"abnormal sensitivity to pain," 1854, from hyper- "over, exceedingly, to excess" + ending probably based on analgesia. Related: Hyperalgesic.
Hyperaesthesia, then, is the peculiar state in which the absolute sensibility is increased--the minimum of stimulation needed to excite perception being less than normal. Hyperalgesia is where stimuli which normally cause only a slight sensation give rise to pain in consequence of the lowering of the pain minimum. ["The Medical Record," April 1, 1867]