Non-contrast-enhanced CT of the brain at presentation (a, b) and after clinical deterioration on the day of the angiography (c, d). (a) This non-contrast CT shows hyperdensity of the vein of Galen and the straight sinus consistent with thrombotic occlusion. Not the normal density of the superior sagittal sinus. There is no abnormality of the brain parenchyma, especially not of the thalami. (b) This CT at a more caudal location shows a hyperdense left sigmoid sinus and a normal right sigmoid. (c) This non-enhanced CT scan before and after the patient became unconscious shows prominent thalamic edema bilaterally. The low-density changes extend into the medial basal ganglia on the left. There is high density of the internal cerebral veins, the vein of Galen, and the straight sinus. (d) This slice shows now a large hyperdense thrombus in the left transverse sinus. As this clot propagation had occurred under intravenous heparin medication, the patient was referred for endovascular treatment with selective thrombolysis and clot aspiration