Cerebral venous thrombosis: causal factors, clinical manifestations and imaging findings S.Alj, M.Ouali Idrissi, N. Cherif El Idrissi El Ganouni, O.Essadki, A.Ousehal Radiology department, Ibn Tofail Hospital, Cadi Ayyad University, Marrakech. NR5

Introduction(1) Cerebral venous thrombosis : a relatively uncommon neurologic disorder. Clinical manifestations :varied but not specific. Imaging, specially the MRI, plays a primary role in the diagnosis.

Introduction(2) The aim of this study is to describe: - the normal venous anatomy, -clinical manifestations -causal factors -imaging finding in cerebral venous thrombosis.

Methods and patients : Retrospective study from 2007 to 2010 Included in the study : Patients with cerebral venous thrombosis Computed tomography (CT) with contrast media administration : performed in 10 patients. All the patients underwent magnetic resonance (MR) imaging : -axial FLAIR and T1 WI -Sagittal T2 WI -Diffusion WI -MR venography sequences.

Results 1-Epidemiological features: Thirty one patients were included in the study. Patients were aged between 16 and 52 years (medium age of 31 years). twenty five patients were women.

Results 1-Epidemiological features: Causal factors were found in 19 patients (61%): Causal factor N (%) Peripartum state10 (32%) Behcet disease 3 (9%) lupus 1 (3%) Other hypercoagulable states 3 (9%) infection 2 (6%)

Results 2-Clinical manifestations : Clinical manifestations included : -Headache :11 patients (35%), -Intracranial hypertension:9 cases (29%) -Seizure: 6 cases (19%) -papillary edema : 5 cases (16%)

Results 3-Imaging features: 3.1- CT: CT performed in 10 patients, suspected the diagnosis in 9 cases (90%). Figure 1: CT axial slices performed before and after contrast media administration. Increased attenuation in the sagittal sinus in unenhanced CT slice. Note the empty delta sign on the contrast enhanced slice.

Results 3.2- MRI: MRI showed focal brain abnormalities in 45%. *Oedematous lesions: (4)13% *Hemorrhagic lesions: (27)87% Figure 2: axial slice T1 WI. Frontoparietal hemorrhage lesion secondary to trasverse sinus thrombosis Figure 3: Bilateral hemorrhagic abnormalities of frontal parenchyma. note the hyperintensity of the sagittal sinus wich is thrombosed.

Figure 4: FLAIR WI and T1 WI axial slices. Oedematous lesion of the brainstaim and right parietal parenchyma related to right transverse sinus thrombosis.

Results 3.2- MRI: Location of the thrombus: Thrombus locationN (%) Transverse sinus6 (19) Superior sagittal sinus5 (16) Straight sinus1 (3) Multiple locations14 (45) Cortical veins5 (16)

Figure 5: Same patient of the figure 3.Flair WI Axial slices and T1 WI sagittal slice show an hyperintensity of the sagittal sinus. The angio MRI shows a filling defect of this sinus.

Figure 6: T1 WI axial slices showing an hypersignal of the sagittal sinus.The angio MRI proved the thrombosis of the sinus.

Figure 7: sagittal slices T1 WI showing an hypersignal of the transverse sinus.The angio MRI shows a filling defect of the left transverse and lateral sinuses and jugular vein.

Figure 8: axial, coronal and sagittal T1 WI with contrast media administration slices. Sagittal and transverse sinuses enhancement after gadolinium administration : Chronic dural sinus thrombosis.

Figure 9: cortical veins occlusion. Hyperintensities cortical and subcortical in frontal and parietal parenchyma on Flair WI.

Discussion Cerebral venous thrombosis is uncommon disorder. Annual incidence is estimated of cases per million in the general population. Accuracy of the cross-sectional imaging methods for detecting abnormalities in the cerebral venous sinuses has been proven. The knowledge of venous sinuses anatomy is necessery to establish the accurate diagnosis. and the knowledge of the causal factors may help in the diagnosis and the choice of the treatment.

Discussion Venous sinuses anatomy (1): Figure 9: lateral view of MR venography, with a color overlay, demonstrates the dural sinuses: -superior sagittal sinus (green), -inferior sagittal sinus (light blue), -straight sinus (dark purple), -confluence of the sinuses (orange), -transverse sinuses (dark blue), -sigmoid sinuses (yellow). - internal jugular veins and bulbs (light purple).

Discussion 1-Causal factors: Many causes of venous thrombosis have been described in the literature Systemic factors : - Related to general clinical conditions -More frequent (18/19 cases in this study) - A peripartum state, and hypercoagulable states (protein S and protein C deficiencies, malingnancies...). Local factors: includes local infections, intracerebral tumor developped near a venous sinus.

Discussion 2-Clinical manifestations: Headache :is the more frequent symptom found in 75-95% of the patients, in this study it was found only in 35% of cases. Intracranial hypertension: occurs in 20%–40% of patients with cerebral venous thrombosis (29% in this study). focal neurologic symptoms : including seizure, are more often seen in patients with parenchymal abnormalities.

Discussion 3-Imaging features: 3.1-Parenchymal abnormalities Parenchymal changes have been identified in 45% of patients: -Focal oedema depected in about 25% of cases in the litterature (12% in this study). -Hemorrhage may coexist in the same region of oedema. in some cases, the parenchymal changes may not correlate with the location of venous occlusion Parenchymal swelling (Sulcal effacement and diminished cistern visibility )without signal abnormalities may occur. Imaging features:

Discussion 3.1-Parenchymal abnormalities: Diffusion abnormalities The value of ADC allows to distinguish between vasogenic and cytotoxic oedema, wich have a prognosis value. Patients with diminished ADC values (cytotoxic oedema) more often have parenchymal sequelae those with normal or increased ADC (vasogenic oedema) usually do not have sequelae. Imaging features:

Discussion 3.2-Sinus abnormalities: Computerized tomography: - unenhanced CT: hyperattenuating thrombus in the occluded sinus - contrast-enhanced imaging : the empty delta sign (a central intraluminal filling defect) Increased attenuation in the venous sinuses in unenhenced CT can also be seen if: -deshydration, -an elevated hematocrit level, -A subarachnoid or subdural hemorrhage. Imaging features:

Discussion 3.2-Sinus abnormalities: MRI: Absence of a flow void with presence of abnormal signal intensity in the sinus Detect a thrombus on MR images, Sinus enhancement after gadolinium administration may be seen in chronic thrombosis. The signal intensity of venous thrombi on T1- and T2- weighted MR images varies in the time (Table 3) Imaging features:

Discussion stageT2 WI signalT1 WI signalT2* Acute: 0-5 days (Desoxyhemoglobin) Iso intenseHypointense Subacute: 6-15 days (Methemoglobin) Hyperintense Hypointense Chronic ≥16 days Hypo/iso/hyper intense Hypointense Imaging features: Table 3: Signal abnormality of the thrombosed sinuses according to the stage of the thrombosis

Conclusion The clinical manifestations of cerebral venous thrombosis vary, depending on the extent and the location, of the venous thrombotic process. Causal factors are essentially systemic with peripartum state being the main cause. MRI plays a primary role in the diagnosis essentially Angio MR. Brain abnormalities are inconstant. Anatomic distribution of thrombosed cerebral venous structures vary.

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