vertebral artery anatomy with its course, branches and microdissection aspects along with endovascular aspects

1. Neuroangio of Vertebral Artery
& its Endovascular Aspect
Dr. Rahul Jain
Moderated by:
Dr. V. C. Jha
HOD, Dept. of Neurosurgery

2. Posterior circulation anatomy
• The vertebrobasilar arterial system receives only 20%
of cerebral blood flow and supplies the posterior
portion of the brain including the brainstem, the
thalami, the cerebellum and parts of the occipital and
temporal lobes

3. Posterior circulation is subdivided in proximal, middle and distal
intracranial territory, according to Caplan et al.

4. Vertebral arteries
• arise from the first part of subclavian arteries
• ascends the neck by passing through the foramlna in
the transverse processes of the upper six cervical
vertebrae
• It enters the skull through the foramen magnum and
pierces the dura mater and arachnoid to enter the
subarachnoid space.

5. • Both VAs join at the pontomedullary junction to
form the basilar artery
• VAs usually have a luminal diameter of 3–5 mm and
are conventionally divided into four segments

7. • V1 (the pretransverse segment): from the origin to
the transverse foramen of C6.
• V2 (the transverse segment): from the transverse
foramen of C6 to the transverse foramen of C2.

8. • V3 (the suboccipital segment): from the foramen
transversarium of C2 to the atlanto-occipital
membrane. This segment forms a loop that allows
free movements of the head and the neck
• V4 (the intracranial segment): from the point
where the VAs pierce the atlanto-occipital membrane
to their confluence to form the basilar artery at the
medullopontine junction

9. CT Angiographic images

10. • The intracranial part of each VA gives rise to the
following branches:
1. Meningeal branches
2. Posterior spinal artery – 1st intracranial branch
3. Anterior spinal artery
4. Posterior inferior cerebellar artery – 2nd
5. Medullary arteries

11. The lower cranial nerves (IX through XII) are intimately involved with the
VA and PICA vessels.

15. PICA
• Origin – vertebral artery near
the inferior olive Divided into
five segments:
1) anterior medullary,
2) lateral medullary,
3) tonsillomedullary
4) telovelotonsillar, and
5) cortical Bifurcation – medial
and lateral trunk (at
telovellartonsillar fissure)
• During surgery first three must
be preserved, last 2 may be
sacrificed with minimal deficit

16. • Usually arises ≈ 10mm distal to point where VA
becomes intradural, ≈ 15mm proximal to the
vertebrobasilar junction.
• Tonsillomedullary – contains caudal loop on angio
• Telovelotonsillar – contains cranial loop aka choroidal
point on angio
• If an aneurysm is located distal to this choroidal
point, occlusion of the parent vessel as a means
of treatment is generally considered safe.

17. • 3 branches
• a) Choroidal a. (BRANCH 1) arises from cranial loop
( choroidal point), ⇒ choroid plexus of 4th
• ventricle
• b) terminal branches:
• ● Tonsillohemispheric (BRANCH 2)
• ● Inferior vermian (BRANCH 3) inferior inflection =
copular point on angio

18. Normal anatomy of posterior circulation post contrast injection in
left vertebral artery, lateral view

21. Preoperative evaluation for
microsurgical treatment
• Imaging modality – CTA/MRA/DSA
• specific anatomic features should be inspected prior to surgical
treatment :
1. VAs – whether one is dominant
2. Level of PICA origin – intra or extra
3. Laterality of aneurysm – whether closer to midline
4. Site of PICA aneurysm – to determine whether parent vessel
sacrifice is an opton
5. Fetal PCA
6. Presence of small bilateral Pcomm arteries
7. Location of aneurysm with respect to occipital condyle and
jugular tubercle to determine amount of bone removal

24. References:-
1. Clinical neuroanatomy, 8th edition Richard S. Snells
2. Youmann and Winn’s Neurological Surgery 4th edition
3. Greenberg’s Handbook of Neurosurgery
4. Rhoton cranial anatomy and surgical approaches
THANK YOU