Summary of Key Points
Surgical positions, incisions, and retractors are reviewed for cervical, thoracic, lumbar, and sacral locations.
Technical details of various surgical approaches are outlined.
Anatomy of ventral, dorsal, and combined approaches and how to avoid complications are discussed. Minimally invasive techniques are also outlined.
Ventral approaches to craniocervical junction include the transoral approach, the endoscopic transnasal approach, median labiomandibular glossotomy, the transmandibular and transthyroid approach, the ventrolateral retropharyngeal approach, and the lateral cervical approach.
Ventral approaches to subaxial cervical spine include the ventromedial and ventrolateral approaches.
Ventral approaches to the cervicothoracic junction include the transsternal, transmanubrial, transverse supraclavicular, transclavicular, transaxillary extrapleural, lateral parascapular extrapleural, transpleural transthoracic, and trapdoor approaches.
Dorsal approaches to thoracic spine are reviewed, including thoracic laminectomy, the transpedicular approach, costotransversectomy, the lateral extracavitary approach, and dorsal en bloc total spondylectomy.
Ventral approaches to the thoracic and thoracolumbar junction include transpleural thoracotomy, extrapleural thoracotomy, the transdiaphragmatic approach, and the ventrolateral retroperitoneal approach.
Ventral approaches to the lumbar and lumbosacral spine include the lateral transpsoas, pelvic brim extraperitoneal, and transperitoneal approaches.
Ventral approaches to sacrum include the retroperitoneal, transperitoneal, and combined abdominosacral approaches.
A variety of ventral and dorsal incisions are used to gain access from the upper cervical to the lower sacral spine. Appropriate positioning plays an important role in minimizing blood loss and providing adequate exposure of the spine. Tissue retraction plays an equally important role. Table 197-1 presents an overview of approaches and corresponding incisions. This chapter focuses on surgical decisions, patient positioning, and retraction techniques to avoid complications during surgery.
|H igh C ervical S pine|
|Dorsal approaches||Suboccipital craniectomy C1–2 laminectomy||Dorsal midline|
|Lateral transcondylar approach||Hockey-stick, retromastoid|
|Ventral approaches||Transoral approach||Midline pharynx|
|Median labiomandibular glossotomy||Median lower lip, mandible, tongue|
|Transthyroidal approach||Transverse below hyoid bone|
|Ventrolateral retropharyngeal approach||T-shaped submandibular or hockey-stick|
|Lateral approaches||SCM may be cut||L-shaped incision below mastoid process|
|S ubaxial C ervical S pine (C3-T1)|
|Dorsal approaches||Laminoforaminotomy for cervical disc disease||Dorsal paramedian|
|Ventral approaches||Ventromedial approach||Parallel to skin crests or SCM|
|Ventrolateral approach–medial to the carotid artery||Parallel to SCM|
|Ventrolateral approach–lateral to the carotid artery||Parallel to SCM|
|C ervicothoracic J unction (C7-T3)|
|Dorsal approaches||Laminectomy||Dorsal midline|
|Ventral approaches||Lower ventral-medial cervical approach||Parallel to SCM|
|Transsternal approach||T-shaped; extending midsternum|
|Transmanubrial approach||T-shaped; or parallel to SCM extending midsternum|
|Transverse supraclavicular approach||Parallel to clavicle|
|Transaxillary extrapleural approach||Subaxillary, parallel to T3 rib|
|Transpleural-transthoracic approach||Parallel to T3 rib|
|T horacic and T horacolumbar S pine|
|Dorsal approaches||Thoracic laminectomy||Dorsal midline|
|Transpedicular approach||Dorsal midline|
|Costotransversectomy||Curved to one side paramedian|
|Lateral extracavitary approach||Curved to one side paramedian or hockey-stick|
|Dorsal en bloc total spondylectomy||Dorsal midline|
|Ventral approaches||Transpleural thoracotomy||Parallel to rib|
|Transdiaphragmatic approach||Flank incision|
|Ventrolateral retroperitoneal approach||Flank incision|
|L umbar and L umbosacral S pine|
|Dorsal approaches||Lumbar laminectomy||Dorsal midline|
|Lateral extracavitary approach||Paramedian|
|Ventral approaches||Extreme lateral interbody fusion approach (XLIF) or ventrolateral transpsoas approach||Lateral lumbar|
|Pelvic brim extraperitoneal approach||Lower flank incision|
|Transperitoneal approach||Midline/horizontal subumbilical laparotomy incision|
|Dorsal approaches||Dorsal approach||Dorsal midline|
|Ventral approaches||Retroperitoneal approach||U-shaped suprapubic incision|
|Transperitoneal approach||Midline subumbilical laparotomy incision|
Appropriate patient positioning in the operating room is optimally determined by the combined efforts of the surgeon and the neuroanesthetist.
An advantage of the sitting position is that it directs blood away from the surgical site ( Fig. 197-1 ). The risk of air embolism, however, is a major disadvantage. Furthermore, if the patient is quadriplegic (with a decrease in sympathetic tone), the resulting hemodynamic changes and hypoperfusion associated with the sitting position may compromise the perfusion of the spinal cord. Therefore, the sitting position requires a competent anesthetist as well as right atrial and pulmonary artery catheterization, Doppler ultrasound heart monitoring, and end-tidal CO 2 monitoring.
Ventral Cervical Operations
A bolster beneath the neck and the interscapular region enhances cervical extension. Cervical distraction may be achieved by cervical traction or interbody distraction techniques.
In the lateral decubitus position, the table may either be neutral or slightly extended to extend the rib cage. In this position, care should be taken to avoid compression of the brachial plexus; therefore, a roll should be placed under the axilla. The upper arm should be abducted no more than 90 degrees. The elbow must be properly padded ( Fig. 197-2 ).
Three major types of retractors are used in spine surgery: handheld retractors, patient-mounted self-retaining retractors, and table-mounted self-retaining retractors. Because intraoperative radiographs are commonly used in spine surgery, radiolucent retractors may be very helpful.
Self-retaining retractors are usually necessary to maintain an open mouth and to depress the tongue. Self-retaining retractor rings are fixed on the upper and lower teeth ( Fig. 197-3 ). Table-mounted retractors are attached to the operating table to retract both the palate and the tongue. These retractors may also hold the neck in a fixed position; thus, they may eliminate the need for additional skeletal traction.
Ventral Cervical Retractors
Handheld retractors with blunt tips are useful for the dissection phase of the operation. For subsequent phases of ventral cervical operations, the most commonly used self-retaining retractors are the Caspar (Aesculap, Tuftlingen, Germany; Fig. 197-4 ), Apfelbaum (Aesculap; Fig. 197-5 ), Cloward (Codman, Raynham, MA), and Farley-Thompson retractors (Thompson Surgical Instruments, Traverse City, MI; Fig. 197-6 ).
The transverse blades of self-retaining retractor systems often have teeth that should be placed under the longus colli muscles to avoid damage to the esophagus and carotid artery. The longitudinal blades are smooth.
A modified Caspar retractor has been recommended for ventrolateral foraminotomy; it enables retraction of the longus colli muscle laterally and facilitates vertebral artery retraction. Table-mounted retractors have also been used in some anterior cervical surgeries especially during anterior odontoid screw fixation.
Ventral Thoracic and Lumbar Retractors
A crank-type retractor is useful to distract the ribs. The lungs as well as the diaphragm or retroperitoneal organs are retracted with lung and abdominal handheld retractors. Although they may narrow the operating space, the placement of laparotomy sponges under retractor blades helps to prevent damage to the viscera. The disadvantages of handheld retractors include the risk of visceral organ damage and the difficulty of manually maintaining sufficient retraction force. Table-mounted systems retract both the rib cage and the lungs.
Dorsolateral Thoracic and Lumbar Retractors
The lateral extracavitary approach to the thoracic and lumbar spine requires significant retraction. A rostral and caudal self-retaining tissue-mounted retractor may be used to medially retract the paraspinous muscles. A wide-diameter, malleable retractor can be used to laterally retract the muscles of the chest wall or the lumbodorsal muscles. Either handheld or table-mounted retractors may be used.
Dorsal Approaches to the Upper Cervical Spine
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. 197-7 and 197-8 ).
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 has recommended using two retractors placed at 90 degrees to each other to prevent motion of the occipitocervical and atlantoaxial joints.
Lateral Transcondylar Approach
The lateral transcondylar approach is also termed the extreme lateral trans-condylar 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 brain stem, 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. 197-9 ). 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.
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 brain stem should not be retracted. Some surgeons find that removing the occipital condyle is not necessary and use the term posterolateral suboccipital retrocondylar approach .
Salas and colleagues 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.
Ventral Approaches to the Upper Cervical Spine
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. 197-3 ).
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. 197-1 ).
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. The primary difficulty with this approach related to working with long instruments in a deep opening. Assistance of an endoscope may be quite useful which can decrease the need for extensive soft palate splitting, hard palate resection, or extended maxillotomy.
Endoscopic transnasal odontoidectomies may be performed. The main advantage of a transnasal approach is to avoid transection of the palate, which would have required during a transoral operation.
Median Labiomandibular Glossotomy
Median labiomandibular glossotomy provides a wide ventral exposure from the clivus to the lower cervical spine. A midline vertical incision starts from the lower lip, extends caudally, turns around the chin prominence, and again passes medially in the neck ( Fig. 197-10 ). 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.
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.
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. 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.
The transthyroid approach may provide access to the first four cervical vertebrae. A transverse incision is carried along the upper neck crease, between the hyoid bone and the thyroid cartilage, and is extended laterally ( Fig. 197-11 ). The platysma and sternohyoid muscles are divided, and the thyrohyoid membrane is detached from the hyoid bone while the epiglottis is protected.
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.
Ventrolateral Retropharyngeal Approach
The ventral retropharyngeal approach provides access to structures from the clivus to the third cervical vertebrae without entering the oral cavity. 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. 197-12A ). Another option is a V-shaped incision ( Fig. 197-12B ).
This ventral retropharyngeal approach may be called retrovascular or prevascular surgery ( Fig. 197-13 ). Prevascular surgery involves an access medial to the carotid sheath and traverses the same fascial planes as in the ventrolateral lower cervical spine surgery (see Fig. 197-13B ). 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.
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. It may be difficult to place a self-retaining retractor in this opening. A table-mounted system may be useful in this region.
This approach may also be performed in a minimally invasive fashion with a tubular retractor placed through a window between the hypoglossal nerve and the superior laryngeal nerve
Lateral Cervical Approach
Some authors refer to the lateral cervical approach as a retrovascular variant of the ventral retropharyngeal approach. 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, VII ( Fig. 197-14 ). Although it provides 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. The major difference between a ventrolateral retropharyngeal approach and a straight ventral retropharyngeal approach is that the exposure is lateral to the carotid sheath.
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. 197-12C ).
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.
This approach may be fashioned for primary tumors of the upper cervical spine ( Fig. 197-15 ) especially for laterally situated C1 tumors. If necessary, an occipitocervical fusion may be performed at the same session.
Dorsal Approaches to the Subaxial Cervical Spine
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. Injury to supraspinous ligaments should be avoided. 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 positions may be used: the prone position, the sitting position, and the lateral or park-bench position. 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.
A midline dorsal or paramedian dorsal incision may be used. The dorsal paramedian incision is used only for single-level laminoforaminotomy. 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.
The classical midline dorsal approach requires the resection of the muscle attachments from the spinous processes to expose the facets and laminae. Only strong lateral retraction is needed to retract the muscles.
Ventral Approaches to the Subaxial Cervical Spine
Exposure of the disc space and vertebral body is usually accomplished by a ventromedial approach. 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. 197-14 ). Rengachary has suggested 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. 197-14 ).
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. 197-16A ). 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.