Acute Distal Internal Carotid Artery Occlusion in Which Angiography during Mechanical Thrombectomy Revealed a Shunt between the Internal Carotid Artery and the Cavernous Sinus: A Case Report

Abstract

Objective: We report a patient with occlusion of the distal internal carotid artery (ICA), in whom angiography during mechanical thrombectomy revealed a shunt between the ICA and the cavernous sinus.

Case presentation: A 79-year-old man with bile duct cancer, a liver abscess, septic shock, and atrial fibrillation presented to our hospital with sudden disturbance of consciousness, conjugate eye deviation, and right hemiplegia. A cranial CT revealed a hyperdense middle cerebral artery (MCA) and loss of gray-white matter differentiation, suggesting large vessel occlusion. Endovascular therapy was immediately initiated. Left internal carotid angiography indicated occlusion of the distal ICA at the origin of the ophthalmic artery. Injection of contrast medium at a site just proximal to the ICA occlusion depicted the cavernous sinus and inferior petrosal sinus. We withdrew the aspiration catheter to the petrous segment of the ICA and injected contrast medium again. This time, however, neither the cavernous sinus nor the inferior petrosal sinus was visualized. We deployed a stent retriever at the occlusion site and successfully removed the thrombus. The final angiography showed complete recanalization of the affected arterial segment with no sign of a carotid cavernous fistula. The patient was finally discharged on day 73 after endovascular therapy with a cerebral infarction in the territory of the left MCA.

Conclusion: In the present case, angiographic visualization of the cavernous sinus varied depending on the site of contrast medium injection. It appears that the high pressure of the contrast medium generated in the stump of the ICA opened up microvascular shunts between the normal capillaries of the ICA and the cavernous sinus, leading to visualization of the cavernous sinus. Therefore, it is important to be aware that injection of contrast medium into the blind alley of the ICA near the cavernous sinus could result in early visualization of the cavernous sinus.

Keywords: cavernous sinus; large vessel occlusion; mechanical thrombectomy.

Fig. 1. CT image at onset shows loss of gray-white differentiation in the left cerebral hemisphere and a hyperdense left MCA. MCA, middle cerebral artery

Fig. 2. Left internal carotid angiography. Initial diagnostic angiography from the balloon guiding catheter ((A) anteroposterior view and (B) lateral view) revealed distal ICA occlusion just distal to the origin of the ophthalmic artery. Injection of contrast medium through the balloon guiding catheter into a site just proximal to the ICA occlusion ((C) anteroposterior view and (D) lateral view) led to visualization of the left cavernous sinus (arrow) and left inferior petrosal sinus (arrowhead). However, the left cavernous sinus and left inferior petrosal sinus could no longer be visualized following injection of contrast medium into the petrous segment of the ICA ((E) lateral view). The final angiogram ((F) anteroposterior view and (G) lateral view) showed complete recanalization of the left ICA and MCA. ICA, internal carotid artery; MCA, middle cerebral artery

Fig. 3. MRI obtained on the day after the endovascular therapy. FLAIR image showing a hyperintense area in the left MCA territory (A). MRA showing maintained recanalization of the left ICA and MCA (B). ICA, internal carotid artery; MCA, middle cerebral artery