Vascular Surgery Flashcards
(175 cards)
1
Q
Define Acute mesenteric ischaemia
A
Sudden decrease in blood supply to the bowel resulting in bowel ischaemia and rapid gangrene
2
Q
List the common causes of acute mesenteric ischaemia
A
AAA Embolism Atherosclerosis (thrombus-in-situ) Shock Coagulopathy Malignancy Inflammatory disorders
3
Q
Describe clinical features of mesenteric ischaemia
A
- Generalised abdominal pain, out of proportion to other clinical findings
- Nausea and vomiting
- History indicating potential embolic sources
- Presentation similar to bowel perforation (late stage)
4
Q
What initial lab investigations would you order when considering mesenteric ischaemia?
A
- ABG - assess degree of acidosis and serum lactate
- Routine bloods: FBCs, U+Es, Clotting screen, LFTs, G+S
- Amylase (will be raised)
5
Q
What is the diagnostic test for acute mesenteric ischaemia?
A
CT angiography with IV contrast - Triple phase scan (thin slices taken in arterial phase)
6
Q
What will a CT scan of arterial bowel ischaemia show?
A
Oedematous bowel
Loss of bowel wall enhancement
Pneumatosis intestinalis
7
Q
What initial management is needed in acute mesenteric ischaemia?
A
Urgent resuscitation - IV fluids, catheter insertion, fluid balance chart
Broad spectrum antibiotics prescribed
Early ITU admission if significant acidosis
8
Q
What is the definitive management for ischaemic bowel?
A
- Excision of necrotic or non viable bowel
- Revascularisation of bowel - removal of thrombus or embolism via angioplasty
9
Q
What are the main complications of acute mesenteric ischaemia?
A
Bowel necrosis
Bowel perforation
10
Q
What is the mortality rate for acute mesenteric ischaemia?
A
50-80% (even with treatment)
11
Q
Define chronic mesenteric ischaemia
A
Lack of blood supply to the bowel which gradually deteriorates over time as a result of atherosclerosis in the CT, SMA or IMA
12
Q
Why do symptoms of chronic mesenteric ischaemia tend to occur after eating?
A
Increased demand of blood supply causes a transient ischaemia of the bowel
13
Q
What is the pathophysiology of chronic mesenteric ischaemia?
A
Gradual build up of atherosclerotic plaques within the lumen of at least two of the CT, SMA or IMA causing reduced blood flow and so ischaemia
14
Q
What are the main risk factors for chronic mesenteric ischaemia?
A
Smoking
Hypertension
Diabetes mellitus
Hypercholesterolaemia
15
Q
Describe the classical clinical features of chronic mesenteric ischaemia
A
Post prandial pain (10mins-4hrs post eating) Weight loss Concurrent vascular co morbidities Change in bowel habit N+V
16
Q
What is the gold standard diagnostic test for chronic mesenteric ischaemia?
A
CT angiography
17
Q
What are possible differentials for chronic non specific abdominal pain?
A
Chronic pancreatitis
Gallstone pathology
Peptic ulcer disease
Upper GI malignancy
18
Q
What medical management is indicated for chronic mesenteric ischaemia?
A
Antiplatelet agent
Statin
Lifestyle advice: weight loss, increasing exercise, smoking cessation
19
Q
What surgical intervention may be indicated in chronic mesenteric ischaemia?
A
Endovascular - mesenteric angioplasty with stenting
Open - endarterectomy or bypass
20
Q
When would surgical intervention be considered in chronic mesenteric ischaemia?
A
Severe disease
Progressive disease
Presence of debilitating symptoms (eg weight loss or malabsorption)
21
Q
What are the main complications of chronic mesenteric ischaemia?
A
Bowel infarction
Malabsorption
Concurrent CVS disease
22
Q
What is an aneurysm?
A
A persistent, abnormal dilation of an artery (>1.5x its normal diameter)
23
Q
Define an aneurysm
A
Persistent, abnormal dilation of an artery above 1.5x its normal diameter
24
Q
What possible causes are there of aneurysms?
A
Trauma
Infection
CT disease
Inflammatory disease (eg. Takayasu’s aortitis)
25
What is the gold standard imaging for peripheral and visceral aneurysms?
CT angiography
26
What is an alternative investigation for aneurysms to reduce kidney damage?
MR angiography
27
What imaging modality can be used for detection and follow up of aneurysms?
US duplex scan
28
What are the two most common peripheral artery aneurysms?
Popliteal artery
| Femoral artery
29
How may a popliteal artery aneurysm present?
Acute limb ischaemia
Intermittent claudication
Incidental finding
30
What are the main DDx for swelling in the popliteal fossa?
Politeal aneurysm
Bakers cyst
Lymphadenopathy
31
When should an asymptomatic popliteal aneurysm be treated?
If it is greater than 2cm
32
Why should all symptomatic popliteal aneurysms be treated?
High risk of embolisation
33
What surgical options are there for popliteal aneurysms?
- Endovascular repair (stent insertion)
| - Open repair (ligation of aneurysm or resection with a bypass graft)
34
What are the two major causes for development of a femoral artery aneurysm?
- Percutaneous vascular interventions
| - IVDU using the groin
35
What will a patient with femoral aneurysms normally present with?
Varying degrees of claudication or acute limb ischaemia
| * Often may have no symptoms beside swelling in the groin
36
What causes the signs and symptoms of femoral aneurysms?
Thrombosis, rupture or embolisation
37
What additional features may be seen in an IVDU patient with a femoral aneurysm?
Concurrent infection
38
What is the main treatment for a femoral artery aneurysm?
Open surgical repair
39
Which visceral arteries are most commonly affected by aneurysm formation?
- Splenic artery
- Hepatic artery
- Renal artery
40
How may a splenic artery aneurysm present?
Vague epigastric or LUQ pain
| Rupture --> severe abdo pain and haemodynamic compromise
41
What is first line management for a splenic artery aneurysm?
Endovascular repair
42
What are the common causes of a hepatic artery aneurysm?
Percutaneous instrumentation
Trauma
Degenerative disease
Post liver transplant
43
What may a symptomatic case of hepatic artery aneurysms present like?
Vague RUQ or epigastric pain
| Jaundice (if biliary obstruction)
44
What is first line management for hepatic artery aneurysms?
Endovascular repair --> best with embolisation or stent gradts
45
How may a patient with a symptomatic renal artery aneurysm present?
Haematuria
Resistent hypertension
Loin pain
46
What is the mainstay of treatment for a patient with a renal artery aneurysm?
Endovascular repair:
- Hilar --> with coils and self expanding stents
- Main artery --> stent
47
What are some of the risk factors for splenic artery aneurysms?
- Female
- Portal hypertension
- Pancreatitis
48
What is chronic limb ischaemia typically caused by?
Atherosclerosis (typically in the lower limbs)
49
What are the risk factors for chronic limb ischaemia?
```
Smoking
Diabetes mellitus
Hypertension
Hyperlipidaemia
Increasing age
Family history
Obesity + physical inactivity
```
50
Describe the fontaine classification of chronic leg ischamia
1 - Asymptomatic
2 - Intermittent claudication
3 - Ischaemic rest apin
4 - Ulceration or gangrene (or both)
51
Describe Buerger's test briefly
Lie the patient supine and raise their legs until they go pale - note the angle at which this happens (= Buerger's angle)
Then lower the legs until the colour returns/goes hyperaemic
52
What angle in Buerger's test will indicate severe chronic limb ischaemia?
Angle of less than 20 degrees
53
What is Leriche syndrome?
Form of peripheral arterial disease affecting the aortic bifurcation -- presents with buttock or thigh pain +/- erectile dysfunction
54
What three definitions are there for critical limb ischaemia?
- Ischaemic rest pain for >2 weeks, requiring opioids
- Presence of ischaemic lesions (or gangrene attributable to PVD)
- ABPI >0.5
55
What clinical features are seen on examination of a limb with critical ischaemia?
Pale, cold and pulseless limb
Hair loss, skin changes (eg. atrophic, ulceration, gangrene), thickened nails
56
What are the two major differentials for limb ischaemia?
```
Spinal stenosis ("neurogenic claudication")
Acute limb ischaemia
```
57
How may spinal stenosis be differentiated from chronic limb ischaemia?
Pain in the back radiating down lateral aspect of leg
| Symptoms worse on initial movement and relieved by sitting
58
How is the ABPI used to quantify the severity of chronic limb ischaemia?
```
Normal = >0.9
Mild = 0.8-0.9
Moderate = 0.5-0.8
Severe = <0.5
```
59
What may cause a falsely elevated ABPI?
Calcification and hardening of arteries
| >1.2
60
What initial investigation should be used for critical limb ischaemia?
Doppler ultrasound
61
What additional assessment should be done to assess for risk factors in chronic limb ischaemia?
Cardiovascular risk assessment
- BP
- Blood glucose
- Lipid profile
- ECG
62
What should be checked in a patient <50yrs with chronic limb ischaemia?
```
Thrombophillia screen
Homocysteine levels (higher is associated with CVS events)
```
63
What is the management for CVS risk factors in chronic limb ischaemia?
- Lifestyle advice
- Statin therapy
- Antiplatelet therapy
- Optimise diabetic control
64
What is first line management for intermittent claudication?
Enrolment into a local supervised exercise programme
65
When should surgical intervention be offered to patients with chronic limb ischaemia?
- If risk factor modification has been discussed
| - Supervised exercise has failed to improve symptoms
66
What are the two main surgical interventions used for chronic limb ischaemia?
- Angioplasty +/- stenting
- Bypass grafting (often for diffuse disease or younger)
- Combination (eg. surgery to clean lesion to allow access for angioplasty to another region)
67
When should amputation be considered in chronic limb ischaemia?
Unsuitable for revascularisation with ischaemia causing incurable symptoms or gangrene leading to sepsis
68
What complications are there of chronic limb ischaemia?
- Sepsis (secondary to infected gangrene)
- Acute on chronic ischaemia
- Amputation
- Reduced mobility
- Reduced QoL
69
What is the 5 year mortality rate of those diagnosed with chronic limb ischaemia?
~50%
70
Define acute limb ischaemia
Sudden decrease in limb perfusion that threatens the viability of the limb
71
What are the three main classifications of cause for acute limb ischaemia?
- Thrombosis in situ
- Embolisation
- Trauma
72
What are the 6 P's of acute limb ischaemia?
```
Pain
Pallor
Pulselessness
Parasthesia
Perishingly cold
Paralysis
```
73
How can you identify an embolic occlusion as the cause of acute limb ischaemia?
Normal and pulsatile contralateral limb
74
After what time period is presentation with acute limb ischaemia likely to result in paralysis?
>6hrs post symptoms onset
75
If both arterial and venous doppler are audible in acute limb ischaemia, what category is it?
I - Viable
76
What are the main DDx for acute limb ischaemia?
- Critical chronic limb ischaemia
- Acute DVT
- Spinal cord or peripheral nerve compression
77
Why is a serum lactate indicated in acute limb ischaemia?
Assess level of ischaemia
78
What initial investigation is used for acute limb ischaemia?
Doppler USS of both limbs
79
When should a CT angiogram be done in acute limb ischaemia?
If the limb is considered salvageable - identifies anatomical location of occlusion
80
What is the immediate management for a patient with acute limb ischaemia?
High flow o2 + adequate IV access
| **Therapeutic dose of heparin or bolus dose then heparin infusion
81
How are Rutherford stage 2a and 2b differentiated in acute limb ischaemia?
```
2a = minimal sensory loss
2b = sensory loss i more than toes + rest pain
```
82
What is conservative management for acute limb ischaemia?
Prolonged course of heparin (only for Rutherford 1 and 2a)
83
What surgical intervention is used for embolic acute limb ischaemia?
- Embolectomy via a Fogarty catheter
- Local intra-arterial thrombolysis
- Bypass surgery
84
What surgical intervention is used for thrombotic acute limb ischaemia?
- Local intra-arterial thrombolysis
- Angioplasty
- Bypass surgery
85
What will irreversible limb ischaemia look like?
Mottled, non blanching limb with hard, woody muscles
86
What long term management is needed for acute limb ischaemia?
- Reduction of CVS mortality risk
- Antiplatelets
- ?Anticoagulation
87
What is the mortality rate of acute limb ischaemia?
~20%
88
What are the complications of acute limb ischaemia?
- Reperfusion injury
- Compartment syndrome
- Hyperkalaemia
- Acidosis
- AKI (from myoglobin release)
89
What is the gold standard investigation for acute limb ischaemia?
CT angiography
90
Define varicose veins
Tortuous dilated segments of veins associated with valvular incompetence, permitting blood flow from the deep venous system into the superficial
91
What is the result of blood flow from the deep venous system into the superficial venous system?
Venous hypertension and dilation of superficial veins
92
List the common secondary causes of varicose veins
DVT
Pelvic masses (eg. Pregnancy, uterine fibroids, ovarian masses)
AV malformations
93
List the four major risk factors for the development of varicose veins
- Prolonged standing
- Obesity
- Pregnancy
- Family history
94
What will patients with varicose veins usually present with?
Cosmetic issues (eg visible veins or discolouration)
Pain
Aching
Swelling (often worse on standing)
95
What is seen on examination of a patient with varicose veins?
Varicosities along course of great and/or short saphenous veins
Features of venous insufficiency
96
What are some features of venous insufficiency?
```
Oedema
Varicose eczema
Thrombophlebitis
Ulcers (often over medial maleolus)
Haemosiderin skin staining
Lipodermatosclerosis
Atrophie blanche
```
97
What is a saphena varix?
Dilation of the saphenous vein at the saphenofemoral junction
Displays a cough impulse —> often mistaken for a femoral hernia
98
What system is used for classification of varicose veins?
CEAP
- Clinical features
- aEtiology
- Anatomical
- Pathophysiology
99
What is the gold standard investigation for varicose veins?
Duplex ultrasound
100
Name some non-invasive treatments for varicose veins
Patient education - avoid prolonged standing, weight loss + exercise
Compression stockings
Four layer bandaging (for venous ulceration)
101
What are the criteria for surgical referral with varicose veins?
- Symptomatic primary or recurrent varicose veins
- Lower limb skin changes from venous insufficiency
- Superficial vein thrombosis with suspected venous incompetence
- Venous leg ulcer
102
What are the main surgical treatment options for varicose veins?
- Vein ligation, stripping and allusion
- Foam scleropathy
- Thermal ablation
103
What are the main complications of varicose veins?
```
Haemorrhage
Thrombophlebitis
DVT
Disease recurrence
Nerve damage
```
104
What does the term chronic venous insufficiency encompass?
DVT
Valvular insufficiency
Varicose veins
105
What is deep venous insufficiency characterised by?
Valvular reflux
Venous hypertension
Obstruction
106
What is meant by primary causes of deep venous insufficiency?
Underlying defect in the vein wall or valvular component eg. Congenital defects + CT disorders
107
What is meant by secondary causes of deep venous insufficiency?
Defects occur secondary to damage
| Eg. Post-thrombotic disease, post-phlebitis disease, venous outflow obstruction + trauma
108
List the main risk factors for deep venous insufficiency
```
Increasing age
Female
Pregnancy
Previous DVT or phlebitis
Obesity
Smoking
```
109
Describe a classical presentation of deep venous insufficiency
Chronically swollen lower limbs
Aching, pruritic and painful
Venous claudication - bursting pain and tightness on walking resolving on leg elevation
110
What signs may be seen on a patient with deep venous insufficiency?
```
Varicose eczema
Thrombophlebitis
Haemosiderin skin staining
Lipodermatosclerosis
Atrophie Blanche
+ possible dependent oedema and venous ulcers
```
111
What are the symptoms of post thrombotic syndrome?
- Heaviness
- Cramping
- Pain
- Pruritis
- Paraesthesia
- Pretibial oedema
- Skin induration
- Hyperpigmentation
- Venous entasis
- Ulceration
112
What scale is used to monitor the degree of post thrombotic syndrome?
Villalta scale - assesses progression with treatment
113
What is the primary investigation for deep venous insufficiency? What is it looking for?
Doppler USS
| Extent of venous reflux, sites of stenosis and presence of DVT or varicose veins
114
What investigation should be done before compression therapy is initiated?
- Documentation of foot pulses
| - ABPI
115
What conservative management is there for deep venous insufficiency?
- Compression stockings
- Analgesic control
- 4 layer bandage for venous ulcer
116
When may venous stunting be used for deep venous insufficiency?
Severe post thrombotic syndrome with occluded iliac veins
117
What are common complications of deep venous insufficiency?
- Swelling
- Recurrent cellulitis
- Chronic pain
- Ulceration
118
What are the serious complications of deep venous insufficiency?
- DVT
- Secondary lymphoedema
- Varicose veins
119
What is subclavian steal syndrome?
Neurological deficits occurring when there is increased blood supply to the affected arm
—> secondary to a proximal stenosing lesion or occlusion in the subclavian artery
120
How is the blood supply redirected in subclavian steal syndrome?
Blood is drawn from collateral circulation causing a reversed blood flow in the ipsilateral vertebral artery
121
What are the common causes of subclavian steal syndrome?
- Atherosclerosis **
- Vasculitis
- Thoracic outlet syndrome
- Complications post aortic coarctation repair
122
What are the main clinical features of subclavian steal syndrome?
- Arm claudication
| - Cerebral symptoms eg. Vertigo, diplopia, dysphagia, visual loss, syncope
123
What initial investigation is usually used for subclavian steal syndrome? What will it show?
Duplex USS
| Shows retrograde flow in the affected vertebral artery during exercise
124
Why is a CXR done in subclavian steal syndrome?
Assess for any external compression on the subclavian artery
125
What is the definitive investigation for subclavian steal syndrome?
CT angiography (or MR angiography)
126
Describe the three grades of subclavian steal syndrome
Pre-subclavian steal: demonstrating purely a reduced anterograde vertebral flow
Intermittent alternating flow: antegrade flow in diastolic phase, retrograde flow in systolic
Advanced disease: permanent retrograde flow
127
What is the management for subclavian steal syndrome?
- Antiplatelet and statin therapy
- Address modifiable CVS risk factors
- Surgical: endovascular or bypass
128
When is bypass surgery indicated for subclavian steal syndrome?
Longer or distal occlusions
129
What does 'carotid artery disease' refer to?
Build up of atherosclerotic plaque in one or both of common and internal carotid arteries
130
How is carotid artery disease classified?
Radiologically based on the degree of stenosis
131
How will symptomatic carotid artery disease present?
Focal neurological deficit
- TIA
- Stroke
132
What are the main vascular DDx of carotid artery disease?
- Carotid dissection
- Thrombotic occlusion of carotid artery
- Fibromuscular dysplasia
- Vasculitis
133
What is fibromuscular dysplasia?
Hypertrophy of vessel wall causing stenosis of the artery
134
What initial investigations are indicated for any stroke patient?
- Urgent CT head
- Bloods: FBC, U&Es, Coag, Lipid profile, Glucose
- ECG
135
What is the role of CT angiography in carotid artery disease?
Gives percentage stenosis and characterises diseased portion of vessel for surgical intervention
136
What is indicated for ischaemic stroke prevention?
Carotid endarterectomy
137
What are the risks associated with carotid endarterectomy?
- Stroke
- Nerve damage (CN 9, 10, 12)
- MI
- Bleeding
- Infection
138
Define an aneurysm
Abnormal dilation of a blood vessel by >50% of its normal diameter
139
Define an abdominal aortic aneurysm
Dilation of the abdominal aorta >3cm
140
What possible causes are there for development of an AAA?
- Atherosclerosis
- Trauma
- Infection
- CT disorders eg. Marfan’s, Ehler’s Danlos, Loey Dietz
- Inflammatory disease eg. Takayasu’s aortitis
141
What are the main risk factors for AAA?
- Smoking
- Hypertension
- Hyperlipidaemia
- FHx
- Male
- increasing age
142
How may a AAA present?
- Incidental finding/on screening
- Abdominal pain
- Back/Loin pain
- Distal embolisation producing limb ischaemia
- Aortoenteric fistula
143
Briefly outline the National AAA screening programme
Offer an abdominal USS for all men aged 65
- 3-4.4cm --> Yearly screening
- 4.5-5.4cm --> Scan every 3 months
- >5.5cm dilation --> consider for surgery
144
Give the main DDx for a symptomatic AAA
- Renal colic *
| - Abdominal pathology eg diverticulitis, IBD, GI haemorrhage, appendicitis, ovarian torsion/rupture, splenic infarct
145
What investigation is done to follow up a diagnosis of a AAA on a USS?
CT scan with contrast
146
What lifestyle advice can be given to patients with a small/medium AAA?
- Smoking cessation
- Improve BP control
- Commence statin and aspirin therapy
- Weight loss
- Increase exercise
147
What indications are there for surgical intervention of a AAA?
- AAA >5.5cm
- AAA expanding at >1cm per year
- Symptomatic AAA in an otherwise fit patient
148
What are the main surgical options for AAA?
- Open repair
| - Endovascular repair
149
Compare the outcomes of open and endovascular repair for a AAA
Similar long term outcomes at 2 years
Endovascular repair has improved short term outcomes - reduced hospital stay and 30 day mortality but higher rate of intervention + aneurysm rupture
150
What is involved in an open repair for a AAA?
Midline laparotomy or long transverse incision - clamp either end and remove the segment - then replace with a prosthetic graft
151
What does endovascular repair involve for a AAA?
Introduction of a graft via the femoral arteries + fixing a stent across the aneurysm
152
What is an endovascular leak?
Complication of endovascular repair - incomplete seal forms around the aneurysm resulting in blood leaking around the graft
153
What are the main complications of a AAA?
- Rupture
- Retroperitoneal leak
- Embolisation
- Aortoduodenal fistula
154
How can a AAA rupture present?
- Abdominal pain
- Back pain
- Syncope
- Vomiting
155
What is the classic triad for a ruptured AAA?
- Flank or Back Pain
- Hypotension
- Pulsatile abdominal mass
156
How is the BP controlled in a ruptured AAA?
Permissive hypotension - maintain at <100mmHg
| — Raised BP can dislodge any clots and precipitate further bleeding
157
What is the management for a ruptured AAA?
A-E
- If unstable --> immediate transfer to theatre for open surgical repair
- If stable --> CT angiogram to determine if endovascular repair is suitable
158
Define an aortic dissection
Tear in the intimal layer of the aortic wall --> causes blood to flow between and so causing a split between the tunica intima and tunica media
159
What is the difference between the timescale for an acute and chronic aortic dissection?
```
Acute = diagnosed <14 days
Chronic = diagnosed >14 days
```
160
How does an anterograde aortic dissection propagate?
Towards the iliac arteries
161
How does a retrograde aortic dissection propagate? What can this cause?
Towards the aortic valve --> valvular prolapse, bleeding into the pericardium + cardiac tamponade
162
What two classification systems can be used for an aortic dissection?
- DeBakey
| - Stanford
163
Briefly describe the DeBakey classification for aortic dissections
Type 1 - originates in ascending aorta + propagates to at least the aortic arch
Type 2 - confined to ascending aorta
Type 3 - originates distal to subclavian artery in descending aorta
- 3a = extension distally to diaphragm
- 3b = extension beyond diaphragm to abdominal aorta
164
Briefly describe the Stanford classification of aortic dissection
Group A - DeBakey 1+2
| Group B - DeBakey 3
165
What risk factors are there for aortic dissections?
- Hypertension
- Atherosclerotic disease
- Male gender
- CT disorder eg. Marfan’s or Ehler’s Danlos
- Bicuspid aortic valve
166
How does an aortic dissection classically present?
Tearing chest pain, radiating to the back
167
What clinical signs are commonly seen for an aortic dissection?
- Tachycardia
- Hypotension
- New aortic regurgitation murmur
- Signs of end organ hypoperfusion
168
What are the main DDx for an aortic dissection?
- MI
- PE
- Pericarditis
- MSK back pain
169
What first line imaging is there for an aortic dissection? Why?
CT angiogram - allows classification, establish anatomy and assists surgical planning
170
How is management of aortic dissection different by classification?
Stanford Type A - surgical
| Stanford Type B - medical
171
What long term management is there for aortic dissections?
- Lifelong antihypertensive therapy
| - Surveillance imagine (1, 3, + 12 months post discharge and then at 6-12 month intervals)
172
What surgical management is indicated for aortic dissections?
Removal of ascending aorta + replacement with synthetic graft
+ ensure additional branches are re-implanted into the graft
173
What medical management is given for aortic dissections?
Management of hypertension (rapidly lower systolic pressure, pulse pressure + pulse rate --> minimise stress of dissection + limit further propagation)
174
When is surgical intervention indicated in a type b aortic dissection?
Complications eg
- Rupture
- Visceral or limb ischaemia
- Refractory pain
- Uncontrollable hypertension
175
What are the main complications of an aortic dissection?
- Aortic rupture
- Aortic regurgitation
- MI (secondary to coronary artery dissection)
- Cardiac tamponade
- Stroke/paraplegia (secondary to cerebral/spinal artery involvement)
