Cerebral Venous Thrombosis Self-Assessment Module

1. DR NIJALINGAPPA
NAIR HOSPITAL
MUMBAI

2. QUESTION 1
Which of the following statements regarding
etiologic factors of cerebral venous
thrombosis
(CVT) is TRUE?
A. In adults, the most important cause is
infection.
B. When CVT is associated with pregnancy
and puerperium, the risk is highest during
the third trimester.
C. Increasing age is a risk factor.
D. In a large proportion of cases, the causes
cannot be identified.

4. Solution to Question 1
Infection contributes to fewer than 10% of cerebral
venous thrombosis (CVT) cases in adults. Option A is not
the best response. CVT occurs more often in puerperium
than during the pregnancy. Option B is not the best
response.
Although pregnancy-related CVT occurs more often
in older women, aging per se is not a risk factor. Option
C is not the best response. In 20–35% of cases, the cause
remains unknown, so one should remain suspicious even
in the absence of known risk factors. Option D is the
best response. The pathogenesis of CVT is complex and
is poorly understood.

5. QUESTION 2
All of the following are clinical
presentations
closely associated with CVT EXCEPT:
A. Chronic headache.
B. Altered mental status.
C. Subdural hemorrhage.
D. Focal neurologic deficits.

7. Solution to Question 2
Common presentations include headache, focal neurologic
deficits, seizures, and altered consciousness. Options A, B,
and D are not the best responses. A syndrome of intracranial
hypertension (headache and papilledema) accounts for 40% of
cases in a series, so CVT needs to be excluded in patients
considered for the diagnosis of benign intracranial
hypertension.
Although subdural hemorrhage has not been associated
with CVT, cases of subarachnoid hemorrhage as a rare
presentation of CVT have been reported. Option C is
the best response. There is also a wide distribution in the
mode of onset of symptoms, with approximately 28% acute
(< 48 hours), 42% subacute (between 48 hours and 30 days),
and 30% chronic (> 30 days) presentation [1]. Option A,
which is true, is not the best response. The teaching point is
that CVT may present with an atypical presentation or even
an absence of clinical symptoms.

9. QUESTION 3
Direct and indirect signs of CVT on CT include
all of the following EXCEPT:
A. Hemorrhagic cerebral infarction sparing the
cortex, but involving the subcortical region.
B. The empty delta sign on unenhanced CT.
C. Enhancement of the falx and tentorium on
contrast enhanced CT.
D. A “dense clot sign” on unenhanced CT.

11. Solution to Question 3
An infarction not conforming to a major arterial vascular
territory, such as the presence of multiple isolated lesions, involvement
of the subcortical region with sparing of the cortex,
or extension over more than one arterial distribution, is highly suspicious for
a venous cause. The infarction may be
hemorrhagic or nonhemorrhagic. Option A is not the best response.
The empty delta sign may be seen on contrast-enhanced
CT and represents a filling defect (thrombus) in the dural sinus,
with peripheral enhancement possibly secondary to the development
of collaterals. The empty delta sign may be seen 5
days to 2 months from onset . Option B is the best response.
Indirect evidence of CVT may be seen as contrast enhancement
of the falx and tentorium, secondary to venous stasis
and hyperemia of the dura mater. This is seen in approximately
20% of cases. Option C is not the best response. The “dense
clot sign” and the dense cord sign represent direct visualization
of the thrombosed cortical vein or the venous sinus in short
and long axes, respectively, but are seen in only one third of
cases. Option D is not the best response.

12. QUESTION 4
MRI of a young woman shows swelling and
T2 prolongation of the bilateral thalami and basal
ganglia, consistent with infarction. Which of the
following venous structures is probably thrombosed?
A. Superior sagittal sinus.
B. Inferior sagittal sinus.
C. Labbé’s vein.
D. Internal cerebral vein.

14. Solution to Question 4
An infarction not conforming to a major arterial vascular
territory strongly suggests CVT. The location of an infarction
with respect to the expected course of venous drainage
may provide a clue to the venous structure involved.
Thrombosis in the sagittal sinus often leads to impaired venous
drainage and, therefore, parenchymal change in the
parasagittal region. Options A & B are not the best responses.
Thrombosis in Labbé’s vein should lead to infarction
in the temporal lobe. Option C is not the best response.
Bilateral or unilateral infarction in the thalami, basal ganglia,
and internal capsule is typically seen in deep venous
thrombosis. Option D is the best response.

15. QUESTION 5
On conventional MRI, all of the following are
direct signs of CVT involving the sagittal sinus
EXCEPT:
A. Bright signal in the sinus on T1-weighted
images.
B. Isointense signal in the sinus on T1-weighted
images.
C. Absence of signal in the sinus on FLAIR images.
D. Exaggerated signal loss in the sinus due to
increased susceptibility effect on T2-weighted
gradient-echo images.

17. Solution to Question 5
Venous thrombus may be directly visualized on MRI . On
conventional MRI sequences, patent dural sinuses are often
seen as flow voids; thus, the absence of signal in the dural sinuses
is an indication that CVT is absent. Option C is the best
response because it is not a sign of CVT. The thrombus may
manifest as absence of a flow void, which is often best seen on
FLAIR and T2-weighted spin-echo images. The abnormal signal
intensity follows the signal characteristics of intracranial
hemorrhage and may evolve through the stages of oxyhemoglobin,
deoxyhemoglobin, methemoglobin, and hemosiderin . On T1weighted
images, thrombus with methemoglobin is seen as hyperintensity
replacing the normal flow void. Option
A is not the best response. Thrombus with deoxyhemoglobin is
seen as an isointense or slightly hypointense signal replacing
the normal flow void. Option B is not the best response. On
T2*-weighted gradient-echo images, exaggerated signal loss
(very hypointense) is often seen as a result of the increased
susceptibility effect of deoxyhemoglobin, methemoglobin, or
hemosiderin. Option D is not the best response

18. QUESTION 6
Possible pitfalls in the imaging diagnosis of CVT
include all of the following EXCEPT:
A. Hyperdense blood in newborns on unenhanced CT.
B. Subarachnoid hemorrhage.
C. Arachnoid granulations (pacchionian granulations).
D. Cord sign on unenhanced CT.
E. Hypoplastic dural sinus.

20. Solution to Question 6:
The cord sign represents direct visualization
of a thrombosed cortical vein, seen as linear
hyperdensity, and is therefore not a pitfall in
diagnosis. Option D is the best response