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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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121Ve in of Galen Aneurysmal Malformation
Fig. 3.11A–D. A 2-month-old
girl presenting with cardiac
overload equilibrated with
medical treatment as well
as macrocrania and already
moderate ventricular dilatation.
She presented with a generalized seizure and a mild motor
deficit.When we saw her at
6months ofage,there was
already a delay in neurological
acquisitions. A, B Angiography
and C, D MRI demonstrates
an explosive transhemispheric
network of vessels reaching
the choroid fissure and opening
into the vein of Galen malformation
The nidus of the lesion is usually located in the midline and therefore
receives a bilateral and symmetrical supply (Fig. 3.17). In certain instances, one side may be more prominent, and this will cause the dilated
pouch to be shifted by the force of the jet of the fistula away from the
prominent supply toward the opposite side (see Fig. 3.42). In general
terms, two types of angioarchitecture are encountered: choroidal and
mural. The former corresponds to a very primitive condition, with the
contribution of all the choroidal arteries and an interposed network
before opening into the large venous pouch (see Figs. 3.12, 3.16). This
condition is encountered in most neonates with low clinical scores
(see Sect. 3.8). The latter corresponds to direct AV fistulas within the
wall of the median vein of the prosencephalon (see Figs. 3.17, 3.39).
These fistulas can be single or (more often) multiple and either converge
into a single venous chamber or into multiple venous lobulations
located along the anterior aspect of the pouch or along the afferent
choroidal veins of the fissure (Fig. 3.11).This mural form is often better
tolerated and encountered in infants who do not develop cardiac
symptoms and who have a better disease tolerance and feature higher
clinical scores. Intermediate forms can occur, but their identification
does not assist in the understanding of the disease, and they are only interesting from a technical and management point of view.So far,we have
not seen a true VGAM associated with another type of AVM.
3Vein of Galen Aneurysmal Malformation122
Fig. 3.12A,B. Two different VGAMs with an interventricular foramen arteriovenous
fistula, associated with a more posteriorly located usual VGAM in a choroidal form
123Ve in of Galen Aneurysmal Malformation
Fig. 3.13A–F. Legend see p. 124
Since the choroidal veins are the embryonic tributaries of the median
vein, potentially fistulous communications can be located at some distance from the pouch (Figs. 3.10, 3.13). They usually occur at the level of
the interventricular foramen, where they can recruit a specific perforating branch (Fig. 3.13) from the anterior communicating artery or the
Heubner artery. Some multifocal AVSs can associate mural communications with an additional shunting zone at the rostral end of the choroid
fissure (Fig. 3.10). In this case, a choroidal venous segment is seen prior to
its opening into the ectatic vein.
The venous drainage of the VGAM is, by definition,toward the dilated
median vein of the prosencephalon,forerunner of the Galen vein,and no
communication exists with the deep venous system of the brain nuclei.In
VGAM patients,thalamostriate veins open into the posterior and inferior
thalamic (diencephalic) veins, as occurs normally during the 3rd month
in utero (Figs. 3.21,3.22).They secondarily join the anterior confluence,a
subtemporal vein,or (more often) the lateral mesencephalic vein to open
into the superior petrosal sinus, demonstrating a typical epsilon shape
on the lateral angiogram (see Figs. 3.23, 3.24). In older children, the
choroidal veins opening into the VGAM may become visible; if restriction
in the skull base outlet has occurred (see Fig. 3.25) subependymal-striate
anastomoses may open and become visible on the venous phase of vertebral angiograms. These can be the cause of intraventricular hemorrhages
following transvenous approaches.
The remainder of the venous drainage is variable, with the straight
sinus being absent in almost all cases. Falcine dural channel(s) drain
the pouch toward the posterior third of the superior sagittal sinus,which
also happens to be where granulations are expected to appear first
(see Chap. 2, this volume). In most cases, restrictions at the venodural
3Vein of Galen Aneurysmal Malformation124
Fig. 3.13A–G. A 3-year-old boy
presented macrocrania at the
age of 4 months.MRI (A,B),
3D angiography in superior (C)
and lateral (D, E) views,demonstrating the recurrent artery
from the ACA-A1 segment
supply an interventricular
foramen AV shunt associated
with a choroidal VGAM (E).
F, G MR follow-up following
embolization of the Heubner
as well as choroidal contributors to the lesions
125Ve in of Galen Aneurysmal Malformation
Fig. 3.14. A A 26-year-old woman with more than 20% mental retardation and
right-sided hemiparesis showing VGAM revealed at the age of 5 months.Note the
subependymal contribution to the anteriorly located shunting zone to the ectatic
vein. B Immediately following embolization,there was still flow inside the lesion.
C After spontaneous secondary thrombosis, the subependymal supply, although not
embolized, regressed spontaneously
3Vein of Galen Aneurysmal Malformation126
Fig. 3.15. Ty p ic al limbic circle
of the archaic type: anterior
choroidal to anterior cerebral
artery in a young girl presenting with a VGAM diagnosed in
infancy with mild macrocrania
Fig. 3.16A,B. Three-dimensional aspect of a persistent limbic arch. A Lateral and
slightly anterior oblique view. B Medial and slightly anterior oblique view. Note the
choroidal and subependymal feeders
127Ve in of Galen Aneurysmal Malformation
Fig. 3.17. A,B Legend see p.128
junction or in the falx create upstream and downstream turbulence and
significant dilatations (Fig. 3.25). Other embryonic sinuses persist, such
as the occipital and marginal sinuses (Fig. 3.26),particularly in neonates.
The appearance of the remainder of the venous system is difficult to predict, even though all cerebral veins converge at birth toward the posterior sinuses. A few months after birth, the cavernous sinus matures and is
able to „capture“ the sylvian veins,offering the brain a potential drainage
through the orbit, pterygoid plexus, or inferior petrosal sinus (Fig. 3.27).
Drainage of the cerebral veins into unusual transcranial channels may
take place, apparently without significant functional implications
(Figs. 3.28,3.29). The plasticity of the venous system in these instances is
remarkable. Although the anatomic framework is exact and predictable,
it is crucial to remember that it changes with spontaneous modification
of the hemodynamics, the influence on growth and maturation induced
by the disease and, eventually, the treatment undertaken. The timing of
interference with this anatomic maturation continuum is as important as
the extent of the corrections proposed.At this age,it is more important to
restore normal growth conditions than a normal appearance, which is
often the therapeutic goal in adults.
Other midline malformations (clefts, sinus pericranii, coarctation)
have been noted in some rare cases, although they rarely correspond to
existing or potential syndromes (Fig. 3.30).
3Vein of Galen Aneurysmal Malformation128
Fig. 3.17. A An infant girl presented with macrocrania at the
age of 6 months leading to the
diagnosis of a large VGAM. She
was referred at the age of
8months.There is a posterior
cerebral to anterior cerebral
limbic system with a midline
fusion phenomenon of the anterior cerebral artery.B Following embolization of the main
feeders and despite persistence
of minimal shunt at the end of
the second embolization,spontaneous thrombosis occurred
concomitantly with (C) the
maturation of the limbic circle
and shrinkage of the mass
129Ve in of Galen Aneurysmal Malformation
Fig. 3.18. A, B Persisting limbic arch immediately after embolization.C–F Uni lateral remodeling of the supply to the paracentral gyrus after completion of the VGAM occlusion
3Vein of Galen Aneurysmal Malformation130
Fig. 3.19A–F. A 13-year-old boy presented at the age of 5 years with macrocrania.
Subcallosal anastomosis between right and left posterior cerebral arteries (PCAs)
(A, B) is likely to correspond to an asymmetrical maturation of the limbic circle. Note
the right A1 agenesis (C),and P2 on the left (D). Bilateral distribution of the left anterior cerebral artery (ACA) (E, F). These features point to the capacity of midline
fusion in the limbic system as well as ACA remnants
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