Brachial nerve plexus root impingement

Brachial plexus root entrapment or, as it is often said, brachial nerve entrapment, is a rather serious neurological lesion, since the network of intersecting nerves of this anatomical region transmits signals from the spinal cord to the upper extremities, responsible for motor (motor or muscular) and sensory (that is, skin sensory) innervation of the shoulder, arm and hand.

Epidemiology

The incidence of brachial nerve plexus injury in motor vehicle accident-related injuries is reported to exceed 40%.

Postoperative brachial plexus injury is reported in 12-15% of cases.

The prevalence of tumor compression on the roots of the plexus brachialis is estimated to be 0.4-1.2%.

And the statistics for the development of brachial plexus palsy in newborns: 0.4-5% of cases for every thousand live births. [1]

Causes of the brachial nerve entrapment

Considering the etiology of nerve root impingement of the brachial plexus (plexus brachialis) - without referring to the short and long lateral branches coming out of it at various points, it should be recalled that this peripheral plexus is formed by the ventral (anterior) branches of the spinal nerves (cervical C5-C8 and first thoracic T1) and extends from the base of the neck to the axilla. spinal nerves (cervical C5-C8 and first thoracic T1) and extends from the base of the neck to the axilla, passing between the anterior and medial staircase muscles (musculus scalenus). And its motor and sensory roots are the above paired spinal nerves, which exit the spinal cord through the intervertebral foramen at the level of the lower cervical and upper thoracic vertebrae. [2]

The key causes of root compression lesions - pinching or compression - may be due to:

• brachial plexus injury and joint and/or musculoskeletal injuries, including birth injuries (obstetric brachial plexus injury); [3]
• habitual dislocation of the shoulder joint;
• increased physical stress on the shoulder girdle;
• Cervicothoracic spine vertebral osteochondrosis with development of anterior ladder muscle syndrome; [4]
• elongated (hypertrophied) spinous process of the seventh cervical vertebra (C7) - the most protruding in the neck region;
• thoracic outlet syndrome (compression of the nerve roots between the clavicle and the first rib); [5], [6]
• growing brachial plexus tumor, particularly schwannoma, neurofibroma, neurosarcoma, and metastases of primary pulmonary carcinoma.

Risk factors

Risk factors for brachial nerve entrapment (brachial plexus roots) include:

• traffic accidents;
• falls with contusions, dislocations and fractures of the shoulder joint, lower cervical vertebral joints or clavicle;
• Frequent carrying of heavy objects, including in a shoulder strap bag or backpack;
• engaging in contact sports, particularly soccer and wrestling;
• surgical interventions in the brachial plexus area.

In infants, the risk of impaction is increased with a difficult delivery, which can be due to high birth weight, malposition or dystocia of the fetal shoulders, and a narrow pelvis of the birthing woman.

Pathogenesis

Specialists note the vulnerability of nerve roots to compression, as their epineurium (outer layer) is poorly developed, and the connective tissue sheath (perineurium) is absent. [7]

Compression neuropathies are caused by direct pressure on nerves. In fact, pinching of nerve roots (including the brachial plexus) leads to the development of compression ischemic neuropathy with impaired nerve fiber tissue nutrition, which negatively affects their function. And the pathogenesis of pinch neuropathic pain, muscle (motor) and sensory disorders lies in partial or complete blockade of nerve conduction. [8], [9]

Symptoms of the brachial nerve entrapment

The first signs of impingement in the form of radicular syndrome depend on which radicle is being compressed and its innervation zones (muscles and dermatomes).

For example, pinching of the C5 root, which is responsible for innervation of the upper arm muscles and part of the shoulder muscles, weakens the deltoid muscle of the shoulder and part of the biceps (bending and extending the arm at the elbow joint) and reduces the sensitivity of the skin of its outer surface up to the elbow, causing tingling or burning, as well as loss of skin sensitivity - numbness. The pain may radiate to the shoulder.

In case of compression of the root C6 of the brachial plexus, symptoms are manifested by pain in the shoulder and forearm (which increases with movements of the arms or neck); paresthesia or numbness of the outer side of the forearm, thumb and index finger; decreased strength or complete loss of muscle reflexes of the biceps brachii muscle.

If the C7 root is pinched, there is a loss of skin sensation down the back of the hand to the index and middle fingers, a decrease in the triceps reflex (the triceps muscle of the shoulder that straightens the elbow), and pain in the shoulder and forearm (on the posterior surface), which can go under the shoulder blade.

Symptoms of C8 and T1 root impingement include pain in parts of the shoulder, forearm, hand, and little finger; progressive weakness in the wrist, hand, or fingers; and numbness in the forearm or hand.

A pinched nerve in the shoulder joint is accompanied by pain in the shoulder and neck (especially when turning the head from side to side), numbness and muscle weakness in the arm and hand (tenar muscles of the palm), leading to difficulty in lifting the arm and fine motor skills.

Read also - Brachial plexus lesion syndromes

Complications and consequences

Complications of brachial nerve (brachial plexus root) pinches can be very serious, and some effects can be irreversible.

For example, pain resulting from nerve root damage can become chronic to the point of caesalgia, and limitation of arm or hand mobility leads to what is known as joint stiffness, which exacerbates the difficulty in moving the limb.

Compression of nerve fibers causes not only denervation of muscles, but also their gradual atrophy.

Severe trauma to the brachial plexus with pinching of its roots can lead to paralysis of the arm and disability.

Diagnostics of the brachial nerve entrapment

Physical examination by a neurologist (with assessment of range of motion on the affected side) and anamnesis are complemented by mandatory instrumental diagnostics, including X-ray of the shoulder joint and shoulder, X-ray of the cervical spine, ultrasound of the brachial plexus area, electromyography and electroneuromyography (nerve conduction study). If necessary, a CT scan or MRI is performed. [10]

Differential diagnosis

Differential diagnosis should exclude brachial plexitis, inflammatory diseases of the shoulder joint, impingement of roots C1-C4 of the cervical plexus (cervical radiculopathy), cervical facet joint syndrome, tunnel syndromes, myofascial syndrome, upper thoracic aperture compression syndromes, endocrine peripheral neuropathies, autoimmune motoneuron diseases, etc.

Treatment of the brachial nerve entrapment

Once diagnosed, most cases of brachial nerve entrapment are treated at home.

The main pharmacological drugs are symptomatic: pain pills - non-steroidal anti-inflammatory drugs (NSAIDs) with analgesic effect, such as Paracetamol, Ibuprofen and other neuralgia pills

Corticosteroid injections may also be prescribed to relieve pain.

To restore motor functions and expand the range of motion of the arms and hands, physiotherapy is used: physical therapy and massage for pinched brachial nerve.

Read more in the publications:

• Treatment of upper extremity neuropathy
• Treatment of neuropathic pain
• Hand numbness treatment

In addition, it can be carried out herbal treatment with the use of: extract of swamp aira root (Acorus calamus) - as an analgesic, Ginkgo biloba - to improve tissue trophism and reduce oxidative stress, as well as increasing the conduction of nerve impulses in the CNS, sage (Salvia officinalis) - as a means of strengthening the nervous system.

Prevention

More often than not, brachial plexus injury cannot be prevented except by limiting physical activity on the shoulder girdle.

Forecast

In relatively minor brachial plexus injuries, the prognosis is more favorable, because in such cases 90% of patients can normalize mobility and sensitivity of the upper extremities with proper treatment. Severe injuries are characterized by chronic dysfunction of the roots of the brachial plexus.