Summary
When the carpal tunnel, a small passage in the front of the wrist, is narrowed, the median nerve passing through it is compressed, resulting in abnormal symptoms in the area dominated by the median nerve.
Definition
The carpal tunnel is a small passage formed by the bones and ligaments that make up the wrist under the skin tissue on the front of the wrist, through which nine tendons and one nerve pass. In carpal tunnel syndrome, when this passage is narrowed for various reasons or internal pressure increases, the median nerve that passes here is damaged, resulting in abnormal symptoms in the palm and fingers, which are the innervated areas of this nerve. It is known that there is a greater than 50% chance of having this disease in one’s lifetime, and it is the most common neurological disease in the arm.
Cause
Theoretically, any case that can reduce the cross section of the carpal tunnel can be the cause, but in most cases, the exact cause is not found. The most common cause is the thickening of the ligament covering the carpal tunnel, which compresses the median nerve. In cases where the cause is relatively well known, there are fractures or dislocations around the carpal joint and their sequelae, swelling or aponeurosis due to infection, inflammatory disease or trauma, and compression due to tumors in the carpal tunnel.
Symptoms may appear as the median nerve is compressed due to narrowing of the carpal tunnel due to fractures and dislocations of the wrist, and there are no symptoms at first due to sequelae such as incorrect attachment (malunion) or non-adherence (nonunion) of these fractures, but over time There may also be cases of delayed onset of symptoms. Infection or a disorder that causes synovitis, such as rheumatoid arthritis or gout, the synovial membrane of the flexor tendon may swell (swell) or grow in the carpal tunnel and press on the median nerve. In some cases, such as generalized amyloidosis, certain proteins may be deposited in the ligaments of the wrist.
It occurs more commonly in women, the obese, the elderly, and people with diabetes. This syndrome may appear temporarily only during pregnancy, and although it occurs in both men and women, it most often occurs between the ages of 40 and 60, and is more common in women after middle age. It is also common in patients undergoing dialysis for chronic renal failure.
Symptoms
The characteristic symptom is pain in the wrist, along with numbness in the thumb, index and middle finger, and palm area, which are the areas governed by the median nerve, that intensify at night. Having these triggers makes carpal tunnel syndrome more likely. Occasionally, if the pressure on the median nerve is severe, weakness and atrophy of the thumb muscle may appear beyond numbness and decreased sensation.
Symptoms can be divided into pain, paresthesia, and movement disorders. Complains of tingling and burning pain in the thumb, index finger, middle finger, and palm, as well as numbness and abnormal sensations in the hand. The nature of pain and dysesthesia is uncertain and sometimes vague. Bending the wrist for 1 to 2 minutes may cause tingling in the area, and tapping the wrist may cause the same symptoms. In severe cases, you may feel burning pain in your hand even while you are sleeping, and after waking up, if you continue to move your hand and wrist, such as flicking your wrist, the pain may subside (night crying).
As the disease progresses to a certain extent, the thumb side loses sensation, weakness (weakness) and atrophy of the thumb muscle may appear, and motor paralysis symptoms such as weakness in the hand and poor use of the wrist may occur. Complaints of swelling in the fingers and palms, but usually not actually swollen. When you put your hands in cold water or the weather is cold, your fingertips are exceptionally cold and numb symptoms are also commonly observed.
Diagnosis
It is necessary to see a specialist because it is necessary to differentiate between several diseases that complain of similar symptoms. During treatment, the location and degree of sensory abnormalities are identified, and the degree of motor function weakness is also checked. Decreased motor function is mainly caused by muscle weakness or paralysis in the thick part of the palm of your hand (the thumb). You can check the degree of muscle weakness by placing your thumb and little finger (pinky finger) face to face and pressing the thumb ball while applying force.
At this time, the normal thumb muscles are strongly contracted to get the feeling of pressing a ping-pong ball, but in the case of patients with carpal tunnel syndrome, the muscles cannot contract properly and become soft. If the atrophy of the thumb muscles is severe, this area is not thick and hollow, which means that the median nerve is compressed considerably, and it can be an indicator that complete recovery after surgery is difficult. Tests used include nerve percussion, carpal flexion, and electrical tests.
Nerve percussion is a test in which abnormal sensations or pain are induced in the area innervated by the median nerve when the nerve in the wrist through which the median nerve passes is pressed with a finger.
In the carpal flexion test, when the wrist is severely bent for about 1 minute with the palm facing inward, pain and abnormal sensations appear or increase in the area innervated by the median nerve. In this test, when the cross-sectional area of the carpal tunnel is reduced by bending the wrist forward, the compression of the nerve becomes severe and causes pain.
Plain radiographs are usually done to rule out the cause and many other disorders.
An electrical test can confirm EMG abnormalities in the thumb muscles and delay in nerve conduction velocity in the wrist. However, electrical tests may be normal in the initial mild case of nerve compression and release, even if the patient’s symptoms are severe.
Treatment
The principle of treatment is to find and remove the local cause of compression of the median nerve, but unfortunately in most cases the cause is not identified.
Treatment can be broadly divided into non-surgical treatment and surgical treatment.
1) Non-surgical treatment
Non-surgical treatment can be tried in the early stage when the cause of the disease is not clear, there is no atrophy of the muscles of the thumb (the thick part from the palm to the thumb), and other symptoms are relatively mild. Prohibition of excessive use of the wrist, fixation of a splint on the wrist, drug treatment using anti-inflammatory drugs, and steroid injection into the carpal tunnel are possible.
If pain during sleep is the main symptom, an easy-to-remove splint to keep the wrist in a neutral position may improve symptoms. If you have mild pain even when you are awake, and if you are diagnosed with ‘synovitis of the flexor tendon not caused by infection’, drug treatment such as anti-inflammatory drugs can be effective.
Steroid injection into the carpal tunnel causes atrophy of the soft tissue, and temporary or permanent improvement in symptoms can be expected. However, in many cases, symptom relief is temporary and the recurrence rate is high. Therefore, it can be performed on a limited basis only when the cause of the disease is not known. When the pain is relatively severe but there is no or slight electrical abnormality, or when the cause naturally resolves after a certain period of time, such as pregnancy, it is effective. Can be used.
2) Surgical treatment
The most effective treatment for carpal tunnel syndrome is surgical widening of the carpal tunnel. The target of surgical treatment is when a definite pathology to be removed, such as a tumor, is found, when atrophy of the thumb is clear, when the degree of nerve damage is severe in an electrical test, or even if the symptoms are not severe, non-surgical treatment for 3 to 6 months It is performed when there is no improvement or when it worsens. Non-surgical treatment is often unsatisfactory in long-term results, whereas surgical treatment is relatively simple and has good results, so there is a tendency to prefer early surgical treatment rather than long-term non-surgical treatment.
Surgical treatment is basically to widen the carpal tunnel by cutting the transverse carpal ligament, which is called carpal tunnel release, and can be divided into open and arthroscopic methods depending on how the skin is incised. Once surgical treatment is to be performed, a preoperative diagnosis is made clearly and the type of surgery to be performed is decided after accurately examining the patient’s condition, such as the risk of anesthesia. If the cause is clear, surgery to remove the cause should be performed at the time of carpal tunnel release.
Open carpal tunnel release is a relatively simple procedure that can be performed with a 2-3 cm incision under local anesthesia. Arthroscopic carpal tunnel release has the advantage of reducing the pain felt by the patient after surgery due to the reduced skin incision, but has the disadvantage of requiring the use of expensive equipment and the possibility of damage to nerve branches. With the recent development of open carpal tunnel release, the frequency of arthroscopic release is gradually decreasing.
3) Treatment results
When free surgery is performed as a surgical treatment, the operated hand can be used at a minimum after about 2 to 3 days, and the hand can be used in daily life to some extent in about 2 weeks. However, in some cases it may take about 6 months or longer to achieve maximum functionality. The symptoms of waking up from pain during sleep and the feeling of tightness in the wrist disappear immediately after surgery, and abnormal sensations accompanied by pain usually improve within about a week. However, although there are cases where the recovery of sensation or the strength of the thumb and thumb improves immediately, it usually takes several months.
In particular, in cases where atrophy of the thumb bulb has progressed for more than several years, some degree of recovery is achieved in most cases, but there is a possibility that it may not be permanently recovered. For about 3 to 6 months, they complain that their palms feel tingling and tight, and some discomfort or pain may occur when the wound is pressed, but in most cases it improves, and the duration varies from patient to patient.
Prognosis/Complications
How long after the onset of symptoms and how much deterioration has progressed varies from patient to patient and cannot be accurately determined. Usually, the symptoms naturally improve if you do not work and take enough rest, but the symptoms are initially weak, so patients often tolerate it, so atrophy of the thumb muscles progresses considerably, resulting in motor function disorders, making it difficult to use the hands. Many people come to the hospital only after feeling uncomfortable. If median nerve compression continues in the carpal tunnel, nerve damage progresses slowly, and the symptoms of this syndrome persist and become severe.
However, if the nerve compression continues, the patient may mistakenly feel that the symptoms have improved because the symptoms of waking up with pain during sleep disappear and the pain also decreases. In this case, the nerve damage becomes more severe, leading to numbness in the affected area, severe atrophy of the thumb muscles, and a marked decrease in hand function. If the damage to the median nerve is so severe that muscle weakness (weakness) and even atrophy appear, it may not respond to general symptomatic treatment.
In the case of surgery, the result is generally good, and serious complications are rare, within 1-2%. Possible complications include damage to the median nerve or its branches and flexor tendons, postoperative hemorrhage or hematoma formation, and some delayed healing due to infection.