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Updated: Jan 24 2023

Anterior Approach to Cervical Spine

https://upload.orthobullets.com/topic/12001/images/rln.jpg
Indications
  • Overview
    • widely used approach that exposes anterior vertebral bodies from C2 to T1
  • Indications
    • cervical radiculopathy
      • anterior cerical disctomy & fusion (ACDF)
    • myelopathy
      • anterior corpectomy and fusion
    • tumor
      • anterior corpectomy and fusion
    • odontoid fracture
      • C2 anterior screw osteosynthesis
    • infection & epidural abscess
      • anterior cervical discectomy & fusion (ACDF)
Applied surgical anatomy
  • It is important to understand the three fascial layers of the neck
    • superficial fascia
      • formed by the investing layer of deep cervical fascia
      • platysma and external jugular vein are only structures superficial to it
      • surround neck like a collar, but splits around the SCM and trapezius
    • pretracheal fascia
      • continous with carotid sheath at sheath's lateral margin
      • superior and inferior thyroid vessels run from the carotid sheath through the pretracheal fascia to the midline
    • prevertebral fascia
      • thick and tough fascia that lines in front of the prevertebral muscles
      • the cervical sympathetic trunk (runs over transverse processes) runs on its surface
  • Landmarks
    • angle of mandible correlates with the C2-3 disc space 
    • carotid tubercle is the anterior tubercle of the transverse process of C6
Planes
  • Superificial
    • divide platysma which is innervated high up in the neck by the facial (seventh) cranial nerve
  • Middle
    • sternocleidomastoid (spinal accessory nerve)
    • strap muscles (segmental innervation from C1, C2, C3)
  • Deep
    • left longus colli muscles (segmental branches of cervical nerves)
    • right longus colli muscles
Preparation
  • Anesthesia
    • general as airway needs to be protected
  • Position 
    • supine
  • Imaging
    • cross table lateral required to identify correct level
      • shoulders/arms often pulled caudal to obtain better visualization of C7
Approach
  • Incision
    • make transverse skin crease incision at appropriate level
    • extend obliquely from the midline to the posterior border of the SCN
    • side
      • surgeons preference
  • Superficial Dissection
    • incise fascia over platysma
    • spit platysma with finger
    • identify anterior border of SCM
    • incise fascia and retract SCM lateral
    • identify and retract strap muscles medially (sternohyoid and sternothyroid)
    • identify the carotid pulse and retract carotid sheath lateral
    • cut through pretrachial fascia
    • localize superior and inferior thyroid arteries and tie off if necessary
  • Deep dissection
    • split longus colli muscles and anterior longitudinal ligament
      • be aware of sympathetic chain that lies on longus colli lateral to vertebral body
    • subperiostally disect to expose anterior surface of vertebral body
      • retract longus colli muscles and ALL laterally
    • identify level with needle in disc space and lateral xray
Structures at Risk
  • Recurrent laryngeal nerve
    • injury rate 2.3% (same injury rate for left RLN and right RLN)
    • left RLN
      • ascends in neck in tracheoesophageal groove after branching off from parent nerve the vagus at the level of the arch of the aorta  
    • right RLN
      • runs alongside the trachea in the neck after hooking around the right subclavian artery
      • crosses from lateral to medial to reach midline
      • more vulnerable than left during exposure because
        • it has a more variable course
        • lies more anterolateral
    • protect by placing retractors under medial edge of longus colli muscle
  • Sympathetic nerves and stellate ganglion
    • damage or irritation causes Horner's syndrome 
      • characterized by ptosis, anhydrosis, miosis, enophthalmos and loss of ciliospinal reflex on the affected side of the face
      • caused by injury to sympathetic chain, which sits on the lateral border of the longus colli muscle at C6
    • protect by subperiosteal dissection of longus colli muscles from midline
  • Carotid sheath and contents
    • protected by the anterior border of SCM
    • be careful with lateral retractor placement
  • Postoperative retropharyngeal hematoma
    • presents with respiratory difficulties
    • tense hematomas should be emergently decompressed if causing respiratory compromise
      • physical exam will show a tense mass under the incision
    • most common cause is postsurgical edema
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