JMV—Journal de Médecine Vasculaire (2020) 45, 62—66

Available online at

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ORIGINAL ARTICLE

Basilar artery fenestration and ischemic
stroke: An unclear causal relationship夽
H. El Otmani ∗, V. Fotso , B. El Moutawakil , M.A. Rafai
Department of neurology-neurophysiology, IBN Rochd university health center, Casablanca, Morocco
Received 3 August 2019; accepted 31 December 2019
Available online 12 March 2020

KEYWORDS
Basilar artery
fenestration;
Basilar artery
duplication;
Ischemic stroke

Summary Basilar artery fenestration is the second most commonly observed fenestration of
the cerebral arteries. In addition to our case, we reviewed the clinical, imaging findings, treatment, and prognosis of 9 other reported cases. Patients’ mean age was 45.1 years. Half of them
had cardiovascular risk factors. Mean time to diagnosis was 9.4 days. The main symptoms were
right hemiparesis and dysarthria. Basilar artery fenestration was found in all patients, as well
as ours, in addition to a thrombus, found in 2 cases. One patient was treated by IV thrombolysis
and thrombectomy. In other cases, antiplatelet drugs or anticoagulants were used. A favorable
outcome was observed in most cases with one reported death.
© 2020 Elsevier Masson SAS. All rights reserved.

Introduction
Basilar artery (BA) fenestration, defined as a segmental
duplication, is a developmental abnormality due to aberrant fusion of the primitive longitudinal neural arteries in
the fifth week of fetal life [1,2]. Cerebral artery fenestration was reported with the frequency of approximately 23%

Abbreviations: BA, Basilar Artery; MRI, Magnetic Resonance
Imaging; MRA, Magnetic Resonance Angiography; CTA, Computed
Tomography Angiography; AHT, Arterial Hypertension; AICA, Anterior Inferior Cerebellar Artery.
夽 This work was presented as a poster at the Maghrebian congress
of neurology, 2018, December 13—15, Marrakech, Morocco.
∗ Corresponding author.
E-mail address: hichamotmani@hotmail.com (H. El Otmani).
https://doi.org/10.1016/j.jdmv.2020.01.147
2542-4513/© 2020 Elsevier Masson SAS. All rights reserved.

in the anterior circulation and 7% in the posterior circulation
[3]. BA fenestration is the second most reported fenestration of the cerebral arteries [4]. This variant may predispose
to aneurysm formation and subarachnoid hemorrhage, dissection or thromboembolic events [5,6]. Generally, basilar
artery occlusion is due to atherosclerosis with a superimposed thrombosis [5]. Therefore, the causal relationship
between this anatomic variant and cerebral events is unclear
and controversial. Here we report a case of symptomatic BA
fenestration revealed by a brainstem infarction and review
other published reports in the literature.

Observation
A 33-year-old Ivorian male, with a smoking history, presented with sudden onset of vertigo, tingling of the

Basilar artery fenestration and ischemic stroke

63

Figure 1 A. Diffusion-weighted MR imaging showing high signal intensity in the left pontine area: recent ischemic lesion. B. MRA:
BA fenestration (red arrow). C. CTA: BA fenestration (orange arrow). D. Normal aspect: the primitive longitudinal neural arteries
merge (dashed area) to form the basilar artery. Basilar artery fenestration: partial fusion of these arteries (blue arrow). D. PCOM:
posterior communicating arteries PICA: posterior inferior cerebellar arteriesAICA: anterior inferior cerebellar arteries SCA: superior
cerebellar arteries.

left hemiface, diplopia and speech difficulties. His condition worsened 2 hours later by an acute onset of
right-sided paresis. Neurological examination showed rightsided hemiparesis with left facial palsy and dysarthria
(National Institutes of Health Stroke Scale (NIHSS): 8/42);
mRs = 4. Diffusion-weighted magnetic resonance imaging
(MRI) revealed a hypersignal in the left pontine area,
compatible with an ischemic lesion (Fig. 1A). Magnetic
resonance angiography (MRA), using time-of-flight technique, displayed a focal signal intensity loss within the
basilar artery (Fig. 1B). This was confirmed by Computed
tomography angiogram (CTA) which also showed no dissection (Fig. 1C). A complete etiological assessment; lipid
panel, biological and, especially, cardiac workout (24-hour
Holter electrocardiogram, transthoracic echocardiogram
and supra-aortic trunks ultrasound) were all normal. Blood
cell count didn’t show signs of anemia or sickle cell disease.
According to these findings, diagnosis of an acute thromboembolic brainstem infarction due to BA fenestration was
suspected. The patient was treated with an antiplatelet drug
(aspirin 100 mg daily) as well as motor rehabilitation, for
six months, with a notably favorable outcome at 3 months
(mRs = 1 vs. 4).

Material and methods
We performed a literature review of MEDLINE, Science
Direct and Google Scholar databases for articles published
in English or French from December 1987 to December
2018 using the search terms ‘‘basilar artery fenestration,’’
and ‘‘basilar artery duplication.’’ We also examined all
manuscripts that had been referred in these articles. We
finally included symptomatic cases of BA fenestration in the
form of infarction. We excluded cases without infarction and
articles not written in English or French. We added our case
to 9 other published reports of symptomatic BA fenestration
(Table 1).

Results
Symptomatic cases
The symptomatic cases are:
• characteristics of the study population (10 cases):
patients’ mean age was 45.1 years (range, 5 to 76 years);

64

Table 1

Cases of ischemic stroke secondary to basilar artery fenestration.

Case reports

Age/Gender

Background/
Mean time
to diagnosis

Symptoms

Our case

33/M

Tobacco/3
days

Right hemiparesis,
dysarthria

Mei nel et al. [7]

76/M

Scherer et al. [4]

69/M

Gold et al. [1]

12/M

AHT,
OSA, Dyslipidemia/90 min
AHT,
Diabetes,
Dyslipidemia/3
days
/1 day

S. He et al. [3]

28/M

Woo et al. [2]

55/F

Kloska et al. [10]

05/M

Palazzo et al. [8]

Vessels

Therapy

Outcome

MRI/MRA/CTA Left pontine
ischemia

BA
fenestration

Good

Right hemiparesis,
hemiataxia,
dysarthria
Right hemiparesis,
dysarthria,
dysphagia

MRI/MRA/
Angiography

Left pontine
ischemia

MRI/MRA/
Virtual
endoscopy

Left pontine
ischemia

BA fenestration/
Thrombus
BA
fenestration

Trombocytes
agrégation
inhibitors
IV thrombolysis/
thrombectomy

Right hemiparesis,
dysmetria

MRI/MRA/
Angiography

Bilateral
cerebellar
ischemia

/1 month

Numbness of limbs

CTA

AHT,
Diabetes/1
day
/3 weeks

Right hemiparesis
+ facial palsy,
dysarthria
Headache,
dizziness, severe
somnolence

59/M

AHT/3
weeks

Berry et al. [5]

43/M

/2 weeks

Dysarthria, left
dysmetria, right
superior
quadrantanopia
Eyesight,
headache, status
epilpticus

Uchiyama et al. [9]

71/M

AHT/1 day

Imaging
technique

Parenchyma

MRI/MRA/
virtual
Endoscopy
Apolipoprotein MRI/MRA
(a) and heterozygotic
factor XII
deficiency
Normal
MRI/MRA/CTA

Left pontine
ischemia

CT/MRI/Auto
psy

Increased
T2-weighted
image in the
pons
Multiples
lacunae +
atrophy

Hyperuricemia CT/
Angiography

Left
paramedian
pons and
the left PCA
ischemia
Left PCA +
cerebellar
infarction

BA
fenestration
BA
fenestration
+ moya
moya
BA
fenestration

Heparin/
trombocytes
agrégation
inhibitors
Aspirin

Heparin

BA
fenestration
or thrombus

Trombocytes
agrégation
inhibitors

BA
fenestration

Good

Heparin/clopidogrel Good

Proximal BA
fenestration

BA fenestration/
Thrombus

NIHSS = 0

Good

Death

H. El Otmani et al.

Unsteady gait,
dysarthria,
diplopia

Etiological
assesment

Basilar artery fenestration and ischemic stroke
included 9 men (90%). Half of them had cardiovascular risk
factors (5 patients): hypertension was found in 5 patients
(50%) [2,4,7—9], diabetes in 2 patients (20%) [2,4], dyslipidemia in 2 patients (20%) [4,7], obstructive sleep apnea
and overweight in 1 patient (10%) [7]. Our patient’s smoking habit was stopped 7 years earlier. The mean time to
diagnosis was 9.4 days; the main symptoms were right
hemiparesis and dysarthria [1,2,4,7];
• imaging results: ischemic stroke was found in the basilar
artery territory, except one patient with multiple lacunae
and atrophy. There was no hemorrhagic transformation.
The BA fenestration was found in all patients as well as
ours with an associated thrombus, suspected in one case
[8] and confirmed in 2 cases [5,7]. There was no aneurysm
nor dissection;
• etiological assessment: found, essentially, apolipoprotein(a) and heterozygotic factor XII deficiency [10].
Concerning the other cases, no abnormality was noted in
the etiological assessment, especially the cardiac workout;
• treatment: one patient was treated by IV thrombolysis and
thrombectomy. In the other cases, antiplatelet agents or
heparin were used in addition to physiotherapy;
• outcome: almost all cases have seen their symptoms
improved except for one notified death.

Discussion
Patients’ mean age was 45.1 years; this age of occurrence is
younger than that seen in all 5657 sequential cerebral CTA
of patients analyzed by Gao et al. (mean age, 54.3 years)
[6].
Fenestration in the cerebrovascular system (particularly
the vertebral arteries) was first detected, on autopsy, in
1866. Since then, many cases have been documented [6].
The incidence of BA fenestration varies from 0.3% in angiographic examinations to 5.26% in the autopsy series [2,7].
There are two types of cerebral arteries fenestrations: true
duplications, which have a relatively large arterial window,
and arterial slits, which are considered to be intraluminal
defects [2,4]. Fenestration is referred to the localized duplication of a vessel [2] (Fig. 1D).

Diagnosis
CTA can be helpful, in addition to MRA, for diagnosis. But
both have pitfalls in the diagnosis of intracranial vascular
disease [8]. Therefore, virtual endoscopy may be useful in
some cases in combination with conventional techniques [4].
CTA was performed in our patient confirming a diagnosis
of BA fenestration already suspected in MRA. The proximal
end of the basilar artery, at vertebral arteries convergence,
seems the most prone to fenestration [1,2]. BA fenestration
is classified into 4 types according to its location and the
AICA’s origin (anterior inferior cerebellar artery) [6].

Other associated malformations
Fenestrations of cerebral arteries can be multiple [4].
The formation of saccular aneurysm is the most common

65
complication [1]. Gao et al. reported 34 cases of aneurysms
in 132 cases of BA fenestration from a total of 5657 CTAs [6].
In addition, it can be associated with cerebral arteriovenous
malformation, persistent trigeminal artery [4], Moya Moya
disease and azygos anterior cerebral artery [3,6]. There was
no associated vascular abnormality in our case as shown by
CTA.

Pathophysiology
An association of cerebral artery fenestration with a subarachnoid hemorrhage is more frequently reported than an
ischemic event. In general, when BA fenestration is symptomatic; it results in a subarachnoid hemorrhage due to a
saccular aneurysm rupture [9]. Because BA fenestration is
uncommon and is usually an incidental product on autopsy or
angiography [3,9]; little is known about it’s functional consequences [1]. In addition, its clinical significance remains
controversial. However, there is a defect in the media of the
arterial wall with turbulent blood flow and hemodynamic
disturbances at the fenestration site that could explain the
formation of thrombi and consequently the occurrence of
ischemic stroke [2,5,6,10]. Gold et al. hypothesized this
to be the cause of stroke in their patient [1]. We assume
that it was the case in our patient. Aneurysm formation can
be explained by the same mechanism [2,3]. To date, only
a few case reports presume a causal association between
brainstem infarction and basilar artery fenestration [10];
these cases are reported here (Table 1). If an AICA arises
from the thrombosed fenestrated segment of the BA, both
pontine and cerebellar infarctions may develop [1,8]. A misinterpretation of BA fenestration as an arterial dissection
or thrombosis, especially in patients with stroke, can result
in wrong diagnostic, and thus therapeutic, approaches. Its
management is more or less aggressive depending on the
case [4].

Conclusion
Our literature review and case report showed that 75% of
patients with ischemic stroke due to BA fenestration have
a pontine paramedian involvement. Therefore, such location in a patient without vascular risk factors (in particular
atherosclerosis) should suggest this diagnosis.
Our patient presented with a suspected symptomatic BA
fenestration as there was a corollary between the brainstem
infarction location and that of the vascular abnormality with
a negative etiological assessment otherwise.

Disclosure of interest
The authors declare that they have no competing interest.

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