A jet or flame-shaped hemorrhage is a term sometimes used to describe an intraparenchymal hematoma adjacent to a ruptured arterial vascular malformation, such as aneurysms (most common) or dural arteriovenous fistulae or arteriovenous malformations 1,2. It usually is seen in combination with subarachnoid hemorrhages, intraventricular hemorrhages or subdural hemorrhages, although rarely they can be seen in isolation 3. It is particularly in this latter scenario that recognition of the shape is helpful in guiding additional imaging.
On this page:
Terminology
The use of the term "jet" or "flame" to describe hematomas is not very common in the published literature, and flame hemorrhage most commonly refers to a subset of retinal hemorrhages. Nonetheless, given the importance of this finding, it is worth using it as an aid memoir.
It should also be noted that the term flame-shaped hemorrhage has been used by some authors to denote the pattern of hemorrhage in venous infarcts 4.
Pathology
These hematomas result from the rupture of an aneurysm that abuts the surface of the brain and the pressure of the blood leaving the aneurysm dissects into the brain parenchyma. The pathophysiology of how some of these hemorrhages are isolated, without concurrent subarachnoid hemorrhage is not well understood, but it is hypothesized that adhesion between the aneurysm dome and the brain surface, due to inflammation or prior leakage creates a region where blood can rupture into the parenchyma without involving the subarachnoid space 3.
The same principle has been implicated in isolated subdural hematomas resulting from aneurysmal rupture 5.
Location
The location of the hemorrhage can be useful in predicting the location of the ruptured aneurysm.
-
frontal lobe
- inferomedial (gyrus rectus): ruptured ACOM/A1aneurysm
- inferolateral (frontal operculum): ruptured M1 aneurysm
-
temporal lobe
- pole or temporal operculum: ruptured M1 aneurysm
- medial: rupture PCOM aneurysm
Radiographic features
CT
- elongated hyperdense hematoma in the periphery of the affected lobe
- the hematoma often 'points' to the site of the ruptured aneurysm
- frequently associated regional or diffuse subarachnoid hemorrhage
- may have associated subdural or intraventricular hemorrhage
- the unthrombosed aneurysm may cause a "filling defect" within either the hematoma or adjacent subarachnoid hemorrhage
Differential diagnosis
In addition to aneurysms and other high-flow vascular malformations, the differential includes other causes of intraparenchymal hemorrhages including:
- primary lobar hemorrhage or hypertensive hemorrhage (depending on location)
- underlying tumors (metastases or primary tumors)
- trauma (cerebral contusions)
- venous infarction
- hemorrhagic transformation of an infarct
