Carpal Tunnel Syndrome

Carpal Tunnel Syndrome

To understand carpal tunnel syndrome, one needs to learn about the basic structures occurring at the wrist and hand level. The basic supporting structures are the bones of the wrist which include the forearm bones, the wrist bones, medically known as the carpal bones, and the bones of the hand. The flexor tendons are the structures that extend from the muscles to the fingers like the strings of a marionette. They allow us to perform the multiple activities during the day. There are three main nerves coming down to the hand to control the muscles and tendons known as motor nerves and it gives us the ability to feel, which are the sensory nerves. The nerve involved with carpal tunnel is known as the median nerve which generally gives sensation of the thumb, index, long and ring fingers. There is also a small branch of the nerve that comes through the muscles as the base of the thumb.

The median nerve involved with carpal tunnel syndrome runs with the tendons in the area appropriately called the carpal tunnel. The bones of the wrist cover this tunnel on three sides and on the palm side, there is a thick ligament called the transverse carpal ligament that forms the groove of the tunnel. It is within this tunnel that pressure builds up that can cause the classic symptoms of numbness and tingling.

Causes of Carpal Tunnel Syndrome

• Idiopathic : Many cases of carpal tunnel have no known cause and are thought to be anatomic abnormalities that make an individual at risk.
• Overuse : There is some information to suggest that overuse of the fingers or wrist or certain positions, for extended periods of time, can contribute to pressure on the nerve.
• Injuries : An injury to the wrist involving bleeding, such as with a fracture, can oftentimes cause increased pressure within the tunnel leading to symptoms either early or late in the course after a fracture or dislocation.
• Medical Conditions : Pregnancy, diabetes and thyroid problems are all known causes of carpal tunnel syndrome .

Understanding Carpal Tunnel Syndrome

In many cases the long-term consequences of numbness and tingling can be prevented through simple modifications. Altering the way one does certain activities, whether be at work, home or at recreation, can significantly improve and sometimes eliminate the symptoms of numbness and tingling.

Medical Interventions

1. Oftentimes wearing a proper splint, time or over the counter medications can significantly help.

• Doctor recommended modalities-prescription medication known as anti-inflammatories can oftentimes help relieve the swelling. Sometimes, an injection of Cortisone can be helpful either temporarily or permanently to improve and eliminate the symptoms associated with this condition. Sometimes, physical therapy can be helpful.
• Scientific studies have not today shown any predictable benefit from vitamins, though there have been anecdotal reports that vitamin B6 is helpful, though studies have not proven that.

How to Diagnose Carpal Tunnel Syndrome

An early, thorough approach is very beneficial to diagnose, cure and prevent ongoing symptoms of carpal tunnel syndrome; one is history. It is very important to obtain a thorough history of other medical conditions, injuries and the characteristics of the condition. It is helpful to write down certain information that you can pass on to the doctor at the time of the examination.

Physical Examination

A thorough examination of the area is very helpful to either rule in or rule out the diagnosis. Most patients do not have textbook-like symptoms and it is important for you and your doctor the look at the characteristics and the physical examination findings. Three commonly used maneuvers are a Tinel's test, where the doctor will tap over the nerve, the second is the Phalen's maneuver, which is performed by flexing the wrist and seeing if this causes characteristic numbness and the third is termed a forearm compression test where wrist pressure is placed over the nerve to determine the distribution of tingling.

Carpal tunnel syndrome is almost like a viselike pressure on the nerve which goes to the tips of the thumb, index, long, and half of the ring fingers.  The nerve involved is called the median nerve.  The condition gets its name because the nerve runs through the tunnel at the wrist called the carpal tunnel.  On three sides, the tunnel is bounded by bone and on the fourth side, there is a thick ligament called the transverse carpal ligament.  The nerve runs with all the tendons up to the fingers and pressure could develop within the tunnel that can give symptoms of numbness, tingling, night pain, and symptoms with activities such as holding a book, driving a car, and brushing your hair. 

Conservative measures in many cases can help diminish the symptoms and cure carpal tunnel syndrome.  Nighttime splints are very helpful, but it is important that the splint should be in the neutral, straight position.  Most splints obtained in the supermarket or pharmacy have a bend of the wrist that extends the wrist back.  For sprains, this may be appropriate but for carpal tunnel, the wrist should be straight.  This maximizes the volume for the nerve.  Second, some physical therapy for nerve gliding exercises can sometimes be helpful but most important, considerations of ergonomics at workstation also is very important. 

One contributing factor to carpal tunnel syndrome is desks or workstations that put significant stress on ones' bodies.  Ergonomics in this context refers to proper body positioning at work.  The therapist can help in designing the proper workstations, especially emphasizing seat and desk height, keyboard and monitor positions.  This can oftentimes help diminish many symptoms of opportunity pain. 

A Cortisone injection is also sometimes useful to confirm the diagnosis and also to help cure carpal tunnel syndrome in some cases.  Studies have shown temporary improvement rates of 80% and permanent improvement rates of 20% to 30% in case of carpal tunnel compression. The length of "temporary" is unfortunately variable and not predictable and can last for days, weeks, months or years.  An injection can often be utilized as a non-operative technique to treat carpal tunnel syndrome.  The therapy modality termed a cold laser is also something we make available to our patients.  A low-level laser light has been shown in European studies, as well as one study at General Motors to help diminish symptoms of carpal tunnel syndrome, cold laser. 

When conservative measures fail, surgery is also an option for a carpal tunnel syndrome with success rates in the 85% to 95% range.  Please see the Carpal Tunnel Surgery section and the section on surgery to review the general risks.

Revised 5/11/10 wh