Endovascular management of carotid cavernous fistula. Important for Neuroradiologists and Neurointerventionalists.

1. Interventional Neuroradiology
Endovascular
Management of Carotid-
Cavernous Fistula
Mohamed M.A. Zaitoun, MD
Interventional Radiology Consultant, Zagazig University Hospitals, Egypt
FINR-Switzerland
zaitoun82@gmail.com
Interventional Radiology Unit,
Zagazig University, Egypt

3. Knowing as much as possible
about your enemy precedes
successful battle and learning
about the disease process
precedes successful
management.

4. Endovascular Management of
Carotid-Cavernous Fistula
a) Definition
b) Etiology
c) Anatomy of the Cavernous Sinus
d) Clinical Picture
e) Imaging Diagnosis
f) Treatment

5. a) Definition :
-A carotid cavernous fistula (CCF) consists of an
abnormal connection between the cavernous
segment of the internal carotid artery (ICA) and
the cavernous sinus
-The resulting high-flow shunt raises pressure in
the drainage pathways of the cavernous sinuses
and causes symptoms due to venous
hypertension in the orbit , cortical or deep
cerebral veins and venous stenosis due to
secondary hyperplasia

6. -It is the most frequent location of direct
intracranial arteriovenous fistulas and the
majority are caused by trauma
-Spontaneous fistulas are caused by rupture of an
aneurysm of the cavernous ICA or other arterial
diseases that weakens the wall
-The connection is usually a single hole or less
frequently a small number of individual holes
-The point of rupture in the arterial wall is often
large (1-10 mm) and spontaneous cure is
therefore rare

7. b) Etiology :
-CCFs are :
1-Traumatic (80%) or
2-Spontaneous (20%)

8. 1-Traumatic (80%) :
a) Accidental blunt trauma due to motor vehicle
accidents (MVA) with direct deceleration injury to
the face and cranium is the commonest history
followed by falling from ladders , buildings ,
horses etc.
b) Arterial injury may occur due to penetrating
injury , gunshot and other missile wounds
c) Iatrogenic trauma : Iatrogenic injuries to the ICA
can occur during trans-sphenoidal
hypophysectomy , paranasal and other types of
intracranial surgery , endovascular treatment
involving angioplasty or Fogarty catheters for
endarterectomy has in the distant past been
blamed for causing arterial injury and fistulas

9. -The passage of the ICA through the skull base
creates bends with fixed sections below the
cavernous sinus where it runs through its canal
in the petrous bone and foramen lacerum , and
above at the dural ring where it is tightly
adherent to dura
-Though held within the arachnoid reflections and
dura of the cavernous sinus , this ICA section is
less supported and particularly prone to injury
following craniofacial deceleration trauma

10. -It is also vulnerable to trauma causing fractures
(e.g. facial bones , skull base) or penetration
wounds
-The mechanism of arterial wall injury is thus either
direct traumatic penetration , tearing of the wall
or avulsion of branch arteries
-If the injured patient is comatose , the diagnosis of
CCF may be delayed because objective signs
take time to become evident or because they are
initially attributed to direct traumatic soft tissue
damage
-Furthermore , the onset of the fistula may not
necessarily occur at the time of trauma , since a
traumatic pseudoaneurysm of the ICA may be
caused which later ruptures to cause a delayed
fistula

11. 2-Spontaneous (20%) :
-The fistula is caused by breakdown in the wall of
a diseased ICA
-The arterial diseases that may be responsible are:
1-Intracavernous Aneurysm
2-Ehler’s-Danlos Syndrome
3-Pseudoxanthoma Elasticum
4-Fibromuscular Dysplasia

12. 1-Intracavernous Aneurysm :
-The presumed cause is usually atherosclerosis
because spontaneous CCF is a disease of older
women
2-Ehler’s-Danlos Syndrome :
-CCF is the most common intracranial
complication of this autosomal dominant
abnormality of collagen metabolism
-It is associated with defects in arterial media and
bleeding due to increased vessel fragility
-Affected people may develop intracranial
aneurysms , and CCFs may be due to rupture of
an intracavernous aneurysm , but when it occurs
, a section of arterial wall is affected in a series
of fistulas , consistent with a diseased (and
weaken) arterial wall

13. 3-Pseudoxanthoma Elasticum :
-Autosomal recessive and dominant forms cause
disruption of elastic fibres in skin , arteries and
eye
-It is a rare cause of G1 bleeding and CCFs
4-Fibromuscular Dysplasia :
-CCF ha also been reported in this condition but it
must be rare, and there have been no recent
similar reports so the association is dubious

14. c) Anatomy of the Cavernous Sinus :
-The cavernous sinus lies lateral to the pituitary
gland and the body of the sphenoid bone
-It extends from the superior orbital fissure to the
apex of the petrous temporal bone
-It is honeycombed by numerous fibrous strands
and traversed by the cavernous portion of the
ICA
-The lateral wall is thicker than the medial wall
(which separates it from the pituitary gland) and
is formed by a double layer of dura

15. -The oculomotor cranial nerves (IIIrd , IVth
and VIth) run within the layers of the
lateral wall
-Anteriorly it receives the superior and
inferior ophthalmic veins , cerebral (uncal)
veins and the sphenoparietal sinus
-It communicates with the opposite
cavernous sinus via a series of anterior
and posterior intercavernous sinuses

17. -The normal outflow is to :
1-The superior and inferior petrosal sinuses
2-The pterygomaxillary venous plexus via
emissary veins
3-The contralateral cavernous sinus
4-And , depending on head position, to the
superior and inferior ophthalmic veins
-The VIth cranial nerve lies closest to the
ICA within the inferior portion of the sinus

18. Patient with a cavernous carotid fistula of the left side after ICA injection , on
the left side contrast is seen in orbital veins ( white arrows ) and in the
pterygoid plexus ( short arrows) , the intercavernous sinus drains to the right
cavernous sinus and then to the inferior petrosal sinus (arrowheads)

19. d) Clinical Picture :
-The commonest presentation is with visual
dysfunction and orbital congestion because the
fistula flows to the orbital veins
-Occasionally, if the superior ophthalmic vein
(SOV) is absent or thrombosed , orbital signs
may be absent or alternatively occur in the
contralateral eye when venous flow is directed
through intracavernous anastomotic connections

20. -Less often , decompression occurs :
1-Posteriorly (via the inferior petrosal sinus)
2-Laterally (via the superior petrosal sinus)
3-Inferiorly (via emissary veins of the foramen rotundum
and foramen ovale to the pterygoid plexus)
4-Superiorly (via the sphenoparietal sinus)
-It is unusual for leptomeningeal and cortical veins to be
involved but since the cavernous sinus connects to the
sphenoparietal sinus , uncal veins and the petrosal
sinuses , raised venous pressure may occur in either the
superficial or deep cerebral venous systems

21. -Common symptoms at presentation are :
1-Bruit
2-Visual Disturbance & Diplopia
3-Cranial Nerve Palsies
4-Epistaxis
5-Cerebral Dysfunction
6-Spontaneous Intracranial Hemorrhage

22. 1-Bruit :
-An almost constant complaint in the conscious
patient is bruit , which may be heard on
auscultation
-The site at which it is loudest gives a clue to the
direction of blood flow from the cavernous sinus
-Thus if the bruit is loudest over the orbit , flow is
anterior and if loudest over the mastoid bone ,
flow is predominantly posterior
-Other causes of similar objective bruit are dural
arteriovenous fistula , absence or hypoplasia of
the sphenoid wing and transmitted sound from
carotid stenosis

23. 2-Visual Disturbance & Diplopia :
-Visual loss caused by damage to the optic nerve
at the time of trauma should be distinguished
from secondary visual disturbance due to CCF
-Permanent post-traumatic monocular blindness is
caused by irreparable damage to the IInd cranial
nerve , otherwise , visual acuity is rarely
severely affected by CCF alone
-The signs are an afferent papillary defect , mild
constriction of the visual fields and rarely central
scotoma

24. -The mechanism is probably a combination of
compression by the enlarged SOV and ischemia
due to the reduced arteriovenous gradient
-Venous hypertension within the orbital veins
causes functional changes that lead to
symptoms
-Most serious is secondary glaucoma caused by
reduced drainage of aqueous humour and a rise
in intraocular pressure (IOP)

25. -Orbital venous congestion causes :
1-Raised IOP
2-Venous retinopathy
3-Proptosis
4-Chemosis , edema of lids and dilated conjunctival
vessels
5-Ophthalmoplegia
-Unilateral fistulas may cause bilateral orbital congestion
(about 20% of cases) , localisation to the side of the
fistula is usually obvious by asymmetry of proptosis or
bruit (unless the SOV is thrombosed) , only 1% of
traumatic fistulas are bilateral

26. 3-Cranial Nerve Palsies :
-Damage to the orbital cranial nerves at the time of
trauma can be distinguished from secondary
palsies by the history and initial findings on
examination
-Early complete cranial nerve palsy has a poor
prognosis and is usually caused by direct
trauma
The cranial nerves of the cavernous sinus are
commonly affected

27. -Isolated IIIth or VIth and combined IIIth + IVth +
VIth cranial nerve palsies are common
-An isolated IVth palsy is said never to occur and
palsies of V1 and V2 are seen but less often
-Muscle weakness due to palsy of the trigeminal
motor division is never caused by CCF alone
-The mechanism of palsies affecting the cavernous
cranial nerves is thought to be due to
interference with their blood supply in the sinus
either by a steal effect or compression of their
vasa nervorum by the enlarged sinus

28. 4-Epistaxis :
-This is usually associated with traumatic CCF and
is attributed to acute vessel damage which may
or may not progress to cause a CCF
-The mechanisms are usually difficult to
demonstrate but may be rupture of a
pseudoaneurysm into the sphenoid or ethmoid
sinuses or secondary to venous hypertension
and engorgement in the pterygoid plexus

29. 5-Cerebral Dysfunction :
-Cerebral ischemia or infarction occurs if the CCF
reduces perfusion to the hemisphere
-This is seen at angiography when all contrast
injected in the ICA flows to the cavernous sinus ,
and the middle cerebral artery territory depends
on collateral blood flow
-Symptoms of cerebral ischemia or infarction occur
if the collateral support is inadequate
-Venous back pressure may affect the brain stem
due to reflux to the basal vein of Rosenthal or
petrosal veins

30. 6-Spontaneous Intracranial Hemorrhage :
-Intracerebral hemorrhage is caused by
raised venous pressure within
subarachnoid or cortical veins
-Drainage to the sphenoparietal sinus may
cause cortical venous hypertension in the
Sylvian veins and very rarely hemorrhage
when other routes are obstructed
-Partial embolisation with closure of other
drainage routes may theoretically cause or
exacerbate cortical venous hypertension

31. e) Imaging Diagnosis :
1-Orbital Ultrasound
2-CT & CTA
3-MRI
4-Cerebral Angiography

32. 1-Orbital Ultrasound :
-This may show a dilated superior orbital vein (SOV) and
disc swelling suggesting the diagnosis
2-CT & CTA :
-Is useful for demonstrating the extent of injury after trauma
-It will demonstrate fractures around the orbit , paranasal
sinuses , skull base and intra- or extra-axial hematomas
or small cerebral contusions
-Proptosis
-A dilated SOV is usually well demonstrated after contrast
enhancement , and the ipsilateral cavernous sinus may
be enlarged
-Orbital edema

33. Axial CT (a) and MRI (b) of a patient with left side proptosis due to
enlarged orbital veins and soft tissue swelling , the T2 shows an
aneurysm in the left cavernous sinus , the fistula is the result of its
rupture

34. 3-MRI & MRA :
-Findings of CCFs include a dilated CS with multiple signal intensity
void structures that are associated with proptosis and an
enlarged superior ophthalmic vein
-Is generally no better than CT but is the best modality for
follow-up imaging after treatment but MRA with high-
frequency imaging may be useful
4-Cerebral Angiography :
-Is required to evaluate the fistula prior to endovascular
treatment
-Rapid shunting from ICA to CS
-Enlarged draining veins
-Retrograde flow from CS , most commonly into the ophthalmic
veins

35. Lateral ICA DSA showing a cavernous carotid fistula draining to an
enlarged superior ophthalmic vein (white arrow) to pterygoid veins
via the inferior ophthalmic vein (single short arrows) , to the inferior
petrosal sinuses (double short arrows) and to the superior petrosal
sinuses (triple short arrows)

36. f) Treatment :
1-Aims of Treatment
2-Risks and Benefits of Balloon
Embolisation
3-Preprocedure Assessment
4-Endovascular Treatments

37. 1-Aims of Treatment :
-The aim of treatment is to occlude the connection
between ICA and the cavernous sinus
-An inflatable detachable balloon , mounted on a
flexible catheter , can be ‘floated’ through the
fistula
-Once through and in the cavernous sinus , it is
inflated to close the arterial breach from the
venous side and then detached
-This is one of the most rewarding treatments in
the whole of our repertoire because the
angiographic result is immediate ; the patient
reports relief of the bruit and signs of orbital
congestion reduce within hours

38. 2-Risks and Benefits of Balloon Embolisation :
-Cure rates of 85-95% have been reported with
immediate resolution of bruit , normalization of
intraocular pressure within 48 h and resolution of
orbital congestion in 7-10 days
-On the other hand , two major risks are
associated with balloon embolisation , these are:
a) Cerebral ischaemic symptoms or infarction
caused by obstruction to the ICA
b) Exacerbation of venous hypertension

39. -First , closure of the fistula may cause (by design
or inadvertently) ICA occlusion
-In most cases , the patient may tolerate this
because the fistula has already reduced the
effective blood supply to the brain from the ICA ,
but functional testing prior to embolisation
should be considered
-The risk to the cerebral blood supply is greater if
the treatment is performed transarterially
because of the risk of distal migration of the
balloon

40. -The second major concern is paradoxical
exacerbation of orbital congestion
because of failure to completely close the
fistula or because of induced thrombosis in
large orbital veins leads to extensive
orbital thrombophlebitis which may
endanger vision , the patient should be
warned that swelling may temporarily
worsen after ‘successful’ treatment

41. -Other risks involve damage to the artery or veins
during catheterization and delayed recurrence of
the fistula
-The latter occurs mostly in the first few days after
treatment due to incomplete closure or
premature balloon deflation
-Delayed cranial pain is associated with
enlargement of silicone balloons as a result of
osmotic pressure differences between the fluid
(i.e. saline) used to inflate them and body fluids ,
this complication has been managed by
percutaneous trans-foramen ovale or trans-
sphenoidal puncture and deflation of the balloon

42. 3-Preprocedure Assessment : DSA
-A six-vessel angiogram is recommended for
a complete understanding of the fistula
morphology
-This should be with high-frame-rate
angiography , because the hole is
obscured by rapid contrast filling of the
cavernous sinus
-Injection into the contralateral ICA or a
vertebral artery with compression of the
ipsilateral ICA is performed

43. -It is important to demonstrate the integrity of the
circle of Willis and exclude other lesions (e.g.
pseudoaneurysm or CCF of the contralateral
sinus)
-External carotid artery injections are needed to
exclude a coexisting DAVF and development of
collaterals
-When trauma has ruptured a branch of the
inferolateral trunk , the fistula may be fed by
meningeal branches of the ECA.
-3D reconstruction of the angiograms is very useful
in identifying the fistula point(s) and is now
performed as a routine method of showing the
anatomy

44. 4-Endovascular Treatments :
-Endovascular treatment has replaced surgical
trapping and is required for virtually all CCFs
since visual loss has been reported in 26% of
untreated patients due to glaucoma , retinopathy
, optic neuropathy or corneal ulceration
-Though , it is often preferable to wait 1 or 2 weeks
following trauma or onset of spontaneous
fistulas , because delaying treatment allows the
fistula (morphology and flow) to stabilize and
collateral cerebral blood flow to develop

45. -However , some fistulas have clinical and
angiographic features that require treatment in
the acute phase
-Venous hypertension , within the draining
leptomeningeal and cortical veins , is a risk
factor for cerebral hemorrhage and is a common
reason for early intervention
-Progressive loss of vision or suspected ‘steal’ of
cerebral flow by the fistula are other instances
where emergency treatment should be
considered , and once IOP is consistently
elevated , definitive treatment should be
performed within 1 week

46. a) Medical Management
b) Transarterial Embolisation
c) Transvenous Embolisation
d) Postoperative Care
e) Follow-Up

47. a) Medical Management :
-Medical treatment should be given to protect the
cornea (if proptosis is severe) and simple
measures such as sleeping with the head
elevated are suggested
-Treatments to reduce IOP include topical
adrenaline or pilocarpine (with care) especially
in patients with a family history of glaucoma and
, if ineffective , with carbonic anhydrase
inhibitors (acetazolamide or methazolamide)

48. b) Transarterial Embolisation :
-The endovascular treatment techniques are
divided into transarterial and transvenous
approaches
-The transarterial route is generally
preferred because the venous route is
usually more difficult and is associated
with higher failure rates , for these reasons
, it should be considered second choice

49. 1-Balloons
2-Coils
3-Stent with or without Coils
4-Liquids Agents

50. 1-Balloons :
-Detachable balloons are made of either
latex or silicone and are mounted on 2-3 F
single catheter or 2 F/4 F coaxial systems
-They are introduced via a 6-9 F guiding
catheter , depending on the size of the
balloon
-Partial inflation of the balloon allows it to be
flow-guided through the fistula

51. -However , there were several potential
difficulties when using detachable balloons
, these are :
1-Unreliable detachment control
2-Flow-dependent navigation with only
limited control in positioning
3-Unpredictable volume variations

52. -Often a single balloon is adequate to achieve
complete occlusion of the fistula
-However , where there is a large venous
compartment within the cavernous sinus ,
typically seen in chronic CCFs , more balloons
will be needed
-The more balloons needed , the less compliant
the venous side becomes , and consequently ,
the greater the risk that the last balloon will
protrude into and occlude the ICA

53. -Alternatively , if a balloon will not pass through a small
fistula , the operator has the option of using it to occlude
the ICA at the site of the arterial hole , if functional
testing has predicted that the patient will tolerate the
occlusion
-Acutely after trauma , it may be best to defer ICA occlusion
until any cerebral swelling or subarachnoid hemorrhage
has resolved
-Temporary ICA occlusion with clinical testing is obviously
best , but if angiography demonstrates (i.e. delay in
venous filling between the two hemispheres of <2 s) that
an adequate collateral blood supply to the ipsilateral
hemisphere has been established , then occlusion can
be performed

54. -An alternative technique is to use a combination
of nondetachable and detachable balloons
-The first is inflated distal to the fistula both to
protect the distal circulation from migration of a
premature detached balloon and help to direct
the detachable balloon through the fistula
-If ICA occlusion is performed , deployment of
tandem balloons to insure against deflation is a
standard precaution
-The distal balloon is placed across the fistula or if
this is not possible , then the balloons are
deployed in the ICA at the level of the CCF to
ensure the artery is occluded above and below
the fistula entrance

55. 2-Coils :
-Transarterial packing of the cavernous sinus with
coils is performed after a microcatheter has
been passed through the fistula
-This technique is indicated if the fistula is too
small to permit a balloon to pass into the sinus
-Packing is best performed with highly
thrombogenic coils (e.g. fibre coils or hydrogel-
coated coils)
-The technique involves packing the sinus
adjacent to the fistula as densely as possible
-Though technically easier than using a balloon ,
its main drawback is the risk of incomplete
closure and redirection of the CCF drainage or
recurrence

56. 3-Stent with or without Coils :
-The use of a stent to ‘reinforce’ coils placed within
the sinus is a logical extension of the technical
possibilities , and high-metal-density (low-
porosity) stents are a logical choice
-The stent is deployed in the ICA at the fistula site ,
and coils introduced either transarterially or
transvenously into the sinus
-There have been a few reports of the successful
use of covered stents in the cavernous ICA , but
given the stiffness of current stents , deployment
is technically difficult and the combination of
stent and coil reported more often

57. 4-Liquids Agents :
-N-butyl cyanoacrylate (NBCA) was first used to
treat recurrent CCF when a balloon had deflated
or coils had been inadequate to contain the
fistula
-In this situation , a small quantity of liquid may be
adequate to close the remnant with little risk of
NBCA refluxing into the ICA and to preserve
patency of the ICA
-More recently , reports using Onyx (ev3) , and a
nondetachable balloon placed in the ICA to
protect its lumen during injections , have been
described
-The use of combinations of techniques has
improved the cure rates of endovascular
treatments

58. c) Transvenous Embolisation :
-About 5% of CCFs have more than one
communication between the ICA and the
cavernous sinus which makes transarterial
treatment without stents difficult
-In this situation and when the transarterial route is
considered impossible , the transvenous route is
appropriate
-Access to the cavernous sinus is via the inferior
petrosal sinus , superior ophthalmic vein or even
the pterygoid plexus

59. -Access to the cavernous sinus through the inferior petrosal
sinus is more straightforward than via the SOV
-Direct puncture of the SOV should be avoided in CCF
because it risks causing uncontrollable hemorrhage in
the orbit
-Once in the cavernous sinus the catheter tip should ideally
be positioned adjacent to the fistula but navigating within
the sinus is often difficult
-It may then become necessary to pack the whole sinus
with coils , and care must be taken to avoid partial
closure of the sinus/fistula and redirection of blood flow
to cerebral veins

60. -Redirection of drainage to orbital veins may
exacerbate or cause a rise in venous pressure
within the orbit and threaten vision
-Therefore , embolisation should be planned to
exclude orbital or subarachnoid veins first
-Transvenous packing with coils is slow and
occlusion of the IPS (or other access route)
should be deferred until the operator is confident
that the CCF is closed and that orbital and any
cerebral veins have been disconnected

61. -As for transarterial embolisation , it is performed
with thrombogenic coils (e.g. fibre coils)
-Care should be taken using fibre coils or
hydrogel-coated coils because swelling of the
thrombosed sinus may cause cranial nerve
palsy or pain
-Liquids agents , and in particular Onyx , are an
effective alternative to coils in this situation

62. d) Postoperative Care :
-A minimum period of 48 h bed rest is
recommended with analgesia prescribed
depending on the severity and frequency of
headache
-Pain is a common complaint due to meningeal or
vessel wall stimulation
-Temporary worsening of ophthalmoplegia and
orbital swelling can usually be managed with
medical therapy

63. -The extent of exophthalmos and ophthalmoplegia
should be carefully monitored and auscultation
performed to monitor bruit (which usually
disappears as soon as the fistula is closed)
-If the fistula reopens , the bruit reappears
-A simple technique after balloon placement is to
perform a cranial radiograph in two projections
-This can be used as a baseline against which
future comparison can be made to assess for
any volume changes

64. e) Follow-Up :
-A suggested regime is for a review at 3 months to assess
vision and to ensure continued symptomatic
improvement
-It is doubtful whether delayed follow-up imaging studies
are needed since a CCF that is still occluded 4-5 days
after embolisation is unlikely to recur
-In some centers , catheter angiograms are performed
before the patient leaves hospital , but increasingly , MRI
is used at this stage (i.e. a baseline study) and then
repeated after 3-6 months to confirm satisfactory
resolution of soft tissue swelling , reduction in size of the
SOV and the cavernous sinus