What is the role of the rate of injury acceleration-deceleration in the pathogenesis of subdural hematoma (SDH)?

Updated: Jul 26, 2018
  • Author: Richard J Meagher, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

t has been asserted that the primary brain injury associated with subdural hematoma plays a major role in mortality. However, most subdural hematomas are thought to result from torn bridging veins, as judged by surgery or autopsy. Furthermore, not all subdural hematomas are associated with diffuse parenchymal injury. As mentioned earlier, many patients who sustain these lesions are able to speak before their condition deteriorates—an unlikely scenario in patients who sustain diffuse damage.

Using a primate model, Gennarelli and Thibault demonstrated that the rate of acceleration-deceleration of the head was the major determinant of bridging vein failure. By using an apparatus that controlled head movement and minimized impact or contact phenomena, they were able to produce acute subdural hematomas in rhesus monkeys. In all cases, the sagittal movement of the head produced by an angular acceleration caused rupture of parasagittal bridging veins and an overlying subdural hematoma.

Gennarelli and Thibault reported that their results were consistent with the clinical causes of subdural hematoma, in that 72% are associated with falls and assaults and only 24% are associated with vehicular trauma. The acceleration (or deceleration) rates caused by falls and assaults are greater than those caused by the energy-absorbing mechanisms in cars, such as dashboard padding, deformable steering wheels, and laminated windshields. [4]


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