(also spelled, Duret hemorrhages
) are small areas of bleeding in the ventral and paramedian
parts of the upper brainstem
It is named for RL Duret.
They are secondary to raised intracranial pressure
with formation of a transtentorial
pressure cone involving the cerebral peduncles (crus cerebri
) and other midbrain structures caused by raised pressure above the tentorium
Kernohan’s notch is a groove in the cerebral peduncle that may be caused by this displacement of the brainstem against the incisura of the tentorium. The resulting ipsilateral hemiparesis is a false localising sign, known as the Kernohan-Woltman syndrome. This may succeed or accompany temporal lobe (uncal) herniation and subfalcian herniation secondary to a supratentorial mass.
The common causes are an acute haematoma
, or tumour
Imaging can be difficult.
The Duret haemorrhage is demonstrated at CT
It usually indicates a fatal outcome. However, survival has been reported.
The mechanism is uncertain but is probably caused by the displacement of the brainstem
stretching and lacerating pontine
perforating branches of the basilar artery
; venous infarction
may play a role.