The median nerve originates from the brachial plexus, a network of nerves in the neck and shoulder. It travels down the arm, forearm, and into the hand. This nerve enables wrist, thumb, and first three finger movement, forearm rotation, and sensation to the palm side of the thumb, index, middle, and half of the ring finger.
Understanding Median Nerve Compression
Nerve compression occurs when sustained pressure disrupts a nerve’s normal function, interfering with its ability to transmit electrical signals. This disruption leads to a range of noticeable symptoms in the areas supplied by the nerve.
Individuals often experience numbness or tingling in the thumb, index, middle, and part of the ring finger. Pain can also manifest in these fingers or radiate up the forearm. Muscle weakness may develop, making it difficult to grasp objects or perform fine motor tasks.
Common Causes of Median Nerve Compression
The most frequent cause of median nerve compression is Carpal Tunnel Syndrome (CTS). The carpal tunnel is a narrow passageway formed by wrist bones and a strong ligament. Through this confined space, the median nerve travels alongside nine flexor tendons responsible for finger movement.
Compression arises when swelling or inflammation within this tunnel reduces the available space, putting pressure on the median nerve. Wrist fractures or dislocations can alter the tunnel’s structure, while inflammation from arthritis or fluid retention can also contribute. Less common causes include cysts, tumors, or underlying health conditions like diabetes, which increase susceptibility to nerve damage. The nerve can also be compressed at other points along its path, such as in the forearm, a condition known as pronator teres syndrome.
Identifying Median Nerve Compression
Medical professionals employ physical examination techniques to identify median nerve compression. Phalen’s maneuver involves holding wrists in complete flexion, pressing the backs of hands together. If this position reproduces numbness, tingling, or pain in the median nerve’s distribution, it suggests compression. This maneuver increases pressure within the carpal tunnel, which can provoke symptoms if the nerve is compromised.
Another common diagnostic test is Tinel’s sign, where a healthcare provider lightly taps directly over the median nerve at the wrist. A positive Tinel’s sign occurs if this tapping elicits a tingling sensation in the thumb, index, and middle fingers, indicating nerve irritation or damage at that site.
These physical tests help localize the area of compression by replicating the characteristic symptoms. For a more objective assessment, nerve conduction studies (NCS) and electromyography (EMG) may be used. These tests measure the speed and strength of electrical signals traveling through the nerve and the electrical activity in muscles to confirm nerve damage and its severity.