If you have numbness in your arm after breast cancer surgery, if you have numbness for a short period of time, it may be due to the position you were in during the surgery. If the numbness is prolonged, the surgery may have damaged the intercostal brachial nerve and the sensory nerves that innervate the upper limbs. Nerve injury is usually a long-term injury, and recovery is slow. Sensory nerve function can be restored through rehabilitation exercises, such as appropriate extension and pull-up exercises for the upper limbs.