Carpal tunnel syndrome (CTS) is a wrist injury that causes damage to the median nerve, which radiates from the forearm into the hand. The median nerve is responsible for the transmission of impulses to the thumb and the first four fingers of the hand. The median nerve is also the transmitter of impulses to the nine tendons that provide flexion capability to the fingers. The median nerve also provides the nerve transmissions to the muscle group at the base of the thumb.
The carpals are a series of eight bones that connect the forearm to the fingers of the hand. The carpals and the transverse carpal ligament, a thick fiber connective tissue that binds together the bones of the wrist, together create the carpal tunnel, an archway through which the median nerve passes. As the tunnel is a narrow passageway containing the median nerve and tendons, any external pressure or damage to the carpal tunnel, such as a fracture, will often result in the median nerve becoming compressed and irritated, causing a loss of function.
The damage to the carpal tunnel can occur in a number of ways. A common cause of CTS is repetitive strain, such as that associated with occupations in which movements are repeated, or in which particular tools such as hand sanders and grinders are in constant use. Daily computer keyboard use is also a common cause of CTS. In non-athletic scenarios, the CTS usually occur in the dominant hand of the person. In some cases, there is a congenital basis for CTS, whereby the carpal tunnel is unusually narrow. Simple aching from repetition is not a symptom of CTS; the physical restrictions caused by CTS are manifested over a period of weeks or months.
The median nerve will also be damaged through compression in cases of wrist facture, which events can occur through a fall on the wrist, a violent twisting motion to the wrist, or a blow to the wrist. Not all wrist fractures will cause or contribute to a CTS condition, but when the fracture is to one or more of the carpal bones, or the fracture otherwise places pressure on the carpal tunnel, the CTS syndrome may arise. When the median nerve becoming irritated through compression, in addition to pain, the nerve impulses along the median nerve are slowed, causing a loss of performance in functions involving the hand.
The symptoms of CTS are primarily a tingling, numb sensation noticed in the thumb, or the first three fingers of the hand; CTS does not affect the small finger of the hand. Of primary importance to the athlete, the afflicted person will notice a decreased ability to grip objects, and there will be a corresponding loss of fine motor control and other manual tasks.
There are a number of tests that may be performed to isolate CTS from among other causes of the tingling and loss of function in the hand. The Tinel test is performed with pressure being placed on the location of the median nerve, just above the wrist. If a tingling sensation is experienced in the thumb or fingers, the nerve is likely compressed. The Phalen test involves the person extending the arm and flexing the wrist inward; if tingling is experienced, CTS is a strong possibility.
In many cases, when the wrist is fractured, the pressure leading to CTS may reveal itself after the wrist bones are subsequently healed. In such circumstances, the carpal tunnel pressure may be released by way of surgery. An incision is made to the transverse carpal ligament that covers the tunnel through which the median nerve passes into the hand. The carpal bones are separated slightly, and in this fashion a greater space is created for the median nerve, which will serve to alleviate the pressure applied by the tunnel passage to the nerve. In some cases, the CTS condition may be treated by rest and immobilization, that is, placing the arm in a sling or through the use of a wrist brace). Anti-inflammatory medications such as ibuprofen or corticosteroids (a topical anti-inflammatory) may also assist in reducing the amount of swelling or irritation in the median nerve.
Some sports are more prone to wrist fracture than others; CTS is more likely to manifest itself in repetitive wrist movement sports such as rowing, racquet sports, and cycling, or in contact sports in which the wrist has a greater likelihood of exposure to injury through the contact with sticks wielded by opponents, such as ice hockey or lacrosse.