Chapter 55 - Cerebrovascular exposure

Question 1

Carotid exposure steps

Answer 1

1) 12-15 cm incision along anterior edge of SCM
2) extend laterally at angle of jaw to avoid parotid gland
3) avoid greater auricular nerve
4) avoid accessory (superior extent of incision neare SCM)
5) Dissect out IJ and ligate medial branches
6) Dissect along medial IJ and free branches to retract CN XII

Question 2

What are the vascular branches tethering CN XII

Answer 2

SCM branches of occipital artery

Question 3

Why avoid dissection of ECA far from the bifurcation

Answer 3

Superior laryngeal nerve runs behind it

Question 4

Retrojugular approach to carotid exposure pro and con

Answer 4

Con: decrease visualization of EIA
Pro: better ICA visualization, no need to divide veins or ansa

Question 5

Posterior approach to carotid was described by

Answer 5

Berguer

Question 6

Posterior approach to carotid exposure steps

Answer 6

1) Prone with contralateral arm under head
2) Transverse incision from Occipital protuberance to mastoid then curve down past boarder of SCM by 2-3 cm
3) Divide greater occipital nerve at dorsal ramus of C2 which course over semispinalis capitis muscle

Question 7

More proximal carotid exposure gained by dividing:

Answer 7

Omohyoid muscle

Question 8

More distal carotid exposure gained by:

Answer 8

1) divide Sternomastoid artery and vein
2) retract vagus and IJ medially
3) Divide digastric sharply to avoid thrermal injury to glossopharyngeal
4) Nasotrachial intubation
5) subluxation of mandible

Question 9

Miniincision for carotid exposure key points

Answer 9

1) two 90 degree retractors
2) bull dogs use deep in wounds
3) skin laxity with undermining

Question 10

Reoperation key points

Answer 10

1) avoide reoperation in 2 years unless > 80% or symptoamtic
2) retrojugular to decrease nerve injury
3) consider interpositional bypass and need to dissect more carotid than initial OR

Question 11

Carotid subclavian transposition steps

Answer 11

1) Supine with roll
2) transverse incision 1 finger above clavicle medial to lateral SCM head for about 6 cm
3) Divide plastysma and superior cervical aponeurosis
4) ligate external jug vein
5) Clavicular head of SCM, either divide or retract
6) divide omohyoid
7) mobilize IJ vein
8) identify thoracic duct and ligate
9) Retract sternal SCM and subhyoid medially
10) divide vertebral vein
11) avoid injury to sympathetic chain medial to vertebral vein around subclavian artery
12) vagus and recurrent laryngeal nerve need to be protected

Question 12

When do you get right sided thoracic duct

Answer 12

People with Aberrant right subclavian artery

Question 13

More proximal exposure for subclavian requires

Answer 13

1) divide medial head of clavicle
2) right medial sternotomy and divide innominate vein
3) left anterior lateral thoracotomy

Question 14

Subclavian bypass exposure

Answer 14

Divide SCM clavicular head

2) scalene fat pad mobilize inferiortly and medially, then retract superior laterally
3) Dissect and protect phrenic nerve
4) divide anterior scalene close to insertion of first rib
5) divide thyrocervical trunk

Question 15

Vertebral artery segment classification

Answer 15

Berguer class
V1: origin to entry at C6
V2: C6-C2
V3: C2 to base of skull before foramen magnum
V4: intracranial: atlanto-occipital membrane to basilar

Question 16

V1 exposure options

Answer 16

1) Supraclavicular

2) anterior cervical

Question 17

Supraclavicular approach to V1 exposure

Answer 17

Only expose proximal vert

1) supine with head turned
2) transverse 1 finger above clavicle for 6-8 cm
3) Divide platisma, superior fascial and external jugular
4) Dissect between SCM heads or divide clavicular head
5) Divide omohyoid
6) Retract IJ vein laterally
7) Identify vagus and retract medially or laterally
8) Divide thoracic duct
9) divide inferior thyroid artery
10) divide vertebral vein

Question 18

Anterior cervical approach to V1 exposure

Answer 18

1) same as CEA
2) vert from clavicular head to retromandibular area
3) divide omohyoid superior belly
4) divide scalene fat pad
5) protect phrenic nerve
6) divide inferior thyroid artery

Question 19

V2 exposure

Answer 19

1) anterior cervicular approach from clavicular head to mastoid process
2) divide plastisma, retract SCM
3) dissect larynx, pharynx and carotid sheath from prevertebral fascial then retract medially
4) incise anterior longitudinal ligament vertically then retract laterally
5) preserve sympathetic ganglia
6) identify prevertebral fascial, longus colli and longus capitis and remove all from the transverse process with periosteal elevator
7) Rongeur out anterior arch of transverse process

Question 20

How to avoid cervical nerve injury in V2 exposure

Answer 20

Do not extent past lateral boarder of the transverse process

Question 21

V3 exposure: why not to operate

Answer 21

1) available endo options
2) fragile vessels
3) surrounded by venous plexus

Question 22

V3 exposure steps

Answer 22

1) Supine or semi sit to decrease venous pressure
2) vertical incision along anterior SCM start at cricoid then curve posteriorly behind earlobe to cross mastoid
3) divide plastysma
4) retract carotid sheath medially and SCM laterally
5) retract accessory nerve anteriorly which enters SCM 2-3 cm below mastoid
6) C1 serves as insertion for levator scapulae, splenius cervicalis and inferior oblique; these cover the C1C2 interspace and need to be ligated

Question 23

V4 exposure

Answer 23

Same as posterior approach for carotids

2) identify IJ vein and accessory nerve
3) divide condyloid emissary vein
4) divide rectus capitis posterior muscle

Question 24

Key in treating carotid body tumours

Answer 24

1) Pre-op embolization reduces bleed
2) send lymph nodes to rule out metastasis
3) tumor is fed from EIA usually branch from bottom of bifurcation
4) ok to sacrifice EIA

Question 25

Vagus nerve position in relation to carotid

Answer 25

Posteriorlateral to ICA

Question 26

Hypoglossus nerve position

Answer 26

Exit skull via hypoglossal canal
Course between IJV and ICA
Cross ECA and ICA 2cm above bifurcation

Question 27

Superior laryngeal nerve position

Answer 27

Posterior to carotid artery usually adjacent to superior thyroid artery

Question 28

Spinal accessory nerve position

Answer 28

Course over distal ICA behind stylohyoid and enters SCM near digastric muscle

Question 29

Glossopharyngeal nerve position

Answer 29

Corss anterior to ICA near digastric muscle

Question 30

Marginal mandibular nerve position

Answer 30

Branch of facial vein –> runs along masseter

Question 31

What instrument can decrease nerve injury in carotid or neck exposures

Answer 31

Bipolar cautery