Acute brachial neuritis is a form of peripheral neuropathy. It occurs when there is damage to the brachial plexus, an area where a nerve bundle from the spinal cord splits into the individual arm nerves.

Damage to the brachial plexus is usually related to direct injury to the nerve, stretching injuries (including birth trauma), pressure from tumors in the area, or damage that results from radiation therapy.

Acute brachial neuritis may also be associated with:

• Birth defects (that put pressure on the neck area).
• Exposure to toxins, chemicals, or drugs.
• Inflammatory conditions, such as those due to a virus or immune system problem.
• In some cases, it is idiopathic.