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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3644_Библиотеки_им_академика_М_И_Перельмана
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malformations,the latter hemangiomatous lesions.In fact,such a distinction,which was helpful during the past 20 years, has also greatly benefited from recent biological contributions as well as the recognition of shear
stress mechanisms in vascular modeling and remodeling.Actually angiogenesis is involved in both so-called malformations and hemangiomas,
but they are different in terms of trigger factor (agent),target, and timing
(Schemes 2.1,2.2).They will be discussed in the various chapters dealing
with brain and maxillofacial AVMs and hemangiomas.
2.3 Vascular Lesion Types and Disease Groups
Many and often confusing classifications have been proposed in the past.
The role of coagulation disorders, systemic manifestations, topography,
size, eloquence of the involved brain, and extrapolation from experience
with adult lesions has led to emphasis being placed on many different
aspects, which, in combination with technical advances, tended to focus
on certain particular details rather than on an understanding of the
problem as a whole. The assumption that AVMs are congenital, the rarity
of the disease, the small number of patients in the clinical series reported, and the aggregation of various pathologies described in literature
reviews further added to this confusion (Govaert 1993; Raimondi 1980;
Edwards and Hoffman 1989).
Basic classifications of vascular diseases use pathological, biological,
and clinical data. For instance, one should now be able to distinguish AV
shunts from venous lesions or malformations.Furthermore one should be
able to recognize and differentiate venous variations from malformations.
Similarly, one should not label an associated arterial variation or embryonic persistence a malformation when associated with a CAVM or a giant
aneurysm. This distinction is not only of academic interest, but may also
have clinical consequences.A true malformation is not an anatomic variant,and the isolated persistence of an embryonic disposition does not give
a congenital character to a lesion even if in some cases it is a time marker
of an embryonic event,which may not necessarily be related.
When considering vascular lesions in children,one should keep in mind
several keys to approaching the questions raised and understanding the
clinical expression (phenotypes) of the various diseases involved. Even in
an apparently single-disease category such as CAVMs, several entities must
be distinguished as their predictable presentation or progression requires
different management at different times. The generic name artificially regrouping different situations expresses the use of a single key (the arteriovenous shunt for example) where two or three would reveal the differences: single hole AVF (Yoshida 2004; Weon et al. 2005), familial disorder
for HHT (Mahadevan 2004),metameric disease for CAMS (Bhattacharya et
al. 2001), proliferative activity for proliferative angiopathy, PHACE (Bhattacharya et al. 2004),etc.
31Vascular Lesion Types and Disease Groups
2Introduction and General Comments Regarding Pediatric Intracranial Arteriovenous Shunts32
Ta ble 2.1a. Vascular diseases, genetics: karyotypes
Disease
a
Chromosome location
HHT
b
Ch 9q33–34 endoglin
Ch 12q Alk 1
Cavernomas Ch 7q21–22 CCM1
(KRIT1 is the mutated protein CCM1)
Ch 7p13–15 (CCM2)
Ch 3q25,2–27 (CCM3)
MCMVM: BRBN (Bean syndrome) Ch 9p Tie 2/Ch1 cutaneous
ED IV Chromosome 2
NF1 Ch 17q22
NF2 Chromosome 22
VHL Ch 3p25–26
Moyamoya Ch 17q25
Ch 3p24.2-p26
Bourneville TSC1 Ch 9q34
TSC2 Ch 16p13
CADASIL Ch 19q
FHM Ch 19
Paragangliomas 11q23
Polycystic kidney disease Ch 16p13.3 (PDK1)
Ch 4 (PDK2)
a
The same effects are expected to follow functional blockade of a gene rather than
single type of structural alteration in each patient: when the gene involves
interactions (ligand), the mutations are multiple; when the gene makes a protein
active, the mutations are often identical: lack of stage (protein or mRNA is missing),
poor emission of signal or wrong destination (pigmentation), no reception of signal
(ligand), insufficient message (too short, too few), hyperactive protein.
b
Each family has its own mutation >100.
Ta ble 2.1b. Vascular diseases, genetics: angiogenic activity
Arterial angiogenesis Venous angiogenesis
VHL HHT
NF1 BRBN
Moyamoya Cavernomas
PHACE CVMS
Proliferative angiopathy
CAMS
Primary arterial angiectasia
a
Primary venous angiectasia
a
Aneurysms DSM
DVAs
Ve n o us angiogenesis
Ly mph at ic angiogenesis
LM
a
Not flow-induced.
33Vascular Lesion Types and Disease Groups
Scheme 2.3. Timing of triggering events and phenotypic expressions
Scheme 2.4A. „Age“ of vascular lesions
The following keys can be put forward:
Proliferative or nonproliferative lesion
Ty pe of disorder (Table2.1):
– Monogenetic (surface protein dysfunction, improper collagen
structure, extracellular matrix deficiency), progressive dysfunction
(triggered structural defect or failed repair or inadequate maintenance systems), extrinsic and acquired damage (infectious, traumatic) (Scheme 2.1)
Location on the vessel tree:
– From the arterial tree to the arterial capillary, venous junction
venules, veins,sinuses,and lymphatics (Scheme 2.2)
Time of occurrence:
–Germinal mutation transmitted, early somatic mutation,early stage
metamerically arranged defect, fetal failed signaling, postnatal
mutation, failed remodeling during vascular renewal (Scheme 2.3)
Time of revelation:
– In utero, fetal period, neonatal, infancy prior to 2 years of age,
2–6 years,and after 6 years (Scheme2.4)
Clinical evolution and natural history:
– Permanent increase in flow, arterial occlusion, spontaneous throm-
bosis (see Chap. 7,this volume).
Secondary effects on the maturing or remaining vasculature:
High-flow angiopathy, jugular bulb maturation, cerebral vein opening
into the cavernous sinus, pacchionian granulations development (see
Chaps. 3,5, this volume).
2.3.1 Nonproliferative Lesions
2.3.1.1 Arteriovenous Lesions
The AV lesions that can be encountered depend on the meningeal space
from which they primarily develop: dural, pial, subarachnoid, or
choroidal (Scheme 2.5).These locations give rise to several subtypes and
may be unifocal, multifocal, hereditary,etc. (Scheme2.6).
2Introduction and General Comments Regarding Pediatric Intracranial Arteriovenous Shunts34
Scheme 2.4B. So-called congenital or malformative vs acquired neurovascular lesions
2.3.1.2 Isolated Brain AVMs
These can be small (micro-AVM; see Fig. 2.1) or large (macro-AVM;
Fig. 2.2), and this distinction is of nosological interest, as the passage
from one type to the other cannot be demonstrated.Of interest is the distinction between the nidus type (with an arteriolar network; Fig. 2.1) and
the fistulous type (single or multiple large, direct AV communication; see
Fig. 2.3). The former consists of a group of small AV shunts within a vascular meshwork within the nidus,while the latter is a direct opening of an
artery or arteries into an unusually enlarged or giant draining vein, with
or without outflow restriction. This distinction is a significant one, and in
our opinion similar to what was said for micro- and macro-AVMs, there
35Isolated Brain AVMs
Scheme 2.5. Spaces hosting
intracranial ateriovenous (AV )
shunts.VGAM, vein of Galen
aneurysmal malformation;
AVM, arteriovenous
malformation
Scheme 2.6. Subtypes of vascular lesions in children. AVM, arteriovenous malformation
Pial AV Shunt in Children
Micro/Macro AVM
Micro/Macro AVF
Multifocal
CAMS
Familial
Proliferative angiopathy
Hemorrhagic angiopathy
Fal se and induced AV shunts
is no transition from AVMs to AVFs or vice-versa. CAVMs can occur in
the subpial space,where they can be superficial or deep,corticoventricular, or buried in the white matter; in this latter location they should be
distinguished from hemorrhagic angiopathy (see below and Chap. 18,
this volume) (Fig. 2.4). From their origin onwards, they contain no neurons or nerve fibers within their nidus, which had led some authors to
describe pial AVM (PAVM) as extracerebral. This justifies the distinction
of proliferative angiopathy as a distinct group of diseases (see below and
Chap. 18, this volume).Fistulas are also subpial; they drain either immediately into subarachnoid vein(s) or within the subpial venous network.
They are superficial at the cerebral cortex or the surface of the cord.They
are not supplied by ventral longitudinal neural perforators.
2Introduction and General Comments Regarding Pediatric Intracranial Arteriovenous Shunts36
Fig. 2.1A,B. Ty pi cal aspect of a cortical micro-AVM revealed by an intralobar
hematoma in a young boy
Fig. 2.2A,B. Medium-sized deep-seated AVM discovered incidentally in a young boy.
Both lesions were treated successfully by embolization
37Isolated Brain AVMs
Fig. 2.3. A, B A 7-day-old child presented with cardiac failure, for which a cerebral
arteriovenous fistula (AVF) was diagnosed. There was a family history suggestive of
HHT.The AVF was embolized at the age of 3 years.There was no focal melt in relation
to the direct subarachnoid vein opening of this cortical fistula. C The child is neurologically normal at 12 years of age, the lesion is partially excluded, and there is no
evidence of melting-brain syndrome
Fig. 2.4. A 5-year-old boy presenting with hemianopia in relation to a subcortical hemorrhage. B, C Angiography demonstrates a hemorrhagic angiopathy. D, E One year
after radiation therapy,the lesion is no longer visible
2Introduction and General Comments Regarding Pediatric Intracranial Arteriovenous Shunts38
Fig. 2.5. A A male infant presented with macrocrania with vein of Galen aneurysmal
malformation (VGAM) of the mural type. Untreated cardiac overload was also noted
at that time. He was referred to us at the age of 3 years following an episode of generalized seizure.B Almost complete occlusion was obtained in one session. C,D A small
remaining shunt was seen 2 years later (arrow,remaining venous drainage) and final
spontaneous disappearance was verified.At the age of 8 years,the child’s score was 4
and he was not taking any antiepileptic medication
2.3.1.3 CAVFs
We have treated cerebral arteriovenous fistulas in children in a separate
chapter since they raise specific nosological clinical and therapeutic challenges (Yoshida et al. 2004; Weon et al. 2005). Their linkage with hereditary hemorrhagic telangiectasia is remarkable (see Chap. 4, this volume)
(Mahadevan 2004). Drainage into subpial or subarachnoid veins is of
paramount importance in this topography, particularly in neonates and
infants (Fig. 2.3; see Sects.2.4.2 and 2.4.3). Finally, there is no gender
dominance in CAVM in children (see Chap. 5, this volume)
2.3.1.4 VGAMs
VGAM is a unique, well-defined group of malformations that occur at the
end of the embryonic period (Fig. 2.5). They constitute a separate group
from other lesions such as CAVMs, and they are often called non-Galenvein AV malformations,particularly in neonates and infants.In the VGAM
group, there is a 2–3:1 male predominance (see Chap.3, this volume).
2.3.1.5 Cerebrofacial Arteriovenous Metameric Syndromes
The diagnosis of cerebrofacial arteriovenous metameric syndromes
(CAMS) (Chap. 6, this volume) encompasses a spectrum of phenotypic
expressions. Features of the syndrome as originally described and common to all cases include arteriovenous malformations of the brain and
orbit (with retinal and/or retrobulbar lesions) (Bonnet-Dechaume-Blanc
or Wyburn-Mason syndrome) and maxillofacial lesions. A portion of
these patients will manifest the complete expression of the disease with
additional high-flow arteriovenous malformations of the maxilla or
39Cerebrofacial Arteriovenous Metameric Syndromes
Fig. 2.6. Cerebrofacial vascular
metameric syndromes. Three
territories linking the brain
to the face can be recognized.
Depending upon the type of
cell involved,arteriovenous
(CAMS 1–3) or venolymphatic
(CVMS 1–3) metameric
syndromes are involved.
At the first cervical segment,
SAMS 1 (green arrow)
(SAMS 1–31) is represented.
(From Bhattacharya 2001)
Galenic Vascular Lesions
in Children
Choroidal VGAM
Mural VGAM
VGAD
Dural VGAV shunt
Venous dilatation
mandibular regions. These represent distinct and additional life-threatening risks because of epistaxis or oral hemorrhage. We have suggested
segmental patterns of involvement in what is likely to be a disease of the
neural crest and/or adjacent cephalic mesoderm. A newly proposed rational classification reflects the putative,underlying disorder and calls for a
new label: cerebrofacial arteriovenous metameric syndrome (CAMS)
(Bhattacharya et al. 2001) (see Chap. 6) (Fig. 2.6). The various lesions associated with CAMS may reveal themselves over time in a consecutive
fashion suggesting pseudo de novo lesions (Fig. 2.7).
2Introduction and General Comments Regarding Pediatric Intracranial Arteriovenous Shunts40
Fig. 2.7A–C. CAMS 2.A 4-yearold boy presented with a retinal
AVM. A At that time, MR was
normal. B,C Six years later,
a diencephalic lesion associated
with the previous lesion can
be seen
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