Blackberry thumb
n.— «There’s even an informal name for the malady—”BlackBerry Thumb”—a catch-all phrase that describes a repetitive stress injury of the thumb as a result of overusing small gadget keypads.» —“Blackberry Addicts Suffer Painful Thumb Injuries” by Alicia Change in L.A. InformationWeek Oct. 20, 2005. (source: Double-Tongued Dictionary)