Neuroangio Internal carotid artery and its endovascular aspect

1. Neuroangio of ICA & its
Endovascular Aspect
Dr. Shahnawaz Alam
MCh-Neurosurgery
Moderated by:
Dr. V. C. Jha
HOD, Dept. of Neurosurgery

5.  Cervical Internal Carotid Artery: No branches, except Persistent hypoglossal artery/
Ascending pharyngeal artery.

6. • Persistence of the primitive trigeminal
artery (PPTA) is MC; 0.1 to 0.68%. In utero, it
supplies BA before the development of
PCOM and VA.
• The PTA arises from the junction between the
petrous and the cavernous segment of the
ICA and middle or distal portion of BA; runs
posterolaterally along CN V or crosses over or
through DS.
• Associated with intracranial aneurysms,
AVM/CCF/TN/cerebellar hemangioblastoma.
• It is frequently associated with BA hypoplasia.
• Moreover, during the planning of surgical
approaches to the skull base, it is important to
evaluate the vascular anatomy of the sellar
and parasellar regions, searching for PTA.
• Several fetal anastomoses described b/w
Carotid and VB circulations; Hypoglossal,
trigeminal, otic, and proatlantal arteries are
examples of variant anatomical arterial
communications between the anterior and
posterior circulation.
• These anastomoses usually revert while P1
segment develops; However, these primitive
intracranial embryonic anastomoses can
occasionally persist in adulthood.

7. Significant from an endovascular access
standpoint, presenting challenges for distal
catheterization and delivery of larger caliber
devices; less problematic, as distal support
catheter technology rapidly improves.
Cervical Internal Carotid
Artery Loops
Retropharyngeal ICA Webs
Carotid Dissection

8. • The vessel has a characteristic lateral swing within the petrous bone (red arrows), bringing it into the
middle ear cavity, which can be appreciated on MR, CT, and angio. This variant comes up with
unfortunate regularity as a middle ear “pulsatile mass”.
Aberrant Carotid Artery
 Ascending pharyngeal reconstitution
of the true ICA in the petrous
segment, due to cervical ICA
agenesis. The aberrant carotid is
made up of the ascending pharyngeal
artery, its inferior tympanic branch,
and the caroticotympanic branch of
the ICA.

9. Aneurysms: In cervical ICA, these are typically of dissecting type, and
therefore pseudoaneurysms (white arrow); either asymptomatic or clinically
benign; when particularly large, act as embolic sources.

10.  Petrous segment- Carotidotympanic/ mandibulovidian Br.

11. Purple arrow demonstrating a small mandibulovidian artery. Notice how the petrous carotid often appears somewhat
attenuated and mottled due to overlap of the petrous bone, compared with the uniform dark color of the cervical and
cavernous segments: not to be confused with thrombus.

12. CAVERNOUS SEGMENT
• The posterior cavernous (dark blue) sinus is well-developed, receiving a large superficial sylvian /
sphenoparietal sinus tributary (orange), allowing one to visualize the proximal boundary of the cavernous
sinus (yellow arrow) as a line, against the background of the arterial phase. The inferior petrosal sinus is
marked by light blue arrow.

14. • MHT: Originating from the proximal cavernous segment of the ICA,
the MHT may come off as a single trunk or a collection of vessels.
• MHT vessels supply the posterior pituitary and portions of the
clivus, CN III, IV, V, and VI, pituitary gland, tentorium cerebelli,
and adjacent dura.
• Extensive collateral pathways exist with the ILT, MMA, and
hypoglossal branch of the ascending pharyngeal artery.
 A:MHT;
 B: Lateral Tentorial Artery along the lateral
edge of the tentorium, and in hemodynamic
balance with petrosquamosal branches (L) of
the MMA and Occipital Artery (O);
 C: Marginal Tentorial Artery a.k.a.
Bernasconi-Cassinari along the free edge;
 D: Inferior Hypophyseal Artery, branching
into: E: Hypophyseal branches supplying the
posterior and parts of anterior pituitary and
anastomosing with each other, F: Inferior Clival
Branch descending along the dorsum sella
where it is in hemodynamic balance with the
ascending clival braches (K) of the Ascending
Pharyngeal A.
 G: Lateral Clival artery, branching into:H:
Lateral Branch of the Lateral Clival artery
which runs alongside the Superior Petrosal
Sinus; I: Medial Branch of the Lateral Clival
Artery which runs alongside the Inferior
Petrosal Sinus and is in balance with Jugular
branches (J) of the Ascending Pharyngeal
 The checkered vessel connecting MHT with
the Basilar Artery (P) is the Trigeminal Artery,
which may come off the MHT or ILT.
 Important anastomoses also include branches
of the ILT (N) such as recurrent marginal artery,
the foramen lacerum branch of the Middle
Meningeal Artery (M), and Occipital Artery (O).

15. ILT(A) and important anastomoses
 B) Recurrent branch of the ILT: courses
along CN IV, and collateralizes with branches
of the MHT. Not rarely it annexes the territory
of marginal tentorial (G) or lateral tentorial (F)
arteries which more commonly come off the
ILT.
 C) Anteromedial branch: a very important
branch, this is a vestige of the primitive dorsal
ophthalmic artery which in very early
embryonic life supplied the orbit together with
primitive ventral ophthalmic artery. This artery
is hemodynamic balance with the recurrent
meningeal branch (N) of the ophthalmic artery
(M). Very rarely, when proximal ophthalmic
(M) is absent, this branch (C) can reconstitute
the ophthalmic artery, although more
commonly the middle meningeal artery fulfills
this role through its ophthalmic branch (K).
 D) Artery to the foramen rotundum; It collateralizes with foramen rotundum branch of the IMAX (L), and is the primary
route of ICA reconstitution via the IMAX.
 E) Foramen ovale branch : supplies the appropriate foramen ovale nerve and collateralizes with the accessory
meningeal artery (J) and also with carotid branch of the ascending pharyngeal artery (H) coming up through foramen
ovale and cavernous branch (I) of the middle meningeal artery.
 The checkered vessel anastomosing with the basilar artery (N) is the trigeminal artery, which sometimes originates from
the region of the ILT.

16.  Inferior Hypophyseal Artery of the MHT opacifying the pituitary gland with a characteristic blush (no
adenoma here!).
 The branch to the pituitary is well seen on the AP projection usually best visualized in mid-arterial phase
and persisting into venous phase.
 The posteroinferior branch of the MHT classically supplies the neurohypophyisis and portions of the
adenohypophysis.

17.  The second important branch of the cavernous segment is ILT,
which supplies the floor of the middle cranial fossa, cranial nerves
of the cavernous sinus, and is in balance with the Middle and
Accessory Meningeal Arteries.
 Therefore, it is a potential conduit to the ophthalmic artery,
expressed in its full prominence as the dorsal ophthalmic (red
arrow).
 The important MHT arises from the
genu (bend) of this segment; supply the
hypophysis, with a characteristic early
blush and early venous phase; Artery of
Bernasconi-Cassinari comes from there
also.

18.  ANEURYSMS: Non-traumatic cavernous aneurysms fusiform; Strong female
predominance; Preferentially expand laterally; CF: CN III, IV, VI palsy, or CC fistula; if
medial growth- life threatening epistaxis.
Various measurements have been made as part of Pipeline embolization planning;
center DSA frontal oblique projection image with additional careful measurements;
image on right demonstrates a Pipeline construct of multiple overlapping devices.

19.  Transitional (Clinoid) Segment

20. Stepwise dissection of the roof of the cavernous sinus-Superior view

21. Aneurysms

22.  Ophthalmic Segment
• Lateral projection views
(top row) and frontal +
lateral DSA of RT ICA
injection, demonstrating
ophthalmic artery origin
from anterior genu of the
ICA, proximal to its usual
location- the ostium may
be located within the
cavernous or transitional
segments, but is definitely
too distal for the ILT.

23. Dorsal Ophthl A. Ventral Ophthl A.

24. Meningo-Ophthalmic artery

25. Hypophyseal Segment
• The superior hypophyseal arteries
arise from the medial or
inferomedial part of the artery,
notably supplying the hypophysis
and, potentially, portions of the
optic apparatus.
• Frontal and lateral projection views
of left ICA injection, showing an
irregular, superolaterally-
projecting hypophyseal segment
aneurysm. Its relationship to the
superior hypophyeal arteries is
unclear.
• Circuminfundibular Anastomosis

26. • Blister aneurysm of the hypophyseal segment ; The days of angio-negative SAH, with subsequent discovery of an
occult saccular aneurysm may be waning. The blister kind is one where follow-up angio is key.
• On day presentation, there is impressive SAH. Day 1 angio shows very subtle spasm on the hypophyseal
segment. Day 5 angio demonstrates much more spasm in the hypophyseal segment and proximal MCA/ACA (not
shown). An oblique view of the hypophyseal segment uncovers the nasty, crater-like blister aneurysm.

27.  Paraophthalmic Segment
• Three segments (transitional, cavernous, and hypophyseal) into a single paraophthalmic segment.
PCOM Segment
• The communicating segment is defined by Bouthillier as extending from the PCOM to carotid
bifurcation, thus including the choroidal artery and ICA distal to it.
• Classically, PCOM aneurysms arise just distal to PCOM ostium, from the posterolateral ICA wall,
and initially projects posterolaterally.
• Lateral-pointing aneurysms may impact the third nerve, with the classic presenation of pupil-sparing
CN III palsy. PCOM aneurysms have notoriously high recurrence rates following endosaccular
coiling.
• Recurrence can also be treated by endoluminal methods (flow diversion). It is important to make a
distinction between PCOM and anterior choroidal segment aneurysms, particularly when parent
vessel sacrifice is performed (more often surgically).

28. Anterior choroidal segment

29. • 7T MRA; The Anterior Choroidal (light blue) can be traced perfectly well towards the choroid plexus (dark red).
• Notice amazing views of the lateral lenticulostriates (black), thalamogeniculate (dark blue double-sided arrow),
as well as posterior choroidal (white), posterior inferior temporal (green) and middle inferior temporal
(pink). The tentorium cerebelli enhancement (yellow).

30. • The course of AChA cisternal segment in
the paramesencephalic cistern (around the
cerebral peduncles) is superimposed
angiographically upon the middle segment
of BVOR.
• Infarcts: hemiplegia, due to its
participation in supply of the posterior limb
of IC; Other potential deficits include
various homonymous field cuts (optic
tracts, lateral geniculate), hemisensory
deficits (lateral thalamus), non-primary
motor movement changes, such as relief
of rigidity and less often tremor from
classic surgical ligations of the choroidal
artery in patients with Parkinson’s disease
(globus pallidus interna and Ansa
reticularis).
AChA perforators (purple) coming off the main trunk
(red) prior to the plexal point (light blue). A branch
to the choroid distal to the plexal point may be
present also (pink). The PCOM is orange (with a
large thalamic branch of its own). MHT (dark blue)
and ILT (green) branches are also visible.

31. Typical appearance of the anterior choroidal artery (red). The red arrow marks the plexal point where the
artery enters the choroidal fissure. A small artery distal to the anterior choroidal is present also
(orange) These arteries ascend thru the anterior perforated substance and may supply areas of
hypothalamus or optic tract — these are the arteries which hypertrophy in the moya-moya condition. An
MHT branch is also present (blue).

32.  The anterior choroidal is labeled in red, whereas a small PCOM, arising more proximally, is
marked with orange arrows. On the AP, you can see the hemispheric portion of the A Chor in
red, and the choroidal portion in purple.
Anterior Choroidal-PCOM confusion

33. • Frontal and lateral projection DSA views of left ICA injection, demonstrating typical puff of smoke Moya-
Moya appearance, achieved by reconstitution of the MCA via anterior choroidal (purple arrow) and
terminal segment (white arrow) perforators though the MCA lateral lenticulostriate group (black arrows).
• Notice proximal origin of the ophthalmic artery (distal cavernous or perhaps transitional segments) and a
hypertrophied recurrent meningeal branch of the ophthalmic artery (yellow).

34.  The Neurosurgical Atlas: inferior view of brain

35. References:-
1. http://neuroangio.org/
2. Rhoton cranial anatomy and Surgical Approaches.
3. Seven Aneurysms: Tenets and Techniques for Clipping by MD Michael T
Lawton
4. Clinical neuroanatomy, 7th edition Richard S. Snells
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