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asymptomatic or may present with vague abdominal pain. Patients with thrombus limited to the main portal vein may
be asymptomatic. As the thrombus burden increases and extends into the superior mesenteric vein (SMV) and
mesenteric veins, patients may present with severe abdominal pain related to venous ischemia of the bowel or the ileus or
infarction. With chronic PVT, patients will present with symptoms of portal hypertension, including splenomegaly,
thrombocytopenia, esophageal and/or mesenteric varices, or bleeding. Ascites is less likely to occur in patients with
isolated PVT compared with those with concomitant cirrhosis. Prognosis is based on the extent of thrombosis and the cause
of thrombosis. Patients with isolated PVT have a better prognosis than those with PVT and cirrhosis, due to preserved liver
function.
The diagnosis of PVT is primarily made with imaging. In most cases, liver function tests remain normal due to flow
compensation. The portal vein is easily identified on ultrasound, and flow analysis with Doppler can be performed. Partial
or complete thrombosis can be observed with both gray-scale and Doppler imaging. On gray-scale imaging, solid echoes
are seen within the vessel. If the thrombus is occlusive, no flow is observed. In cases of chronic thrombosis, cavernous
transformation can be seen as multiple collateral vascular channels within the porta hepatis. Ultrasound is fast, relatively
inexpensive, and readily available and causes little to no patient discomfort. Sensitivity for PVT diagnosis ranges from
66% to 100%. Evaluation of the mesenteric veins is limited by the overlying bowel, which prevents visualization. While
not available in all centers, contrast-enhanced ultrasound is superior to standard ultrasound and Doppler for the
characterization of PVT. Contrast-enhanced CT can demonstrate the extent of thrombus, as well as the potential
complications such as bowel and mesenteric edema (Fig. 33.6). Spontaneous portosystemic shunts such as a splenorenal
shunt and other upper abdominal varices can also be characterized. A bland thrombus will appear as a complete or
incomplete filling defect within the vessel. If tumor thrombus is suspected, pre- and postcontrast imaging should be
obtained to determine if there is enhancement of the thrombus. Bland thrombus will not enhance, while tumor thrombus
will enhance on postcontrast images be cause of internal vascularity. While contrast-enhanced CT has many advantages, its
role may be limited in patients with renal insufficiency. MRI is 98%e100% sensitive in the detection of portal thrombosis
[18]. When performed with contrast, the extent of thrombus can be demonstrated; however, as with CT, the use of contrast
may not be possible in patients with impaired renal function. MRI is particularly useful in the setting of HCC and
tumor thrombosis. Characterization of liver lesions is superior with MRI and is the preferred modality for therapy planning;
however, patient cooperation is necessary, as images are more susceptible to respiratory artifact. Conventional
splenoportography, mesenteric angiog raphy, or wedged carbon dioxide portography is rarely needed for diagnostic
purposes alone.
(A) (B)
FIGURE 33.6 Portal vein thrombosis. (A) Coronal contrast-enhanced CT showing thrombosis of the portal vein (arrowheads) and stranding of
the mesentery representing edema (arrows). (B) Transjugular venogram of the portal vein and superior mesenteric vein shows diffuse irregularity of the
vessels with filling defects and stasis of contrast.
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The goal of treatment in PVT is to restore flow and prevent the consequences of portal hypertension, including bleeding
and, if acute, intestinal infarction. Initiation of anticoagulation within 30 days of symptoms is considered first-line therapy
in patients with acute PVT. Recanalization of the portal vein can be seen in up to 35% of patients and may take up to
4e6 months after the initiation of therapy. Patients with prothrombotic conditions may require lifelong anticoagulation. In
patients with more severe acute disease, direct catheter-based pharmacologic or pharmacomechanical thrombolysis can be
performed via a transhepatic or transjugular approach, with up to 75% of patients showing some degree of lysis. There is an
increased risk of significant bleeding if thrombolysis is performed via a transhepatic approach. Indirect thrombolysis is
performed by infusing a thrombolytic agent into the superior mesenteric artery. Indirect thrombolysis is more effective than
systemic anticoagulation with regard to improving flow through the portal vein [19]. Surgical thrombe ctomy is not
recommended because of the risk of recurrent thrombosis and surgical morbidity and mortality. Although technically
challenging in PVT, transjugular intrahepatic portosystemic shunt (TIPS) has been used successfully, even in cases of
cavernous transformation. Studies have shown that TIPS is a safe and feasible alternative therapy for selected patients with
chronic PVT and cirrhosis. Several techniques have been described to increase the chance of performing a successful TIPS,
including transhepatic and transsplenic portography. Successful placement of a TIPS reduces the portosystemic pressure
gradient and can prevent variceal bleeding [20]. Once a TIPS is in place, direct thrombolysis of the clot can be performed
using the previously described techniques. Direct thrombolysis of PVT is superior to indirect thrombolysis in restoring
flow in the portal vein [21].
HEPATIC VEIN THROMBOSIS
Hepatic vein thrombosis, also known as BuddeChiari syndrome (BCS), is a rare disorder that involves obstruction of the
venous outflow of the liver into the IVC. Primary BCS is an intrinsic vascular process, which is further classified by the
level of obstruction, which can be within the hepatic veins or the intrahepatic portion of the IVC. Secondary BCS is due
to extrinsic compression or invasion of the vessels by extravascular lesi ons, including benign and malignant tumors,
abscesses, and cardiac and pericardial disease [22,23]. Hypercoagulable states, both inherited and acquired, are the most
common risk factor for BCS [24]. Other risk factors include pregnancy, malnutrition, OCP use, Behçet disease,
hypereosinophilic syndrome, and ulcerative colitis [23,25,26].
Occlusion of the hepatic venous outflow results in increased sinusoidal and portal venous pressure. As the portal
pressure rises, porta l vein flow to the liver decreases, as there is increased hepatic congestion. Most cases of BCS are
subacute or chronic and have a slow progression. The portal hypertension is compensated by the formation of varices.
Ascites will also begin to form because of the portal hypertension. If the course of the disease is acute, there is inadequate
compensation, which results in hypoxic hepatocellular damage and fibrosis. If the process is diffuse it may cause fulminant
hepatic failure known as fulminant BCS [27].
The fulminant form of BCS accounts for 5% of cases [28]. Patients will present with abdominal pain and
encephalopathy. Lab studies will reveal elevated hepatic enzymes, coagulopathy, and hyperbilirubinemia [29]. There may
be associated renal failure due to compromised renal vein outflow. The liver will be enlarged due to congestion, and ascites
will be present [30]. Acute BCS (20% of cases) [28] has a similar presentation without fulminant hepatic failure; however,
hepatic congestion and necrosis are also seen histologically [31]. Subacute BCS is the most common form and, together
with chronic BCS, accounts for 60% of cases [28]. These patients will typically present with symptoms of portal
hypertension, including ascites and splenomegaly. Renal failure can be seen in up to 50% of patients with chronic BCS
[30]. Esophageal bleeding is not seen in subacute BCS but can be seen in 5%e15% of patients with the chronic form [30].
BCS may be asymptomatic in up to 5%e15% of cases. This can be attributed to a decreased obstructive burden relative to
more severe disease [23,32,33].
Imaging plays a key role in the diagnosis of BCS. Conventional ultrasound will demonstrate hepatomegaly. The IVC
may be compressed or stenotic with enlarged intrahepatic collateral vessels. The caudate lobe vein, which drains separa tely
and directly into the IVC, may be enlarged. The hepatic veins may have inte rnal echoes or be replaced with a fibrous
echogenic cord [23,34e38]. The hepatic parenchyma may demonstrate regenerative nodules [38,39]. Doppler interrogation
of the hepatic veins will show absence of or reversed flow. The visualization of subcapsular or intercostal draining veins is
highly sensitive and specific for BCS [30]. The portal vein can also be assessed for patency and direction of flow.
Extrahepatic findings such as ascites and splenomegaly are easily seen with ultrasound.
Contrast-enhanced CT imaging can have a variety of findings. The liver parenchyma can have a normal appearance or
show patchy enhancement due to stasis of flow within the sinusoids [37,40,41]. The caudate lobe will be enlarged, and the
IVC may be compressed [35,40,42]. In acute BCS the portal vein may or may not be thrombosed [42,43]. With chronic
BCS, the liver can have a cirrhotic appearance with regenerative nodules that demonstrate patchy enhancement (Fig. 33.7
).
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(A) (B)
(C) (D)
FIGURE 33.7 Hepatic vein thrombus (BuddeChiari). (A) Contrast-enhanced axial MRI of the liver showing heterogeneous enhancement of the
parenchyma with regenerative nodules. (B) Delayed contrast-enhanced axial MRI showing lack of enhancement of hepatic veins (arrowheads) with
collateral flow in the right hepatic lobe (arrow) adjacent to an intrahepatic hemangioma. (C) Transjugular right hepatic venogram shows occlusion with no
flow into the inferior vena cava (IVC) and intrahepatic collaterals. (D) Post-stent-placement venogram shows brisk flow through the stent and into the IVC
and right atrium.
There will be associated upper abdominal varices [42]. The anatomic findings made with CT are similar on MRI.
Three-dimensional contrast-enhanced MRI angiography will show absence of flow in the occluded hepatic veins and the
presence and direction of flow in collateral vessels, portal vein, and IVC [44].
Catheter venography is considered the reference standard for diagnosis [34]; however, it is usually reserved for cases in
which a histologic sample is required via transvenous biopsy, or an endovascular therapy is planned. Catheter venography
has the advantage of being able to precisely depict the level of obstruction and to determine the hemodynamic significance
by measuring intravascular pressures. A combination of intravascular techniques may be needed depending on the level of
obstruction to relieve congestion and restore hepatic venous outflow. Such techniques include venoplasty, stent placement,
catheter-directed thrombolysis, and TIPS (Fig. 33.7) [45e51]. The long-term durability of angioplasty and stent placement
for treatment of isolated hepatic vein and IVC webs, stenosis, and occlusion is not proven and is limited to case reports
[31]. If these interventions fail, the next endovascular therapy is TIPS. TIPS creation will relieve hepatic congestion and
portal venous pressure by shunting portal blood into the suprahepatic IVC [24]. Technical success rates are reported at
90%, with clinical success in greater than 75% [45,49,52]. Long-term anticoagulation may be required to maintain shunt
patency, particularly in those patients with underlying hypercoagulable state [24,25,45].
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The surgical management of BCS includes membrane resection; IVC reconstruction with a pericardial patch;
portosystemic, mesoatrial, and portoatrial shunt creation; and liver transplant [53e56]. If there is obstruction of the IVC, a
combined endovascular approach with IVC stent may be necessary for the patency of a surgically created shunt [57].
Patients with fulminant BCS should be immediately listed and undergo emergency liver transplant as soon as possible [58].
Transplant can also be considered in patients with chronic BCS and associated cirrhosis [24,58].
RENAL VEIN THROMBOSIS
Thrombosis of the renal veins ( Fig. 33.8) may be bland or due to tumor infiltration. In adult patients, bland thrombus
is most often associated with nephrotic syndrome, but can also be seen in systemic lupus erythematosus (SLE),
antiphospholipid syndrome, and other hypercoagulable states. Newborns may develop renal vein thrombosis (RVT) from
dehydration, asphyxia/fetal distress, or coagulation abnormalities. Tumor thrombus is most likely to be caused by advanced
renal cell carcinoma (RCC) and can be seen in 12%e19% of patients with RCC. Tumor thrombus is associated with a poor
prognosis. Clinical manifestations may include abdominal pain, hematuria, nausea, vomiting, and fever. If there is bilateral
involvement, patients may present with acute renal failure [59].
Anticoagulation is the first line of therapy in RVT. The goal of therapy is relief of venous obstruction and preservation
of renal function. The use of catheter-directed thrombolysis has been reported with success in patients with RVT and acute
renal failure. Several catheter-based techniques have been described, including indirect thrombolysis via a transarterial
approach and direct thrombolysis via a transvenous approach. Both infusion-based and pharmacomechanical thrombolysis
endovascular therapies have been used for direct thrombolysis. These techniques have been used in both native and
transplant kidneys. Complications are similar to other thrombolysis techniques used in other parts of the body and include
bleeding, thromboembolization, and vascular access complications [59,60].
SEPTIC THROMBOPHLEBITIS
Septic thrombophlebitis is characterized by venous thrombosis with associated bacterial or fungal infection. Superficial or
deep veins may be involved. Presentation of septic thrombophlebitis can range from a benign course affecting localized
superficial veins to severe systemic infections resulting in shock and death. Prompt recognition and treatment are necessary
to prevent progression and severe complications. Distinct conditions have been described based on the vein and associated
organ involved. One such entity is Lemierre syndrome, which is septic thrombophlebitis of the internal jugular veins.
Regardless of the location of the involved vessel, the severity of disease is distinguished as either simple or suppurative,
with suppurative indicating purulence.
Simple phlebitis of the superficial veins is most often caused by intravenous (i.v.) catheters but may also be caused by
any break in the skin. Once the infective organism has entered the vein and proliferates, endothelial damage ensues,
resulting in inflammation and thrombosis. While the most common organism is Staphylococcus aureus, other organisms
(A) (B)
FIGURE 33.8 Left renal vein thrombosis. (A) Coronal contrast-enhanced CT showing filling defect in the left renal vein extending into the inferior vena
cava (arrows). (B) Transjugular venogram of the left renal vein (different patient) shows chronic occlusion with collateral flow.
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have been implicated. Patients will present with pain and erythema, which may spread along the course of the infected
vessel. Treatment of superficial simple phlebitis starts with the removal of the i.v. catheter if present, followed by
antibiotics. Suppurative superficial thrombophlebitis is a rare condition that can be complicated by septic embolization,
most commonly to the lungs, which can lead to sepsis, hypoxia, and death. Broad-spectrum antibiotics with coverage of
common skin flora should be promptly initiated. Anticoagulation is not routinely used unless there is extension into the
deep veins. Surgical resection is reserved for cases refractory to antibiotics [61,62].
Septic phlebitis of the deep venous system involving the SVC and IVC is primarily related to the use of central venous
catheters. Burn victims and patients receiving total parenteral nutrition are at increased risk. Patients will present with
fever, often without pain or swelling, at the site of catheter insertion. Depending on the extent of thrombosis, extremity
edema may be present. Workup begins with basic lab studies, including complete blood count, chemistry, and coagulation
profile. Blood cultures should also be obtained. If catheter-related infection is suspected, cultures should be drawn from
both a peripheral site and the central catheter for comparison. A catheter tip culture can be helpful; however, caution must
be used when removing an infected central catheter as there may be adherent septic thrombus, which could embolize.
Lemierre syndrome is a rare disease, which occurs in 0.8e1.5 per million people annually, with a mean age of 20. The
natural history of this disease begins with an oropharyngeal infection, which spreads into the lateral pharyngeal space and
subsequently the carotid sheath. The time course from initial infection to septic thrombophlebitis is 1e3 weeks. The
organism most commonly implicated is Fusobacterium necrophorum, which is a normal oropharyngeal flora; however,
multiple other bacteria have been implicated. Patients will present with sore throat, neck pain, and fever. On physical exam
they may have asymmetric neck swelling and appear septic [63].
Ultrasound is the imaging modality of choice for the extremities as well as the internal jugular veins. In the setting of
positive blood culture and ultrasound evidence of DVT, a diagnosis of septic thrombophlebitis can be made. The SVC and
IVC are at times suboptimally evaluated on ultrasound, as are the large veins in the pelvis. This is due to overlying
structures, which attenuate the ultrasound beam and limit the acoustic window. Contrast-enhanced CT is better suited to
look for thrombus in these structures. CT will show a filling defect in the affected vessel and may show surrounding
inflammatory change. CT may also show the inciting inflammatory process and demonstrate complications such as septic
emboli. Diagnosis can also be made with MRI and MR venography (MRV); however, this modality is more frequently
used in cases of dural sinus thrombosis. Diagnostic venography is not performed in the setting of septic thrombophlebitis
unless there is an intention to treat.
Antibiotics and anticoagulation are the primary treatment for deep venous septic thrombophlebitis. Data on
catheter-directed therapy in the setting of septic thrombophlebitis are limited to case reports. Intravascular manipulation
carries a risk of septic embolization and systemic sepsis. Mechanical thrombectomy has been reserved for those patients in
whom anticoagulation was contraindicated, or if there was progression of symptoms while adequately anticoagulated. The
AngioJet device has been successfully used in cases of deep venous septic thrombophlebitis; however, operators should
remain cautious and prepar ed to manage complications [64].
CEREBRAL VENOUS THROMBOSIS
Cerebral venous thrombosis (CVT) refers to the development of thrombus in a variety of intracranial venous structures,
including the dural venous sinuses and cortical veins. Estimates of the incidence of CVT are between 2 and 15.7 patients
per million annually [65e 68]. Recent studies indicate a trend toward higher incidence of this relatively rare condition,
probably secondary to increased clinical awareness, improved noninvasive diagnostic imaging techniques, and more
inclusive retrospective review strategies [65,67]. The largest prospective study of CVT as of this writing, the International
Study on Cerebral Vein and Dural Sinus Thrombosis (ISCVT), published in 2004, reports an increased incidence of
intracranial thrombosis in younger female patients. The study found a mean age at presentation of 39.1 years, and 78% of
patients were under the age of 50 [69].
Intracranial venous thrombosis is thought to account for approximately 0.5%e1% of all infarcts [70]. CVT occurs in a
heterogeneous cohort of patients with a set of risk factors that can be generally categorized as acquired or inherited
prothrombotic states. The primary acquired risk factors reported in patients with CVT inclu de the following: pregnancy,
puerperium, dehydration, malignancy, exogenous hormones, trauma, surgery, systemic inflammatory disorders, and
infection [66,69,71]. Inherited prothrombotic states that demonstrate a strong association with CVT include deficiency of
antithrombin III, protein C, and protein S; factor V Leiden gene mutation; prothrombin G20210A mutation; and
hyperhomocysteinemia, among other less common entities [72e81]. CVT is attributed to approximately 2% of
pregnancy-associated infarcts [82]. An additional risk factor for younger women is the use of OCPs [66,83]. The large
majority of nonpregnant women with CVT are found to be OCP users and the risk of CVT in OCP users is greater if these
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patients also have an underlying inherited prothrombotic condition [66]. Among children, the most commonly affected are
neonates who are at increased risk secondary to birth trauma and dehydration [84e86]. In pediatric patients, CVT is more
commonly associated with infection [84e86]. Despite the many known risk factors for CVT, approximately 15% of cases
remain idiopathic [71].
CVT often presents a diagnostic challenge because this uncommon condition generates a broad spectrum of clinical
presentations ranging from an isolated headache to coma and death. Therefore, clinical suspicion should remain high in
younger female patients with a combination of the aforementioned risk factors who present with nonspecific clinical
symptoms. The most common clinical presentations of CVT are manifestations of increased intracranial pressure and
those associated with venous ischemia. These symptoms include the following: headache, seizure, papilledema, altered
consciousness, and focal neurologic deficits (primarily including paresis, aphasia, diplopia, and visual loss). The time of
onset of symptoms is variable and includes acute, subacute, and more indolent presentations. In the ISCVT cohort the
majority (56%) of patients presented with symptom onset in the subacute period of >48 h to 30 days, while 37% presented
with acute symptoms in <48 h and only 7% presented with more chronic symp toms after 30 days [69,71]. This variable
onset of a protean set of symptoms often delays diagnosis and initiation of treatment. In contrast to arterial infarcts, CVT
rarely presents as a specific “stroke-like” syndrome [71].
Diagnosis of CVT relies on recognizing the high-probability clinical scenarios and having a low threshold for obtaining
the appropriate imaging workup. While there is no agreed-upon imaging algorithm, three modalities are considered the
standard in diagnosis: MRI with MRV, CTV, and catheter-based venography [66]. At this writing, no confirmatory
laboratory test has been developed that can confidently rule out CVT [66]. An elevated D-dimer supports the diagnosis of
CVT, with a 2012 meta-analysis showing a 94% sensitivity and a 90% specificity [87]. However, the high rate of false
negative results in patients with a limited thrombus burden and an unclear set of clinical symptoms precludes its use as a
screening tool (Fig. 33.12) [87].
In practice, contrast-enhanced MRI of the brain is the mainstay imaging modality for confident diagno sis of CVT,
provided there is no contraindic ation to gadolinium-based contrast agents, such as pregnancy [71,88,8 9]. Volumetric
postcontrast imaging allows for a more direct luminal evaluation of the superficial and deep dural venous sinuses than
provided by noncontrast MRV. This sequence will often demonstrate a clear, low-signal filling defect in a mildly expanded
venous sinus, providing a speci fic diagnosis of CVT (Fig. 33.9). Noncontrast sequences obtained concurrently can be used
to corroborate the postcontrast findings and characterize signal changes within the thrombus, which will vary depending on
the age of the clot (Fig. 33.10). MRI sequences that are sensitive to blood products (gradient and susceptibility-weighted
imaging [SWI]) can add confidence to the diagnosis, with most acute and chronic thrombi generating marked signal loss,
which stands out from the surrounding venous flow-related signal voids and exaggerates the size of the throm bus [90e93].
SWI is particularly useful in the detection of cortical venous thrombos is because the “blooming” (or exaggerated
susceptibility-related signal loss) effect of the thrombus makes even small thrombosed cortical veins conspicuous [94]
(Fig. 33.11B).
An important secondary benefit of MR imaging is its ability to demonstrate the upstream effects of a venous occlusion,
which can manifest as a variety of parenchymal signal abnormalities. Parenchymal findings range from subtle gyral
swelling to vasogenic edema and ultimately venous infarction, which may hemorrhage (Fig. 33.11). A subset of venous
infarcts will develop irreversible cytotoxic edema and restricted diffusion; however, this occurs less commonly than with
arterial infarcts [71].
Noncontrast MRV is an imaging technique that relies on signal generated from flow within patent venous structures,
which has the benefit of not requi ring contrast administration. When flow-related signal is identified within all of the major
dural venous sinuses, sinus thrombosis can be confidently excluded. Likewise, noncontrast MRV can verify the loss of
flow within a dural sinus that was suspected on noncontrast CT or MR images. However, the interpretation of noncontrast
MRI without MRV can be misleading because the signal changes in thrombi vary with age and composition and can be
mistaken for flow as the thrombus ages. Likewise, noncontrast MRV images are subject to misinterpretation in isolation.
These sequences often lead to indeterminate interpretations due to anatomic variations, slow flow, and artifact.
Congenitally small or absent sinuses, turbulent flow, extrinsic mass effect, and diminished sinus flow can all mimic
occlusive or partially occlusive thrombus. Thus, contrast-enhanced MRI with volumetric postcontrast sequences often
provides the most confident MR diagnosis of CVT when clinically feasible.
CTV can also effectively demonstrate filling defects in the dural venous sinuses and can be obtained rapidly in most
hospital settings. Likewise, CTV can be performed in patients with contraindications to or inability to tolerate MRI.
Standard venous timing of contrast results in dense opacification of the dural sinuses and produces a conspicuous “empty
delta” sign-filling defect in the setting of a thrombus as well as adjacent dural enhancement and venous collateral drainage
[95,96]. The spatial and contrast resolution of CTV allows for sensitive and specific CVT diagnosis in many cases.
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(A) (B) (C)
(D) (E)
FIGURE 33.9 Contrast-enhanced MRI and MR venography confirm the diagnosis of cerebral venous thrombosis (CVT). (A) Sagittal, (B) axial, and
(C) coronal T1-weighted volumetric postcontrast sequences demonstrate low-intensity filling defects within the superior sagittal (SSS) and transverse
sinuses (arrows), consistent with extensive thrombus. (D) Anteroposterior (AP) and (E) AP oblique phase-contrast MR venograms demonstrate flow in the
SSS and absence of flow in the right transverse sinus (asterisks) consistent with nonocclusive and occlusive sinus thrombus, respectively.
The downside for CTV includes the risk of contrast-induced nephropathy, radiation exposure, and a less sensitive exam for
the evaluation of concurrent brain parenchymal abnormalities. While cases of significant parenchymal edema, mass effect,
and/or hemorrhagic venous infarct may be apparent on CT, more subtle cases of parenchymal injury are often
inconspicuous. Noncontrast CT imaging will demonstrate increased density (known as the delta sign when viewed in cross
section) in only approximately 33% of CVT cases [71]. The majority of CVT cases will be missed by noncontrast CT alone
and therefore its roll is limited without contrast, and is inadequate as a screening exam [66,71].
Catheter-based intraarterial angiography can detect absences of a dominant cortical vein or venous sinus or provide
indirect visualization of a partially occlusive endoluminal filling defect, allowing for a specific diagnosis of CVT. These
venous occlusions can also present with associated findings such as delayed venous outflow, venous collateralization, and
corticovenous reflux. Catheter-based intraarterial angiography has superior spatial and temporal resolution compared with
MRI or CT; however, it requires an invasive procedure and anesthesia to perform. Although safe when performed at
experienced centers, catheter-based angiography carries small risks of embolic infarct, vascular injury, hemorrhage
(intracranial and groin), infection, allergic reaction to contrast, or complications associated with anesthesia. The risks of
angiography are generally warranted only in the setting of an unclear diagnosis following noninvasive imaging and when
an inte rventional treatment is being considered. Interpretation of venous phase angiography can be challenging in certain
cases because of a wide variety of developmental venous variations, such as sinus hypoplasia or aplasia, which can be
mistaken for CVT [97]. Currently catheter angiography is infrequently used in the diagnosis of CVT [71].
Once a diagnosis of CVT has been confirmed, medical management is typically initiated. The goals of medical
management include the following: to prevent further thrombus propagation, especially into small cortical veins, which can
result in venous infarcts; to promote sinus recanalization; and to prevent rare systemic embolic events such as PE. The
primary treatment for CVT is medical management with dose-adjusted subcutaneous LMWH or intravenous UFH followed
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(A)
(C) (D)
(B)
FIGURE 33.10 Imaging characteristics of transverse sinus thrombus on CT and MRI at different ages. (A) Axial noncontrast CT scan demonstrating
increased density within the right transverse sinus representing acute thrombus (arrows). (B) Axial gradient noncontrast MR image showing prominent
susceptibility-related signal loss (“blooming artifact”) along the course of the right transverse sinus secondary to the paramagnetic effects of
deoxyhemoglobin in an acute thrombus (arrows). (C) Axial T2-weighted image demonstrating hyperintensity within the right transverse sinus secondary
to methemoglobin within a late subacute thrombus (arrows). (D) Axial noncontrast T1-weighted image illustrating hyperintensity secondary to T1
shortening effects of methemoglobin in a late subacute thrombus (arrows).
by transition to oral anticoagulation with warfarin [66,98e100]. Once the patient has stabilized after the acute phase of
CVT, oral anticoagulation with warfarin is recommended for 3e6 months for CVT secondary to a defined transient risk
factor such as infection. For cases of idiopathic CVT or CVT secondary to mild thrombophilia, such as heterozygous factor
V Leiden or prothrombin G20210A mutations and high plasma levels of factor VIII, anticoagulation for 6e12 months is
recommended [98,101]. Chronic anticoagulation is reserved for patients with recurrent idiopathic CVT and with severe
thrombophilias, which increase the risk of recurrence, such as antithrombin, protein C or protein S deficiency, homozygous
factor V Leiden or prothrombin G20210A mutations, antiphospholipid antibodies, and combined abnormalities [98,101].
Regardless of etiology and duration, an international normalized ratio goal of 2e3 is recommended [66]. At this writing,
there is inadequate evidence to support the use of direct oral anticoagulants (DOACs) in the treatment of CVT.
The use of this or similar anticoagulation paradigms is supported by four clinical trials [101e104]. These trials,
combined with several observational studies, form the foundation for the current set of treatment recommendations for
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(A) (B) (C)
FIGURE 33.11 Hemorrhagic venous infarct secondary to vein of Labbe thrombosis. (A) Axial CT image showing an acute left temporal hematoma with
surrounding vasogenic edema, local mass effect, and focal hyperdensity within the thrombosed left cortical vein of Labbe (arrow). (B) Axial gradient
image illustrating susceptibility-related signal loss (blooming) secondary to deoxyhemoglobin within the acute temporal hematoma and the acute thrombus
in the vein of Labbe (arrow). (C) Axial contrast-enhanced T1-weighted MR image demonstrating low signal within the acute hematoma and a filling
defect within the thrombosed left vein of Labbe (arrow).
FIGURE 33.12 Cerebral venous anatomy and most frequent locations (%) of cerebral venous and dural sinus thrombosis as reported by the International
Study on Cerebral Venous and Dural Sinus Thrombosis (ISCVT) (n ¼ 624) [69].
CVT, which are published by several societies as consensus guidelines [66,98,105,106]. Whil e the base of evidence is
relatively small, these groups draw similar conclusions and prescribe similar treatment paradigms that have become the
current standard of care. The treatment regimen for pediatric patients is similar to the adult strategy with appropriate dose
adjustments. This practice is based on less evidence, as there are no randomized prospective trials available to guide
management.
An important factor to consider when treating CVT patients is the safety of anticoagulation in the setting of intracranial
hemorrhage. While it may seem counterintuitive to anticoagulate a patient with an intracranial hemorrhage, anticoagulation
in the setting of CVT with intracranial hemorrhage, either intraparenchymal or subarachnoid, seems to be both safe and
efficacious [34]. This practice is supported by both the findings of the Berlin and Dutch randomized controlled trials and
several observational studies [107e110]. Mechanistically this practice is supported by the notion that deceasing the
propagation and extent of thrombus burden should decrease the amount of venous backpressure and thus decrease the
chance of expanding or generating new hemorrhagic venous infarct.
Beyond the medical management of CVT with anticoagulants, if a primary cause for the thrombosis is apparent, such as
mastoiditis or neoplasm, treatment of the primary etiology should be initiated. Likewise, if the patient is suffering from the
secondary effects of thrombus-induced venous hypertension or infarct such as vision loss, seizure, or intracranial mass
Thrombosis of the Venous Vasculature: Diagnosis and Management Chapter | 33 487
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effect, treatment of these symptoms should be initiated. In patients who present with acute-phase seizure or who have
hemorrhagic lesions on their admission imaging, current recommendations are to continue antiepileptic treatment for 1 year
[98]. In CVT patients who develop severe chronic headaches, repeat MRI and MRV should be performed to evaluate for
thrombus propagation and secondary signs of increased intracranial pressure. In such patients, or in patients with negative
repeat imaging, lumbar puncture may be necessary to exclude chronically elevated intracranial pressure, which should
subsequently be treated [111e113]. In the group of acute CVT patients presenting with severe intracranial hemorrhage
with herniation, emergent surgical decompression may be required.
Endovascular thrombectomy and/or thrombolysis may be an effective adjunct to systemic anticoagulation in patients
who demonstrate symptom progression despite medical manag ement.
As of this writing there have been no randomized controlled trials supporting the use of interventional treatment of
CVT. However, some observational studies show a trend toward improved outcomes in patients with significant thrombus
burden and baseline poor prognosis [98,114,115].
The goal of endovascular therapy is to reestablish some degree of flow within the occluded sinus. If a channel of flow
can be established via thrombolytic injection, or mechanical disruption of the clot, the flowing blood has the potential to
lyse or stabilize the residual thrombus. These techniques confer a significant risk of sinus or adjacent structure damage,
which can lead to intracranial hemorrhage or venous infarction. Therefore, endovascular interventions should be reserved
for the most severe cases and be attempted only by experienced practitioners at centers with appropriate neurosurgical and
neurocritical care support. At the time of this publication the results of the TO-A CT trial (Thrombolysis or Anticoagulation
for Cerebral Venous Thrombosis) are pending. This trial should provide guidance from a randomized controlled cohort on
the role of endovascular treatment in CVT [116].
The large majority of CVT patients have good outcomes with standard medical management. Long-term follow-up of
the ISCVT cohort (493 patients followed for a median of 16 months) showed modified Rankin Scale (mRS) scores of 0 or
1 (asymptomatic or no significant disability) in 79% of patients, almost all treated with anticoagulation [69]. However,
CVT was associated with death or dependency (mRS > 3) in 13.4% of patients at their median 16-month follow-up despite
treatment [69].
In the acute phase of CVT approximately 5% of patients die [69,117]. In this subset of severe patients, death was
usually secondary to focal mass effect from hemorrhage resulting in herniation and diffuse cerebral edema [71,118,119].
The ISCVT study identified multiple predictors of death and dependence ( Table 33.3) [69,120]. In the subset of patients
who presented with intracranial hemorrhage, 21% had died or become dependent at 6-month follow-up [69,121]. Overall,
the youngest and oldest CVT patients have the poorest outcomes. In a subset analysis of elderly CVT patients only 47%
made a complete recovery, 22% were dependent, and 27% had died at long-term follow-up [122]. Likewise, in children
and neonates the delayed complication, dependency, and death rates are all higher than in adults [71,85,86,123].In
neonates the mortality rates may be as high as 25% and only 22% have an impairment-free survival [86,124].
Survivors of the acute phase of CVT are at increased risk for a set of long-term sequelae, including recurrent sinus
thrombosis, additional venous thrombosis (both intracranial and extracranial), seizure, vision loss, and headaches [66,69].
In the ISCVT follow-up cohort 14.1% reported severe headache (requiring bed rest or hospitalization), 10.6% had seizure,
4.3% had an additional thrombotic event, and 2.2% had recurrent sinus thrombosis [69]. Of note, 41.5% of the patients
who developed recurrent sinus thrombosis or an additional thrombotic event were on anticoagul ation at the time of the
event [69].
Despite the relatively low risk of recurrent CVT, the AHA/American Stroke Association (ASA) guidelines state that
surveillance imaging at 3e6 months in stable patients is reasonable to assess for recanalization of the occluded cortical
vein or sinus [66]. During the acute or subacute phase, if a CVT patient has persistent or evolving symptoms, the AHA/
TABLE 33.3 Multivariate Predictors of Death or Dependence From the ISCVT Trial [69]
Age >37 years (HR 2.0)
Male sex (HR 1.6)
Coma (HR 2.7)
Mental status disorder (HR 2.0)
Hemorrhage on admission CT scan (HR 1.9)
Thrombosis of the deep cerebral venous system (HR 2.9)
Central nervous system infection (HR 3.3)
Cancer (HR 2.9)
CT, computed tomography; HR, hazard ratio.
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