Anterior Approach to the Cervical Spine ‌

The anterior approach to the cervical spine exposes the anterior vertebral bodies from C3 to T1. It also allows direct access to the disc spaces and uncinate processes in the region. It is used for the following:

1. Excision of herniated discs (R.B. Cloward, personal communication, 1969)21

2. Interbody fusion (see the section regarding the anterior approach to the iliac crest for bone graft)

3. Removal of osteophytes from the uncinate processes and from either the

   anterior or the posterior lip of the vertebral bodies

4. Excision of tumors and associated bone grafting

5. Treatment of osteomyelitis

6. Biopsy of vertebral bodies and disc spaces

7. Drainage of abscesses

8. Open reduction and internal fixation of fractures

The recurrent laryngeal nerve is the most important structure at risk during the anterior approach to the cervical spine. The left recurrent laryngeal nerve ascends in the neck between the trachea and the esophagus, having branched off from its parent nerve, the vagus, at the level of the arch of the aorta. The right recurrent laryngeal nerve runs alongside the trachea in the neck after hooking around the right subclavian artery. In the lower part of the neck, it crosses from lateral to medial to reach the midline trachea; therefore, it is slightly more vulnerable during the exposure than is the left recurrent laryngeal nerve. This is why some surgeons prefer left-sided approaches, whereas others simply approach from the side of pathology.

Position of the Patient

Place the patient supine on the operating table with a small sandbag or roll between the shoulder blades to ensure extension of the neck. Turn the patient’s head away from the planned incision to provide good access to the side of the neck (Fig. 6-70). Some cases may require application of halter traction so that it can be used later if distraction is required. Elevate the table 30 degrees to reduce venous bleeding and make the neck more accessible. Place the patient’s arm at his or her side after careful padding.

Figure 6-70 Place the patient supine on the operating table with a small sandbag between the shoulder blades to ensure an extended position of the neck. Turn the patient’s head away from the planned incision.

Landmarks and Incision

Landmarks

Several palpable or visible anterior structures in the midline help identify the vertebral level in the neck.

1. Hard palate—arch of the atlas

2. Lower border of the mandible—C2-3

3. Hyoid bone—C3

4. Thyroid cartilage—C4-5

5. Cricoid cartilage—C6

6. Carotid tubercle—C6

These landmarks make it possible to determine the approximate level of the incision (Fig. 6-71; see Fig. 6-82) and this should be confirmed radiologically.

Sternocleidomastoid Muscle. The sternocleidomastoid, an oblique

muscle, runs from the mastoid process to the sternum, just lateral to the midline of the neck. To make it more prominent, turn the head away from the muscle in question, into the operating position.

Carotid Artery. Place a finger over the leading edge of the sternocleidomastoid and press posteriorly and laterally to feel the carotid pulse.

Carotid Tubercle (Chassaignac Tubercle). Palpate deeper; note the large tubercle adjacent to the carotid pulse on the anterior part of the transverse process of C6.22

Incision

If the level of pathology is localized, make a transverse skin crease incision at the appropriate level of the vertebral pathology (see above). The incision should extend obliquely from the midline to the posterior border of the sternocleidomastoid muscle. Such an incision has extreme cosmetic advantage (see Fig. 6-71).

Internervous Plane

No internervous plane is available superficially, but incising or dividing the platysma muscle causes no significant problems; the muscle is supplied high up in the neck by branches of the facial (seventh cranial) nerve.

More deeply, the plane lies between the sternocleidomastoid muscle (which is supplied by the spinal accessory nerve) and the strap muscles of the neck (which receive segmental innervation from C1, C2, and C3; see Fig. 6-74, cross section).

Figure 6-71 Make an oblique incision in the skin crease of the neck at the appropriate level of the vertebral pathology.

Figure 6-72 Incise the fascial sheath over the platysma in line with the skin incision. Split the platysma longitudinally, parallel to its long fibers.

Deeper still, the plane lies between the left and right longus colli muscles, which are supplied separately by segmental branches from the second to the seventh cervical nerves (see Fig. 6-76, cross section).

Superficial Surgical Dissection

The skin and the platysma muscle are very vascular. For this reason, some surgeons inject the area with a dilute solution of epinephrine (Adrenalin) before incising the skin.

Incise the fascial sheath over the platysma in line with the skin wound (Fig. 6-72). Then, split the platysma longitudinally using the tips of the index fingers, dissecting parallel to the long fibers. The platysma fibers can also be divided with a knife. Identify the anterior border of the sternocleidomastoid muscle and incise the fascia immediately anterior to it (Fig. 6-73). Using the fingers, gently retract the sternocleidomastoid muscle laterally. Retract the sternohyoid and sternothyroid strap muscles (with the associated trachea and underlying esophagus) medially.

Figure 6-73 Identify the anterior border of the sternocleidomastoid and incise the fascia medially anterior to it.

The carotid sheath enclosing the common carotid artery, vein, and vagus nerve now can be exposed, if necessary (Fig. 6-74).

Palpate the artery. Develop a plane between the medial edge of the carotid sheath and the midline structures (thyroid gland, trachea, and esophagus), cutting through the pretracheal fascia on the medial side of the carotid sheath. Retract the sheath and its enclosed structures laterally with the sternocleidomastoid muscle (Fig. 6-75).

Two arteries connect the carotid sheath with the midline structures. These two vessels, the superior and inferior thyroid arteries, may limit the extent to which this plane can be opened up above C3-4. Occasionally, either or both of them may have to be ligated and divided to open the plane.

Now, develop a plane deep to the cut pretracheal fascia by blunt dissection, proceeding carefully in a medial direction behind the esophagus, which is retracted from the midline.

Figure 6-74 Retract the sternocleidomastoid laterally, and the strap muscles and thyroid structures medially. Cut through the exposed pretracheal fascia on the

medial side of the carotid sheath. The cervical spine C3 through C5 (cross section). Retract the sternocleidomastoid laterally and the strap muscles medially, and incise the pretracheal fascia immediately medial to the carotid sheath.

Figure 6-75 Retract the sternocleidomastoid and the carotid sheath laterally, and

the strap muscles, trachea, and esophagus medially to expose the longus colli muscle and prevertebral fascia. Retract the sternocleidomastoid muscle and carotid sheath laterally, and the strap muscles and thyroid structures medially, then split the longus colli muscle longitudinally in the midline (cross section).

Figure 6-76 Dissect the longus colli muscle subperiosteally from the anterior portion of the vertebral body and retract each portion laterally to expose the anterior surface of the vertebral body. The longus colli muscles are retracted to the left and right of the midline to expose the anterior surface of the vertebral body (cross section).

The cervical vertebrae should be visible now, covered by the longus colli muscle and the prevertebral fascia. The anterior longitudinal ligament in the midline can be seen as a gleaming white structure. The sympathetic chain lies on the longus colli, just lateral to the vertebral bodies (see Fig. 6-77).

Deep Surgical Dissection

Using cautery, split the longus colli muscle longitudinally over the midline of the vertebral bodies that need to be exposed (see Fig. 6-75, cross section). Then, dissect the muscle subperiosteally with the anterior longitudinal ligament and retract each portion laterally (i.e., to the left and right of the midline) to expose the anterior surface of the vertebral body (Fig. 6-76). Obtain a lateral radiograph after placing a needle marker in the appropriate vertebral body to identify the level correctly. Make sure that the retractors are placed underneath each of the longus colli muscles, widening the exposure while protecting the recurrent laryngeal nerve, trachea, and esophagus.

Dang

Nerves

The recurrent laryngeal nerve may be traumatized during the deepest layer of the approach. Protect it by placing the retractors well under the medial edge of the longus colli muscle (Fig. 6-79).

The sympathetic nerves and stellate ganglion may be damaged or irritated, causing Horner syndrome. Protect them by making sure that dissection onto the bone is subperiosteal from the midline.

Avoid dissecting out onto the transverse processes (Fig. 6-80; see Fig.

6-75).

Vessels

The carotid sheath and its contents are protected by the anterior border of the sternocleidomastoid muscle. Do not place self-retaining retractors in

this area, or the sheath will be endangered. If additional retraction is necessary, use hand-held retractors with rounded ends (see Figs. 6-74, cross section, and 6-79).

The vertebral artery, which lies in the transverse foramen on the lateral portion of the transverse processes, should not be visible during the approach unless the plane of operation strays well away from the midline (Fig. 6-81; see Fig. 6-76, cross section).

The inferior thyroid artery may cross the operative field in lower cervical approaches. If it is divided accidentally, it may retract behind the carotid sheath, where it is difficult to retrieve and tie off (see Fig. 6-80).

Special Points

Poorly placed retractors endanger the trachea and esophagus. Unless they are placed underneath the longus colli muscle, the retractors used should be rounded and hand-held (see Fig. 6-76, cross section).

How to Enlarge the Approach

Local Measures

To enlarge the approach laterally, remove the origins of the longus colli muscle subperiosteally from the vertebral body. Take care not to proceed too far laterally to avoid damaging the sympathetic chain.

Extensile Measures

This approach cannot be extended.