Radial Tunnel Syndrome

　　The radial tunnel syndrome is common in the dominant hand, and it is prone to occur in manual laborers and athletes who need to repeatedly rotate their forearms. Patients aged 40 to 60 are more common, with a similar male-to-female ratio. There is no obvious trauma history before onset, and symptoms appear gradually. These data support the

　　1. Trauma Spinner reported 10 cases of radial tunnel syndrome, of which 9 had a history of forearm injury. Forearm injury caused by trauma can form scar tissue and adhesions at the areas where the radial nerve is easily compressed, leading to the occurrence of nerve compression.

　　2. Tumor Cysts and lipomas in the rotator muscle sheath of the posterior interosseous canal.

　　3. Fracture and dislocation Radial head dislocation and Monteggia fracture are prone to cause radial nerve injury.

　　4. Rheumatoid arthritis The rheumatoid lesions can cause thickening of the synovium, and in the late stage, they can destroy the humeroradial joint capsule, causing radial head dislocation and nerve injury.

　　5. Local scar inflammation and trauma, local scars may gradually appear, which can lead to nerve compression.

　　6. Viral neuritis, if the symptoms occur for 3 months, most can be inquired about the history of 'common cold', and other related causes cannot be traced. After viral infection, it can also cause proliferation of nerve and perineural connective tissue.

　　7. Iatrogenic injury is mainly local injection of local anesthetic, local anesthetic drugs, traditional Chinese medicine, etc., which can lead to the formation of scar tissue around the nerve and nerve injury.

　　Tennis elbow is a typical complication of the radial tunnel syndrome. Housewives, bricklayers, carpenters, and others who repeatedly use their elbows for a long time are also prone to this disease. Studies have shown that the extensor muscles of the wrist, especially the radial short extensor muscle, have a very high tension when straightening the wrist and exerting force towards the radial side, which can easily cause excessive stretching of some fibers at the junction of muscle and bone, forming slight tears.

　　Another complication of the radial tunnel syndrome is the demyelination of nerve fibers, even the degeneration of distal axons, and the Wallerian transformation of the myelin sheath. During limb movement, nerve fibers in narrow channels may undergo chronic traumatic inflammation under mechanical stimulation, and exacerbate the vicious cycle of edema and ischemia.

　　The main clinical manifestation of the radial tunnel syndrome is pain. The pain is dull, located on the lateral side of the elbow, which can radiate proximally along the radial nerve or distally along the posterior interosseous nerve; upper limb movement can exacerbate the symptoms, and night pain is more obvious, and severe cases often wake up at night with pain; venous stasis, especially when applying a tourniquet, can also worsen the pain.

　　A few patients may also show muscle weakness, sensory dullness and numbness, and weakened extensor muscle strength of the fingers and thumb, which is often caused by pain. In the late stage, muscle atrophy may also occur.

　　The radial tunnel syndrome is closely related to modern living and working conditions and can be completely prevented. The methods of prevention are also very simple, that is, to avoid the long-term immobilization of the upper limbs in a mechanical and frequent movement state as much as possible. After working for a period of time, you should move your limbs, do some relaxing exercises, shift your attention, and do not maintain a long-term upper limb movement.

　　The clinical examination of the radial tunnel syndrome should first exclude radial head dislocation and Monteggia fracture with X-ray examination. The commonly used examination methods in clinical practice include the following 3 types:

　　1. Radial Tunnel Compression Test

　　A movable small bundle can be felt about 5cm from the lateral epicondyle of the humerus in some patients, which is the site where the interosseous posterior nerve passes through the Frohse arch. Light touching can cause tenderness. When examining, a comparison of both sides should be made.

　　2. Middle Finger Extension Test

　　Tighten the fascia of the radial side of the wrist short extensor muscle by extending the middle finger, compressing the interosseous posterior nerve. Examination method: when the elbow is in pronation position and the forearm is completely extended, have the patient extend the middle finger against resistance. Pain in the radial tunnel area is positive. Local anesthesia treatment can help in differential diagnosis.

　　3. X-ray Examination

　　Can exclude subluxation of the radial head and Monteggia fracture.

　　The diet of radial tunnel syndrome patients should be light, easy to digest, with more vegetables and fruits, a reasonable diet, and attention to adequate nutrition. In addition, patients should also pay attention to avoiding spicy, greasy, and cold foods.

　　Early conservative treatment can be performed for radial tunnel syndrome.

　　The methods of conservative treatment include: fixing the patient's forearm in the position of extension of the wrist, flexion of the elbow, and posterior rotation of the forearm to maximize the reduction of the tension in the radial tunnel, achieving the purpose of reducing nerve entrapment; local anesthesia, once a week, for 2 to 3 consecutive times as a course of treatment; at the same time, taking B vitamins and methimazole orally.

　　If conservative treatment is ineffective, surgical treatment can be performed.

　　For early-stage patients, if there is weakness or inability to extend the fingers, or refractory pain in the elbow, a decompression surgery can be performed; for late-stage patients, if there is significant atrophy of the extensor muscles, and the time exceeds one and a half years, consider performing a direct tenodesis procedure.

　　Surgical Methods: Surgery often adopts the Henry incision in front of the elbow, starting from the upper elbow joint and ending 7cm below the elbow joint. Find the radial nerve in the interval between the biceps brachii and brachioradialis muscles, trace it downwards to the supinator muscle sheath, where it can be seen that the radial recurrent artery has multiple branches forming a fan-shaped coverage over the deep branch of the radial nerve. Ligature the vessel, incise the Frohse arch and the supinator muscle sheath, and remove all factors that may compress the nerve. Then, under the microscope, carefully inspect the deep branch of the radial nerve, and if necessary, incise the epineurium to check each nerve fascicle. If nerve degeneration is obvious, it can be cut and reanastomosed. If necessary, consider performing a tenodesis procedure.