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

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.

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.

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

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
• Nerve biopsy
• MRI