Anatomical cerebellar protection of contrecoup hematoma development. Analysis of the mechanism of 30 posterior fossa coup hematomas

Abstract 

The aim of this paper is to present the topographical/anatomical conditions that protect the posterior fossa from posterior fossa hematoma (PFH) resulting from contrecoup mechanisms and to point out the value of neuroradiological findings in determining force direction and transition. The biomechanism of this clinical entity also plays an important role in correct forensic interpretation. Generally, PFH are rare. In our series, they occurred exclusively as a result of forces applied to the occipital region. However, their appearance as a result of contrecoup mechanisms is exceptional. Considering the particular anatomical traits that protect the posterior fossa from the force transition of fronto-occipital (F-O) direction we put forth seven hypotheses which should explain the low incidence of PFH. Between 1989 and 1998, we treated 523 patients with intracranial hematomas caused by blunt trauma. Among them were 30 patients with PFH. All of them sustained an occipital bone fracture, confirming the coup lesion. In conclusion, it is difficult to determine clinically whether forces in the F-O direction could produce PFH as a result of contrecoup mechanism. That could be only proven in vivo by neuroradiological findings.