Chapter 97 - Vertebral artery dissection Flashcards
Percentage of stroke that are due to posterior circulation
25%
Risk of stroke in 5 years with vertebrobasilar TIA and vertebral stenosis
22-35%
mortality 20-30%
Vertebral artery segments
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
Symptoms of vertebrobasilar ischemia
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
Most common cause of posterior circulation stroke
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%
Frequency of posterior vascular occlusive lesions in descending frequency
Intracranial vertebral
Extracranial vertebral
Basilar
PCA
Innominate
Subclavian
Hemodynamic low flow symptoms of vertebrobasilar
key points
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
Most common segment to have atherosclerotic disease
V1
usually smooth and fibrotic low embolic potential
V2 segment compression caused by
1) rotation or extension of neck
2) abnormal entry at C4 and C5 by musculotendinous structures
Most common location of vertebral AVF
V2
fixation of adventitia to periosteum of foramina –> vulnerable to luxation /subluxation injuries
True vertebral aneurysm account for this much vertebral lesions
1%
almost all due to connective tissue disorders
Common disease in V3 segment
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)
Symptoms of vertebral artery dissection
1) dizziness
2) vertigo
3) double vision
4) ataxia
5) dysarthria
Vertebral artery dissection natural course
62% resolve
50% will have symptoms
21% mild; 25% severe; 4% death
no relationship between recanalization rate and neuro outcome
V3 segment gets collaterals from
1) ECA occipital artery
2) subclavian via thyrocervical trunk
Differential diagnosis for vertebrobasilar ischemia
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
Percentage of people with left vert off arch
6%
Other vertebral anomalies
Right vert off innominate or CCA (aberrant right subclavian)
entry transverse process at C7 instead of C6 (shorter V1 segment to work with)
Vertebral treatment options depending on segment
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
Transposition of proximal vert to CCA steps
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
Distal vertebral artery reconstruction steps
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
Stroke rate for V1 reconstruction
0.9%
Combined CEA and V1 reconstruction stroke rate
5.7%
Distal V3 reconstruction complications
Stroke/death 3%
graft thrombosis 8%
spinal accessory nerve injury 2%
5 and 10 year patency of V1 or V3 reconstruction
V1 95 and 91%
V3 87 and 82%
symptom relief
V1 80%
V3 71%
endovascular intervention for vert stroke rate
6.4% in 30 days
CAVATAS 2001 RCT found no strokes
Restenosis after vert endo intervention
13% at 2.5 years
SSYLVIA trial found 50% restenosis at 6 months
systematic review found 23% restenosis
