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5.3 Conditions Associated with CAVMs
Some specific syndromes can be identified in CAVMs in children and
have now been recognized as the expression of the origins of the cerebral
and facial vasculature: the cerebrofacial arteriovenous metameric syndromes (CAMS) (see Chap.6, this volume). Others include genetically
based disorders. There are thus far no convincing reports of familial
occurrence of CAVM.
CAVMS in HHT children have several specific aspects in angioarchitecture that may distinguish them from the sporadic forms, as discussed
in Chap. 4 of this volume.While the hallmark of the angioarchitecture in
younger HHT patients is fistula communication, venous ectasias, and
their multiplicity, the nidal type of configuration tends to occur in older
children after the age of 5 or 6 years. Nidus types are seen in adolescents
and younger children and microlesions in young adults (Krings et al.
2005b). It is interesting to note that no new lesions have been seen in the
follow-up of these patients, nor have telangiectasias been demonstrated
in the brain or spinal cord despite the name of the disease.
The association of a CAVM and a separate intracranial dural high-flow
AV S is rare but has occurred in two children in our series (Fig. 5.9). The
entity of CAVMs induced by high-flow DAVSs will be discussed later on in
Sect. 5.1.4.5.
Diseases involving collagen abnormalities have been associated with
cerebral AV shunts. Neurofibromatosis-1 (NF1) (Fig. 5.10) and ElhersDanlos syndrome have been reported in patients with CAVM, but the
brain location is not specific and the relationship between these arterial
wall diseases and the advent of an AV shunt phenotype is unclear.
CAVM in young patients can also be associated with other vascular
anomalies such as cavernomas and developmental venous anomalies
(DVAs) (Fig. 5.11). This association is not common and the coexistence of
these entities needs to be carefully assessed with respect to the perceived
cause of symptoms and proposed treatment strategies. For instance, a
CAVM draining into a DVA is likely to be more clinically eloquent,and at
the same time will be associated with a higher risk of treatment-related
complications if the DVA is not preserved for drainage of the adjacent
normal brain (see Chap. 8,this volume).
5Cerebral Arteriovenous Malformations302
303Conditions Associated with CAVMs
Fig. 5.9A–D. A 27-year-old female had become symptomatic at age 13 with dyspnea,
and at that time 15 pulmonary arteriovenous shunts (AVSs) were diagnosed and subsequently treated by embolization. Recent CT investigation for headaches (not
shown) suggested posterior fossa AVM. Lateral views of the external (A) and internal
carotid angiogram (B) demonstrated a dural AVF along the anterior aspect of the
middle cranial fossa (arrows), while the vertebral angiogram in lateral view (C)
demonstrated a small AVM adjacent to the inferior aspect of the fourth ventricle (ar-
row). Examination of the right hand (D) revealed typical changes involving the
nailbeds compatible with longstanding cyanosis as well as a post-traumatic AVS involving the dorsal aspect of the right hand in this patient with proven HHT
5Cerebral Arteriovenous Malformations304
Fig. 5.10A–E. A 13-year-old boy suffering from repeated intracranial hemorrhage resulting in permanent moderate hemiparesis, seizures, and
headaches. Family history was suggestive of NF1 (A–E)
305Conditions Associated with CAVMs
Fig. 5.11A–C. A young adult
presenting with a sudden
intracerebral hemorrhage with
no previous personal history,
resulting in a residual left-sided
hemiplegia. Note the typical
DVA appearance (A,B). Elective
embolization of the fistula was
achieved (C)
5.4 Conditions Mimicking CAVMs
5.4.1 False Pial Arteriovenous Malformations
Including Proliferative Angiopathies
False pial arteriovenous malformations (PAVMs) demonstrate early
venous return associated with some types of nidus appearance.Some are
easy to identify,usually because of the clinical history or in some circumstances because of their angioarchitectural appearance. Some angiogenic
networks may give rise to a hemorrhagic event,and because of their AVM
resemblance, they are referred for endovascular treatment.
5.4.2 Perinidal Angiogenesis
Perinidal angiogenesis can occur is some patients with PAVMs. These
perinidal angiogenic areas may make the nidus appear to be enlarged.
The difficulty is that if an AVM (nidus) develops (see Chaps.2 and 6, this
volume), it expresses the activity of a given growth factor or factors to
achieve an aberrant remodeling program. Since the nidus does not seem
to grow under the same conditions and the same pattern as the secondary
angiogenesis, it suggests that either the growth factors are different or the
receptors have changed or both (Figs. 5.12, 5.13).
5.4.3 Postischemic Luxury Perfusion
Postischemic luxury perfusion occurring in the subacute phase following
cerebral infarction may mimic at angiography the appearance of a diffuse
type of AVM nidus. Clinical presentation and the normal-size feeding
arteries and draining veins will distinguish these two conditions. Conversely, deeply located true AVMs with a small, early draining vein may
sometimes have a similar angiographic appearance as postischemic
luxury perfusion, except that the revealing symptom will usually be a
hemorrhagic episode, which may recur. These ischemic lesions should
obviously not be surgically removed or treated by embolization or radiosurgery.
5.4.4 Proliferative Angiopathy
Proliferative angiopathy also belongs to this group, as it combines a diffuse vascular network with moderately enlarged veins not dissimilar to
what would be seen in a true AVM.Patients usually do not present with an
acute neurological deficit or hemorrhage but more commonly with
epileptic syndromes, headaches, and progressive neurological deficits
(Fig. 5.14).Angiogenesis is confirmed by transdural supply demonstrated
bilaterally,anywhere on the cortex and sometimes infra- and supratentorially. Segmental stenosis of the middle or anterior cerebral arteries can
be seen during follow-up. The angiopathy is often mistaken for moy-
5Cerebral Arteriovenous Malformations306
307Proliferative Angiopathy
Fig. 5.12A–E. A 15-year-old girl presenting with a sudden right hemiplegia due to intracerebral and intraventricular hemorrhage. The first angiographic diagnosis, although not typical, was AVM (A–C). She was treated conservatively; she hemorrhaged
again a few months later (D, E), which corresponded to typical hemorrhagic angiopathy
5Cerebral Arteriovenous Malformations308
Fig. 5.13A–F. Legend see p. 309
amoya disease (Fig. 5.2) when bilateral and the posterior circulation is
spared. However, the pattern of capillary ectasia, the rapid venous filling,
and the type of dural angiogenesis is different. This angiopathy is most
commonly encountered in Caucasian females (3:1).This group is similar
to some of the cases that Chin et al. (1992) described as diffuse nidus
AVMs. In his series,six out of 12 patients were children.This entity will be
seen with the ischemic diseases in Chap. 18.
5.4.5 Induced Pial AV Shunts Secondary to Dural Sinus High-Flow Lesions
The next group includes induced pial AV shunts secondary to dural sinus
high-flow lesions (see Chap.7, this volume). This group is particular, as
these shunts develop over time, usually years,and do not seem to produce
any specific symptoms, despite their obvious progression over time
(Fig. 5.15). Some regress after partial occlusion of the prominent primary shunts on the sinus wall. Their own natural history is not known, but
the persistence of the primary dural shunt seems sufficient to make them
more active and create flow-related arterial aneurysms or induce additional lesions. This actually shows how a lesion that is essentially the
same will eventually appear worse by the induced effect on a previously
normal portion of the vasculature. The secondary occurrence of these
pial shunts shows the efficacy of the venous sump effect in creating these
lesions upstream and involving the cerebral veins.
It seems that the early maturation of the vascular system introduces
the low-pressure regimen of the jugular system. Its role in arterial diastolic flow appearance is likely to be important, as shown by its rapid disappearance during crying or other Valsalva maneuvers in babies. The increase in diastolic fraction in CAVM points to the loss of resistance at the
capillary level, but also suggests the loss of resistance at the venodural
junction; in addition, the loss of normal autoregulation at the shunt site
may later involve additional vasculature. This raises the question of
whether the failure of the venodural junction to establish an early resistance in otherwise normal dural sinuses might not, through the sump effect,trigger the development of certain superficial AVFs that open directly into the superior sagittal sinus. Some of them, although showing highflow characteristics, are amazingly well tolerated and without any cardiac
overload.
309Induced Pial AV Shunts Secondary to Dural Sinus High-Flow Lesions
Fig. 5.13. A, B A 6-year-old boy presented with a sudden left-sided hemiplegia caused
by a ruptured mesencephalie AVM with a cranially located intracerebral hematoma.
Angiography demonstrates the small nidus and what seems to be a false sac annexed
on the single venous drainage (C, D). Six months later, there was evidence of angiogenesis into the previous hematoma,resulting in a slight enlargement of the draining
vein (E, F)
▲
5Cerebral Arteriovenous Malformations310
Fig. 5.14A–E. MRI with coronal (A) and axial (B) views demonstrates typical appearance of abnormal vasculature interspersed
with brain parenchyma involving the left parietal lobe, which
is of slightly increased signal on T2WI during investigation
of a young female with seizure disorder dating from age 15.
Angiography of the left internal carotid artery in lateral (C)
and frontal (D) views demonstrates a proliferative angiopathy
with slow shunting into normal-sized draining veins, while
external carotid angiogram in frontal view (E) shows
transdural supply to the same lesion
5.5 Angioarchitectural Progression of CAVMs in Children
In all AVMs, there are changes that occur in the angioarchitecture of the
lesion as time passes, and this is even more apparent in children. Knowledge and understanding of these changes correlate with the natural
course of the disease and its symptomatology constitutes a guideline to
be used in treatment planning.
Similar to VGAMs, or CAVMs in adults, we link the course of the disease to various angioarchitectural characteristics.
5.5.1 Venous Angiopathy
The abnormalities of the venous system are a prominent feature of childhood AVMs (Scheme 5.1A). They can be very obvious and possibly be related to an acute event. They should always be scrutinized with special
care, as they are the most active part of an AVM. It is probable that all
symptoms before the age of 3 years are venous in origin and it is only
much later that some of the more common types of high-flow angiopathy
of arterial origin are seen.
We have divided the venous features into four main groups that can be
differentiated as distinct problems.
311Ve n o us Angiopathy
Fig. 5.15A,B. An 11-year-old girl who had presented at the age of 2 years with right
proptosis related to an orbital hematoma.Angiography performed at that time failed
to demonstrate any intracranial anomaly. Over a period of 10 years, she developed
progressive right-sided hemiparesis,dysphasia,and ataxia related to a juvenile type of
dural arteriovenous shunt.Although angiography had been normal at the age of 2 at
the intracranial cavity, note the remote pial arteriovenous communications induced
by the lesion. (From Garcia-Monaco et al. 1991c)
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