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Case 28 Subclavian Steal Phenomenon in Subclavian Artery and Internal Carotid Artery Occlusion
326
Degree of Neurosonologic Difficulty: High
Fig. B28.26 DSA, brachiocephalic angiogram, left anterior oblique
(LAO) view. Proximal occlusion of the right SA (arrow).
Fig. B28.28 Schematic drawing of the extra- and intracranial brainsupplying arteries of the patient in Case 28. Right proximal ICA
occlusion and left proximal SA occlusion (circles). Collateralization
of the right MCA territory through the right VA via BA and right
PCoA. Collateralization of the right ACA territory in part through the
left ACA. Bloodsupply to the left distal SA via retrograde left VA from
the right VA (arrows). Note, that the right VAprovides the blood flow
for the total posterior circulation, right MCA territory, part of the
right ACA territory and left arm.
Fig. B28.27 DSA, right VA injection, lateral view, late arterial phase.
Note the retrograde left VA filling (arrows) and the distal SA filling
(arrowhead) following contralateral VA contrast injection.
Discussion
Clinical Aspects
Our 50-year-old patient had severe atherosclerosis of the
brain-supplying arteries associated with multiple vascular
risk factors including nicotine misuse. The clinical picture
was dominated by a right MCA infarction, triggered by a
right ICA occlusion. An asymptomatic left subclavian steal
phenomenon (SSP) on the basis of a left proximal SA
occlusion was also detected. Both pathologies resulted in
a complex extra- and intracranial hemodynamic situation.
Because of the good regression of neurologic deficits, the
patient’s young age, and the exhausted CVR, an STeA-MCA
bypass operation was performed to improve the perfusion
of the right hemisphere. In the following discussion we
will first address the implications of ICA occlusion and
secondly those of the SSP.
The incidence of symptomatic unilateral ICA occlusions
is 6/100 000 (Flaherty et al. 2004). Considering that not
every patient suffering a transient ischemic attack (TIA)
consults a doctor, these numbers may even be higher. The
incidence of asymptomatic ICA occlusions is unknown.
Cerebral or retinal ischemia on a background of an ICA
occlusion may be embolic or hemodynamic in nature. In
most cases an embolic event occurs, which, due to the
anatomic vessel course, will often result in MCA territory
ischemia.Ithasbeenassumedthatapproximately15%of
large embolic artery infarctions are caused by acute ICA
occlusions. The underlying mechanism of periocclusive
embolism might be a critical slowing of blood flow within
a stenosis. This then leads to embolus formation which in
the moment of ICA occlusion detaches, and leads to intra-
Discussion
327
cranial vessel occlusion and infarction. Embolism may,
however, also occur after completed vessel occlusion
from the distal “tail” of a propagating carotid thrombus
(Finklestein et al. 1980). Only rarely will the proximal
stumpoftheoccludedICAbethesourceofemboli,for
example, if the occlusion is located more distally and an
embolus originating from the stump follows the collateral
pathways via the ECA and retrograde OA into the brain. In
such a case, atherosclerotic vessel wall changes within the
CCA and ECA might also result in artery-to-artery cerebral
embolic events (Barnett et al. 1978).
Hemodynamic compromise is the second common
cause of ischemia in ICA occlusions (Pessin 1979). In cases
with insufficient collateral blood supply, reduced perfusion in the border zones between the vascular territories
may result in hemodynamic infarctions. This assumption
is supported by an obvious association of border zone
infarctions and ICA occlusions or high-grade stenoses
(Baumgartner and Regard 1994, Hupperts et al. 1996, Weiller et al. 1991) (for further discussion on border zone
infarction, see also Chapter 5, “Collateral Pathways,”
p.101, and Case 30, p. 338). Hemodynamic TIAs may
present with specific patterns. Often, TIAs occur with cortical signs, for example, in relation to orthostasis (Caplan
and Sergay 1976, Ruff et al.1981, Sommerville 1984). Occasionally “limb shaking” may be observed. This phenomenon, first described in 1962 by Fischer, comprises unilateral repetitive involuntary movements of arm and/or legs
without epileptic activity on electroencephalogram (EEG)
analysis. The detailed mechanism of this phenomenon is
not well understood, however, it ceases after successful
carotid endarterectomy (CEA) or an EC–IC bypass (Baquis
et al. 1985, Tatemichi et al. 1990, Yanagihara et al. 1985). In
contrast to amaurosis fugax, usually associated with extracranial ICA stenoses and indicative of artery-to-artery
embolism, a transient retinal ischemia or “retinal claudication” is a less known symptom. Looking into bright light
increases the retinal metabolic demand. In combination
with the already impaired retinal perfusion in patients
with an ICA occlusion this may subsequently manifest by
diminished visual acuity after visual stimuli (Furlan et al.
1979). Chronically reduced orbital blood flow may lead to
venous stasis retinopathy, which is often clinically asymptomatic and may be diagnosed by ophthalmoscopy. In
patients with ICA occlusion a venous stasis retinopathy
was observed in 32 of 110 patients (29 %). Clinically manifest chronic ocular ischemia is rare with a published annual rate of 1.5% (Klijn et al. 2002).
Both ischemic mechanisms, embolic and hemodynamic,
may potentiate each other. Animal experiments have demonstrated that the extent of embolic infarctions rises in
cases with generally impaired cerebral hemodynamics,
probably as a result of insufficient and delayed disruption
of emboli (Omae et al. 2000)
The functioning of the available collaterals determining
the degree of impairment in cerebral hemodynamics can
be assessed by several diagnostic methods, such as PET,
SPECT, MRI, and transcranial ultrasound. A measure of
collateral function is the CVR which can easily be determined by transcranial Doppler (TCD) (see also Chapter 3,
“Metabolic Coupling,” p. 57). Applying this method to patients with an ICA occlusion, approximately 12 % of cases
demonstrate an exhausted and 29 % an impaired CVR
(Widder et al. 1994). The former was especially seen in
patients who had experienced cerebral ischemia in the 3
months prior to the analysis. In cases with acute occlusion,
the CVR undergoes constant changes as collateral function
may improve over time. Therefore, CVR improves over
time too and may not be stable before 3–4weekspost
ischemia. The assumption that CVR normalization occurs
over several months,however, was not confirmed (Rutgers
et al. 2000). In our patient, we repeated CVR testing after 4
weeks, which demonstrated further progression of the
hemodynamic failure.
Patients with asymptomatic ICA occlusions have a good
long-term prognosis. A case series in 30 patients reported
only one ischemic stroke during an observational period of
32 months (Powers et al. 2000). An analysis of symptomatic patients from 20 clinical studies, who had suffered a
retinal TIA, cerebral TIA, or minor stroke, revealed a general annual risk of stroke of 5.5 % and a risk of an ipsilateral
stroke of 2.1 %. Patients with impaired CVR had an even
higher annual risk of 12.5 % for general stroke and of 9.5 %
for ipsilateral stroke, both substantially higher than for the
total group of ICA occlusions. Patients with an exhausted
CVR had the highest risk with 41.4 % for general stroke and
31% for ipsilateral stroke, respectively (Klijn et al. 1997).
Secondary stroke prevention is mainly achieved by
medical approaches. Independent from the cause of
stroke, the overall annual risk of stroke recurrence, myocardial infarction, or vascular death ranges between 4 %
and 16 %. Aspirin reduces the relative risk by approximately 13% (Algra and van Gijn 1996). Based on these
data, first line medical treatment for secondary stroke
prevention in ICA occlusions is aspirin. However, it is unclear whether patients with compromised hemodynamics
benefit equally frominhibition of thrombocyte function. In
cases of acute ICA occlusion, anticoagulation therapy for a
number of weeks might be considered to prevent embolic
events from the stump. However, there are no controlled
trial data to support this approach.
Another therapeutic aspect is blood pressure management. Large epidemiologic studies have shown that blood
pressure reduction leads to subsequent reduction of stroke
risk. However,in patients with impaired hemodynamics or
in cases with bilateral high-grade ICA stenoses (> 70 %
NASCET criteria, > 82 % ECST criteria) normal blood pressure might be a risk factor for recurrent cerebral ischemia.
In these cases, moderately elevated blood pressure values
might be tolerated or an intervention (such as CEA or
stenting of an ipsilateral asymptomatic high-grade stenosis in case of contralateral ICA occlusion) considered. In
cases of unilateral chronic ICA occlusion, a deliberate increase of blood pressure is not recommended as it does not
Degree of Neurosonologic Difficulty: High
Case 28 Subclavian Steal Phenomenon in Subclavian Artery and Internal Carotid Artery Occlusion
328
reduce the risk of future strokes but increases the risk of
cardiac events (Rothwell et al. 2003c).
Interventional revascularization approaches such as the
insertion of an EC–IC bypass are controversially discussed
but have been largely abandoned after publication of the
EC-ICBypassStudyresultsin1985.Inthistrial,which
included patients with symptomatic high-grade ICA or
MCA stenosis or occlusion, no benefit was found for patients who had been operated on compared with those
who had best medical treatment (EC–IC Bypass Study
Group 1985) (see also Case 25, p. 297)
Besides the ICA occlusion our patient presented an occlu-
Degree of Neurosonologic Difficulty: High
sion of the left proximal SA and a subsequent subclavian
steal phenomenon. A subclavian steal phenomenon is defined as the reversal of blood flow in a VA, ipsilateral to an
upstream proximal high-grade SA stenosis or occlusion.
The VA then takes over the insufficient blood supply of the
ipsilateral arm. Fisher named the phenomenon “subcla-
vian steal” in 1961 as the ischemic arm “steals” blood from
the intracranial circulation. The reported prevalence of the
subclavian steal phenomenon is between 1.9 % (in a population-based analysis of blood pressure differences
> 15 %) and 9 % (in patients with a neck bruit) (Bornstein
and Norris 1986, English et al. 2001, Hennerici et al. 1988,
Lord et al. 1969, Shadman et al. 2004). Atherosclerotic
occlusive disorders of the SA correlate with past and current smoking history, hypertension, and especially with
the presence of a peripheral arterial occlusive disease
(PAOD). An angiographic study by English and coworkers
(2001) reported a prevalence for SA stenosis of 4.3 % in
patients with nicotine misuse, 6.8 % in patients with diabetesmellitus,7.6%inpatientswithcerebrovascular
events, and 11.5 % in patients with PAOD). In the majority
of cases the underlying pathology for SA stenosis is atherosclerosis. However, other causes such as congenital
deformities, traumatic injuries, emboli or inflammatory
diseases, in particular Takayasu arteritis, might lead to
thesubclavianstealphenomenon(seealsoCase23,
p. 279).Depending on the anatomic vessel course, SA stenoses or occlusions with subsequent subclavian steal occur
in two-thirds of cases on the left and in one-third of cases
on the right side (Kaneko et al. 1998, Tan et al. 2006).
Whenever transient or persisting clinical symptoms are
observed, the term subclavian steal syndrome is used instead of subclavian steal phenomenon. A variety of symptoms may occurincluding headaches, episodesof transient
brainstem ischemia, activity-related pain, sensible irritations as well as impaired strength in the affected arm.
Headaches, particularly located in the neck, or the mastoid
or occipital regions, which may be amplified by physical
activity, are frequently reported in subclavian steal syndrome. Resting and exertional arm pain or other impairments ofthe arm arerather infrequent findings. This might
be explained by the slow progression of the SA occlusive
disorder with the subsequent development of other additional collateral pathways. TIAs are often short, lasting
seconds to minutes only. The symptoms may be difficult
to recognize as they often only become obvious if there are
additional occlusions in the anterior circulation or there is
inadequate collateralization. A large study including 324
patientswith a subclavian steal phenomenonfound symptoms related to an impaired perfusion of the posterior
circulation in 5 % of cases only. In contrast, 31 % had, as in
our case, symptoms attributable to the anterior circulation
because of a generalized severe atherosclerosis also affecting the carotid arteries. The remaining 64 % of patients
were asymptomatic (Hennerici et al. 1988).
When consideringtherapeutic measures, the oftencomplex vascular constellation has to be taken into consideration. Until the 1980 s, patients with a subclavian steal
were often treated by vascular surgery even if they were
asymptomatic. Today these procedures are only considered in symptomatic patients and after critical evaluation
of the complete hemodynamic situation. In most cases,
however, no intervention is required (for further discussion on therapeutical aspects, see also Case 23, p. 279).
Angiologic and Anatomic Aspects
The subclavian steal phenomenon is characterized by a
reversal of flow within the affected VA, illustrating the
compensatory ability of the cerebral circulation. Determined by the degree of the SA stenosis, three grades of
the subclavian steal phenomenon can be differentiated
(Thomassen and Aarli 1994):
• Grade 1—incipient subclavian steal phenomenon: This
grade is characterized by a gradual diminution of sys-
tolic VA flow but preserved diastolic flow, called systolic
deceleration. This depression in flow velocity reflects a
loss of VA perfusion pressure during the highest flow
velocity in the SA (Kliewer et al. 2000).
• Grade 2—incomplete subclavian steal phenomenon:
This grade is characterized by a pressure adjustment
leading to a biphasic alternating flow signal with a ret-
rograde systolic and an orthograde diastolic flow com-
ponent.
• Grade 3—complete subclavian steal phenomenon: This
is characterized by a complete flow reversal, observable
in all segments of the affected VA, which usually occurs
in complete SA occlusion.
ThesamemonophasicVAflowprofilecanthenalsobe
observed in the dependent distalarteries, e.g., the brachial
artery which allows a fast indirect evaluation of SA pathology. The described flow patterns apply to the patient at
rest. Muscular activity within the affected arm leading to
reactive hyperperfusion will alter the observed VA flow
profiles. This principle may also be applied as a controlled
test for the subclavian steal phenomenon. A blood pressure cuff, positioned on the affected arm is inflated above
systolic blood pressure levels under continuous monitoring of the VA flow. During this phase of arm ischemia the
VA flow may improve or normalize. On sudden release of
Discussion
329
thepressurecuffthearmbecomeshyperemicandtheVA
flow abnormality worsens, usually by one grade. Such a
change was observed in our patient. The description of
findings in the ultrasound report should therefore include
the subclavian steal phenomenon grade at rest and under
provocation unless grade 3 subclavian steal phenomenon
is already present at rest.
Ultrasound diagnosis of the subclavian steal phenomenon is easy as the combination of extracranial duplex and
TCCS permits a clear description of flow pathology within
the extra- and intracranial VAs and the BA. In patients with
a grade 2 or 3 subclavian steal phenomenon the diagnosis
is straightforward. More difficult may be the differentiation of grade 1 subclavian steal phenomenon from a mildly
poststenotic flow, caused by a proximal VA stenosis, which
might not be accessible to ultrasound diagnostics. In these
casestheabovebloodpressurecufftestwillbeofhelpas
no relevantmodulation of the flow profile is tobe expected
inthecaseofproximalVAstenosis.
Another hemodynamic effect of subclavian steal phenomenon onto the posterior circulation is the increased
flow in the nonaffected VA, which occurs in all cases with a
vertebrovertebral overflow. As to be expected, this effect
will be greater in grade 3 than in grade 2 subclavian steal
phenomenon (Tan et al. 2006). Furthermore, the subclavian steal phenomenon may additionally provoke a basilar
steal phenomenon. An incomplete basilar stealcomprising
a systolic flow deceleration at rest was seen in seven of 55
patients with subclavian steal phenomenon, increasing to
25 if additional provocation tests were performed. A complete basilar steal phenomenon, however,is a rare finding.
It was found at rest only in one patient in this study. A
basilar steal was present in seven of eight cases with
definitive symptoms of posterior circulation and in five
of six symptomatic patients with a > 50 % contralateral VA
stenosis, indicating that patients with a basilar steal are at
higher risk of stroke (de Bray et al. 1994).
Our case presented a pathologic poststenotic flow pattern, not only in the BA but also in both PCAs without the
presenceofaproximalVAorBAstenosis.Thisflowalteration can therefore be explained by the proximal SA occlusion and by a lack in collateral blood flow from the
anterior circulation due to an additional extracranial ICA
occlusion. At least the nonaffected right VA assured the
blood supply of the left arm, the brainstem, both PCA
territories, the right MCA territory and in part the right
ACA territory which explains the high flow velocity detected in the right V2-VA segment of 160/88 cm/s.
All the above findings, well assessable by ultrasound,
however, are indirect signs of the proximal SA pathology
only. The occlusive process itself is usually not easy to
visualize. The main reason for this is the limited access to
the vessel, located behind the clavicle. An absent signal
should therefore be cautiously interpreted, while stenoses
should be evaluated as soon as increased flow velocities
and turbulent flow can be detected. A subclavian steal
phenomenon can only be expected if a relevant SA stenosis
is present. A correlation study of duplex ultrasound-derived subclavian steal phenomenon grades and the degree
of SA stenosis, assessed by angiography, had the following
results: An SA stenosis of at least 60 % was found to produce abnormal VA Doppler flow signals in 90 % of cases.
Grade 3 subclavian steal phenomenon was associated with
SA occlusion in most of the observed cases (Yip et al. 1992).
It is important to notice that not every severe stenoocclusive process in the SA results in a reversed ipsilateral VA
flow. Normal VA flow directions might be found if other
collaterals, e. g., the inferior and external thyroid artery,
the internal mammary artery or intercostal and ascending
arteries, sufficientlycompensate for the SA pathology (Berguer et al. 1980). Sometimes the VA cannot serve as a
collateral vessel. This occurs in cases of an ipsilateral VA
occlusion, or anatomic VA variants such as a VA terminating as the posterior inferior cerebellar artery (PICA) or a VA
not originating from the SA but directly from the aortic
arch.
How do the other angiologic methods compare with
ultrasound in assessing the above dynamic flow patterns?
DSA has been considered to be the standard procedure in
diagnosis of subclavian steal phenomenon as it permits
direct visualization of the SA pathology as well as its hemodynamic effects. In particular the late arterial phase
images allow detection of the retrograde VA flow if contrast is injected into the nonaffected VA. In addition, DSA
allows assessment of other more complex vascular constellations, including the less frequently observed carotico-basilar, externo-vertebral, and carotico-subclavian
collateral pathways. Similar to ultrasound techniques,
DSA also allows functional or compression tests to be
performed. Its main diagnostic pitfall is the aortic arch
injection, which allows easy visualization of the SA pathology but may result in missing ipsilateral VA contrast
filling, suggesting VA occlusion. Also on selective contrast
filling of the nonaffected VA, an evaluation limited to the
early arterial phase might overlook a contralateral steal
phenomenon. Because of the low morbidity of the subclavian steal phenomenon, DSA should no longer be used as
the first method of choice.
TOF MRA, as a flow-sensitive technique, is not well
suitable for analysis of the subclavian steal phenomenon
as alternating flow patterns will result in an absent vessel
signal suggesting VA occlusion. Contrast-enhanced MRA
might suffer the same problem in grade 2 subclavian steal
phenomenon, but only if a net zero flow (identical systolic
retrograde and diastolic anterograde flow) is present. As
this type of ideal alternating flow is probably rare and a
preponderance of either systolic or diastolic flow occurs in
the majority of cases, contrast-enhanced MRA will be able
to evaluate the vessel integrity. However, confirmatory
statements regarding the flow direction within a vessel
cannot be made with either method. Phase-contrast MRA
can provide information on flow direction, but preselection of flow velocity parameters is required and is therefore rather susceptible to misinterpretation (Drutman et
Degree of Neurosonologic Difficulty: High
Case 28 Subclavian Steal Phenomenon in Subclavian Artery and Internal Carotid Artery Occlusion
330
al. 1994). A new dynamic MRI approach analyzing bolus
kinetics after gadolinium injection may allow a more adequate assessment by analyzing the circulation time of a
gadolinium bolus. In all eight patients with the subclavian
steal phenomenon a delay of peak enhancement was observed in the affected VA, ranging from 2 to 4 seconds,
whereas not all of the controls demonstrated a delay (Wu
et al. 2005). When using CTA, an appropriate contrast
Degree of Neurosonologic Difficulty: High
administration technique and post-processing method
needs to be applied because of the technique’sinability
to differentiate flow direction and itslack of hemodynamic
time sequences. Otherwise this may result in false-negative results as has been shown in a recent case report
(Ratanakorn et al. 2002). Larger series on the use of CTA
for subclavian steal phenomenon analysis have not been
reported.
Case 29
Cerebral Venous Thrombosis
331
Clinical Presentation
A 34-year-old woman presented with a 2-day history of
headache of fluctuating intensity. On the day of admission
the headache had worsened markedly and she had developed nausea and vomiting. No vascular risk factors were
known except for nicotine misuse and use of an estrogencontaining contraceptive. On admission the neurologic
examination revealed no focal neurologic deficits or meningeal signs.
Initial Neuroradiologic Findings
Cranial computed tomography (CCT) demonstrated no
ischemic parenchymal lesions. However, the right transverse sinus (TS) appeared hyperdense (Fig. B29.1).
Suspected Diagnosis
Cerebral venous thrombosis (CVT) of the right transverse
sinus.
Questions to Answer by Ultrasound Techniques
• Was the pulsatility index in the brain-supplying arteries
raised as an indirect sign of raised intracranial pressure?
• Were there signs of intracranial venous collateral drainage pathways?
(flow velocity: 29/25 cm/s) and in the left sphenoparietal
sinus (SphS) (flow velocity: 25/20cm/s). No flow signal
could be detected in projection of the right TS. The contralateral TS revealed raised flow velocities (flow velocity:
41/34 cm/s) (Figs.B29.2–B29.6).
Conclusion
The neurosonologic findings were suggestive of a right TS
occlusion andof an additional flow obstruction ofthe superior sagittal sinus (SSS). The left TS and SphS as well as both
BVRs appeared as the main alternative drainage pathways.
CT Angiography (CTA) (Day 1)
CTA confirmed a thrombosis of the distal SSS extending to
the right TS and sigmoid sinuses (SiS) down to the right
superior jugular bulb (Figs. B29.7, B29.8).
Clinical Course (1)
Intravenous heparin was initiated, aiming for a twofold
rise of partial thromboplastintime (PTT).In the following 2
days the patient’s headache completely resolved. Treatment was then changed from heparin to long-term oral
anticoagulation with phenprocoumon. The etiology of the
thrombosis remained unclear. There was no thrombophilia or underlying inflammatory disease. A follow-up
investigation was performed 90 and 180 days later.
Initial Neurosonologic Findings (Day 1)
Extracranial Duplex Sonography
B-mode sonography demonstrated normal findings in the
carotid and vertebral arteries.
Transcranial Duplex Sonography
All intracranial arteries showed normal flow signals with
regular pulsatility. Assessment of the intracranial veins
revealed a prominent flow signal in both basal veins of
Rosenthal (BVR) (flow velocity: left: 20/16cm/s, right: 31/
25 cm/s), in the right deep middle cerebral vein (DMCV)
Question to Answer by Ultrasound Techniques
• Was there evidence for recanalization of the occluded
sinuses over time?
Follow-up Neurosonologic Findings (Day 90)
Transcranial Duplex Sonography
The BVR now revealed an almost normal but not completely normalized flow signal on both sides (flow veloc-
Case 29 Cerebral Venous Thrombosis
332
ity: left: 19/15cm/s, right: 19/14cm/s) (Figs. B29.9,
B29.10). Low flow signals were also seen in the right
DMCV and in the left SphS (not shown). The TSs were not
examined.
Conclusion
Marked improvement of neurosonologic findings with diminished flow velocity in the venous collateral vessels
indicative of advanced recanalization of the right TS and
SSS.
Degree of Neurosonologic Difficulty: High
Question to Answer by Ultrasound Techniques
• Was there further evidence for normalization of venous
hemodynamics?
Follow-up Neurosonologic Findings (Day 180)
Transcranial Duplex Sonography
The BVR now showed a completely normal flow signal on
bothsides(flowvelocity:left:11/9cm/s,right:14/11cm/s).
No flow signals could be detected within the right DMCV
and the left SphS. Both TSs revealed normal flow signals
(flowvelocity:left:16/12cm/s,right:14/11cm/s)(Figs.
B29.11–B29.14).
Conclusion
Complete normalization of intracranial venous hemodynamics indicative of vessel restitution of the right TS and
SSS.
Clinical Course (2)
Clinical follow-up after 6 months was unremarkable. MRI
after 6 months revealed no parenchymal lesions. Time-offlight (TOF) MRA demonstrated a complete recanalization
of the right TS and the SSS (Fig. B29.15). Anticoagulation
with phenprocoumon was stopped.
Final Diagnosis
Extended CVT involving the distal SSS and the right TS and
SiS. There was complete recanalization after 6 months
while the patient was on oral anticoagulation.
Fig. B29.1 Unenhanced CCT, axial plane. No ischemic parenchymal
lesions. Note the hyperdense right transverse sinus (arrows).
Fig. B29.2 TCCS (transtemporal approach), left-sided insonation,
midbrain/thalamic plane. Mildly increased flow in the left basal
vein of Rosenthal (flow velocity: 20/16 cm/s).
Final Diagnosis
333
Degree of Neurosonologic Difficulty: High
Fig. B29.3 TCCS (transtemporal approach), right-sided insonation,
midbrain/thalamic plane. Increased flow velocity in the right basal
vein of Rosenthal (flow velocity: 31/25 cm/s).
Fig. B29.5 TCCS (transtemporal approach), left-sided insonation,
upper pontine plane. Flow velocity of 25/20 cm/s in the left sphenoparietal sinus.
Fig. B29.4 TCCS (transtemporal approach), right-sided insonation,
midbrain plane. Raisedflow velocity in the right deep middlecerebral
vein (flow velocity: 29/25 cm/s).
Fig. B29.6 TCCS (transtemporal approach), right-sided insona-
tion, oblique plane. Raised flow velocities in the left transverse sinus
(flow velocity: 41/34 cm/s).
Fig. B29.7 Intracranial CTA, sagittal MIP. Lack of contrast enhancement within the posterior part of the superior sagittal sinus (arrows).
Note a prominent basal vein of Rosenthal (arrow).
Fig. B29.8 Intracranial CTA, coronal MIP. Thrombus extending into
the superior jugular bulb indicated by a lack of contrast filling
(arrow).
Case 29 Cerebral Venous Thrombosis
334
Degree of Neurosonologic Difficulty: High
Fig. B29.9 TCCS (transtemporal approach), left-sided insonation,
midbrain plane. Left basal vein of Rosenthal demonstrating a nearly
normalized flow signal (flow velocity: 19/15 cm/s).
Fig. B29.11 TCCS (transtemporal approach), left-sided insonation,
midbrain plane. The left basal vein of Rosenthal in its proximal part
showing a normal flow signal (flow velocity: 11/9 cm/s). Note the
corresponding signal of the proximal P2-PCA (flow velocity: 63/
30 cm/s).
Fig. B29.10 TCCS (transtemporalapproach), right-sidedinsonation,
thalamic plane. Right basal vein of Rosenthal demonstrating a nearly
normalized flow signal (flow velocity: 19/14 cm/s).
Fig. B29.12 TCCS (transtemporalapproach), right-sidedinsonation,
thalamic plane. Normalized flow signal in the right basal vein of
Rosenthal (flow velocity: 14/11 cm/s).
Fig. B29.13 TCCS (transtemporal approach), right-sided insonation, oblique plane. The left transverse sinus now reveals a normal
flow signal (flow velocity: 16/12 cm/s).
Fig. B29.14 TCCS (transtemporal approach), left-sided insonation
oblique plane. The right transverse sinus can be visualized for the first
time. There is a normal flow signal (flow velocity: 14/11 cm/s).
Discussion
Clinical Aspects
Compared with arterial stroke, CVT is a rare condition
which predominantly affects young females. Recently,
the results of a large prospective multicenter study, the
International Study on Cerebral Vein and Dural Sinus
Thrombosis (ISCVT), which analyzed the clinical presentation, risk factors, and clinical course in patients with CVT,
have been published(Ferro et al. 2004). The study included
a total of 624 patients aged 16–86 years (mean age 39
years), recruited in 89 centers in 21 countries. The study
revealed a clear female predominance (74.5 % of cases).
Headache was the principal symptom in 88.8 %. The main
clinical signs were motor symptoms (37.2%) followed by
papilledema (28.3 %), mental disorders (22 %), and aphasia
(19.1 %). Stupor or coma was present in 13.9% of patients.
Seizures—usually focal seizure with secondary generalization—occurred in 39.3 % of cases. On MR or CT imaging,
venous infarction was seen in 46.5 %. Intracranial bleeding
was found in 39.3 %. Only 37.1% of patients were without
detectable parenchymal pathology. The most frequently
affected vessel was the SSS (62 % of cases) followed by the
lateral sinus (TS and SiS) on the left in 44.7 % of cases and
on the right side in 41.2 %. The deep cerebral venous system was afflicted in 10.9 % and the cortical veins in 17.1%.
Only rarely, a thrombus of the cavernous sinus (CS) was
observed (1.3%). Thrombophilia was found in 34.1%,
which was inherited in most cases. An antiphospholipid
antibody syndrome wasthe main acquired disease in 5.9 %.
Other probable relevant causes were hematologic disorders such as general anemia, occurring in 12 %, and malignancy-related disorders in 7.4%. In females younger than
50 years of age, pregnancy and the puerperium were the
presumed cause in 6.3 % and 13.8%, respectively. Within
this subgroup, oral contraceptives were taken by 54.3 % of
patients. In 12.5% of cases no risk factor could be identified.
Generally, the clinical outcome at a median of 16 months
was favorable. 57.1 % of patients were completely free of
symptoms. Considering the modified Rakin Scale (mRS),
minor (mRS: 1), mild (mRS: 2), moderate (mRS: 3) and
severe impairment (mRS: 4 or 5) was seen in 22 %, 7.5 %,
2.9 %, and 2.2 %, respectively. Death occurred in 8.3 % of
cases. Recurrence was a minor concern affecting only
2.2 % of patients. Late epilepsy was seen in 10.6%. An unfavorable outcome was associated with central nervous
system (CNS) infection, cerebral deep venous thrombosis,
malignancy, age > 37 years, mental disorder, coma, intracranial bleeding, and male sex.
The majority of patients were initially anticoagulated
(83.3%).Intravenousheparinwasthemainlymethod
used (64 %). Low-molecular-weight heparin was given to
34.9 %. A trend toward a better outcome concerning death
and dependency was seen in patients who were anticoagulated (12.7 %) compared to those who did not receive
Discussion
Fig. B29.15 Intracranial 3D TOF MRA, coronal MIP. Complete recanalization of the superior sagittal sinus and right transverse sinus after
6 months. Note the variation in the confluence of sinuses, with the
superior sagittal sinus predominantly draining into the left transverse sinus, and the straight sinus predominantly draining into the
right transverse sinus.
anticoagulation (18.3 %). This difference was not however
statistically significant (Ferro et al. 2004).
The best treatment strategy remains controversial (Einhäupl et al. 1991, de Bruijn and Stam 1999). In patients with
proved hypercoagulability syndrome, anticoagulation
therapy is generally recommended for a period of 6–12
months. In patients with idiopathic CVT, a 3–6month
period seems adequate. However, the ISCVT study demonstrated that in clinical practice up to 20 % of patients do
not receive anticoagulation. This is remarkable as in patients predicted to have a poor prognosis the thrombotic
process may, without anticoagulation, progress rapidly
leading to a critical stage in the disease course.
On analyzing the ISCVT data on patients withearly intracranial hemorrhage the highest risk for death or dependency after 6 months was found in older men presenting a
motor deficit who suffered from thrombosis of the deep
cerebral venous system or the right lateral sinus (Girot et
al. 2007). In these patients, a standard heparin regimen
might be insufficient and local fibrinolytic therapy or other
aggressive recanalization method has to be considered.
Currently, apart from case reports and small clinical series,
there is no other positive evidence to support the safety of
systemic thrombolysis (Canhao et al. 2003).
Angiologic and Anatomic Aspects
Catheter angiography has been the gold standard in diagnosing CVT for many years. Until recently it was the
method of reference in cases with equivocal MRI/MRA
335
Degree of Neurosonologic Difficulty: High