CLINICAL HISTORY:

A 3 year old boy presented with fever, swelling of the right eye and altered sensorium.

MRI BRAIN & ORBIT WERE DONE:

T2 hyper and T1 hypointense fluid intensity signals were seen within the right mastoid air cells and middle ear cavity along with patchy areas of T2 hyperintensity involving the right petrous apex. Foci of restricted diffusion with low ADC values in the right parasellar region and the region of the right cavernous sinus. Subtle foci of T2 and flair hyperintensity around the right ICA cavernous segment with bulging of the lateral wall of the right cavernous sinus

Right orbital proptosis with preseptal edema. The right superior ophthalmic vein was enlarged in size with loss of flow void.

Post contrast images showed a filling defect at the right cavernous sinus region, suggesting a thrombus. Thrombosis of the right superior ophthalmic vein.

DISCUSSION

Cavernous sinus thrombosis can have septic as well as aseptic causes, septic being much more common. It most often occurs as a complication of bacterial or fungal sepsis in the paranasal sinuses, the face, the orbits, and the skull base. More commonly it results from a local spread, often from valveless facial and ophthalmic veins, more severely affecting diabetic and immunocompromised patients. Other causes include cavernous sinus compression by trauma/ tumor and prothrombotic conditions.

Embolization of bacteria can trigger thrombosis that becomes trapped in the cavernous sinus, resulting in cavernous sinus thrombosis from septic etiology. The resulting reduction in venous drainage can result in ptosis, proptosis, painful eye movements, chemosis, periorbital and facial edema, retinal venous distension, and loss of vision.

IMAGING FEATURES

Contrast enhanced studies demonstrate the extent to which imaging helps in the identification of thrombosis via direct visualization of the thrombus or filling defect in the cavernous sinus or by indirect signs that include dilation of the draining tributaries, proptosis, and abnormal dural enhancement.

CT

• In 25% of cases, non-contrast CT shows high density thrombus in the affected cavernous sinus
• Distended cavernous sinus with a non-fat density filing defect was seen in contrast-enhanced CTs
• The scan also showed the presence of mass lesions near the sphenoid or pituitary gland (sinusitis/mastoiditis). This could be a sign of an underlying cavernous sinus pathology.

MRI

• Absent flow void
• Signal characteristics vary depending on the age of the thrombus
• Absence of enhancement on contrast images
• MR venography

COMPLICATIONS

As the dural venous and cavernous systems are valveless, communication between dural sinuses and cerebral and emissary veins can lead to meningitis, dural empyema or cerebral abscess. Propagation of infection via the internal jugular vein can result in septic pulmonary emboli, pulmonary abscess, pneumonia or empyema. Compression of the internal carotid artery and pituitary gland may result in stroke and hypopituitarism respectively.

Dr. Shabna Jasmin K
Radiologist