Smith Robinson Approach

Via the carotid triangle

 

SCM / posterior belly digastric / superior belly omohyoid

 

Indication

 

Exposes inferior body C2 - T1

 

Position

 

1.  Supine in tongs

2.  Sit on head board with head taped and slightly extended

 

Table 30° up

Turn head away from side of incision

 

Which Side

 

Most surgeons approach from the left

- the course of the Recurrent Laryngeal Nerve / RLN is more predictable on left

 

Right sided approach

- used sometimes for C7/T1 to avoid thoracic duct

 

Recurrent Laryngeal Nerve

 

Right side

- given off the vagus at the level of the subclavian artery

- slopes from lateral to medial across lower part of wound to reach the oesophagus / trachea interval

- crosses the surgical approach in 50% of cases

- usually at C6/7

- may be at C5/6

 

Left side

- arises at the level of the aortic arch

- doesn't slope across the wound

 

3 Fascial layers

 

1.  Deep Cervical Fascia

- under the subcutaneous fat

- invests neck like collar

- clavicle / sternum / spine scapula - mandible / base of skull

- invests SCM & trapezius

- Have to incise so can retract SCM

 

2.  Pretracheal

- covers trachea

- deep to the strap muscles

- extends from hyoid into chest

- splits to enclose thyroid

- fuses laterally with carotid sheath

- have to divide to retract carotid sheath laterally

 

3.  Prevertebral

- base of skull to T3

- invests longus colli and sympathetics

- divide to separate longus colli muscles to approach verebrae

 

Landmarks

 

Medial border SCM

Carotid Artery lateral to SCM

 

Levels

- Hyoid = C3

- Thyroid Cartilage = C4/5

- Cricoid = C6

- Carotid Tubercle = C6

 

Incision

 

Inject LA with adrenaline

Transverse incision at level required from midline to posterior border SCM

 

Superficial Dissection

 

Divide Platysma vertically at anterior border SCM

 

Superficial plane

- through investing layer of deep cervical fascia

- between strap muscles (Sternohyoid & Sternothyroid) & anterior border SCM

 

Deep Dissection

 

Palpate the Carotid Artery 

- divide the pretracheal fascia medial to the Carotid Sheath

- open plane between carotid sheath & medial structures

- medially oesphagus, trachea & thyroid

- note that anterior carotid sheath fuses to pretracheal fascia

- retract the carotid sheath & SCM laterally

 

Vessels

 

C3/4

- superior thyroid artery / superior laryngeal nerve behind

- common venous trunk of superior thyroid / lingual / facial vein

 

C6/7

- ligate middle thyroid vein

- inferior thyroid artery

 

Blunt dissection medially

- behind the oesophagus

- expose the vertebrae covered by Longus Colli, prevertebral fascia & ALL

- sympathetic chain lies on the Longus Colli, just lateral to the vertebrae

- incise the Longus Colli in the midline

- subperiosteally expose the Vertebrae

- place retractors under Longus Colli

 

Check level with II

 

Dangers

 

1. Recurrent Laryngeal Nerve

- lies between trachea & oesphagus

- on right crosses field from subclavian artery at C6/7 with inferior thryoid artery

 

2. Superior Thyroid Artery/ Superior Laryngeal Nerve

- C3/4

- superior thyroid artery pass from the Carotid Sheath medially to the midline structures

- superior laryngeal nerve runs with artery

- can divide artery but must preserve nerve

- otherwise get dysphagia

 

3.  Inferior Thyroid Artery

- lower approach may pass from lateral to medial

 

4. Sympathetic Chain on transverse processes

5. Vertebral Artery

6. Carotid Sheath with Vagus inside

7. Oesophagus

8. Trachea

9. Thoracic duct on left at C7 / T1 level