Anterior Transcervical Approach to the Cervical Spine




Introduction


The otolaryngologist is often involved in surgery to provide access to the cervical spine. This is usually for the treatment of cervical spondylosis by the orthopedic or neurologic surgeon. Rarely the head and neck surgeon will be involved in the treatment of pathology involving the spine, such as infection or primary and metastatic neoplasms. Potential benefits for the primary surgeon of the participation of the otolaryngologist include increased efficiency, decreased risk of injury to the vagus nerve or esophagus, decreased medicolegal risk, and follow-up care of voice and swallowing problems.


Familiarity with these approaches is also important for the treatment of conditions that do not involve the spine, such as deep neck infections, retropharyngeal lymph node metastases, and cricopharyngeal achalasia with Zenker’s diverticulum. Surgical approaches to the cervical spine can be categorized as anterior cervical, lateral cervical, transoral, and transnasal approaches. This chapter will focus on anterior transcervical approaches to the cervical spine. Transoral and transnasal approaches to the upper cervical spine are included in Chapter 123 .




Key Operative Learning Points





  • C1 and C2 are at or above the level of the body of the mandible. C3 and C4 are at the level of the hyoid bone and the superior aspect of the thyroid cartilage. C5 and C6 are at the level of the posterior cricoid cartilage. C7 is at the lower limit of the neck and may be below the level of the clavicle in some patients.



  • The anterior cervical spine is approached medial to the carotid sheath and lateral to the strap muscles.



  • The superior laryngeal nerve courses across the neck deep to the carotid artery at the level of the thyrohyoid membrane and is in close association with the superior thyroid artery.



  • The recurrent laryngeal nerve is situated in the tracheoesophageal groove superficial to the plane of the prevertebral fascia and enters the larynx at the cricothyroid joint.



  • Injury to the recurrent laryngeal nerve can be avoided by maintaining a plane of dissection deep to the nerve.



  • In revision surgeries, the carotid artery is medially displaced due to scar contracture and at greater risk of injury.



  • Lateral to the vertebral bodies, the vertebral artery courses within the vertebral canal of the lateral processes.



  • The lateral retropharyngeal lymph nodes (nodes of Rouviere) are situated just medial to the internal carotid artery at the level of the transverse process of the first cervical vertebra (atlas).





Preoperative Period


History




  • 1.

    History of present illness




    • Pain


      Patients may have pain in the neck or shoulders from nerve root compression from cervical spondylosis; it may radiate to the upper extremities. Pain may also be exacerbated by movement of the neck.



    • Neurologic dysfunction


      Patients may have sensory and motor loss from spinal cord compression. Patients should be questioned about sensory loss or weakness of the extremities (decreased grip strength, difficulty ambulating).



    • Hoarseness


      Patients who have had prior cervical surgery should be questioned about hoarseness following prior surgery. Hoarseness may signal vocal cord paresis from injury to the recurrent laryngeal nerve. Decreased vocal range with coughing due to aspiration may be associated with injury to the superior laryngeal nerve.



    • Dysphagia


      Dysphagia is often multifactorial. Large osteophytes can cause compression of the esophagus with dysphagia for solids. Dysphagia with regurgitation of undigested food is suggestive of a Zenker’s diverticulum.



  • 2.

    Past medical history




    • Prior cervical spine surgery


      In patients with a prior history of cervical spine surgery, it is important to inquire about the indications for the previous surgery, the operated spine levels, postoperative complications, and the duration of postoperative symptoms. Prolonged hoarseness after surgery may indicate injury to the recurrent laryngeal nerve.



    • Other neck surgery or trauma to the cervical spine


      Other operations in the cervical region such as thyroidectomy should be noted.




Physical Examination





  • Inflammation


    Inflammatory conditions such as osteomyelitis or retropharyngeal abscess can result in erythema and edema of the soft tissues. Rarely, crepitus from subcutaneous air is palpable if there is communication with the pharynx or esophagus.



  • Range of motion


    Cervical osteophytes may limit the range of motion of the neck (flexion, extension, rotation). Patients with Forestier’s disease or diffuse idiopathic skeletal hyperostosis (DISH) often have limited flexion/extension due to extensive calcification of the anterior longitudinal ligaments.



  • Mass in the neck


    A mass in the neck may be inflammatory or neoplastic. A large Zenker’s diverticulum is rarely palpable. A large thyroid goiter may interfere with a low cervical approach.



  • Evidence of prior surgery


    The side and level of prior surgical approaches to the cervical spine should be noted, since this may have an impact on the surgical approach. If a new level is targeted, it may not be possible to use the same incision.



  • Upper airway


    The upper airway should be examined by endoscopy to assess the safety of the airway for intubation. Large osteophytes posterior to the pharyngeal mucosa may limit access to the airway.



  • Neurologic function


    The function of the larynx should be assessed by laryngoscopy. If there is paresis of a vocal cord, this should be clearly documented.



Imaging





  • Lateral plane radiograph


    Anterior-posterior and lateral spine radiographs provide basic details of bone anatomy and are good for visualization of spinal hardware. The optimal placement of the skin incision can be determined based on the relationship of the cervical spine level to the bony/cartilaginous landmarks of the hyoid bone and thyroid cartilage.



  • Esophagram


    If there is suspected perforation of the esophagus, an esophagram is obtained using a water-soluble contrast agent. An esophagram or modified barium swallow is also helpful in assessing the severity and contribution of osteophytes to dysphagia.



  • Computed tomography (CT)


    A CT scan with contrast should be considered in patients with associated symptoms or physical findings suggestive of a neoplasm or osteomyelitis. A sagittal view provides optimal viewing of cervical hardware: cervical spine levels, displaced hardware, compression of esophagus ( Fig. 77.1 ).




    Fig. 77.1


    Sagittal plane computed tomography scan demonstrates position of cervical hardware as well as relationships of laryngeal landmarks to cervical spine levels. In this patient, there is compression of the esophagus by the hardware.



  • Magnetic resonance imaging (MRI)


    MRI is superior for delineating the level of cord compression from a herniated disc ( Fig. 77.2 ).




    Fig. 77.2


    Preoperative magnetic resonance image (sagittal plane) demonstrating the relationships of the cervical vertebrae to palpable laryngeal landmarks, as well as significant spinal cord compression at the C5-C6 and C6-C7 levels due to cervical spondylosis (arrows) (A = anterior).



Indications




  • 1.

    Cervical spondylosis


    The most common indication for an anterior approach to the cervical spine is cervical spondylosis ( Fig. 77.2 ). Revision surgery is sometimes necessary when there is infection or displacement of plating hardware. Bulky hardware may also contribute to postoperative dysphagia and may be removed electively to improve swallowing function. Large osteophytes occur most commonly at the C4-C6 levels in approximately 12% to 30% of the elderly and may be associated with symptomatic dysphagia and aspiration. It can be difficult to demonstrate that the patient’s symptoms are due to the osteophyte, however, since dysphagia is frequently multifactorial in these patients. Patients with Forestier’s disease or DISH can develop extensive calcification of the anterior longitudinal ligaments with resultant dysphagia ( Fig. 77.3 ). The calcifications usually span multiple levels.




    Fig. 77.3


    Forestier’s disease, or diffuse idiopathic skeletal hyperostosis, is characterized by extensive calcification of the anterior longitudinal ligaments (arrows).


  • 2.

    Cervical osteomyelitis


    Rarely infection of the vertebral bodies (osteomyelitis from adjacent infection or hematogenous seeding of the vertebral body; e.g., tuberculosis) may require surgery.


  • 3.

    Neoplastic involvement of cervical spine


    Malignancies metastatic to the vertebral bodies are usually treated with palliative radiation but may also require surgery for stabilization of the cervical spine.


  • 4.

    Retropharyngeal abscess


    Infection of deep neck spaces may result in a retropharyngeal abscess. This may result from a suppurative upper respiratory infection with involvement of the retropharyngeal lymph nodes, esophageal perforation, or a foreign body.


  • 5.

    Zenker’s diverticulum


    Although most cricopharyngeal myotomies for Zenker’s diverticulum are now performed endoscopically, an anterior cervical approach to the cervical spine provides the necessary exposure of the cricopharyngeus and inferior pharyngeal constrictor muscle for performance of a myotomy or excision of diverticulum with a myotomy, especially in patients who are not candidates for an endoscopic approach.


  • 6.

    Esophageal perforation


    An esophageal perforation may result from intraluminal trauma (e.g., passage of a tube or esophagoscope), erosion by spinal hardware, or iatrogenic injury from neck surgery. A transcervical approach provides drainage of air/fluid to prevent infection and allows primary surgical repair.


  • 7.

    Retropharyngeal lymphadenectomy


    Neoplasms of the soft palate, pharynx, thyroid, and skull base may metastasize to retropharyngeal lymph nodes. Although the survival is poor in patients with squamous cell carcinoma metastatic to the retropharyngeal lymph nodes, retropharyngeal lymphadenectomy may be beneficial in selected patients with other types of neoplasms (esthesioneuroblastoma, thyroid cancer).



Contraindications




  • 1.

    Active neck infection


    Untreated neck infection is a contraindication to cervical spine surgery with instrumentation, unless the patient requires surgical treatment of osteomyelitis. Staging of surgery may be necessary with surgical drainage of infection and medical therapy prior to spine surgery.


  • 2.

    Major medical comorbidities


    If a patient is not a candidate for general anesthesia, limited surgery for biopsy or drainage of an abscess can be performed with minimal sedation and local anesthesia.



Preoperative Preparation





  • Informed consent


    Informed consent includes a discussion of potential risks and expected sequelae of surgery. For anterior approaches, the greatest concern is postoperative hoarseness or aspiration due to injury to the superior or recurrent laryngeal nerves. Some degree of dysphagia is expected postoperatively and can persist for months in a minority of patients. The risk of infection or significant bleeding is negligible. Perforation of the esophagus or hypopharynx is a remote possibility, but the risk is increased when displaced hardware or a large osteophyte is being removed.



  • Neck incision


    The laterality of the incision is generally not important. Arguments can be made for either side, depending on the level of exposure, handedness of the surgeon, risk of retraction injury of the recurrent laryngeal nerve, deviation of the esophagus, and prior surgery. Most right-handed surgeons find a right-sided approach to be easier for instrumentation of upper cervical levels and a left-sided approach for instrumentation of lower cervical levels.


    Using the same side as a previous incision is preferred if the same cervical spine level is targeted, especially if spinal hardware needs to be removed. If there is paresis of a vocal cord or preoperative examination of the larynx was not performed, it is safer to operate on the same side to avoid possible paresis of the contralateral vocal cord.


    Assessment of the anatomic relationship of vertebral bodies to cartilaginous and bony landmarks is assessed with a lateral radiograph of the cervical spine or on CT or MRI (sagittal view; Figs. 77.1 and 77.2 ). The level of upper cervical vertebrae is judged based on their relationship to the hyoid bone. The level of midcervical vertebrae is best judged based on their relationship to the posterior cricoid cartilage and thyroid cartilage. Since cartilaginous landmarks are not well visualized on MRI, the epiglottis is a useful landmark. The anterior ring of the cricoid cartilage is a readily identifiable landmark for localizing the lower cervical vertebrae.



  • Neurophysiology


    Neurophysiologic monitoring of spinal cord function is performed intraoperatively when there is preoperative compression of the spinal cord or when surgery on the spinal cord is performed. If there is severe preoperative compression, a baseline study is performed after induction of anesthesia and prior to positioning. After positioning, the patient is reassessed to confirm that neurologic function has not worsened. Continuous monitoring is performed throughout surgery.



  • Navigation


    Intraoperative image guidance with a navigational system is helpful for pathology of the upper cervical spine and cranial base but is impractical for lower levels. When a navigational system is used, a CT angiogram will provide good visualization of bony anatomy, as well as the course of the vertebral artery.


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Apr 3, 2019 | Posted by in OTOLARYNGOLOGY | Comments Off on Anterior Transcervical Approach to the Cervical Spine

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