The first monograph exclusively on trigeminal neuralgia, which Pujol called “tic douloureux”, or painful tic, as it had originally been designated by Caelius Aurelianus. Pujol provided a valuable description of the symptoms that helped his contemporaries make an exact diagnosis, even though he did not offer proven treatments.  He stressed the difficulty in differentiating the facial pain of tic douloureux from toothache. He also proposed a novel pathophysiological theory of pain.