A 60-year-old woman who is otherwise healthy who presented with progressive right-sided pulsatile tinnitus for 4-6 weeks. She underwent extensive evaluation by her PCP and ENT which included multiple courses of steroids and subsequent advanced MRI and MRA imaging. Several days prior to presentation, she developed new onset diplopia which was found to be secondary to a partial right VI nerve palsy. MRI demonstrates abnormal flow voids in the right Cavernous Sinus, which also enhances densely (Figure 1).
Fig1. A) Axial T2 MRI demonstrates abnormal flow voids in the right Cavernous Sinus; B) Which densely enhances one post Contrast Sagittal (red circles)
We performed a diagnostic cerebral angiogram which confirm the presence of a high flow direct fistula of the right internal carotid artery–right cavernous sinus. Collateral venous drainage into the orbit and skull base was observed (Figures 2 and 3).
Fig 2. A) AP and (B) Lateral DSA Angiogram demonstrate Arterial Venous Fistula of Carotid Cavernous Sinus With Arterialized Flow (Red Arrows) into the Superior Orbital Vein (SOV) and Clival Plexus (Blue Arrows)
Fig 3. Graphic Representation of a Direct Carotid -Cavernous Fistula and Venous Drainage
We decided to proceed with an endovascular approach which required identifying the direct site of the fistula. Secondary to the high flow nature of the fistula, and the presence of a small intra-cavernous aneurysm, we performed an Alcock’s maneuver where the vertebral artery was injected during compression of the Right Carotid Artery to reverse flow and identify the fistula site. In this patient, the incidental superior cavernous aneurysm was unruptured, and the site of the fistula was identified more proximally in the location of a potentially ruptured Otic Artery aneurysm. (Figures 4 and 5).
Fig 4. A) Right ICA Compression with Vert Injection (Alcock’s Maneuver, blue arrow) demonstrate fistula below small Unruptured cavernous aneurysm (green arrow)
Fig 5. Persistent Anastomotic Variants of the ICA and Vertebral Basilar Circulations
We then proceeded to successfully cannulate the direct aperture between the right carotid artery and the cavernous sinus and with the use of a balloon assist technique coil embolized the posterolateral compartment until the fistula was closed and shunting ceased (Figures 6 and 7).
Fig 6. Balloon Assisted Navigation and Embolization of Otic Artery Aneurysm ruptures site into Cavernous Sinus
Fig 7. A and B) AP and LAT DSA confirm complete obliteration of the CFF Arterio-Venous Fistula Site
She experienced immediate cessation of her pulsatile tinnitus with early improvement of the right VI nerve palsy and near complete recovery within 4-6 weeks (diplopia only on far lateral gaze) and permanent cure at 6 months.
Carotid-cavernous sinus fistulae (CCF) occur because of traumatic or spontaneous communication in the walls of the intra-cavernous internal carotid artery or its branches directly to the cavernous sinus resulting in short-circuiting or shunting of high-pressure arterial blood into the venous system of the cavernous sinuses. Intra-cavernous cerebral aneurysms are often felt to predispose to a Direct Carotid-Cavernous Sinus Fistulae, which represent the majority of fistulae in most series. These fistulae usually have high rates of arterial blood flow and most commonly are caused by a single tear or aperture in the arterial wall and can result in rapid progression of clinical symptoms including cranial nerve injuryand vision loss1.
The most used classification, based on angio-architecture, was established by Barrow et al. dividing CCFs into 4 types based on the arterial supply2
Indirect or Dural carotid-cavernous sinus fistulae are characterized by a communication between one or more meningeal branches of the internal carotid artery and/or the external carotid artery with the cavernous sinus. These fistulae usually have lower rates of arterial blood flow initially but may progress to develop higher pressure and cortical venous reflux and associated risks of visual deficits and hemorrhagic strokes3. These lesions may represent congenital or acquired arteriovenous malformations, which develop spontaneously or in association with atherosclerosis, systemic hypertension, collagen vascular disease, cavernous sinus thrombosis, and peri-partum situations in women.
Early evaluation by a neurovascular specialist is recommended for patients presenting with new onset or progressive pulsatile tinnitus, especially in patients with associated visual symptoms (chemosis, proptosis, diplopia) and can often lead to successful treatment and prevention of serious life-threatening complications of the disease.
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