Wk 1, Case 5 - Review

Patient History
44-year-old male with 3 month history of intermittent pain and redness within the left eye.

Findings
Noncontrast Head CT:

Left-sided proptosis is demonstrated. Asymmetric diffuse thickening of the left-sided extraocular muscles including the superior, lateral, inferior, and medial rectus. There does appear to be a degree of tendinous sparing. The optic nerve is symmetric in size relative to the right. No significant inflammatory stranding within the left orbit. The right orbit is normal.

No evidence of acute infarction. No intracranial hemorrhage. No extra-axial collection. No mass, mass effect, or midline shift. The basal cisterns are patent. Ventricular caliber and configuration is normal.Paranasal sinuses are clear. No mastoid effusion. Bony calvaria and skull base are intact without focal lesion.

CTA Head:

There is asymmetric dilation and early opacification of the left superior ophthalmic vein with enhancement extending to the cavernous sinus such as on series 7 image 129 suspicious for a cavernous carotid fistula. Key images made. There are asymmetric prominent left superficial middle cerebral and middle meningeal veins which are likely outflow drainage. The right supraophthalmic vein is not opacified. There is no CT angiography evidence of a cavernous ICA aneurysm.

The intracranial portions of the internal carotid arteries are patent bilaterally without stenosis. The middle and anterior cerebral arteries are patent bilaterally without a site of stenosis.The left vertebral artery is dominant. Intradural portions of the vertebral arteries are patent bilaterally without stenosis. Vertebral arteries join to form a normal caliber basilar artery. Conventional branching pattern of the basilar artery. Superior cerebellar and posterior cerebral arteries are patent bilaterally without stenosis.No intracranial aneurysm is identified.

Impressions
1. Asymmetric dilation and early opacification of the left superior ophthalmic vein extending to the cavernous sinus suspicious for a cavernous carotid fistula. No CTA evidence of a cavernous carotid aneurysm. Further evaluation with conventional angiography is recommended.

2. Unilateral left proptosis and diffuse enlargement of the extraocular muscles again demonstrated favored to be secondary to suspected cavernous carotid fistula.

3. Patent intracranial circulation with no flow-limiting stenosis. No intracranial aneurysm identified.

Findings
Brain: The signal intensity of the brain shows a few foci of subcortical white matter high signal intensity in the right frontal regions, age-appropriate. There is no evidence of restricted diffusion in the brain to suggest an acute infarction. The post gadolinium enhanced scans also show no evidence of intracranial parenchymal or meningeal enhancement. The mastoid air cells and paranasal sinuses are clear.

Orbits: There is enlargement of the medial rectus muscle, superior rectus muscle, lateral rectus muscle, and inferior rectus muscle on the left side compared with the right. These muscles also show high signal intensity on T2-weighted scanning and diffuse enhancement on the left side. There is no extension to the cavernous sinus. There is no evidence of orbital apex obliteration of fat. The left globe is proptotic. There is increased enhancement of the optic nerve sheath complex on the left side compared with the right. There appears to be an element of tendon sparing nature to the enlargement of the extraocular muscles. There is mild enhancement of the cornea seen best on series 19 image 11. There is faint enhancement of the papilla of the optic nerve on the left side seen best on series 19 image 12. The lacrimal gland on the left side is similar in size to that on the right. The superior ophthalmic vein on the left side is relatively large compared to that on the right.

Impressions
Unremarkable evaluation of the brain.Enlargement and enhancement of the bellies of the extraocular muscles on the left side as well as asymmetric enhancement of the optic nerve sheath on the left and the corneal superficial surface of the globe with associated proptosis. While idiopathic orbital inflammation is favored due to the unilateral nature of the abnormality, one should still consider a cavernous-carotid fistula in the differential diagnosis due to the asymmetry of the left superior ophthalmic vein compared to the right. Consider doppler ultrasound of the orbit to determine flow direction. Also thyroid ophthalmopathy should be considered.

Findings
Cerebral Angiogram: Right common femoral artery: RAO view. Right subclavian artery: AP and lateral views. Right vertebral artery: Townes and lateral views of the head. Right common carotid artery: RAO and lateral views of the neck, AP, lateral, and magnified oblique views of the head left subclavian artery: AP and lateral views of the head left common carotid artery: AP and lateral views of the head left internal carotid artery: LAO and lateral views of the neck, AP and lateral views of the head left external carotid artery: AP, lateral, magnified oblique views of the face.

Impressions
1. Left-sided indirect carotid cavernous fistula (Barrow type D) with arterial supply from the left internal carotid artery via the inferolateral trunk and possibly meningohypophyseal trunk, and from the left external carotid artery via the artery of foramen rotundum.
2. Retrograde filling of the left superior and inferior ophthalmic veins which appear to be occluded/severely narrowed more anteriorly.
3. Prominence of the left vidian artery, which is a nonspecific finding however, the angiographic visualization of which is somewhat unusual in a patient of this age. This finding has been reported to be present in patients with certain head and neck malignancies and therefore correlation with cross-sectional imaging of the head and neck as well as oral examination is recommended.