anterior choroidal artery course, clinical implications, angiography and surgical importance clinical features of aneurysm, AVM involving the anterior choridal artery

1. Anterior Choroidal Artery
Presented By:
Dr. Rahul Jain
SR-2 Neurosurgery
Moderated by:
Dr V. C. Jha
Dr Nitish Kumar
Dr Gaurav Verma

2. Introduction
• Usually arises from C4 as single artery, majority of
the time arising near origin of PComA than near
bifurcation.
• It measures ~1 mm in diameter.
• Variant anatomy
occasionally it may originate from
• internal carotid artery bifurcation
• middle cerebral artery
• posterior communicating artery
duplication of AChA is reported in ~5% of cases

3. Embryology
• AchA may be most prominent in its vascular supply
to the brain during the choroidal stage of
development, around five weeks.
• During this time, the vertebrobasilar system has yet
to develop, and the internal carotid arteries almost
exclusively supply the brain.
• Thus, the AchA provides cortical branches to the
temporal, parietal, and occipital lobes during this
early embryonic stage, which is later dominated by
the posterior cerebral artery in the adult human.

4. • Due to its prominence in early embryonic
development, the AchA does have various
anatomic variants that may exist as discussed.
• In such cases, collateral circulation may diminish,
and thus it is essential to keep the singular vessel
supplying that area patent.

5. Course
AChA arises from the posterior wall of the ICA
above the origin of the PComA. Initial segment
of the AChA is directed posteromedial behind
the internal carotid artery and passes
backward below the optic tract and lateral to
the PCA and cerebral peduncle
At the anterior margin of the lateral
geniculate body, the AChA again crosses the
optic tract from medial to lateral and passes
posterolateral through the crural cistern,
located between the cerebral peduncle and
uncus.

6. • The average length that the artery
follows the optic tract is 12 mm
(range, 5-25 mm).
• The AChA passes above the
posterior uncal segment and
enters the temporal horn by
passing through the choroidal
fissure located between the
thalamus above and fimbria of the
fornix below. (Plexal Point)
• enter the choroid plexus, courses
along the medial border of the
choroid plexus in close relation to
the lateral posterior choroidal
branches of the PCA.
• pass dorsally along the medial
border of the plexus, reaching the
foramen of Monro

7. AChA pursues an angulated course,
descending along the anterior
segment of the uncus, but at the
uncal apex it turns sharply upward,
reaching the upper part of the
posterior uncal segment before
entering the temporal horn.
The AChA can be divided into two segments:
• Cisternal segment: extends from its origin until the choroidal
fissure; measures ~2.5 cm (range 1.5-3.5 cm) in length. It
passes through carotid cistern, crural cistern and ambient
cistern before reaching the choroidal fissure 6,7.
• Intraventricular or plexal segment: one or more branches
that pass through the choroidal fissure to branch and enter
the choroid plexus of the temporal horn.

8. 7T MRI - Anterior Choroidal
(light blue) can be traced perfectly
well towards the choroid plexus
(dark red)
anterior choroidal 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 PComA is orange (with a large
thalamic branch of its own). MHT
(dark blue) and ILT (green)
branches are also visible.

9. Vascular territory
• cisternal segment
• deep brain structures
• posterior limb and retrolenticular part of
the internal capsule including optic
radiations
• lateral thalamus including lateral
geniculate nucleus
• optic tract
• lateral cerebral peduncle
• globus pallidus internus
• tail of caudate nucleus
• mesial temporal structures (uncus)
• head of hippocampus
• amygdala
• Intraventricular segment - choroid plexus of the
anterior part of the temporal horns

10. • Nearly half of hemispheres have anastomoses
between the PCA and AChA. The richest
anastomoses are those located on the surface of
the choroid plexus with the lateral posterior
choroidal branches of the PCA.
• Anastomoses between the AChA and PCA are also
found on the lateral surface of the lateral
geniculate body and on the temporal lobe near the
uncus.
• These complex and variable anastomoses make it
difficult to predict the effects of occlusion of a
single AChA, but explain some of the inconsistent
results of AChA occlusion.

11. • There is a marked interchangeability of the field of
supply of the AChA and the nearby branches of the
C4, PCA, PComA, and MCA.
• Within the internal capsule. If the PComA is small,
the anterior choroidal artery may take over its
normal area of supply to the genu and the anterior
third of the internal capsule, or if the AChA is small,
the field of supply of the PComA may enlarge to
supply the greater part of the posterior limb of the
internal capsule.

12. Surgical Considerations
Intradural exposure of the C4
• In exposing the C4 beyond the origin of the ophthalmic
artery, the surgeon often sees the AChA before the
PComA, although the AChA arises distal to the PComA.
• Three sets of anatomic circumstances
• the C4 passes upward in a posterolateral direction, placing
the origin of the AChA further lateral to the midline than the
origin of the PComA
• AChA commonly arises further laterally on the posterior wall
of the C4 portion than the PComA.
• AChA pursues a more lateral course than the PComA, atter is
most commonly directed in its initial course in a
posteromedial direction

13. Aneurysm
• Aneurysms at the junction of the
AChA and ICA account for 2%-
4% of all intracranial aneurysms
however, distal AChA aneurysms
are rare.
• point posteriorly or
posterolaterally, usually well
above the oculomotor nerve.
• Most distal AChA aneurysms are
located in the choroidal segment
beyond the plexal point and are
associated with MMD, whereas
AChA aneurysms in the cisternal
segment are extremely rare.

14. • Present with subarachnoid hemorrhage, however,
distal AChA aneurysms often present with isolated
medial temporal intracerebral hematoma with
intraventricular extension.
• Because the AChA is vulnerable, inadvertent
damage to and occlusion of the AChA during
clipping and embolization may have deleterious
clinical consequences.
• Compared with clipping, coiling AChA aneurysms
had a significantly lower incidence of AChA
infarction , in a study performed by Bohnstedt et al.
in 2013, the ischemic complication rate following
surgical treatment of AChA aneurysms was 12%,
whereas coiling AChA aneurysms as an alternative
to clipping was associated with a 5.5% risk of
ischemia.

15. • Treatments for distal AChA aneurysms are different
from those for proximal AChA aneurysms because
of their lack of accessibility and small size the
aneurysm location and the preservation of the
parent artery are two major prognostic factors.
• When distal AChA aneurysms are beyond the plexal
point, the AChA can be sacrificed or preserved, if
the treatment requires AChA occlusion,
preoperative provocative testing should be
considered.

16. Ach Artery Infarct
• triad of contralateral hemiparesis, hemianesthesia,
and hemianopia, in AChA syndrome.
• contralateral hemiplegia and hemianesthesia (to all
sensory modalities) results from infarction in the
posterior two-thirds of the posterior limb of the
internal capsule and the middle third of the
cerebral peduncle.
• homonomous hemianopsia of varying degrees
results from interruption of the supply to the origin
of the optic radiations, the optic tract, and part of
the lateral geniculate body.
• AChA infarcts can be divided into small vessel and
large vessel infarcts, and thrombolytic therapy may
be effective for large vessel infarcts.

17. Moyamoya disease
• chronic occlusive cerebrovascular disease
characterized by bilateral stenosis or occlusion at
the terminal portion of the ICA and the eponymous
vessels at the base of the brain.
• site of occlusion or stenosis can occur in one of the
following four sites:
1 the top of the ICA or A1 ACA or M1 MCA
2 distal to the AChA
3 between the AChA and posterior communicating
artery
4 proximal to the posterior communicating artery

18. • collaterals are more likely to arise from the choroidal
arteries; therefore, the AChA may act as a major
collateral route because it is frequently dilated and
exhibits abnormal extension.
• The angiographic findings of the AChA can be
considered grade 2 according to Suzuki's classification,
and the AChA shows dilation and extension beyond the
choroidal fissure.
• when it functions as a collateral vessel to increase
blood flow, the hemodynamic load in the vessels
supplying the walls of the posterior areas of the
ventricles and the periventricular region is increased.
• Under such a hemodynamically stressed state, the
dilated branches of the AChA may be more fragile, and
the choroidal arteries and their anastomotic channels
may rupture. In addition, an aneurysm could develop
from an outpouching of the vessel wall in some fragile
portions.

19. • Distal AChA aneurysms in MMD can be treated
endovascularly with embolization. However,
disturbing the MMD collaterals should be avoided
when using a liquid embolization material.
• AChA is a “double-edged sword” in MMD. On one
hand, the dilated AChA acts as collateral vessels to
prevent brain ischemia; on the other hand, due to
the resulting hemodynamic stress, the branches of
the AChA may rupture and even form an aneurysm
in the AChA.
• Following intracranial bleeding, both direct and
indirect revascularization may be effective for
preventing recurrent bleeding.

20. Brain tumors
• blood supply to particularly those located in the lateral
ventricle; include meningiomas, choroid papilloma and
gliomas.
• hypervascular nature of the lesions in the lateral ventricle
imposes challenges for surgical treatment; therefore,
obliterating the feeders from the AChA before surgery
could reduce hemorrhage and facilitate the surgery
• Since AChA feeds critical regions of the brain, migration
of embolic agents through the AChA might cause serious
neurological deficits.
• Successful embolization requires the catheter to enter
the plexal segment beyond the plexal point and during
the injection, the speed should be extremely slow to
avoid excessive reflux of the embolic agent.

21. Arteriovenous malformations
• AVMs fed by the AChA are difficult to treat because
surgical treatment can cause a high incidence of
neurological deficits.
• AVM embolization via the AChA may be an
appropriate treatment option prior to surgery and
radiation therapy or serve as a curative procedure.
• Microcatheter tip should be advanced distally
beyond the plexal point to avoid serious ischemic
complications.
• Approximately 38% of capsulo-thalamic arteries
arising from the AChA originate from the first part
of the plexal segment, and this variation could be
an important risk factor

22. • In contrast, embolization from the cisternal
segment of the AChA does not always result in
ischemic complications, suggesting a potential
collateral circulation.
• To minimize ischemic complications, some authors
recommend superselective provocative testing with
propofol using motor-evoked potential monitoring
to manage AVMs fed by the AChA.

23. Parkinson disease
• characterized by lesions in the basal ganglia
(predominantly in the substantia nigra), and symptoms
include tremor, bradykinesia, rigidity, and postural
instability.
• AChA may play a role in PD because, in rare cases, PD
may arise due to AChA territorial infarcts affecting the
basal ganglial structures and the striatal pre-synaptic
dopaminergic pathways resulting in Vascular
Parkinsonism
• in 1953, Cooper et al. reported dramatic amelioration
of parkinsonism after ligation of the AChA in 8 patients
with severely advanced disease and concluded that the
procedure had been invariably followed by the
disappearance of most of the rigidity and cogwheelism;
additionally, neither hemiplegia nor hemianesthesia
occurred.

24. Pial arteriovenous fistula
• cerebral pial arteriovenous fistula (PAVF) is a direct
connection between the intracranial artery and
vein without a nidus, and the vein often develops
venous pouches of different sizes.
• Cerebral PAVF should be considered congenital.
• Cerebral PAVF involving the AChA is extremely rare.
• Currently, endovascular management is the first-
line treatment of choice for PAVFs, and the goal is
to close feeders at the entry point to the vein.
• Coiling is a better choice than glue because the
AChA is too short to prevent dangerous reflux
during glue embolization.

25. Conclusion
• Although the AChA is a small thin artery, it supplies
an extremely critical region of the brain.
• The AChA can be involved in many diseases,
including aneurysm, brain infarct, MMD, brain
tumor, AVM and traumatic cerebral hemorrhage.
• During treatment for aneurysms, tumors, AVM or
AVF, the AChA cisternal segments should be
preserved as a pathway to prevent the infarction of
the critical regions of the brain that receive their
blood supply from the AChA.