Carpal tunnel syndrome

Introduction
Carpal tunnel syndrome is the most common type of entrapment neuropathy in the upper limb. Entrapment neuropathy is a kind of nerve injury which results from repeated compression of a nerve by any external cause or due to anatomical factors in the body (like compression from bony structures, ligaments etc) .This causes pain , numbness and weakness of the affected hand.

What is the cause of carpal tunnel syndrome?
Carpal tunnel syndrome is caused by the compression of the nerve at the wrist joint between the carpal bones(bones in the wrist joint) and a thick band like structure(transverse carpal ligament). The nerve that is compressed is known as median nerve. Median nerve is responsible for the sensation of our hand over the medial side (thumb side-that is thumb, index, middle and part of ring finger). Median nerve carries sensation like pain, pin prick, touch, and heat and cold. In carpal tunnel syndrome, median nerve is compressed resulting in injury to the nerve. The insulation of the nerve called myelin sheath gets degenerated and the signals which pass through the nerve are impaired.

Who are more likely to get carpal tunnel syndrome?
Carpal tunnel syndrome usually occurs in middle aged persons. Females are more prone to get this disease. The ratio of female: male is about 4:1. In 50 percent of the patients both hands are involved, but it is usually worse in one hand. In many cases of carpal tunnel syndrome no specific cause can be identified. But in cases where the young people are involved the following conditions must be looked into.

• Trauma which is often job related: repeated forceful grasping or pinching of tools, repetitive movements of hand or wrist, use of vibrating hand tools, awkward positions of hand or wrist like in case of computer users.
• Obesity
• Local injury to the wrist.
• Pregnancy may induce carpal tunnel syndrome and in many cases it may resolve after delivery of the baby. It is mostly due to hormonal changes in pregnancy.
• Tuberculosis affecting the joints may cause carpal tunnel syndrome.
• Bleeding in to the ligament of the wrist joint.

What are the symptoms of carpal tunnel syndrome?
The patient with carpal tunnel syndrome usually awakens in the night with pain and numbness in the hand and thinks that he does not have blood circulation in that hand. He often shakes the hand, rubs or uses hot and cold water to massage it. Some times the pain may go up to the shoulder. Day time activities like driving a car, holding the telephone receiver, reading a book or news paper may bring the typical symptoms. There will be pain and numbness over the medial side of the hand (thumb, index, middle and part of ring finger). When time goes, the patient will have weakness and clumsiness of hand. He will find difficult to hold a pen or button his shirt. He won't be able to feel the touch sensation in the hand.

How do you diagnose carpal tunnel syndrome?
Carpal tunnel syndrome is diagnosed by proper clinical examination by the physician and taking proper history from the patient. Usually the symptoms will be typical of carpal tunnel syndrome. Nerve conduction velocities can be tested. This test will tell how fast a signal travels in the nerve and it can be compared with the normal readings. Normally the sensory conduction study latency for median nerve is less than 3.7 milliseconds and in case of carpal tunnel syndrome it is greater than 5 milliseconds or some times not recordable.

Blood for testing for thyroid hormone levels, diabetes and anemia should be taken. Conditions like multiple myeloma and renal diseases should be rule out.

What are the treatment options available for carpal tunnel syndrome?
Carpal tunnel syndrome can be treated both by non surgical and surgical means. If there is any predisposing cause like diabetes, hypothyroidism or renal disorder, it should be corrected first. Splints should be given to the wrist for 2-4 weeks in order to give rest to the hand. Only 50% of the patients will improve with splints. Recurrence is again a common problem with non surgical management. Steroid injections may be of limited use.

Many surgical techniques are available. The aim is to cut the transverse carpal ligament in the wrist which is compressing the median nerve. Nowadays minimally invasive surgery using endoscopic techniques are used to treat carpal tunnel syndrome.

Did you know?
Carpal tunnel syndrome is the most common type of entrapment neuropathy in the upper limb. Entrapment neuropathy is a kind of nerve injury which results from repeated compression of a nerve by any external cause or due to anatomical factors in the body (like compression from bony structures, ligaments etc) .This causes pain , numbness and weakness of the affected hand.