The carpal tunnel, formed by the concave anterior surface of the carpal bones and closed by the flexor retinaculum is a tightly packed with long flexor tendons of the fingers along their surrounding synovial sheaths and the median nerve.
The long flexor tendons to the fingers and thumbs pass through the tunnel and are accompanied by the median nerve. The four separate tendons of the flexor digitorum superficialis muscles are arranged in a way that they give rise to anterior and posterior rows, those to the middle and ring fingers which are present in front of those to the index and little fingers. At the lower border of the flexor retinaculum, the four tendons diverge and get arranged on the same plan. The median nerve is passed between the flexor retinaculum in a restricted space between the floor digitorum superficialis and the flexor carpi radialis.
The Carpal Tunnel syndrome is actually due to compression of the median nerve within the tunnel. This nerve supplies to the fingers.
Signs and Symptoms
The syndrome consists of burning pain or pins or needles along the distribution of the median nerve to the lateral three and a half fingers. It also causes weakness of the thenar muscles. The grip becomes weak and difficult to hold anything, pain radiates to the elbow, complaints of numbness and tingling in the fingers and thumb and movement problem in fingers. But no parenthesis occurs of the thenar eminence because this part of the skin is supplied by the palmar cutaneous branch of the median nerve which passes superficially to the flexor retinaculum.
The exact cause of the compression is difficult to determine, but there is seen a thickening of synovial sheaths of the flexors tendons or arthritic changes in the carpal bones which have led to this syndrome. Other reasons for the syndrome are internal factors which can exert pressure on the median nerve as well as some external factors like tumors or other diseases. It has also been seen that due to continuous and repetitive movements of hands and wrist, this carpel tunnel syndrome ensues. Typing on the keyboard is also thought to be one of the commonest causes.
Other causes include hypothyroidism, diabetes, menopause, alcoholism, bone fracture, rheumatoid arthritis, acromegaly and systemic lupus erythematosus. Certain viruses are also linked in causing this disease. A person who is obese also has a risk of developing this disease.
It is based on complete history and physical examination. There are many orthopedic tests like tinel’s sign or phalen’s test to check this syndrome physically. Other includes x-rays, and nerve conduction velocity etc.
It can be treated by the use of non-steroidal anti-inflammatory drugs like ibuprofen, mefenamic acid etc. Corticosteroids are also helpful. For this condition use of hot and cold compression is also helpful. This condition is dramatically relieved by decompressing the tunnel by making a longitudinal incision through the flexor retinaculum. Other includes avoidance of the work which leads to this condition.
This disease has an overall good prognosis.