An adult diabetic man presented with sudden right facial swelling, proptosis and complete ophthalmoplegia. He had undergone upper tooth extraction on same side four days previously. Contrast enhanced MRI shows the following changes on right side:
2-Periorbital inflammation (edematous enhanced skin and subcutaneous tissues).
4-Meningeal enhancement consistent with meningitis (White arrow on axial).
5-Enhancing pterygoid muscles consistent with masticator space infection (curved arrow on coronal).
6-Swollen non-enhancing cavernous sinus = cavernous sinus thrombosis (open arrows).
7-Narrowed internal carotid artery (green arrows).

Cavernous sinus thrombosis most commonly results from contiguous spread of infection from the sinuses or middle third of the face, or less commonly dental abscess or orbital cellulitis. Staphylococcus aureus is the most common infectious microbe, found in 50% to 60% of the cases. CST is a clinical diagnosis, however MRI with contrast is the modality of choice to confirm its presence and to differentiate it from alternatives e.g. orbital cellulitis, which may have a similar clinical presentation.

1. Wikipedia
2. Emedicine 2006

Credit: Dr Ahmed Haroun