Carpal tunnel syndrome is a compression of the median nerve at the wrist in the carpal tunnel. This causes pain, numbness, a dull ache in the hand or arm, lack of mobility of the hand, loss of grip and strength as well as other sensations such as; tickling, tingling, burning, and/or pricking. These sensations when related to CTS are a direct result of the compression of the median nerve due to various reasons to be discussed further.
Symptoms of Carpal Tunnel Syndrome
The main symptom and most common type of pain experienced with carpal tunnel syndrome is an intermittent numbness of the thumb, index finger, middle finger and lateral side of the ring finger. The pain generated from this numbness can often be so intense that it wakes the sufferer from sleeping. This numbness often occurs at night time, possibly because the wrists are often held flexed during sleeping hours, making sleeping somewhat difficult for those who suffer from this condition. Wearing a wrist splint at night to prevent flexion can help to relieve this problem.
Carpal tunnel syndrome if left untreated can lead to permanent nerve damage. This will more than likely result in constant numbness, muscular atrophy of some of the muscles on the palm of the hand at the base of the thumb (thenar eminence), and a weakness in the flexor-abduction of the hand.
Diagnosis of Carpal Tunnel Syndrome
The diagnosis of carpal tunnel syndrome is an observation of a combination of symptoms, clinical findings and possible electrophysiological testing by hand surgeons. The level of numbness in the wrist and fingers, night-time symptoms, muscle weakness of the palm, positive Tinel’s sign at the carpal tunnel, and abnormal sensory testing such as two-point discrimination are all taken into account by the doctor or surgeon before coming to a diagnosis for carpal tunnel syndrome. It is believed that a predominance of numbness rather than pain suggests the likely-hood of CTS as opposed to vice versa.
Causes of Carpal Tunnel Syndrome
The true cause of carpal tunnel syndrome is not entirely clear but considered to be a combination of genetic and environmental factors. Any condition that causes pressure on the median nerve at the wrist is generally considered to be an influence to the development of carpal tunnel syndrome. Some common conditions that may lead to CTS include obesity, oral contraceptives, pregnancy, hypothyroidism, arthritis, diabetes, and traumatic injury. Other causes of CTS include; benign tumors such as lipomas (a mass of adipose tissue or body fat), ganglions, (a mass of nerve cell bodies), and vascular malformations (blood vessel abnormalities) at the site of the median nerve at the wrist.
It is also believed that heavy manual work or work that involves vibrating tools such as electric sanders and other power tools of a similar nature may also contribute to this condition.
Carpal tunnel syndrome tends to be a progressive condition that develops over a period of time, unless it has occurred as the result of a traumatic injury.
Possible influential causes that reduce the carpal tunnel size to cause CTS
- Rheumatoid arthritis is a chronic disease of the joints that causes stiffness, swelling, weakness, loss of mobility, and leads to damage and eventual destruction of the joints. This can cause inflammation of the tissues and joints of the wrist thereby reducing the size of the carpel tunnel.
- Hypothyroidism is a deficiency in the production of thyroid hormones, or the slowing of the metabolic rate that is a result. A severe deficiency can cause sluggishness and weight gain can cause deposition of Mucopolysaccharides (long chains of sugar molecules) within the perineurium (a sheath of connective tissue enclosing a bundle of nerve fibers) of the median nerve, as well as the tendons passing through the carpal tunnel.
- During pregnancy some women can experience temporary CTS due to hormonal changes (high progesterone levels) and water retention which can cause a swelling of the synovial membrane (the soft tissue found between the joint capsule and the joint cavity of synovial joints). This can increase pressure to the median nerve.
- Previous injury to the wrist such as a fracture can cause a local long-term decrease in the size of the carpal tunnel.
- Medical conditions that lead to oedema (fluid retention) or are associated with inflammation such as; inflammatory arthritis, Colles’ fracture (a fracture of the radius bone in which a piece broken off at the end is shifted towards the back of the wrist. This type of fracture is commonly caused by falling on the palm of the hand. Amyloidosis (the accumulation of a protein-based substance ‘amyloid’ in the body’s organs and tissues), hypothyroidism, diabetes mellitus (a disorder in which there is no control of blood sugar, through inadequate insulin production), acromegaly and use of corticosteroids and oestrogens.
- Acromegaly is the overproduction of growth hormones, resulting in enlarged bones in the hands, feet, jaw, nose, and ribs of adults. This can cause the soft tissues and bones around the carpel tunnel to grow and increase pressure to the median nerve to cause CTS.
- Ganglions and Lipomas are benign tumors that can develop towards the inside of the carpal tunnel and reduce the amount of space inside. This condition is extremely rare and has less than a 1% chance of occurring.
- Obesity can also increase the risk of CTS due to fluid retention and swollen joints. Individuals who are classified as obese are said to be 2.5 times more likely to suffer from CTS.
- In certain individuals carpal tunnel syndrome can be influenced and aggravated by various activities of the hand and wrist, in particular, activities of a forceful and repetitive nature.
Conservative treatments include use of night splints and corticosteroid injection. The only scientifically established disease modifying treatment is surgery to cut the transverse carpal ligament.
Electro-diagnostic testing can verify the median nerve’s dysfunction.
- Phalen’s manoeuvre is a test that gently flexes the wrist acutely as far as possible for up to one minute and waiting for any symptoms or sensations to arise while holding this position. If numbness is felt along the pathway of the median nerve, the test is considered positive. The more quickly that any numbness, tingling, pricking, or a burning sensation (paraesthesia) begins, the more advanced the condition is said to be.
- Tinel’s sign test is a method for detecting aggravated nerves. Tinel’s sign test consists of lightly tapping the skin over the location of the flexor retinaculum (transverse carpal ligament, or anterior annular ligament) to encourage any ingling feelings (paresthesia) along the path and distribution of the median nerve.
- Durkan test, (carpal compression test), consists of applying a firm pressure to the palm over the nerve for up to 30 seconds to encourage symptoms has also been proposed.
Anatomy of the Carpal Tunnel
The carpal tunnel is situated at the base of the palm. The flexor retinaculum (transverse carpal ligament or anterior annular ligament) is a strong, fibrous band of ligamentous tissue. It is attached to the pisiform and hamate bones of the wrist on the medial (little finger side), and to the scaphoid and trapezium bones of the wrist on the lateral (thumb side). It lies over the carpal bones and transforms the deep groove on the front of the carpal bones into a tunnel, hence its name, the carpal tunnel. The median nerve and nine Flexor tendons of the digits pass through this tunnel.
The median nerve provides feeling and sensation to the thumb, index finger, long finger, and half of the ring finger. At the wrist, the median nerve supplies the muscles at the base of the thumb that allow it to abduct, or move away from the fingers and away from the palm. Compression of the median nerve as it runs deep to the transverse carpal ligament (TCL) causes weakness of the thenar eminence muscle, weakness of the flexor pollicis brevis muscle, opponens pollicis muscle, and abductor pollicis brevis muscle, as well as loss of sensation in the digits that are supplied by the median nerve.
There is no real evidence, only probability that the risk of contracting carpal tunnel syndrome is somewhat reduced if the suggestions below are exercised. Many people have suffered from CTS that do not have an occupation or activity that places extra stress on the wrist and hand. Contrary to this, are those many people who do not and will not suffer from CTS, and who do, have extremely active lifestyles that one would think may cause carpal tunnel syndrome.
The main suggested measure of prevention is to avoid repetitive stress to the hand and wrist by modifying your work activities. Take proper breaks if using the computer a lot. Use an alternative method for the keyboard such as; speech recognition (standard in windows 7). Taking turmeric for its anti-inflammatory properties, as well as omega-3 fatty acids, and B vitamins has been considered to help prevent carpal tunnel syndrome. None of this has been proven though, but that does not mean it does not help to reduce the risks of contracting CTS.
- The main treatments for CTS are; steroids in the form of tablets or by way of a local injection.
- The use of a splint to support the wrist and to reduce movement.
- The release of the transverse carpal ligament by surgery.
- Physiotherapy and alternative treatments such as acupuncture, ultrasound, nerve gliding exercises, carpal bone mobilization, magnetic therapy, laser and yoga.
Corticosteroid injections are often used and are generally very effective for the temporary relief of CTS symptoms. This is often the course of action taken while a person develops a long-term decision about possible surgery or is awaiting an available appointment. Corticosteroid injections are not the long-term treatment for CTS however, and are administered only until other long-term treatment options have been implemented or the symptoms have diminished considerably or completely.
Wrist braces and splints can be very helpful to support the wrist and inhibit hand movement that courses discomfort and pain by keeping the wrist straight. Wrist splints are particularly helpful during night time hours when the patient is asleep and unaware of the position of the arm and hand.
For most people suffering from chronic and severe CTS, surgery tends to be the only real long-term option that will provide permanent relief from carpal tunnel syndrome and its symptoms. Surgery for carpal tunnel syndrome is called “carpal tunnel release”. It is indicated when there is clinical evidence of compression of the median nerve. CTS surgery involves the release of the flexor retinaculum (transverse carpal ligament or anterior annular ligament). The ligament is cut which results in a release of pressure on the median nerve. It is extremely rare for CTS to re-occur after successful surgery.
Physiotherapy and alternative treatments can be beneficial and often help a lot, but it all depends upon the severity of the condition, the underlying cause of the CTS, and age of the patient, as to how well the carpal tunnel syndrome responds to any form of physiotherapy or alternative method of treatment.
Generally, the prognosis is good as the success rate of surgery for CTS is high. Most people are permanently relieved of the symptoms of their carpal tunnel syndrome with minimal nerve damage and hence numbness or tingling etc. Some cases of long-term chronic carpal tunnel syndrome as seen in the elderly can result in permanent nerve damage and permanent numbness, tingling, muscular atrophy, and weakness etc. Generally speaking though, the prognosis of CTS is a positive one.