Monday, 22 August 2011

Deep Cerebral Venous Thrombosis MRI

A 36 y o female with 5 days history of headache and vomiting. Now unconscious.
MRI Brain with MR Venogram show:
Abnormal T2 hyper intensity involving thalami, left caudate , callso septal groove with marked focal parenchymal swelling is a venous infarct secondary to deep cerebral venous thrombosis.
Thrombosed internal cerebral veins, vein of Galen and straight sinus seen as serpigenous low signals on T2*GRE images.
Thrombosed straight sinus show loss of normal T2 flow voids, not visualised on MR Venogram, an area of normal expected straight sinus marked with a thin black circle which is devoid of straight sinus. Rest of the dural venous sinuses show normal flow related signals. 


Syn : Internal cerebral vein (lCV) thrombosis.

Cerebral venous thrombosis represents 1% of strokes.
ICV thrombosis = 10% of venous stroke.
Anatomy : Deep cerebral veins consist of two internal cerebral veins join to form vein of Galen which continues as straight sinus.

Imaging wise diagnostic clue is demonstration of clot in internal cerebral veins, vein of Galen, straight sinus, basal veins of Rosenthal – hyper dense on non contrast CT, hyper intense on FLAIR and hypo intense on T2*GRE MRI,
Bilateral ICV thrombosis more common than unilateral.
An associated parenchymal abnormality is involvement of deep gray nuclei, internal capsule, medullary WM typically affected due to venous ischemia or may be the only finding on cross sectional imaging.
Variable involvement of midbrain, upper  cerebellum.
Hypo density with focal parenchymal swelling on non contrast CT in early stages. Hemorrhage hyper dense on CT. T2 hyper intense with focal parenchymal swelling on MRI, may show restricted diffusion on Dw images. Low signal intensity due to hemorrhage on T2*GRE in late and advanced cases.
MR venogram often shows non visualization of straight sinus due to lack of flow related signals secondary to thrombosis.

Associated abnormalities may be thrombosed dural cerebral vein thrombosis. May have thrombosis elsewhere, DVT in lower extremity and pulmonary embolism in Thorax.

Staging, Grading or Classification Criteria for Venous ischemia on imaging
Type 1: No abnormality
Type 2: High signal on T2WI/FLAIR; no enhancement
Type 3: High signal on T2WI/FLAIR; enhancement present
Type 4: Hemorrhage or venous infarction.

DDs of bilateral abnormalities involving thalami, basal Ganglia are Glioma, toxic/metabolic disorders like Carbon monoxide poisoning, Global hypoxia, Arterial infarct possible with tip of basilar occlusion, artery of Percheron occlusion, Encephalitis.
Encephalitis and thalamic arterial infarcts are the closest differentials.
Encephalitis – needs demonstration of normal MR Venogram particularly normal straight sinus.
Thalamic ischemic infarct – needs MR Angiogram which may show abnormal posterior circulation.

Clinical Presentation
Headache is most common. An associated nausea, vomiting, neurologic deficit, seizure.
Affect any age group, although elderly or debilitated patients are more likely to have spontaneous thrombosis. More common in females.

Natural History & Prognosis
Outcome is extremely variable, from asymptomatic to death.
Hemorrhage on GRE, Ischemic changes with restricted diffusion on DWi are associated with poor outcome.

Heparin +/- rTPA.
Endovascular thrombolysis if available.

Reference : Osborn Diagnostic Imaging.

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