Brachial plexopathy is another well recognised but not much publicised side-effect of sympathectomy

Brachial plexus dysfunction (brachial plexopathy) is a form of peripheral neuropathy. It occurs when there is damage to the brachial plexus, an area on each side of the neck where nerve roots from the spinal cord split into each arm's 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 (especially from lung tumors), or damage that results from radiation therapy.

Brachial plexus dysfunction may also be associated with:

• Birth defects that put pressure on the neck area
• Exposure to toxins, chemicals, or drugs
• General anesthesia, used during surgery
• Inflammatory conditions, such as those due to a virus or immune system problem

In some cases, no cause can be identified.

Symptoms

• Numbness of the shoulder, arm, or hand
• Shoulder pain
• Tingling, burning, pain, or abnormal sensations (location depends on the area injured)
• Weakness of the shoulder, arm, hand, or wrist

http://www.nlm.nih.gov/medlineplus/ency/article/001418.htm