Treatment of Extracranial Dissecting Pseudoaneurysms with Flow Diverters: A Single Center Experience

Abstract

Purpose: Flow Diverters (FD) have immensely extended the treatment of cerebral aneurysms in the past decade. Despite the growing experience, treatment of extracranial dissection Pseudoaneurysms (PA) remains an off-label use and is limited to small case series in literature.
Methods: Fourteen patients with 15 dissecting PA of the extracranial Internal Carotid Artery (ICA) and vertebral artery who were treated with FDs between 2011 and 2018 were examined retrospectively. Aneurysm occlusion, procedural complications, and clinical outcome were evaluated.
Results: Angiographic follow-up was available for all patients with a mean long-term follow-up time of 17.4 ± 14.5 months. Aneurysms were located in the anterior (86.7%, n=13) and posterior (13.3%, n=2) circulation. Of the ICA, the C1 segment was predominant (53.3%, n=8). Aneurysm morphology was saccular (86.7%, n=13) and fusiform (13.3%, n=2). Adequate aneurysm occlusion (Kamran grade 3 and 4) at long-term follow-up was achieved in 93.3% (n=14). Symptoms of patients were: Headache (42.9%, n=6); Stroke (21.4%, n=3); Horner’s-Syndrome (7.1%, n=1); Vertigo (7.1%, n=1). Reported etiologies were spontaneous (71.4%, n=10), traumatic (21.4%, n=3) and iatrogenic (7.1%, n=1). Underlying dissecting stenosis was observed in 21.4% (n=3) with a mean of 69.1 ± 16.8% and decreased significantly at long-term follow-up (12.1 ± 21.0%; p=0.022). Asymptomatic thromboembolic event occurred in 7.1% (n=1). Retreatment was performed in 7.1% (n=1). There was no procedural morbidity or mortality.
Conclusion: Treatment of extracranial dissection pseudoaneurysms using FDs is effective and safe. Further studies with larger case numbers are necessary to establish this treatment method in selected patients.

Full text

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Abbreviations
PA: Pseudoaneurysms; CeAD: Cervical Artery Dissection; FD: Flow Diverters; DSA: Digital
Subtraction Angiography; DED: Derivo Embolization Device; PED: Pipeline Embolization Device;
FRED: Flow Redirection Endoluminal Device; p64 FMD: p64 Flow Modulation Device; ISS: In-
Stent-Stenosis; DAPT: Dual Antiplatelet erapy; ICA: Internal Carotid Artery; VA: Vertebral
Artery
Introduction
Cervical Artery Dissection (CeAD) of the internal carotid arteries and vertebral arteries is a
common cause of stroke in young and middle-aged people and results in ischemic events between
8 and 25% in patients <45 years of age [1]. CeAD is caused by a rupture of vascular layers with
or without an identiable environmental trigger or underlying vascular disease leading to an
arterial wall hemorrhage. Based on the imaging, dissections are classied as follows: Occlusive,
pseudoaneurysmal and stenotic [2]. e etiology of CeAD is usually spontaneous, followed by
a traumatic or iatrogenic etiology [3]. e low incidence of CeAD between 3.5 to 2.5 per 100.00
has made it dicult to establish a clear management strategy [4-6]. First line treatment nowadays
includes early anticoagulation or antiplatelet therapy which leads to a recanalization rate of 50%
to 70% and resolution of symptoms [2,7,8]. However, endovascular treatment may be required in
patients at high risk of bleeding or persistent, progressive, and recurring neurological symptoms
during conservative therapy. Until today the literature is limited to case reports and systematic
Treatment of Extracranial Dissecting Pseudoaneurysms
with Flow Diverters: A Single Center Experience
OPEN ACCESS
*Correspondence:
Andreas Simgen, Department of
Neuroradiology, Saarland University
Hospital, Kirrberger Str. 1, D-66424
Homburg/Saar, Germany, Tel: 0049-
6841-1624302; Fax: 0049-6841-
1624310;
E-mail: andreassimgen@googlemail.
com
Received Date: 10 Jan 2022
Accepted Date: 20 Feb 2022
Published Date: 10 Mar 2022
Citation:
Simgen A, Yilmaz U, Roth C,
Papanagiotou P, Dietrich P, Mühl-
Benninghaus R, et al. Treatment
of Extracranial Dissecting
Pseudoaneurysms with Flow Diverters:
A Single Center Experience. Clin Surg.
2022; 7: 3440.
Copyright © 2022 Andreas Simgen.
This is an open access article
distributed under the Creative
Commons Attribution License, which
permits unrestricted use, distribution,
and reproduction in any medium,
provided the original work is properly
cited.
Research Article
Published: 10 Mar, 2022
Abstract
Purpose: Flow Diverters (FD) have immensely extended the treatment of cerebral aneurysms in the
past decade. Despite the growing experience, treatment of extracranial dissection Pseudoaneurysms
(PA) remains an o-label use and is limited to small case series in literature.
Methods: Fourteen patients with 15 dissecting PA of the extracranial Internal Carotid Artery
(ICA) and vertebral artery who were treated with FDs between 2011 and 2018 were examined
retrospectively. Aneurysm occlusion, procedural complications, and clinical outcome were
evaluated.
Results: Angiographic follow-up was available for all patients with a mean long-term follow-up
time of 17.4 ± 14.5 months. Aneurysms were located in the anterior (86.7%, n=13) and posterior
(13.3%, n=2) circulation. Of the ICA, the C1 segment was predominant (53.3%, n=8). Aneurysm
morphology was saccular (86.7%, n=13) and fusiform (13.3%, n=2). Adequate aneurysm occlusion
(Kamran grade 3 and 4) at long-term follow-up was achieved in 93.3% (n=14). Symptoms of patients
were: Headache (42.9%, n=6); Stroke (21.4%, n=3); Horner’s-Syndrome (7.1%, n=1); Vertigo (7.1%,
n=1). Reported etiologies were spontaneous (71.4%, n=10), traumatic (21.4%, n=3) and iatrogenic
(7.1%, n=1). Underlying dissecting stenosis was observed in 21.4% (n=3) with a mean of 69.1 ±
16.8% and decreased signicantly at long-term follow-up (12.1 ± 21.0%; p=0.022). Asymptomatic
thromboembolic event occurred in 7.1% (n=1). Retreatment was performed in 7.1% (n=1). ere
was no procedural morbidity or mortality.
Conclusion: Treatment of extracranial dissection pseudoaneurysms using FDs is eective and
safe. Further studies with larger case numbers are necessary to establish this treatment method in
selected patients.
Keywords: Flow Diverter; Pseudoaneurysms; PED; DED; FRED; p64; SILK
Andreas Simgen*, Umut Yilmaz, Christian Roth, Panagiotis Papanagiotou, Philipp Dietrich,
Ruben Mühl-Benninghaus, Wolfgang Reith and Michael Kettner
Department of Neuroradiology, Saarland University Hospital, Homburg/Saar, Germany

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reviews, which have shown endovascular treatment of dissecting PA
of the anterior and posterior circulation using a variety of extracranial
stent systems with or without additional coiling [2,9-11], intracranial
stent systems [12,13] and Flow Diverters [10,11,14,15]. For the
treatment of CeAD with FDs, even fewer and smaller cases, have
been reported in the literature, mainly with rst generation devices
(Pipeline Embolization Device; PED, Medtronic Inc., Minneapolis,
Minnesota, USA and the SILK Flow Diverter, SFD, Balt Extrusion,
Montmorency, France) showing good angiographic and clinical
results [10,11]. Due to the fact that FDs have become a standard
treatment option for intracranial aneurysms with promising results
[16] and those more complex aneurysms are much easier to treat
compared to early methods such as surgical reconstruction or ligation
of the patent vessel, further research should be sought in this o-label
use of FDs.
e purpose of this retrospective analysis was to share our
experience in treating extracranial dissecting pseudoaneurysms of
the ICA and VA with dierent FDs. To the best of our knowledge,
this is the rst study to report on the treatment of PAs with other
ow diverters (Flow Redirection Endoluminal Device (FRED;
MicroVention, Tustin, CA, USA), p64 Flow Modulation Device (p64;
Phenox GmbH, Bochum, Germany) and Derivo Embolization Device
(DED; Acandis, Pforzheim, Germany) in addition to the PED and
SILK.
Material and Methods
Patient selection
Ethics committee approval was obtained for this retrospective
data analysis. We analyzed our database and screened for patients
with extracranial pseudoaneurysms of the ICA and VA treated with
ow diverters between January 2011 and December 2018. DSA or
Magnetic Resonance Angiography (MRA) was required at st follow-
up (3 to 6 months) and nal follow-up (>6 months). Aneurysms
additionally treated with coil embolization were also included.
Antiplatelet management and endovascular procedure
All patients received a Dual Antiplatelet erapy (DAPT) of 100
mg acetylsalicylic acid and clopidogrel 75 mg daily at least 3 days prior
to the intervention. Periprocedural a dose of 3000 IU i.v. heparin was
administered. DAPT was continued for at least 3 months aer the
procedure and aspirin indenitely thereaer. Platelet function testing
was not performed since its level of evidence remains controversial
[17].
Procedures were performed through femoral access under general
anesthesia using either a biplane angiography machine (Axiom Artis;
Siemens Healthcare, Munich, Germany) (from 2011 until 2014) or
a biplane at panel detector angiographic system (Artis Q; Siemens
AG, Erlangen, Germany) (form 2014 until 2018). e imaging was
performed in posterior-anterior and lateral projection (2D-DSA
series) with a frame rate of 2 to 4 frames/s and in the working
position. A total of 5 dierent FDs were used for aneurysm treatment
in this study; Pipeline Embolization Device (PED; Medtronic Inc.,
Minneapolis, Minnesota, USA), SILK Flow Diverter (SFD; Balt
Extrusion, Montmorency, France), Flow Redirection Endoluminal
Device (FRED; MicroVention, Tustin, CA, USA), p64 Flow
Modulation Device (p64; Phenox GmbH, Bochum, Germany) and
Derivo Embolization Device (DED; Acandis, Pforzheim, Germany).
e type of FDs used to treat the aneurysm was at the discretion
of the treating physician. e sizing of the FDs was based on the
maximum diameter of the parent vessel into which the FDs were to be
implanted. e length of the implanted FD was selected based on the
width of the aneurysm neck to be covered and the underlying vascular
course. All devices were delivered using a 0.027-inch microcatheter
via a bi- or triaxial approach in a standard deployment technique.
First, the microcatheter was placed distal to the aneurysm neck and
then the FD was inserted into the microcatheter. In cases in which
additional coiling was performed a second 0.017-inch microcatheter
(Echelon-10, Medronic, Duplin, Ireland) was placed in the aneurysm
in jailing-technique. e placement of the FD was achieved by a
combination of withdrawing the microcatheter and gently holding/
pushing the delivery wire of the FD in place of the desired destination.
Angiographic evaluation
Aneurysm occlusion was assessed using a ve-point scale
previously described in literature [18] as follows: Grade 0, no endo-
aneurysmal ow changes; grade 1, residual lling >50%; grade 2,
residual lling <50%; grade 3, near complete occlusion with residual
lling at the aneurysm neck; grade 4, complete occlusion. Aneurysms
showing grade III and IV were classied as adequately occluded.
Dissecting stenosis was assessed using the minimum lumen diameter
in relation to the normal diameter of the parent vessel distal to the
located stenosis. e stenosis was classied as follows low-grade
(<50%), moderate (50% to 75%) and high-grade (>75%). e patency
of the parent artery and the covered side branches were also assessed.
Clinical outcome evaluation
Clinical outcome was evaluated preinterventionally, at discharge
and at follow-up using the modied Rankin scale. Good clinical
outcome was classied as a mRS 0-2. Treatment-related morbidity
was classied as a mRS 3-5.
Statistics
Continuous variables are expressed as means ± standard
deviations. Categorical variables are presented as frequencies and
percentage, unless stated otherwise. Analyses were performed using
Fisher’s exact and χ2 tests. Statistical signicance was accepted at a
two-sided p value of <0.05. All data analyses were performed using
SPSS Statistics 25TM (IBM Inc., Chicago, IL, USA).
Results
Patient and aneurysm characteristics
Fourteen patients with 15 extracranial PAs treated with FD
implantation in our department were retrospectively analyzed. From
our collective all patients were available for follow-up (9 women
and 5 men). 86.7% of the aneurysms were located in the anterior
and 13.3% in the posterior circulation. According to the Bouthillier
classication of the ICA most aneurysms (53.3%) were located in
the C1 segment. Both PA treated in the posterior circulation were
located in the V2-Segment of the VA. 86.7% of the aneurysms treated
in this study were saccular and 13.3% fusiform in morphology. Of
the ow diverters available on the market, ve were used to treat
the aneurysms. Seven patients (50%) were treated with a PED, three
patients (21.5%) with a FRED, two patients (14.3%) with a DED, one
patient (7.1%) with a SILK and one patient (7.1%) with a p64. Most
of the saccular aneurysms treated in this study were narrow-necked.
Telescoping with multiple FDs was performed in 4 patients (28.6%).
One patient was treated with two DEDs, another patient with 2
PEDs. ree FREDs were implanted in one patient and in the last
patient 4 FREDs have been used. Additional coiling was performed
in 2 patients (13.3%). On average, the patients in this study received

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a DAPT of 8.0 ± 6.3 months (median 6 months). Demographic data,
aneurysm location and morphology are presented in detail in Table 1.
Table 2 shows details of the interventional procedures for all patients.
Angiographic follow-up
First follow-up was performed aer 4.9 ± 2.5 months (median 4)
and available as DSA in 12 patients (85.7%) and as MRA in 2 patients
(14.3%). Final follow-up was performed aer 17.4 ± 14.5 months
(median 14.5) and available as DSA in 10 patients (71.4%) and as
MRA in 4 patients (28.6%). At rst follow-up 11 aneurysms (73.3%)
showed complete occlusion (Kamran grade 4), two aneurysms
(13.3%) showed residual lling at the aneurysm neck (Kamran grade
3), one aneurysm (6.7%) revealed residual lling <50% (Kamran
grade 2) and one aneurysm (6.7%) revealed residual lling >50%
(Kamran grade 1). Respectively, leading to an adequate aneurysm
occlusion (Kamran grade 3 and 4) of 13 aneurysms (86.7%) (Figure
1). At nal follow-up 13 aneurysms (86.7%) showed complete
occlusion (Kamran grade 4), one aneurysm (6.7%) had residual
lling at the aneurysm neck (Kamran grade 3, Figure 2h) and one
aneurysm (6.7%) revealed residual lling <50% (Kamran grade 2).
Respectively, leading to an adequate aneurysm occlusion (Kamran
grade 3 and 4) of 14 aneurysms (93.3%). Comparison of adequately
occluded aneurysms (Kamran grade 3 and 4) at both follow-up
periods revealed no signicant dierences (p=0.469). In one patient,
a fusiform PA of the right ICA was treated with 4 telescopic FREDs,
whereby only a marginal overlap of the proximal aneurysm was
achieved, which led to inadequate aneurysm occlusion (Kamran
grade 2) at the nal follow-up aer 10 months. Retreatment in this
case was recommended but never carried out because the patients
decided to seek a second opinion in another hospital.
ree patients (21.4%) had an underlying dissecting stenosis with
a mean of 69.1 ± 16.8%. Treatment was performed in all cases using
a PED. Immediately aer implantation of the FDs the stenosis was
already decreasing with a mean of 44.9 ± 18.3%. Immediately aer
implantation of the FDs, the stenosis had already decreased with a
mean of 44.9 ± 18.3%. At long-term follow-up 11.0 ± 10.4 months
the stenoses decreased signicantly with a mean of 12.1 ± 21.0% and
a p-value of 0.022.
Clinical characteristics
A traumatic history could be determined in three patients
(21.4%). One patient suered blunt head trauma in a brawl, one
patient suered penetrating neck trauma aer a bicycle accident,
and the last patient was involved in a car accident. Of these patients
two were clinically asymptomatic and one patient presented with a
stroke. Overall, three patients (21.4%) presented with minor strokes,
most likely caused by the PAs located in the same vascular areas. Two
of these PAs were located at the ICA (C1 and C2-segment) and the
other at the VA (V2-segment). Symptoms caused by the PAs were
hemihypesthesia (C1-segment PA) and vertigo (V2-segment PA).
e C2-segment PA was caused iatrogenic ally during treatment of
an intracranial aneurysm three months earlier. During the follow-
up, the PA was noted and small acute punctiform infarcts were
observed on Magnetic Resonance Imaging (MRI). e patient did
not show any neurological symptoms. In total 6 Patients (42.9%)
presented with headaches, 1 patient (7.1%) vertigo and 1 patient
(7.1%) with Horner’s-Syndrome. Overall, 7 patients (50%) presented
with no neurological symptoms. Details of the treatment and clinical
characteristic are presented in Table 2.
12 (85.7%) patients entered this study with mRS 0 and two patients
(14.3%) with mRS 1. Pre-interventional mRS 1 was caused by vertigo
due to small embolic infarctions from a V2-Segment pseudoaneurysm
of the VA in one patient. e other patient presented with Horner's
syndrome and hemi hypesthesia due to a growing pseudoaneurysm
of the le ICA (C1 segment) aer blunt head trauma with small
embolic middle cerebral artery infarctions. No changes in the mRS
were observed aer the intervention or at discharge. At rst follow-
up 13 (92.9%) patients presented with mRS 0 and one patient (7.1%)
with mRS 1 due to a residual Horner’s syndrome. At nal follow-up
all patients presented with mRS 0. Overall, there was no treatment-
related morbidity or mortality.
Complications
In one patient a small pseudoaneurysm of the C1 segment of
the le ICA increased signicantly within a period of two months
ab
cd
Figure 1: Time-of-ight angiography of a pseudoaneurysm (8.6 mm x 6.2 mm × 13.8 mm) arising from the right ICA (C1 segment) (a). DSA shows partially
thrombosed pseudoaneurysm with an underlying dissecting stenosis of 75% (b). DSA immediately after implantation of a PED showing delayed lling of the PA
and improved stenosis of 50% (c). DSA after 6 months showed a complete occlusion of the PA (Kamran 4) and a residual stenosis of approximately 30% (d).

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aer blunt neck trauma into a giant pseudoaneurysm (33.3 mm ×
19.1 mm × 18.2 mm) (Figure 2a, 2b) and caused minor stroke. Initial
treatment was performed with a PED and additional coiling (Figure
2c). First follow-up revealed a distinct proximal foreshortening with
partial dislocation of the PED into the aneurysm and inadequate
aneurysm occlusion (Kamran grade 1) (Figure 2d). Retreatment was
performed aer successful navigation through the dislocated PED by
implantation of a low-prole intracranial stent (Acclino Flex, Acandis,
Pforzheim, Germany) to ensure vascular access (Figure 2e). Aer that
the residual pseudoaneurysm was treated by implantation of another
FD (DED) and additional coiling in jailing-technique (Figure 2f, 2g).
Post-interventional MRI of this patient revealed a punctate middle
cerebral artery infarction without neurological symptoms. One
other patient suered a peri-interventional occlusion of a peripheral
parietal branch of the middle cerebral artery aer treatment of a right
C2-segment ICA PA. e occlusion was completely recanalized by
administration of 15 mg i.v. thrombolysis (Actilyse, Boehringer,
Ingelheim, Germany). e patient had no clinical symptoms.
Overall, we observed one ischemic event (7.1%) without clinical
sequelae, one retreatment (7.1%) aer foreshortening at follow-up.
In-Stent-Stenosis (ISS) was seen in 4 patients (28.6%) at rst
follow-up (1 PED, 1 DED and 2 FRED) compared to 1 remaining
stenosis (7.1%) at last follow-up (1 FRED). ISS was mild overall (15.5
± 6.7%) and decreased at last follow-up (2.7% ± 5.4%).
We observed no peri-interventional bleeding, delayed aneurysm
a
h
bc d
ef g
Figure 2: CT-Angiography and DSA of a pseudoaneurysm of the C1 segment of the left ICA with signicant growth (33.3 mm × 19.1 mm × 18.2 mm) within two
months after blunt neck trauma (a and b). DSA after treatment with a PED and additional coiling (c). DSA after 6 months revealed inadequate aneurysm occlusion
(Kamran grade 1) due to a proximal foreshortening of the PED with partial dislocation into the aneurysm (d). Fluoroscopy after retreatment with a low-prole
intracranial stent (Acclino Flex, Acandis, Pforzheim, Germany) to ensure vascular access (e). Fluoroscopy and DSA after implantation of another FD (DED) and
additional coiling (f and g). MR-Angiography 12 months after retreatment showed a near-complete occlusion of the PA (Kamran grade 3, green arrow) (h).
a
d
b
c
Figure 3: Overall, we observed one ischemic event (7.1%) without clinical sequelae, one retreatment (7.1%) after foreshortening at follow-up.

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rupture or occlusion of the implanted FDs. ere was no procedural
morbidity or mortality (Figure 3).
Discussion
CeAD accounts for 8% to 25% of strokes in young patients
and is the leading cause of stroke in patients <45 years of age [1].
e manifestation of CeAD occurs stenotic in 47%, stenotic in
combination with a PA in 28%, occlusive in 18% and as a PA alone in
7%. us, one third of the patients with CeAD develop a PA [4,19].
e recurrence rate of ischemic stroke aer symptomatic dissection of
the ICA and VA varies between 2% to 30% in the literature [2,20-22].
Medical management with anticoagulation or platelet inhibition for 3
to 6 months is the therapy of choice today and leads to good clinical
outcomes in most patients. However, the superiority of one of the
two drugs has not yet been proven [2,7,8,23]. Endovascular treatment
should be considered for selected patients with failure of medical
therapy such as new ischemic events, worsening of neurological
symptoms and enlargement of PA [9].
e purpose of this retrospective study was to share our
experience in treating extracranial dissecting pseudoaneurysm using
dierent FDs.
CeAD aects the ICA more oen than the VA and is mostly
spontaneous, followed by trauma or iatrogenic events [2,3]. In our
study etiology of CeAD was spontaneous in 10 patients (71.4%),
traumatic in three patients (21.4%) and iatrogenic in one patient
(7.1%). Of the traumatic events observed in our study, 2 were blunt
and one was penetrating trauma. Iatrogenic etiology of PA was due
to prior endovascular treatment of an intracranial aneurysm. In a
systematic review by Pham et al. in 2011, it appeared that most CeAD
in need of endovascular treatment had a traumatic cause [9]. None of
the PAs treated in our study could be associated with connective tissue
disease. Main symptoms patients presented with in this study were
headache (42.9%, n=6), vertigo (7.1% n=1) and Horner’s-Syndrom
(7.1%, n=1). Compared to the a currently published systematic
review by Texakalidis et al. in 2020, the rate of asymptomatic patients
treated in our study was quite high at 50% [11]. As far as this could
be retrospectively evaluated, these aneurysms were treated on the
basis of a pronounced treatment request by the patients. Treatment
of asymptomatic PAs, however, remains controversial. On the one
hand, there are reports with no evidence of thromboembolic events
or ruptures [24]. On the other hand, authors report combined stroke
Total
Number of patients (n) 14
Number of aneurysms (n) 15
Mean age 49.1 ± 14.3
Median age 52
Age range 25-70
Female/male sex 9/5
Aneurysm location n (%)
Anterior circulation 13 (86.7)
ICA C1 8 (53.3)
ICA C2 2 (13.3)
ICA C3 3 (20.0)
Posterior circulation 2 (13.3)
VA V2-Segment 2 (13.3)
Aneurysm morphology n (%)
Saccular 13 (86.7)
Fusiform 2 (13.3)
aneurysm width [mm] 7.8 ± 3.6
aneurysm height [mm] 10.0 ± 8.6
aneurysm depth [mm] 7.2 ± 3.4
aneurysm neck [mm] 5.1 ± 3.1
Dome-to-neck ratio 1.6 ± 0.4
aneurysm volume [mm3] 570.1 ± 1429.2
Table 1: Demographics, aneurysm location and morphology.
Patient
No. Sex Aneurysm Location# Clinical
present. Aneurysm
morphology Stent Number of FD Coiling DS bevor
FD (%) DS after
FD (%) DS at
FU (%)
1FC3 H saccular DED 1 Y - - -
2FC3 H saccular P64 1 N - - -
3FC3 H/V saccular DED 2 N - - -
4F C1 - saccular SILK 1 N - - -
5F C1 H saccular PED 1 N - - -
6MC2 Sfusiform PED 2 N - - -
7M C1 - saccular FRED 2 N - - -
M C1 saccular FRED 1 N - - -
8F C1 H fusiform FRED 4 N - - -
9M C1 T saccular PED 1 N75.7 59.1 36.4
10 FC2 - saccular PED 1 N - - -
11 F C1 H saccular PED 1 N - - -
12 M C1 HS/S/T saccular PED 1 Y50 24.2 0
13 FV2 T saccular PED 1 N81.6 51.4 0
14 MV2 V/S saccular FRED 1 N - - -
Table 2: Treatment and clinical characteristics.
Note: F: Female; M: Male; H: Headache; V: Vertigo; HS: Horner’s-Syndrome; T : Trauma; S: Stroke; FD: Flow Diverter; Y: Yes; N: No; DS: Dissecting Stenosis; FU:
Follow-Up
#Bouthillier classication

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and death rates of 21% of patients with PAs [25]. Furthermore, PAs
seem to constitute a long-term risk of distal embolic stroke [26-29]. In
our study three patients (21.4%) presented with minor strokes most
likely caused by the underlying PA.
In the past, CeADs were oen treated endovascularly with carotid
stents [2,9,11] or covered-stents [30,31]. Flow diverters have also been
used increasingly for extracranial CeAD treatment in the last decade
with good angiographic and clinical outcome [11,14,15,32,33]. e
rst extracranial ICA PA treated with a FD was reported by Amenta
et al. in 2012 using a PED with successful reconstruction of the vessel
and complete pseudoaneurysm occlusion aer 4 weeks [34]. Reported
the rst case in the literature in 2013 in which two SILK ow diverters
were used to treat a dissecting PA [32]. e rst largest clinical case
series was published by Brzezicki et al. in 2016, when 11 patients
with ICA dissecting PAs were treated with PEDs [35]. A technical
success rate of 100% has been reported. Nine patients were available
aer a mean follow-up time of 5.2 months and showed a complete
pseudoaneurysm occlusion rate of 75%. No ischemic or hemorrhagic
complications occurred [35]. e most recent multicenter evaluation
was carried out by Akinduro et al. in 2020 [36]. 28 PAs were treated
with the PED in 24 patients with a mean follow-up time of 21 months
without any peri-procedural complications. ey achieved complete
and near complete pseudoaneurysm occlusion rates of 89% and
11%, respectively. Reports on treatment of extracranial VA PAs are
limited to a few singular case reports in literature. All reports have
shown technical success rate of 100% and complete pseudoaneurysm
occlusion aer treatment with the PED [37,38]. To date, there have
been no reports of extracranial PAs treated with ow diverters such
as the FRED, p64, or DED.
In our study most patients (50%) were also treated with the PED,
since it was the rst available FD at times. Later patients have also
been treated with the FRED (21.3%), DED (14.3%) and p64 (7.1%).
Overall, the adequate pseudoaneurysm occlusion rate observed
(93.3%) in our study was higher than that of Brzezicki et al. and
comparable to Akinduro et al. as described by both authors, we also
did not experience any treatment-related morbidities. ere was one
ischemic event (7.1%) without clinical sequelae aer retreatment of a
foreshortened PED, which was partially dislocated into the aneurysm
aer initial treatment 6 months before. e observed rate of ischemic
events is in line with normal expectations when using FDs to treat
aneurysms [16]. Overall retreatment was performed in one patient
(7.1%) and was also comparable with the current literature [39].
ree patients (21.4%) also presented with underlying dissecting
stenoses with a mean of 69.1 ± 16.8%. Flow-limiting stenosis (>80%)
alone has been discussed in the literature as a primary treatment
indication for extracranial carotid dissections because of a potential
risk of cerebrovascular accidents or transient ischemic attacks
[35,40]. Two of our cases were in the ICA and one stenosis was
found in the VA. Brzezicki et al. treated 10 patients in their small
case series presenting with a severe stenoses using a PED. In order
to reach full expansion of the PED additional balloon angioplasty
was performed in all cases. ey reached complete revascularization
in 91%; one stenosis with 20% was remaining [35]. In our study no
balloon angioplasty was performed. Stenoses treated with the FDs
improved immediately post-interventionally from 69.1 ± 16.8% to
44.9 ± 18.3%. At long-term follow-up 11.0 ± 10.4 months the stenoses
decreased signicantly with only one remaining stenosis of 36%. e
regression of a dissecting stenosis as a result of the implantation of
a FD was also described by Cohen et al. In their case series, only 3
out of 8 patients had to undergo additional balloon angioplasty, but
most stenoses declined without further manipulation. We believe
that balloon angioplasty aer FD treatment of dissection stenosis
might only be necessary in selected cases, as FDs have sucient radial
force to promote revascularization compared to other neurovascular
stents-systems. Nonetheless, the role of balloon angioplasty aer FD
treatment of dissection stenosis needs further investigation.
Asymptomatic In-Stent Stenosis (ISS) was observed in our study
in 28.6%, was overall mild with a mean of 15.5 ± 6.7% and resolved
with one remaining stenosis of 7.1% at the last follow-up. ISS
occurred only in patients with no underlying dissection stenosis. ISS
aer FD implantation have already been investigated in many studies;
the rate observed in our study corresponds to the rate expected in the
literature (29% to 57%) aer FD treatment [41,42].
Limitations
e main limitations of this study are its retrospective design
and the relatively small number of patients. Due to the small number
of patients treated with the dierent FDs, the prerequisites for an
adequate statistical comparison were not met. Furthermore, we
report the experience of a single center. Availability of large studies
assessing the safety and eciency of FDs for dissecting PAs treatment
remains limited. In addition, there are no reports in the literature of
treating PAs with the FDs used in our study, making it dicult to
compare our results directly.
Conclusion
Our single center experience shows that treatment of extracranial
dissecting pseudoaneurysms using dierent FDs is safe and eective
with high occlusion rates and no treatment-related morbidity. In
addition, underlying dissection stenosis can also be treated by the
implanted FD without the need for balloon angioplasty. However,
because of the small, limited population requiring endovascular
treatment, larger and multicenter studies are needed to determine the
role of FDs in the treatment of dissecting PAs.
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