Pinched radial nerve of the right, left arm

Compression or entrapment of the radial nerve, one of three nerves in the brachial plexus that provide motor and sensory function to the arms, leads to the development of compression neuropathies, including tunnel syndromes. [ 1 ]

Epidemiology

According to some clinical data, the annual detection of radial nerve entrapment in the diagnosis of compression neuropathies is: 0.03% - compression of the posterior interosseous branch, entrapment of the superficial branch - 0.003%. [ 2 ]

For comparison: carpal tunnel syndrome, caused by compression of the median nerve, is detected in 0.1-0.3% of patients with neuropathies of the upper extremities; compression of the ulnar nerve (in the form of cubital tunnel syndrome) is diagnosed in 0.03% of cases.

Mononeuropathy of the radial nerve, as a result of its compression, is observed in almost 12% of patients with humeral fractures. [ 3 ]

Causes radial nerve entrapment

Pinched radial nerve is diagnosed quite rarely due to the similarity of the clinical picture with other types of neuropathy of the upper extremities. [ 4 ]

Compression can occur anywhere along the radial nerve (nervus radialis) and can have various etiologies.[ 5 ]

Among the causes and risk factors for its pinching, experts note:

• long-term traumatic effects of repetitive pronation and supination of the wrist and flexion-extension or swinging movements of the forearm, often associated with sports and professional activities;
• fracture of the lower or middle part of the humerus (including the development of post-traumatic periostitis in the area of the middle third of the shoulder, to which the nerve is adjacent);
• dislocation of the radius or elbow joint, a strong blow to the outer back of the elbow;
• swelling of the forearm tissues after the installation of structures for the correct fusion of a fracture of the humerus;
• previous operations on the upper limb for shoulder instability, carpal tunnel syndrome, deforming arthrosis and osteoarthritis of the hand and finger joints;
• prolonged or incorrect use of crutches;
• the presence of cortical hyperostosis, osteoma, connective tissue tumor (lipoma) and other formations at the site of the nerve passage.

The most likely causes of radial nerve entrapment in the hand are injuries, chronic overexertion of the wrist joint, wearing a tight watch strap or bracelet, the presence of a wrist hygroma pressing on the nerve, that is, a synovial cyst in the area of the dorsal carpal ligament, where the nerve branch passes through the radial canal of the wrist (canalis carpi radialis). [ 6 ], [ 7 ]

Pathogenesis

The compressive action not only causes ischemia of the nerve fiber (i.e. the blood flow to the cells decreases), but also deforms its structure. And in case of injuries, local edema and reactive inflammation occur.

And the pathogenesis of syndromic forms of radial nerve entrapment is caused by temporary blockade of nerve impulse conduction – due to a decrease in the amplitude of the action potential during depolarization of the cell membranes of neurons. At the same time, the processes of nerve cells (axons) remain intact. [ 8 ]

Long-term nerve compression can lead to focal thinning of the myelin sheath and even myelin loss, with irreversible damage to the nerve and loss of its function.

Symptoms radial nerve entrapment

Clinically, the symptoms of damage to the radial nerve and its branches vary depending on the location of the pinching. And the first signs can manifest themselves for quite a long time as a disturbance of sensitivity.

When the radial nerve is compressed in the area of the brachial axillary angle (in the upper third of the shoulder), the sensitivity of the skin of the back of the arm from the shoulder to the thumb and, partially, the index and middle fingers decreases; it is difficult to bend and straighten the arm at the elbow. A characteristic symptom is a drooping wrist – due to paresis of the forearm muscles that provide extension of the wrist.

If the radial nerve is pinched in the brachioradialis canal (canalis humeromuscularis), which is also called (spiral), in the area of the septum between the brachialis and brachioradialis muscles (in the middle of the shoulder) or closer to the lateral epicondyle of the humerus, then - in addition to all the listed symptoms - there is the inability to rotate the forearm in the outward direction and intense neuralgic pain that accompanies extension of the arm. [ 9 ]

Pinching of the superficial branch of the radial nerve (with paresthesia and pain in the back of the hand and base of the thumb) is most often observed at its transition from the shoulder to the forearm - in the tunnel located under the tendon of the brachioradialis muscle (musculus brachioradialis).

Compression of the radial nerve at the top of the forearm (in the subcubital region) in most cases occurs when it passes through the fibrous ring - Froese's arcade - at the beginning of the canal of the supinator fascia of the forearm (canalis supinatoriu). Patients with such localization of compression complain of weakness and limited mobility of the hand and fingers, pain on the back of the wrist and in the arm below the elbow (increasing at night). The diagnosis can be defined as supinator syndrome or Froese syndrome.

Typical symptoms of radial nerve entrapment in the wrist area, in addition to paresthesia (numbness) of the back of the hand, include numbness and periodic burning pain in the thumb, index and middle fingers.

As a result of pinching of the radial nerve in the hand - in the area of the radial fossa (the depression near the base of the thumb) - local sensory disturbances and problems with the mobility of the thumb are observed. [ 10 ]

It should be borne in mind that tremors in the hand are not associated with a pinched nerve: there are other reasons for this. More details in the material - When hands shake.

Complications and consequences

The main consequences and complications associated with the disruption of nerve impulse conduction when the radial nerve is pinched are the development of compression ischemic neuropathy, which is often defined as radial tunnel syndrome.

In addition to significant limitation of mobility of the upper limb (which cannot always be fully restored), gradual atrophy of the muscles of the shoulder and forearm may occur.

Diagnostics radial nerve entrapment

The patient's complaints and history are an integral part of diagnosis, but diagnosing radial nerve compression even on the basis of symptoms can be difficult.

Therefore, in clinical neurology there is a system of functional tests (tension of the supinator muscle when bending the wrist, elbow deviation, pronation, etc.), which each patient undergoes.

To clarify the degree of compression damage to the nerve, instrumental diagnostics are carried out by studying nerve conduction using electroneuromyography.

And to identify pathological changes along the nerve, as well as visualize possible formations compressing the nerve, ultrasound or MRI is performed. [ 11 ]

Differential diagnosis

The list of diseases that should be taken into account in differential diagnostics includes: Quervain's tenosynovitis, arthritis of the thumb, radiculopathy of the sixth cervical vertebra, lateral epicondylitis (chronic inflammation of the tendons of the extensor muscles of the forearm), inflammation of the bursa of the wrist joint (bursitis), inflammation of the synovial membrane of the wrist joint, damage to the entire brachial plexus (trauma or inflammation).

Treatment radial nerve entrapment

Conservative treatment involves immobilization of the limb (temporary application of a splint) to relieve stress from the sore arm.

The main medications are painkillers. In order to not only relieve pain but also reduce swelling in cases of nerve compression in the spiral and other radial tunnels, neurologists recommend taking nonsteroidal anti-inflammatory drugs (NSAIDs) - Ibuprofen and its analogues.

More information - Neuralgia pills

Injections of corticosteroids (hydrocortisone) may be prescribed, which provide relief within one to one and a half months in almost 70% of cases, but do not guarantee complete relief from neuropathy symptoms.

The drug of the anticholinesterase parasympathomimetic group Amiridin (other trade names - Axamon, Neuromidin) is used by injection, which helps improve neuromuscular transmission. Contraindications to its use include bronchial asthma, angina, decreased heart rate, intestinal obstruction, exacerbation of gastric ulcer and / or duodenal ulcer. And among the side effects are noted: general weakness, dizziness and heart rhythm disturbances; increased secretion of saliva, sweat and bronchial secretions; allergic reactions. [ 12 ]

It is recommended to take B vitamins, as well as vitamin N – lipoic acid.

Almost the entire complex of procedures used in physiotherapy treatment, which is mandatory for neuropathies (according to the treatment protocol), includes electro-impulse stimulation, exercise therapy, massage, etc. This issue is covered in detail in the article – Physiotherapy for neuritis and neuralgia of peripheral nerves. [ 13 ]

The last option – surgical treatment – is carried out when conservative therapy, including courses of physiotherapy, has not yielded positive results over 12 months. Surgical intervention consists of decompression of the trunk or branch of the ulnar nerve (for example, excision of scar tissue), as well as tendon or muscle transposition. More information in the material – Surgical methods of pain treatment

As experts note, good results of such operations are achieved, on average, in 70% of cases, and rehabilitation can continue for up to one and a half years – to restore motor and sensory functions. In this case, the key condition for successful rehabilitation is the performance of physical exercises, individually prescribed by a specialist. [ 14 ]

Folk remedies

What can folk remedies offer in this case? Relief of pain and swelling with the help of:

• alternating warm and cold compresses on painful areas; one is a light massage of the same areas with warmed camphor or mustard oil (with the addition of a few drops of essential oils of rosemary, thyme or lavender);
• performing exercises that stretch and relax the muscles of the shoulder and forearm.

To treat numbness in the hands, it is recommended to apply warming compresses, alternating them with cold ones.

Herbal treatments, the effectiveness of which for this pathology is questionable, include:

• compresses with a decoction of autumn crocus bulbs (which is a poisonous plant);
• compresses from fresh cabbage leaves (with honey), burdock leaves or garden geranium;
• with oral administration of decoctions/water infusions of peppermint, birch leaves or valerian roots.

Prevention

It is almost impossible to insure against nerve entrapment, but to minimize the risk of compression of the nervus radialis, prolonged elbow extension with pronation (rotation) of the forearm and flexion of the wrist should be avoided.

Forecast

Only timely and correct treatment makes it possible to give a positive prognosis for pinched nerves, including the radial nerve. [ 15 ] And recovery can take months or even years.