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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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151Cardiac Manifestations
Fig. 3.36A–D. Prenatal diagnosis at 33 weeks of VGAM.
A At day 1,there was rapid
congestive cardiac failure,
requiring intubation and
assisted ventilation,moderate
hepatic insufficiency, and normal renal function. B,C CT
shows a normal brain. The
neonatal score is 12.D The baby
was therefore embolized as an
emergency procedure on day 7.
Subsequently, the child was
extubated and the cardiac
medication was significantly
decreased.VGAM was completely excluded in a second
session, and cardiac medication
discontinued.At 9 months,
complete occlusion was
confirmed and the child’s score
was 4
3.10 Macrocrania and Hydrocephalus
As opposed to CCF, hydrodynamic disorders can manifest themselves in
fetuses, neonates, and infants (Scheme 3.1C).Choroidal and mural types
almost equally give rise to these types of manifestations. They constitute
the primary revealing factor at infant age if the diagnosis has not been
made previously. They result from the abnormal hemodynamic conditions present at the torcular venous sinus confluence, the posterior convergence of the venous drainage of the brain, and the immaturity of the
granulation system.For many years,and even now, the mechanical compression of the mesencephalic aqueduct was and is sometimes still considered to be the primary cause of the hydrodynamic disorders at this
age. Actually, the aqueduct is patent in almost cases (Diebler et al. 1981;
Zerah et al. 1992). Macrocrania,while resulting in an increasing head circumference, is associated with slightly enlarged ventricles and generous
perivascular spaces (see Figs. 3.37, 3.38).The water dysfunction combines
an intracerebral (intrinsic) retention with an increase in the cerebrospinal fluid (CSF) (extrinsic) volume. Both phenomena have little or
no effect on the brain itself as long as the sutures enlarge,since they tend
to continually adapt to intracranial pressure vs the resistance by the cranial vault.On the other hand,in VGAM in infants the lack of macrocrania
is even more worrisome than its presence. The cerebrofugal medullary
veins constitute a gradient that will induce absorption of most of the
intracerebral water. If the sutures stop growing or if the medullary vein
3Vein of Galen Aneurysmal Malformation152
Scheme 3.1C. Hydrodynamic disorders
resorption decreases (or the pial vein pressure increases), or if for any
other unknown reason the compliance of the venous system fails, hydrocephalus and intracranial hypertension occur.
At infant age, persistence of the situation leads to clinical manifestations, e.g., irritability, alteration of the level of consciousness and neurological status, stagnation of the head circumference, a decrease in brain
volume with enlargement of fluid spaces, and developmental delay. This
means that, before ventricular enlargement occurs, intracranial pressure
is not as high because of macrocrania, and therefore ventricular shunting
153Macrocrania and Hydrocephalus
Fig. 3.37A,B. Yo ung girl with VGAM diagnosed at 2months due to macrocrania.The
child was shunted,but the surgical diversion was unsuccessful.The child was referred
at the age of 8 months with mild mental retardation. Complete occlusion was obtained in three sessions over 2years. C, D Final MRI after occlusion of the VGAM
shows complete shrinkage of the mass and absence of subependymal atrophy,despite
the earlier (nonfunctioning) ventricular shunting
is not indicated. Spontaneous stabilization of the enlarging head phenomena can occur with the cavernous sinus capture of the sylvian veins.
A new low-pressure venous system offers an alternative pathway for water resorption and therefore improves the excessive hydration status of
the cerebral tissue. The progression from macrocrania to hydrocephalus
is therefore not inevitable.
Ve ntricular shunting has long been performed and, while conceptually simple, does require special skill to ensure safe results (Fig. 3.39). Ventricular shunting in VGAM, however, carries an additional risk of morbidity (Fig. 3.40).
As early as 1987, in their review of the literature from 1950 to 1985,
Johnston et al. noted that, of 11 shunted infants (aged 1 month to 1 year),
seven died and only one had no deficit. In an additional group of six
shunted children (aged 1–5years), only two had no deficit.In 1992, in the
series of Zerah et al. (1984–1991), only one out of 17 infants (aged
1month to 2years) underwent an uneventful shunting procedure. The
others had enlargement of the VGAM (n=7; Fig. 3.41), persistent seizures
(n=3), subdural hematomas (n=6; Fig. 3.40),mechanical problems (n=3),
slit ventricles (n=1; Fig. 3.42); none of the patients died. In VGAMs, the
venous pressure is consistently increased and is often very high. Quisling
(1989) reported that pressures were always above 30 cc H
2
O and, in an-
other publication in 1986,pressures were above 50 cc H
2
O with a 1:5 ratio
between intraventricular pressure (IVP) and superior sagittal sinus pressure (SSSP). The increased SSSP dramatically falls to almost 0 after successful embolization. The IVP to SSSP ratio explains why it is so difficult
for the CSF to pass from the subarachnoid space into the dural sinus compartment.
3Vein of Galen Aneurysmal Malformation154
Fig. 3.38. A Girl with macrocrania, with typical VGAM
curve and her response
following transarterial
embolization (E)
155Macrocrania and Hydrocephalus
Fig. 3.39A–D. Female infant (A, B) with VGAM of the mural type diagnosed at
6months with macrocrania. C, D In view of rapidly progressing hydrocephalus, the
child was referred and embolized as an emergency procedure at 9months.
E–G see p.156
Ve ntricular shunting does not deal with the problem created by the
hydrodynamic disorders at the macrocrania phase, but only transiently
and incompletely resolves an emergency situation at the ventricular
level. It creates a cerebropetal flow along the medullary veins opposite to
the natural and necessary cerebrofugal flow. The deficits, seizures, or
hemorrhages seen following ventricular shunting have been so well
accepted that they have even been considered as part of the natural history of VGAM. Endovascular management of the same situations today has
shown that, even with a partial treatment of the AV shunt,these secondary
symptoms do not occur unless additional factors intervene to change the
angioarchitecture of the lesion (see Sect. 3.15).At the infant stage,careful
monitoring of the development of macrocrania is recommended until the
moment of endovascular treatment (at the latest at 5 months).
If the increase in head circumference appears to be too rapid, or if
there is preclinical MRI evidence of intraventricular hyperpressure, or if
the clinical follow-up demonstrates a significant developmental delay,
then urgent embolization should be carried out and ventricular shunting
3Vein of Galen Aneurysmal Malformation156
Fig. 3.39. (continued)
E, F Complete occlusion was
obtained at 1 year. G Four
years later,shrinkage is
complete. Note the mild
subependymal atrophy.
avoided. The rapid deflation (reversal of overhydration) of the brain tissue after embolization is quite characteristic of the hydropic nature of the
disorder (Fig. 3.37). In addition, cessation of the head circumference
increase indicates the permanence of the result obtained.
If the child, on the other hand, is referred too late with increased intracranial pressure that is already clinically detectable in addition to ventricular enlargement, embolization should be carried out first as an
emergency procedure; however, clinical improvement will usually be insufficient even if the hemodynamic result proves to be spectacular, and a
surgical ventricular drainage procedure (ventriculostomy or derivation)
may have to be performed (Fig. 3.38).With this treatment sequence, the
morbidity rate from the shunting procedure is lower. In our experience,
following additional embolization and clamp testing, the ventricular
drainage can often be removed in a few months. The reversed strategy,
shunting first and then embolization,is the worst one for the child unless
endovascular treatment is not available.Today endoscopic ventriculostomy seems to offer an acceptable alternative to the ventricular drainage
after embolization in patients with already symptomatic hydrodynamic
disorders if the base of the brain arteries and veins are not significantly
enlarged at the level of the surgical opening.The overall stagnation at the
mesencephalic aqueduct level observed on flow MRI sequences and the
transfer to the cerebral ventricles with water congestion is then bypassed
and it is likely to offer the skull base and spinal cord alternative resorption possibilities until the granulations mature. The morbidity of ventriculostomy is significantly lower than that of ventricular shunting.
157Macrocrania and Hydrocephalus
Fig. 3.40A,B. This young boy was diagnosed on day 16 with macrocrania and was
then shunted; note the bilateral subdural sequelae following multiple ventricular
shunting. He had severe mental retardation, multiple seizures, and motor deficit. At
age 10, he was referred and was cured by one session of embolization.Although his
gait dramatically improved, he still scores 1 because of his mental retardation and
multiple deficits
Associated dysmaturation of the jugular bulb adds to the complexity of
the situation and should be carefully assessed (see Sect. 3.12).
Developmental delay is part of the natural history of untreated VGAM.
Careful evaluation of neurocognitive performance shows that most children with macrocrania present some degree of mental retardation. In
view of the poor prognosis of the disease, specialists and parents tend to
accept as normal a child with mild retardation (up to 20% of normal for
the chronological age).This level of delay allows the child to attend a normal school albeit with some support. To measure the neurocognitive
3Vein of Galen Aneurysmal Malformation158
Fig. 3.41A–C. Prenatal diagnosis of VGAM.A Male neonate weighing 3,630 g at birth
with a head circumference of 35 cm. Presented cardiac insufficiency responding to
medical management. B Ve ntricular shunting was performed at 3months of age. At
the age of 6 months,MRI demonstrated a spectacular change in the size of the venous
pouch as well as the torcular herophili.The child was referred for embolization at the
age of 10 months. His lesion was completely excluded in two sessions 1 week apart.
C Four years later,exclusion was confirmed, and complete shrinkage of the mass was
obtained. Slight subependymal atrophy persists
159Macrocrania and Hydrocephalus
Fig. 3.42A–C. Legend see p. 160
3Vein of Galen Aneurysmal Malformation160
Fig. 3.42A–E. Following
ventricular shunting (A, B),a
VGAM infant rapidly developed
intracranial hypertension problems connected with (C–E) a
slit ventricle phenomenon.
At that time, no cortical veins
were seen. CAll drainage of
the brain occurred via the veins
of the base, posterior fossa,
or spinal cord. Emergency
embolization was performed at
the age of 6 and 7 months,
rapidly improving the clinical
situation.Additional embolization at 2 and 3 years led to
almost complete occlusion of
the lesion. Seven years later,
the child still has some motor
sequelae from this acute intracranial hyperpressure
episode; however,cognitive
performance is satisfactory.
Her score is 1
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