premenstrual period, pregnancy, and menopause, can also increase the risk for carpal tunnel syndrome. Other risk factors include conditions that may cause swelling inside the carpal tunnel, including diabetes mellitus, peripheral vascular disease and rheumatoid arthritis, as well as acromegaly, which is when excessive growth hormone causes excessive growth in the adult bones and tissues, which can narrow the carpal tunnel.
Regardless of what triggers carpal tunnel syndrome, pathology-wise, there’s increased pressure inside the carpal tunnel, which results in obstruction of venous outflow. This leads to fluid moving from the blood vessels and into the carpal tunnel, which increases the pressure even more, ultimately causing median nerve compression.
In terms of clinical manifestations, clients with carpal tunnel syndrome typically present with pain and in the thumb, index, and middle fingers, and the radial half of the ring finger, as well as clumsiness in fine hand movements. These symptoms are typically worse at night and they may even awaken the client from sleep, and they are often relieved by shaking out their hands.
The diagnosis of carpal tunnel syndrome starts with the client's history and physical assessment, which includes two tests. The first is the Phalen maneuver, where both wrists are flexed to 90 degrees, and maintained in that position for more than one minute. When the symptoms of carpal tunnel syndrome are reproduced, the test is considered positive. The second is the Tinel test, which is performed by repeatedly percussing firmly over the carpal tunnel, and if carpal tunnel symptoms appear, that’s a positive test. To confirm the diagnosis of carpal tunnel syndrome, electrophysiological testing of the median nerve is used to assess the degree of nerve damage.