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Surgical Decision-Making for Cervical Spine Disease

Summary

Many factors contribute to the decision-making process regarding anterior versus posterior cervical spine surgery. Some of these include patient presentation, age, location of pathology, comorbid conditions, previous surgeries and treatments, bone quality, radiographic nuances, number of involved and symptomatic levels, etc. No literature exists to definitively support one approach over the other. We present the general trends, supported by our extensive personal experience of close to 3000 cervical surgeries.

Suppose after 4-6 weeks of conservative management for degenerative cervical myeloradiculopathy (DCM), your symptoms are no better and the numbness and weakness in your arm seems to be getting worse. You and your surgeon have decided together it is time for surgical intervention. Do you undergo an anterior approach (anterior cervical diskectomy or corpectomy with fusion and instrumentation), posterior approach (cervical laminectomies with fusion and instrumentation), or a combined anterior-posterior approach? (The details of the anterior approaches versus the posterior approach are explored in other articles on this website. This is a decision that your surgeon must frequently make; DCM is far and away the number one cause of surgical cervical spine disease the world over. Current literature unequivocally supports both anterior and posterior surgical decompression to improve neurologic functioning. Considerations and possible complications associated with anterior versus posterior approaches require further explanation before reasonable decisions can be made.

In addition to the usual complications of cervical surgery (anesthetic risks, infection, blood clots, fluid collections (seromas), allergic response to the hardware, chronic pain, delayed instability or adjacent segment disease, spinal cord or nerve root injury, hemorrhage, symptomatic pseudoarthrosis, hardware failure, etc.) the additional risks of an anterior cervical approach include but are not limited to:

  1. Dysphagia or difficulty swallowing due to swelling of the esophagus and pharynx. This usually resolves in a few days. It is best to stick with soft food that is easy to swallow for the first few days after your operation.
  2. Damage to the carotid artery or stroke. Although extremely rare, the result can be death or disabling neurologic deficit. In our practice, essentially all patients over age 40 undergo a pre- operative carotid ultrasound to rule out atherosclerotic carotid stenosis.
  3. Cerebrospinal fluid (CSF) leak. Due to damage of the dura, most leaks can be treated successfully at the time they occur to prevent the development of ongoing spinal fluid drainage (referred to as a “CSF fistula”). Persistent leaks may require treatment with reoperation or insertion of a temporary lumbar drain (a silastic tube inserted into the lumbar spine to drain CSF and take the pressure off the repair site).
  4. Dysphonia, or a hoarse voice can occur when the recurrent laryngeal nerve (RLN), a branch of the vagus nerve is stretched or damaged as a result of the surgical approach. This complication has been reported as being permanent on about 0.5% of patients; the number is much lower in our hands (0.2%). If after three months the dysphonia does not improve, various material like collagen can be injected into the affected vocal cord to improve its function. All patients with previous anterior cervical surgery should undergo consideration for a preoperative evaluation with an otolaryngologist to insure proper functioning of the vocal cords before additional surgery is attempted. Bilateral RLN palsies can be life-threatening, resulting in aspiration and difficulty breathing. In addition, we routinely monitor the RLN during surgery to avoid this complication.
  5. Horner’s syndrome. Damage to small specialized nerve fibers the run along the outside of the carotid artery can result in a droopy eyelid, an abnormally small pupil, impaired facial sweating, and a partially sunken eyeball on the same side as the injury. It is very rare and usually recovers with time.
  6. Graft or cage extrusion. Migration of the cage or graft into an adjacent vertebral body is usually minor and self –limited. Causes include poor bone quality or excessive drilling. Anterior migration is limited by the plate. Posterior migration, although exceeding rare, could result in spinal cord or nerve root compression and associated neurologic deficits, requiring revision surgery.

Generally, due to the required muscle dissection, posterior approaches result in higher blood loss, slightly higher infection rates, and more pain compared to anterior approaches.

Complications unique to posterior cervical decompression, fusion and instrumentation include but are not limited to:

Vertebral Artery Injury

Injury to the vertebral artery may occur during screw insertion laterally, resulting in pain, brainstem stroke and associated neurologic deficits, etc. This complication is more likely in patients in whom the artery takes an unusual course pre-operative MRI’s must be examined closely not only to determine spinal cord compression but to rule out an anomalous artery. Intra- operative imaging can help prevent this complication as well. See the article entitled “Image Guidance in Cervical Spine Surgery” elsewhere on wascherspineinstitute.com.

C5 Palsy

The C5 nerve root exits the spinal canal at right angles and is the cervical nerve most subject to injury with a minimum of manipulation. C5 palsy resulting in weakness of the deltoid muscle (responsible for laterally extending the arm away from the body, referred to as “abduction”), shoulder area numbness, and proximal arm pain is more common with posterior cervical approaches (as high as 5% versus 2%). It can occur in a delayed fashion (up to several days after surgery) and usually resolves spontaneously over time.

An old adage of surgery is to “first do no harm” but also “go to where the pathology resides.” In other words, a patient with anterior pathology (spinal cord compression) in most cases is best treated via an anterior approach. This provides a direct attack on the offending pathology (disc, osteophytes, and hypertrophic ligaments) with a minimum of manipulation of the spinal cord and nerve roots. Likewise, a patient with hypertrophic posterior ligaments at multiple levels producing posterior spinal cord compression is generally a candidate for posterior decompression, fusion and instrumentation. However, several complicating factors need to be taken into account.

Due to the rare but not nonexistent risk of RLN palsy, a patient whose livelihood depends on their voice (like a radio announcer or an opera singer) might be best approached posteriorly to avoid this complication.

Patients with previous neck irradiation or multiple anterior surgeries are perhaps best treated with a posterior approach to minimize the risks of anterior soft tissue, dissection of scar, and vascular injury as well as infection.

In general, an anterior approach below the C34 level is better tolerated by the usual patient than a posterior approach due to the pain caused by muscle dissection during exposure of the posterior spine. In our practice, we will attempt to provide an anterior approach if at all possible, as, in addition to the issues of less pain, it also allows us to distract across the stenotic segments and recreate normal cervical lordosis (forward curvature of the cervical spine) using lordotic cages and cervical plates; this is not possible to the same degree with a posterior approach. Distraction opens the foramina (the bony canals which the cervical nerve roots traverse on their way into the neck), decompressing the nerves to a greater degree and alleviating pain and neurologic dysfunction. Recreation of the cervical spine’s normal lordosis restores normal sagittal balance (the front-to-back balance of the cervical spine). This decreases the development of painful kyphosis (backward pathological bending of the cervical spine).

In general, high-level anterior cervical surgery (at C2-3 and C3-4) requires more extensive dissection and retraction of the soft tissues. This leads to problems with swallowing, most prominently in those over age 65. For that reason, we will tend to lean toward a posterior cervical approach for those over 65 with upper level stenosis.

Two-, three-, and higher level anterior cervical corpectomies are inherently unstable with a higher rate of post-op pseudoarthrosis (see the related article on pseudoarthrosis elsewhere on wascherspineinstitute.com. Therefore, we will always follow a multi-level corpectomy with a posterior laminectomy, fusion, and instrumentation (or at least a posterior cervical fusion and instrumentation) to maximize the chances of a successful fusion. No definite evidence exists in the literature to suggest the surgical results of anterior cervical diskectomy with fusion and instrumentation is better or worse than that associated with anterior cervical corpectomy with fusion and instrumentation. (Corpectomy refers to removal of the entire vertebral body as well as the disc spaces above and below.) However, in our experience, patients undergoing corpectomy often have greater pre-operative spinal cord compression and more advanced myelopathy. Corpectomies are indicated when the pathology extends behind the vertebral body, not just at the level of the disk space.

In cases of extremely severe spinal cord compression (compression of the anterior-posterior diameter of the cord to 5 mm or less), we have achieved recovery of neurologic function with combined anterior posterior procedures. No definitive studies exist comparing the results of anterior versus posterior decompression with fusion and instrumentation for DCM. Most authors are unable to determine any statistically significant difference in neurologic recovery rates comparing the two approaches. However, some studies point to a greater long-term improvement in quality of life with the anterior approach.

In short, the long-term results and complication rates for anterior versus posterior approaches are for the most part equivalent. The clinical presentation of the patient, along with the radiographic features, the patient’s body habitus, previous surgeries and treatments, bone quality, location of the pathology, the number of involved levels, and the patient’s comorbities all must be taken into account. The decision-making process for anterior versus posterior must be personalized and tailored to the individual needs of each and every patient. Remember, the most common cause of failed cervical spine surgery is misdiagnosis. Good outcomes with subsequent cervical surgeries diminish significantly as the number increases. You only get to make this decision for your initial cervical surgery once; make it the right one for you!

If you or a loved one has been recommended for cervical spine surgery, make certain you have the right information to make the best

decisions for your best possible outcome. Call us today at 1-855-854- 9274. We would be happy to review your MRI free of charge, and second opinions are available.

For purposes of full disclosure, we routinely publish our surgical complication rates for your review and compare them to those previously reported in the scientific literature elsewhere on wascherspineinstitute.com. We welcome any and all questions.