[citation needed] They are caused by a traumatic downward displacement of the brainstem with parahippocampal gyrus herniation through the tentorial notch.

[citation needed] Kernohan's notch is a groove in the cerebral peduncle which may be caused by this displacement of the brainstem against the tentorial incisure.

[citation needed] The pathophysiological mechanism is uncertain[7] but is probably caused by the displacement of the brainstem stretching and tearing perforating branches of the basilar artery to the pons; venous infarction may play a role.

[citation needed] Duret haemorrhages can be demonstrated by medical imaging techniques of CT or MRI though difficult.

The fact that he had suddenly collapsed and become comatose when he stood up on his last day of life, has been interpreted as brain herniation and Duret haemorrhages.