Journal of Clinical Neuroscience 68 (2019) 317–321

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Journal of Clinical Neuroscience
journal homepage: www.elsevier.com/locate/jocn

Tools and techniques

Thrombosis of the straight sinus and microbleedings due to deep seated
arteriovenous fistula – Hemodynamic changes, cognitive impairment
and improvement after microsurgery. A technical report
Nazife Dinc a,⇑, Won Sae-Yeon a, Eibach Michael a, Quick-Weller Johanna a, Keil Fee b, Berkefeld Joachim b,
Konczalla Jürgen a, Marquardt Gerhard a, Seifert Volker a
a
b

Department of Neurosurgery, Goethe University Hospital, Frankfurt, Germany
Department of Neuroradiology, Goethe University Hospital, Frankfurt, Germany

a r t i c l e

i n f o

Article history:
Received 16 November 2018
Accepted 5 July 2019

a b s t r a c t
Dural arteriovenous fistulas (dAVF) are rare vascular malformations accounting for only 10–15% that may
lead to life threatening deficits due to hemodynamic changes in blood supply and pressure conditions.
We present a 64-year old patient who was admitted with disorientation and aphasia.
Following images confirmed an infratentorial dural fistula draining into the straight sinus. Additional
findings were progressive thrombosis of the straight sinus, microbleedings and bithalamic edema due
changes in hemodynamic conditions and venous congestion. Microsurgery was performed. After treatment improvement in clinical condition was observed and the venous congestion was regressive.
Hemodynamic changes due to infratentorial dAVFs may lead to bleedings in deep regions and worsening of clinical condition fastly. Treatment requires carefully planning and visualization of angioarchitecture. Symptoms and hemodynamic changes are reversible after treatment, which are essential for
treatment decisions.
Ó 2019 Elsevier Ltd. All rights reserved.

1. Introduction

3. Results

Dural arteriovenous fistulas (dAVF) are rare vascular lesions
accounting for 10–15% of all intracranial vascular shunts [1–7].
Tentorial dAVF represent a subgroup of dAVF accounting for 4%
and are potentially hazardous acquired lesions [1,7–10]. The etiology is discussed controversial and the association with venous or
sinus thrombosis is described in several studies [6,11–14].
We report a case of a straight sinus fistula with arterial blood
supply from the left superior cerebellar artery, sinus thrombosis,
bithalamic venous congestion and deep microbleedings.

3.1. Imaging findings before treatment

2. Patient and methods
A 64 year old male was presented with disorientation and aphasia. For a short time he showed a mild confusion with memory deficits and speech arrest. An intracerebral hemorrhage was ruled out
by a computed tomography. The sonography of the cervical vessels
excluded any high grade stenosis and magnet resonance imaging
(MRI) and cerebral angiography was planned.
⇑ Corresponding author at: Dept. of Neurosurgery, Goethe-University Frankfurt,
Schleusenweg 2-16, 60528 Frankfurt, Germany.
E-mail address: nazife.dinc@kgu.de (N. Dinc).
https://doi.org/10.1016/j.jocn.2019.07.012
0967-5868/Ó 2019 Elsevier Ltd. All rights reserved.

The MRI at presentation revealed a fistulous infratentorial arteriovenous malformation from the left superior cerebellar artery
with stenosis of the straight sinus. Bithalamic edema were defined
as a sign of venous congestion.
The first angiography confirmed the straight sinus fistula
(Fig. 1). Significantly delayed antegrade drainage with stenosis just
proximal to the confluens sinuum and very low contrasting and
reflux into small veins of the thalamus and venous congestion were
detected. The dAVF was classified as a Cognard IIb fistula [15,16].
The MRI two months later showed persistent early contrasting
of the straight sinus as a sign for arterial flow. The thalamic edema
were regressive but bithalamic hyperintense regions due venous
congestion on FLAIR and DWI-sequences were still existing.
Multiple microbleedings bithalamic and at the posterior part of
the splenium were detected on T2w*.
Due to a renewed confusion and worsening of patients clinical
condition 9 days later MRI was performed again. An increasing of
the bithalamic right-sided edema with progression of venous
congestion, now with thrombosis of the posterior part of the
straight sinus was detected (Fig. 2).

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N. Dinc et al. / Journal of Clinical Neuroscience 68 (2019) 317–321

Fig. 1. Angiography series prior treatment A, B: Angiography (C: CT angiography; D-F: 3-dimensional angiography;) reveales infratentorial dAVF with blood supply from the
left superior cerebellar artery, draining to the straight sinus.

3.2. Thrombophilia screening

3.3. Treatment

For excluding thrombophilia as a predictive factor for the development of venous clots we performed a coagulation-screening.
There were no pathologic findings considering factor V Leiden, factor VIII, protein C and S deficiency and antithrombin deficiency.

The case was discussed in the interdisciplinary vascular board.
Due worsening in clinical state and rapid hemodynamic changes
within 9 days the decision was to perform microsurgery immediately at the following day.

Fig. 2. MRI series prior treatment Preoperative MRI on sagittal T2 showing early contrasting of the straight sinus (A–B) and microbleedings bithalamic and at the corpus
callosum in T2*w (C). 9 days later early contrasting of the anterior third part of the straight sinus. The posterior part of the straight sinus is thrombosed (D–E). Microbleedings
and bithalamic edema in T2*w (F).

N. Dinc et al. / Journal of Clinical Neuroscience 68 (2019) 317–321

3.4. Surgical procedure
After performing an echocardiography and excluding a patent
foramen ovale the patient was placed in the sitting position with
gentle neck flexion to maximize gravity-assisted retraction of the
cerebellum. Intraoperative electrophysiology with sensory and
motor evoked potentials were recorded.
We used a midline linear skin incision. A suboccipital craniotomy was performed for an infratentorial supracerebellar access.
The exposure of the transverse sinus was necessary as the inferior
edge of the sinus can be gently mobilized superior and allow
upward retraction of the transverse sinus. After opening and
retracting the dura flaps we divided the arachnoid bands carefully.
Fenestration of the cisterna magna released cerebrospinal fluid and
allowed brain relaxation. After detaching all arachnoid connections
and visualizing the cerebellar surface vascular landmarks were
identified. To preserve and protect bridging veins and to evade
diminished visibility of the surgical access we performed a right
paramedian trajectory. The confluence of the internal cerebral
veins and basal vein of Rosenthal were carefully identified and preserved. After sufficient visualization of the cerebellar surface, small
arteries were visible along the surface. They run into a larger artery
and drained directly into the straight sinus. Then indocyanine
green (ICG) angiography was performed and showed the fistula
point clearly. The thrombosed part of the straight sinus was visible
proximal to the fistula. We coagulated the arterial fistula and
clipped it with a straight clip. Renewed ICG angiography confirmed
occlusion of the fistula and demonstrated a retrograde perfusion of
the straight sinus. After watertight dural closure the bone was
replaced and wound closure was performed. The recorded evoked
potentials remained normal during the entire procedure. Fig. 3
shows the surgical clip occlusion of the infratentorial dAVF.
3.5. Imaging findings at early follow up and outcome
Postoperatively the first MRI and angiography confirmed the
occlusion of the fistula. Bithalamic edema were still visible.
In early MRI follow up 3 months later the bithalamic edematous
changes were regressive compared to the preliminary studies. Only
residuals in the thalamus on the right side were visible on T2Flair,
without infarctions or hemorrhage (Fig. 4). The patient was in a
favorable clinical condition and showed no neurological deficits
and no confusion.
4. Discussion
The pathophysiology of dAVF remains still unclear and is discussed controversial. A multifactorial development is described
like head trauma, craniotomy, meningiomas, infections or thrombophilic pathologies [17–19]. A relation to sinus thrombosis with
opening of small physiological arteriovenous pathways from the
sinus or abnormal connections during the recanalization process
is proposed [20,21]. The formation of a thrombosis at some stages
in fistula development, possibly due to stenosis thickening of sinus
wall which leads to turbulences with subsequent thrombus formation is described as well [20,22]. Furthermore thrombosis of the
sinus could be a trigger for de novo fistulas [11]. The occlusion of
a dural sinus or a cerebral vein may cause alterations in hemodynamics, which may contribute to arteriovenous shunts [17].
In adults dAVF typically presents with venous or sinus thrombosis, in children the etiology is usually congenital [23]. The association with thrombophilic polymorphism and dural fistula is
described in some studies but the literature therefore is rare and
limited to case reports and a small number of studies [5,24,25].
In particular, dAVF may be a considerable cause of vascular cogni-

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tive impairment. Venous congestion due to hemodynamic changes
with progressive thrombosis and venous hypertension are
described as a serious finding and reason for cognitive disorders
in high flow dAVF [26]. However, cognitive disorders are reported
in previous studies with discrepant frequencies. The rate of mental
deterioration in patients with dAVF in the transverse-sigmoid
sinus ranges between 12% and 22% [26–28]. In addition to neurodegenerative disorders, prion disease, autoimmune encephalopathies or some infections and neoplasms, dAVF may be a reason
for rapid progressive dementia [29]. Seizures, focal cortical deficits,
cranial nerve palsies, trigeminal neuralgia, thalamic or cortical
dementia, parkinsonism, cerebellar dysfunction, myelopathy,
aphasia or dysphasia are related to non-hemorrhagic dAVF
[30–35]. In MRI white matter edema in deep cerebellar or cerebral
hemispheres is a direct evidence of venous congestion and correlates with neurological deficits [36]. Due to their rapid decline
and excellent post-treatment improvement [13,26,28,37], rapid
evaluation and treatment of dAVF is required. We describe a case
of a patient with a tentorial fistula, with a high arterial flow, draining into the straight sinus with occlusive changes of the straight
sinus resulting in sinus thrombosis and venous reflux during the
course. The impaired hemodynamic conditions led to venous congestions, bithalamic edema, and microbleedings. The patient experienced a rapidly progressive confusion, similar to thalamic
dementia with memory deficits and mild aphasia within a few
days prior to treatment. After interdisciplinary case discussion,
microsurgery was performed. Beside the dilemma of medical
anticoagulative treatment of the sinus thrombosis despite the
microbleedings, the surgical management is more challenging
too, due to the deep location and vast anastomotic network.
Fig. 4 illustrates the extent of venous congestion and its regression
after treatment. The association of a thrombophilic condition of
hypercoagulopathy in the pathogenesis of dAVF were published
already [17,38–40]. In our report there were no findings considering thrombophilic risk factors.
In their reports Pu et al and Morparia et al described a similar
case of a patient with a parkinsonism due to tentorial dAVF and
acute thrombosis of the straight sinus and lenticular nuclei congestion. The clinical symptoms and hemodynamic MRI findings with
venous congestion were reversible after treatment [12,41]. Our
report also showed a clinical improvement and regression of the
venous congestion after microsurgical clipping of the fistula.
Already in earlier studies the significant impact of thrombophlebitis pattern due to dAVFs with venous congestion as a
prognostic indicator for treatment decisions was pointed out [42].
The most frequent localization of dAVF is the transverse sinus
(50%), followed by the cavernous sinus (16%). These dAVF rarely
cause intracranial hemorrhage. Less common are dAVF of the tentorium (4–12%), but harboring a hemorrage risk of 58% [15,43].
Treatment decision depends on angioarchitectural features, location and clinical presentation. Endovascular embolization, microsurgical interruption or Gamma Knife surgery or the combination
of these treatment methods are common options. Endovascular
treatment has become a first-line treatment for dAVFs during the
past 2 decades and includes transarterial embolization, transvenous embolization or a combination of both, using embolic agents
(polyvinyl alcohol particles, n-butyl-2-cyanoacrylate, Onyx, Coils)
[16,33]. The recurrence rate for a single intraarterial occlusion
may be 50% including a high bleeding risk. The success rate can
be improved by a combined arterial and venous occlusion. However, the transvenous procedure is more risky, as serious obstruction of venous drainage may occur or in the event of incomplete
embolization, cortical reflux may be exacerbated [43]. Endovascular treatment is also an effective procedure in cases of anterior cranial fossa dAVFs. The fistula point can be completely obliterated
with low risk and good results [44]. In dAVF of the tentorium with

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N. Dinc et al. / Journal of Clinical Neuroscience 68 (2019) 317–321

Fig. 3. Intraoperative images Intraoperative images pre- (A, B) and postclipping (C, D) of infratentorial dAVF.

Fig. 4. MRI series preoperative and in early follow up MRI follow up reveals the changes in hemodynamic conditions. Venous congestion with hyperintense regions
bithalamic in FLAIR preoperative (A), in early postoperative MRI follow up (B) and regression 3 months after discharge (C).

feeding arteries from the vertebral artery or internal carotid artery,
a complete or permanent occlusion may be rarely possible due to
recanalization of small arterial feeders. Therefore some authors
argue for primary surgical care [43,45]. Gamma Knife surgery is
recommended for lesions without cortical venous reflux and with
low risk of hemorrhage. The main problem remains the period of
1 to 2 years until a fistula closure can be achieved. Therefore
Gamma Knife surgery in hemorrhagic dAVF is indicated only in
exceptional cases.
In our case, surgery was preferred for the occlusion of the
infratentorial dAVF. The access to this deep-seated fistula and
post-treatment results including fistula closure and cognitive
function were excellent.
Cognitive impairment due to venous hypertension and
venous congestion is an underrecognized symptom and literature

therefore is limited to case reports. The aim of our report is to
emphasize hemodynamic features of a rare subtype of dAVF with
its presenting symptoms, treatability and rapid radiographic resolution and neurological improvement after treatment.

5. Conclusion
Management of tentorial dAVFs is challenging and requires
carefully planning, especially the association with sinus thrombosis may lead to neurological deficits due to venous congestions in
deep brain regions and harbor a high risk of intracerebral hemorrhage. These findings and the knowledge about the reversibility
of the symptoms with a favorable outcome after treatment are
essential impact factors for treatment decisions.

N. Dinc et al. / Journal of Clinical Neuroscience 68 (2019) 317–321

Ethical approval
The study was approved by the ethics standard of our institution and was reviewed and approved by the local ethics committee.
Patient consent was obtained.
Conflict of interest
All authors certify that they have NO affiliations with or
involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock
ownership, or other equity interest; and expert testimony or
patent-licensing arrangements), or non-financial interest (such as
personal or professional relationships, affiliations, knowledge or
beliefs) in the subject matter or materials discussed in this
manuscript.
Funding
No funding was received for this research.
Acknowledgment
The authors thank Marina Heibel, Department of Neurosurgery
for her excellent technical support.
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