-INTRODUCTION
Cerebral venous thrombosis (CVT) is a rare but potencially fatal cerebrovascular disease,
corresponding for 1-2% of all strokes in adults,
with an anual incidence of 2 to 7 persons per million (4) and a mortality rate of 8% (8).
It can affect all age groups,
although is more common in young patients and characterized by female prominence (8,
12).
The duration time of the cerebral venous thrombosis can be classified in acute (< 48 hours),
subacute (between 48 hours and 30 days) and chronic (more than 30 days).
(5) Usually there are multiple locations of thrombosis (found in as many as 90% of patients),
particularly in the contiguous transverse and sigmoid sinuses.
(8,
9)
-CAUSES AND RISK FACTORS
Although in most of patients with CVT,
at least one prothrombotic risk factor or a direct cause is identified,
usually there are other several coexisting subclinical factors that should also be corrected to prevent its recurrence.
(2) While in as many as 25% of cases,
no cause is identified.
(9)
Genetic prothrombotic conditions
|
Acquire prothrombotic states
|
Infections
|
Inflammatory disease
|
Hematologic conditions
|
Drugs
|
Others
|
Antithrombin deficiency
Protein C and protein S deficiency
Factor V Leiden mutation
Prothrombin mutation
Others
|
Nephrotic syndrome
Antiphospholipid antibodies
Homocysteinemia
Pregnancy
Puerperium
|
Otitis
Mastoiditis
Sinusitis
Meningitis
Systemic infectious disease
|
Systemic lupus erythematosus
Wegener`s granulomatosis
Sarcoidosis
Inflammatory bowel disease
Behcet`s syndrome
|
Polycythemia
Trombocithemia
Leukemia
Anemias (e.g.
sickle cell disease; paroxysmal nocturnal haemoglobinuria)
|
Oral contraceptives
Asparaginase
|
Mechanical causes
Surgery
Trauma
|
Table 1.
Most common causes and risk factors associated with cerebral venous thrombosis.
Figure 1. More common cerebral venous thromobosis etiologic factors according to pacients age.
-ANATOMY
v DURAL VENOUS SINUSES (Figure 2)
· Include superior sagittal sinus,
inferior sagittal sinus,
straigth sinus,
bilateral tranverse sinus,
sigmoyd sinus and cavernous sinus.
· Are enclosed in the leaves of the dura and serve as the major drainage pathway of the cerebral veins.
(9)
· The basal dural sinuses are complex and are interconnected with the cavernous sinus complex.
Multiple emissary channels in the skull base connect with the sigmoid sinus and jugular bulb.
(9)
· The superior sagittal sinus drainage territory comprises the majority of the superior cerebrum.
· The transverse sinuses drain blood from the lateral surfaces of the temporal,
parietal and occipital lobes.
(11)
Figure 2.
Dural venous sinuses. A) MIP image from contrast-enhanced MR venography demonstrates the anterior (a),
medium (m) and posterior (p) segments of superior sagittal sinuses (SSS); inferior sagittal sinus (ISS) and straight sinus (StS).
B) Lateral MIP image from contrast-enhanced MR venography demonstrates the transverse sinuses (TS),
and sigmoid sinuses (SigS) and the internal jugular veins and bulbs (JV).
· SUPERFICIAL VENOUS SYSTEM
· The superficial veins of the cerebrum empty into the dural sinuses and are variable in morphologic structure and location.
(9)
· Superiorly draining (ascending) superficial veins are named for the area of cortex that they drain.
(9)
· Inferiorly draining (descending) superficial veins include the Labbe ́ vein and the sylvian (superficial middle cerebral) veins.
(9)
· The sylvian veins drain the peri-insular region and drain into the basal dural sinuses (sphenoparietal and cavernous sinuses).
(11)
· The vein of Labbe ́,
if dominant,
can comprise much of the transverse sinus drainage territory.
(11)
· DEEP VENOUS SYSTEM
· Includes the straigth sinus,
the vein of Galen,
the internal cerebral veins (ICV) and their tributaries; the basal veins of Rosenthal (BVR) and their tributaries; and the medullary and subependymal veins,
which drain the hemispheric white matter.
(8,
9) The thalamostriate and septal veins coalesce into the internal cerebral veins.
(11)
· Is responsible for drain the inferior frontal lobe; most of the deep white matter of the frontal,
temporal,
and parietal lobes; the corpus callosum; the upper brainstem; the basal ganglia; and the thalamus.
(9)
· Parenchymal alterations typically involve the thalami,
probably because the primary venous pathways that drain the thalami extend directly into the internal cerebral veins.
(9)
· The deep medullary veins,
which are tributaries of the thalamostriate and septal veins,
drain the deep gray structures,
deep white matter and deep central midline cortex.
(9)