The brachial plexus is a group of nerves between the neck and shoulders. These nerves activate the muscles and provide feeling from the shoulders to fingertips. Brachial plexus injury (BPI) is a severe peripheral nerve injury causing weakness or inability to use certain muscles in your hand, arm or shoulder and thereby causing functional damage and physical disability.

Most brachial plexus injuries in adults are due to –

• Forehead Frown Lines – Frown lines, also referred to as wrinkles, worry lines, forehead furrows, glabellar lines, or “the 11s,” that are deep vertical lines that
  develop on the forehead.
• Traffic accidents
• Motorcycle collisions
• High-impact traumatic accident
• Heavy fall with stretching of neck
• Industrial trauma – weight falling on shoulder from a height or being dragged
  inside a machine by the arm
• Assault with a sharp object like knife

Surgery will be effective, if done within six months in case of severe injury to the brachial plexus. After the stated period, the muscle fibers may no longer be capable of communicating with nerves, even if nerve signals are restored.