When two fracture lines of a solid surface (ice, glass, eggshell, etc.) intersect, it is always possible to tell which one has been made first. Indeed pre-existing damage of the surface arrests all the fracture lines produced by subsequent impacts. This well-known principle (established by Puppe in 1903) has been largely used in glass fracture analysis, but can be applied also to the examination of skull fractures. It can help sequencing blunt force or gunshot injuries determining the direction of fire and differentiating entrance from exit wounds in the absence of specific distinguishing features (i.e., internal/external beveling of the skull or overlying skin indicators). In this context, we report the case of a 76-year-old man who shot himself in the mouth with a Walther PPK 7.65 handgun and highlight the utility of the application of both Puppe's Rule and Multislice Computed Tomography (MSCT) in the examination of gunshot wounds to the skull.
