Relationship between Enlargement of the Cross-Sectional Area of the Dural Sac and Neurological Improvements after Cervical Laminoplasty: Differences between Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament

Characteristics of the cervical spine and cervical cord injuries in older adults with cervical ossification of the posterior longitudinal ligament

Although the incidence of cervical spinal cord injury (CSCI) with ossification of the posterior longitudinal ligament (OPLL) has increased in older adults, its etiology and neurological outcomes remain unknown. We identified OPLL characteristics and determined whether they influence neurological severity and improvement of CSCI in older patients. This multicenter retrospective cohort study identified 1512 patients aged ≥ 65 years diagnosed with CSCI on admission during 2010-2020. We analyzed CSCI etiology in OPLL patients. We performed propensity score-adjusted analyses to compare neurological outcomes between patients with and without OPLL. Cases were matched based on variables influencing neurological prognosis. The primary neurological outcome was rated according to the American Spine Injury Association (ASIA) impairment scale (AIS) and ASIA motor score (AMS). In 332 OPLL patients, the male-to-female ratio was approximately 4:1. Half of all patients displayed low-energy trauma-induced injury and one-third had CSCI without a bony injury. Propensity score matching created 279 pairs. There was no significant difference in the AIS grade and AMS between patients with and without OPLL during hospitalization, 6 months, and 12 months following injury. OPLL patients tended to exhibit worse neurological findings during injury; nevertheless, OPLL was not associated with poor neurological improvement in older CSCI patients.

Is there any correlation between the recovery rate of JOA and the increasing of cervical spinal cord area after single-door cervical laminoplasty?

OBJECTIVES

The aim of the study is to investigate the clinical and radiologic factors represented by the increasing of spinal cord area associated with the prognosis of the patients at long-term follow-up by multivariate analysis after single-door cervical laminoplasty (SDCL).

METHODS

A total of 115 patients who underwent cervical laminoplasty with miniplate fixation were included from November 2008 to June 2018. The average postoperative follow-up period was 17.3 months (range, 12-105 months). The prognosis of the patients following cervical laminoplasty was evaluated by the recovery rate of Japanese Orthopedic Association (JOA) at the final follow-up. The recovery rate of JOA ≤ 50% were classified as poor prognosis group (PP group) whose prognosis is relatively poor, and those> 50% were classified as good prognosis group (GP group) whose have a better prognosis. The clinical factors including gender, age, duration of symptoms, diagnosis type, blood loss, operative time, pre- and post-JOA score, etc. were recorded. The radiologic factors including sagittal canal diameter (SCD), the cervical curvature index (CCI), the range of motion (ROM), the spinal canal area and the increasing of cervical spinal cord area, etc. were collected before and after operation and measured by X-ray plain and computed tomography (CT) scan images. The univariate analysis and multivariate logistic regression analysis were performed.

RESULTS

There were 62 patients in PP group and 53 patients in GP group. The multivariate analysis showed that the preoperative (OR=6.875, P = 0.001) and postoperative JOA scores (OR=24.000, P = 0.001), preoperative spinal canal area (OR=2.464, P = 0.023) and the increasing of cervical spinal cord area (OR=5.438, P = 0.001) maybe related factors to the recovery rate of JOA at the final follow-up.

CONCLUSIONS

The preoperative spinal canal area, the increasing of cervical spinal cord area, preoperative and postoperative JOA scores play important roles in long-term prognosis after SDCL.

Comparison of Surgical Outcomes After Open- and Double-Door Laminoplasties for Patients with Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Multicenter Study

STUDY DESIGN

A prospective multicenter study.

OBJECTIVE

To evaluate and compare the surgical outcomes after open-door (OD) and double-door (DD) laminoplasties in subjects with cervical ossification of the posterior longitudinal ligament (OPLL).

SUMMARY OF BACKGROUND DATA

Although previous studies compared clinical results after OD and DD laminoplasties, they were performed at a single institution with a relatively small sample size targeting mixed pathologies, including cervical spondylotic myelopathy.

METHODS

This study was performed by the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. A total of 478 patients with myelopathy caused by cervical OPLL from 28 institutions were prospectively registered from 2014 to 2017 and followed up for 2 years. Of these, 41 and 164 patients received OD and DD laminoplasties, respectively. Demographic information, medical history, and imaging findings were collected. Clinical outcomes were assessed using the cervical Japanese Orthopaedic Association, Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire, and visual analog scale scores.

RESULTS

Age, sex, symptom duration, and comorbidities were not significantly different between the groups. Segmental ossification was the most frequent in both the groups. No significant differences in K-line type, canal occupying ratio, C2 to C7 angles, and range of motion were found. Both the procedures reduced the cervical range of motion postoperatively. A comparable frequency of perioperative complications was observed between the groups. The cervical Japanese Orthopaedic Association scores showed a similar improvement at 2 years postopera- tively. The reduction in visual analog scale score for neck pain was favorable in the OD group (P = 0.02), while other pain assessments did not show any significant differences between the groups. The functional outcomes assessed using the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire presented equivalent effective rates.

CONCLUSION

The results demonstrated almost comparable surgical outcomes between OD and DD laminoplasties. Lamino- plasty is a valuable technique as a therapeutic option for cervical OPLL.Level of Evidence: 2.

Critical points and effectiveness of prophylactic C4/5 foraminotomy to prevent C5 palsy after posterior cervical spine surgery

OBJECTIVE

The aim of this study was to clarify the cut-off values of the spinal canal parameters as risk factors for C5 palsy after posterior cervical spine surgery with and without foraminotomy.

METHODS

One hundred three consecutive patients (67 males, 36 females; mean age = 66 years, age range = 27-87 years) with cervical myelopathy who underwent posterior cervical spine surgery at our institution were retrospectively reviewed and included in the study. The first consecutive 69 patients who underwent posterior cervical spine surgery with prophylactic bilateral C4/5 foraminotomy were designated as the F (+) group. The subsequent 34 consecutive patients who underwent posterior cervical spine surgery without prophylactic bilateral C4/5 foraminotomy were designated as the F (-) group. All patients were then divided into four subgroups. In the F (+) group, patients with C5 palsy were designated as the F (+) P (+) subgroup (n = 13), while those without C5 palsy were designated as the F (+) P (-) subgroup (n = 56). In the F (-) group, patients with C5 palsy were designated as the F (-) P (+) subgroup (n = 5), while those without C5 palsy were designated as the F (-)P(-) subgroup (n = 29). Receiver operating characteristic curves were used to investigate the cut-off values of the spinal canal parameters for the development of postoperative C5 palsy. The assessed spinal parameters were the gutter positions (GP), laminar inclination angles (LIA), and postoperative cross-sectional areas (CSA) of the dural sac. The risk ratios (RR) of the spinal canal parameters as risk factors for C5 palsy were evaluated.

RESULTS

The incidence of C5 palsy was similar between the F (+) group (18.8%) and the F (-) group (14.7%). The cut-off values for each spinal canal parameter in the F (+) group (GP: 0.82-0.84, LIA: 58.9-62.4°, and CSA: 189.5-200 mm2 ) were similar to those in the F (-) group (0.81-0.89, 61.7-62.5°, and 197.5-199.5 mm2, respectively). In the RR results for C5 palsy, the LIA was highest in both groups. The F (+) P (-) subgroup had significantly larger mean CSA at C4/5 and C5/6 (202.3 mm2 and 200.9 mm2, respectively) than the F (-)P(-) subgroup (177.3 mm2 and 178.9 mm2, respectively) (P = 0.0181 and P = 0.0277, respectively). Prophylactic C4/5 foraminotomy did not specifically prevent postoperative C5 palsy due to foraminal stenosis at C4/5.

CONCLUSION

C4/5 foraminotomy should not be recommended for avoidance of C5 palsy. Although the bony spinal parameters were similar between the F (+) and F (-) groups, the CSA in the F (+) group was significantly than that in the F (-) group in the patients without C5 palsy.

Open-door laminoplasty with stand-alone autologous bone spacers: evaluation of enlarged laminar arch with CT-multiplanar reconstruction

OBJECTIVE

The authors aimed to determine the efficacy of open-door laminoplasty with stand-alone autologous bone spacer for preserving enlarged lamina in patients with cervical myelopathy.

METHODS

Patients who underwent open-door laminoplasty for cervical myelopathy with stand-alone autologous bone spacer and underwent CT 1 week and 1 year after surgery were included in this study. There were 20 men and 13 women, with an average (range) age of 65.0 (37-86) years. Seventeen patients were younger than 70 years, and 16 patients were older than 70 years. Autogenous bone spacers made from spinous processes were used in all patients. Slits were made on both sides of the spacers. The lamina was raised with a curette, and a spacer was inserted without any sutures. Before surgery and 1 week and 1 year after surgery, the anteroposterior diameter (APD) of the spinal canal was measured using midsagittal-plane CT-multiplanar reconstruction. The bone union rate of the hinge side and autogenous bone spacer of each lamina was determined using CT images obtained 1 year after surgery. Results 1 year after surgery were evaluated using Japanese Orthopaedic Association (JOA) score.

RESULTS

The mean ± SD APD increase rate was 56.3% ± 21.3% 1 week after surgery and 51.7% ± 20.6% 1 year later. The average APD decrease rate was 2.9% ± 3.8%. The bone union rate on the hinge side was 100%, and that of autologous bone spacer was 93.8% 1 year after surgery. The mean APD decrease rate was 3.3% in patients younger than 70 years and 2.3% in those older than 70 years. There was no significant difference between the two groups (p > 0.05, nonpaired t-test). The JOA score averaged 10.1 before surgery and 13.3 a year after surgery (total score 17). The average improvement rate was 46.3% ± 26.4%.

CONCLUSIONS

The authors devised and implemented a technique for inserting an autologous bone spacer between the opened lamina and lateral mass without sutures. The enlarged spinal canal was maintained 1 year after surgery. This simple method does not require any instrumentation or additional cost to stabilize the opened lamina.

Modified K-line for Making Decisions Regarding the Surgical Approach in Patients with K-line (-) OPLL

Objective

To investigate whether the modified K‐line can be used to predict the clinical outcome and to determine the surgical approach for K‐line (−) patients with cervical ossification of the posterior longitudinal ligament (OPLL).

Methods

A new modified K‐line was defined as the line connecting the midpoints of the spinal cord at C₄ and C₆ on the lateral cervical radiographs. A total of four consecutive patients (three men and one woman) with cervical myelopathy due to OPLL were included in this research. The patients were diagnosed with OPLL with K‐line (−) while they were also classified as modified K‐line (+). Preoperative modified K‐line was used to predict the surgical outcome in K‐line (−) patients with OPLL according to the original K‐line. And a modified laminoplasty with C₃ laminectomy and C_4‐6 bilateral open‐door laminoplasty was adopted to perform on all the patients. The Japanese Orthopaedic Association scores before surgery and at 1‐year follow‐up after surgery were evaluated and the recovery rate was calculated. The visual analogue scale (VAS) scores were also evaluated before surgery and after surgery. Furthermore, cervical plain radiographs in neutral position before surgery and after surgery were obtained to measure C₂–C₇ angles for assessing the cervical sagittal alignment.

Results

The results showed that good neurological improvement could be achieved in all K‐line (−) patients who underwent C₃ laminectomy with C₄–C₆ bilateral open‐door laminoplasty. The Postoperative JOA scores improved from 13.5 to 16.5, from 11 to 16.5, from 13 to 16, and from 12.5 to 13, respectively. The mean recovery rate was 65.4% in the K‐line (−) patients. And the VAS scores dropped from 3 to 1, 5 to 2, 5 to 3, and 4 to 2, respectively. The JOA and VAS scores showed satisfaction in all patients at the 1‐year follow‐up. Relatively satisfactory and stable cervical sagittal alignment was observed on postoperative lateral radiography in all patients at the 3‐month follow‐up period. There were no postoperative complications associated with this technique found in all the patients.

Conclusions

Modified K‐line may predict the clinical outcome of this modified laminoplasty and offer guidance regarding the choice of surgical method for K‐line (−) patients with OPLL. Additionally, C₃ laminectomy with C₄–C₆ bilateral open‐door laminoplasty should be recommended for the use in patients with K‐line (−) OPLL, who were also classified as modified K‐line (+). However, further studies with more cases will be required to reveal its generalizability and availability.

Inadequate spinal cord expansion in intraoperative ultrasound after decompression may predict neurological recovery of degenerative cervical myelopathy

OBJECTIVE

To compare the neurological recovery between patients with adequate and inadequate immediate spinal cord expansion after sufficient decompression in degenerative cervical myelopathy (DCM).

METHODS

Twenty-seven patients subjected to French-door laminoplasty underwent the guidance of intraoperative ultrasound (IOUS) and were prospectively included. The modified Japanese Orthopedic Association (mJOA) score was evaluated before surgery and at 12 months postoperatively. The maximum spinal cord compression (MSCC) after sufficient decompression was calculated on the IOUS image; patients were divided into adequate (MSCC ≥ 0.95) and inadequate (MSCC < 0.95) expansion groups according to the MSCC. The mJOA score, spinal cord hyperechogenicity, age at surgery, symptom duration, occupational rate of the spinal canal, and the minimum anteroposterior diameter of the spinal cord between the two groups were compared.

RESULTS

Initially, 2 cases showed residual compression on IOUS; after further decompression, all patients acquired sufficient decompression. All patients achieved improvements in mJOA scores with an average recovery rate of 68.6 ± 20.3%. The recovery rate of the mJOA score of the inadequate expansion group was significantly inferior to that of the adequate expansion group (59.2 ± 21.7% versus 76.2 ± 16.2%, p = 0.028). The spinal cord hyperechogenicity was more common in the inadequate expansion group, while the spinal cord anteroposterior diameter of the inadequate expansion group was significantly smaller than that of the adequate expansion group.

CONCLUSIONS

The application of IOUS in French-door laminoplasty could help to confirm sufficient decompression for the treatment of DCM. Inadequate spinal cord expansion after sufficient decompression had the high possibility of predicting less satisfactory neurological recovery of DCM.

KEY POINTS

• The intraoperative ultrasound revealed that not all degenerative cervical myelopathy patients acquired adequate spinal cord expansion after sufficient decompression. • Patients who failed to acquire adequate spinal cord expansion commonly combined with spinal cord hyperechogenicity and trended to achieve less satisfactory neurological recovery after surgical decompression. • Inadequate spinal cord expansion after sufficient decompression had the high possibility of predicting less satisfactory neurological recovery of patients with degenerative cervical myelopathy.

Accuracy of the Gutter Position in Cervical Double-door Laminoplasty Using Intraoperative Computed Tomography Navigation and the Factors Associated With C5 Palsy

STUDY DESIGN

This was a prospective study.

OBJECTIVE

This study aimed to investigate the accuracy of the gutter position after cervical double-door laminoplasty (LP) using intraoperative computed tomography (CT) navigation and the factors associated with C5 palsy.

SUMMARY OF BACKGROUND DATA

There were some reports in which the gutter position and the width of decompression in cervical LP were associated with C5 palsy; however, there were few reports about the accuracy of the gutter position.

MATERIALS AND METHODS

Thirty-three patients treated with cervical LP were enrolled. We marked our targeted gutter position on the lamina with a high-speed drill using intraoperative CT navigation and performed the LP procedure. The accuracy of the gutter position was evaluated with a postoperative CT scan. We measured the angle of the opened lamina (AOL), the proportion of the distance between the gutters and the distance of transverse diameter of spinal canal (PGSC) with a postoperative CT scan and spinal cord posterior shifting (SCPS) with preoperative and postoperative magnetic resonance imaging scans. We investigated the incidence of C5 palsy and analyzed AOL, PGSC, and SCPS between the C5 palsy (+) and (-) groups.

RESULTS

The accuracy of all gutter positions was 78.4% (182/232). The accuracy of the gutter position at the right C4 and right C7 was lower than that at the other levels. The AOL in all cases was ~60 degrees. The PGSC was 90.1%-97.2%. The SCPS at C5 was the largest with 2.2 mm. C5 palsy occurred in 3 of 33 patients (9.1%). There were no significant differences in the AOL, PGSC, or SCPS between the 2 groups.

CONCLUSIONS

The accuracy of the gutter position using intraoperative CT navigation was good. The incidence of C5 palsy was higher in this study than in the previous reports.

Can prophylactic C4/5 foraminotomy prevent C5 palsy after cervical laminoplasty with and without posterior instrumented fusion with maximal expansion?

OBJECTIVE

To prospectively examine whether laminoplasty with maximal expansion induces C5 palsy, even with prophylactic bilateral C4/5 foraminotomy.

METHODS

Thirty-five consecutive patients with cervical myelopathy underwent laminoplasty (n = 19: LP group) or posterior decompression and fusion (n = 16: PDF group) with maximal expansion. Prophylactic bilateral C4/5 foraminotomy was performed alternately in consecutive five patients undergoing each type of surgery. In each type of surgery, the first and third consecutive five patients did not undergo foraminotomy (NF subgroup: 20 patients), while the second and fourth consecutive five patients underwent foraminotomy (F subgroup: 15 patients). The widths between the gutters was equivalent to the diameter of the spinal canal, and an inclination angle of the lamina of approximately 90° was created during laminoplasty. The incidence and severity of postoperative C5 palsy were investigated. Patients with a manual muscle testing score for the deltoid muscle and/or biceps brachii muscle of ≤ 2 were diagnosed with severe palsy.

RESULTS

The respective incidences of C5 palsy in the F and NF subgroups were 33% and 20% in the LP group and 50% and 20% in the PDF group. Severe palsy occurred in 67% and 0% of patients who had developed palsy in F and NF subgroups, respectively, in the LP group, and in 100% of patients in the PDF group. Furthermore, 40% of the patients with severe palsy took more than 6 months to recover.

CONCLUSIONS

Laminoplasty with maximal expansion induced C5 palsy in both the LP and PDF groups, even with the addition of prophylactic bilateral C4/5 foraminotomy.

Improvement in the results of the simple-foot-tapping test and cross-sectional area of the dural sac in patients with C5 palsy after posterior cervical spine surgery

INTRODUCTION

The smaller cross-sectional areas of the dural sacs in patients without C5 palsy after posterior cervical spine surgery may lead to less neurological improvement.

OBJECTIVES

The aim of this retrospective study was to clarify the differences in the cross-sectional area of the dural sac in the cervical spine and neurological improvement in patients with and without C5 palsy after posterior cervical spinal surgery.

METHODS

We retrospectively evaluated the postoperative cross-sectional areas of the dural sacs and neurological outcomes in patients with and without C5 palsy after posterior cervical spine surgery. We compared the postoperative cross-sectional areas of the dural sac at C4/5 and C5/6 on magnetic resonance images between the C5 palsy group (n = 19) and the no-C5 palsy group (n = 84) after posterior cervical spinal surgery 1 year postoperatively. Performance tests, namely, the 10-s grip-and-release test and the 10-s single-foot-tapping (FT) test, were compared between the two groups.

RESULTS

Postoperative cross-sectional areas of the dural sac at C4/5 and C5/6 (233.3 mm² and 226.6 mm², respectively) in the C5 palsy group were significantly larger (P = 0.0036 and P = 0.0039, respectively) than those (195.0 mm² and 193.8 mm², respectively) in the no-C5 palsy group. Postoperative gain in the grip-and-release test was similar between the two groups. Postoperative gain in the FT test (4.9 times) in the C5 palsy group was significantly larger (P = 0.0060) than that (1.8 times) in the no-C5 palsy group.

CONCLUSIONS

In the C5 palsy group 1 year after posterior cervical spine surgery, the cross-sectional areas of the dural sac were larger, and the 10-s single FT test improved noticeably.

A New Grading of Epidural Hematoma or Scar Formation after Posterior Cervical Spine Surgery: Evaluation of Perioperative Related Factors, Distributions, and Clinical Outcomes after Surgery

Introduction

The purpose of this study was to evaluate surgical outcomes using a new grading of postoperative epidural hematoma (EH) or epidural scar formation after posterior cervical spine surgery.

Methods

Postoperative EH or epidural scar formation after cervical laminoplasty (LP) or posterior decompression and fusion (PDF) were graded into Grades 1-5 by magnetic resonance imaging at 24 hours, 2 weeks, 6 months, and one year after surgery. The patients were divided into the Mild group (Grades 1-3) and the Severe group (Grades 4, 5). Perioperative factors were compared between the two groups at 24 hours after surgery. Distribution of EH or scar formation was investigated according to two surgeries. The recovery rate of Japanese Orthopedic Association (JOA) scores and the improvements of neck disability index (NDI) were compared between the two groups at one year postoperatively.

Results

Of the postoperative factors, posterior shift of the cervical spinal cord at C4 and C7 significantly differed between the two groups. Patients in the Severe group at 24 hours after surgery (17%) increased to 41% at 2 weeks and subsequently decreased to 16% at 6 months after LP. After PDF, 3% in the Severe group at 24 hours after surgery increased to 15% at 2 weeks and then decreased to 3% at 6 months postoperatively. Only one (3%) patient remained in the Severe group at 1 year after PDF. The recovery rate of JOA score (47.5%) of the patients in the Mild group showed trend larger than that of the Severe group (34.7%) after LP. Preoperative NDI (15.6 points) significantly improved postoperatively to 12.1 points in only the Mild group after LP.

Conclusions

The patterns of distribution of EH or scar formation did not differ between the two surgical methods. The severity of postoperative scar formation related to surgical outcomes after LP.