Internal Carotid Thrombosis

Coronal T1 MRI with contrast (on day of admission) showing left cavernous sinus enlargement and thickening.

Axial MRI on day of admission. The MRI demonstrates left cavernous sinus enlargement, decreased caliber of the left internal carotid artery, sphenoid and ethmoid sinusitis, posterior fossa empyema, and suppuration of the left internal auditory canal.
Discussion

Magnetic resonance angiogram (on day of admission) demonstrating stenosis of the distal left internal carotid artery in the region of the cavernous sinus.

Septic cavernous sinus thrombosis (CST) is almost always caused by infections of the middle third of the face and paranasal sinuses. In the pre-antibiotic era, CST was almost universally fatal. The current estimate of mortality is approximately 30%, in part due to delayed diagnosis. 1 Patients who do survive often have residual cranial nerve palsies.
Sphenoid and ethmoid sinusitis are almost always implicated in sinus-related CST. Valveless diploic veins draining the sinuses communicate with the cavernous sinus, allowing spread of infection. The veins are most abundant in adolescents, increasing their risk of intracranial complications of sinusitis. For reasons unknown, males are more likely to develop CST. 2 Infection may also spread through defects in sinus walls. Our patient's imaging was negative for bony fractures.

References
1. Southwick FS, Richardson Jr. EP, Swartz MN. Septic thrombosis of the dural venous sinuses. Medicine. 1986; 65: 82-106. (s)
2. Clayman GL, Adams GL, Paugh DR, Koopmann Jr. CF. Intracranial complications of paranasal sinusitis: A combined institutional review. Laryngoscope. 1991; 101:234-239. (s)