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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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vasculogenesis, involves differentiation and sprouting of mesodermderived endothelial cells to form the primitive capillary network,
which is then extended and remodeled by angiogenesis (Le Douarin
et al. 1997).These primary capillary vessels become progressively ensheathed by differentiating smooth muscle cells.It is now recognized
that while head and neck endothelial cells, as elsewhere, derive from
mesoderm, the tunica media of these vessels differentiates from neural crest cells (NCCs) (Risau 1997), which stream into the developing
head and pharyngeal arches. Hox gene-encoded positional information in the crest cells is known to be involved in patterning of the pharyngeal arches and is most likely involved in determining NCC distribution among the arch-derived arteries as well. The work of Couly
and Le Douarin has further shown that the neural crest and mesodermal cells originating from a given transverse (metameric) level of the
embryo finally occupy the same territory in the head, and that these
embryonic tissues are regionalized in various areas devoted to providing blood vessels to specific regions of the face and brain (Couly et
al. 1995),(Etchevers et al 2001).
Fate maps of the cells occupying these regions of the neural plate,
crest, and cephalic mesoderm, in these avian experiments, reveals
striking similarities to the distribution of lesions encountered in the
human Wyburn-Mason syndrome: for example, the region of the anterior lip of the neural plate contains the anlage of the hypothalamus
(closely related to the adenohypophysis) and the skin of the future
nasal region. Similarly, ablation experiments of the anterior
rhombencephalic neural crest are associated with absence of development of the mandible.
A somatic mutation developing in the region of the neural crest or adjacent cephalic mesoderm prior to migration could be expected to produce
malformations with a segmental distribution in a similar fashion to
Cobb’s syndrome in the spine (metameric AVMs of the spinal cord and
cutaneous involvement of the related dermatome: SAMS (see Vol. 2,
Chaps. 11 and 15,this volume).
We have proposed the name cerebrofacial arteriovenous metameric
syndrome (CAMS) for this condition (Bhattacharya et al.2001).We identified subgroups of patients within a spectrum of segmental craniofacial
AVMs (Table 6.1). This disease spectrum finds its origin related to the
neurosensorial placodes, as schematically illustrated in Fig. 6.3.
CAMS 1: A midline prosencephalic (olfactory) group with involvement
of hypothalamus (hypophysis) and nose (Fig. 6.4).
CAMS 2: A lateral prosencephalic (optic) group with involvement of
optic nerve, retina, parietal temporal occipital lobes, thalamus, and
maxilla (Fig. 6.5).
The mesencephalic crest does not appear to reach facial expression and
lesions here would not be expected to result in a cerebrofacial syndrome.
CAMS 3: A rhombencephalic (otic) group, with involvement of cere-
bellum,pons, petrous bone, and mandible (Fig. 6.6).
6Cerebrofacial Arteriovenous Metameric Syndrome362
A more extensive insult would be expected to overlap territories, producing a complete prosencephalic phenotype (CAMS 1+2) (Fig. 6.7) or bilateral involvement (CAMS 2) (Fig. 6.8). Of course, the disease spectrum
could be incomplete,either because some cells are spared or because they
have not been triggered to reveal the disease. The insult producing the
underlying lesion would have to develop before the migration occurs and
thus before the 4th week of development. This supports the concept that
sporadic brain AVMs could have a similar early initiating cause, but
which may not be morphologically revealed for several years (Lasjaunias
1997).
363Introduction
Ta ble 6.1. Proposed scheme of transitory topographic distribution of vascular lesions in CAMS 1–2, CAMS 3,and SAMS
1–31 (Wong et al.2003)
Metameric Type / CAMS 1, 2 CAMS 3 SAMS 1–31
Te r r i t o r i e s involved
CNS AVMs S/pial +++
S/arach – + +
Only Ist and IInd nerves are At least VIIIth nerve Radicular nerves
involved, but they are subpial
PNS – + +
If Ist and IInd nerve are At least VIIIth nerve Spinal nerves
excluded
Dura – – –
Bone + + +
Nose,maxillae, ethmoid, Mandible, petrous and Vertebrae and ribs
and sphenoid basiocciput
Muscles + + +
Skin + + +
CNS, central nervous system; PNS, peripheral nervous system; S/arach, subarachnoid compartment; –, not present; +,
present.
Fig. 6.3. Schematic representation of the cerebrofacial
arteriovenous metameric
syndromes (CAMS). (From
Bhattacharya et al. 2001).
The proposed metameric
disease groups (CAMS 1–3)
are shown by their main areas
of involvement. Note also
from the drawing that the upper cervical Cobb syndrome
simply represents the caudal
extension of the same disease
spectrum: SAMS (spinal
arteriovenous metameric
syndrome) 1
6Cerebrofacial Arteriovenous Metameric Syndrome364
Fig. 6.4. A CAMS 1. This 49-year-old man was admitted to his referring hospital with
severe epistaxis.He had been noted at birth to have an angioma of the nose,which had
enlarged gradually in recent years (B).He was otherwise well, with normal vision and
retinoscopy.He was referred for embolization of this lesion. External carotid angiography demonstrated a midline nasal and alar AVM (C) fed by both facial arteries.
Internal carotid angiography revealed an additional AVM of the floor of the third
ventricle involving the optic chiasm and hypothalamus (D, E)
365Introduction
Fig. 6.5A–D. A 12-year-old boy presented with headaches and sensitive seizures in
the left superior limb treated by Depakine. He suffered from a right amblyopia associated with slight exophthalmos and retinal vascular malformation. Progressively,
a left hemiparesis and quadranopsia appeared. CT, MRI, and angiography (A, B)
revealed a CAMS 2 with three locations: opticoretinal, thalamostriate,and calcarine.
The child was embolized in 1987 and following the procedure he did not suffer any
headaches and recovered from his hemiparesis.After 1 year,however,the symptomatology recurred but no further endovascular treatment was proposed because of poor
access to the lesion
6Cerebrofacial Arteriovenous Metameric Syndrome366
Fig. 6.6A–E. Legend see p. 367
367Introduction
Fig. 6.6A–H. A CAMS 3. A young girl presenting with mild oral bleedings in relation
with a loose tooth overlying a mandibular AVM (B, C). As a systematic screening,the
angiogram (D–F) revealed the posterior fossa-associated lesion.Note on the MRI the
involvement of the brain tissue as well as the subarachnoid space and temporal bone
(G, H)
▲
6Cerebrofacial Arteriovenous Metameric Syndrome368
Fig. 6.7A–D. CAMS 1, 2
(A). This 28-year-old
man was originally
found to have a retinal
arteriovenous at the
age of 7 years.CT and
MRI studies reportedly
showed an arteriovenous malformation involving the left optic
nerve, chiasm,and
thalamus.A diagnosis
was made of a retinocephalic vascular malformation syndrome:
Wy bur n-Mason or
Bonnet-DechaumeBlanc. In 1990,he
noticed a small red spot
on the tip of his nose,
which was diagnosed
as an angioma (B).
Cerebral angiography
delineated the elongated AVM nidus in
the midline (C, D).
E–G see p. 369
369Introduction
Fig. 6.7E–G. (continued) Injections of the external carotid arteries
show two AVMs: one involving the palate and the other the nose,fed
by branches of the maxillary and facial arteries (E,F).In addition, a
large aneurysm is present at the terminal internal maxillary artery
and two further aneurysms cluster together in the facial artery in
the submandibular region.Embolization of the nasal lesion prior
to plastic surgery was done (G)
6Cerebrofacial Arteriovenous Metameric Syndrome370
Fig. 6.8A–E. Bilateral CAMS 2 (A).An 8-year-old boy
presenting high facial edema with venous dilatation and
proptosis. Right-sided deafness and decrease in visual
acuity of the right eye. A few months before,progressive
appearance of right-sided hemiparesis. MRI (B) and
angiography (C–E) demonstrate typical CAMS 2 type
of arteriovenous malformation. Note the typical aspect
of the lesion on the right side and the small size of the
early draining veins.In addition, there is an usual
bilateral thalamic location. It should be noted that
despite the extension of the apparent nidus,the symptoms were moderate
In the series of Willinsky et al. (1990a) of 213 patients with multifocal
vascular malformations,there was a single CAMS case, while in the Scottish Intracranial Vascular Malformations Study, a true population-based
epidemiological study,in the first 2 years, only one case among 100 brain
AVMs was encountered (Bhattacharya,unpublished data).
Bhattacharya et al. (2001) reported a series of 15 cases. There were
eight male and seven female patients. The age range at presentation was
4–49 years (mean age, 18 years) and 11 of the 15 were 16 years of age or
under.The age of presentation of these patients is clearly much younger
than is seen with sporadic AVMs.As an aid to diagnosis,we divide the potential areas of involvement into three axial zones (brain,orbit, and face)
and propose the criteria that lesions must be present in at least two of
these zones for the diagnosis to be made and then the craniocaudal type
of CAMS established.
All but one of the 15 patients had orbital involvement, while a cutaneous discoloration was only recorded in four cases. Thus the most
frequent patterns of involvement were optic nerve (13/15), retina
(11/15), thalamus (9/15), and chiasm/hypothalamus (9/15). In our
series, there was no definite involvement of the midbrain, and it is
possible that previous reports such as Wyburn-Mason’s confused
prominent mesencephalic draining veins for nidus, suggesting that
this was a common site of involvement. Indeed, the nidus concept of
AVMs was not recognized until 1971, and then initially only in spinal
cord lesions (Doppman 1971). There were also no cases of cerebellar
involvement.
Ty pical features of CAMS 2 (Wyburn-Mason or Bonnet-Dechaume-Blanc
syndrome), are the association of a high-flow arteriovenous malformation of the face with retinal and brain AVMs.In its most complete prosencephalic form (CAMS 1, 2),AVMs can extend forward,continuously,from
the occipital lobes and thalamus via the hypothalamus,optic chiasm,and
optic nerve to the retina; however, they seem to spare the sphenoid and
ethmoid bones (Fig. 6.5).
Previous reports have described a range of abnormalities from this
phenotypic spectrum, mostly stressing the unilateral cerebral involvement. In CAMS 2, bilateral orbital involvement is rare (Kim et al.1998a).
Retinal involvement is also not universal (Brown et al. 1973).Theron et al.
(1974) found that among 25 cases (including their three new ones), four
with retinal lesions had no clinical evidence at presentation of a cerebral
AVM, and the extent of facial involvement was not always apparent clinically. Retinal AVM is often the earliest manifestation of a CAMS 2
(Fig. 6.9), and in two cases,follow-up showed secondary expression of the
syndrome 6years later,while the full extent of the spectrum was revealed
over a 28-year period in another case (Fig. 6.7) (Jiarakongmun et al.
2002).Anticipation of the other locations can be discussed when isolated
retinal, hypothalamic, or optic nerve AVM is diagnosed (Fig. 6.10). However, it is intriguing to note that vision tends to be preserved for a long
time despite extensive involvement of the visual pathways.
371Introduction
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