Axillary nerve dysfunction Health Article

Definition

Axillary nerve dysfunction is a loss of movement or sensation of the shoulder because of nerve damage.

Alternative Names

Neuropathy - axillary nerve

Causes, incidence, and risk factors

Axillary nerve dysfunction is a form of peripheral neuropathy. It occurs when there is damage to the axillary nerve, which supplies the deltoid muscles of the shoulder. A problem with just one nerve group, such as the axillary nerve, is called mononeuropathy.

The usual causes include direct trauma, prolonged pressure on the nerve, and compression of the nerve from nearby body structures. Entrapment involves pressure on the nerve where it passes through a narrow structure.

The damage may include destruction of the myelin sheath of the nerve or destruction of part of the nerve cell (the axon). Damage to the axon slows or prevents conduction of impulses through the nerve.

Direct injury to the shoulder and pressure on the nerve can lead to axillary nerve dysfunction.

Conditions associated with axillary nerve dysfunction include:

• Fracture of the upper arm bone
• Pressure from casts or splints
• Improper use of crutches
• Shoulder dislocation
• Body-wide disorders that cause nerve inflammation

In some cases, no cause can be identified.

Symptoms

• Numbness over part of the outer shoulder
• Shoulder weakness
• Difficulty lifting objects with the sore arm
• Difficulty lifting arm above the head

Signs and tests

Your health care provider will examine the arm and shoulder. There may be weakness of the shoulder with difficulty moving the arm.

The deltoid muscle of the shoulder may show signs of muscle atrophy.

Tests that reveal axillary nerve dysfunction may include:

• EMG -- will be normal right after the injury; it should be performed several weeks after the injury or symptoms start
• Nerve biopsy
• MRI