Venous and Dural Sinus Thrombus

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       Occlusion of the venous sinuses results in cerebral venous engorgement, brain swelling, and increased intracranial pressure. If the thrombosis extends retrograde and involves the cortical veins, secondary cerebral infarction can occur.

      Acute thrombus is hyperdense on CT and may be detected within one of the major sinuses or cortical veins. The other classic sign is the "empty delta" sign due to nonfilling of the superior sagittal sinus on a contrast scan. Nonetheless, MR is far superior for diagnosing abnormalities of the cerebral veins and sinuses. Normally, the dural sinuses have sufficient flow to exhibit a flow void. If that flow void is missing or if the sinuses are hyperintense, thrombosis should be suspected. One must be careful to exclude the possibility of any in-flow enhancement effect. The diagnosis must be confirmed with gradient-echo techniques or MR angiography. Phase-contrast MRA is the preferred technique because it is not adversely affected by intraluminal clot. Endnote

      Associated parenchymal infarcts are found in the areas of venous abnormalities, and the infarcts are often hemorrhagic because arterial perfusion is maintained to the damaged tissue. In cases of superior sagittal sinus thrombosis, the infarcts are typically bilateral and in a parasagittal location. 

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