Duret haemorrhages

Duret haemorrhages are small linear areas of bleeding in the midbrain and upper pons of the brainstem. They are caused by a traumatic downward displacement of the brainstem.^[1]

Duret haemorrhages
Brainstem

They are named after Henri Duret.

Causes

Duret haemorrhages are named after Henri Duret,^[2] who discovered these brainstem lesions in dogs with increased intracranial pressure.^[3] They are small linear areas of bleeding in the midbrain and upper pons of the brainstem.^{[citation needed]}

They are caused by a traumatic downward displacement of the brainstem with parahippocampal gyrus herniation through the tentorial notch.^[4] or acute hematoma, edema following trauma, abscess, or tumor.^{[citation needed]}

Pathogenesis

Duret haemorrhages are haemorrhages secondary to raised intracranial pressure with formation of a transtentorial pressure cone involving the front part of the cerebral peduncles, the cerebral crura. Increased pressure above the tentorium may also involve other midbrain structures.^{[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. The resulting ipsilateral hemiparesis is a false localising sign,^[5] known as the Kernohan-Woltman syndrome.^[6] This may succeed or accompany temporal lobe (uncal) herniation and subfalcian herniation secondary to a supratentorial mass.^{[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]}

Diagnosis

Duret haemorrhages can be demonstrated by medical imaging techniques of CT or MRI though difficult.^[8]

Prognosis

Duret haemorrhages usually indicate a fatal outcome.^[9] However, survival has been reported.^[10][11]

Society and culture

George Gershwin died after emergency surgery of a large brain tumour, believed to have been a glioblastoma. 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.^[12]