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Radiology
Case
28: Contributed by Dr. Uday Limaye
Other Cases
A 50 - year - old man presented with redness, bulging of the left eye and double vision of 25 days' duration four months after suffering a road traffic accident. On examination of left eye, there was proptosis, mild ptosis, congestion and chemosis . The extra - ocular movements were restricted in all directions with maximum in the left lateral direction and diplopia in the same direction. Pupils were normal in size and reaction. Vision and fundi were normal. There was no palpable thrill or bruit. The rest of neurological examination was normal.
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CT scan showed enlarged left superior ophthalmic
vein and bulky left cavernous sinus.
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MRI
showed a distended bilateral cavernous sinus (left > right) with diffuse enhancement
on contrast T1 images. A provisional diagnosis of a left carotico-cavernous fistula
(CCF) was made. Diagnostic angiography and balloon embolisation were planned in
a single session.
On Digital subtraction
angiography of the left internal carotid angiogram (ICA), there was an impression
of direct left CCF.
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The fistula was draining anteriorly via the superior ophthalmic vein into facial vein and posteriorly through the inferior petrosal sinus into the internal jugular vein. The opposite cavernous sinus was opacified via coronary sinuses. On vertebral artery (VA) angiogram a fistulous communication between left persistent trigeminal artery (PTA) and cavernous sinus was seen
The left external carotid and right internal carotid angiograms showed no abnormality. Balloon embolisation was attempted with a Gold Bal 2 balloon and Magic MABPPE.( Balt Montomereny.France) catheter which was was navigated in left ICA to close the rent. Repeated attempts at balloon Embolization failed; hence, coil embolization was planned. The microcatheter - SL - 10 over Transend 14 microwire( Boston,Natick,USA) was navigated through the rent from ICA. On super-selective angiography, the PTA and the fistulous site were opacified. The microcatheter was then navigated into the vertebrobasilar system and selective cannulation of the PTA was done This was followed by coil embolization with detachable coils (GDC / Saphire coils).
The Gold Bal 2 balloon
was then navigated into the left ICA and the balloon was placed and inflated across
the take off of the PTA in the cavernous ICA A left carotid angiogram at this
time showed excellent cross - flow across the anterior communicating artery with
normal symmetrical venogram. The left ICA was occluded, the PTA and fistula did
not fill. The left ophthalmic artery was seen to be reformed from the left ECA
with some antegrade flow in the left supraclinoid ICA.. The balloon was then detached
and two 0.035" platinum coils were placed in the proximal ICA (Boston ,Natick,USA).
Post embolisation left carotid and vertebral angiograms showed occlusion of the
left ICA, PTA and the fistula. Right carotid angiogram showed excellent opacification
of the left ACA and MCA branches.
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The procedure was uneventful
.Post procedure patient's proptosis / chemosis / congestion disappeared over 48
hrs with improvement in extra-ocular movements and decrease in diplopia . At the
time of discharge, mild left lateral rectus paresis was noted.
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The patient had only streaky hemoptysis for two days after the embolisation and was hemoptysis free for next two days. She was discharged on the fourth post procedure day.
DISCUSSION:
PTA is rare anatomic carotid - basilar
anastomosis seen in 0.1 to 0.3% of cases. It's presence can be confirmed only
on a cerebral angiogram. An increased incidence of intracranial vascular abnormalities
is noted with its presence, the commonest being an aneurysm. Persistent primitive
trigeminal artery appears at the 3mm stage of embryo and by the 20mm stage, it
should disappear. The PTA has a cavernous and an extracavernous segment. It arises
from carotid artery proximal to meningo - hypophyseal trunk and courses in the
cavernous sinus inferior and lateral to the abducent nerve. It then exits from
the posterior part of cavernous sinus by passing lateral to dorsum sella at the
petrous apex or through it to join the basilar artery between the superior cerebellar
and anterior inferior cerebellar arteries.
Saltzman classified PTA - into two types. Type 1: - PTA supplies the Vertebro - basilar system distal to the anastomosis. The basilar artery proximal to the anastomosis is hypoplastic and the posterior communicating artery (PCoA) is often absent. Saltzman Type 2: - Anastomosis supplies the superior cerebellar arteries on both sides , the ipsilateral posterior cerebral artery is through a patent PCoA. Occasional combinations of these two variants are seen
We divide PTA into two types depending on their relevance in supplying the posterior circulation. The dominant and the non-dominant type. The clinical relevance of PTA is debatable - as most of time, the posterior circulation does not depend on it. In our case sacrificing the PTA was not associated with any brain stem ischemia.
Few case reports of PTA cavernous fistula are available in the literature but none from Indian literature. Only two more cases of post traumatic PTA - cavernous fistula with a rent in the cavernous sinus resembling our case were found on reviewing the literature Endovascular obliteration of a PTA - cavernous fistula often involves the PTA sacrifice and in reported cases, both the anterior and posterior approaches have been utilized. Since the fistula was on the intracavernous segment of the PTA and was opacified both on carotid and vertebral angiograms, the PTA had to be sacrificed in our case both downstream and upstream from its intracavernous rent. A posterior approach to the PTA and fistula was used as the longer segment of the PTA allowed more secure catheterization. The fistula was still seen on the ICA angiogram after embolizing the PTA from posterior circulation
However the ICA had to be sacrificed as the course of PTA was very short and the site of rent in its intracavernous segment was extremely close to ICA which lead to an unstable microcatheter position. Hence selective PTA embolisation could not be done.
Carotid - cavernous fistulas are classified by Peteers, Kroggers and Barrows into 4 types .Types one fistula are direct CCF i.e. there is direct communication between the cavernous segment of carotid artery and cavernous sinus. These are the most common types of CCF. Type 2 fistulas are the rarest of all and are on the branches of cavernous segment of ICA. Type 3 fistulas are supplied by branches of external carotid artery and Type 4 fistulas are supplied by braches of ECA and cavernous segment of ICA. Carotid Cavernous fistulas should be treated at the earliest. Anterior drainage into superior ophthalmic vein leads to secondary optic atrophy due to venous congestion and visual loss. Long standing fistulas lead to ocular cranial nerve palsies. Cortical venous reflux is often seen in high flow fistulas which may rupture leading to intracranial hemorrhage
Fourteen cases having persistent trigeminal cavernous fistula have been described in the literature .These fistulas may occur at he site of origin or in the intracavernous segment of PTA. Enomo et al reported the first case of trigeminal cavernous fistula after a rupture of a PTA aneurysm. Guglemi et al reported two cases where PTA aneurysm may have been responsible for the fistula. Mitchel reported one case of trigeminal cavernous fistula with failed balloon embolisation where it was treated with direct surgical approach. Koji Tokunga et al reported a case of PTA - cavernous fistula presented with intracranial hemorrhage which was treated with double catheter technique via transarterial approach through the persistent trigeminal artery.
Endovascular treatment is the primary and preferred form of treatment for trigeminal - cavernous fistulas. It is a minimally invasive technique to treat complex posterior - anterior circulation vascular anomalies. PTA fistulas are extremely rare and difficult to identify. They mimic direct CCF as in our case. However this is a distinct rare type of cavernous fistulas which should be kept in mind as the management may differ significantly.