also known as "Developmental venous anomalies" (DVAs) to
emphasize their frequency and their benign nature and low
incidence of sequelae. They are the most common vascular
malformation found at postmortem.
are most commonly located in the following descending order of
frequency frontal lobe, parietal lobe, and cerebellar hemisphere.
They may also be found in the region of the vein of Galen
are sporadic in nature with no genetic predisposition
occur due to arrest of normal venous development with retention of
primitive medullary veins draining blood into a large anomalous
draining vein is the presumed etiology
are mostly seen as a small single lesion of low flow and low
pressure. They represent the venous drainage of the area. There
anomalous venous drainage of
normal brain tissue. It consists of radially arranged anomalous
medullary veins that converge on a larger central draining vein
that, in turn, drains into deep or superficial venous system.
"crown" of veins that converge onto the connecting trunk
are "collecting veins" that drain the capillaries from the
veins are slightly thickened and hyalinized with large amounts of
smooth muscle and elastic tissue. Venous radicles are separated by
normal/ gliotic intervening brain tissue.
abnormal arteries are found. They may be associated with a cavernous
angioma in 20%.
are most commonly detected incidentally. However they may present
with headache and focal deficit. Seizures occur rarely and may be
due to chronic ischemia, encephalomalacia and calcification .
in a venous angioma is seen less commonly than seizures.
however, may be more frequent in those venous angiomas with
concurrent stenosis of the draining vein and or concurrent cavernous
angioma. Even in these cases the bleed is mostly at the sites of the
cavernoma and not the venous angioma
contrast scan is normal unless there is calcification or acute
enhanced scan reveals a tuft of small vessels draining into a
dilated, subependymal or subpial vein may be seen with contrast.
reveals transmedullary flow voids or as paired transmedullary lines
of increased and decreased signal representing spatial
misregistration of the vessel wall and lumen because of the Doppler
shift in frequency associated with flow. The draining trunks are
substantially larger than adjacent veins, perhaps because they
serve as collateral drainage pathways for adjacent regions in which
veins failed to develop (or later thrombose).
enhancement improves display of slow flow and may be required to
detect venous angiomas not otherwise seen. It reveals the
characteristic medusa head draining into a larger vein.
of the large central vein as it enters the dural sinus and
concurrent cavernous angiomas must be sought out and described, if
possible, since they may signify increased risk of bleeding.
may be angiographically occult, however, they classically produce
distinct caput medusae (other descriptive terms include: a hydra,
spokes of a wheel, a spider, an umbrella, a mushroom or a starburst
pattern or "medusa head")
really looks more like a hydra or a palm tree - the dominant
transcortical vein is the trunk; and the radiating crowns of feeding
veins are the leaves.
of the following reasons Rx is rarely indicated.
is reserved for the following situations
Intractable seizures attributed to the lesion
is still debatable. It is not accessible via an endovascular
unless there is associated venous stenosis or cavernoma
lesions consist of groups of abnormally swollen capillaries and
usually measure less than an inch in diameter. Capillaries are the
smallest of all blood vessels, with diameters smaller than that of a
human hair; they have the capacity to transport only small
quantities of blood, and blood flows through these vessels very
slowly. Because of these factors, telangiectases rarely cause
extensive damage to surrounding brain or spinal cord tissues. Any
isolated hemorrhages that occur are microscopic in size. Thus, the
lesions are usually benign. However, in some inherited disorders in
which people develop large numbers of these lesions, telangiectases
can contribute to the development of nonspecific neurological
symptoms such as headaches or seizures
claim that angiograpically occult venous malformation (AOVM)
is a heterogenous group of malformations (AVMs, cavernomas
and others) that are not detected by angiography and diagnosed by CT
or MRI. They do not group them with the Capillary telangiectasis and
Cryptic AVMs, which are a separate histopathological entity,
encountered during haematoma evacuation. For all practical purposes
they are considered as one group by most. Surgical intervention is
indicated only when there is a large haematoma, requiring