The curious synalgia of Henri Gourdan de Fromentel (1858-1914)

In 1883, Henri Gourdan de Fromentel defended his thesis on an original topic that has not really been studied since. He examined the simultaneous perception of pain in two distinct and distant, but homolateral, areas of the body following a single stimulation on himself. In the discussion he compared his synalgia with other types of synaesthesia that did not involve pain and concluded that it was likely to be of central nervous system origin. After a brief account of Fromentel's life, this article discusses his thesis and a book on the subject he published five years later in the light of current understanding of the phenomenon and the proximity of synalgia and allachaesthesia.