Radial nerve dysfunction is a problem with the movement or sensation of the back of the arm (triceps), forearm, or hand.

Radial nerve dysfunction is a form of peripheral neuropathy. It occurs when there is damage to the radial nerve, which travels down the arm and controls movement of the triceps muscle at the back of the upper arm. It also controls extension of the wrist and helps in the movement and sensation of the wrist and hand.

Dysfunction of a single nerve group (such as the radial nerve) is called mononeuropathy (mono means "one," and neuropathy means "nerve damage"). With mononeuropathy usually the nerve damage is caused locally. However, systemic disorders (such as mononeuritis multiplex) may occasionally cause nerve damage.

Causes include:

• Injury
  • "Crutch palsy," caused by improper use of crutches
  • Fracture of the humerus (upper arm bone)
  • Long-term or repeated constriction of the wrist (caused by wearing a tight watch strap, for example)
  • Pressure caused by hanging the arm over the back of a chair
  • Pressure to the upper arm from arm positions during sleep or coma
  • "Saturday-night palsy" (when the arm is in a position that pinches the nerve during deep sleep, such as when a person is intoxicated)
• Long-term pressure on the nerve
• Pressure on (compression of) the nerve caused by swelling or injury of nearby body structures

These factors may be complicated by a lack of oxygen from decreased blood flow (ischemia) in the area.

In some cases, no cause can be found.