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 Table of Contents  
ORIGINAL ARTICLES
Year : 2021  |  Volume : 4  |  Issue : 2  |  Page : 181-187

Efficacy of posterior cervical laminectomy for multilevel cervical ossification of posterior longitudinal ligament


Mumbai Institute of Spine Surgery, Bombay Hospital and Medical Research Centre, Marine Lines, Mumbai, Maharashtra, India

Date of Submission23-Oct-2020
Date of Decision09-Jan-2021
Date of Acceptance09-Feb-2021
Date of Web Publication16-Jul-2021

Correspondence Address:
Sanjeev Asati
Mumbai Institute of Spine Surgery, Room No. 128, First Floor, M.R.C. Wing, Bombay Hospital and Medical Research Centre, Marine Lines, Mumbai 400020, Maharashtra.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ISJ.ISJ_84_20

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  Abstract 

Study Design: This study design includes retrospective study of prospectively collected data. Introduction: The purpose is to determine the efficacy of posterior cervical laminectomy for multilevel cervical ossified posterior longitudinal ligament (OPLL). Laminectomy has been a preferred surgical treatment for multilevel cervical OPLL since a long time. Because of the risk associated with progressive kyphosis, the trend is shifted from laminectomy alone to laminoplasty and laminectomy with fusion. The data regarding the efficacy of laminectomy alone in terms of clinical and radiological parameters in multilevel cervical OPLL are scanty. Materials and Methods: We reviewed 82 patients with multilevel cervical OPLL who underwent posterior cervical laminectomy from January 2008 to December 2014. Patients with age ≥45 years, C2–C7 Cobb’s angle ≥ 10º, compression at ≥3 levels, and a minimum of 5 years of follow-up were included in the study. Demographics, pre and postoperative clinical parameters (visual analog scale (VAS), Nurick’s grading, and modified Japanese orthopedic association (mJOA) score), radiological parameters (C2–C7 Cobb’s angle, C2–C7 sagittal vertical axis (SVA)), perioperative parameters, complications, and recovery rate were evaluated. Results: The mean age of the patients was 56.4 (46–72) with M: F of 52:30. The mean blood loss and mean operative time were 93.9 mL and 96.6 min, respectively. There was significant improvement (P < 0.05) in VAS (3.6 ± 1.4 to 1.8 ± 0.8), Nurick’s grading (3.2 ± 0.9 to 1.9 ± 0.6), and mJOA score (8.4 ± 1.4 to 13.8 ± 1.9). C2–C7 Cobb’s angle increased from ‒14.4 ± 1.7º preoperatively to ‒8.2 ± 1.5º postoperatively and C2–C7 SVA from 18.4 ± 12.5 to 29.8 ± 15.8. Intraoperatively four patients had a dural tear. Three patients showed neurological deterioration postoperatively and three had unilateral C5 palsy which improved within a period of 6 months. 18.3% had an excellent outcome, 40.3% had good, 34.1% had fair, and 7.3% of the patients had a poor outcome. Conclusion: Multilevel cervical laminectomy is an effective surgical procedure in properly selected patients with multilevel OPLL. The outcomes are satisfactory in terms of radiological and clinical parameters. The risk of postlaminectomy kyphosis is not too high, and we found no correlation of kyphosis with clinical affection.

Keywords: C5 palsy, cervical laminectomy, CSF leak, multilevel OPLL, neurological deterioration


How to cite this article:
Asati S, Kundnani VG, Sagane SS, Jain S, Raut S. Efficacy of posterior cervical laminectomy for multilevel cervical ossification of posterior longitudinal ligament. Indian Spine J 2021;4:181-7

How to cite this URL:
Asati S, Kundnani VG, Sagane SS, Jain S, Raut S. Efficacy of posterior cervical laminectomy for multilevel cervical ossification of posterior longitudinal ligament. Indian Spine J [serial online] 2021 [cited 2021 Dec 4];4:181-7. Available from: https://www.isjonline.com/text.asp?2021/4/2/181/321584




  Introduction Top


Ossification of the posterior longitudinal ligament (OPLL) is a pathological ossification of the PLL which narrows the spinal canal and is an important cause of cervical myelopathy.[1] It leads to progressive deterioration of neurological function which demands surgical treatment, but there remains a controversy regarding the ideal surgical procedure.[2] Various surgical options available are anterior corpectomy and fusion, laminectomy alone, laminoplasty and laminectomy with fusion (LF).[3],[4],[5],[6],[7],[8] For multilevel compression due to failure of fusion in anterior procedures, posterior decompression, which causes indirect decompression of the cord resulting in shift of the spinal cord, is preferred. Complications of standalone laminectomy including spinal instability, postoperative spinal deformity, postlaminectomy membrane causing compression, axial neck pain, and postoperative progression of OPLL led surgeons to perform laminoplasty and decompression with fusion.[9],[10] Kyphosis leads to traction of the spinal cord and ischemia due to the stretching and flattening of small vessels which can cause a delayed neurological affection. Studies have suggested that laminectomy completely relieved stenosis, whereas laminoplasty only partially relieved the degree of stenosis.[10],[11] Another study suggested that the long-term results of laminectomy are similar to those of laminoplasty.[12] Although some studies have shown the outcomes of laminectomy alone in cervical OPLL, data are still scanty.[13],[14],[15]

Here we present our experience with laminectomy alone in patients with multilevel OPLL with respect to functional recovery, complications, and radiological outcomes.


  Materials and Methods Top


After obtaining permission from the Ethics Committee and hospital management, this retrospective analysis was done on 82 of the 90 patients (eight lost to follow-up) with multilevel OPLL who underwent posterior cervical laminectomy in a single hospital by a single surgeon from January 2008 to December 2014. Preoperatively all the patients had signs and symptoms of long tract involvement, such as hand clumsiness, gait disturbance, and hyperreflexia in lower limbs. Patients with age ≥45 years, C2–C7 Cobb’s angle ≥ 10º, compression at ≥3 levels, and a minimum of 5 years of follow-up were included in the study. Patients with only axial neck pain without myelopathy, instability on dynamic X-ray, fracture/infection/metabolic disorders, revision surgery, and having developmentally narrow canal were excluded from the study. Demographic data (age, sex, BMI, duration of illness to presentation, and comorbidities) were noted.

Clinical assessment

Clinical outcomes were assessed by pre- and postoperative evaluation of neck pain score (VAS), Nurick’s grading, and modified Japanese orthopedic association (mJOA) score [Figure 1] given by Benzel et al. (score 0–18).[16] The recovery rate was calculated as follows: recovery rate (%) = [postoperative JOA score – preoperative JOA score]/[18–preoperative JOA score] × 100. A recovery rate of >75% was considered an excellent outcome, 50–75% as good outcome, 25–49% as fair outcome, and <25% was considered a poor outcome. Factors associated with poor surgical outcomes were assessed.
Figure 1: Modified JOA score

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Radiological assessment

In all the patients, preoperative X-rays (dynamic films), CT scan, and MRI of cervical spine were done. OPLL was classified according to the classification of the spinal ligaments of the Japanese Ministry of Public Health and Welfare into continuous, segmental, mixed, and localized varieties[17] [Figure 2].
Figure 2: OPLL types: (A) segmental, (B) continuous, and (C) mixed

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Levels of affection and maximum compression were documented, and sagittal cervical Cobb’s angle (C2–C7 Cobb’s) and C2–C7 sagittal vertical axis (SVA) measurement were done preoperatively and during subsequent follow-ups [Figure 3].
Figure 3: (A) C2–C7 Cobb’s angle and (B) C2–C7 SVA

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Complications were divided into intraoperative (dural tear), early postoperative (within 15 days) (hematoma, infection, CSF leak, C5 palsy, neurological deterioration), and late postoperative (after 15 days) (delayed neurological deterioration, axial neck pain, reoperation, kyphosis) and were assessed.

Surgical procedure

Under general anesthesia, the patient was positioned prone on padded bolsters. The neck was placed in neutral or mild flexion. The arms were strapped by the side. A standard midline posterior exposure from C3 to C6 was carried out up to the lamina–facet junction, taking care to preserve the attachments to C2 and C7. The dissection was restricted just lateral to the lamina–facet junction, and the soft tissue attachments over the facet joints were preserved. The furrow at the junction of the lamina and facet joints was marked at all levels requiring laminectomy. The gutters were created on both sides using a high-speed cutting burr till the inner cortex was reached; 1-mm Kerrison rongeur was used to remove the flavum up to the lateral gutters created. The rongeur was used to complete the furrows on either side all the way up to the C2–C3 interlaminar space. The laminectomy was completed by lifting the laminae en bloc from the caudal end, and gentle dissection was performed for any adhesion between the ligamentum flavum and dura. Undercutting of C2 and C7 laminae was done in some cases, and C4-C5 foraminotomy was done in all the cases as a precautionary measure for C5 palsy.

Postoperatively, patients were encouraged to sit up in bed 24 h after the surgery. Patients were mobilized out of bed on the second postoperative day using a soft cervical collar which was discontinued after suture removal.

Patients were sequentially followed up at 4 weeks, 3 months, 6 months, 12 months, and then annually. At each follow-up, clinical and radiological evaluation was done.

Statistical analysis was carried out using a paired Student’s t-test. Differences were considered statistically significant at P < 0.05. Statistical analysis was done using SPSS software 20.0 (SPSS Inc., Chicago, IL, USA).


  Results Top


The study started with 90 patients, of whom eight patients were lost to follow-up and 82 patients were included in the study. The mean age of the patients was 56.4 (46–72) with M: F of 52:30. In total, 29 patients (35.3%) had continuous, 22 (26.8%) had segmental, and 31 (37.8%) had mixed variety of OPLL. The OPLL was distributed at 314 levels in 82 patients with an average of 3.8 (3–5). Radiologically, myelomalacia was seen in 39 (47.5%) patients and double-layer sign (dural ossification) was present in 22 (26.8%) patients. Laminectomy was performed at a total of 352 levels. The mean duration of symptoms at the time of presentation was 5.1 months, and the mean follow-up in years was 7.4 (5–11). Thirty-eight patients had two or more comorbidities, 33 had less than two, and 11 had no comorbidity [Table 1].
Table 1: Demographics

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The mean blood loss was 93.9 mL (70–180) and the mean operative time was 96.6 min (82–140) [Table 2].
Table 2: Perioperative parameters

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Clinical outcomes

VAS demonstrated significant improvement (P < 0.05) from 3.6 ± 1.4 preoperatively to 1.8 ± 0.8 postoperatively. There was significant difference (P < 0.05) in Nurick’s grading from 3.2 ± 0.9 preoperatively to 1.9 ± 0.6 postoperatively. The mJOA score improved from 8.4 ± 1.4 preoperatively to 13.8 ± 1.9 postoperatively (P < 0.05) [Table 3]. The mean recovery rate at final follow-up was 57.7%. Out of the 82 patients, 15 (18.2%) had an excellent outcome, 33 (40.2%) had good, 28 (34.1%) had fair, and 6 (7.3%) patients had a poor outcome [Table 3].
Table 3: Clinical and radiological outcomes

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Radiological outcomes

All the patients with ≥10º C2–C7 Cobb’s angle were included in the study. C2–C7 Cobb’s angle increased from ‒14.4 ± 1.7º preoperatively to ‒8.2 ± 1.5º postoperatively. Out of the 82 patients, 52 (63.4%) maintained cervical lordosis, 18 (21.9%) changed to a straight spine, and 12 (14.6%) became kyphotic (kyphosis greater than +5°, straight from ‒5º to +5°, lordosis less than ‒5º). C2–C7 SVA changed from 18.4 ± 12.5 preoperatively to 29.8 ± 15.8 postoperatively at final follow-up [Table 3].

Complications

Intraoperatively, four (4.8%) patients had a dural tear, and no repair was done intraoperatively. There was no case of postoperative CSF leak. Three (3.6%) patients showed postoperative hematoma formation which resolved gradually without any surgical intervention. Superficial infection developed in four (4.8%) individuals, for which intravenous antibiotics were given till the healing and there was no case of deep infection or wound dehiscence. Three (3.6%) patients showed neurological deterioration just after the surgery, two of which showed decrease in their mJOA score by 5 points and one showed decrease in mJOA by 3 points. Over the time, mJOA improved to their preoperative level. Three (3.6%) patients had an isolated unilateral C5 palsy which was transient in nature and improved within 6 months period with regular physiotherapy. Over the time, 18 (21.9%) patients complained of axial neck pain without any radiculopathy or weakness, which was mild in nature and managed with NSAIDs and physiotherapy. There was no case of delayed neurological deterioration and no patient was re-operated for the same condition [Table 4].
Table 4: Complications

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Case example

Cervical CT scan [(4a) sagittal and (4c) axial] shows mixed type of OPLL from C2-C6 with significant canal compression (>50%) and myelomalacia [MRI sagittal (4b) and axial (4d)] changes in the spinal cord [Figure 4]. Postoperative MRI [(4e) sagittal and (4f) axial] after multilevel laminectomy shows well-decompressed canal.
Figure 4: Cervical CT scan [(A) sagittal and (C) axial] showing mixed type of OPLL from C2–C6 with significant canal compression (>50%) and myelomalacia [MRI sagittal (B) and axial (D)] changes in the spinal cord. Postoperative MRI [(E) sagittal and (F) axial] after multilevel laminectomy showing well-decompressed canal

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  Discussion Top


Cervical OPLL was first described in the Japanese population in which the incidence is 1.9–4.3% in patients with cervical spine disorders, whereas in other Asian countries, it is as high as 3.0%.[18],[19] These patients are particularly at an increased risk of acute spinal cord injury and rapid neurologic deterioration with trauma[20] Surgical treatment is usually required which includes anterior, posterior, or combined anterior and posterior approach.[13] The primary goal is to decompress the neural structures either by direct resection of the OPLL or by spinal canal expansion. Anterior decompression with direct removal is effective but complication rates are higher in multilevel cases.[21] Posterior decompression (laminectomy) with or without fusion is reliable and effective in treating multilevel OPLL.[22]

The incidence of kyphotic change after multilevel laminectomy is approximately 20%.[23] Different predisposing causes include young age, preoperative kyphosis, aggressiveness of posterior soft tissue resection, extent of facetectomy or capsule resection, and multiplicity of laminectomy level. Facet injury is the most significant cause of postoperative kyphosis.[24] To overcome the disadvantages associated with laminectomy procedure, laminoplasty came into light which preserves the posterior elements that protect the spinal cord against external forces and might decrease the incidence of neurological deterioration caused by falls by providing spinal stability.[14],[25] Despite a variety of laminoplasty techniques, its advantages over laminectomy remains unclear. A review of the literature revealed that the general result in the long-term follow-up of laminoplasty patients is similar to that in laminectomy patients.[12] Lee et al.[13] in their study suggested that there was no significant difference between cervical lordosis over time in patients operated by laminectomy alone, laminoplasty, and LF.

In our study, the C2-C7 Cobb’s angle increased from ‒14.4 ± 1.7º preoperatively to ‒8.2 ± 1.5º postoperatively. About 63.4% of the patients maintained cervical lordosis, in 21.9% curvature changed to a straight spine, and 14.6% became kyphotic. In Lee et al.’s study, the preoperative global angle changed from ‒11.3° ± 7.0° to ‒8.4° ± 8.1° and 70.6% maintained their original curvature or improved from straight spine to lordosis, in three patients lordosis changed to kyphosis, and in four patients lordosis changed to kyphosis.[15] Kato et al.[14] showed that 14 (47%) of the 30 patients demonstrated a change in cervical alignment; none of the patients suffered neurological deterioration and suggested that good results from laminectomy could be maintained over a long period. Lee et al.[13] showed change in cervical Cobb’s angle from 10.0° ± 11.6° to 5.1° ± 12.0° in the fusion group. In the present study, C2–C7 SVA changed from 18.4 ± 12.5 preoperatively to 29.8 ± 15.8 postoperatively at final follow-up, whereas in Lee et al.’s[13] study, the laminectomy group showed a change from 29.1 ± 13.3 to 35.0 ± 15.9, both of which are comparable. The fusion group showed a change from 29.5 ± 10.7 to 29.2 ± 10.9, which is non-significant. Facet resection of more than 50% is thought to cause significant kyphosis and instability.[24] Studies have also suggested that preservation of attachments of C2 and C7 leads to less axial neck pain and progression of kyphosis. The reasons for the maintenance of cervical lordosis in our study can be due to limiting the dissection and preservation of facet capsule during laminectomy, preservation of C2 and C7 attachments, and the selection of only those patients who have a C2–C7 Cobb’s angle of ≥ 10º.

The mean recovery rate in the present study at final follow-up was 57.7% which was more than that in the study done by Kato et al.[14] and comparable with Lee et al.’s[15] study in which the recovery rate was 56.3 ± 31.1%. We observed that history of trauma, high BMI, a low preoperative mJOA score, and late presentation were associated with delayed recovery, whereas higher preoperative JOA score and younger age at surgery were associated with early recovery.

Progression of OPLL was seen in 65.4% of the patients which is lesser than that suggested by Hori et al.[26] (71% at 10 years) and more than that suggested by Chiba et al.[27] where it was 56.5% of the patients after 2 years. Kato et al.[14] showed progression of OPLL in 70% of the cases, while one patient suffered neurological worsening because of the progression. We have not seen any such case of delayed deterioration in our study.

The overall complications associated with OPLL surgery vary from 5.2% to 57.6%. Complications depend on a variety of factors such as approach, surgeons’ experience, and comorbidities.[28] The AO Spine International Study[29] found that OPLL was a significant risk factor for perioperative complications in patients undergoing surgical treatment of degenerative cervical myelopathy. The risk of durotomy during laminectomy is 0.3–13% and can be up to 18% with revision surgery.[30] Singhatanadgige et al.[2] found that the incidence of C5 palsy was higher 9.6–25%, following laminoplasty with fusion compared with 0–8% in the laminoplasty group. Lee et al. observed 5.9% C5 palsy in their study.[15] In our study, the incidence of C5 palsy was 3.6% which recovered spontaneously within 6 months of period. Axial neck pain may be the most frequently reported complication of OPLL surgery, with reports of its incidence ranging anywhere from 16% to 48%. We observed 21.9% incidence of axial neck pain which was manageable with medications.

As per our results and understanding, we suggest cervical laminectomy for patients with cervical OPLL ≥3 levels, without instability and C2–C7 Cobb’s angle >10°. Complications associated with fixation like higher incidences of C5 palsy, pseudoarthrosis, and more surgical time in old and debilitated patients can be avoided. There are chances of postlaminectomy kyphosis which can be prevented by proper patient selection and OPLL progression, which we think is only radiological without any clinical effect. This is a single surgeon, single hospital study and to our knowledge is the only study done on this pathology in Indian subcontinent with a long-term follow-up.

There are several limitations in this study. First, the study is retrospective and represents the experience of a single surgeon in a single institute. Though it is retrospective in nature all the data were collected prospectively. Secondly, our inclusion criteria were narrow because of which it cannot be used in large numbers of patients. Thirdly, there is no comparative group in our study. To determine the actual efficacy, multicentric comparative studies are needed.


  Conclusion Top


Multilevel cervical laminectomy is an effective surgical procedure in properly selected patients with multilevel OPLL. The outcomes are satisfactory in terms of radiological and clinical parameters. The risk of postlaminectomy kyphosis is not too high, and we found no correlation of progression of kyphosis with clinical affection.

Financial support and sponsorship

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflicts of interest

The authors have no conflicts of interests to disclose.



 
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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