Carpal Tunnel Syndrome
Does your hand seem to fall asleep but also have aching pain? Have you noticed your grip strength is decreasing and at times you are dropping things? Does the pain wake you up at night and you shake your hand in an attempt to obtain some relief? You may have a condition called “carpal tunnel syndrome”.
What is a syndrome? A syndrome is a group of symptoms that collectively indicate or characterize a disease. What is the carpal tunnel? The wrist is made up of 8 little carpal bones. They act like ball bearings.
It is this arrangement that permits the wide range of motion at the wrist. On cross section they are arranged like an arch which is closed on the palmar side with a very a strong ligament, “carpal ligament”. The space enclosed by the bones and ligament is called the carpal tunnel.
What are the characteristics or symptoms of carpal tunnel syndrome? The patient at first has intermittent symptoms that become more severe and constant with time. The middle finger is most frequently the first area to have characteristic numbness and achy pain. Often the thumb becomes weaker and weaker.
Patients find themselves dropping things because of a progressively weakening thumb. Often the mass of muscles in the palm at the thumbs base lose the roundish appearance and become flat.
What causes these symptoms and findings? The structures that pass through the tunnel are the long flexor tendon to the thumb, and the long and short flexor tendons to the other four digits. Also the very important Median nerve passes through the tunnel. The Median nerve is called a mixed nerve because it contains nerve fibers that carry sensation back to the brain (sensory nerve fibers) and nerve fibers that go from the brain to the muscles at the base of the thumb for their control (motor control nerve fibers).
The tendons are covered with lubricating membranes called synovium. If this membrane becomes inflamed it becomes hyperplastic and increases its volume, this condition is called synovitis. There is no room for this increased volume of synovium. As a result pressure increases in the carpal tunnel compromising the internal circulation of the Median nerve. The nerve is located right up against the ligament on the thumb side of the tunnel. The nerve´s circulation is compromised most severely on the side that contacts the ligament. If that area contains mostly sensory nerve fibers the patient has mostly sensory symptoms. If it contains mostly muscle controlling fibers the symptoms are mostly related to the weakened and painful thumb.
What are some of the causes of this synovitis? Repetitive motions of the hand, females doing duties that should be done by larger hands (such as the repetitive grasping of large bundles of letters in the post office), pregnancy, diabetes, rheumatoid arthritis, myofascitis that sometimes follows severe hand injuries, menopausal women, etc.
In the early phases of this problem, symptoms are usually intermittent, and it is treated by the injection of steroids in the carpal tunnel, resting the hand, wearing splints that immobilize the wrist in a neutral to slightly extended position, limiting salt intake and taking diuretics may stop the proliferation of the synovium. This has been called stage I. In stage II protein in the swollen synovium has organized into fibrous connective tissue. At this stage your symptoms are more or less constant.
Portions of the nerve are starting to die due to loss of circulation. If repeated injections are performed in an attempt to treat Stage II, the acetate in the repository steroid accumulates in the tissues and only makes matters more difficult when the patient finally has the surgical release. Surgery should be done to release the pressure on the nerve. This is especially true if the thumb’s muscles are weakening. Motor nerves have a specialized structure called the motor endplate.
If this structure degenerates it may never repair itself after the pressure is released and circulation is restored to the nerve. Stage III is where this has become chronic and the nerve has significant areas that have degenerated. When operated the nerve is white, thinned and has become flat. I have seen many people who have been treated “conservatively” with therapy and are only referred to a surgeon when things have progressed to where only a limited return of function is possible. This is tragic. Many insurance companies encourage this kind of care. In stage II and III the “conservative” treatment is surgery.
When I perform this surgery I cut the ligament and remove the synovium from the flexor tendons. If the nerve does not “pink up” after the pressure is released (after the ligament is cut), I will cut the fibrous sheath that surrounds the nerve (perineurium) to aid in restoring the nerves circulation. The only way you can see to do the above is to do what is called an open release of the nerve.
This is where the skin is incised and all the structures down to and including the carpal ligament are cut. There is another school of thought on how this release should be performed. They believe that doing the release as an endoscopic procedure is best. I have performed it endoscopically and abandoned it after about 9 months because the patients had more pain, took longer to return to work and at least 50 % had recurrence of their carpal tunnel syndrome in about 6 months. Another detail of my procedure is to place a small closed suction drain in the tunnel. I am amazed by how much serum and blood is removed in the first 72 hours.
If this material was left for the body to absorb it would create significant inflammation. Inflammation is what created the problem in the first place. I want to do anything possible to eliminate it as the wound heals.
The following are some questions commonly asked by patients:
When can I go back to work?
In about 2 weeks if you do not do heavy lifting. If you do heavy lifting you can return to those duties in 5 to 6 weeks if you wear a wrist brace to keep your wrist in a neutral position for an additional 4 weeks.
How severe is the postoperative pain?
With the open technique it is minimal and of short duration. When I did the procedure with the endoscopic approach my patients had significant pain for several weeks.