Chapter 97 - Vertebral artery dissection

Question 1

Percentage of stroke that are due to posterior circulation

Answer 1

25%

Question 2

Risk of stroke in 5 years with vertebrobasilar TIA and vertebral stenosis

Answer 2

22-35%

mortality 20-30%

Question 3

Vertebral artery segments

Answer 3

V1: vertebral origin from subclavian to C6 entry
V2: C6 to C2 inside intertransversarium muscle and cervical transverse process
V3: C2 to base of skull
V4: intracranial, intradural from alanto-occipital membrane to basilar artery

Question 4

Symptoms of vertebrobasilar ischemia

Answer 4

1) disequilibrium
2) vertigo
3) diplopia
4) cortical blindness
5) alternating paresthesia
6) tinnitus
7) dysarthria
8) quadriplegia
9) drop attacks
10) ataxia
11) perioral numbness

Question 5

Most common cause of posterior circulation stroke

Answer 5

1) large artery occlusive 32%
2) embolism cardiac 24%
3) embolism arterial 18%
4) penetrating artery disease 14%
5) vasospasm/migraine 2%
6) others 8%

Question 6

Frequency of posterior vascular occlusive lesions in descending frequency

Answer 6

Intracranial vertebral
Extracranial vertebral
Basilar

PCA

Innominate
Subclavian

Question 7

Hemodynamic low flow symptoms of vertebrobasilar

key points

Answer 7

1) more common than embolic (different from anterior circulation)
2) transient usually rarely infarct
3) basilar distribution more common
4) vertebral insufficiency requires bilateral disease, basilar disease, incomplete COW, subclavian steal

Question 8

Most common segment to have atherosclerotic disease

Answer 8

V1

usually smooth and fibrotic low embolic potential

Question 9

V2 segment compression caused by

Answer 9

1) rotation or extension of neck

2) abnormal entry at C4 and C5 by musculotendinous structures

Question 10

Most common location of vertebral AVF

Answer 10

V2

fixation of adventitia to periosteum of foramina –> vulnerable to luxation /subluxation injuries

Question 11

True vertebral aneurysm account for this much vertebral lesions

Answer 11

1%

almost all due to connective tissue disorders

Question 12

Common disease in V3 segment

Answer 12

1) trauma
2) dissection (most common area because artery most mobile and redundant)
3) AVF (AV aneurysm)
4) compression in pars atlantica (head extension or rotation)

Question 13

Symptoms of vertebral artery dissection

Answer 13

1) dizziness
2) vertigo
3) double vision
4) ataxia
5) dysarthria

Question 14

Vertebral artery dissection natural course

Answer 14

62% resolve

50% will have symptoms
21% mild; 25% severe; 4% death

no relationship between recanalization rate and neuro outcome

Question 15

V3 segment gets collaterals from

Answer 15

1) ECA occipital artery

2) subclavian via thyrocervical trunk

Question 16

Differential diagnosis for vertebrobasilar ischemia

Answer 16

1) arrhythmia
2) cardioemboli
3) labyrinthine dysfunction
4) tumor of cerebellopontine angle
5) antiHTN meds
6) cerebellar degeneration
7) myxedema
8) electrolyte and glycemic imbalance

Question 17

Percentage of people with left vert off arch

Answer 17

6%

Question 18

Other vertebral anomalies

Answer 18

Right vert off innominate or CCA (aberrant right subclavian)

entry transverse process at C7 instead of C6 (shorter V1 segment to work with)

Question 19

Vertebral treatment options depending on segment

Answer 19

V1: transposition to carotid or interposition bypass
V2: ligation; bypass if needed to V3
V3: bypass from carotid, subclavian or proximal vert; transposition of ECA or occipital artery
Suboccipital segment: resect C1 transverse process and posterior arch; bypass from distal ICA

Question 20

Transposition of proximal vert to CCA steps

Answer 20

1) 1 finger above clavicle over two heads of SCM - transverse incision
2) plastysmal flap
3) between two bellies of SCM
4) omohyoid divided
5) IJ retracted laterally
6) carotid exposed proximally
7) divide thoracic duct
8) dissect medial to prescalene fat pad
9) divide vertebral vein
10) dissect out the vertebral artery

Question 21

Distal vertebral artery reconstruction steps

Answer 21

1) anterior to SCM incision
2) dissect between IJ and SCM to find spinal accessory nerve
3) follow CN11 cranially until it crosses inf ront of transverse process of C1
4) remove fibrofatty tissue to identify levator scapulae muscle
5) identify the anterior ramus of C2
6) divide levator scapulae
7) Cut the C2 ramus before it branches (scalp numbness)
8) identify vertebral artery underneath
9) look out for occipital artery collateral

Question 22

Stroke rate for V1 reconstruction

Answer 22

0.9%

Question 23

Combined CEA and V1 reconstruction stroke rate

Answer 23

5.7%

Question 24

Distal V3 reconstruction complications

Answer 24

Stroke/death 3%
graft thrombosis 8%
spinal accessory nerve injury 2%

Question 25

5 and 10 year patency of V1 or V3 reconstruction

Answer 25

V1 95 and 91%
V3 87 and 82%

symptom relief
V1 80%
V3 71%

Question 26

endovascular intervention for vert stroke rate

Answer 26

6.4% in 30 days

CAVATAS 2001 RCT found no strokes

Question 27

Restenosis after vert endo intervention

Answer 27

13% at 2.5 years

SSYLVIA trial found 50% restenosis at 6 months

systematic review found 23% restenosis