Ulnar nerve entrapment is an extremely common injury to a nerve that runs through the arm into the fingers on the inside of the hand. Most people can make a full recovery. While this condition is usually not serious, it can have permanent consequences, including paralysis and loss of feeling, if not treated promptly. Getting diagnosed properly is the key to avoiding long-term loss of function. This may be done with a physical exam, a series of X-rays or nerve conduction studies where needles are inserted into the muscles around the ulnar nerve to check functioning.
The key to understanding this condition is understanding the ulnar nerve. The ulnar nerve is one of the arm’s major nerves and is part of the brachial plexus nerve system. It gets its name from its location near the ulna bone, a bone in the forearm on the side of the pinky finger. It starts in the neck and travels through the shoulder down the arm and into the wrist and fingers. It provides sensation to the forearm and 4th and 5th fingers. It also stimulates the flexor muscles of the hand allowing them to bend and move.
The ulnar nerve runs the entire length of the arm and there are several places along the nerve that can be compressed or irritated. This compression is known as ulnar nerve entrapment. It is the second most common entrapment nerve pain in the upper body. It happens most often at or near the elbow, particularly on the inner part of the elbow. This is known as cubital tunnel syndrome. It can also happen at or near the wrist or anywhere between the wrist and elbow or elbow and shoulder.
This compression should be differentiated from cervical radiculopathy involving the C8 nerve root, which may mimic ulnar nerve compression. It should also be remembered that cervical radiculopathy and ulnar nerve compression might coexist in the so-called Double Crush Syndrome. This occurs most commonly with ulnar nerve compression at the wrist or carpal tunnel syndrome.
The ulnar nerve runs through several areas of the arm that can bend and cause pressure on the nerve. The single most common cause is compression on the ulnar nerve. This may be the result of leaning on the elbow for an extended period of time, fluid buildup in the elbow, bone spurs in the elbow, arthritis in the elbow or wrist, swelling in the elbow or wrist and any activities that cause a person to bend or straighten the elbow joint repeatedly.