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.
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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.
Clinical presentation
The clinical presentation is highly variable, depending on the location and size of the hemorrhage.
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.
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inferomedial (gyrus rectus): ruptured ACOM/A1aneurysm
inferolateral (frontal operculum): ruptured M1 aneurysm
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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
MRI
The appearance of hemorrhage on MRI varies with time and to some degree the size of the hematoma (see aging blood on MRI).
Treatment and prognosis
Management is primarily of the underlying ruptured aneurysm or other vascular malformation. Otherwise, management of the intracerebral hemorrhage itself does not differ for other causes of intracerebral hemorrhage - please see the article on intracerebral hemorrhage for further discussion 7.
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)