Tinel’s sign is a way to detect irritated nerves. It is performed by lightly tapping (percussing) over the nerve to elicit a sensation of tingling or ”pins and needles” in the distribution of the nerve. In carpal tunnel syndrome where the median nerve is compressed at the wrist, Tinel’s sign is often ”positive” causing tingling in the thumb, index, middle finger and the radial half of the fourth digit.