I. Overview “mouse hand” is commonly and narrowly defined as “carpal tunnel syndrome”, refers to the human median nerve, as well as the blood vessels into the hand, at the carpal tunnel by the compression of the symptoms, will mainly lead to the finger and middle finger stiffness pain, numbness and thumb muscle weakness. In modern times, more and more people are exposed to and use computers for a long time every day. Most of these Internet users repeatedly type on the keyboard and move the mouse every day, and the wrist joints become paralyzed, swollen, painful, and spastic due to long-term intensive, repeated, and excessive activities, causing the wrist muscles or joints to become an increasingly common disease of modern civilization. Second, the etiology 1, local factors (1) factors that cause the carpal tunnel volume reduction such as Colles fracture, Smith fracture, navicular fracture and lunar dislocation after deformed healing, and limb hypertrophy. (2) Factors causing increased carpal tunnel contents such as lipoma, fibroma, tendon sheath cyst, abnormal muscle position in the carpal tunnel (superficial flexor muscle belly too low, earthworm muscle belly too high), non-specific synovitis, hematoma. 2, systemic factors (1) factors causing neurodegeneration such as diabetes, alcoholism, infection, gout, etc. (2) Factors that change the balance of body fluids such as pregnancy, oral contraceptives, long-term hemodialysis, and low thyroid function (3) Postural factors Those who work excessively with their wrists, such as computer operators, disabled people walking with crutches, repeated flexion and extension of fingers and wrist joints. However, it should be noted that the cause of carpal tunnel syndrome is not clear in some patients. Clinical manifestations The clinical manifestations of carpal tunnel syndrome are numbness, tingling or burning-like pain in the middle finger, middle finger and ring finger, which is aggravated at night after daytime labor, or even waking up from sleep; localized pain often radiates to the elbow and shoulder; poor thumb abduction muscle strength, and occasional sudden loss of hand when carrying things. Examination: pain increases when pressing or tapping the transverse carpal ligament and dorsal extension of the wrist joint; in cases with long duration of disease, there may be atrophy of the greater interphalangeal muscle. Numbness and pain in the wrist, palmar surface of the hand, thumb, index finger and middle finger, or accompanied by inflexible hand movements and weakness; pain symptoms are aggravated at night or early in the morning, and may radiate to the elbow and shoulder, and are alleviated by daytime activities and hand shaking; sensation in the above areas is diminished or disappears; or even hand muscle atrophy and paralysis occurs. If this occurs and is not relieved for several days in a row, experts suggest that one must go to a regular hospital to see a doctor as soon as possible in order to make an early diagnosis and take measures. Clinically, some patients may suffer from long-term lesions that lead to atrophy of the muscles under the thumb, and even intermittent skin whitening and cyanosis; in severe cases, cyanosis of the thumb and index finger, fingertip necrosis or atrophic ulcers may occur, becoming irreversible. Carpal tunnel syndrome occurs in the age of 30 to 50 years, and is five times more common in women than in men. The pain and sensory numbness of the thumb, index and middle finger are caused by compression of the median nerve, which is about 1/3 to 1/2 of the cases with bilateral onset and 9:1 female:male. Initially, it often manifests as sensory dysfunction of the finger end, often waking up with numbness or burning pain a few hours after sleep, and relieving after activity. In a small number of patients, neurotrophic disorders occur due to the long duration of the disease, with atrophy of the masseter muscle, intermittent skin whitening and cyanosis, and in severe cases, cyanosis of the thumb and index finger, finger tip necrosis or atrophic ulcers. On examination, the palmar aspect of the wrist may be tapped, causing numbness and pain in the median nerve innervation area, which is positive for Tinel’s sign. In some patients, abnormal finger sensation increases after 60 seconds of extreme flexion of the wrist joint, which is a positive Phalen test. The use of sphygmomanometer in the upper arm pressure to distal limb venous dilatation can induce the appearance of symptoms. The electrophysiological examination suggests that the electromyography of the interosseous muscle and the median nerve conduction velocity of the wrist and finger have nerve damage signs, which is of some significance for the diagnosis. (1) Nerve conduction velocity measurement The normal time interval from the proximal transverse carpal stripe to the thumb short adductor muscle is less than 5ms, while its nerve conduction time is prolonged in carpal tunnel syndrome. (2) Measurement of muscle potential The muscles innervated by the median nerve of the greater pisiformis can be seen to have denervation changes. 2.X-ray examination X-ray plain film can understand whether there are bone and joint pathological changes in the carpal bone area. 3.Arthroscopy Arthroscopy is a new examination method developed in recent years. Under the arthroscope, the pathological changes in the carpal tunnel can be understood, and the diagnosis can be further clarified. 4.CT and MRI examinations MRI and CT examinations of the wrist can provide useful clinical information and can be used to understand the situation in the carpal tunnel, but they are not used as routine examinations. V. Diagnosis When carpal tunnel syndrome is suspected, the following tests should be performed to clarify the diagnosis: 1. Tinel’s sign. Tapping the median nerve with the finger at the proximal edge of the carpal ligament, and radiating pain in the thumb, index and middle fingers is considered positive. 2. Wrist flexion test. Rest both elbows on the table, with the forearms perpendicular to the table, and both wrists naturally palmarly flexed. At this point, the median nerve is pressed against the proximal edge of the transverse carpal ligament, and pain soon appears in people with carpal tunnel syndrome. 3. Cortisone test. Inject hydrocortisone into the carpal tunnel, and if the pain is relieved, it will help to confirm the diagnosis. 4, Tourniquet test. Inflating the sphygmomanometer above the systolic pressure for 30 to 60 seconds that can induce finger pain is positive. 5.Wrist extension test. Maintain the wrist in the hyperextended position, and if the pain appears soon, it is positive. 6.Finger pressure test. Finger pressure at the median nerve pressure point at the proximal edge of the transverse carpal ligament is considered positive if it can induce finger pain. 7. Median nerve conduction velocity. The conduction velocity of the median nerve from the proximal transverse carpal ligament to the thumb to palmar muscle or thumb short extensor muscle is shorter than 5 microseconds when normal. If it is longer than 5 microseconds, it is abnormal. Carpal tunnel syndrome of up to 20 microseconds indicates damage to the median nerve. Surgical treatment should be considered for conduction times greater than 8 microseconds. VI. Differential diagnosis Many diseases can present with symptoms similar to carpal tunnel syndrome, such as numbness and pain in the fingers. Therefore, attention should be paid to differentiation to prevent misdiagnosis. 1. The main differential diagnosis should be distinguished from peripheral neuritis and neurogenic cervical spondylosis. Peripheral neuritis is dominated by numbness in the fingers, and pain is mild. Mostly both hands, symmetrical sensory impairment, the difficulty in differentiation is not great. 2. It is important to distinguish neurogenic cervical spondylosis from carpal tunnel syndrome. Both can have numbness and pain in the fingers, but the treatment is completely different. At the same time, the two may co-exist, that is, the same patient suffers from cervical spondylosis and carpal tunnel syndrome at the same time, so careful differentiation is needed to achieve good results by treating them separately. Neurogenic cervical spondylosis is characterized by radiating pain that radiates distally from the neck and shoulder. Patients have symptoms in the neck, shoulder, upper limbs and hands at the same time. There is a relationship between the pain and neck movement. Cervical spine X-ray and CT may show degenerative changes in the cervical spine and narrowing of the corresponding nerve root soles. Pain and sensory disturbances are widespread. Electromyography may provide a basis for differential diagnosis. Carpal tunnel syndrome presents with nocturnal finger pain, positive pressure finger test, and prolonged median nerve conduction velocity from the proximal transverse carpal stripe to the greater fissure on electromyography. 3. In addition, it must be differentiated from peripheral neuritis, diabetic peripheral neuritis, rheumatoid arthritis and rheumatoid arthritis, hypothyroidism, gout, etc. Coles fracture malunion, anterior lunate dislocation, soft tissue edema caused by infection or trauma, thickening of the transverse carpal ligament, tendon sheath cyst, lipoma, yellow tumor, some systemic diseases such as obesity, diabetes, thyroid dysfunction, amyloidosis or Reynaud’s disease can sometimes be combined with carpal tunnel syndrome. Carpal tunnel syndrome is sometimes combined. In the early stage of the lesion, it shows edema and congestion of the median nerve, gradually causing fibrosis within the nerve due to compressive ischemia, compression of the nerve axon and disappearance of the myelin sheath, and finally the nerve tissue turns into fibrous tissue, and its intra-neural tube disappears and is replaced by collagen tissue, which becomes irreversible. Treatment 1.Non-surgical treatment For early stage of the disease and mild symptoms, a small splint can be used to fix the wrist joint in a neutral position for 1 to 2 weeks, and most patients have results. In addition, corticosteroid closure treatment can be used in the carpal tunnel. Usually, trimethoprim (trimethoprim, chlortetracycline A) 0.5g plus 2% lidocaine 1ml is used for local closure once a week for 3-4 weeks. The method of closure is: in the distal transverse wrist immediately adjacent to the long palmar tendon (if the long palmar tendon is absent in the extension of the ring finger) ulnar side into the needle, the tip of the needle points to the middle finger, the needle and the skin at an angle of 30 °, slowly into the carpal tunnel about 2.5 cm. If it causes abnormal sensation, it is necessary to withdraw the needle to reposition. It has been investigated that after 3 times of closure, 81% of patients have remission, which lasts from 1 day to 40 months, but usually relapse after 2 to 4 months. If it is not effective after the first closure, it cannot be closed again. It has also been found that the effectiveness of local closure and surgical efficacy are closely related, and that good local closure results in good surgical treatment. It must be noted that if the patient suffers from rheumatoid arthritis, diabetes, hypothyroidism, the original disease must first be actively treated. 2.Surgical treatment For serious symptoms, conservative treatment for 2 months is ineffective, early surgery should be performed. Usually the transverse carpal ligament is incised and the carpal tunnel is decompressed. The surgical incision is usually made by a curved incision with the radial margin of the lesser trochanter convex to the ulnar side, and extended to the upper wrist, which can avoid damaging the palmar cutaneous branch of the median nerve. The long palmar tendon and the radial carpal flexor tendon are retracted to both sides to expose the median nerve and the transverse carpal ligament, and the transverse carpal ligament is incised along the ulnar side of the median nerve from near to far to avoid injury to the median nerve return branch, because the median nerve return branch crosses the transverse carpal ligament to the greater piriformis muscle in about 23% of people. After incision of the transverse carpal ligament, the carpal tunnel is probed and if the median nerve is adherent to the surrounding tendon bursa, it is carefully released, and if there is a new organism in the carpal tunnel, it is surgically removed. The transverse carpal ligament was incised without reconstruction, and the wound was sutured after complete hemostasis. After surgery, the short arm cast is fixed in the extended wrist position for 7 to 9 days to avoid herniation of the flexor tendon, and then the cast is removed to start active activities. It has been suggested that carpal tunnel dissection be followed by microscopic release of the median nerve bundle. However, intergroup separation of the nerve bundles can cause nerve fiber avulsion, extensive scar formation within or around the nerve after surgery, and reflex sympathetic dystrophy. It has also been found that there is no significant difference in the efficacy between simple carpal tunnel dissection and carpal tunnel dissection plus intraneural release, and therefore intraneural release is of little significance and is rarely used. Arthroscopic carpal tunnel decompression: This new technology has only been applied in recent years. The application of arthroscopic carpal tunnel decompression has the advantages of less surgical trauma, faster recovery of patients’ daily life and work, and shorter hospitalization time, which is welcomed by patients. However, arthroscopic carpal tunnel decompression has complications such as median nerve or superficial palmar arch severance, hematoma, and ulnar nerve irritation in the wrist, which should be avoided.