Specific Imaging Findings

The imaging method of choice is CT, as these patients tend to be in very poor clinical condition. CT shows low-density edema in the brainstem and generally uncal transtentorial herniation with obliteration of the cisterns. Downward herniation is more difficult to identify, but inferior displacement of the cerebellar tonsils without a clear posterior fossa space-occupying lesion suggests it. Within the hypodense brainstem the acute hemorrhages are seen as focal areas of high density. They tend to be of a linear configuration, extending in from ventral to dorsal, but may have any shape. Hemorrhages are generally found in the pons, but may be located in the medulla and/or midbrain. Duret hemorrhage may be accompanied with other lesions in the brainstem such as shear injuries. MRI with its inherent increased sensitivity to subacute blood products may help to identify them later.

Pertinent Clinical Information

Duret hemorrhages are considered secondary brain injuries and in most patients there is a significant supratentorial abnormality leading to transtentorial herniations. Because intracranial trauma is strongly associated with these hemorrhages, they tend to be found in younger patients. Most patients are obtunded or comatose and show significant brainstem-associated findings (decerebration) which depend also upon the severity of the herniation and extent of the hemorrhages.

Differential Diagnosis

Shearing Injuries (DAI) (114)

1. • generally affect the dorsolateral aspect of the brainstem

2. • accompanied by supratentorial axonal injuries, generally not hemorrhagic and bright on DWI

Hypertensive Hematoma (177)

1. • generally larger

2. • possible history of uncontrolled hypertension

3. • no supratentorial acute abnormalities, no transtentorial herniations

4. • typically spontaneous, non-traumatic