The Collaborative International Dictionary of English v.0.48:

Vellication \Vel`li*ca"tion\, [L. vellicatio.]
   1. The act of twitching, or of causing to twitch.
      [1913 Webster]

   2. (Med.) A local twitching, or convulsive motion, of a
      muscular fiber, especially of the face.
      [1913 Webster]

WordNet (r) 3.0 (2006):

vellication
    n 1: a sudden muscle spasm; especially one caused by a nervous
         condition [syn: twitch, twitching, vellication]