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6202594 
Book/Book Chapter 
Chapter 14 - Factors Affecting the Formation of Epidural Hematomas 
Ganz, JC 
2018 
Academic Press 
Intracranial Epidural Bleeding 
175-188 
The first event in the formation of an epidural hematoma (EDH) is an initial dura separation from the skull. Nineteenth-century research by Bell and Erichsen documented this. Further research by Milroy Paul suggested that the area separated was limited. His work together with that of Marchant mentioned an area where the dura was relatively easy to detach. Russian work also documented the wide variability of the attachment of the dura to the skull. There has been ongoing debate since the time of Charles Bell concerning secondary separation of dura by bleeding from a meningeal artery. Bell denied it. Erichsen and Paul provided evidence for its occurrence. Ford and Mclaurin defined the area of initial dura separation and the necessary force across the dura to permit secondary separation. However, they also suggested this was not an important mechanism and that secondary deterioration was the result changes in the brain after cessation of bleeding. Findings in this chapter support this notion. The role of veins in EDH is discussed. It is proposed that venous rupture could fill an initial pocket made by dural separation but that the veins could never strip further dura from the skull. The veins were also shown to provide the basis for an arteriovenous shunt leading blood from the epidural space back to the cervical veins. This shunt could form a physiological basis for a lucid interval. Thus, the current evidence is that secondary bleeding can separate the dura and increase the EDH volume. Clinical changes can be the result of both the arteriovenous shunt and intradural changes. 
Epidural bleeding; epidural arteriovenous shunt; initial dura separation; secondary dura separation; lucid interval 
Ganz, Jeremy Christopher