for repetitive stress injuries, these ailments result from recurrent large or small movements that affect joints, muscles, tendons, and nerves. For example, people who frequently use their thumbs to type text messages on cellphones sometimes develop de Quervain syndrome, a painful affliction that involves the tendons that move the thumb. Although the causal link isn't as well established as in patients who suffer from pain from prolonged desktop keyboard use, there's little doubt that overzealous texting can cause debilitating pain.