Neuropathy of the radial nerve: why it arises and how it manifests itself

Neuropathy of the radial nerve is a common pathology well known to neurologists, the main cause which is the compression of the nerve under the influence of various factors with the appearance of characteristic symptoms.

The pathological condition of the nerve or several nerves resulting from compression, trauma, infection or other causes and leading to functional disorders in the innervation of the nerve, ischemic processes and trophic disorders in the surrounding tissues is called neuropathy of the radial nerve.

The basis of the neuropathic process is the destruction of nerve structures due to eating disorders and exposure to toxic substances coming from the inflammation zone surrounding tissues, there is pain and swelling in the zone of innervation and there are sensitive, motor, vegetative and trophic disorders.

Why does it arise?

During sleep in an uncomfortable position, the radial nerve is squashed by surrounding tissues - neuropathy develops.

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Lesion of the radial nerve is more common among other nerves of the upper limb: the median or ulnar. The reason for this can serve as the following factors:

• Compression-clamping (compression) of the nerve: a) during sleep, when a person is long in an uncomfortable position on a hard surface, the hand is pressed down by the head or trunk, for example, during the phase deep sleep in alcoholic intoxication or severe fatigue; b) "crutch" paralysis, compression of the nerve with a crutch; c) cases of compression by a pacemaker; d) tumor of the axillary fossa.
• Trauma of the nerve as a result of a fracture of the humerus, dislocation of the shoulder or forearm;
• Iatrogenic factors are associated with a medical error: a) compression by a tourniquet when performing manipulations to stop bleeding when it is held for a long time on the arm; b) violation methods of conducting intramuscular or subcutaneous injections in the shoulder area, when there are features of the anatomical location of the nerve and a high risk of injury;
• Infectious nerve damage. Bacterial: with typhus, pneumonia, tuberculosis; Viral: measles, influenza, pneumonia, herpes;
• Intoxication (in rare cases) lead, arsenic.

A little anatomy

Before proceeding to the symptoms of the pathology of the radial nerve, let us recall its anatomical features. So, the radial nerve is peripheral, that is located outside the brain or spinal cord and is part of the brachial plexus. It is formed by the fibers of the root of the 5th and part of the 8th cervical and partly by the rootlet of the 1st thoracic spinal nerves, it descends downwards into the axilla (the first place of possible compression of the radial nerve as a result of external influence) from the brachial plexus in the form of its posterior secondary fascicle. Further the nerve descends downwards, along the humerus, passes in the so-called furrow of the radial nerve (bone spiral groove), tightly presses against it, skirting it in the form of a spiral, behind in its middle third (the second place of probable compression of the nerve).

In the region of the elbow joint capsule, the radial nerve gives off two branches, superficial and deep. The first passes along the outer surface of the forearm and passes to the dorsal (posterior) surface of the lower end of the forearm, divided into small branches that innervate the radial half of the rear of the hand from the nail phalanx of the 1st finger, the middle phalanx of the 2nd, and the radial side of the third finger.

The radial nerve contains motor and sensitive fibers, so it is called mixed. The motor portion of the fibers innervates the extensor muscles of the shoulder (triceps), wrists, fingers, supinator (performs the function of lead) of the forearm, a muscle that performs the removal of the thumb. The sensitive part of the nerve fibers of the radial nerve branches into the skin of the shoulder, the forearm from the dorsal (posterior) side, the rear of the hand and the first three fingers of the hand.

The defeat clinic

From the level of nerve damage will depend on the presence of certain clinical manifestations:

• motor;
• sensitive;
• trophic and vegetative.

1. If this is the area of ​​the axilla and shoulder in the middle third, then the following disorders occur: a) motor: decrease in strength (paresis) of muscles innervated by the data nerve, in this case, when the patient tries to raise his hands and stretch them in front of him, the hand with the pathological nerve will hang ("hanging brush"). It is impossible to remove the first finger from the second, to unbend the forearm and the wrist due to damage to the extensor muscles. The third finger is superimposed on the adjacent finger. Supination (turning outward) of the forearm with extension of the hand is difficult. There is no ulnar (extensor) reflex (when the neurological hammer strikes the foreleg outward from the outside of the elbow joint, the forearm is unbent), and the carporadial (tapping with a hammer in the wrist area of ​​the styloid process of the radial bone leads to flexion of the forearm at the elbow joint and phalanges of the fingers. b) Sensitive: burning pain and tingling sensation, numbness in the fingers and forearm, hypoesthesia (decreased sensitivity) the outer side of the forearm, the skin in the middle phalanx of the thumb and index finger in the radial half of the hand.
2. When the nerve is damaged in the middle third of the shoulder, extension of the forearm is not disturbed, the elbow extensor remains intact reflex, sensitivity on the shoulder does not change, but at the same time all the other symptoms described above are present.
3. In the case of compression of the nerve at the level of the lower third of the shoulder and the upper third of the forearm (one of the most frequent variants), to break the extensor function of the muscles of the hand and fingers, there is a hypodesis of the fingers and the back surface of the hand.

Vegetative disorders in the zone of innervation are in the form of cooling, "blue", blanching of fingers, a violation of sweating of the skin.

Trophic - muscle nutrition is damaged due to nerve damage - the muscle loses weight, becomes flabby, the skin on the sick arm is dry, thin, and trophic ulcers may appear.

Syndrome of the instep

In the most frequent cases, the radial nerve can be affected in the canal of the fascia of the supinator of the forearm by squeezing the bundles of the supine muscle (supinator syndrome). It is manifested by the appearance of pain, usually in the area of ​​the elbow, the lateral surface of the forearm and the rear of the hand, are intensified more often at night. During the day, pain may occur when doing work by hand. Pain syndrome is also provoked by rotational movements of the forearm (pronation, supination). Often there may be complaints of weakness in the hand, especially the weakness of extension of the little finger, which appears during work, this leads to a violation of the coordinated movement fingers and wrists, but at the same time the wrist extension is preserved - a cardinal symptom of the difference in compression of the nerve in the duct of the instep arrestor from affecting it on the shoulder.

Radial Tunnel Syndrome

Neuropathy of the branches of the radial nerve can be at the level of the elbow and wrist joint.

Lesions of the branches of the nerve at the level of the elbow are the result of a strong compression of his bony or connective tissue with fibers of the triceps arm muscle, inflammation of the capsule elbow joint, at the wrist level - the result of injuries of the radial or ulnar bone, bone tissue tumors, pressure from the bracelet, strap from the watch or handcuffs that can cause numbness and sharp burning pain in the upper part of the forearm, the rear of the hand and fingers (or only the 1st finger), which increases during the straightening of the fingers. Hypesescence (decreased sensitivity) of the radial side of the 1st finger and muscle paresis may occur, but they are less frequent than in ulnar tunnel syndrome.

Diagnostics

Electroneuromyography will help to clarify the site of nerve damage.

It is advisable to perform some diagnostic tests for the correct diagnosis:

• the patient tightly presses the palms to each other with straightened fingers so that the wrists touch and when the wrists are extended the fingers of the affected brushes do not depart, but bend and produce sliding movements along a healthy palm, it will also be difficult to dilute the fingers;
• The rear of the hand and the fingers of the patient can not touch the flat surface at the same time;
• if you drop your hands, then on the affected arm it is impossible to remove the thumb, turn the wrist outward;
• in the position of the hand on the palmar surface it is difficult to put the third finger on the adjacent one.

More complete information about the site of nerve damage is obtained with the help of electroneuromyography (ENMG).

In the program "To live healthy!" With Elena Malysheva about the defeat of the radial nerve (see. from 3: 0 min.):

Elena Malysheva. Radiation nerve injury

Watch this video on YouTube