Radial nerve syndrome | Radial nerve

Radial nerve syndrome

A compression syndrome of a peripheral nerve like the radial nerve is caused by chronic pressure damage. For each nerve, there are anatomically particularly vulnerable areas where the nerve is easily damaged. When the radial nerve is damaged, sensitivity is impaired in its innervated region, i.e. the area of the skin that is supplied by the radial nerve.

For example, the back of the thumb and index finger of the hand may feel numb, formication or pain. These symptoms are also possible on the ventral side of the forearm, i.e. the side that merges into the palm of the hand. Especially the transition to the thumb (radial forearm) is affected.

Since the radial nerve primarily supplies the extensor muscles of the upper extremity (brachial triceps, brachioradialis, supinator, hand and finger extensors), a loss of the radial nerve results in a so-called drop hand. Due to the failure of the extensors, the hand and the fingers hang limply in the wrist. Depending on the exact height of the lesion of the nerve, some of the described failure symptoms apply and others do not.

The doctor can use this to diagnose the exact location of the nerve damage. He distinguishes between a proximal and a distal lesion (e.g. in a fracture of the humerus), as well as supinatorlogenous syndrome and lesions of the purely sensitive ramus superficialis. Wartenberg compression syndrome is a compression injury of the sensitive branch of the radial nerve.

Here, sensory disturbances occur without any muscle weakness occurring. The causes can be wristwatches that are too tight, plaster casts or handcuffs. The sensory disturbances (numbness, tingling or pain are possible here) are located on the back of the thumb and index finger, and the skin between the two fingers is also affected.

Incarceration of the radial nerve

Nerves react extremely sensitively when they are pinched. Especially in the upper extremity, many important nerves run in a relatively small space. At certain points, the risk of the nerve becoming trapped between muscles, tendons, soft tissue and bony structures is particularly high.

The radial nerve is a mixed sensitive and motor nerve, which means that it is responsible for feeling (sensitivity) and voluntary muscle contractions (movements) in certain areas of the arm and hand. It is important to note that only the part of the arm or hand that is located far from the damaged area is affected by functional deficits. If there is damage to the nerve in the area of the wrist, this can lead to loss of sensation and muscle weakness in the area of the hand and fingers, but never to loss of function in the area of the upper arm or forearm.

Common causes of radial nerve entrapment are accidents or pressure lesions, as well as slowly developing bottlenecks due to an increase in muscle mass or soft tissue. The radial nerve can also be constricted by medical treatment (e.g. positioning during operations, plaster casts or injections).