Abstract
Study Design
Scoping Literature Review.
Objective
The aim of this literature review is to examine the results of both skip laminectomy and oblique corpectomy in the setting of degenerative cervical myelopathy (DCM).
Methods
A scoping review of the relevant literature examining the efficacy of cervical skip laminectomy and oblique corpectomy in patients with DCM was conducted using the Medline database. Our review strategy aimed at answering two research questions. #1: Do clinical outcomes differ between patients undergoing cervical laminoplasty vs skip laminectomy in the setting of myelopathy. #2: Which outcomes can oblique corpectomy provide, and how its related complication profile differs from other motion preserving procedures? What is the incidence of persistent myelopathy requiring reoperation following oblique corpectomy?
Results
Our query identified 43 potentially relevant articles. For questions 1, 3 were deemed relevant to the research question posed. For question 2, 6 articles were deemed relevant to the research question posed. Both cervical skip laminectomy and cervical oblique corpectomy are viable options for the treatment of DCM. Skip laminectomy compared to laminoplasty resulted in at least equivalent results in regard to functional outcomes and retained range of motion. Oblique corpectomy in appropriately indicated patients results in improved functional outcomes. It carries the unique increased risk of temporary and permanent Horner’s syndrome compared to other motion preserving cervical procedures.
Conclusion
Additional well designed comparative studies are required to draw firm conclusions in the treatment of cervical myelopathy with these alternative motion preserving techniques.
Introduction
Degenerative cervical myelopathy (DCM) is a major cause of spine-associated morbidity with an increasing prevalence coinciding with an aging population. 1 The natural course of untreated DCM is well described with limited role for conservative management in patients with progressive, symptomatic DCM. 2 Surgical intervention aims at decompressing the spinal cord and nerve roots within the cervical spinal canal and lateral foramina. Historically, surgical treatment options have included decompression with either anterior or posterior cervical fusion. Non-fusion or motion-preserving treatment options have gained popularity. Anterior cervical disc arthroplasty and posterior cervical laminoplasty are the most commonly utilized motion-preserving treatment modalities for anterior and posterior decompression, respectively; however, there are less described alternative techniques available. Among these motion-preserving treatment options are oblique corpectomy and skip laminectomy.
Surgical Techniques
Cervical Oblique Corpectomy
Cervical oblique corpectomy was first described by George et al in 1994. 3 The technique, as originally described, utilizes a lateral approach to the cervical spine, although alternative techniques using traditional Smith-Robinson approach have been proposed. 4 To be a candidate for this procedure, patient cannot have evidence of instability on cervical dynamic radiographs. In addition, the disc should be collapsed and not soft to decrease the incidence of postoperative instability. 6 For the oblique corpectomy, the patient is positioned supine. Laterality of approach is selected based on side of greatest compression and/or vertebral artery anatomy. The anterolateral vertebral body and transverse process are exposed by an approach in which the sternocleidomastoid (SCM) is taken laterally and the contents of the carotid sheath, trachea, and esophagus are protected and taken medially. The longus capitis muscle is taken laterally and the longus coli with overlying sympathetic chain is taken medially exposing the anterolateral vertebral body and transverse process. A vertical section of the vertebral body extending to the posterior longitudinal ligament (PLL) is then removed using cutting drill in an oblique angle towards the posterior aspect of the contralateral side of the vertebral body, providing anterior decompression.
Skip Laminectomy
Skip laminectomy uses a posterior approach for decompression. The procedure was first described by Shiraishi in 2002. 5 The original description is based on a four-level decompression between C3-4 and C6-7. The cephalad and caudal aspects of C4 and C6 spinous processes (SPs) are identified. These SPs are then split in the midline using a fine-tipped drill and then separated from the posterior arch while maintain their muscular attachments. The C4 and C6 laminae are then removed as are the cephalad halves of the C5 and C7 laminae. The ligamentum flavum is removed at each of these levels and from the ventral surface of the remaining laminae using curved curette and Kerrison rongeur. A decompression is achieved from C3-4 to C6-7 while leaving the SPs and their muscular attachments intact at C3, C5, and C7.
This review aims to summarize the available literature on these motion preserving surgeries in the treatment of DCM.
Methods
Our review strategy aimed at answering two research questions:
Question 1) Do clinical outcomes (functional status, revision rate, Pain, QoL score, Disability scores at greater than 6 months post-surgery, post-operative complication rate and profile) differ between patients undergoing cervical laminoplasty vs skip laminectomy in the setting of myelopathy?
Question 2) Which outcomes can oblique corpectomy provide, and how its related complication profile differs from other motion preserving procedures? What is the incidence of persistent myelopathy requiring reoperation following oblique corpectomy?
To answer these questions, a scoping review of the Medline database was performed to evaluate all published literature between September 1, 1989 through August 31, 2024. Terms searched in each database were, “(oblique corpectomy OR skip laminectomy) AND (cervical myelopathy OR cervical spondylitic myelopathy OR cervical spondylosis myelopathy).” Two investigators, JL and AA, independently reviewed all retrieved titles and abstracts for relevance. Studies reporting the outcomes or complication rates of patients undergoing cervical oblique corpectomy in the setting of myelopathy were included. Additionally, studies comparing patients with myelopathy who had undergone cervical skip laminectomy or cervical laminoplasty were included. Studies that were purely editorial, not available in English or had not been subjected to peer review were also excluded. Each reviewer independently performed full text evaluation of all potentially relevant articles to reach a consensus view on inclusion determination. Duplicate articles were removed at this step. Articles meeting inclusion criteria and answering one of the posed questions were included in this review. Discrepancies on inclusion determination at this point were settled through independent review by a fellowship trained spine surgeon, UA. Relevant studies were cross-referenced to identify articles that may have not been captured in the initial database query.
Results
Study Selection
For study questions 1, our initial database search resulted in forty-three articles. We then performed title and abstract screening, which resulted in the exclusion of thirty-nine articles. The remaining four articles underwent a full text review for eligibility. After full text review, one article was excluded secondary to duplicate data from another included work by the same author.
The three studies meeting all inclusion criteria were then described qualitatively. One study was a retrospective comparative cohort study, one a randomized controlled trial and the other a prospective non-randomized comparative cohort study. All three of these studies used institutional databases. Study duration ranged from 12 to 51.6 months, with a mean follow up of 29.1 months. The total sample size of the reported studies was 185 patients. Of these patients, 97 underwent open door laminoplasty and 88 who underwent skip-laminectomy.
For study question 2, forty-three studies were identified using the initial search parameters. After title and abstract review, thirty-two failed to meet inclusion criteria and were eliminated. Eleven studies underwent full-text review. Three of these studies were review articles and were excluded. Two studies contained duplicate data from follow-up investigations and were excluded. After these exclusions, seven articles were included for final analysis. The studies were all case series spanning from 2004 to 2014. There were 563 patients who were treated with oblique corpectomies for DCM across the included studies.
Cervical Laminoplasty vs Skip Laminectomy
Results for Question 1
Functional Outcomes/Neck Pain
All three studies reported on clinical outcomes. Shiraishi et al reported no significant differences in Japanese Orthopaedic Association (JOA) scores. Sivaraman et al found no significant differences in Short Form 12 (SF-12) scores for physical or mental health. Yukawa et al also found no significant difference in Visual Analog Scale (VAS) or JOA scores at final follow up. In assessing the amount of decompression provided by each procedure, Sivaraman et al reports no significant difference in the anteroposterior diameter obtained as evaluated on postoperative MRI. Postoperative axial neck pain was reported in all three studies. Shiraishi et al and Sivaraman et al found that patients undergoing skip laminectomy had significantly less axial neck pain compared to the patients undergoing laminoplasty, while Yukawa et al found no difference in neck pain between these treatment modalities.
Radiographic/Range of Motion Outcomes
Shiraishi et al reported that patients who underwent laminoplasty had a significant loss of lordosis compared to patients receiving skip laminectomy. However, Yukawa et al found no significant difference in cervical sagittal alignment. Cervical range of motion was assessed in all three studies. Both Shiraishi et al and Sivaraman et al found that skip laminectomy preserved more cervical motion compared to laminoplasty (98%,84% vs 44%, 46%, respectively); however no differences in cervical range of motion were observed between the two procedures by Yukawa et al.
Estimated blood Loss/Operative Time
Estimated blood loss (EBL) was examined in two of the studies, one of which reported that skip laminectomy had significantly lower EBL than laminoplasty (70 mL vs 105 mL, respectively), 14 while the other study found that there was no significant difference between the two. 13 Similarly, operative time was examined in two of the studies, one of which reported that skip laminectomy had significantly lower operative time than laminoplasty (70 min vs 108 min, respectively), 14 while the other study found that there was no significant difference between the two. 13
Oblique Corpectomy
Results for Question 2
Functional Outcomes
Chibbaro et al. has the largest published case series on oblique corpectomies in the treatment of DCM. 6 In their series of 268 patients, they report a high rate of successful treatment with 95% of patients’ JOA scores improved or remaining stable following intervention. The second largest series by Chacko et al includes 153 patients and reports similar findings. At a mean follow-up of 35.9 months, 70.4% of patients had a at least one Nurick grade improvement or more and 28.8% remained the same. 7 Only one patient progressed a Nurick grade and required an additional oblique corpectomy at a higher level. Kiris & Kilinçer report improved or stable JOA score at 6 months in 39 of 40 patients with the majority of these patients showing continued improvement in JOA score at final mean follow-up of 59 months. 8 Similar rates of clinical improvement were observed across the remaining the remaining studies.9-11
Radiographic Outcomes
Four of the six included studies assessed pre- and post-op global cervical alignment.7,8,10,11 In these studies, global alignment was assessed with lateral upright radiographs. Turel et al and Kiris & Kilinçer report no cases of development of post-operative kyphosis. Koç et al and Chacko et al report rates of developing post-operative kyphosis of 3.8% and 4.2%, respectively. 12
Signs of segmental instability were assessed with flexion-extension lateral radiographs in each of the included studies. The rate of instability following oblique corpectomies appears to be low. Only two of the studies observed cases of instability with a combined total of 8 patients.6,11
Complication Profile
The most common complication among the included studies was Horner’s syndrome. This complication was reported in all but one of the included studies. Transient Horner’s syndrome was reported at a rate between 5.2% and 30.7% with permanent signs/symptoms ranging from 1.1% to 10%.6-9,11 In the largest and longest case series, the complication rate was found to significantly decrease with increasing surgeon experience. 6 Other peri-operative complications were infrequently reported including unilateral C5 radiculopathy (8 patients), dural tear/CSF leak (4 patients), post-operative hematoma (3 patients), and vertebral artery injury (1 patient). Notably there were no reported incidences of post-operative dysphagia.
Discussion
DCM is one of the most common pathologies encountered by spine surgeons worldwide. There are a multitude of viable surgical techniques for the surgical management of this condition and the evolution of the surgical options has been remarkable. 15 Surgical procedures focusing on motion preservation have increased in volume and interest, with cervical disc arthroplasty and laminoplasty leading the way. Despite the increase in published literature on motion preservation surgery, there are limited studies comparing specific surgical techniques which preserve motion to better guide us in choosing an optimal treatment plan in patients who could benefit from a motion preserving procedure. This review summarizes the current literature as it pertains to two alternative motion-preserving surgical options for the treatment of DCM: skip laminectomy and oblique corpectomy.
Despite being first described in 2002 and 1994 respectively, there is a paucity of literature evaluating the outcomes and benefits associated with skip laminectomy and oblique corpectomy. These alternative treatment options, as shown by the results of this review, are effective in treating appropriately indicated patients with DCM. The reasons for the limited use of these techniques compared to other motion preserving techniques is not reported in the literature. This may be due to patient indications, particularly with oblique corpectomy that is limited to pathology behind the vertebral body, not involving the disc space. 16 The available data seems to agree that both provide similar long-term outcomes in the treatment of myelopathy, by halting its progression and improving myelopathic symptoms. 16
In evaluating cervical laminoplasty vs skip laminectomy, the key differences between the two seem to lie in resulting post-operative axial neck pain and cervical ROM, which favors skip laminectomy. In terms of post-operative cervical alignment, estimated blood loss and operative time, the literature is split. Two of the studies we reviewed demonstrating decreased EBL, operative time and maintained cervical alignment in the skip laminectomy groups while one of the studies report no significant difference observed in all the previously mentioned categories. While the available literature is limited, the literature suggests overall outcomes between the two procedures are similar. While the inherent biases of the articles make it challenging to draw firm conclusions, the available literature suggests skip laminectomy is a viable option for the treatment of patients with cervical myelopathy.
Due to the lack of comparative studies, it is challenging to make an inference on how oblique corpectomy would compare to other anterior-based motion preserving procedures (eg, cervical disc arthroplasty). According to the limited data, cervical myelopathy in appropriately indicated patients has favorable outcomes utilizing oblique corpectomy. This is however at the risk of a unique complication. Horner’s syndrome is uncommon in traditional anterior based approaches, with a reported rate in Fountas et al of 0.1%. This is in stark contrast to oblique corpectomy, with a transient rate reported as high as 30% and permanent rate as high as 10%.8,11 This is most certainly secondary to the surgical plane, which requires an approach starting lateral to the carotid sheath. With this technique, the sympathetic chain is in the surgical field lying on the longus coli muscle. There is debate concerning dissection of the sympathetic chain during the surgical approach. Chibbaro et al in 2009 advised against it, and their recent review of the literature confirmed that sympathetic chain dissection increases perioperative risks without a clear advantage in terms of preparation of the surgical corridor to access the spinal canal. 16 However, others report that by adopting the operative modification of making a longitudinal incision in the longus coli sheath and retracting the sympathetic chain medially, there is a further reduction in the incidence of Horner’s syndrome in their limited study. It has been demonstrated that the rate of Horner’s syndrome decreases with experience. Given the paucity of literature, this complication is the most likely reason the technique never gained popularity.
Limitation of the Study
This study has several limitations. The study design limits the application of this study’s finding to clinical practice. While the research questions and objectives are in line with a systematic review, a scoping review was performed to broadly map the existing literature on the topic due to the paucity of well-designed studies available for review. There was not an adequate amount of data present to critically analyze the research questions we sought to answer. Additionally, the limited data available has significant bias that affect strong inferences to be concluded. The studies on oblique corpectomy lack a control/comparative group. This however is likely due to the patient indications, which are dissimilar from other motion preserving treatment options from an anterior based approach that address pathology at the level of the disc. Additional well designed comparative studies are required to draw firm conclusions in the treatment of cervical myelopathy with these alternative motion preserving techniques.
Conclusion
Our results indicate that cervical skip laminectomy and cervical oblique corpectomy are both viable options for tailored surgical management of DCM, with the caveat that careful patient selection is of paramount importance to attain satisfactory results. In fact, skip laminectomy compared to laminoplasty resulted in at least equivalent results in regard to functional outcomes and retained range of motion. Oblique corpectomy in appropriately indicated patients results in improved functional outcomes but carries the unique risk of increased transient and permanent Horner’s syndrome, which is dissimilar compared to other motion preserving cervical procedures.
Additional well-designed comparative studies are certainly required to draw firm conclusions in the treatment of DCM and appraise the long-term outcomes of these alternative motion-preserving techniques.
Footnotes
ORCID iDs
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This supplement was organized and financially supported by AO Spine through the AO Spine Knowledge Forum Spinal Cord Injury, a focused group of international spine experts, and AO Spine North America. AO Spine is a clinical division of the AO Foundation, which is an independent medically-guided not-for-profit organization based in Davos, Switzerland.