Midline Dorsal Approach

Either the sitting or the prone position can be used in a midline dorsal approach. If skull traction is required, the prone position with a horseshoe attachment should be considered (Figs. 169-7 and 169-8).

FIGURE 169-7 Dorsal midline cervical approach with horseshoe head holder and skeletal traction.

FIGURE 169-8 Two different fixation devices for dorsal cervical operations: horseshoe head holder (A) and Mayfield-type head clamp with three pins (B).

The dorsal scalp and cervical regions are prepared for incision. If a fusion is planned, the area for the bone harvest (usually the dorsal iliac crest) should also be prepared. A midline incision is made from the external occipital protuberance to the midcervical spinous processes (C5 or C6 or the most appropriate level). Avoid unnecessary dissection, especially of the interspine and ligaments.

Two deep-seated self-retaining retractors are usually satisfactory. Menezes recommends using two retractors placed at 90 degrees to each other to prevent motion of the occipitocervical and atlantoaxial joints.³

Lateral Transcondylar Approach

The lateral transcondylar approach is also termed the extreme lateral transcondylar approach or the far lateral approach. With this approach, it is possible to reach the lower clivus, the ventral foramen magnum, and the craniovertebral junction without significant retraction of the lower brainstem, the cervical spinal cord, or the cerebellum.

The sitting, lateral park-bench, or prone position may be used. In the prone position, the head should be turned to the side of the lesion (at least 20 degrees), and a rigid three-pin head holder should be used. The sitting position provides an excellent exposure, but it carries the risk of air embolism.

The lateral position is a viable option, because the cerebellum falls away from the operating site and venous drainage is optimized. If a modified park-bench position is preferred, the head is rotated downward, flexed, and tilted away from the shoulder.

A straight dorsolateral incision may be used, although an inverted J-shaped incision is preferred (Fig. 169-9). This incision begins at the mastoid process, extends rostrally and medially, and then extends caudally in the midline to the level of C6. Because the occipital muscles cover the craniectomy after the use of an inverted J-shaped incision (compared with a linear incision placed over a craniectomy), this incision is useful in preventing postoperative cerebrospinal fluid leakage.

FIGURE 169-9 Various incisions used for dorsolateral transcondylar approach: inverted J-shaped incision (red line), midline dorsal incision (dashed line), and dorsolateral incision (dotted line).

Hooks are useful for retracting the bulky cervical musculature. A self-retaining cerebellar retractor works well.

One of the most difficult aspects of this operation is the development of a dissection plane along the lateral aspect of C1 and C2 without causing injury to the vertebral artery or associated venous structures.

To avoid the introduction of occipitocervical instability, it is recommended not to remove more than one half of the occipital condyle. The roots of C2 may be sectioned. Only a slight retraction of the vertebral artery, if any, is usually necessary. The cerebellum and the brainstem should not be retracted.

Salas et al.⁴ have defined four varieties of dorsolateral craniocervical approaches. The transfacetal approach is used to treat extradural and intradural lesions ventral to the upper cervical spinal cord. The retrocondylar approach is performed for intradural lesions that are located predominantly lateral or ventrolateral to the spinomedullary region or to expose the extradural portion of the vertebral artery. The partial transcondylar approach is performed to treat lesions that are located predominantly ventral to the spinomedullary junction. The complete transcondylar approach is performed to treat extradural lesions. The extreme lateral transjugular approach is performed to supplement the traditional lateral transtemporal approach for the treatment of jugular foramen lesions.

Transoral Approach

A standard placement is to have the surgeon at the side and the anesthetic equipment and anesthetist at the head of the patient. Alternatively, the anesthetic equipment may be placed at the foot, and the surgeon may be at the head of the patient. The patient is positioned supine, and intubation is performed with a small endotracheal tube, which is securely fastened. Intubation when the patent is awake may be necessary if the spine is unstable. Slight extension facilitates the approach.

Although tracheotomy is not routinely used, an elective tracheotomy should be considered if the mouth does not allow adequate space for an endotracheal tube within the operating field.

Because the predominant difficulty with the transoral approach is the depth and narrowness of the operative field, a self-retaining retractor is imperative. Retraction of the uvula is also frequently necessary (see Fig. 169-3).

The soft palate may be held away from the surgical trajectory by a retractor or by suturing its border with the uvula to the dorsal palate. Alternatively, a rubber catheter may be passed through the nose and into the mouth. The distal tip of the catheter is sutured to the uvula, and upward traction is applied by gently pulling the catheter through the nose.

An incision is made in the midline of the dorsal pharynx after infiltration with a local anesthetic containing epinephrine to decrease oozing from the pharyngeal walls. The incision is carried along the tubercle of the atlas to the prominence of the C2-3 disc space. The incision may be extended, if needed, onto the soft palate and to one side of the uvula.

After dissection of the ventral surfaces of the atlas and axis laterally, a second self-retaining retractor is held to open the dorsal pharyngeal wall along the long axis of the spine. Stay sutures may be used to provide lateral retraction (see Fig. 169-1).

This surgery is relatively straightforward. Once the pharyngeal mucosa and prevertebral muscles have been cleared away, this approach offers an excellent view of the upper ventral cervical spine, which is relatively avascular.

Median Labiomandibular Glossotomy

Median labiomandibular glossotomy provides a wide ventral exposure from the clivus to the lower cervical spine.^5–7 A midline vertical incision starts from the lower lip, extends caudally, turns around the chin prominence, and again passes medially in the neck (Fig. 169-10). The mandible is cut in a stepwise configuration for subsequent approximation. The tongue is incised longitudinally from the central raphe, and the oropharyngeal mucosa is incised laterally.

FIGURE 169-10 Mandible-splitting ventral approach to the upper cervical spine: incision line (A) and retraction and exposure following mandible and tongue splitting (B).

When the mandible, mucosa, and tongue are divided, all the medial structures may be retracted laterally, and the dorsal structures, such as the epiglottis and the dorsal pharynx, are visualized.

Because of high morbidity rates, this technique is preferred mostly in cases with primary malignant or aggressive benign tumors.⁸

Bilateral Sagittal Split Mandibular Osteotomies

This approach is performed in orthognathic surgery to repair a variety of facial and jaw deformities. Because all the incisions that are made in this approach are intraoral, they are not associated with the cosmetic deformities.⁹ It is an adjunct to the transoral approach, and the retraction plane is rostrocaudal instead of lateral. Lingual or inferior alveolar nerve injuries are common complications.

Transthyroid Approach

The transthyroid approach may provide access to the first four cervical vertebrae.¹⁰ A transverse incision is carried along the upper neck crease, between the hyoid bone and the thyroid cartilage, and is extended laterally (Fig. 169-11). The platysma and sternohyoid muscles are divided, and the thyrohyoid membrane is detached from the hyoid bone while the epiglottis is protected.

FIGURE 169-11 Incision line for transthyroid approach.

The internal laryngeal nerves are protected, and the ventral pharynx is entered. Rostral retraction of the hyoid bone and caudal retraction of the thyroid cartilage are performed. After incision of the dorsal pharyngeal wall, a self-retaining retractor exposes the vertebral bodies from C1 to C4. Because of the potential for significant morbidity, this approach is used infrequently. It has been associated with damage to the superior and internal laryngeal nerves and involves a significant risk of damaging the epiglottis.¹⁰

Ventrolateral Retropharyngeal Approach

The ventral retropharyngeal approach provides access to structures from the clivus to the third cervical vertebrae without entering the oral cavity.^3,11–14 The advantages of this approach are lowered risks of infection and more extensive exposure of the upper cervical spine.

The patient is positioned supine, and if the incision is on the right side, the head is turned to the left. Moderate extension of the head facilitates the approach to the upper cervical structures.

The upper transverse portion of a T-shaped incision is made just under the mandible. The vertical portion of the incision meets the sternocleidomastoid muscle caudally (Fig. 169-12A). Another option is a V-shaped incision (Fig. 169-12B).¹³

FIGURE 169-12 Incision lines used for ventral upper cervical approaches. Ventromedial retropharyngeal approaches: T-shaped incision of Schoerbringer (A); incision of Riley (B). Ventrolateral approach: incision of Whitesides (C).

This ventral retropharyngeal approach may be called retrovascular or prevascular surgery (Fig. 169-13).¹⁵ Prevascular surgery involves an access medial to the carotid sheath and traverses the same fascial planes as in the ventrolateral lower cervical spine surgery¹² (see Fig. 169-13B). It allows adequate spinal cord decompression up to the clivus and reconstruction of the anterior column of the spine with strut grafts and internal fixation.

FIGURE 169-13 A, Ventromedial retropharyngeal approach may be accomplished by two different approaches. B, The prevascular route is taken medial to the carotid artery and internal jugular vein. C, Retrovascular surgery is performed lateral to these vascular structures.

(Redrawn from Laus M, Pignatti G, Malaguti MC, et al: Anterior extraoral surgery to the upper cervical spine. Spine [Phila Pa 1976] 21:1687–1693, 1996.)

The dissection is medial to the sternocleidomastoid muscle and the carotid artery. The submandibular gland may be resected. The facial, lingual, hypoglossal, and superior laryngeal nerves should be identified and protected. After rostral and lateral retraction of these nerves, the hyoid bone and hypopharynx may be retracted medially.

After the platysma muscle is incised, the inferior division of the facial nerve and submandibular gland may be divided. The carotid sheath is identified and protected. The dorsal belly of the digastric muscle is traced and transected near its tendon. To retract the larynx, the stylohyoid muscle is transected. The hypoglossal nerve is identified and protected. The retropharyngeal space is opened and bluntly dissected. After retraction of the longus colli muscles, a self-retaining retractor is positioned.^1,13 It may be difficult to place a self-retaining retractor in this opening. A table-mounted system may be useful in this region.

Lateral Cervical Approach

Some authors refer to the lateral cervical approach as a retrovascular variant of the ventral retropharyngeal approach.¹² It is an anatomically complex access that requires sternocleidomastoid muscle eversion; exposition of the spinal accessory nerve and medial mobilization of the jugular vein, vagus nerve, carotid artery, vertebral artery, and cranial nerves XII, IX, VII¹⁶ (Fig. 169-14). Although it provides a true lateral access to the upper cervical spine, only limited access is obtained, and neither grafting nor extensive bony decompression can be achieved. It is also noted to have a significant association with vertebral artery damage.¹⁷

FIGURE 169-14 Incision lines used for ventral approaches to the midcervical and lower cervical spine. Straight lines are for transverse incision at different levels; the oblique dashed line is the longitudinal incision parallel to the sternocleidomastoid muscle; the oblique small dashed line is a curvilinear incision for wider exposure of the multisegmental disease.

The major difference between a ventrolateral retropharyngeal approach and a straight ventral retropharyngeal approach is that the exposure is lateral to the carotid sheath.^14,17,18

The supine or lateral position is used. The neck is extended, and the head is turned maximally. Skeletal traction or a three-point head fixator may be used.

A hockey-stick incision is fashioned along the ventral border of the sternocleidomastoid muscle. The incision begins behind the ear, proceeds caudally over the mastoid process, and extends below the mandibular angle toward the midline (Fig. 169-12C).

The external jugular vein is ligated and divided. The sternocleidomastoid muscle is divided transversely below the mastoid process. The occipital artery is also ligated. The greater auricular and accessory nerves are identified and protected. A dissection plane is developed dorsal to the carotid sheath and the retropharyngeal space.¹⁶

This approach may be fashioned for primary tumors of the upper cervical spine (Fig. 169-15).

FIGURE 169-15 An osteochondroma of the C2 body (A–C) is removed totally by a lateral cervical approach and an incision line turned around the previous biopsy incision (D–F).

Laminectomy and Laminoplasty

The patient position for a midline dorsal cervical approach is similar to that used for posterior fossa approaches. Either the sitting position or a prone position may be used.

A longitudinal midline incision is centered over the vertebrae of interest. The occipital ridge must be exposed for occipital fusions.

A bilateral subperiosteal dissection is performed over the laminae with sharp elevators or electrocautery. If no fusion is anticipated, the facet capsules should be preserved. Avoid injury to supraspinous ligaments. To avoid postoperative swelling and excessive injury to the erector spinae muscles, self-retaining retractors should be released periodically.

To decrease the blood loss, packing with sponges may be helpful. Also, the dorsal branches of the segmental arteries that emerge lateral to the facet joints should be preserved to avoid excessive bleeding.

Laminoforaminotomy for Cervical Disc Disease

In laminoforaminotomy for cervical disc disease, three different positions may be used: the prone position, the sitting position, and the lateral or park-bench position.¹⁹ Because lateral muscle retraction is necessary for exposure, hyperflexion and hyperextension should be avoided. If the spine is hyperflexed, the tightened muscles and tendons make lateral retraction difficult. If the spine is hyperextended, the interlaminar spaces close, and interlaminar exposure is difficult.¹⁹

A midline dorsal or paramedian dorsal incision may be used. The dorsal paramedian incision is used only for single-level laminoforaminotomy.¹⁹ This is a muscle-splitting approach, with only dissection of the muscles from the lamina and facet surfaces. This approach may be used for the keyhole foraminotomy.²⁰

The classical midline dorsal approach requires the resection of the muscle attachments from the spinous processes to expose the facets and laminae.²¹ Only strong lateral retraction is needed to retract the muscles.

Ventromedial Approach

Exposure of the disc space and vertebral body is usually accomplished by a ventromedial approach.^22–25 The patient is positioned supine with the head and neck neutral or slightly extended. Extension of the upper cervical region, with chin retraction, is helpful to reach the C2-3 level. Extension of the midlower cervical region is helpful to reach the high thoracic region. The head is turned away from the surgeon. In the setting of severe cervical stenosis, extreme extension of the cervical spine may cause spinal cord damage and therefore should be avoided.

The sternocleidomastoid muscle is the surface incision landmark for the ventral approach. Either a transverse or a longitudinal incision is appropriate (see Fig. 169-14). Rengachary²⁶ suggests a longitudinal incision for patients with a short neck and kyphotic deformity. The incision begins below the angle of the mandible, extends forward toward the hyoid bone, extends caudally over the sternocleidomastoid muscle, and terminates in the suprasternal notch (see Fig. 169-14).²⁶

A transverse incision may be used for patients with short necks and limited pathology, whereas a longitudinal incision parallel to the sternocleidomastoid muscle may be used for long thin necks with more extensive pathology. Right-handed surgeons may prefer to use right-sided incisions, although it is usually optimal to approach the patient from the side opposite the most prominent pathology. After the incision of the platysma muscle, the sternocleidomastoid muscle is freed from its attachments.

The carotid sheath is easily identified under the muscle. Both may be retracted laterally by the surgeon’s fingers (Fig. 169-16A). Rostrally, the 12th cranial nerve and, caudally, the recurrent laryngeal nerve should be avoided. Other structures that cross the wound transversely may be sacrificed if necessary. These include the inferior and superior thyroid veins and arteries, the facial veins, and the inferior belly of the omohyoid muscle. Injury to the superior laryngeal and superior thyroid artery should be avoided.

FIGURE 169-16 Three basic ventral approaches to the midcervical and lower cervical spine: ventral-medial approach (A); ventral-lateral approach, medial to the sternocleidomastoid muscle (B); and ventral-lateral approach, lateral to the sternocleidomastoid muscle and great vessels (C).

The three main retraction systems that are available for ventral cervical surgery are hand-held retractors, self-retaining retractors, and table-fixed retractors (see Fig. 169-4). Saunders¹⁶ prefers a table-fixed retraction system for both the ventromedial and ventrolateral approaches. Retractors themselves may cause injury to the lateral structures, such as the carotid artery, internal jugular vein, cranial nerves 10 and 12, nerve roots, sympathetic chain, thoracic duct, and lung apex. The medial structures, such as the esophagus and the trachea, are also at risk. Manual retraction is usually used at the beginning of the dissection until the deep cervical fascia is opened and the longus colli muscles are visualized.

Soft tissue structures may be placed under significant tension with a self-retaining retractor. The positioning of the medial blades is particularly important. The most common retraction injury is caused by medial retraction of the esophagus; therefore, the retractor blade should be placed under the longus colli muscles. Careful attention must also be given to lateral retraction, which may cause compression of the carotid artery. The ipsilateral superficial temporal artery may be palpated by the anesthesiologist after placement of the retractor to assist with detection of occlusion of the carotid artery. It is prudent to relax the retraction hourly. If necessary, rostral and caudal retraction with blunt-tipped blades may be used.

Ventrolateral Approach

The lateral approach to the cervical spine from C3 to C7 can be performed via a ventrolateral exposure. However, the lateral exposure of C1 and C2 can only be performed with the dorsolateral transcondylar approach.²⁷

The ventrolateral approach has two variations. The trajectory of one approach is medial to the carotid artery, whereas the trajectory of the other is lateral (Figs. 169-16B and C). In the latter approach, the sternocleidomastoid muscle is retracted medially with the carotid sheath. Therefore, retraction of the recurrent laryngeal nerve is avoided.

With either variation, the lateral retractor blade is positioned just lateral to the tubercle of the transverse process, and the medial retractor blade is positioned just medial to the uncinate process (see Figs. 169-16B and C). This exposes the ipsilateral longus colli muscle, which, together with the sympathetic chain, is mobilized medially. The muscle insertions to the transverse process are divided. Positioning and incision are the same in the ventrolateral approach as in the ventromedial approach.

For retraction, a medial exposure is made with blunt dissection. The tubercle of the transverse process is then palpated laterally. This tubercle is approximately 1 cm lateral to the foramen transversarium. Blunt dissection of the common carotid artery and jugular vein is carefully performed to allow retraction of these structures medially. Extreme care should be taken not to injure the vertebral artery or the sympathetic chain.

A ventrolateral approach medial to the carotid sheath is most frequently used to expose the vertebral artery and the nerve root foramen.^28,29 It is essentially a medial approach without midline exposure.^29,30 The carotid sheath is retracted laterally as with the ventromedial approach.

Decompression of lateral cervical disc herniations may be done via the same route. This approach may be termed the ventral cervical foraininotomy,³¹ ventrolateral transpedicular foraminotomy,¹ or microsurgical ventral cervical foraminotomy-uncinatectomy.³² The colli muscles are mobilized, allowing dissection around the lateral aspect of the vertebral body; a retractor between the vertebral body and the vertebral artery is placed; and the lateral portion of the uncovertebral joint is drilled. The herniated disc and uncovertebral osteophytes are removed to decompress the exiting nerve root (Fig. 169-17).

FIGURE 169-17 Ventral cervical foraminotomy-uncinatectomy and the amount of bone to be removed.

A ventrolateral approach lateral to the carotid sheath and sternocleidomastoid muscle is also termed the oblique cervical approach³³ With this exposure, the incision may be fashioned lateral to the sternocleidomastoid muscle. Positioning is similar to that in the ventromedial approach. The head and neck may be slightly turned to the contralateral side. Both the sternocleidomastoid muscle and the great vessels are retracted medially, together with the trachea and the esophagus. A self-retaining retractor may be used, with care taken that the lateral blades do not cause severe retraction of the nerve roots.^33,34

Oblique corpectomy is an effective alternative to other ventral cervical decompressions with advantages of no need for a graft or plate (Fig. 169-18).^33,35

FIGURE 169-18 A 66-year-old man with quadriparesis had an oblique corpectomy at two levels: C4 and C5. Preoperative (A–C) and postoperative (D–F) MRIs show an effective ventral decompression.

Lower Ventromedial Cervical Approach

The lower ventromedial cervical approach is indistinguishable from that used in the midcervical to lower cervical spine.³⁶

Transsternal Approach

The transsternal approach provides a direct ventral route through a median sternotomy.³⁷ The morbidity and mortality are high. Hodgson and Yau³⁸ have reported a 40% mortality rate. Furthermore, this approach provides little advantage over the transmanubrial approach because the soft tissue structures are the predominant limiting factors.

Transmanubrial Approach

The transmanubrial approach is a variation of the transsternal approach.³⁹ It is performed by using an osteotomy of the manubrium, with or without a medial claviculotomy.^38–42 Sundaresan et al.⁴³ recommend resection of the medial third of the clavicle along with the creation of a window in the manubrium (Fig. 169-19).

FIGURE 169-19 A, Transmanubrial exposure. B, Resection of the manubrium and the medial part of the clavicle.

The head is positioned slightly contralaterally in the supine position. Most authors recommend a left-sided approach.

Either of two incisions may be used: a T-shaped incision, with the transverse arm 2 cm above the clavicle and the midline vertical arm extending to the sternum, or a medial sternocleidomastoid incision extending to the sternum.^38,44 This incision permits a simultaneous ventromedial midcervical approach (Fig. 169-20).

FIGURE 169-20 Incisions for ventral cervicothoracic approaches: a, T-shaped incision; b, ventromedial sternotomy incision; c, supraclavicular incision.

The upper outer corner of the manubrium, the first costal cartilage, and the medial third of the clavicle are divided. With this exposure, the great vessels and the lower roots of the brachial plexus are retracted. If it is connected to a ventromedial cervical exposure, a generous exposure to the cervicothoracic vertebrae from C3 to T5 can be obtained.⁴⁵

The sternocleidomastoid muscle and the omohyoid muscle are divided. The phrenic nerve, the 11th cranial nerve, the sympathetic chain, and, on the left side, the thoracic duct should be protected. If necessary, the left innominate vein may be divided.⁴⁴

The manubrium and the clavicle may be reattached by using wires or miniplates. These bone fragments may be used as bone grafts without significant deformity or instability in a tumor patient. In a young healthy individual, the clavicle should be replaced.

Transverse Supraclavicular Approach

The transverse supraclavicular approach was originally described as an exposure for upper thoracic sympathectomy.⁴⁶ A transverse incision parallel to the clavicle and extending beyond the lateral border of the sternocleidomastoid muscle is used.^18,42,47 The sternocleidomastoid muscle, the omohyoid muscle, and the strap muscles are divided. The carotid sheath, the internal jugular vein, and the phrenic nerve are identified and protected. Medial retraction of the neurovascular structures provides a limited exposure lateral to the C7 vertebral body.

Transclavicular Approach

The transclavicular approach (splitting the clavicle) provides an adequate access to the cervicothoracic junction. This approach is most useful for cervicothoracic spine tumors with paravertebral-plexus involvement. Dividing the clavicle assists in the separation of the intrathoracic components from the lung. A zigzag-shaped incision over the clavicle may be used⁴⁸ (Fig. 169-21).

FIGURE 169-21 A zigzag-shaped incision for transclavicular approach to cervicothoracic spine tumors with paravertebral-plexus involvement.

(Redrawn from Kuho T, Nakamura H, Yamano Y: Transclavicular approach for a large dumbbell tumor in the cervicothoracic junction. J Spinal Disord 14:79–83, 2001.)

Transaxillary Extrapleural Approach

The transaxillary extrapleural approach is a high thoracic variant of the transthoracic approach. Its advantage lies in the preservation of the pectoral and shoulder girdle muscles.²⁰ Its disadvantage is that it places the brachial plexus at risk for retraction and stretch injury.

A 60-degree semilateral position is used, with the ipsilateral shoulder and arm abducted. The arm may be fixed in a sling.

A transverse incision is made from the border of the pectoralis muscle to the border of the latissimus dorsi muscle. The third rib is resected, and the dissection is carried through the third rib bed.^39,47,49,50 Retraction is essentially an extrapleural approach. With blunt dissection, the apex of the lung is retracted caudally. A self-retaining retractor may be used.

Lateral Parascapular Extrapleural Approach

With this approach, the parascapular shoulder muscles are reflected off the spinous processes to the scapula with preservation of neurovascular structure.⁵¹ The upper dorsal ribs are removed, the rami communicantes of C8 and T1 are transected, and the sympathetic chain is displaced ventrolaterally. This approach provides easy access to the T2-4 vertebrae.⁵¹

Transpleural Transthoracic Approach

With the transpleural transthoracic approach, the upper thoracic vertebrae can be adequately approached through the fourth rib.⁵² The left-side-up position is preferred, because it is easier to mobilize the aorta than the vena cava. In the event of vascular injury, it is also easier to repair the aorta than the vena cava. It may be preferred over the extrapleural method, because lung retraction is easier. Unlike the extrapleural approach, however, a tube thoracostomy is required.

Segmental vessels are ligated two levels above and below the level of pathology. This allows retraction of the great vessels.

Trapdoor Approach

With the trapdoor approach, a partial median sternotomy and a ventrolateral approach are added to a standard ventral approach to the cervical spine along the medial border of the sternocleidomastoid muscle.⁵³ The sternoclavicular joint and clavicle itself are preserved. It provides a bilateral ventral approach from C4 to T3. Although it provides a wide exposure and proximal control of important vessels, it has a very high morbidity rate (Fig. 169-22).

FIGURE 169-22 Trapdoor approach used for extensive cervicothoracic tumors.

(Redrawn from Nazzaro JM, Arbit E, Burt M: Trap door exposure of the cervicothoracic junction: technical note. J Neurosurg 80:338–341, 1994.)

Thoracic Laminectomy

The patient is positioned prone on a chest frame or on laminectomy rolls that allow the abdominal contents to be free of pressure, thereby reducing venous compression and decreasing blood loss during surgery. Both the pelvis and the knees are flexed to enhance the normal thoracic kyphosis (Fig. 169-23). Specialty tables and frames may be used to minimize abdominal pressure. These tables may also facilitate intraoperative radiography.

FIGURE 169-23 Prone position used for most thoracic, lumbar, and sacral dorsal approaches.

If an upper thoracic spine exposure is desired, the head should be fixed in the neutral position with either a Mayfield head holder or a horseshoe head holder. The patient’s arms are positioned at the side.

If a midthoracic or lower thoracic spine exposure is desired, head fixation is not necessary, and the patient’s arms may be fixed above the head. To avoid causing a brachial plexus stretch injury, care should be taken to not abduct the arms more than 90 degrees.

A few surgeons advocate the lateral position for thoracic laminectomy. This may be particularly useful in the obese patient. A dorsal midline incision is used (Fig. 169-24A).

FIGURE 169-24 Different skin incisions for dorsolateral exposures of the thoracic and lumbar spine: Dorsal midline incision (A), semilunar incision (B), hockey-stick incision (C), straight paramedian incision (D), and T-shaped incision (E).

Several self-retaining retractors with blades of varying widths and depths are available (e.g., Weitlaner retractor, crank-type retractor, cerebellar retractor). Hemilaminectomy retractors and table-mounted retractors are also helpful in special situations.

Transpedicular Approach

The transpedicular approach may be used for thoracic disc removal and vertebral body biopsy.⁵⁴ It may also be performed in the cervicothoracic junction. The prone position is used with the transpedicular approach.

A midline vertical incision is performed (see Fig. 169-24A). The paraspinous muscles and the soft tissues are retracted to one side. The facet joint and the pedicle are removed by using a high-speed bur. The dorsal aspect of the vertebral body adjacent to the portion of the vertebral body near the rostral intervertebral disc space may be reached through the pedicle.

The exposure provided by the transpedicular approach, however, is limited. It allows only partial tumor or disc removal.

Costotransversectomy

This approach allows exposure of dorsal and dorsolateral structures, without violating the pleural cavity. It is different from the lateral extracavitary approach, because it involves a midline exposure and a plane of dissection that is medial to the erector spinae muscles. It was first described for drainage of tuberculous abscesses.⁵⁵

The patient is placed in the prone position and a midline vertical incision is made (see Fig. 169-24A). A modified T-shaped incision has also been described⁵⁶ (Fig. 169-24E). After standard bilateral subperiosteal dissection, a plane of dissection on the ipsilateral side is extended to the tips of the transverse processes and proximal ribs. The 3- to 4-cm medial aspect of one or two ribs is then cut, disarticulated from its costotransverse and costovertebral articulations, and resected.

To find the ipsilateral pedicle, the neurovascular bundle is identified under the rib bed and followed proximally to the neural foramen. After the transverse process and the pedicle have been removed, the lateral aspect of the thecal sac is visualized. Self-retaining retractors are used.

There is a controversy over the necessity of performing a rhizotomy of the associated nerve root during the procedure. Since the patients whose nerve roots were preserved can show late neuropathic pain, routine transection of the associated nerve root proximal to the ganglion may be desirable.³

Lateral Extracavitary Approach

The lateral extracavitary approach is a modification of costotransversectomy. It was introduced and popularized by Larson et al.⁵⁷ and then adopted by other surgeons.^47,58,59 The prone position is used frequently, although a three-quarter prone position has also been described (Fig. 169-25).⁵⁸ Several variations of a parasagittal incision are described (see Fig. 169-24).²³ Larson et al.⁵⁷ use a midline hockey-stick incision. This approach provides simultaneous access to both the dorsal and ventral aspects of the spine. Dorsal instrumentation may be placed via the same incision that is used for decompression.

FIGURE 169-25 The three-quarter prone position used for lateral extracavitary approach.

Dissection is carried to the lateral border of the paraspinous muscles. The paraspinous muscles are mobilized in a lateral-to-medial direction. They may also be transected in a transverse fashion as was originally described by Capener.⁶⁰ The lateral exposure reaches 8 to 10 cm lateral to the midline. The remaining portion of the operation is similar to the costotransversectomy. It differs from the costotransversectomy, however, because an approximately 15% to 30% ventral angle of exposure is gained by the lateral extracavitary approach (Fig. 169-26).

FIGURE 169-26 Alternative approaches to thoracic and lumbar spine: dorsal laminectomy (A), transpedicular approach (B), costotransversectomy (C), lateral extracavitary approach (D), and ventral intracavitary approach (E).

The disadvantages of transpedicular, costotransversectomy, and lateral extracavitary approaches are that they cannot be used for directly ventrally located lesions. Removing the facet joint and pedicle may destabilize the spine.

Dorsal En Bloc Total Spondylectomy

En bloc total spondylectomy may be performed by bisecting the affected vertebrae through the pedicles and removing the vertebra en bloc.²⁷ This method was first introduced by Tomita et al.^61,62 and then used in other centers.^63,64 There are two variations described in the following paragraphs.²⁷

Single Dorsal Approach: For Lesions from T1 to L2

Tomita et al.^27,61,62 proposed the removal of the dorsal component and lateral components of the spine en bloc by pediculotomy using a fine threadwire saw. If the unilateral pedicle is affected by the tumor, osteotomy may be performed through a neighboring healthy lamina. The involved nerve root occasionally had to be ligated and cut. If the affected pedicle or vertebral body markedly compressed the nerve root, the more severely affected side is sacrificed. Sacrificing both nerve roots in less important areas such as the thoracic spine is possible. After the dorsal bony column has been removed, the epidural venous bleeding is controlled (Fig. 169-27).

FIGURE 169-27 Dorsal en bloc total spondylectomy with single dorsal approach is suitable for lesions from T1 to L2. First, bilateral pediculotomy with the aid of a thin Gigli saw and resection of laminar arch is accomplished. After resection of the related nerve roots and dissection of ventral vascular structures, the vertebral body is removed by cutting through disc spaces.

(Redrawn from Tomita K, Kawahara N, Baba H et al: Total en bloc spondylectomy for solitary spinal metastases. Int Orthop 18:291–298, 1994.)

After resection of the neural arch, a Gigli saw is inserted to cut the upper and lower levels of the vertebral body or disc into two retractors protecting the ventral venous structure and two retractors protecting the spinal dura mater. During the operation, the spinal column is stabilized by connecting the unilateral rod to pedicle screws. Then the affected vertebra is removed dorsolaterally.

This operation is completed by using a long-segment dorsal instrumentation and placing a ventral vertebral body prosthesis (i.e., methylmethacrylate, bioactive ceramic, mesh cages, titanium mesh cylinder). Strut and cancellous bone grafts from the resected ribs or fibula are placed around the prosthesis and rods.

Transpleural Thoracotomy

When a ventrolateral exposure of the spine is required for pathologic processes located rostral to the T12 vertebral body, a transthoracic approach is often appropriate.^23,36,65 It is most useful for the midthoracic segments between T3 and T11.

The main advantage of a thoracotomy is direct access to ventral pathology, multilevel exposure, and ease of ventral instrumentation. The disadvantages of this approach include violation of the thoracic cavity, the need for a tube thoracotomy, and a relatively weak instrumentation construct (short-segment fixation).

The patient is placed in the lateral decubitus position. Usually, the right lateral decubitus position is used. Most surgeons prefer a left-sided approach because it is easier to mobilize the aorta than the vena cava. To open the intercostal and intervertebral spaces on the operative side, a slight break in the table or cushions placed under the contralateral thorax is necessary. The lower arm should be protected by axillary rolls. The upper arm can rest on an arm table or over the cushions. The upper leg is flexed, and the lower leg is extended.

A curved incision is fashioned around the medial aspect of the scapula for a thoracotomy in the upper thoracic spine (T2-5) vertebral lesions (Fig. 169-28). For lesions between T5 and T10, a curvilinear incision is made along the designated rib, extending from the costochondral articulation ventrally to the lateral aspect of the paraspinous muscles dorsally (see Fig. 169-23A).

FIGURE 169-28 Skin incision for ventrolateral exposure of the upper thoracic spine. The right-side-up position and a curved incision around the scapula finishing at the C7 spinous process are used.

The optimal rib to be resected in the thoracic spine is the rib that is located at the level of the surgical pathology in the midaxillary line. Muscle and periosteum may be divided with monopolar cautery. The rib is then dissected subperiosteally with a small periosteal dissector. Resection of the rib is not essential. The pleura is then opened in the bed of the rib. After retraction of the lung, the spine is visualized. Segmental vessels in the desired area are ligated and divided. The periosteum on the ventrolateral spine is incised and retracted.

After the lung is collapsed, a self-retaining thoracotomy retractor is used. A malleable retractor with a reversed curve is placed on the ventral aspect of the vertebral body.⁶⁶

Extrapleural Thoracotomy

An extrapleural thoracotomy approach provides a shorter route to the ventral thoracic spine. Its major advantage is avoidance of pleural cavity violation.⁶⁷ Postoperative morbidity, particularly pain and pulmonary complications, are thus reduced.

The patient is placed in the lateral decubitus position. As with a transpleural thoracotomy, a curved incision is fashioned around the medial aspect of the scapula.

Intercostal muscles are detached subperiosteally over an 8- to 10-cm rib segment.⁶⁷ Then, in the resected rib segment, the endothoracic fascia is incised in line with the rib bed. The parietal pleura is widely dissected from the undersurface of the endothoracic fascia with blunt dissectors. After adequate dissection and freeing the parietal pleura over the vertebral body is ensured, a self-retaining crank-type retractor facilitates the exposure.

Retropleural approaches are recommended to avoid direct lung trauma and to minimize the need for a tube thoracostomy. In the midthoracic spine, only limited lesions such as thoracic disc herniations may be approached via a retropleural thoracotomy. It is easier to perform an extrapleural operation at the thoracolumbar junction. The 11th or 12th rib extrapleural-retroperitoneal approach is a prototype for this.⁶⁸ The extrapleural space can be expanded to T10-L2. Some authors have advised resectimg the 12th rib to facilitate exposure.⁶⁷

Transdiaphragmatic Approach

To approach the T11 or T12 vertebrae, either a supradiaphragmatic or infradiaphragmatic exposure may be possible. However, it is usually necessary to section the diaphragm to reach the L1 vertebral body.

The diaphragm is a key structure that should be taken into consideration for approaches to the thoracolumbar spine. Its limbs have attachments to the L1 transverse process and vertebral body. It extends laterally over the quadratus lumborum muscle to the tip of the 12th rib. Because its innervation from the phrenic nerve begins centrally, a peripheral incision is preferred. If a transdiaphragmatic approach to reach the ventral thoracolumbar junction is mandatory, the pleural and retroperitoneal cavities are violated. Because the morbidity of such an approach is higher than that of a retroperitoneal approach, which violates only one body cavity, it should be used only if absolutely necessary.

The patient is placed in the lateral decubitus position. For the thoracolumbar junction, the classical operation is the 9th or 10th rib transpleural-retroperitoneal thoracoabdominal approach. Most commonly, a T10 rib incision is made. The 10th rib may then be resected (Fig. 169-29). A self-retaining thoracotomy retractor is used as for thoracotomy. Care must be taken not to injure the spleen on the left side or the liver on the right side. The major disadvantage of this method is the division of the diaphragm and entering into two body cavities.

FIGURE 169-29 The incision lines for thoracotomy and lumbar ventrolateral retroperitoneal approaches: a, lower thoracotomy; b, T12-L1; c, L1-2; d, L2-3; e, L3-5; f, L5-S1 retroperitoneal approaches; and g, transperitoneal approach.

Kim et al.⁶⁸ have recommended using an 11th rib extrapleural-retroperitoneal approach (Fig. 169-30). Since it prevents entering the pleural cavity, thoracic complications should be minimal. However, it is technically demanding, it prolongs the operative time, and the operative exposure is limited.

FIGURE 169-30 Eleventh rib extrapleural-retroperitoneal approach for lesions in the thoracolumbar spine. A left-sided approach is mostly preferred (A). After removing the 11th rib (B), a self-retaining retractor is placed, and with blunt dissection, ventral vertebral structures are shown (C).

(Redrawn from Kim M, Nolan P, Finkelstein JA: Evaluation of 11th rib extrapleural-retroperitoneal approach to the thoracolumbar junction: technical note. J Neurosurg 93[1S]:168–174, 2000.)

Ventrolateral Retroperitoneal Approach

It is possible to reach the lumbar vertebrae from L1 to L5 with an extraperitoneal approach. Ventral instrumentation, however, is difficult below L4 because of the constraints of the iliac vessels and overlying iliac crest.

A supine position is appropriate for low ventrolateral lumbar exposure, using a log roll to elevate the operative side. For thoracolumbar approaches, however, a right lateral decubitus position on an ordinary operating table is preferred. Table-mounted retractor systems may help to maintain this position during the operation.

The left-side-up position is preferred because it is easier to dissect, mobilize, or repair the aorta or iliac artery compared with the vena cava or iliac vein. The liver, because of its mass and location, is more difficult to retract and mobilize than the spleen is. Excessive splenic retraction may result in injury. An adjustable pad is placed at the level of the vertebra of interest.

The skin incision is run obliquely, caudally, and ventrally. This so-called flank incision can be made between the tip of the 12th rib and the anterior superior iliac spine. It begins dorsally at the edge of the paravertebral muscle and terminates at the lateral margin of the rectus abdominis muscle. However, the incision may vary on the basis of the spinal level and the surgical indication (see Fig. 169-29).²³

For an infradiaphragmatic retroperitoneal exposure, subperiosteal dissection of the crus of the diaphragm from its vertebral attachments aids in the visualization of the higher lumbar and lower thoracic vertebral bodies. Resection of the 11th or 12th rib may be used to gain access to the thoracolumbar and upper lumbar spine via this approach.^69–71

The exposure to the midlumbar spine is the same approach that is used for the lumbar sympathectomy. This exposure allows access to the ventrolateral spinal canal from L2 to below the pelvic brim. The advantages of this approach are its familiarity to all spine and vascular surgeons and its direct exposure of the midlumbar vertebral bodies. However, it provides a narrow longitudinal exposure that is limited rostrally by the crus of the diaphragm and caudally by the pelvic brim. The psoas muscle also limits the opening of neuroforamina.

It is very important to clearly conceptualize the pathologic levels. For example, if only the L1-2 disc space is to be surgically approached, a subcostal extrapleural, T12 rib resection approach without diaphragm incision should be considered. Excessive left-sided retraction may result in splenic injury. If an L1 corpectomy is needed, a transdiaphragmatic approach may be preferred, depending on the patient’s anatomy.

The external oblique, internal oblique, and transversus abdominis muscles are split with cutting diathermy. Retraction of the peritoneal sac ventrally and medially away from the psoas muscle exposes the vessels located ventral to the spine. The attachments of the psoas muscle are dissected laterally and dorsally.

Ligature of the segmental lumbar vessels is necessary. After this ligation, the aorta and the inferior vena cava may be retracted ventrally and medially. Then a malleable retractor may be used to retract the peritoneal sac and the great vessels.

The vascular supply of the spinal cord is worthy of consideration. The most common location of the entrance of the radiculomedullary artery of Adamkiewicz into the spinal canal is on the left, in the midthoracic to lower thoracic region. Generally, the ventrolateral approach is not affected by the location of radiculomedullary arteries, because the angle of the approach does not violate terminal-end arteries. If the surgeon intends to disrupt the soft tissues at the level of the neuroforamina, terminal spinal cord blood flow may be endangered. In this circumstance, an alternative approach should be considered.

Lumbar Laminectomy and Laminotomy

Because opening of the interlaminar space is important, the patient should not be in extreme lordosis. A standard dorsal midline incision is performed. If a single-level microdiscectomy is planned, the length of the incision may be as short as 2.5 cm. An intraoperative radiograph is necessary to confirm the correct level.

Hemilaminectomy retractors are used for two or more level single-sided discectomies. For microdiscectomy, specially designed retractors such as Caspar retractors may be used.

Paraspinal Approach

The paraspinal approach is used for far-lateral disc herniation⁷² or for dorsolateral fusion of the transverse processes.⁷³ Its main advantage is the decrease in paraspinous muscle retraction.

The patient is placed in the prone position. Wiltse et al.⁷³ have described bilateral paramedian incisions and a muscle-splitting dissection between the erector spinae and multifidus muscles. If the operation is performed for an extraforaminal disc protrusion, a unilateral small incision is usually sufficient.

The paraspinal approach provides a direct exposure of the intertransverse region and the facet joint. A self-retaining retractor may be used between the muscles.

Jane et al.⁷² have described a modification of this approach that makes it possible to expose the root both from medial and lateral to the facet joint. With this approach, the incision is extended from the midline, but the muscle fascia is incised as an arc, and the spaces first medial to the paraspinous muscles and then lateral to these are exposed.⁷²

Lateral Extracavitary Approach

The lateral extracavitary approach in the lumbar spine is similar to the lateral extracavitary approach in the thoracic spine. However, it is more important to preserve the lumbar nerve roots. Because there is no rib in the lumbar region and because the nerve roots pass through the bulky iliopsoas muscle, the lateral extracavitary approach is technically demanding in the lumbosacral region. The obstacle of the iliac crest is another limitation of this approach.^5,49,50,57

Ventrolateral Transpsoatic Approach

Although this technique was used to implant prosthetic disc nucleus devices in patients with symptomatic degenerative disc disease,⁷⁴ it was then called an extreme lateral interbody fusion, and for the risks of iatrogenic injury to the lumbosacral plexus, electrophysiologic monitoring of the retracted roots inside the psoas muscle is recommended.⁷⁵

Pelvic Brim Extraperitoneal Approach

The pelvic brim extraperitoneal approach provides a limited exposure of the L5 and S1 levels, because of the obstructing iliac vessels and the iliac crest. For this reason, only limited procedures, such as biopsy and simple resections, can be performed.

Usually, the supine position will suffice with slight elevation on the side of surgery with a log roll. An incision beginning lateral to, and slightly above, the anterior superior iliac spine can be carried medially and caudally. It must be parallel and rostral to the iliac crest and inguinal ligament.

The peritoneum and renal fascia are retracted medially, with great care taken not to injure the retroperitoneal nerves and ureters. This exposure provides a limited view of the vertebrae under the aorta and iliac arteries.

For a minimally invasive exposure of the L4-5 level, a 5- to 8-cm horizontal incision through the anterior rectus sheath has been described. The rectus abdominis muscle is then retracted medially. After incision of the posterior rectus sheath, the retroperitoneum is exposed.^23,58,70

Transperitoneal Approach

It is possible to reach all the midlumbar and lower lumbar segments and the sacrum via the transperitoneal approach.^66,76,77 The transperitoneal approach provides a direct ventral exposure of the lumbar and sacral spine. It is most useful for L5-S1 pathology, when a wide exposure of this region is required.⁷⁸ The requirement of a laparotomy and the potential for neural and vascular injury are its disadvantages.

The patient is placed in the supine position. A midline or horizontal subumbilical laparotomy incision is made.

After entry into the peritoneal cavity, the small intestines are packed in the upper abdomen and retracted to the right. A break in the operating table to increase the lumbar lordosis is useful. Care is taken to avoid injury to the bladder. The sigmoid colon is retracted laterally, and a longitudinal incision is made in the dorsal peritoneum in the midline. The sacral promontory is an important landmark. The sigmoid colon limits the exposure on the left side, but caudal retroperitoneal structures on the right side are easily identified.

The bifurcation of the iliac arteries and veins does not allow exposure above the L5 vertebral body through the bifurcation. Instead, the approach is to the left of the vessels. Liberal use of epinephrine injection and, in males only, use of bipolar electrocautery decreases the risk of presacral plexus injury.

Retroperitoneal Approach

The retroperitoneal approach is restricted to the sacral pathologies without rectal invasion. Depending on the extent of the pathology, a unilateral or bilateral retroperitoneal dissection may be used.

A supine position with the legs elevated and partly separated (lithotomy position) is advised.⁸⁰ If a unilateral dissection is planned, one side of the pelvis may be elevated.

For bilateral retroperitoneal exposure, a large semicircular incision is performed through the skin on the lower abdomen (Fig. 169-33A). The rectus abdominis tendon is severed bilaterally just above the pubic bone. For unilateral exposure, a flank incision without violating the rectus abdominis muscle is satisfactory (Fig. 169-33B).

FIGURE 169-33 Different incisions used for ventral sacral operations: A, bilateral U-shaped retroperitoneal incision; B, unilateral flank retroperitoneal incision; C,ventral medial transperitoneal incision.

After dissection and medial retraction of the peritoneum, common iliac arteries and veins with external and internal branches are exposed. Then the dorsal parietal peritoneum is dissected medially together with the ureter and the superior hypogastric nerve plexus. The right and left dissections meet in the midline. Deep handheld abdominal retractors are used for retraction of the deep abdominal structures.

Transperitoneal Approach

The transperitoneal approach is primarily used for L5-S1 ventral fusion operations. It may also be used for the resection of sacral tumors, if the rectum has to be included in the specimen.

The patient is placed in the supine position, and an inferior midline abdominal incision is made (Fig. 169-33C). The median raphe of the rectus abdominis muscle is divided. A suprapubic transverse incision is not recommended, for it requires a rectus abdominis muscle section.

The peritoneum is cut in the midline, and after packing the bowel and small intestines rostrally and laterally, the rectum is released ventrally as far distally as possible.

Combined Abdominosacral Approach

Total resection of the major primary sacral tumors (i.e., chordoma, chondrosarcoma, giant cell tumor) requires a combined approach, both ventral and dorsal.^39,81 If the rectum can be preserved, the operation is begun ventrally and finished dorsally. If not, a ventral, dorsal, and ventral approach sequence is advocated.⁸⁰

Some surgeons prefer a dorsal exposure in the prone position. The patient is then placed in the lateral decubitus position so that a separation of tissue planes from both sides is possible.^43,82 In this case, two surgeons, one from the dorsal and the other from the ventral side, may operate simultaneously.