major cause of the retrograde spread, but studies have since shown that the ophthalmic and facial veins are not valveless. Staphylococcus aureus is the most common infectious microbe, found in 70% of the cases. Streptococcus is the second leading cause. Gram-negative rods and anaerobes may also lead to cavernous sinus thrombosis. Rarely, Aspergillus fumigatus and mucormycosis cause CST. Aseptic cavernous sinus thrombosis is much less common and is usually associated with other disorders including trauma, circulatory problems, nasopharynx cancers and other tumors of the skull base, dehydration, and anemia. Diagnosis The diagnosis of cavernous sinus thrombosis is made clinically, with imaging studies to confirm the clinical impression. Proptosis, ptosis, chemosis, and cranial nerve palsy beginning in one eye and progressing to the other eye establish the diagnosis. Cavernous sinus thrombosis is a clinical diagnosis with laboratory tests and imaging studies confirming the clinical impression. Laboratory tests CBC, ESR, blood cultures and sinus cultures help establish and identify an infectious primary source. Lumbar puncture is necessary to rule out meningitis. Imaging studies Sinus films are helpful in the diagnosis of sphenoid sinusitis. Opacification, sclerosis, and air-fluid levels are typical findings. Contrast-enhanced CT scan may reveal underlying sinusitis, thickening of the superior ophthalmic vein, and irregular filling defects within the cavernous sinus; however, findings may be normal early in the disease course. An MRI using flow parameters and an MR venogram are more sensitive than a CT scan and are the imaging studies of choice to diagnose cavernous sinus thrombosis. Findings may include deformity of the internal carotid artery within the cavernous sinus, and an obvious signal hyperintensity within thrombosed vascular sinuses on all pulse sequences. Cerebral angiography can be performed, but it is invasive and not very sensitive. Orbital venography is difficult to perform, but it is excellent in diagnosing occlusion of the cavernous sinus. Differential diagnosis Orbital cellulitis Internal carotid artery aneurysm Stroke Migraine headache Allergic blepharitis Thyroid exophthalmos Brain tumor Meningitis Mucormycosis Trauma Treatment Recognizing the primary source of infection (i.e., facial cellulitis, middle ear, and sinus infections) and treating the primary source expeditiously is the best way to prevent cavernous sinus thrombosis. Antibiotics Broad-spectrum intravenous antibiotics are used until a definite pathogen is found. Nafcillin 1.5 g IV q4h Cefotaxime 1.5 to 2 g IV q4h Metronidazole 15 mg/kg load followed by 7.5 mg/kg IV q6h Vancomycin may be substituted for nafcillin if significant concern exists for infection