Nintendo thumb, also known as gamer's grip, Nintendonitis and similar names, is a video game-related health problem classified as a form of repetitive strain injury (RSI). The symptoms are the blistering, paraesthesia and swelling of the thumbs, mainly through use of the D-pad, though any finger can be affected. This can lead to stress on tendons, nerves and ligaments in the hands, and further onto lateral epicondylitis ("tennis elbow"), tendinitis, bursitis and carpal tunnel syndrome (CTS).
Some of the symptoms are described under trigger finger.
Originally known in a video gaming context as "Leather Thumb", this condition was known to occur frequently among users of 2nd generation video game consoles such as the Intellivision or the Atari 2600 in the late 1970s and early 1980s. The condition was first highlighted when the Nintendo games consoles were released, leading to reported cases of RSI, primarily in children (being one of the primary audiences of early-generation videogames). Later, the controllers for the Sony PlayStation and PlayStation 2 were noted as causing the condition. However, due to the shape, size and extended use of game controllers it is not limited to just those specific ones and can occur in users of any gamepad or joystick. Similar problems have also been observed with the use of mobile phones, and text messaging in particular (see Blackberry thumb).