King Edward Memorial Hospital - Departments: Radiology

A 50- year- old man had trauma to the right side of the head in a vehicular. Accident. Following the injury, he had double vision when he looked to the right side. After a period of two months, he started having redness of the right eye. This gradually increased. He then started hearing swishing sounds in the right ear since one month.

On examination, there was redness with conjunctival congestion (Fig 1). The external ocular movements were full. The fundus was congested and the vision was normal. A bruit was heard on the right eye.

Fig 1

An MRI of the brain and orbits (Fig 2,3) showed a dilated right superior ophthalmic vein and both the cavernous sinuses were prominent. MR venogram (Fig 3 )showed multiple vascular channels near the cavernous sinuses which appeared to be prominent .

Fig 2

Fig 3

The digital subtraction angiogram (Fig 4A,4B) showed type A carotico-cavernous fistula (CCF) in the C3 segment of the right carotid artery. The venous drainage of the fistula was anteriorly - into the superior ophthalmic vein and posteriorly into the petrosal sinus and also into the contralateral cavernous sinus. There was distal antegrade flow in the ICA.

Fig 4A

Fig 4B

Transarterial balloon embolisation of the CCF was performed using a #16 Nycomed detachable gold valve balloon. The balloon was navigated across the rent in the artery on to the venous side and inflated to occluded the rent in the artery and thus obliterate the fistula. Once the fistula was occluded by the balloon it was detached.

Post embolisation angiogram (Fig 5A,5B,5C) showed the CCF to be completely obliterated and there was good antegrade flow in the ICA.

Fig 5A

Fig 5B

Fig 5C

Immediately, the bruit in the eye disappeared and the congestion also reduced. The follow up after two months (Fig 6) showed the complete clearing of all symptoms.

Fig 6

Discussion:

Interventional radiological treatment of CCF is a classic example where percutaneous techniques cure conditions which are difficult or impossible to treat by open surgery.

A CCF is one of the commonest fistulas in the craniofacial region. Mostly they are of traumatic etiology occurring secondary to laceration of the internal carotid Artery in the cavernous sinus or rupture of its intracavernous branches. They can also occur due to spontaneous rupture of a intracavernous ICA aneurysm.

The cavernous portion of the internal carotid artery is fixed to the dura at the entry point at the petrous opening into the sinus and exit at the anterior clinoid process. At the time of the injury, the artery is hence exposed to shearing forces leading to laceration and rupture. This leads to an arteriovenous fistula.

The venous drainage from the cavernous sinus is altered and hence depending on the direction of the venous drainage are the manifestation of the signs and symptoms.

Mostly the clinical presentation is due to anterior drainage into the superior ophthalmic vein leading to problems affecting the orbit. When it drains posteriorly into the petrosal system problems relate to of foreign sounds in the ear and cranial nerve involvement of 3^rd,4^th,6^th and 5^th V₁ cranial nerve. When the drainage is into the contralateral sinus it may present as bilateral orbital symptoms. Commonly, there is mixed drainage and predominance of one of the type leading to presenting symptom. There is associated bruit due to high flow in the lesion. There may be cranial nerve involvement mostly of the 3^rd 4^th 5^th and 6^th nerves as they course in the cavernous sinus. Visual loss may be due to the trauma or because of the fistula. This is one of the indication for the emergency treatment of the lesion.

Other symptoms may be the corneal ulcerations, infections secondary glaucoma and diplopia.

TYPE A Intracavernous ICA and cavernous sinus

TYPE B Dural ICA branches and cavernous sinus

TYPE C Dural ECA branches and cavernous sinus

TYPE D Type B and Type C together.

Most of the patients are already evaluated with CT for the orbit and the brain. This shows exopthalmos, prominent SOV and bulging cavernous sinus which is also shows marked enhancement.

For planning the treatment it is necessary to know :

The location and the type of the fistula.
The distal antegrade flow in the ICA and the circulation of the brain including the collateral and cross flow circulation across communicating arteries.
The external carotid circulation.
The course of the carotid arteries and arterial access to the fistula.
The venous drainage of the fistula and the cortical venous drainage and access to the fistula through the venous approach.

Endovascular approach is proffered for treatment of the CCF.

Arterial route of embolisation is preferred using detachable balloons. The detachable balloon is navigated across the fistula onto the venous side and inflated in the cavernous sinus to occlude the rent in the artery thus sealing off the fistula. If it is not possible to get across the rent in the ICA, the balloon is inflated across the rent and the cross flow across the communicating arteries in the brain is observed and the test occlusion is carried out to occlude the parent artery. Microcatheters and coils have also been used to go across the rent onto the venous side and deploy detachable coils to treat the fistula.

Whenever there is better venous access the venous approach to the fistula is performed. This procedure is technically more demanding and chances of transient neuropathies are higher.

Post embolisation care is bed rest for 24 hours; headache and pain management with analgesics. The patient is usually discharged at 48 hours post procedure. Except neuropathies, which may take several weeks to resolve; all other symptoms and signs resolve immediately on occlusion of the fistula.