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7Dural Arteriovenous Shunts432
Fig. 7.23A–D. This infant is a neurologically healthy 37-week-old,2,900-g, megaloencephalic, 37-cm head circumference female with no dysmorphic features. There is a
generous dilatation at the posterior part of the sagittal sinus at the point where it
meets with the transverse and straight sinuses. The dilatation is to the right of the
midline without causing any hydrocephalus. Doppler revealed venous low flow into
the defect. The diagnosis of DSM was made (A, B). Six months later, the normally
developing lesion has thrombosed completely; despite large pericerebral spaces, the
venous remodeling is normal (C, D)
433Fetal and Postnatal Changes of Sinuses
Fig. 7.24A–E. A child a few days old with MR and
MRA evidence of DSM (A–C). Angiographic evaluation
shortly after failed to demonstrate residual AVS;
venous remodeling is the only stigmata of the
previously demonstrated DSM (D, E)
7.3.2 DSM of the Jugular Bulb
There are some minor sigmoid sinus–jugular bulb junction malformations that are seen at a slightly later age than the major ones illustrated in
the previous section.We consider them as belonging to the malformation
group in view of the diaphragm-like obstacle present at the level of the
jugular foramen.We postulate that the abnormal onset occurs late in the
maturation of the high jugular bulb and after the marginal sinus thromboses. The development of the AVF from the mastoid branch of the occipital artery and the subsequent high-flow angiopathic changes appear to
be secondary phenomena (Okudera et al.1996). They are often asymptomatic and most of the time discovered incidentally because a pulsatile
bruit is heard by the parents, the child’s teacher, or the pediatrician. The
child does not complain of the bruit as it is part of his a normal acoustic
environment. Silence secondary to the successful occlusion of the lesion
may create a disturbance in the child’s attitude.Appropriate explanation
and preparation of the child and parents is recommended.
Conservative treatment is probably acceptable if alternative pathways
are present early enough to offer the brain the hydrovenous equilibrium
it needs for proper morphological and neurocognitive maturation. Yet
the presence of a craniopetal reflux into the lateral sinus and toward the
opposite side suggests a probable future risk for venous congestion
(Fig. 7.25). Evidence of a pial venous reflux, even in asymptomatic patients, represents an indication for endovascular treatment (Fig. 7.26).
These well-tolerated malformations have an excellent outcome following
endovascular management.
7Dural Arteriovenous Shunts434
Fig. 7.25. A 15-month-old boy presented with progressive macrocrania for several
months. The parents found a pulsatile right retroauricular mass. Physical examination showed a normally growing child with mild macrocrania. The anterior fontanelle
was soft. Clinically,there was no tachycardia and there were no signs of heart failure.
Developmentally, he had normal milestones. Angiography shows single AVF of the
sigmoid sinus with jugular diaphragm (A, B). Selective catheterization and glue embolization of the occipital supply allowed complete exclusion of the lesion (C,D). Note
the normal drainage of the brain (E) and the disappearance of the meningeal supply,
although not embolized (F).(Kwong 2001)
▲
435DSM of the Jugular Bulb
Fig. 7.25. Legend see p.434
7.4 Infantile Dural Arteriovenous Shunts (AVS)
Infantile DAVSs are the most frequent type of pediatric DAVs in the literature. They are dural high-flow AVSs seen at various pediatric ages, often
multifocal, with sinuses that are patent for a long time and the occurrence
of induced pial AV shunts (Table 7.8).The difficulty in this disease entity is
that the effects of high-flow angiopathy are usually not recognized as such.
Some cases, although different in appearance,are in fact two stages of the
same disease; conversely, two lesions that look the same and therefore are
classified similarly may in fact be separate and different entities. Depending on the age at onset of the lesion, the symptoms will be different.
Neonatal or infant onset is marked by CCF manifestations, which are
rare and infrequently require emergency management. In most instances,the CCF is mild and discovered retrospectively because of an enlarged cardiac silhouette.As all the sinus outlets are still patent at this age,
there are no neurological manifestations.Management of the CCF can be
similar to that of VGAM,and neonatal scores can be applied when necessary.The dural sinus high flow is often associated with low venous sinus
pressure because of the high velocity, and secondary hydrovenous complications are less frequent than one would expect. The drainage will be
craniofugal for a long time, usually unilateral without contralateral dural
sinus drainage reflux,despite the associated high flow.The hydrodynam-
7Dural Arteriovenous Shunts436
Fig. 7.26A,B. Male infant presenting at 7 months of age with macrocrania due to subdural hygroma. During shunt placement for drainage, large malformed vessels were
seen. At the age of 2 years, facial collateral circulation was seen around the eyes and
face bilaterally; a loud bruit was heard over the right suboccipital area. A, B Angiographic study showed a dural arteriovenous shunt with malformed sinus and pial
reflux. At the age of 2 and 3 years,the child was embolized completely. At the age of 4,
he was clinically normal and started preschool
ic disorders do not interfere with brain maturation to the same degree as
they do in VGAMs at the same age, and mental retardation remains moderate. This explains why most of these lesions are diagnosed in children
rather than during the first 2 years of life. Some of them seem to be secondary to a head trauma or facial or orbital surgery. Following a free interval of several years,the DAVS becomes symptomatic,since it is located
some distance from the trauma or the surgical field.
Two types of progression can be seen: persistent high flow and pro-
gressive outlet restrictions.
The persistence of the high flow, but with low pressure in the large
sinuses, creates several remarkable phenomena (Scheme 7.7). The first is
the development of induced corticopial AVSs (Figs. 7.3, 7.27) with opening of the cortical draining veins into the abnormal sinus.The dural sinus
sump effect creates a remote venous steal upstream; it is not symptomatic
as such, but probably produces some degree of white matter venous
ischemia over time. The natural history of these pial AVSs is not known
and some will regress following occlusion of the primary dural AV shunt.
The persistence of the latter is,however, sufficient to provoke the enlargement of these pial lesions over time and even some flow-related aneurysmal ectasias proximal to the pial AVS on their arterial feeders as well as
the meningeal arteries (Fig. 7.28). Partial, targeted treatment of these
pial AV communications may give the impression of improved security,
without formal evidence of a preventive clinical effect. The risk of these
induced micro-AVSs is unknown, and the rationale to treat them is
extrapolated from our experience with pial cerebral AVMs (CAVMs).
The second characteristic of this type of progression is the development of multifocality,the opening of different zones of AV shunting along
the dural sinuses.They may be at the skull base unilaterally,but may also
be located supra- or infratentorially (Fig. 7.29). This type of progression
should be differentiated from converging bilateral supra- and infratentorial dural supply to a single arteriovenous zone.With such features,these
437Infantile Dural Arteriovenous Shunts (AVS)
Ta ble 7.8. Comparative anatomical and clinical features in neonatal and infantile dural vascular lesions
Neonates and infants Infants and children
Etiopathogenesis Sinus malformation Secondary development triggered
Angioarchitecture Unifocal giant pouches; spontaneous Multifocal; large sinuses without lakes;
dural venous thrombosis; small, possible jugular bulb occlusion; induced pial
slow-flow shunts AV shunts; high flow,high velocity
Progression Acute Subacute or regressive manifestations
Clinical progression
Initial Systemic, convulsive Macrocrania
Secondary Venous reflux,infarct/hemorrhage Mental retardation/progressive neurological
deficit, depending on secondary sinus
occlusion
With treatment Unfavorable; depends on the degree
of sinus malformation
Name of lesion Dural sinus malformation with AV shunt Infantile dural AV shunt
AV, a r t e r i o v e n o u s .
lesions express a strong angiogenic activity mostly on the venous side,
with de novo AVS and shear stress-induced dural arterial aneurysms.
Converging supply, while very common in children, is not specific for
this age group, but rather represents the normal dural capillary angioarchitecture and its rapid local angioectatic response to the de novo AVS.
The unfavorable influence of multifocality in this infantile type of DAVS
depends on its overall impact of the total sump phenomena and the relative venous ischemia without reflux that progressively develops. With
time,moderate macrocrania and mental retardation will be noted, while
cranial nerve deficits are often the initial symptom.Alternative pathways
through the cavernous sinus also produce corresponding proptosis,
extraocular motor nerve palsies, and facial vein enlargement. The recruitment of all sinuses precludes their endovascular sacrifice; arterial
embolization is always partial, and the disease’s progression in several
foci is responsible for recurrences.These do not occur through reopening
of proximally or insufficiently occluded portions, but following the development of new shunting zones in the vicinity of the ones embolized a few
months after the last treatment.
The second type of progression is more typical in this age group and is
associated with a relatively higher dural sinus pressure. Subsequent to
macrocrania, unilateral or bilateral jugular bulb stenosis and occlusion
will (a) increase hydrodynamic manifestations,(b) provoke bilateral pial
7Dural Arteriovenous Shunts438
Scheme 7.7. Natural history of infantile dural arteriovenous shunts (DAVS). In the
literature,neonatal onset and the neonatal type are often confused. Neonatal onset is
rare: 20 cases of neonatal onset have been published,and all types of dural AV shunts
(malformation,infantile,adult) can be seen.DAVS accounts for 10% of all intracranial
shunts in children
439Infantile Dural Arteriovenous Shunts (AVS)
Fig. 7.27A–F. Juvenile dural AVS.An 11-year-old girl with progressive hemiplegia on
the left side with diplopia and severe headaches. Proptosis, intracranial bruit, and
cerebellar syndrome were also noted. A Angiography demonstrated a high-flow arteriovenous shunt extending to the sinuses bilaterally,predominantly on the right side.
In addition,there was B extension in the superior petrosal sinus and C a direct fistula
on the sigmoid sinus. C–E Remote pial shunts were seen on the surface of the cerebel-
lum (arrow in D) and supratentorial structures. Several embolizations with partial
control of the shunting zone at the dural level improved the child’s condition. However, symptoms always recurred 3–8 months following each session. F The child eventually died with a posterior fossa syndrome at the age of 16 years.E,F see p. 440
venous congestion,and (c) rapidly lead to pial reflux,in addition to all the
chronic effects of hydrovenous venous hyperpressure (Vilela et al.2001).
At this point, all the classical manifestations described in Chap. 2 of this
volume may be encountered, including tonsillar prolapse (Figs. 7.15, 7.16,
7.27) and eventually syringomyelia (Fig. 2.28; Apsimon 1993).
Neurological symptoms are either related to congestion without reflux
and lead to seizures and transient deficit or mental retardation, depending on the degree of cavernous sinus capture,or to pial reflux with venous
hemorrhage, seizures,and progressive deficits. Treatment of these forms
seems easier, and progression to multifocality is rarely observed,suggesting that high velocity is the dominant trigger for this particular feature of
progression.The sinuses remain large, despite the reduction in their outlets. In this type of DAVS, computed tomography (CT) does not give
7Dural Arteriovenous Shunts440
Fig. 7.27E,F. Legend see p. 439
441Infantile Dural Arteriovenous Shunts (AVS)
Fig. 7.28A–C. Juvenile dural AVS. A young boy presenting in early infancy with
macrocrania and ventriculomegaly that led to ventricular shunting. He was referred
to us at the age 12 with an intracranial hematoma.Angiography demonstrated a complex dural arteriovenous shunting zone involving several sinuses. A–C Later, angio-
graphy showed dysplasic changes and all possible dural branches supplying the
various sinuses converging to the surgical field. Note the aneurysms on the dural arteries. Following partial embolization, some of these dysplastic changes were augmented, despite significant reduction in the flow of the lesion and clinical improvement. Multiple embolization procedures were performed with transient improvement. He died at the age of 17 from irreversible posterior fossa syndrome without
hemorrhage
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