What is Carpal Tunnel Syndrome?
The carpal tunnel syndrome is caused by compression of the median nerve in the wrist where it passes through the carpal tunnel. The carpal tunnel is located at the base of the palm of the hand. It is bounded on three sides by the carpal bones and on the palmar side by the fibrous flexor retinaculum or transverse carpal ligament. Nine flexor tendons traverse the carpal tunnel, along with the median nerve.The median nerve carries signals from the brain to control the actions of the fingers and hand.
It also carries information about temperature, pain and touch from the hand to the brain, and controls the sweating of the hand. Repetitive flexing and extension of the wrist may cause a thickening of the protective sheaths which surround each of the tendons. The swollen tendon sheaths, or tenosynovitis, apply increased pressure on the median nerve and produce carpal tunnel syndrome. Such injury results in sensations of numbness, tingling, pain, and clumsiness of the hand: these are the symptoms of called carpal tunnel syndrome.
What are the symptoms of carpal tunnel syndrome?
In the initial phases, the carpal tunnel syndrome is characterised by tingling or numbness of the hand, mainly in the first three fingers and part of the ring finger , especially in the morning and/or at night; this is followed by pain radiating to the forearm (symptoms defined as irritative). A person with carpal tunnel syndrome may wake up feeling the need to "shake out" the hand or wrist. If the condition worsens, there is loss of sensation in the fingers, with weakening of grip and thenar muscle atrophy (deficit symptoms). Many patients with carpal tunnel syndrome are unable to differentiate hot from cold by touch, and experience an apparent loss of strength in their fingers.Early neurological findings are reversible and symptoms intermittent, then it is possible segmental demyelination, axonal inijury ensues, and nerve dysfunction may be irreversible. The natural history of carpal tunnel syndrome is variable.
Who is at risk of developing carpal tunnel syndrome?
The carpal tunnel syndrome is very frequent. Symptoms consistent with carpal tunnel syndrome occur in up 15% of the population. The prevalence of electrophysiologically confirmed sumptomatic carpal tunnel syndrome is about 3% among women and 2% among men. The incidence of carpal tunnel syndrome is three times higher in women, perhaps because the carpal tunnel itself may be smaller in women than in men, and varies according to the work activities (up to 60 cases for every 100 workers in a particular job): in about 70% of the cases, it is bilateral and is prevalent in the dominant hand. Carpal tunnel syndrome usually occurs in adults. Carpal tunnel syndrome is three times more common among assemblers than among data-entry personnel.What are the causes of carpal tunnel syndrome?
Carpal tunnel syndrome is often the result of a combination of factors that increase pressure on the median nerve and tendons in the carpal tunnel, this increased pressure produces ischemia of the median nerve. Most likely the disorder is due to a congenital predisposition , (the carpal tunnel is smaller in some people than in others). Other contributing factors include trauma or injury to the wrist such as sprain or fracture. A lot of conditions may be associated with carpal tunnel syndrome: pregnancy, arthritis, amyloidosis, hypothyroidism, diabetes mellitus, acromegaly, therapy with estrogens and corticosteroids, tumours of tendon sheaths ,wrist cysts, menopause. Carpal tunnel syndrome is also associated with repetitive activities of the hand and wrist, awkward hand positions ,strong gripping , mechanical stress on the palm ,vibration . High incidence of carpal tunnel syndrome is present in food processing, manufacturing, logging, and construction work, cashiers, hairdressers, or knitters or sewers: those are examples of people whose work-related tasks involve the repetitive wrist movements associated with carpal tunnel syndrome. Bakers who flex or extend the wrist while kneading dough, and people who flex the fingers and wrist in tasks such as milking cows, using a spray paint gun, and hand-weeding are other examples. Research conducted by the National Institute for Occupational Safety and Health (NIOSH) indicates that job tasks involving highly repetitive manual acts, or necessitating wrist bending or other stressful wrist postures, are connected with incidents of carpal tunnel syndrome or related problems. The use of vibrating tools also may contribute to carpal tunnel syndrome.How is carpal tunnel syndrome diagnosed?
Early diagnosis and treatment are important to avoid permanent damage to the median nerve. A physical examination of the hands, arms, shoulders, and neck can help determine if the patient's complaints are related to daily activities or to an underlying disorder, and can rule out other painful conditions that mimic carpal tunnel syndrome. The differential diagnosis of pathologies of the hand and wrist includes entrapments of the nerve, carpal tunnel syndrome,Guyons'syndrome, cervical radiculopathy, tendon disorders, etc. Physicians can use specific tests to try to produce the symptoms of carpal tunnel syndrome. Loss of two- point discrimination in the median nerve distribution has low sensitivity and high specificity, tests of the patient's ability to perceive degrees of vibratory stimulation and direct pressure on the pulp of the finger in the median nerve distribution are technically demanding and have moderate sensitivity and specificity. In the Tinel test the physician taps the median nerve at the wrist. A tingling response in one or more fingers can toindicate damage to the median nerve. In the Phalen, or wrist-flexion, the patient puts the backs of the hands together and bends the wrists for one minute. Tingling of the fingers can to indicate damage to the median nerve. The presence of carpal tunnel syndrome is suggested if one or more symptoms, such as tingling or increasing numbness, is felt in the fingers within 1 minute. Phalen's test report a range of values for sensitivity and specificity, from 40 to 80 percent. The sensitivity of tinel's sign ranges from 25 to 60 percent, specificity from 67 to 87 percent. The history and physical examination have poor predictive value when the likelihood of carpal tunnel syndrome is low, they are most useful when there is a reasonable clinical suspicion of carpal tunnel syndrome.Electrodiagnostic examinations (nerve conduction studies and electromyography) and knowledge of the location and type of symptoms permits the most accurate diagnosis of carpal tunnel syndrome.
Both symptoms and electrodiagnostic studies must be interpreted carefully.
Electrodiagnostic studies are most useful for confirm the diagnosis in suspected cases and ruling out neuropathy and other nerve entrapments.
In a nerve conduction study, electrodes are placed on the hand and wrist. Small electric shocks are applied and the speed with which nerves transmit impulses is measured. In electromyography, a fine needle is inserted into a muscle; electrical activity viewed on a screen can determine the severity of damage to the median nerve. Ultrasound imaging and magnetic resonance imaging (MRI) can show the anatomy of the wrist but to date has not been especially useful in diagnosing carpal tunnel syndrome.
How can carpal tunnel syndrome be prevented?
Workers can do on the job conditioning, take frequent rest breaks, wear splints to keep wrists straight, and use correct posture and wrist position. Proper work station design reduces awkward wrist positions and minimizes the stressful effects of repetitive motions. NIOSH recommendations for controlling carpal tunnel syndrome have focused on ways to relieve awkward wrist positions and repetitive hand movements, and to reduce vibration from hand tools. NIOSH recommends redesigning tools or tool handles to enable the user's wrist to maintain a more natural position during work. Jobs can be rotated among workers. Employers can develop programs in ergonomics, the process of adapting workplace conditions and job demands to the capabilities of workers. However, research has not conclusively shown that these workplace changes prevent the occurrence of carpal tunnel syndrome.How is carpal tunnel syndrome treated?
Treatments for carpal tunnel syndrome should begin as early as possible, under a doctor's direction. The "Clinical Guideline on Wrist Pain" from the American Academy of orthopedic Surgeons and American College of Occupational Environmental Medicine recommends that patient with carpal tunnel syndrome modify his activities for two to six weeks while he is treated with wrist splint and nonsteroidal antiiflammatory medication. If these therapies are ineffective, or if patient has thenar muscle atrophy or weakness recommend referral to a specialist for injection or surgery. If carpal tunnel syndrome seems likely, conservative management with splinting should be initiated and patients should reduce activities at home and work. Where this is possible, patients should wear the splint during work . Important, for this aim, is the new wrist brace Policarpal. It is the latest generation product as it acts on the main cause of the problem. In fact, although it allows normal use of the hand (including thumb) and can be easily used during the day or at night, it effectively limits the bending-extension of the wrist (main cause of the problem). It can also be used by pregnant women. The hand can be used freely. If the condition fails to improve, the clinician should discuss the options of corticosteroidal injection and surgical therapy. Injection is effective if there is no loss of sensibility or thenar muscle atrophy and weakness and if symptoms are intermittent. More than 80 percent of patients with carpal tunnel syndrome report that a wrist splint alleviates symptoms. Splinting also reduces sensory latency, and so perhaps may alter the cause of carpal tunnel syndrome. Splint are more effective if maintain the wrist in neutral position. Nonsteroidal antiiflammatory medications, diuretics, and pyridoxina (vitamin B6) have been studied in small trials, with no evidence of efficacy. The prednisolone (20 mg daily for two weeks, followed by 10 mg daily for two weeks) makes a reduction in symptoms, but in the few studied patients were not followed after the four weeks. Patients who remain symptomatic after modification of activities and splinting can make injection of corticosteroids into the carpal tunnel. Symptoms generally recur within one year. The risks of injection and nerve damage resulting from injection are considered low but have not been formally studied. The optimal number of injection per year has not been studied. Acupuncture for carpal tunnel syndrome has not been evaluated in controlled studies. If a patient has symptoms and signs for an axonal loss - costant numbness, loss of sensibility and thenar muscolar atrophy or weakness - surgery should be seriously considered. Surgery is done under local anesthesia and does not require an overnight hospital stay. Many patients require surgery on both hands. The operation consists in cutting the ligament through the carpal (roof of carpal tunnel). This can be done using the traditional technique or by endoscopy. The operation must not be left until it is too late as there is risk of permanent damage. More than 70 percent of patients report being completely satisfied or very satisfied with carpal-tunnel surgery (tradional or endoscopic); 70 to 90 percent of patients report being free of nocturnal pain after surgery. There have been no randomized controlled trials comparing carpal tunnel release with conservative therapy. Although symptoms may be relieved immediately after surgery, full recovery from carpal tunnel surgery can take months. The majority of patients recover completely. Some patients may have infection, nerve damage, stiffness, and pain at the scar. Occasionally the wrist loses strength because the carpal ligament is cut.By a specialist Neurophysiopathologist
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