Exception to the Puppe's rule reloaded and a warning in the interpretation of skull fractures: they run even through recent craniotomy burr holes.

A possible "exception" to Puppe's rule regarding the intersection of skull fractures has been previously addressed due to the observation that skull fractures can pass through old and remodeled craniotomies. In a further case presented herein, however, it was shown that cranial fractures are also able to pass through recent burr holes, a phenomenon never previously described. A 63-year-old man sustained a self-inflicted gunshot wound to the right temple region, with an exit wound in the left temporal region. Twenty-five days prior, the patient had undergone parietal craniotomy for the evacuation of a subdural hematoma secondary to glioblastoma. Among the fracture lines originating from the exit wound, one traversed the craniotomy hole, terminating approximately 1.4 cm beyond its contralateral margin. This illustrates that cranial fractures possess the capability to cross "fresh" burr holes that have not undergone to bone remodeling. Consequently, the evaluation of Puppe's rule should be reconsidered, particularly in cases of gunshot injuries, wherein fractures pass through full-thickness circular lesions (such as entry and exit wounds). The varied scenarios underscore the potential for fractures to "pass through" these burr holes if they have not themselves generated fracture lines, as may be the case with entry holes with circular lesions without fractures.