Commentary on: Crudele GDL, Merelli VG, Vener C, Milani S, Cattaneo C. The frequency of cranial base fractures in lethal head trauma. J Forensic Sci doi: 10.1111/1556‐4029.14149. Epub 2019 Aug 21.

Abstract

Editor, We have read with great interest the recently published article by Graziano D.L. Crudele et al. (1), observing the distribution of cases of death according to manner of death and manner of injury and number of fossae involved, for analyzing the frequency of cranial base fractures in lethal head trauma. The authors focused on the proportion of base fractures associated with vault fractures, and the frequency of absence of base fracture in subjects with no vault fractures and concluded the interesting associations of base fractures to age and manner of death. We utterly appreciate the merit of the proposed investigation. Besides, we especially interested in the 69 case records of base fractures but with no vault fractures and the storage conditions before autopsy. Regarding three cases of skull base fractures induced by refrigeration we reported several years ago (2), the cause of death was none of skull–brain injuries associated with and the differential between antemortem and postmortem basilar fractures was concluded. Though we agree with the analyzed conclusion made by Graziano D.L. Crudele et al., additional information on storage conditions and distinguishment and description of base fractures would be better for such occasion. The bone structure is relatively loose and osteoporotic in the sella area. In addition, brain tissue hold “anomalous expansion” factor exhibiting a “cold bilges heat shrink” abnormal phenomenon within 0–4°C due to containing mostly water according to common physical knowledge. Once volume of water increases by 1/10 to the maximum when condensing into ice at 0°C, the brain tissue volume obviously increases. As the cranial cavity is a relatively closed structure, the weak basilar part of the skull ruptures because of the increased volume of brain tissue and the intracranial pressure. Together with another six cases reported cases on Forensic Journals within China, the characteristics of basilar fracture due to frozen corpses can be summarized as following: (1) Usually single and simple shape of basilar fracture was observed, probably a linear fracture, a half ring, or a ring fracture; (2) the fracture is of limited range in especially weak structures, like anterior cranial fossa sieve plate, and orbital plate; (3) because of the direction of the force from encephalic to extracranial, fracture fragment shifts, or collapses in the same direction as for annular or comminuted fractures without bleeding at the fracture site or at surrounding tissue; and (4) other rules include no violence involved, no bleeding or “raccoon sign” around the upper and lower eyelids, and no cerebrospinal fluid leaking out. Furthermore, how antemortem differs from postmortem basilar fracture is concerned. Antemortem basilar fracture would involve either anterior, middle, or posterior cranial fossa, producing a linear fracture, or with any complex variations. The fracture lines are in the same direction of the force, and the fracture zone corresponds to brain tissue rupture, bleeding, and so on.