ABUD, Daniel G

ABUD, Thiago G

MACHADO, Hélio R

NAKIRI, Guilherme S

OLIVEIRA, Ricardo S

SANTOS, Antonio Carlos

Guilherme S Nakiri

Thiago G Abud

Ricardo S Oliveira

Antonio Carlos Santos

Hélio R Machado

Daniel G Abud

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Endovascular treatment of intracranial pial arteriovenous fistula Tratamento endovascular de fístula arteriovenosa pial

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Endovascular treatment of intracranial pial arteriovenous fistula

Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)

 463
Arq Neuropsiquiatr 2010;68(3):463-465
Letter
Endovascular treatment of intracranial 
pial arteriovenous fistula
Guilherme S. Nakiri1, Thiago G. Abud1, Ricardo S. Oliveira2, 
Antonio Carlos Santos1, Hélio R. Machado2, Daniel G. Abud1
Correspondence
Daniel Giansante Abud
Division of Radiology
Medical School of Ribeirão Preto
University of São Paulo
Avenida dos Bandeirantes, 3900
14048-090 Ribeirão Preto SP - Brasil
E-mail: dgabud@gmail.com
Received 15 June 2009
Received in final form 25 July 2009
Accepted 10 August 2009
TRATAMENTO ENDOVASCULAR DE FÍSTULA ARTERIOVENOSA PIAL
Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto SP, Brazil: 1Department of Internal Medicine, Division 
of Radiology; 2Department of Surgery, Division of Pediatric Neurosurgery. 
Intracranial pial arteriovenous fistulas 
(AVFs) are an extremely rare cerebrovas-
cular disease, accounting for 1.6% of all in-
tracranial vascular malformations1. It has 
been recognized as a pathological entity 
distinct from the arteriovenous malfor-
mations (AVMs)2, due to the direct con-
nection between the feeder artery and the 
draining vein, without an intervening true 
nidus. Pial AVFs differ from dural AVFs in 
that their arterial supply derive from pial 
and cortical arteries and they are not in-
volved by the leaflets of the dura-mater1. 
They are in their majority considered to be 
congenital, but they may also occur spo-
radically or in association with congenital 
hereditary vasculopathies3. The pial AVFs 
have a significant morbid-mortality sec-
ondary to its rupture when not treated4. 
We report a case of intracranial pial fis-
tula in a 2 years-old patient presenting sei-
zures since the neonatal period, emphasiz-
ing the angiographic findings and the re-
sults of the endovascular treatment. 
Case
A two years-old female child present-
ed seizures since the neonatal period, con-
trolled with antiepileptic drugs. There was 
no history of head trauma. General and 
neurological examinations were normal. 
Magnetic resonance imaging demonstrat-
ed an enlarged subarachnoid space con-
taining tortuous and engorged pial ves-
sels in the left temporo-parietal region, 
revealing a probable venous shunt with 
distal branch of the middle cerebral ar-
tery (MCA). Angiography demonstrat-
ed a high-flow pial AVF fed by enlarged 
post-central branch of the left MCA, with 
2 fistulous points, each one draining to a 
cortical dilated vein, which converted to a 
single vein before draining to the left sig-
moid sinus (Figs 1A, 1B, 1C and 1D). A 
focal narrowing could be seen right in the 
junction between the draining vein and the 
sigmoid sinus (Fig 1C). 
The endovascular treatment was car-
ried under general anesthesia, with endo-
vascular access by right percutaneous fem-
oral puncture. A 6 F catheter guide was 
placed in the left internal carotid artery, 
and an angiogram was performed to study 
the pial AVF architecture. Selective cathe-
terization of post-central branch of the left 
middle cerebral artery was performed with 
a microcatheter Excelsior 10-18 (Boston 
Scientific, Natick, Massachusetts), which 
was navigated until the venous side of the 
fistula. Embolization was carried out with 
detachable coils (GDC- Boston Scientific) 
placed from the venous side of the fistula 
to the arterial side for each fistulous point 
(Figs 2A and 2B). Post procedure angiog-
raphy showed complete closure of the pial 
AVF (Figs 2C and 2D). The patient was 
discharged home, on postoperative day 3, 
completely asymptomatic. On the 6 month 
follow-up there was no sign of recurrence 
in the angiography, and no new seizure ep-
isode since her treatment. 
DisCussion
Since 1970 less than 100 cases of in-
tracranial pial AVF have been reported. 
They are usually diagnosed during infancy 
or early childhood and are considered to 
be congenital in the vast majority of cas-
es. Acquired pial AVF are very rare, and 
can result of traumatic injury or iatrogen-
Arq Neuropsiquiatr 2010;68(3)
464
Intracranial pial arteriovenous fistula: endovascular treatment
Nakiri et al.
ic causes. Others less frequent causes have been reported, 
as the first case report of a pial AVF secondary to cortical 
vein thrombosis, described by Constantine et al.5. Little 
is known about the pial AVFs pathophysiological mech-
anisms. It is believed that an error in the embryological 
development would be responsible as its etiology. Las-
jaunias6 proposed that structural congenital alterations 
would be primarily responsible for a vascular remodel-
ing process, affecting the endothelial cells at the venous 
side of capillaries. These alterations would stay in a qui-
escent dysfunctional state, and its structural manifesta-
tion would depend on triggers such as mechanical, hor-
monal, hemodynamic, pharmacologic, thermal, radiolog-
ical, infective and metabolical factors. 
Several case reports have described presence of an 
aneurysm in the feeder artery of pial AVFs, which could 
potentially explain the high rate flow in the artery as a 
hemodynamic trigger in their pathogenesis mechanism7. 
Pial AVFs in Moya-Moya disease and following cerebral 
vein thrombosis suggest ischemia or hypoxia is an impor-
tant etiological factor5-7, which is reinforced by the fact 
that hypoxia is a powerful trigger for the up-regulation of 
angiogenic factors expression8. 
Pial AVFs can cause seizures, hemorrhage, headache, 
neurological deficit and symptoms of increased intrac-
ranial pressure3,6,9. Its diagnosis is usually made between 
2 and 5 years-old. In neonates and infants it can induce 
cardiac failure, macrocephaly and formation of a palpa-
ble mass due to giant varices3,9.
The natural history of the pial AVFs remains unclear 
because of its rarity. Spontaneous closure of the pial AVF 
cannot be expected, since only one case has been report-
ed in the literature. The high flow and perfusion pressure 
in pial AVFs due to the direct arteriovenous shunt can 
lead to formation of giant varices10. 
Treatment can be performed through shunt discon-
nection by microsurgery or endovascular intervention, 
dispensing resection of the vessels involved in the fistula, 
like demonstrated by Hoh et al.1. 
At one institution the choice between these two ther-
apies should take in account the personal experience of 
professionals involved. 
The embolic agents used preferentially for endovascu-
lar therapy are detachable coils and acrylic glue. In single 
hole fistula, with single artery-single vein arteriovenous 
(AV) shunt, the placement of coils is feasible with the ad-
vantage of a better controlled positioning of the embol-
ic material, since it can be withdrawn several times be-
fore being detached. In complex fistulas, in which there 
are many AV communications or multiple arterial feed-
ers with single vein outlet, use of liquid glue is preferred 
due to its capability of filling all the AV connections com-
pletely and especially the micro AV connections. 
In our case 2 single-hole fistulas were present, each 
Fig 1. Lateral internal carotid artery (ICA) injection in early [A] and 
late [B] phases showing a high-flow AVF draining to a dilated vein, 
and then to the sigmoid sinus. [A] High-flow pial AVF fed by en-
larged post-central branch of the left MCA (arrow). [B] Focal nar-
rowing (thick arrow) in the junction between the draining vein 
and the sigmoid sinus (thin arrows). [C] Left anterior oblique view 
demonstrating the two fistulous points (arrows), each one drain-
ing to a cortical dilated vein, which converted to a single vein be-
fore draining to the left sigmoid sinus. [D] Posteroanterior view, in 
late phase after ICA injection.
Fig 2. [A] “Road map” angiogram during the deployment of the 
detachable coils (arrow). [B] Lateral plain film after detachment of 
the coils in the 2 fistulous points (arrows). [C/D] Postembolization 
lateral ICA angiogram, in early phase [C] and late phase [D], show-
ing complete closure of the fistula.
Arq Neuropsiquiatr 2010;68(3)
 465
Intracranial pial arteriovenous fistula: endovascular treatment
Nakiri et al.
one draining separately to a single vein before converg-
ing to a single venous channel. Two selective microcath-
erization were performed with complete closure of both 
fistulous points. No ischemic or thromboembolic event 
occurred during the procedure. 
In conclusion, because Pial AVF has a poor natural 
history and significant morbid-mortality secondary to its 
rupture and bleeding, a prompt diagnosis followed by ap-
propriate treatment is very important. With the advanc-
es of microcatheters and embolic agents, the endovascu-
lar approach has been established as an efficient and safe 
procedure for the treatment of pial AVFs.
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