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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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status during follow-up, pediatric neurologists recommend the Denver
test (Frankenburg et al.1992) and the Brunet-Leisine test,which are easy
and reproducible (see Chap. 2, this volume) for the purpose of therapeutic decision making.
The developmental phenomenon is not one-dimensional.Development
of different skills can be quite independent of other skills, and development of a single skill is usually influenced by multiple interactive factors.
Development rates are determined by a variety of factors such as heredity,
biological intactness, emotional health,as well as the physical and psychological environment. Deviation in development profiles is usually the result of multiple etiological factors. For instance, a child suffering from a
hearing loss will have a different development profile than a child suffering from cerebral palsy or social depravation.One should interpret the developmental status of a child at one point in time with caution. It is more
important to look at the rate of development over time and interpret the
result together with what is known about the child’s background (see
Chap. 2, this volume). Such tests are not meant to compare children, but
are meant as an aid to follow a child’s ongoing development.
The difference between the chronological age and the age apparent on
testing is the basis for neurocognitive delay that we refer to in our scoring
system. A 20% developmental delay is significant, but below 20% most
children will catch up with continuation and eventually completion of
endovascular treatment of the VGAM. Although there is no direct relationship between the degree of macrocrania and the severity of developmental delay (the head enlargement actually protects the brain),there is
an obvious link between hydrodynamic disorders and the delay. Any
event that creates a loss in compliance has an impact on brain maturation,e.g., intracranial hypertension, spontaneous decrease in the head
circumference,or ventricular shunting.
The specific evaluation score in VGAM neonates cannot be used for
clinical follow-up in infants. We have chosen a more global clinical admission and outcome assessment. Although this type of quantification
may lack certain details, it has been good enough to follow the progression in a given child.The use of these scores has helped us rationalize and
compare our decisions and verify their stability over the past 20 years.
Cardiac manifestations are differentiated into absent (5), asymptomatic cardiac enlargement (4), overload treated (3), failure stabilized
(2), unstable failure (1). Macrocrania represents a non-neurological
symptom, which is usually not treated and is assigned a score of 4.
Children with a ventricular shunt who are neurologically asymptomatic or who have had an isolated seizure that is not treated have a
score of 3. Children with seizures that are medically treated, or children with a delay of less than 20% have a score of 2.A unilateral hemianopsia, regardless of its cause, warrants a score of 2. Hemiparesis or
monoparesis are serious neurological symptoms in infants and are
assigned a score of 1 whatever the neurocognitive function (motor
neurological deficit following ventricular shunting are included
here).
161Macrocrania and Hydrocephalus
The next step is often marked by the effect of macrocrania on the skull
base venous maturation. It should be considered in two parts, depending
whether the sinuses have remained patent.Obviously no scoring is accurate in all situations and a new but persistent mild deficit in a 13-year-old
child will not have the same meaning or prognosis as the same symptom
in an 8-month-old infant without macrocrania.
3.11 Late Natural History of Vein
of Galen Aneurysmal Malformation with Patent Sinuses
This stage and its subsequent evolution can be described as chronic. All
the possible acute damage has occurred by now.All manifestations clinically detected represent subacute and chronic manifestations of venous
ischemia or brain loss due to the previous hydrodynamic disorders
(Fig. 3.40). Seizures and mental retardation are the main symptoms seen
if the correction of the AV shunt was not done in time,and they often occur in children who were referred late in the development of their disease
or after ventricular shunting. Therefore, convulsions are not a necessary
phase through which all VGAM patients pass, but rather indicate poor
timing of treatment.Some patients with completely excluded VGAM and
late cavernous sinus capture have developed pseudo-phlebitic appearance of the cortical veins. In some these cases, a seizure may reveal a
focal cortical vein thrombosis requiring coagulation profile analyses and
anticoagulation treatment (Scheme 2.1D).
3Vein of Galen Aneurysmal Malformation162
Scheme 3.1D. Late neurological disorders
Some unusual endocrine manifestations have been reported, such as
precocious puberty and failure to thrive.Pineal involvement and recruitment of the hypothalamohypophyseal portal system may constitute elegant explanations for the few cases quoted.However,they do not provide
an explanation for all the apparently similar situations in which this
endocrine dysfunction does not occur.
Cerebral morphological sequelae express themselves in calcifications
(Fig. 3.43), subependymal atrophy (pseudo-ventriculomegaly; Fig. 3.44),
163Natural History of Vein of Galen Aneurysmal Malformation with Patent Sinuses
Fig. 3.43A–D. Girl presenting with headaches at the age of 8 years; VGAM was diagnosed. A,B The lesion has a peculiar appearance with a reflux into choroidal veins (C,
D). Note the unusual calcification in the putamina-caudate nuclei on both sides in association with more conventional types of subcortical calcifications
and eventually the stigmata of previous acute accidents with cortical and
subcortical atrophy (Fig. 3.45).
It should be noted that in VGAM with patent sinuses, as opposed to
cerebral AVMs, local or regional melting-brain phenomena are not encountered,since pial and therefore subpial reflux do not occur.The insult
to the brain is therefore a slow and permanent one,as testified by the calcifications. There are different types: mural in the lesion itself where the
calcifications are secondary to its partial or complete thrombosis; at the
subcortical in the white matter,they reflect deep hydrovenous watershed
failure. The latter occurs when the compliance of the medullary veins loses its ventriculocortical gradient and its activity is shifted from the subpial level to the medullary level (when pressure in the subarachnoid veins
increases progressively following closure of the sutures).These calcifications are usually bilateral and symmetrical, located preferentially in the
frontal region.The occipital lobe region is often affected earlier and may
undergo subependymal atrophy with subsequent focal occipital horn enlargement and a thin splenium of the corpus callosum (Fig. 3.45). They
may be asymmetrically located, mostly in unilaterally shunted children
and often on the side opposite the shunt. These calcifications are not
caused by a so-called cerebral arterial steal (Yu et al.1987).Any transient
episode of hydrocephalus may give rise to such calcifications, since it
expresses the loss of compliance in the fragile hydrovenous system functioning in infants. A third type of calcification is located in the striatum
and in the caudate and putamen bilaterally and symmetrically.These calcifications express subacute ischemia in the region of the prominent
transcerebral collateral circulation system for the telencephalic veins.
Striate vein congestion occurs after the cortical veins can no longer drain
the cerebral white substance or when the persisting thalamic pathways
(mainly diencephalic and rarely telencephalic) are overloaded with the
drainage of the parieto-occipital regions. The calcifications indicate both
3Vein of Galen Aneurysmal Malformation164
Fig. 3.44. A 4-year-old child
was referred because of a neurological deficit and seizure in
a neglected VGAM.The child
presented with transient and
recurrent motor hemiplegia on
the left side. MRI demonstrated
VGAM with significant bilateral
calcifications in the subcortical
region, but also in the putamina-caudate region,indicating
transcerebral venous collateral
circulation in the brain
the mechanism and the specific vulnerability of this area at the infant
stage. The clinical manifestations do not parallel the intensity of these
calcifications. Some of them demonstrated during infancy after a brief
episode of increased intracranial pressure may be absent on follow-up
CT.Therefore,although indicative of a previous ischemic insult,the calcifications do not have a predictive value for neurological outcome in a
treated VGAM. They rarely produce abnormal movement disorders that
are most often seen with more posteriorly located damage.
Subependymal atrophy is primarily seen in the occipital regions as a
spontaneous progression ofVGAM (see Fig. 3.46). It may be dramatic and
165Natural History of Vein of Galen Aneurysmal Malformation with Patent Sinuses
Fig. 3.45A–B. Infant girl diagnosed as having VGAM because
of macrocrania and prominent
facial veins. The child received
stereotactic radiosurgery at
10 months. Because of the failure to obtain a satisfactory
result, the patient was referred
to us at the age of 3.5 years with
mild mental retardation.
A CT shows diffuse bilateral
and symmetric white matter
calcifications and B a mural
type of VGAM. C see p. 166
3Vein of Galen Aneurysmal Malformation166
Fig. 3.45. (continued)
C The child was later embolized
and her VGAM completely
occluded in one session
Fig. 3.46A,B. MR studies 3 weeks apart showing the rapid changes occurring at the
occipital horns of the lateral ventricles
seems to be at least partially related to corpus callosum postnatal developmental delay. This atrophy remains reversible for a long time,with parallel growth of the splenium and a decrease in size of the occipital horn.
Children that have undergone ventricular shunting do not show equal
capacities for this correction and keep large ventricles at low pressure
and a thin corpus callosum. Calcifications do not reflect an progressive
process, but are rather scarring of past long-lasting insults. It seems that
the degree of clinical sequelae depends on the severity of the brain insult
over time and the rapidity with which appropriate correction of the disorders took place. This highlights the inability of imaging modalities to
appreciate the true substrate of the neurological handicap. Focal evidence of iatrogenic hemorrhagic or acute hydrocephalus is infrequent,
and their incidence should further diminish with the increased use of
early endovascular management of macrocrania. Cerebral angiography
may provide crucial information, as it demonstrates that, in the absence
of pial reflux and in the absence of late venous thrombosis, hemorrhage
does not occur.Exceptional association with subependymal cavernomas
has been seen without introducing a new nosological entity.The rarity of
such association does not justify a specific screening.
It is important to realize that the clinical outcome of children with
patent sinus outlets is relatively good compared to those with secondary
occluded sinuses. This is probably the most clinically relevant observation to be derived from angioarchitecture analysis in infancy.
3.12 Dural Sinus Occlusion and Supratentorial Pial
Congestion and Reflux
Dural sinus occlusion and supratentorial pial congestion and reflux correspond to a dysmaturation of the jugular bulbs.The persistent medial occipital and marginal sinuses with VGAM flow seem to delay transverse sinus
development. Most of the efferent torcular flow seems directed medially
and does not trigger the sigmoid sinuses that remain distally thin.When finally the medial occipital and marginal sinuses disappear, the sigmoid sinuses will have fully occluded distally. The extracranial jugular veins are
still patent and receive the inferior petrosal sinus (Fig. 3.47) (Scheme 3.1E).
This progression of the VGAM is a very common one,although seldom
recognized as the reason for a significantly different clinical outcome.
The cause of the thrombosis is unknown, even if we acknowledge the influence of abnormal skull base growth maturation caused by macrocrania as opposed to a venous high-flow angiopathy. Thrombosis is one of
hallmarks of AVM in children as compared to those in adults. Thrombosis is usually progressive and may develop slowly and without symptoms
over a long period of time.
In one neonate, a mild CCF was noted at the age of 10 days; which was
well tolerated and therefore left untreated. MRI done at 2 months of
age when the child presented with a slight macrocrania demonstrated
a sinus thrombosis and a cerebellar area of hemorrhagic infarction (see
Fig. 3.41).Although the infant had been asymptomatic,the fear of an impending acute event prompted angiography and embolization at that
167Dural Sinus Occlusion and Supratentorial Pial Congestion and Reflux
3Vein of Galen Aneurysmal Malformation168
Fig. 3.47. A A 15-month-old boy presented with a mural VGAM with cardiac insufficiency and macrocrania. Tonsillar prolapse and ventricle dilatation resulted from
jugular bulb occlusion. There was no mental retardation in relation with good cavernous drainage and inferior petrosal sinus drainage. Note the rarefaction of the temporal veins in relation to the sigmoid sinus thrombosis.VGAM diagnosed with macrocrania; the child was surgically shunted. He was referred at 12 months with severe
mental retardation.Jugular foramen narrowing is present; however, no pial venous reflux is seen.B Collateral circulation uses posterior fossa venous outlets.Note in particular the perimesencephalic and peripontine vein outlining brain stem structures
time.The sinuses proved to have reopened,and embolization was carried
out and repeated over time. At 4years, the child was neurologically normal, had a score of 4 and has never had a further episode related to
venous impairment.
In some cases, time-of-flight magnetic resonance venography (MRV)
may not show the jugular bulb stenosis or occlusion, mainly because of flow
artifact or insufficient attention being paid to such features, but MRI with
contrast enhancement should be able to reliably assess the status of the dural sinuses. Angiography demonstrates the secondary nature of the process
and its effect on cerebral circulation. The development of a jugular bulb
stenosis protects the heart but exposes the brain.Not only does it interfere
with water resorption, but it also creates congestion within the cerebral
veins.All symptoms will depend on the timing between the upstream effects
of the stenosis and the capture of the sylvian veins by the cavernous sinus.
The overall prognosis of an untreated VGAM is therefore largely
dependent on the patency of the jugular bulbs.The more restricted the venous outlets, the less compliant the system. In the presence of moderate
jugular bulb stenosis and capture of the cerebral veins by the cavernous sinus outlets,macrocrania and developmental delay may stabilize,as long as
the stenosis does not progress further.The veins of the foramen ovale will
be recruited, and in other situations the ophthalmic veins will reroute the
brain drainage toward the facial veins (Fig. 3.48).This development facilitates the facial veins becoming collaterals in infants; they are not present at
neonatal age, as the redistribution and capture of veins has not yet occurred. Under these circumstances, the combination of a VGAM and
169Dural Sinus Occlusion and Supratentorial Pial Congestion and Reflux
Scheme 3.1E. Pial reflux
prominent facial veins is a good indicator relief of cerebral venous hyperpressure in the absence of sigmoid sinus occlusion.
If the jugular bulb stenosis is more severe or if a unilateral sigmoid sinus thrombosis has occurred,the VGAM and the brain may drain into the
same cavernous sinus outlets (see Fig. 3.49). The VGAM will drain via the
recently captured sylvian vein, and the brain via the superior petrosal
sinus. If the transcranial openings are sufficiently patent, then the indirect effect of congestion is apparent on angiography as a phlebitic type of
appearance of the cortical veins (Fig. 3.50). Despite this feature, clinical
tolerance is still good. Epistaxis related to nasal vein congestion may
occur, indicating increased flow through the ophthalmic vein (rather than
an alternative hydrovenous pathway along the olfactory tract). Depending on the patency of the inferior petrosal sinus beyond the jugular occlusion,the cerebral pial congestion may exist without reflux.The long-term
result is a chronic ischemic phenomenon with delayed calcifications
and the peculiar appearance of the cortical veins. Conversely,if the superior-to-inferior petrosal sinus collateral bypass is not sufficiently patent,
a longer collateral circuit for the VGAM drainage is necessary. Pial
3Vein of Galen Aneurysmal Malformation170
Fig. 3.48. A Female neonate diagnosed as having VGAM due to severe cardiac overload. Embolization had to be performed at 2months of age.At 8months of age, progressive macrocrania and facial circulation appeared, and cardiac overload had resumed. Note the facial circulation at 12 months.B Six years later,the lesion was completely occluded.The child was normal at 13 years of follow-up
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