SUMMARY OF THE SURGICAL MANAGEMENT OF DCM
In this section of the focus issue, differing surgical options in patients with degenerative cervical conditions (cervical spondylotic myelopathy [CSM] and ossification of the posterior longitudinal ligament [OPLL]) were evaluated. During this review process, several shortcomings in the literature were readily apparent that have made the synthesis of guidelines difficult: specifically, the paucity of published well-designed studies in addition to inconsistent reporting of outcome scores.
When making the decision to treat degenerative cervical myelopathy (DCM) surgically the surgeon must decide whether to approach the patient anteriorly, posteriorly, or potentially use a combination anterior/posterior approach. In making this decision, several variables are to be considered including; ventral versus dorsal compression, sagittal alignment, focal versus diffuse disease, the presence or absence of radiculopathy or axial pain, age, comorbidities, and surgeon familiarity with each specific procedure. The complex variables that one must consider reflect the heterogeneity of clinical presentation, variable severity, and speed of progression inherent in DCM. Fortunately, in regards to OPLL, a systematic algorithm has been described that most surgeons treating OPLL adhere to1 (see Discussion in the focus article titled “Anterior versus Posterior Approaches in the Treatment of CSM: A Systematic Review”). Unfortunately, no such algorithm exists for CSM, and the remainder of this summary is an attempt to guide decision making, specifically for CSM, on the basis of the findings of this section of the focus issue in conjunction with expert opinion.
If the decision to approach multilevel cervical spondylosis anteriorly has been made, the spinal surgeon possesses an armamentarium of techniques ranging from multiple discectomies to single or multiple corpectomies and intermediary hybrid procedures, generally also requiring fusion and plate fixation as a reconstructive component. There are nonfusion alternatives, such as cervical disc arthroplasty and oblique minimally destructive corpectomies, used with the objective of avoiding fusion-related complications of adjacent segment disease and altered cervical alignment, though these alternatives remain largely unproven. Anterior techniques are more commonly used when fewer numbers of levels are involved, but may be combined with a posterior procedure, particularly in the presence of kyphosis.
Just as the patient's pathoanatomy may dictate whether a case is best approached anteriorly or posteriorly, it may similarly clarify which of the anterior surgical options one would select. These strong recommendations pertain to patients whose myelopathy is secondary to cervical spondylosis. In the absence of significant retrovertebral disease, multiple discectomies may be associated with superior neurological recovery, less neck pain, and superior correction of sagittal alignment than either corpectomy or discectomy-corpectomy hybrid approaches. In the presence of significant retrovertebral disease, discectomy-corpectomy hybrid, when possible, is favored instead of multiple corpectomies, with superior improvement in neck-related disability and superior correction of sagittal alignment.
Approach-related complications of dysphagia and infection seem similar among the various anterior cervical procedures. However, C5 palsy rates seem to be less common after procedures involving multiple discectomies compared with the corpectomy and discectomy-corpectomy hybrid options, lending further strength to the recommendation of multilevel discectomy as the preferred option.
As stated in the earlier text, there is insufficient literature to explore the utility of cervical disc arthroplasty in the management of myelopathy, with most trials hitherto exploring patients with mild myelopathy accompanying the predominant clinical presentation of radiculopathy. Among those patients, usually with 1- or 2-level disease and with mild myelopathy, the outcomes seem equivalent, but that data cannot be extrapolated to more severe myelopathy or more substantial disease with spondylotic pathology rather than soft disc compressive pathology. There are no comparative trials demonstrating the utility of oblique corpectomies, and based on the existing literature surrounding its complications, we cannot recommend its use.
When considering posterior approaches in the treatment of CSM, there are essentially 2 options that most spinal surgeons use: laminoplasty or laminectomy and fusion. Because of the high reported incidence of postlaminectomy kyphosis after laminectomy alone, this procedure is now uncommonly used,2 and therefore it is not further mentioned here. In contrast to the anterior procedures described in the earlier text, posterior procedures are generally reserved for patients with more diffused disease or spinal cord compression. Both laminoplasty and laminectomy and fusion are often used in similar circumstances. However, both of these procedures are generally avoided in patients with significant kyphosis. One of the systematic reviews included in this focus issue explores when one procedure may be preferred compared with the other. Another systematic review attempts to find factors that may predict outcomes after laminoplasty for CSM or myelopathy due to OPLL. In both reviews, building consensus statements were hampered by the low level of evidence and inconsistent reporting of outcomes and complications. Further research will be necessary to establish when one procedure is preferred instead of the other.
An alternative to either laminoplasty or laminectomy with fusion is the technique of skip laminectomy. Given the results presented in this focus issue the role of skip laminectomy remains unclear for the treatment of DCM but may be ideal in the treatment of diffuse epidural abscess formation allowing for fenestration of the posterior cervical spine while maintaining the posterior tension band and healing of muscular attachments to the posterior elements. Occasionally, combination anterior/posterior approaches are required, but this approach is generally reserved for more complex cases associated with fixed deformities and has been shown to have increased rates of dysphagia when compared with anterior or posterior approaches alone.3
Because of the heterogenous nature of DCM there are many approaches the surgeon may use when treating these patients. Although the current state of the literature surrounding the treatment of CSM is fraught with inconsistent reporting of outcomes and complications, it does seem that an individualized approach to each patient is necessary in regards to employing either an anterior or posterior approach. The most important factors to be considered include ventral versus dorsal compression, sagittal alignment, focal versus diffuse disease, the presence or absence of radiculopathy or significant spondylotic axial pain, age, comorbidities, and familiarity the surgeon has with each procedure. Please refer to the accompanying systematic reviews for the evidence-based clinical recommendations that were made for the various surgical options described in this article.
1. Iwasaki M, Okuda S, Miyauchi A, et al. Surgical strategy for cervical myelopathy
due to ossification of the posterior longitudinal ligament: Part 2: advantages of anterior decompression and fusion over laminoplasty
. Spine (Phila Pa 1976) 2007;32:654–60.
2. Kaptain GJ, Simmons NE, Replogle RE, et al. Incidence and outcome of kyphotic deformity following laminectomy
for cervical spondylotic myelopathy
. J Neurosurg 2000;93(suppl 2):199–204.
3. Fehlings MG, Smith JS, Kopjar B, et al. Perioperative and delayed complications associated with the surgical treatment of cervical spondylotic myelopathy
based on 302 patients from the AOSpine North America Cervical Spondylotic Myelopathy
Study. J Neurosurg Spine 2012;16:425–432.