What is Ulnar Nerve Entrapment at the Wrist?
The ulnar nerve, along with the radial and median nerves, is one of the three major nerves of the arm.  It supplies sensation to most of the hand muscles, as well as to much of the forearm.  It runs up of the hand under the ring finger, branching at a point just below the thumb to extend into the little finger and across the palm.

Less common than cubital tunnel syndrome, the entrapment of the ulnar nerve as it passes through the bony passageway along the inside of the elbow, is the entrapment of the ulnar nerve at the wrist.  Entrapment implies that the normal space of the nerve is disturbed, resulting in a pinching of the nerve.

Causes of Ulnar Nerve Entrapment at the Wrist?
If you have changes in sensation to the muscles in the hand (except for the muscle used to control the thumb), this may be the result of sensory and/or motor (muscle) nerve compression.  Sometimes it is difficult to pinpoint the exact cause of the problem. 

A rare condition, entrapment of the ulnar nerve at the wrist is usually the result of a space-occupying lesion such as a ganglion cyst, a lipoma, or ulnar artery aneurism.  Repetitive trauma, such as operating a jackhammer, sometimes causes this condition.  It can also occur as a result of using the bone of the hand as a hammer.  Nerve compression is more common in people with arthritis, alcoholism, diabetes, and/or thyroid problems.

Symptoms of Ulnar Nerve Entrapment at the Wrist?
Pain is not usually a symptom of ulnar nerve entrapment at the wrist.  Most patients report weakness and increasing numbness, symptoms that may be the result of direct pressure on the outside edge of the hand.

Depending on the location of the problem, ulnar nerve entrapment at the wrist produces sensory and/or motor changes to the hand.  The most common of these is a tingling sensation over the ring and little fingers, as well as the loss of sensation at the tip of the little finger.  There may be signs of muscle atrophy, or weakness of the muscles uses to spread the fingers apart.  Dry, pale skin over the little finger and half of the ring finger is also suggestive of chronic nerve irritation.

You may experience a general weakening of the motor function of the hand, causing you to drop things or have difficulty opening jars.  You may have a hard time coordinating your fingers while typing or playing the guitar, piano, or violin.  The problem usually worsens with activities or occupations that are practiced over an extended period of time.

Treatment of Ulnar Nerve Entrapment at the Wrist?
Your doctor will examine your hand and ask about your medical history, including previous or ongoing conditions of the hand, wrist, or arm.  A test that is used to detect ulnar nerve entrapment at the wrist is known as Tinels sign, which involves testing for tingling in the ring and little fingers. 

Your doctor will look for indications of muscle tissue wasting in the hand, particularly in those spaces that open when you spread your fingers.  Nerve conduction studies help differentiate this condition from problems of the ulnar nerve that originate at the elbow.  Your doctor will also need to rule out the possibility of carpal tunnel syndrome, ulnar artery thrombrosis in the hand, and other peripheral conditions that may result from arthritis, diabetes, alcoholism, or hypothyroidism.

Nonoperative treatment of this condition involves making changes in your routine that relieve external pressure on the ulnar nerve.  This may include making an occupational change.  Padding or a change in position while working at a computer keyboard can help if the problem is caused by resting the hand in such a way as to apply consistent pressure on the nerve.  It is important to carefully manage contributing medical conditions such as diabetes and arthritis.

Surgery is required in most cases of ulnar nerve entrapment at the wrist. The surgeon uses an operating microscope (magnifying glasses) to show detail and correct the cause of nerve compression, removing a lipoma, ganglion cyst, or other small tumor.  An experienced hand surgeon should perform this surgery.  It can usually be done on an outpatient basis, using local anesthetic.

Patients who have constant numbness, severe weakness, or muscle wasting may have scar tissue inside the nerve.  In these cases, micro-surgical release of scar tissue in the nerve is performed, again with the aid of magnifying glasses or an operating microscope.  The outer wrapping of the nerve is opened and the scar tissue within the nerve is freed.

Recovery from surgery typically occurs in two phases.  First there is the immediate release of pressure on the nerve, with a marked improvement in blood flow.  By the time sutures are removed, you will often notice some positive change in the sensation of numbness and tingling of the fingers.  Nerves that have been scarred or degenerated take longer to heal.

Ulnar nerve fibers regenerate from the elbow, through the forearm and hand to the fingertips.  This is a long process and cannot be hastened.  Gripping strength in the muscles of the forearm takes about 4 to 5 months to show improvement.  Neural regeneration in the hand and fingers tends to take 1 to 1 ½ years.  The process is slower in older individuals and in those who have experienced severe neuromuscular damage.

Your doctor will make recommendations for post-operative rehabilitation, including medication, massage, and therapeutic exercise.  There may be some sensory loss due to the injury of small nerves, but these areas frequently diminish in size over time.  Nerve regrowth may be associated with the same sensation of pain that is experienced when your leg and foot come back to life after falling asleep.  Post-surgical pain lasting longer than six weeks requires further evaluation.

Successfully treated, ulnar nerve entrapment at the wrist should eventually result in a return of sensation to the ring and little fingers, as well as increased grip and pinch strength in the hand.