Left retrosigmoid approach to the excision of the left cerebellopontine meningioma noted. No definite filling defect in the left transverse or sigmoid sinus.
Appearance on the post-operative scans is more suggestive of a small amount of haemorrhage within the extra-axial space at the surgical site rather than sinus thrombosis. A 3mm filling defect at the confluence of the vein of Galen, the straight sinus and the inferior sagittal sinus probably does represent a small thrombus.
Remaining imaged sinuses, jugular bulbs and imaged internal jugular veins opacify uniformly.
Conclusion: Small (3mm) venous sinus thrombosis.