The "facie sympathique" sign in hanging: historical background, forensic review, and perspectives.

The "facie sympathique" is a vital sign first described by Etienne Martin in 1899 referring to unilateral miosis, with or without ptosis, at the opposite side from the knot in hanging. This mark is scarcely reported in legal medicine textbooks and scientific papers. Moreover, when cited, it is referred to differently from its original meaning, both as unilateral contraction (miosis) and dilatation (mydriasis) of the pupil depending on the antemortem firmness of the ligature's neck pressure in hanging with little attention to ptosis. Due to the sympathetic nervous pathway supplying the eye, the review of this ocular sign in hanging supports the importance of revitalizing the "facie sympathique" in research on lesion vitality in mechanical asphyxia.