Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5776_Библиотеки_им_академика_М_И_Перельмана
.pdf
289Follow-up Neurosonologic Findings (5 Years)
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
Conventional Angiography (Day 5)
Digital subtraction angiography (DSA) was performed
to examine the presumed ICA stenosis and to rule out
vasculitis. Multiple irregular concentric constrictions
with normal and dilated intervening segments were
found in both distal extracranial ICAs, though predominantly aff ecting the right side. This “string of beads”
pattern led to the diagnosis of fi bromuscular dysplasia
(FMD) (Fig. B13.4 and Fig. B13.5). Mild caliber varia-
tions were also seen in the left distal vertebral artery
(VA) and the right renal artery. The intracranial vessels,
in particular the MCA branches, were not aff ected. Dis-
section and vasculitis were excluded.
Clinical Course (2)
A recurrent artery-to-artery embolism from the greater affected right ICA was assumed to be the most likely cause of
the stroke. Antiplatelet therapy was therefore commenced
for secondary stroke prevention. Interventional treatment
by stenting or surgery was not recommended because of
the complex vessel pathology and GPA. The GPA was treated with cyclophosphamide and corticosteroids. A clinical
follow-up 6 months after the initial presentation showed
only a minor improvement of the hemiparesis. ESR and
cANCA had normalized during the immunosuppressive
therapy. Cranial CT scan showed the residual large ischemic MCA territory infarction (Fig. B13.6). On this occasion
MRI was also performed which demonstrated Wallerian
degeneration of the pyramidal tract up to the pyramidal
decussation (Fig. B13.7). The patient remained asympto-
matic over the subsequent 5 years.
Follow-up Neurosonologic
Findings (5 Years)
Extracranial Duplex Sonography
B-mode sonography revealed unchanged mild atherosclerosis of the carotid arteries. In the right common carotid artery (CCA), a high-resistance fl ow signal was seen.
The right external carotid artery (ECA) showed an “internalized” low-resistance fl ow signal, indicating orbital col-
lateral fl ow. Doppler spectrum analysis of the proximal
right ICA demonstrated a “stump signal” (Fig. B13.8 and
Fig. B13.9).
Transcranial Duplex Sonography
The transcranial bone window had further worsened.
Doppler spectrum analysis of the right MCA revealed a
positive oscillation eff ect on slight digital tapping of the
left ICA at the submandibular level but not of the dominant VA at the atlas loop. The anterior communicating artery (ACoA) demonstrated turbulent fl ow. The remaining
intracranial vessels could not be visualized. The ophthalmic arteries (OAs) were not examined.
Fig. B13.1 Unenhanced CT, axial plane. Ischemic infarction in the right
anterior and posterior MCA territories (arrows). (Reproduced from
Braun et al. One stroke — two triggers. J Neurol 2006;253:1356–1357,
with permission of Springer.)
ICA-R
Fig. B13.2 Extracranial duplex, longitudinal plane. Slightly altered
fl ow signal in the right proximal ICA revealing a mildly reduced velocity and mildly increased pulsatility (fl ow velocity 47/24 cm/s).
290 Case 13 Right Internal Carotid Artery Stenosis in Fibromuscular Dysplasia and Granulomatosis with Polyangiitis
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
(formerly Wegener’s Granulomatosis)
Conclusion
Right ICA occlusion secondary to FMD. Suspected collateralization via the contralateral A1-ACA (cross-fl ow) and
ipsilateral OA.
ICA-R-distal
Fig. B13.3 Extracranial duplex, longitudinal plane. Color-mode
imaging demonstrates elongation, caliber variations, and stenosis (arrow) of the right distal ICA. Maximum peak systolic flow
velocity was 250 cm/s (not shown). Note the blue-colored internal jugular vein.
Final Diagnosis
Large territorial MCA infarction caused by artery-toartery embolism originating from the right ICA that was
severely aff ected by FMD. Thrombocytosis due to GPA
may have been a predisposing cofactor. Secondarily, clinically asymptomatic right extracranial ICA occlusion.
Fig. B13.4 DSA, right ICA injection, posteroanterior view: Multiple
irregular constrictions in a “string of beads” appearance in the right
distal ICA as a characteristic, pathognomonic angiographic fi nd-
ing of FMD. Note the severe stenosis within the mid part of the
e x t r a c r a n i a l I C A ( a r r o w h e a d ) . N o t e a l s o t h e e x t e n s i o n o f F M D i n t o
the proximal part of the petrous C6 segment of the ICA (arrow).
Fig. B13.5 DSA, left VA injection, lateral view. Mild caliber variations of the distal left-sided VA (arrowhead). Note the looping elongation of the distal VA segment (arrow).
Fig. B13.6 Unenhanced CT, axial plane. Large residual infarction of the right MCA territory 6 months after presentation. (Reproduced from Braun et al. One stroke – two triggers. J Neurol
2006;253:1356–1357, with permission of Springer.)
Fig. B13.7 MRI, T2-weighted image, coronal plane. Residual
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
right MCA infarction and Wallerian degeneration of the pyramidal tract down to the pyramidal decussation (arrows) 6 months
after presentation.
291Discussion
ICA-R
Fig. B13.8 Extracranial duplex, longitudinal plane. Occlusion of the
right ICA. A high-resistance fl ow signal with bidirectional fl ow com-
ponents (“to-and-fro signal”) can be detected in the carotid bulb.
Note the normal color imaging of the CCA and ECA.
ECA-R
Discussion
Clinical Aspects
Here we report on the rare coincidence of an infl amma-
tory condition (GPA) and a noninfl ammatory vessel dis-
ease (FMD). Both conditions have the potential to cause
ischemic stroke.
FMD is a nonatherosclerotic, noninfl ammatory seg-
mental vascular disease aff ecting intermediate-sized
arteries in many regions of the body. The fi rst case was
described in 1938 in a 5-year-old boy with severe uncontrolled hypertension (Leadbetter and Burkland 1938).
Possible etiologies such genetic factors, smoking, and estrogen have been discussed, but the cause of FMD is still
unknown (Olin et al 2014, Savard et al 2013, Slovut and
Olin 2004). A recent study reported an increased production of transforming growth factor β (TGF-β) in fi broblasts
and elevated TGF-β levels in plasma in patients diagnosed
with FMD, indicating a possible pathway for this disorder
(Ganesh et al 2014). Histopathologically, three distinct
types of FMD can be distinguished based on the arterial
layer aff ected: medial, intimal, or adventitial (Harrison
and McCormack 1971). The medial type of FMD is by far
the most common (70–90%) and is further subclassifi ed
into medial fi broplasia, perimedial fi broplasia, and medi-
al hyperplasia. Medial fi broplasia is characterized by al-
ternating segments of medial degeneration and collagen
deposition, which is classically diagnosed on angiography
after noting its “string of beads” appearance. This phenomenon is explained by the presence of luminal stenoses alternating with aneurysmal outpouchings. It may
be found over a length of 3–5 cm, mainly within the middle and distal parts of the aff ected vessels. Involvement
of proximal segments is hardly ever seen. FMD may also
occasionally aff ect intracranial arteries (Touzé et al 2010).
Fig. B13.9 Extracranial duplex, longitudinal plane. Right ECA
with a low-resistance fl ow signal indicating that the ECA is now a
brain-supplying artery (“internalized” fl ow signal).
Within the general vascular system, the renal arteries are
most frequently aff ected with an incidence of 85%, often
resulting in renovascular hypertension. The cervicocranial arteries are the second most common location, being
aff ected in 25–30% of cases. Of these, up to 95% involve
the ICA, 60–85% bilaterally (Healton 1986). About onethird of patients with ICA pathology also demonstrate
renal involvement. The VA is aff ected in up to 10% of cas-
es. Other vessels, for example, the intestinal arteries, may
also be involved (Slovut and Olin 2004).
Since 2008 the United States Registry for Fibromuscular Dysplasia has collected data on FMD patients, initially from 7, currently from 14 American centers. Based on
these data, more detailed demographic, clinical, and diagnostic information has been collected. Involvement of
the renal arteries was observed in 79.7% of 369 patients
and of carotids in 74.3% of 338 patients. Involvement of
the vertebral arteries was seen in 36.6%, mesenteric arteries in 26.3%, lower extremity arteries in 60%, intracranial ICAs in 17%, and upper extremity arteries in 15.9%
(Olin et al 2012). Furthermore, it was shown that renal
292 Case 13 Right Internal Carotid Artery Stenosis in Fibromuscular Dysplasia and Granulomatosis with Polyangiitis
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
(formerly Wegener’s Granulomatosis)
artery involvement is more common in men (89.7% versus 74.1% in women) and extracranial ICA involvement is
more frequently found in women (74.9% versus 44.1% in
men) (E.S. Kim et al 2013).
The peak age of FMD manifestation is around the fi fth
decade, with a clear female predominance. Hypertension
is the most common presenting symptom seen in 63.8%
of patients (Olin et al 2012, Stewart et al 1986). Depending on the aff ected vessel segments, grade of resulting
stenosis, and type of FMD, the clinical picture may range
from asymptomatic through mild to severe multisegmental vessel disease. In the mild variant, patients may
present with several unspecifi c symptoms such as head-
aches (52.4%), pulsatile tinnitus (27.5%), dizziness (26%),
neck pain (22.2%), and ocular symptoms including central artery occlusion. In severe disease high-grade arterial stenoses or thromboembolic events may occur which
subsequently result in transient ischemic attacks (TIAs)
or ischemic stroke (Choi et al 2014, Olin 1991, Touzé et
al 2010). Data from the U.S. FMD registry showed a high
incidence of hemispheric TIA (in 13.4% of patients), stroke
(in 9.8%), and amaurosis fugax (in 6%) (Olin et al 2012).
An association of intracranial aneurysms (Mettinger and
Ericson 1982) and ICA dissections (Desfontaines and
Despland 1995) has been reported. In the U.S. FMD registry evaluating 921 patients, dissections were detected in
25.7% of patients and aneurysms in 21.7%. The renal and
the extracranial carotid arteries were the most common
locations for aneurysms followed by an intracranial location. Contrarily, dissections were most common in the
extracranial carotid arteries followed by vertebral and
renal arteries. No intracranial dissection was reported
(Kadian-Dodov et al 2016). The true prevalence and incidence of the condition is diffi cult to assess as many pa-
tients demonstrate asymptomatic clinical courses. In the
U.S. FMD registry, 5.6% of FMD patients did not show any
clinical symptoms. In early reports of patients receiving
cerebral angiography for diff erent reasons, the reported
FMD prevalence varied between 0.3% and 3.2% (Corrin et
al 1981, Houser and Baker 1968, Mettinger and Ericson
1982, So et al 1981, Wesen and Elliott 1986). However,
this data cannot be extrapolated to the general population as the included patients were usually studied because of detected neurologic defi cits, in particular related
to cerebrovascular diseases.
In cases of accidental diagnosis, no specifi c treatment
is recommended. Treatment approaches are usually reserved for symptomatic patients. After the occurrence of
a fi rst ischemic stroke, patients are often commenced on
antiplatelet therapy. In recurrent ischemia or cases with
a hemodynamically relevant stenosis, endovascular or
surgical approaches might be required depending on the
appearance of the lesion. In recent years, endovascular
balloon dilatation or stent placement have been the favored approaches. Recent data from the U.S. FMD registry
reported 46.4% of patients receiving therapeutic procedures, including balloon angioplasty (52.9%) with stenting (20.4%) or arterial bypass surgery (11.1%). Hypertension, aneurysm, and dissection were the most frequent
indications. Treatment success rates in the registry were
reported to be 82.4% and complications occurred in 7.6%
of procedures (Gornik et al 2011). However, controlled
trials addressing this issue do not exist.
In our patient, mainly the ICAs were aff ected. The
right renal artery as well as the left VA were also involved
but were only mildly aff ected without clinically mani-
festations, especially no arterial hypertension. Vascular
intervention was therefore not advised, also bearing in
mind the immunologic comorbidity. During the 5-year
follow-up the patient developed an occlusion of the right
extracranial ICA which was clinically asymptomatic. It
is only retrospectively that we can question whether an
initial endovascular intervention might have prevented a
secondary occlusion. However, the clinically stable course
under medical therapy and the high periprocedural risk
of interventional treatment justifi es our chosen approach
in this case.
Our patient also suff ered from GPA (formerly known
as Wegener’s granulomatosis), a second rare disease.
GPA is an infl ammatory multisystem disease, one of the
antineutrophil cytoplasm antibodies (ANCA)-associated
small-vessel vasculitides (AAV). The disease is characterized by arteritis of small to medium-sized blood vessels,
and granulomatous infl ammation of the upper airways
and lungs (Seo and Stone 2004). Lung and renal involvement are common in patients with GPA, with necrotizing
glomerulonephritis. Other common features in GPA are
vasculitic skin lesions, peripheral neuropathy, mononeuritis multiplex, granulomatous meningeal involvement,
cardiac disease, and gut involvement (Hoff man et al
1992). The disease may occur at any age but the peak incidence is in the six and seventh decades of life. There is no
known gender diff erence. Laboratory analysis frequent-
ly demonstrates a raised ESR, raised C-reactive protein
(CRP), leukocytosis, thrombocytosis, and a mild normochromic anemia. A positive cANCA titer with proteinase 3
specifi city is found in 95% of patients with a systemic GPA
(de Groot and Gross 1998). GPA diagnosis is based on the
four American College of Rheumatology (ACR) criteria, of
which at least two have to be present: (1) oral or nasal
infl ammation, (2) abnormal chest radiograph, (3) micro-
hematuria, and (4) a positive biopsy showing granulomatous infl ammation within the wall or in the perivascular
space of an artery or arteriole. Neurologic manifestations
of GPA are reported in 22–54% of cases (Drachman 1963,
Nishino et al 1993). The peripheral nervous system is
most frequently aff ected. Neuropathies occur in ~16% of
cases and are associated with renal involvement. There
is cerebral or meningeal involvement in <10% of patients.
In these cases, intracranial or subarachnoid hemorrhages
in addition to arterial or venous occlusions might occur.
Generally these cerebrovascular events are caused by the
infl ammatory vasculitis. However, secondary arterial oc-
clusions due to direct invasion of the granulomatous infection originating from nasal or paranasal locations have
also been reported (Drachman 1963, Nishino et al 1993).
Generally, ischemic strokes are a rare complication of GPA
and are often the result of microangiopathic lesions based
on a coexisting hypertension (Nishino et al 1993).
Treatment of GPA usually comprises an approach with
cyclophosphamide or rituximab. In severe disease, a combined approach with cyclophosphamide or rituximab
293Discussion
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
plus plasma exchange is used. In refractory disease, treatment protocols involve administration of intravenous
immunoglobulins, infl iximab, alemtuzumab, and myco-
phenolate mofetil. For maintenance, drugs such as azathioprine or methotrexate, and mycophenolate mofetil or
lefl unomide are used (Tarzi and Pusey 2014).
In our case we assumed that FMD was the factor
responsible for the ischemic stroke. As the patient
presented 3 days after the onset of symptoms,
thrombo lysis was not possible. From the infarct pattern,
it was thought that the most likely cause was an arteryto- artery embolic event, from the predominantly aff ect-
ed ICA. Although a secondary thrombocytosis is not a
recognized independent risk factor for stroke, we consider the concomitant thrombocytosis caused by the
GPA to be a potential factor facilitating the formation of
a thrombus (Hart and Kanter 1990).
Angiologic and Anatomic Aspects
Diagnosis of FMD can be achieved by several methods.
Duplex ultrasound has a rather low sensitivity as the
vascular changes are often found in the middle and distal
ICA segments which are frequently not accessible by this
technique (Wells and Smith 1982). However, if the typical
“string of beads” pattern can be visualized, the diagnosis can also be made by ultrasound (see also Fig. A5.27).
In comparison to DSA, small vascular changes will often
escape the sonographic assessment (Arning and Grzyska
2004). If the disease causes arterial stenoses, additional
direct and indirect hemodynamic criteria can be determined by duplex ultrasound. In our case, we were able to
visualize a stenotic and elongated vessel course as well as
caliber changes within the middle ICA segment.
If comprehensive morphologic as well as functional neurovascular assessment is the goal, MRI including
DWI, arterial spin labeling (ASL) perfusion and ce-3D
(or 4D) MRA would be the appropriate choice. The ASL
technique allows searching for critical perfusion defi cits
without the need of intravenous contrast application.
Ce-MRA can be done immediately afterward to search
for typical morphologic FMD signs, i.e., “string of beads”
appearance. Ce-3D-MRA is a highly accurate technique
for cervical vessel assessment (Chandra et al 2012). If
vessel assessment alone is intended, multislice CTA, especially using the dual-source technique, is suitable as it
noninvasively combines high spatial resolution and artifact reduction. For renal artery FMD, sensitivity comparable to DSA has been reported (Sabharwal et al 2007).
For brain-supplying arteries, to date there have been
only singular reports in regard to FMD (de Monyé et al
2007). Recently, the use of multicompartment CTA has
been proposed in patients with spontaneous coronary
artery dissection (Liang et al 2014). There, CTA was able
to show extracoronary vessel abnormalities in 69% of
cases, the majority of which (31%) in fact involved cervical vessels including FMD.
Finally, important hemodynamic aspects of our
present case should be discussed. On the day of admission, our patient demonstrated diff erent fl ow velocities
in both M1-MCA segments (right, 57/25 cm/s; left,
111/57 cm/s). As the proximal MCA segments often follow a similar course, fl ow velocity diff erences between
the two sides should be small. The clearly reduced velocity in our patient’s right MCA was therefore suggestive of a distal M1 occlusion or an occlusion of a dominant M2-MCA branch. Depending on the location of an
MCA occlusion, diff erent eff ects can be observed in the
proximal vessel segments (for further details, see Chapter 5, “MCA Occlusion” under “Intracranial Pathology”).
For instance in proximal M1-MCA occlusion, fl ow will
be absent. A more distal M1-MCA occlusion beyond the
lenticulostriate branches will result in a more or less reduced fl ow velocity and increased pulsatility within the
proximal M1-MCA segment depending on the presence
and diameter of an early temporal branch (for further
details see Case 22). In M2 branch occlusion, proximal
M1-MCA fl ow may vary depending on the relevance and
number of M2-MCA branches. In case of a major M2
branch occlusion, proximal M1-MCA fl ow will be re-
duced but less than in distal M1-MCA occlusion. In case
of a small M2 branch involvement, fl ow in the proximal
M1-MCA can be normal (see also Fig. A5.98). Based on
initial transcranial Doppler (TCD) experiences in acute
stroke, Zanette and coworkers developed an index permitting conclusions regarding MCA patency and the site
of a MCA occlusion (Zanette et al 1989). This “asymmetry index” (AI) is calculated as follows:
AI (%) = (V
− Va) / (Vn + Va) × 200
n
where AI is the asymmetry index, Vn is the mean fl ow ve-
locity of the normal MCA, and V
of the aff ected MCA.
is the mean fl ow velocity
a
Using transcranial Doppler (TCD), the AI can be applied
if velocities are assessed at similar insonation depths. A
complete occlusion results in the maximal achievable
index of 200%. Side-to-side diff erences >21% are consid-
ered pathologic. High values argue in favor of a distal M1
occlusion and low values are suggestive of an M2-MCA
occlusion. Although developed for TCD, the index can
nevertheless be transferred to transcranial color-coded
sonography (TCCS). As TCCS makes it possible to perform
angle-corrected velocity measurements, the index might
yield an even higher accuracy than published; however,
this hypothesis has not been verifi ed (Kenton et al 1997).
In clinical practice the use of systolic fl ow velocities for AI
calculation can be recommended, as they are easier to assess, particularly in acute stroke patients. A simplifi ed ap-
proach is to use a 30% bilateral diff erence as a pathologic
cut-off . Again, this is only true if comparable vessel seg-
ments are being used for evaluation. The AI has been used
to establish the Thrombolysis In Brain Ischemia (TIBI) criteria at TIBI grade 2 and 3 with a blunted or dampened
fl ow signal and mildly raised pulsatility. The advantage of
a simple right-to-left comparison is its rapid assessment
even under acute stroke conditions. Saqqur and coworkers found a sensitivity of 94%, a specifi city of 100%, and
positive and negative predictive values of 100%, and 86%,
294 Case 13 Right Internal Carotid Artery Stenosis in Fibromuscular Dysplasia and Granulomatosis with Polyangiitis
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
(formerly Wegener’s Granulomatosis)
respectively for identifying proximal occlusion in the anterior circulation, if the V
2005b). In our case, considering the systolic fl ow veloci-
ratio was <0.6 (Saqqur et al
a/Vn
ties, the AI was 64%, the diff erence between the two sides
was 51%, and the right-to-left ratio was 0.51. Therefore,
a distal M1-MCA occlusion or an occlusion of more than
one M2-MCA branch had to be assumed. The follow-up
CT demonstrated a large MCA infarction excluding the
basal ganglia, supporting a distal M1-MCA occlusion
as the cause of stroke. DSA 5 days later did not show a
persisting vessel occlusion, indicating spontaneous
recanalization.
Case 14
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
Isolated Left Carotid Siphon Stenosis
295
Clinical Presentation
A 17-year-old Caucasian woman presented with recurrent transient episodes of right-sided sensorimotor defi cits and speech disturbance, each lasting up to
60 minutes. The symptoms had fi rst occurred 3 years
before presentation with a transient numbness of the
fi ngers of her right hand. One week before admission to
a district general hospital, she developed brachiofacial
hemiparesis and Broca-type aphasia. These symptoms
gradually resolved after 15 minutes. She had no vascular risk factors and no history of migraine or stroke in
her family. She had never used illicit drugs. Clinical examination yielded no focal neurologic defi cit. She was
started on a combination of aspirin and clopidogrel and
was then referred to our department for further evaluation following MR angiography (MRA) and digital
subtraction angiography (DSA), which showed contradictory fi ndings.
Initial Neuroradiologic Findings
Cerebral MRI revealed no ischemic parenchymal lesions.
Time-of-fl ight (TOF)-MRA demonstrated a severe left
carotid siphon stenosis. Also a fetal-type left posterior
cerebral artery (FT-PCA) was noted (Fig. B14.1 and Fig.
B14.2). In contrast to the MRA fi ndings, conventional DSA
1 day later demonstrated only a mild stenosis in the left
distal carotid siphon despite the use of diff erent oblique
p r o j e c t i o n s ( Fig. B14.3, Fig. B14.4, Fig. B14.5, Fig. B14.6,
Fig. B14.7).
Initial Neurosonologic Findings
Extracranial Duplex Sonography
B-mode and color-mode imaging revealed no atherosclerosis or other vascular pathology. Doppler spectrum anal-
Transcranial Duplex Sonography
Increased fl ow velocities with turbulence were found
in the left proximal M1-MCA segment using the midbrain plane (fl ow velocity 141/61 cm/s). No poststen-
otic fl ow pattern was detected in the distal M1-MCA
segment and M2-MCA branches. Tilting the probe to
the upper pontine plane, the carotid siphon presented fl ow velocities reaching peak systolic values of
300 cm/s. Both anterior cerebral arteries (ACAs) and
PCAs, and the right MCA, showed normal fl ow signals.
A positive oscillation eff ect was observed in the left P2-
PCA segment upon ipsilateral extracranial internal carotid artery (ICA) artery tapping (Fig. B14.8, Fig. B14.9,
Fig. B14.10; see also Video
B14.1).
Conclusion
High-grade but not hemodynamically relevant stenosis of
the left carotid siphon with turbulent fl ow in the proxi-
mal M1-MCA segment. Left fetal-type PCA.
Clinical Course
Suspected Diagnosis
Recurrent transient ischemic attacks (TIAs) in the territory of the left middle cerebral artery (MCA) caused by a
carotid siphon stenosis of undetermined origin and unknown degree.
Questions to Answer by
Ultrasound Techniques
• Were there pathologic vascular changes in the extra cranial vessels?
• What was the conformation and grading of the stenosis
in the left carotid siphon?
• Was there evidence of any further intracranial stenotic
process, overrated by MRA or underrated by DSA?
The patient’s recurrent TIAs were interpreted as embolic
events in the left MCA territory, caused by the high-grade
carotid siphon stenosis. The etiology of the stenosis remained unclear. Blood pressure measurements were
normal. Other causes, such as vasculitis or chronic infl ammatory disease, were considered unlikely because of
the clinical presentation, normal blood tests, and normal
c e r e b r o s p i n a l fl uid (CSF) studies. Diff erential diagnoses
such as early moyamoya syndrome or fi bromuscular dys-
plasia (FMD) could not be confi rmed at the stage of disease
at which she presented. We changed the secondary stroke
prevention to monotherapy with clopidogrel and recommended follow-up ultrasound examination after 1 year.
Unfortunately, the patient was lost to follow-up.
296 Case 14 Isolated Left Carotid Siphon Stenosis
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
Fig. B14.1 Intracranial 3D TOF-MRA, left anterior oblique projection. High-grade carotid siphon stenosis of the left ICA at the C2–
C3 junction (arrowhead).
Fig. B14.3 DSA, left ICA injection, posteroanterior view. No visible
stenosis in the left carotid siphon.
Fig. B14.2 Intracranial 3D TOF-MRA, right anterior oblique projection. Comparable high-grade carotid siphon stenosis of the left
ICA (arrowhead).
Fig. B14.4 DSA, left ICA injection, lateral view. DSA only demonstrates
a low-grade stenosis in the left carotid siphon distal of the ophthalmic
artery origin (arrowhead). Note the fetal-type PCA (arrow).
Fig. B14.5 DSA, left ICA injection, left anterior oblique view. The
carotid siphon stenosis is not visualized.
Fig. B14.6 DSA, left ICA injection, right anterior oblique view. On
this projection, again a low-grade stenosis in the left carotid siphon
distal of the ophthalmic artery origin was assumed (arrowhead).
ICA-Siph-L
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
297Discussion
Fig. B14.7 MRA (left) and DSA (right). Comparative views by
both methods using a similar plane and magnifi cation suggesting
a high-grade siphon stenosis on MRA (left) and normal fi ndings
on DSA (right).
M1-MCA-L
Fig. B14.9 TCCS (tran stemporal appro ach) , left -sid ed ins onati on,
midbrain plane. Mildly raised fl ow velocities and slight turbulences
in the left proximal M1-MCA in a depth of 58 mm (fl ow velocity
141/61 cm/s).
Final Diagnosis
Repeated TIA in the left MCA territory caused by a highgrade carotid siphon stenosis of unknown etiology, clearly underrated by conventional DSA.
Discussion
Clinical Aspects
Here we present a very young patient who was transferred to our hospital because of recurrent left-hemispheric TIAs caused by a high-grade left carotid siphon
stenosis. It remained unclear whether the events were
of embolic or hemodynamic origin. The benign course of
the recurring events without development of a manifest
Fig. B14.8 TCC S (trans temporal a ppro ach), left -sided i nson ation, upper pontine plane. Doppler spectrum analysis showed
increased fl ow velocities in the left carotid siphon (fl ow velocity
300/150 cm/s).
M1-MCA-L
Fig. B14.10 TCC S (t rans tempo ral ap proa ch), l eft- sided insonation, midbrain plane. Normal Doppler signal and fl ow velocity in
the left midpart of M1-MCA at a depth of 50 mm (fl ow velocity
111/42 cm/s).
ischemic stroke could argue in favor of hemodynamic
events. However, the virtually normal MCA fl ow profi les,
the absence of an orthostatic component, normal blood
pressure levels, and the termination of recurrent symptoms after starting the antiplatelet medication argues in
favor of the embolic event hypothesis.
Her fi rst clinical manifestation occurred at the age of 14,
which prompted an extended investigation. No classic vascular risk factors were found. A cardiac embolic source was
ruled out and investigations excluded vasculitis, chronic infl ammatory disease, and thrombophilia. Early-stage
moyamoya disease or FMD seemed possible but could
not be confi rmed at that stage (for further discussion on
moyamoya disease, see also Case 9, and for discussion on
FMD, see Case 13). Another diff erential diagnosis in this
young patient was dissection, an isolated vasospasm, or an
idiopathic reversible cerebral vasoconstriction syndrome.
298 Case 14 Isolated Left Carotid Siphon Stenosis
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
However, the absence of a head trauma or migraine, lack of
clinical symptoms such as headaches or eye pain, and DSA
fi ndings that were not typical for vasospasm or dissection
argue against these suggestions. Furthermore, the stenosis
remained unchanged over an observational period of more
than 1 week (time delay between MRA and transcranial
color-coded sonography [TCCS]), which argues against a
vasospasm. The isolated involvement of one vessel segment also was not typical for a reversible cerebral vasoconstriction. As there was no past medical history concerning
the use of illicit drugs or antidepressants, Call–Fleming
syndrome as variant of a reversible segmental cerebral
vasoconstriction caused by vasoactive sympathomimetic
drugs also seemed unlikely (Call et al 1988, Noskin et al
2006). For further reading on reversible cerebral vasoconstriction syndrome see Case 36). Unfortunately, the patient
was lost to follow-up and the question of a persisting or
transient stenosis could not fi nally be answered. An ather-
osclerotic lesion seemed unlikely because of the lack of risk
profi le, negative family history, and the patient’s young
age. Therefore, the exact etiology of the detected carotid
siphon stenosis remains unclear, but an isolated atypical
dissection was our favored assumption.
In typical cases with intracranial atherosclerotic pro-
cesses the ICA and, in particular, the carotid siphon is frequently aff ected. Akins and coworkers (1998) performed
angiographic follow-up studies in 21 patients with 45
intracranial arterial stenoses; 49% of lesions aff ected the
intracranial ICA with a stenosis >50%. Compared with
stenoses in the ACA, MCA, and PCA, the ICA stenoses remained relatively stable without any relevant progression
over an observation period of 26.7 months. The authors
assumed that a mild progression in smaller-caliber vessels such as the ACA, MCA, and PCA resulted in a relatively
greater narrowing compared to a large vessel as the ICA.
Another interesting observation was that the absence of
extracranial atherosclerosis seemed to be a risk factor for
intracranial stenosis progression. The authors observed
not only progression but also regression of stenoses, the
latter being attributed to a presumed partial recanalization of intravascular thrombi (Akins et al 1998). The
distribution of intracranial stenosis varies according to
the diagnostic method and the population studied. In
i n t r a c r a n i a l a t h e r o s c l e r o t i c p r o c e s s e s , r e c e n t s t u d i e s r e port an involvement of the ICA in 10–28% (Homburg et
al 2011, Ovesen et al 2013, Mazighi et al 2008, J.T. Kim et
al 2006, and Mazighi et al 2006). A detailed discussion of
distribution in intracranial atherosclerosis can be found
in Chapter 5, “Stenoses” under “Intracranial Pathology.”
The true incidence of an isolated stenosis of the carotid siphon is not known. In a larger angiographic study
including 885 consecutive angiograms a unilateral (71
patients) or bilateral (22 patients) isolated carotid siphon
stenosis of atherosclerotic origin was present in 10.3% of
cases (Borozan et al 1984). However, in another study, a
concomitant stenosis of the ipsilateral proximal ICA was
present in 14 of 15 cases (Wechsler et al 1986). A detailed
discussion of treatment options in intracranial stenoses
can be found in Case 5.
Angiologic and Anatomic Aspects
As intracranial stenotic processes are frequently found in
the ICA, and in particular within the carotid siphon, valid
diagnostic tools are required for exact evaluation of these
vessel segments. For routine ultrasound examination
in patients with TIA or stroke in the MCA territory and
normal extracranial fi ndings, it is essential to extend the
examination to the complete intracranial ICA as well as
the accessible MCA, i.e., the M1-, M2-, and even M3-MCA
segments. The intracranial ICA can be insonated via the
transtemporal bone window using transcranial Doppler
(TCD) or TCCS (Bogdahn et al 1990, Ley-Pozo and Ringelstein 1990). Because of the restricted spatial orientation
and vertically orientated course of the intracranial ICA,
the use of TCD is of limited value. If TCCS is used and a
patent transtemporal bone window is present, the total
intracranial ICA including the proximal (petrosal) C6, the
C5 segment, the carotid siphon (C3- and C4-ICA), and the
C1 and C2 segments can be assessed using combined axial and coronal insonation planes (Eggers et al 2009, Jurgita et al 2002). If a transtemporal bone window is absent,
the transorbital approach using TCD or TCCS at least for
the carotid siphon can be considered if restrictions concerning the insonation energy are being observed (Hu et
al 1995, Ley-Pozo and Ringelstein 1990, Lindegaard et al
1986, Schneider et al 1991, Spencer and Whisler 1986).
Because of its often tortuous intracranial course,
angle-corrected measurements of the carotid siphon
are usually not recommended. Also, a turbulent fl ow
pattern is frequent, due to loops, and thus may not be
indicative of vessel stenosis. Whenever an obviously turbulent fl ow pattern and raised fl ow velocities are seen
together, however, a stenosis should be suspected. Our
example also illustrates the importance of a complete
intracranial ultrasound assessment. The proximal M1MCA segment demonstrated mildly raised fl ow veloc-
ities (141/61 cm/s) and a turbulent fl ow which alone
could have been interpreted as a low-grade MCA stenosis. However, in our case this profi le alteration corre-
sponded to the transmitted stenotic signal from the carotid siphon stenosis. Therefore, in any case of suspected
MCA stenosis, the pre- and poststenotic vessel segments
(i.e., M2-MCA, C1/C2-ICA, and carotid siphon) have to be
examined to avoid misinterpretation of fi ndings and, as
in our example, to diff erentiate between isolated proxi-
mal MCA and distal ICA stenoses.
Because of its close anatomic proximity to the base
of the skull and its tortuous course, examination of the
carotid siphon using other angiologic methods is also
diffi cult. Standard multislice CTA clearly shows and dis-
tinguishes soft and hard plaques within any given ICA
segment, but postprocessing techniques, i.e., the widely
used maximum intensity projection, are restricted by the
proximity of vessel and bone at the skull base (Woodcock
et al 1999). Therefore, diff erent bone subtraction tech-
niques have been developed including manual segmentation, matched mask bone elimination, and dual-source
CTA (Cheng et al 2015, Romijn et al 2008). Most studies
Соседние файлы в папке Библиотека им академика М.И. Перельмана