Chapter 55 - Cerebrovascular exposure Flashcards
Carotid exposure steps
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
What are the vascular branches tethering CN XII
SCM branches of occipital artery
Why avoid dissection of ECA far from the bifurcation
Superior laryngeal nerve runs behind it
Retrojugular approach to carotid exposure pro and con
Con: decrease visualization of EIA
Pro: better ICA visualization, no need to divide veins or ansa
Posterior approach to carotid was described by
Berguer
Posterior approach to carotid exposure steps
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
More proximal carotid exposure gained by dividing:
Omohyoid muscle
More distal carotid exposure gained by:
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
Miniincision for carotid exposure key points
1) two 90 degree retractors
2) bull dogs use deep in wounds
3) skin laxity with undermining
Reoperation key points
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
Carotid subclavian transposition steps
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
When do you get right sided thoracic duct
People with Aberrant right subclavian artery
More proximal exposure for subclavian requires
1) divide medial head of clavicle
2) right medial sternotomy and divide innominate vein
3) left anterior lateral thoracotomy
Subclavian bypass exposure
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
Vertebral artery segment classification
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
V1 exposure options
1) Supraclavicular
2) anterior cervical
Supraclavicular approach to V1 exposure
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
Anterior cervical approach to V1 exposure
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
V2 exposure
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
How to avoid cervical nerve injury in V2 exposure
Do not extent past lateral boarder of the transverse process
V3 exposure: why not to operate
1) available endo options
2) fragile vessels
3) surrounded by venous plexus
V3 exposure steps
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
V4 exposure
Same as posterior approach for carotids
2) identify IJ vein and accessory nerve
3) divide condyloid emissary vein
4) divide rectus capitis posterior muscle
Key in treating carotid body tumours
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
Vagus nerve position in relation to carotid
Posteriorlateral to ICA
Hypoglossus nerve position
Exit skull via hypoglossal canal
Course between IJV and ICA
Cross ECA and ICA 2cm above bifurcation
Superior laryngeal nerve position
Posterior to carotid artery usually adjacent to superior thyroid artery
Spinal accessory nerve position
Course over distal ICA behind stylohyoid and enters SCM near digastric muscle
Glossopharyngeal nerve position
Corss anterior to ICA near digastric muscle
Marginal mandibular nerve position
Branch of facial vein –> runs along masseter
What instrument can decrease nerve injury in carotid or neck exposures
Bipolar cautery
