Objective: We previously suggested that aberrations of the carotid arteries, which may occur when the neck is bent forward, should be considered as new risk factors for ischemic stroke. We analyzed the results of carotid artery ultrasound examination in previous case and control groups, focusing in particular on the atherosclerotic risk factor in stroke, to determine the significance of arterial aberration and its relation to ischemic stroke. Data Sources and Review Methods: We analyzed the original data from our previous 235 casecontrol study patients among those who underwent complete routine cervical ultrasound and had all cholesterol data available. Results: Although plaque was present in the CCA in about one-half of the control group, none had experienced a stroke. At the same time, two-thirds of the case (stroke) patients had plaque in the CCA. This indicates that plaque tends to be a risk for stroke, although the difference between the two groups was not statistically significant. Conclusion: The results of the present analysis indicate that: 1) the degree of atherosclerosis was the same in both the case and control groups, because there were no statistically significant differences between them in cholesterol values; 2) the only difference between the two groups was the aberration of the carotid artery; and 3) aberration of the carotid artery tends to be a risk factor for stroke. The mechanism of cerebral infarction is speculated to be artery-to-artery embolism from the carotid plaque. The aberration of the carotid artery occurs, which triggered by plaque reaching the cerebellum.
Head and neck, Carotid artery,
Aberration, embolism, plaque
Carotid abnormalities (CAs) are found in more
than half of patients with cardiovascular or cerebral
ischemic symptoms who undergo ultrasound
examination. Atherosclerosis, hypertension,
and aging may all play an important role in the
development of CAs, although aging appears more
important than atherosclerosis . On the other hand,
one study suggested that CAs are not important
stroke risk factors . Previous studies mainly focused
on the cervical common carotid artery (CCA) and the
sections of the external and internal carotid arteries
around the CCA bifurcation.
However, aberration of the internal carotid artery
(ICA) sometimes occurs inside the mouth in elderly
patients with bent posture , which is difficult to
diagnose in ultrasound examination. Patients with
asymptomatic carotid artery stenosis who have a
60% or greater reduction in arterial diameter and
whose general health makes them good candidates
for elective surgery will have a lower 5-year risk
of ipsilateral stroke if carotid endarterectomy
performed with less than 3% preoperative morbidity
and mortality is added to aggressive management
of modifiable risk factors . However, even when
magnetic resonance angiography (MRA) is performed
within 2 months after actual aberration occurs
it is difficult to detect such aberrations because
ultrasound or MRA studies are performed in the
supine rather than seated position .
We previously suggested that aberrations of the
carotid arteries in the head (ICA)  and neck (common
carotid artery, CCA) , which may occur when the
neck is bent forward, should be considered as new
risk factors for ischemic stroke. In addition, a casecontrol
study suggested that aberrant (Ab)-ICA
and Ab-CCA were risk factors for stroke and that
bent (head-down) posture was a risk factor for the
development of aberrant arteries .
Although patients with lacunar infarction were
excluded from the case group in our previous study,
we wanted to determine the actual cause of stroke.
Why were the aberrations related to ischemic stroke?
Were they due to plaque or cardiogenic embolism?
We therefore decided to analyze the results of
carotid artery ultrasound examination in the same
case and control groups, focusing in particular on the
atherosclerotic risk factor in stroke, to determine the
significance of arterial aberration and its relation to
We analyzed the original data from our previous
case-control study  using the chi-squared test and
paired t-test. This case-control study was performed
at the National Hospital Organization Tokyo Medical
Center after the Ethics Committee of each had
approved the study protocol. We compared the
presence or absence of Ab-ICA or Ab-CCA and of
plaque in the cervical carotid artery between 72
stroke patients and 163 individuals in the control
group. The total cholesterol, triglyceride, low-density
lipoprotein cholesterol, and high-density lipoprotein
cholesterol levels were also compared between the
two groups. The previous study specifically examined
the relationships among bent posture, height loss, aberration of the carotid arteries, and ischemic stroke
risk in a case-control manner. Both case and control
patients with established risk factors for stroke, such
as a history of atrial fibrillation, arrhythmia, heart
valve disease, diabetes, blood clotting abnormalities
(hematocrit >55%, platelet count >500,000/μl), and
who were receiving anticoagulant therapy were
excluded from the study . Furthermore, among the
235 patients, only 24 underwent complete routine
cervical ultrasound and had all cholesterol data
available. As a result, the current analysis involved
only a subset of 9 in the control group (without
ischemic stroke) and 15 stroke patients in the case
The characteristics of the case and control groups
are shown in (Table 1). There were no arterial
aberrations in the control group. On the other hand,
all ischemic stroke patients were found to have Ab-
ICA or Ab-CCA. Cervical ultrasound examination of
the carotid artery detected plaque in 5 of 9 in the
control group and in 11 of 15 in the case group. As
shown in (Figure 1), plaque prevalence was higher in
the stroke group than in the control group, although
the difference did not reach statistical significance
(odds ratio=0.45; 95% CI=0.06–3.1; Fisher’s
P-value=0.32; Table 2).
|Ischemic stroke cases
ICA/CCA: internal carotid artery/common carotid artery; TC: total cholesterol; TG: triglyceride; LDL: lowdensity lipoprotein; HDL: high-density lipoprotein
Table 1: Stroke occurrence, arterial aberration, plaque presence, and cholesterol values in the two groups in
the current subset analysis.
Figure 1: Plaque prevalence in both stroke and non-stroke groups.
||Odds ratio (95%CI)
CI: Confidence interval; INF: infinity
Table 2: Stroke patients and non-stroke controls with and without plaque and arterial aberration.
(Figure 2) shows the differences between total
cholesterol, triglyceride, low-density lipoprotein
cholesterol, and high-density lipoprotein cholesterol
levels between the case and control groups. The
t-test results indicated no significant differences in
cholesterol ratios between the two groups.
Figure 2: Differences of each cholesterol levels between the case and control groups.
Based on previous results, we estimated that
the risk of ischemic stroke was 90.2% based on
carotid artery aberration and 91.4% when all risk
factors (aberration of the carotid artery, height loss,
bent posture) were analyzed. Aberration of carotid
arteries caused by cervical bent posture was found
to predict ischemic stroke risk in the previous casecontrol
study . The purpose of that study was to
evaluate the accuracy of aberration of the carotid
artery as an ischemic stroke risk factor, and therefore
patients with established risk factors for stroke were
excluded. Thus the subset of patients analyzed in
this study was much smaller.
Although plaque was present in the CCA in about
one-half of the control group, none had experienced
a stroke. At the same time, two-thirds of the case
(stroke) patients had plaque in the CCA. This indicates that plaque tends to be a risk for stroke, although
the difference between the two groups was not
We previously treated patients in whom plaque
caused ischemic stroke when their carotid artery
became bent. Those patients reported an unusual
strange sensation (USS) when the aberration
occurred. The USS around the pharynx results from
a separation of the pharyngeal wall, which contains
the mucosa, submucosa, and superior pharyngeal
constrictor muscle, due to Ab-ICA. When that
separation occurs, patients feel a USS in the throat. The experience in treating those patients suggested
that the occurrence of the separation indicates an
increased risk of stroke in the near future and that
an ischemic embolism could be triggered .
The results of the present analysis indicate that:
1) the degree of atherosclerosis was the same in
both the case and control groups, because there
were no statistically significant differences between
them in cholesterol values; 2) the only difference
between the two groups was the aberration of the carotid artery; and 3) aberration of the carotid artery
tends to be a risk factor for stroke. The mechanism
of cerebral infarction is speculated to be artery-toartery
embolism from the carotid plaque. In other
words, plaque in the carotid arteries causes an
ischemic stroke when aberration of the carotid artery occurs, triggered by plaque reaching the cerebellum.
This research was supported by a Grant-in-Aid
for Clinical Research from the National Hospital
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