What sort of disease is causalgia?

Neurologic. Causalgia, now called complex regional pain disorder, is a poorly understood disorder of the nerves in the arms or legs. Most commonly it is brought on by physical trauma to an arm or leg that then becomes very painful to touch or to use, especially in the hand or foot. The pain can persist long after the original injury is healed. Early diagnosis helps but it remains difficult to treat or cure.
Nerve injury. Causalgia is a type of nerve pain with increased pain and sympathic nerve system dysfunction after an injury of a larger nerve, that is a merve with an anatomic name. You need to see a pain medicine specialist!