Surgical Management of Cervical Ossification of the Posterior Longitudinal Ligament: Natural History and the Role of Surgical Decompression and Stabilization

Neurosurg Focus 30 (3):E3, 2011

Surgical management of cervical ossification of the posterior longitudinal ligament: natural history and the role of surgical decompression and stabilization

Patrick A. Sugrue, M.D., Jamal McClendon Jr., M.D., Ryan J. Halpin, M.D., John C. Liu, M.D., Tyler R. Koski, M.D., and Aruna Ganju, M.D. Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois

Object. Ossification of the posterior longitudinal ligament (OPLL) is a complex multifactorial disease process combining both metabolic and biomechanical factors. The role for surgical intervention and choice of anterior or posterior approach is controversial. The object of this study was to review the literature and present a single-institution experience with surgical intervention for OPLL. Methods. The authors performed a retrospective review of their institutional experience with surgical intervention for cervical OPLL. They also reviewed the English-language literature regarding the epidemiology, pathophysi- ology, natural history, and surgical intervention for OPLL. Results. Review of the literature suggests an improved benefit for anterior decompression and stabilization or posterior decompression and stabilization compared with posterior decompression via laminectomy or laminoplasty. Both anterior and posterior approaches are safe and effective means of decompression of cervical stenosis in the setting of OPLL. Conclusions. Anterior cervical decompression and reconstruction is a safe and appropriate treatment for cervical spondylitic myelopathy in the setting of OPLL. For patients with maintained cervical lordosis, posterior cervical decompression and stabilization is advocated. The use of laminectomy or laminoplasty is indicated in patients with preserved cervical lordosis and less than 60% of the spinal canal occupied by calcified ligament in a “hill-shaped” contour. (DOI: 10.3171/2010.12.FOCUS10283)

Key Words • cervical stenosis • cervical spondylitic myelopathy • ossification of the posterior longitudinal ligament • laminoplasty • corpectomy

ssification of the posterior longitudinal ligament various types of OPLL in the cervical spine and the advan- (OPLL) is a pathological process whereby the PLL tages and disadvantages of different surgical strategies as becomes progressively calcified, often leading to supported by our institutional experience. symptomaticO spinal canal or foraminal stenosis.11,29,31 It is The prevalence of OPLL has been shown to be high- a complex disease process, and patients often present to er in East Asian countries, most significantly in Japan the spine surgeon in an advanced stage requiring surgical (1.9%–4.3%), Korea (3.6%), and Taiwan (2.8%).11 The intervention. There is a great deal of evidence that OPLL prevalence of OPLL in the North American Caucasian is a multifactorial process resulting not only from inherent population has been reported as only 0.12% historically,11 biological factors but also from environmental and biome- but more recently, Epstein5 has reported that as many as chanical factors.11,29,30,33 Each of these competing factors 25% of patients who present with cervical myelopathy plays a role in the natural history of the disease process and have some evidence of OPLL. While there is evidence of ultimately in the role of surgical intervention. With that in a genetic predisposition for OPLL there are also underly- mind, there are various potential surgical options available ing associated metabolic comorbidities. Both adult-onset to the spine surgeon, each with its own risks, benefits, and and non–insulin-dependent diabetes mellitus have been accompanying pitfalls. In this manuscript, we discuss the shown to be independent risk factors for OPLL and are believed to be related to an increase in insulin produc- Abbreviations used in this paper: BMP = bone morphogenetic tion and its upregulating effect on osteoprogenitor cells 1,11,20,27 protein; DISH = diffuse idiopathic skeletal hyperostosis; JOA = leading to OPLL. Ossification of the PLL can also Japanese Orthopaedic Association; OPLL = ossification of the PLL; be seen in as many as 50% of cases of diffuse idiopathic PLL = posterior longitudinal ligament. skeletal hyperostosis (DISH).5,7

Neurosurg Focus / Volume 30 / March 2011 1

Unauthenticated | Downloaded 09/26/21 11:47 PM UTC P. A. Sugrue et al.

Four types of OPLL have classically been de- patients who have few neurological symptoms or for those scribed:10,25 1) segmental—confined to the area posterior whose overall medical health precludes them from surgi- to the vertebral bodies without crossing the disc spaces; cal treatment. Pharmacological pain management with 2) continuous—extending from vertebral body to verte- the guidance of multidisciplinary pain specialists is rec- bral body including the disc space and spanning multiple ommended. Nonsteroidal antiinflammatory medications levels; 3) mixed: combined aspects of both segmental and and steroid injections are the mainstays of nonoperative continuous types that maintains some skipped areas; and therapy. Unfortunately, despite the inflammatory nature 4) other: limited to area behind the disc space with some of the disease, there have been few pharmacological ad- extension to the posterior vertebral body endplate or focal vances in the specific antiinflammatory agents designed punctate areas of hypertrophy/calcification of the poste- for OPLL, as compared with other inflammatory disease rior longitudinal ligament. such as rheumatoid arthritis or ankylosing spondylitis. Although OPLL is the result of multiple processes, Nearly 70% of cases of OPLL involve the cervical there have been numerous studies addressing the genetic spine.5 Most patients with cervical OPLL come to the at- and metabolic basis of this disease. While the details of tention of spine surgeons because of clinical findings of those studies are beyond the scope of this manuscript, myelopathy, radiculopathy, or both and thus require surgi- there are a few details that bear mentioning. The role of cal intervention. The questions that often face the surgeon repeated mechanical stress to the cervical spine has been involve the appropriate surgical approach: anterior versus proposed as an agent in the formation of OPLL. Stud- posterior and decompression alone versus decompression ies looking at the importance of dynamic repeated stress and stabilization. The location of the OPLL, in conjunction have demonstrated an increase in BMP-2, BMP-4, prosta- with the patient’s clinical symptoms, guides the surgeon in glandin I2 synthase, and osteoblast specific transcription formulating a surgical plan. There are different treatment factors in patients with OPLL compared with those with- options available for OPLL of the cervical spine, compared out OPLL.11,12 The increase in these cytokines suggests, with OPLL of the thoracic or lumbar spine. In the cervical as the authors point out, that the mechanical stress in- spine, the anterior spinal column is much more accessible duces a biochemical response that leads ultimately to os- and often carries less morbidity than the thoracotomy that teogenic induction in the ligament cells leading to OPLL. would be required for anterior access to the thoracic spine. The importance of this finding with respect to surgical in- Many patients with OPLL harbor other medical comorbid- tervention is important to point out in terms of the role of ities or are of advanced age such that thoracotomy is not an surgical stabilization as opposed to decompression alone. ideal choice. On the other hand, older patients undergoing Matsunagra et al.22 studied the natural history of un- multilevel cervical corpectomy have been shown to have treated OPLL and found that 17% of patients who were an increased rate of significant dysphagia postoperatively. found to have OPLL without signs of myelopathy went on Posterior decompression via laminectomy or laminoplasty to progress to the development of myelopathy. Likewise, is an option at any level of the spine. The need for stabiliza- 64% of patients with signs of myelopathy at the time of pre- tion is often greater in the cervical spine than in the tho- sentation who did not undergo surgery experienced neuro- racic spine, the latter being supported by the thoracic cage. logical deterioration. This clinical study helps to highlight However, kyphosis of the thoracic spine may increase the the fact that the development and progression of OPLL is need for instrumented stabilization to minimize the risk a dynamic process. Epstein5 describes OPLL as part of a of a progressive kyphotic deformity in the setting of a dis- continuum that begins with increased vascular fibrosis of rupted posterior tension band. There are many factors that the PLL and progresses to focal calcification, proliferation influence the surgical plan for OPLL, and in this manu- of periosteal cartilage, and ultimately ossification. Early script we analyze our single-institution experience with ossification is often seen in patients in the 5th decade of surgically treated cervical OPLL. life in the area posterior to the disc space alone, making it difficult to distinguish from degenerative spondylosis. The rate of ossification is variable among different patient Methods 8 groups but Harsh et al. found an annual growth rate of After obtaining institutional review board approval, 0.67 mm in the anterior-posterior direction and 4.1 mm we retrospectively analyzed our own patient experience in the cranial-caudal direction. In another study, Matsu- 21 with cervical OPLL. Individual surgeon case logs and naga et al. confirmed these findings, demonstrating that billing records were reviewed for the previous 10 years nearly 20% of patients with untreated OPLL experienced (2000–2010). We retrospectively identified 18 patients an increase of 2 mm or more in PLL thickness and 86% (Table 1) who underwent surgery for symptomatic cer- experienced an increase in the cranial-caudal extent of the 26 vical myelopathy secondary to radiographically con- disease. Murakami et al. likewise report a case of a pa- firmed OPLL. The different types of OPLL as classified tient who progressed from asymptomatic segmental OPLL by Hirabayashi et al.10 were evenly distributed among our to a mixed-type OPLL as his neurological condition dete- patients: continuous in 6, segmental in 6, and mixed in riorated, developing myelopathy over the course of 4 years. 6. Twelve patients underwent laminectomy and instru- The progressive nature of OPLL suggests that most patient mented stabilization (Figs. 1 and 2), 3 patients underwent will ultimately require some sort of surgical intervention. 2-level corpectomy, 2 patients underwent 1-level corpec- Surgical Management tomy (Figs. 3 and 4), and 1 patient underwent 1-level corpectomy with adjacent-level anterior cervical discectomy Nonoperative management of OPLL is reserved for and fusion. Medical record chart review was performed

2 Neurosurg Focus / Volume 30 / March 2011 Unauthenticated | Downloaded 09/26/21 11:47 PM UTC Surgical management of cervical OPLL

TABLE 1: Summary of demographic and clinical characteristics in 18 patients*

Case Age (yrs), Type of No. Sex OPLL† Procedure 1 62, F continuous C5–6 corpectomy, C4–7 ASF 2 60, M continuous C5–6 corpectomy, C4–7 ASF 3 51, F continuous C-4 corpectomy, C5–6 ACD, C3–6 ASF 4 79, M continuous C-5 corpectomy, C4–6 ASF 5 59, F continuous C3–7 laminectomy, C3–T2 PSF 6 86, M continuous C4–7 laminectomy, C3–T2 PSF 7 58, M mixed C3–6 laminectomy, C3–6 PSF 8 84, M mixed C3–5 laminectomy, C3–5 PSF 9 74, M mixed C3–7 laminectomy, C3–T2 PSF 10 59, M mixed C4–7 laminectomy, C4–T2 PSF Fig. 2. Case 5. Postoperative images. Anterior-posterior (left) and 11 51, F mixed C3–6 laminectomy, C3–6 PSF lateral (right) radiographs obtained after C3–7 laminectomy and C3–T2 12 42, M mixed C4–6 laminectomy, C3–T2 PSF instrumented posterior spinal fusion. 13 31, F segmental C-6 corpectomy, C5–7 ASF 14 64, F segmental C3–7 laminectomy, C3–7 PSF tient suffered a massive pulmonary embolus 1 month after surgery and died as a result. In another case, there 15 68, F segmental C3–6 laminectomy, C3–7 PSF was no record of the patient’s ever returning to clinic af- 16 56, M segmental C3–5 laminectomy, C3–T2 PSF ter discharge and the patient was thus classified as lost 17 42, F segmental C5–6 corpectomy, C4–7 ASF to follow-up. Of the 16 patients for whom follow-up data 18 54, M segmental C3–7 laminectomy, C3–7 PSF were available, 31% demonstrated a significant improvement in strength on objective physical examination; 69% * There was no CSF leak or postoperative neurological deficit. Abbre- remained neurologically stable; and 12.5% experienced viations: ACD = anterior cervical discectomy; ASF = anterior spinal fu- some transient weakness in 1 or more muscle groups dur- sion; PSF = posterior spinal fusion. ing the immediate postoperative period. The average du- † As classified by Hirabayashi et al. ration of follow-up was 9 months (range 1–36 months). There was no radiographic evidence of instrumentation to obtain both preoperative and postoperative neurologi- loosening or failure in the short term for any patients 3 cal examination status as well as presenting complaints. months after surgery. There was no evidence of CSF leak. The type of procedure was recorded as well as findings of pre- and postoperative neurological examinations and Discussion follow-up imaging. Any intraoperative or postoperative complications documented in the medical record were When evaluating patients with OPLL, preoperative also recorded. The average follow-up time was calcu- planning is essential. Careful assessment of the imaging lated. Any change in neurological examination findings studies includes determining the extent of ossification documented in the medical record was recorded. and the direction of the surgical approach (anterior vs posterior). Diagnostic imaging in OPLL is usually multi- Results modality. Typically, when patients present for neurosurgi- cal evaluation, an MR imaging study has already been Follow-up data were available in 16 cases. One pa- performed for evaluation of neck pain or arm pain. The

Fig. 1. Case 5. Preoperative images. This 59-year-old woman was found to have cervical spondylitic myelopathy and OPLL. A: Sagittal CT reconstruction demonstrating continuous OPLL at the C4–6 levels. B and C: Axial CT images reveal- ing severe spinal canal stenosis due to OPLL at multiple levels. There is also evidence of DISH on the sagittal and axial images.

Neurosurg Focus / Volume 30 / March 2011 3 Unauthenticated | Downloaded 09/26/21 11:47 PM UTC P. A. Sugrue et al.

Fig. 3. Case 4. Preoperative images. This 79-year-old man with gait difficulties was found to have cervical spondylitic myelopathy secondary to continuous OPLL as seen on sagittal T2-weighted MR imaging (A), sagittal CT reconstruction (B), and axial CT (C). appearance of OPLL on MR imaging differs depending gression of untreated OPLL we advocate for early surgi- on the extent of progression of the ossification process. cal intervention. For example, early OPLL is often confined to the area Computed tomography can help to confirm OPLL first behind the disc space with some extension to the adja- suspected on MR imaging; CT can often help to better de- cent vertebral bodies or end plates; in such a case, OPLL fine the extent of disease seen on MR imaging and identify appears very similar to spondylosis or disc herniation. any foraminal component or the degree of stenosis. Like- Hypertrophied and calcified ligament appears hypoin- wise, OPLL in its early stages may be missed on CT sagit- tense on unenhanced MR images, but following the ad- tal reconstructions and these images should be correlated ministration of gadolinium, ossified PLL enhances. Disc with axial imaging. Ossification of the ligamentum flavum herniations do not enhance. In fact, particularly advanced can also be associated with OPLL and can be seen best on cases of OPLL will display evidence of fat deposition and CT. 5 The longitudinal extent and circumferential location signs of bone marrow production. Advanced continuous of both anterior and posterior ossification and subsequent OPLL may demonstrate the development of a Haversian canal or foraminal stenosis aid in formulating the appropri- canal system within the calcified ligament.5 Wang et al.34 ate surgical plan. CT myelography often helps to define the studied T2 signal intensity ratios between intramedullary extent of spinal cord compression and the urgency of surgi- areas posterior to compressive ossified PLL compared cal intervention. Dynamic flexion-extension imaging can with the intramedullary signal behind the C7–T1 disc also play a role when the surgeon is considering stabiliza- space where there was no compression in patients with tion. It is important to point out the importance of utilizing myelopathy prior to laminoplasty. They concluded that CT reconstructions in assessing OPLL to best understand patients with low signal-intensity ratios had better surgi- the 3D anatomy of the disease. Chang et al.2 have dem- cal outcomes than those with high signal-intensity ratios onstrated the increased intra- and interobserver reliability and evidence of pyramidal signs.34 Given the likely pro- of CT reconstructions compared with plain radiographs or even axial CT alone. Patient age and medical comorbidities also influence the decision to use an anterior or posterior approach and whether to perform stabilization. Epstein5 reports that in comparison to stand-alone posterior procedures, anterior procedures produce better short- and long-term improvement in neurological outcomes. The work of Kawano et al.18 provides support for this notion, demonstrating improved outcomes in the short-term and long-term for patients undergoing anterior corpectomy compared with those undergoing posterior procedures. Anterior decompression of the spine seems to be the definitive surgical approach for a compressive lesion ventral to the spinal cord. However, OPLL can often present as segmental or continuous type of lesion spanning multiple levels. Good results have been reported for 1- and 2-level cervical corpectomies; however, corpectomies of 3 levels or more are fraught with complications including graft fracture, graft pistoning, graft dis- 4 Fig. 4. Case 4. Postoperative images. Anterior-posterior (left) and lodgement, instrumentation failure, and pseudarthrosis. lateral (right) radiographs obtained after C-5 corpectomy and C4–6 Dalbayrak et al.4 have introduced the idea of the “skip” anterior spinal fusion. corpectomy, whereby the C-5 vertebral body is left intact

4 Neurosurg Focus / Volume 30 / March 2011 Unauthenticated | Downloaded 09/26/21 11:47 PM UTC Surgical management of cervical OPLL and C-4 and C-6 corpectomies are performed for cervical lordosis. In particular, patients who lack cervical lordosis spondylitic myelopathy and OPLL. They conclude that the may benefit from an anterior approach when possible. In C-5 body adds additional stability to the anterior cervical cases in which posterior decompression is required, how- construct and the procedure still provides adequate decom- ever, we typically perform a stabilization procedure in our pression. The biomechanical complications are compound- institution due to concern about progression of OPLL as a ed by high rates of postoperative dysphagia in patients who result of dynamic instability or progression of sagittal de- have undergone multilevel cervical corpectomy. formity. Posterior decompression alone has been shown Anterior corpectomy has been shown to have sig- to accelerate progression of OPLL ventrally. Takatsu et nificant benefits for these patients, but many surgeons are al.32 demonstrated an increase in the rate of deteriora- concerned about the risk of durotomy and postoperative tion of patients who underwent posterior decompression CSF leak due to the adherent ossified PLL and the poten- alone—laminectomy or laminoplasty—compared with tial for continued neurological deterioration due to insuf- those who did not undergo any surgical intervention for ficient decompression.3,6,23,28,35 In the series reported by OPLL. Likewise, when the decompression extends to the Chen et al.,3 only 4 patients suffered a CSF leak, and there cervical-thoracic junction, stabilization should extend was no evidence of neurological decline in patients who across the cervical-thoracic junction to T-2 to minimize underwent anterior corpectomy. The authors conclude that the risk of a junctional kyphosis. these outcomes are the result of a lack of traumatic ma- In the US, most cases of OPLL are treated using a nipulation of the spinal cord and protection of the epidural posterior approach, as it can be a less technically than vascular plexus. They used specially designed microdis- an anterior corpectomy. However, the need for posteri- sectors to separate the ossified PLL from the dura and they or stabilization is controversial. Laminoplasty has been also used the popular “floating” technique when there was used to achieve posterior decompression while preserv- evidence of dural ossification. Hida et al.9 studied the CT ing motion, but patients with a straight or kyphotic cervi- characteristics of patients with OPLL and demonstrated cal spine are at risk for progression of cervical kyphosis, some key findings that help determine the amount of du- and laminoplasty is contraindicated in this population. ral ossification and thus the potential risk of durotomy and Patients with reversal of cervical lordosis who undergo CSF leak at the time of surgery. They studied 21 patients laminoplasty have been shown to experience progression with radiographic evidence of OPLL and correlated their of kyphotic deformity as well as progression of ligamen- findings with intraoperative evidence of dural defect. They tous ossification postoperatively.3,13,17,22 describe double- and single-layer OPLL. Twelve patients Laminectomy without stabilization or laminoplasty were found to have a double layer of ossification on CT at can be an effective surgical option in specific circum- the level of the thickest ossified PLL and 10 patients were stances. Iwasaki et al.14,15 have studied long-term out- found to have a single calcified layer. Of the 12 patients comes in patients who underwent cervical laminoplasty with double-layer OPLL, 10 of them were found to have for OPLL and concluded that the most significant pre- dural defects, whereas 9 of the 10 patients with single-layer dictors for poor neurological outcome following lamino- OPLL had intact dura.9 Utilizing these findings on preop- plasty are “hill-shaped” ossification, lower preoperative erative CT can help determine which areas of the ossified JOA score, postoperative change in cervical alignment, PLL should be left in place at surgery. In our experience, and older age at time or surgery. Likewise, they report calcified ligament can be removed safely. When remov- worse neurological outcomes for patients with an occupy- ing the calcified ligament, one must be careful to dissect ing ratio of 60% or greater. in the appropriate plane. That plane can often be found by Matz et al.24 performed a detailed analysis of the lit- sliding a blunt nerve hook under the lateral aspect of the erature and concluded that there is Class III evidence to ligament. Utilizing the appropriate plane minimizes the support the use of laminoplasty in cervical spondylitic risk of neurological injury, CSF leak, and injury to the en- myelopathy or OPLL. They report 55%–60% JOA score gorged epidural venous system. In the event that the liga- improvement compared with nonoperative therapy. Fur- ment is adherent to the dura, certain “bone islands” can be thermore, while the most common complication of lami- left in place. If the area of adherent calcified ligament is noplasty is the development of a C-5 nerve palsy due to totally disconnected circumferentially, then it is unlikely cord shift and nerve root stretch, there is preserved range to impose any compression on the spinal cord. Repair of of motion and Class III evidence of equivalence in func- an anterior durotomy can be challenging, particularly in tional improvement between laminoplasty, anterior cer- the setting of calcified dura. If a CSF leak occurs it should vical decompression and fusion, and laminectomy with be repaired immediately. If CSF drains from the thecal arthrodesis.24 For our patient population, laminoplasty sac, the engorged epidural venous plexus will likely bleed or laminectomy alone are rarely used due to the concern significantly, making the procedure even more technically about progression of OPLL or development of cervical challenging. kyphosis. Many patients with OPLL also have DISH. The Although in our experience anterior decompression combination of OPLL and DISH may provide some ante- and reconstruction can be done effectively and safely for rior stability to the construct and thus reduce the risk of 2-level disease, 3-level corpectomies are often not well developing progressive kyphosis in the setting of lamino- tolerated due to postoperative dysphagia as well as the plasty or laminectomy. However, we have not had that ex- biomechanical challenges of such a large construct. With perience at our institution, and thus all patients with mul- that in mind, we find that the most important factor in tilevel cervical decompression in the setting of a straight choosing an anterior or posterior approach is cervical or kyphotic cervical spine also undergo stabilization.

Neurosurg Focus / Volume 30 / March 2011 5 Unauthenticated | Downloaded 09/26/21 11:47 PM UTC P. A. Sugrue et al.

The technique we employ for posterior cervical de- kyphotic deformity. The fact that some of the patients in compression typically involves an en bloc laminectomy. the laminoplasty group experienced worsening neurologi- Using a high-speed drill, bilateral troughs are created cal deficits helps support the idea that there is indeed an at the junction of the lamina and lateral mass or lami- impact from a repeated mechanical stress and potential in- na-facet line, thus releasing the lamina from the lateral stability that may contribute to development of OPLL. The mass. Once the troughs are drilled, a nerve hook is used patients in this study who underwent instrumented stabili- to define the epidural space. Disconnection of the osteo- zation did not suffer the same neurological decline. Wheth- ligamentous structures is performed by using Kerrison er the deterioration was from progressive kyphosis or from punches to systematically complete the disassociation of OPLL progression is not completely clear, but may be due lamina from the facets. Similarly, disconnection of the to both processes leading to continued or worsening steno- osteoligamentous structures must also be performed at sis/compression. Although the literature suggests improved the cephalad and caudal ends to remove the lamina en outcomes for anterior decompression and reconstruction, bloc. This process of removing the ligamentum flavum both groups of patients in our series who underwent ante- must be done carefully to avoid any tearing of the dura. rior or posterior procedures did well neurologically. The Both the ligamentum and the dura may be calcified or decision to use an anterior or posterior approach was based adherent to one another. The lamina can later be used as on the number of levels involved, cervical lordosis, medical autograft for fusion. Throughout the procedure, the mean comorbidities, and patient age. arterial blood pressure is maintained above 80 mm Hg to provide appropriate spinal cord perfusion. Instrumenta- Conclusions tion is typically placed prior to decompression using a modified Magerl technique16 for placement of lateral mass Ossification of the PLL is a complex multifactorial fixation and the free-hand technique described by Lenke19 disease process that requires an understanding of the eti- is used for thoracic pedicle screw placement when neces- ology of the disease as well as the role for surgical in- sary. Complete arthrodesis of the facet complex is essen- tervention. Most patients who present with symptomatic tial to optimize fusion. The use of osteobiologic agents OPLL will eventually require surgery. The natural histo- is a controversial topic and is left to the discretion of the ry of OPLL is that of progressive neurological decline re- surgeon. While osteobiologics can enhance fusion rates sulting from enlargement of the ossified ligament and re- in the posterior cervical spine, their use in the anterior sulting stenosis. Clinical myelopathy is further worsened cervical spine is not recommended due to the intense by a dynamic process whereby mechanical stress is trans- inflammatory response generated and the concern for ferred into reactive inflammation. The role of surgery is compromising the patient’s airway. The fusion rate in our to decompress and stabilize the spine. For patients who case series is high and likely on a par with other institu- demonstrate appropriate lordosis, laminoplasty or lami- tions’ series in large part due to the inflammatory nature nectomy may be a viable option. However, studies suggest of OPLL and high propensity for calcification and fusion. that despite preservation of cervical lordosis, patients with Overall, the decision to use an anterior or posterior myelopathy secondary to OPLL require stabilization. The approach is a complicated one involving many factors. In decision to use an anterior or posterior approach is left to our series, 67% of the patients underwent posterior decom- the discretion of the surgeon. Both anterior and posterior pression and fusion. Posterior stabilization is often a less approaches have been shown to be safe and effective in technically demanding procedure that can be done safely our experience. Due to the ability to create lordosis in the and effectively. Chen et al.3 retrospectively studied radio- cervical spine, outcomes from anterior decompression graphic and clinical outcomes in 75 patients with severe and reconstruction have been shown in the literature to be OPLL as defined by 3 or more levels of OPLL with at least superior to the posterior decompression and stabilization. a 40% compromise of the cervical canal. The patients We have demonstrated successful decompression and fu- underwent anterior corpectomy and reconstruction, lami- sion from both an anterior and a posterior approach. The nectomy and posterior instrumented stabilization, or lami- choice of which approach to use is based on a number of noplasty. In this study they demonstrated a few important factors that influence patient outcomes. points. First, patients who underwent anterior corpectomy Disclosure or laminectomy and instrumentation maintained a significantly greater cervical lordosis compared with those who The authors report no conflict of interest concerning the mate- underwent laminoplasty. Also, Chen et al.3 demonstrated rials or methods used in this study or the findings specified in this that neurological improvement measured by the JOA scale paper. was significantly greater in patients who underwent anteri- Author contributions to the study and manuscript preparation include the following. Conception and design: Sugrue, McClendon, or corpectomy than in those who underwent laminoplasty. Liu, Koski, Ganju. Acquisition of data: Sugrue, McClendon. For example, the mean JOA improvement percentage (± Analysis and interpretation of data: Sugrue, McClendon. Drafting SD) for those in the 3 groups was as follows: anterior cor- the article: Sugrue, McClendon. Critically revising the article: all pectomy 63.2 ± 15.2, laminectomy and stabilization 43.5 authors. Reviewed final version of the manuscript and approved it ± 12.7, and laminoplasty 25.1 ± 8.5. None of the patients for submission: all authors. in the anterior corpectomy group or the laminectomy and fusion group experienced neurological deterioration post- References operatively, but 4 of 25 patients who underwent lamino- 1. Akune T, Ogata N, Seichi A, Ohnishi I, Nakamura K, Kawagu- plasty suffered neurological deterioration and progressive chi H: Insulin secretory response is positively associated with

6 Neurosurg Focus / Volume 30 / March 2011 Unauthenticated | Downloaded 09/26/21 11:47 PM UTC Surgical management of cervical OPLL

the extent of ossification of the posterior longitudinal ligament terior longitudinal ligament of the spine in Japanese subjects: a of the spine. J Bone Joint Surg Am 83-A:1537–1544, 2001 case-control study in multiple hospitals. Spine 29:1006–1010, 2. Chang H, Kong CG, Won HY, Kim JH, Park JB: Inter- and 2004 intra-observer variability of a cervical OPLL classification us- 21. Matsunaga S, Kukita M, Hayashi K, Shinkura R, Koriyama C, ing reconstructed CT images. Clin Orthop Surg 2:8–12, 2010 Sakou T, et al: Pathogenesis of myelopathy in patients with os- 3. Chen Y, Guo Y, Lu X, Chen D, Song D, Shi J, et al: Surgical sification of the posterior longitudinal ligament. J Neurosurg strategy for multilevel severe ossification of posterior longi- 96 (2 Suppl):168–172, 2002 tudinal ligament in the cervical spine. J Spinal Disord Tech 22. Matsunaga S, Sakou T, Taketomi E, Komiya S: Clinical course [epub ahead of print], 2010 of patients with ossification of the posterior longitudinal liga- 4. Dalbayrak S, Yilmaz M, Naderi S: “Skip” corpectomy in the ment: a minimum 10-year cohort study. J Neurosurg 100 (3 treatment of multilevel cervical spondylotic myelopathy and Suppl Spine):245–248, 2004 ossified posterior longitudinal ligament. Technical note. J 23. Matsuoka T, Yamaura I, Kurosa Y, Nakai O, Shindo S, Shi- Neurosurg Spine 12:33–38, 2010 nomiya K: Long-term results of the anterior floating method 5. Epstein N: Ossification of the cervical posterior longitudinal for cervical myelopathy caused by ossification of the posterior ligament: a review. Neurosurg Focus 13(2):ECP1, 2002 longitudinal ligament. Spine 26:241–248, 2001 6. Epstein N: The surgical management of ossification of the 24. Matz PG, Anderson PA, Groff MW, Heary RF, Holly LT, Kai- posterior longitudinal ligament in 51 patients. J Spinal Dis- ser MG, et al: Cervical laminoplasty for the treatment of cer- ord 6:432–455, 1993 vical degenerative myelopathy. J Neurosurg Spine 11:157– 7. Epstein NE: Simultaneous cervical diffuse idiopathic skel- 169, 2009 etal hyperostosis and ossification of the posterior longitudinal 25. Morimoto T, Matsuyama T, Hirabayashi H, Sakaki T, Yabuno ligament resulting in dysphagia or myelopathy in two geriatric T: Expansive laminoplasty for multilevel cervical OPLL. J North Americans. Surg Neurol 53:427–431, 2000 Spinal Disord 10:296–298, 1997 8. Harsh GR IV, Sypert GW, Weinstein PR, Ross DA, Wilson CB: 26. Murakami M, Seichi A, Chikuda H, Takeshita K, Nakamura Cervical spine stenosis secondary to ossification of the poste- K, Kimura A: Long-term follow-up of the progression of os- rior longitudinal ligament. J Neurosurg 67:349–357, 1987 sification of the posterior longitudinal ligament. Case report. 9. Hida K, Iwasaki Y, Koyanagi I, Abe H: Bone window comput- J Neurosurg Spine 12:577–579, 2010 ed tomography for detection of dural defect associated with 27. Okamoto K, Kobashi G, Washio M, Sasaki S, Yokoyama T, cervical ossified posterior longitudinal ligament.Neurol Med Miyake Y, et al: Dietary habits and risk of ossification of the posterior longitudinal ligaments of the spine (OPLL); findings Chir (Tokyo) 37:173–176, 1997 from a case-control study in Japan. J Bone Miner Metab 22: 10. Hirabayashi K, Watanabe K, Wakano K, Suzuki N, Satomi K, 612–617, 2004 Ishii Y: Expansive open-door laminoplasty for cervical spinal 28. Onari K, Akiyama N, Kondo S, Toguchi A, Mihara H, Tsuchi- stenotic myelopathy. Spine 8:693–699, 1983 ya T: Long-term follow-up results of anterior interbody fusion 11. Inamasu J, Guiot BH, Sachs DC: Ossification of the posterior applied for cervical myelopathy due to ossification of the pos- longitudinal ligament: an update on its biology, epidemiology, terior longitudinal ligament. Spine 26:488–493, 2001 and natural history. Neurosurgery 58:1027–1039, 2006 29. Sakou T, Matsunaga S, Koga H: Recent progress in the study 12. Iwasaki K, Furukawa KI, Tanno M, Kusumi T, Ueyama K, of pathogenesis of ossification of the posterior longitudinal Tanaka M, et al: Uni-axial cyclic stretch induces Cbfa1 ex- ligament. J Orthop Sci 5:310–315, 2000 pression in spinal ligament cells derived from patients with 30. Sakou T, Taketomi E, Matsunaga S, Yamaguchi M, Sonoda S, Calcif Tis- ossification of the posterior longitudinal ligament. Yashiki S: Genetic study of ossification of the posterior longi- sue Int 74: 448–457, 2004 tudinal ligament in the cervical spine with human leukocyte 13. Iwasaki M, Kawaguchi Y, Kimura T, Yonenobu K: Long-term antigen haplotype. Spine 16:1249–1252, 1991 results of expansive laminoplasty for ossification of the pos- 31. Schmidt MH, Quinones-Hinojosa A, Rosenberg WS: Cervi- terior longitudinal ligament of the cervical spine: more than cal myelopathy associated with degenerative spine disease J Neurosurg 96 (2 Suppl): 10 years follow up. 180–189, 2002 and ossification of the posterior longitudinal ligament.Semin 14. Iwasaki M, Okuda S, Miyauchi A, Sakaura H, Mukai Y, Yo- Neurol 22:143–148, 2002 nenobu K, et al: Surgical strategy for cervical myelopathy 32. Takatsu T, Ishida Y, Suzuki K, Inoue H: Radiological study of due to ossification of the posterior longitudinal ligament: cervical ossification of the posterior longitudinal ligament. J Spine Part 1: Clinical results and limitations of laminoplasty. Spinal Disord 12:271–273, 1999 32: 647–653, 2007 33. Taketomi E, Sakou T, Matsunaga S, Yamaguchi M: Family 15. Iwasaki M, Okuda S, Miyauchi A, Sakaura H, Mukai Y, Yo- study of a twin with ossification of the posterior longitudinal nenobu K, et al: Surgical strategy for cervical myelopathy due ligament in the cervical spine. Spine 17 (3 Suppl):S55–S56, to ossification of the posterior longitudinal ligament: Part 2: 1992 Advantages of anterior decompression and fusion over lami- 34. Wang LF, Zhang YZ, Shen Y, Su YL, Xu JX, Ding WY, et al: noplasty. Spine 32:654–660, 2007 Using the T2-weighted magnetic resonance imaging signal in- 16. Jeanneret B, Magerl F, Ward EH, Ward JC: Posterior stabi- tensity ratio and clinical manifestations to assess the prognosis lization of the cervical spine with hook plates. Spine 16 (3 of patients with cervical ossification of the posterior longitudi- Suppl):S56–S63, 1991 nal ligament. Clinical article. J Neurosurg Spine 13:319–323, 17. Kawaguchi Y, Kanamori M, Ishihara H, Nakamura H, Sugi- 2010 mori K, Tsuji H, et al: Progression of ossification of the poste- 35. Yamaura I, Kurosa Y, Matuoka T, Shindo S: Anterior float- rior longitudinal ligament following en bloc cervical lamino- ing method for cervical myelopathy caused by ossification of plasty. J Bone Joint Surg Am 83-A:1798–1802, 2001 the posterior longitudinal ligament. Clin Orthop Relat Res 18. Kawano H, Handa Y, Ishii H, Sato K, Oku T, Kubota T: Surgi- 359:27–34, 1999 cal treatment for ossification of the posterior longitudinal ligament of the cervical spine. J Spinal Disord 8:145–150, 1995 19. Kim YJ, Lenke LG, Bridwell KH, Cho YS, Riew KD: Free Manuscript submitted November 16, 2010. hand pedicle screw placement in the thoracic spine: is it safe? Accepted December 20, 2010. Spine 29:333–342, 2004 Address correspondence to: Patrick A. Sugrue, M.D., Department 20. Kobashi G, Washio M, Okamoto K, Sasaki S, Yokoyama T, Mi- of Neurological Surgery, Northwestern University Feinberg School yake Y, et al: High body mass index after age 20 and diabetes of Medicine, 676 North St. Clair Street, Suite 2210, Chicago, Illinois mellitus are independent risk factors for ossification of the pos- 60611. email: [email protected].

Neurosurg Focus / Volume 30 / March 2011 7 Unauthenticated | Downloaded 09/26/21 11:47 PM UTC