Impact of longitudinal distance of the cervical spine on the results of expansive open-door laminoplasty

Effectiveness of additional C2 decompression of the cervical spinal canal after cervical laminoplasty: a retrospective cohort study

PURPOSE

This study aimed to assess the effects of additional C2 decompression of the cervical spinal canal on the postoperative outcomes after cervical laminoplasty in patients with cervical stenosis caused by ossification of the posterior longitudinal ligament (OPLL).

MATERIALS AND METHODS

This retrospective cohort study included patients with cervical stenosis due to OPLL and treated between April 2014 and December 2015. The patients who underwent C2-7 (additional C2 decompression) and C3-7 posterior decompression were compared using the Japanese Orthopedic Association (JOA) scores, visual analog scale (VAS) scores, axial symptom scores, and intervals between the posterior margin of the vertebral body and the K-line.

RESULTS

There were 36 and 24 patients in the additional C2 decompression and control groups, respectively. The JOA scores were higher in the additional C2 decompression group than the controls at 1 and 3 years (p < 0.05). Upper extremity motor function after the operation and at 1 and 3 years and lower extremity motor function after operation were improved in the additional C2 decompression group (all p < 0.05 vs. controls). VAS scores were lower in the additional C2 decompression group than controls at 1 year (p < 0.05). Axial symptom scores in the additional C2 decompression group were decreased postoperatively but increased at 1 and 3 years (p < 0.05 vs. controls). Finally, the posterior shift of the K-line in the additional C2 decompression group was significant (from 0.98 to 1.68 cm, p < 0.05).

CONCLUSIONS

Additional C2 decompression might improve the effectiveness of cervical laminoplasty in patients with cervical stenosis caused by OPLL.

Novel Risk Factors for Cervical Facet Joint Degeneration in the Subaxial Cervical Spine: Correlation with Cervical Sagittal Alignment and Bone Mineral Density

OBJECTIVE

The impact of cervical sagittal alignment on cervical facet joint degeneration (CFD) and the risk factors for CFD in patients with degenerative cervical myelopathy (DCM) were investigated in the current study.

METHODS

A total of 250 surgical patients with DCM were recruited. The clinical data and radiographical characteristics, including CFD, cervical sagittal balance parameters, Hounsfield unit (HU) values, disc degeneration (DD), and modic change, were collected. The detailed correlation between these characteristics and CFD was analyzed. Characteristics, including CFD, were compared among the various cervical alignment types and different CFD groups. Finally, the risk factors for CFD were revealed via logistic regression.

RESULTS

CFD was prevalent in DCM patients. Age, cervical sagittal vertical axis (cSVA), range of motion, T1 slope, thoracic inlet angle, DD, HU value, and modic change correlated with CFD segmentally and globally (P < 0.05). The lordosis and sigmoid types had a significantly higher CFD prevalence (P < 0.05). Furthermore, the average CFD threshold for the severe CFD group was 1.625 (area under the curve, 0.958). Additionally, 167 patients with average CFD <1.625 and 83 patients with CFD of ≥1.625 were classified into the mild CFD group and severe CFD group, respectively. Finally, multivariate analysis was performed, and age, cSVA, HU value, modic change, and DD were determined to be independent risk factors for CFD.

CONCLUSIONS

The load distribution tends to shift to a more shear-like pattern in the sigmoid and kyphosis types and in those with a higher cSVA, thereby promoting CFD. Aging, cervical malalignment, low bone mineral density, DD, and modic change were revealed to result in high risks of CFD.

Dynamic Cervical Spinal Canal Stenosis: Identifying Imaging Risk Factors in Extended Positions

STUDY DESIGN

A retrospective study at a single academic institution.

PURPOSE

This study aimed to identify imaging risk factors for stenosis in extended neck positions undetectable in preoperative neutral magnetic resonance imaging (MRI) and improving decompression strategies for cervical spine disorders.

OVERVIEW OF LITERATURE

Cervical disorders are influenced by various dynamic factors, with spinal stenosis appearing during neck extension. Despite the diagnostic value of dynamic cervical MRI, standard practice often uses neutral-position MRI, potentially influencing surgical outcomes.

METHODS

This study analyzed 143 patients who underwent decompression surgery between 2012 and 2014, who had symptomatic cervical disorders and MRI evidence of spinal cord or nerve compression but had no history of cervical spine surgery. Patient demographics, disease type, Japanese Orthopedic Association score, and follow-up periods were recorded. Spinal surgeons conducted radiological evaluations to determine stenosis levels using computed tomography myelography or MRI in neutral and extended positions. Measurements such as dural tube and spinal cord diameters, cervical alignment, range of motion, and various angles and distances were also analyzed. The residual space available for the spinal cord (SAC) was also calculated.

RESULTS

During extension, new stenosis frequently appeared caudal to the stenosis site in a neutral position, particularly at C5/C6 and C6/C7. A low SAC was identified as a significant risk factor for the development of new stenosis in both the upper and lower adjacent disc levels. Each 1-mm decrease in SAC resulted in an 8.9- and 2.7-fold increased risk of new stenosis development in the upper and lower adjacent disc levels, respectively. A practical SAC cutoff of 1.0 mm was established as the threshold for new stenosis development.

CONCLUSIONS

The study identified SAC narrowing as the primary risk factor for new stenosis, with a clinically relevant cutoff of 1 mm. This study highlights the importance of local factors in stenosis development, advocating for further research to improve outcomes in patient with cervical spine disorders.

Clinical outcome of surgical management of mild cervical compressive myelopathy based on minimum clinically important difference

BACKGROUND CONTEXT

Cervical compressive myelopathy (CCM), caused by cervical spondylosis (cervical spondylotic myelopathy [CSM]) or ossification of the posterior longitudinal ligament (OPLL), is a common neurological disorder in the elderly. For moderate/severe CCM, surgical management has been the first-line therapeutic option. Recently, surgical management is also recommended for mild CCM, and a few studies have reported the surgical outcome for this clinical population. Nonetheless, the present knowledge is insufficient to determine the specific surgical outcome of mild CCM.

PURPOSE

To examine the surgical outcomes of mild CCM while considering the minimum clinically important difference (MCID).

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Patients who underwent subaxial cervical surgery for CCM caused by CSM and OPLL between 2013 and 2022 were enrolled.

OUTCOME MEASURES

The Japanese Orthopedic Association score (JOA score) was employed as the clinical outcomes. Based on previous reports, the JOA score threshold to determine mild myelopathic symptoms was set at ≥14.5 points, and the MCID of the JOA score for mild CCM was set at 1 point.

METHODS

The patients with a JOA score of ≥14.5 points at baseline were stratified into the mild CCM and were examined while considering the MCID. The mild CCM cohort was dichotomized into the improvement group, including the patients with an achieved MCID (JOA score ≥1 point) or with a JOA score of 17 points (full mark) at 1 year postoperatively, and the nonimprovement group, including the others. Demographics, symptomatology, radiographic findings, and surgical procedure were compared between the two groups and studied using the receiver operating characteristic (ROC) curve.

RESULTS

Of 335 patients with CCM, 43 were stratified into the mild CCM cohort (mean age, 58.5 years; 62.8% male). Among them, 25 (58.1 %) patients were assigned to the improvement group and 18 (41.9 %) were assigned to the nonimprovement group. The improvement group was significantly younger than the nonimprovement group; however, other variables did not significantly differ. ROC curve analysis showed that the optimal cutoff point of the patient's age to discriminate between the improvement and nonimprovement groups was 58 years with an area under the curve of 0.702 (p=.015).

CONCLUSIONS

In the present study, the majority of patients with mild CCM experienced improvement reaching the MCID of JOA score at 1 year postoperatively. The present study suggests that for younger patients with mild CCM, especially those aged below 58 years, subjective neurological recovery is more likely to be obtained. Meanwhile, the surgery takes on a more prophylactic significance to halt disease progression for older patients. The results of this study can help in the decision-making process for this clinical population.

Surgical Outcomes of Selective Laminectomy for Patients With Cervical Kyphosis: A Retrospective Study of 379 Cases

STUDY DESIGN

A retrospective study.

OBJECTIVES

This study aimed to investigate the impact of cervical kyphosis on patients with cervical spondylotic myelopathy (CSM) following selective laminectomy (SL) regarding posterior spinal cord shift (PSS), and a number of SLs.

METHODS

We evaluated 379 patients with CSM after SL. The patients with kyphosis (group K) were compared with those without kyphosis (group L). Moreover, groups K and L were divided into subgroups KS and KL (SLs ≤ 2) and LS and LL (SLs ≥ 3), respectively, and analyzed. Receiver operating characteristic (ROC) curve analysis was performed to determine the cut-off value of the C2-C7 angle for satisfactory surgical outcomes, which was defined as a Japanese Orthopaedic Association (JOA) recovery rate of ≥50% in group KS.

RESULTS

The average PSS (mm) in group K was smaller than that in group L (.8 vs 1.4; P < .01), but the JOA recovery rate was comparable between the 2 groups. Meanwhile, the mean PSS and JOA recovery rate (%) in group KS was lower than those in group KL, respectively (.3 vs 1.0; P < .01, 35.1 vs 52.3; P = .047). Moreover, the average PSS of group KS (.6) was smaller than those of other subgroups ( < .01). In addition, the ROC curve analysis showed that the C2-C7 angle of -14.5° could predict satisfactory surgical outcomes in group KS.

CONCLUSION

Selective laminectomy is not contraindicated for patients with kyphosis, but a larger number of SLs may be indicated for the patients with C2-C7 angles of ≤ -14.5°.

Usefulness of K-line in predicting prognosis of laminoplasty for cervical spondylotic myelopathy

BACKGROUND

K-line is widely recognized as a useful index for evaluating cervical alignment and the size of the cervical ossification at the posterior longitudinal ligament (OPLL). The purpose of this study was to investigate whether the K-line could be a useful clinical tool for predicting the prognosis of laminoplasty (LP) for cervical spondylotic myelopathy (CSM).

METHODS

Adult CSM patients scheduled for cervical LP were recruited for this study. C2-7 angle, local kyphosis angle, and K-line was evaluated by T2-weighted sagittal magnetic resonance imaging (MRI). Clinical findings were evaluated by the JOA score and the recovery rate. Clinical and radiological findings were evaluated preoperation and final follow-up. Patients were grouped into K-line ( +) and K-line (-). Patients with Kline (-) were further divided into two sub-groups: disc type (anterior cord compression due to disc protrusion with kyphosis) and osseous type (due to osseous structure such as osteophyte).

RESULTS

Sixty-eight patients were included in the analysis. The recovery rate of K-line (-) group (n = 11,19.4%) was significantly worse than that of K-line ( +) group (n = 57, 50.6%, p<0.05). Among 11 K-line (-) patients, 7 were disc type and 4 were osseous type. Over the period of follow-up, the disc type K-line (-) patients changed to K-line ( +) and showed significantly better recovery rate (27.6%) compared to the osseous type K-line (-) group (5.0%, p < 0.05).

CONCLUSION

The present of this study indicate that K-line may have a predictive value for clinical outcome in patients undergoing LP for CSM. K-line (-) of osseous type was worse than k-line (-) of disc type.

Surgical and Functional Outcomes of Expansive Open-Door Laminoplasty for Patients With Mild Kyphotic Cervical Alignment

Objective

To evaluate the cervical dynamics, neurological function, pain, and quality of life in patients with mild cervical kyphotic alignment who underwent expansive unilateral open-door laminoplasty (ELAP).

Methods

In this retrospective single-center study, we reviewed the surgical outcomes of 80 patients with cervical spondylotic myelopathy who were followed for at least 2 years. The patients were categorized into the preoperative kyphotic group (C2–7 angle < 0°) and nonkyphotic group (angle ≥ 0°). We compared clinical information, radiographic parameters, Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) scores, and cervical Japanese Orthopaedic Association (JOA) scores between the groups.

Results

The kyphotic and nonkyphotic groups comprised 17 and 63 patients, respectively. The preoperative C2–7 angles were -3.7° in the kyphotic group and 15.4° in the nonkyphotic group (p<0.01). In the kyphotic group, kyphotic alignment improved to lordosis at the final follow-up (2.6°, p=0.01). The preoperative (16.4° vs. 24.1°, p<0.01) and final-follow-up (17.8° vs. 24.5°, p<0.01) C7 slopes were significantly smaller in the kyphotic group. ELAP reduced pain in the arms or hands (p=0.02) and improved the JOA scores (p<0.01) in the kyphotic group. Patient-reported outcomes assessed using the JOACMEQ showed comparable effective rates in both groups.

Conclusion

Patients with mild cervical kyphosis showed smaller C7 slopes as a compensatory mechanism. Kyphotic angles significantly improved to lordosis after ELAP, resulting in favorable clinical outcomes. ELAP is a useful surgical option for patients even if they present mild kyphotic cervical angles.

Association between muscle morphology changes, cervical spine degeneration and clinical features in patients with chronic nonspecific neck pain: a magnetic resonance imaging analysis

PURPOSE

The primary objective of the present study was to investigate the correlations among cervical paraspinal muscle morphology changes (fatty infiltration (FI) and muscle atrophy), cervical degeneration and clinical features in patients with chronic nonspecific neck pain (CNSNP).

METHODS

The magnetic resonance imaging (MRI) data of 55 consecutive patients (average age 35.80) with CNSNP were analyzed in this cross-sectional study. Muscle morphology changes in seven groups of paraspinal muscles, indicated by the adjusted cross-sectional area (aCSA) and FI ratio (FI%), were measured from C3/4 to C6/7. The correlations of these changes with disc degeneration, cervical balance (C2-7 angle and cervical alignment) and clinical features (severity of neck pain and related disability and the frequency of acute neck pain (ANP) recurrence) were evaluated.

RESULTS

Significant correlations between FI% and aCSA and the grade of disc degeneration were observed in specific muscle groups at each level (p<0.05). Morphological changes in the deep extensors and superficial paraspinal muscles were significantly associated with cervical balance parameters (p<0.05). The FI% showed a significant positive correlation, while aCSA showed a significant negative correlation with the severity of neck pain and related disability (p<0.05). Correlations between morphological changes and the frequency of ANP recurrence were also present for some muscles (p<0.05).

CONCLUSION

Correlations among muscle morphology changes, cervical degeneration and clinical features were established for patients with CNSNP, and muscle volume changes and FI might affect CNSNP in diverse manners through different paraspinal muscle groups. These results implicated the complex contribution of muscle morphological changes to cervical degeneration and the clinical course of CNSNP.

Preoperative Radiological Parameters to Predict Clinical and Radiological Outcomes after Laminoplasty

Many studies have focused on pre-operative sagittal alignment parameters which could predict poor clinical or radiological outcomes after laminoplasty. However, the influx of too many new factors causes confusion. This study reviewed sagittal alignment parameters, predictive of clinical or radiological outcomes, in the literature. Preoperative kyphotic alignment was initially proposed as a predictor of clinical outcomes. The clinical significance of the K-line and K-line variants also has been studied. Sagittal vertical axis, T1 slope (T1s), T1s-cervical lordosis (CL), anterolisthesis, local kyphosis, the longitudinal distance index, and range of motion were proposed to have relationships with clinical outcomes. The relationship between loss of cervical lordosis (LCL) and T1s has been widely studied, but controversy remains. Extension function, the ratio of CL to T1s (CL/T1s), and Sharma classification were recently proposed as LCL predictors. In predicting postoperative kyphosis, T1s cannot predict postoperative kyphosis, but a low CL/T1s ratio was associated with postoperative kyphosis.

Spinal Cord Drift Following Laminoplasty Versus Laminectomy and Fusion for Cervical Spondylotic Myelopathy

BACKGROUND

Cervical laminoplasty and laminectomy and fusion (LF) are posterior-based surgical techniques for the surgical treatment of cervical spondylotic myelopathy (CSM). Interestingly, the comparative amount of spinal cord drift obtained from these procedures has not been extensively described. The purpose of this study is to compare spinal cord drift between cervical laminoplasty and LF in patients with CSM.

METHODS

The laminoplasty group consisted of 22 patients, and the LF group consisted of 44 patients. Preoperative and postoperative alignment was measured using the Cobb angle (C2-C7). Spinal cord position was measured on axial T2-magnetic resonance imaging of the cervical spine preoperatively and postoperatively. Spinal cord drift was quantified by subtracting preoperative values from postoperative values. Functional improvement was assessed using the modified Japanese Orthopaedic Association (mJOA) score.

RESULTS

Mean spinal cord drift was higher following LF compared to laminoplasty (2.70 vs 1.71 mm, P < .01). Using logistic regression analysis, there was no correlation between sagittal alignment and spinal cord drift. Both groups showed an improvement in mJOA scores postoperatively compared to their preoperative values (laminoplasty, +2.0, P = .012; LF, +2.4, P < .01). However, there was no difference in mJOA score improvement postoperatively between both groups (P = .482).

CONCLUSIONS

This study demonstrates that patients who had LF for CSM achieved more spinal cord drift postoperatively compared to those who had laminoplasty. However, the increased drift did not translate into superior functional outcome as measured by the mJOA score.

LEVEL OF EVIDENCE

3.

CLINICAL RELEVANCE

Spinal cord drift following LF may differ from laminoplasty in patients undergoing surgery for CSM. This finding should be considered when assessing CSM patients for surgical intervention.

The R-line: A New Imaging Index for Decision Making Regarding C2 Lamina Decompression in Cervical Ossification of the Posterior Longitudinal Ligament

Objective

The optimal treatment modality for cervical ossification of the posterior longitudinal ligament (OPLL) including the C2 level remains controversial. Cervical laminoplasty is a widely accepted considering of advantages such as development of few postoperative complications, including kyphosis or neck pain. We encountered seven patients with postoperative disabilities resulting from incomplete decompression after undercutting of the C2 lamina. Based on this experience, we developed a new index to determine the degree of decompression in cervical OPLL—the rostral line (R-line).

Methods

Total of 79 consecutive patients who underwent posterior decompression of cervical OPLL were included in this study. Mean age at the time of operation, the C2-C7 cervical lordotic angle and OPLL thickness at the most stenotic level of the spinal canal, and preoperative/postoperative Japanese Orthopedic Association score was checked in these group. We compared the correspondence between the degree of C2 lamina decompression using the R-line and actual degree of decompression.

Results

In all patients, the R-line touched the upper half of the C2 lamina on preoperative magnetic resonance imaging (MRI). The C2-C3 local segment lordotic angle and maximal degree of spinal cord compression by OPLL were independently correlated to postoperative C2 cord shifting. This result indicates that the R-line is a valid indicator to determine the degree of C2 lamina decompression in OPLL extending to the C2 level.

Conclusion

The results showed that undercutting the C2 lamina can result in incomplete spinal cord decompression and poor clinical outcome if the R-line touches the upper half of the C2 lamina on preoperative MRI.

Analysis of Cervical Spine Alignment and its Relationship with Other Spinopelvic Parameters After Laminoplasty in Patients with Degenerative Cervical Myelopathy

For patients with kyphosis of the cervical spine, laminoplasty is usually incapable of improving neurological symptoms as it worsens kyphotic alignment. Thus, laminoplasty is not recommended in the presence of kyphotic alignment. Nevertheless, laminoplasty may be selected for myelopathy due to multiple-segment intervertebral disc herniation or ossification of posterior longitudinal ligament despite kyphotic alignment. This study examined whether cervical alignment influences surgical outcomes. Cervical alignment before the surgery was classified into lordosis and non-lordosis, and the non-lordosis group was subclassified into reducible and non-reducible groups to determine the change in cervical alignment before and after the surgery and to analyze its relationship with spinopelvic parameters. The lordosis group showed an increase in upper cervical motion (C0-2 Range of Motion (ROM), C0-2ROM/C0-7ROM) after surgery, while the non-lordosis group exhibited a decrease in C2-7ROM and C0-7ROM. The C0-2ROM was maintained without any reduction in the reducible group, while there was no significant change in cervical alignment and ROM of the non-reducible group. None of these changes showed significant association with the spinopelvic parameters of other sites. However, having a non-reducible type non-lordosis is not a proper indication for laminoplasty, as it does not change the alignment after surgery. Therefore, cervical alignment and reducibility should be identified before surgery.

Short Monocortical Screws at C4-C6 Lateral Masses as Novel Mid-cervical Anchor in Cervical Laminoplasty with Instrumented Fusion: Surgical Outcomes Compared with C5 Pedicle Screws as Mid-cervical Anchor

Introduction

Methods

Results

Conclusions

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.

What Are the Important Predictors of Postoperative Functional Recovery in Patients With Cervical OPLL? Results of a Multivariate Analysis

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The objective of this study was to identify important predictors of poor functional recovery in patients undergoing surgery for cervical ossification of the posterior longitudinal ligament (OPLL).

METHODS

This was a retrospective cohort study of 142 OPLL patients with laminoplasty; 135 had complete radiographical data and were followed up for ≥2 years. The following OPLL characteristics were compared between patients with "good" and "poor" outcomes (Japanese Orthopedic Association [JOA] recovery rate ≥50% and <50%, respectively): number of ossified levels, OPLL classification, ossification shape, K-line, canal-occupying ratio, and increased magnetic resonance imaging (MRI) signal intensity. Predictors of functional recovery were identified.

RESULTS

Pre- and postoperative (2 years following surgery) JOA scores were 10.6 ± 2.9 and 14.1 ± 2.2, respectively, indicating significant improvement following laminoplasty (P < .001). The average JOA recovery rate was 53.4% ± 34.7%, with 81 (60.0%) and 54 (40.0%) patients in the better and poorer neurological outcome groups, respectively. The canal occupation ratio of OPLL ≤60%/>60% were 117 (86.7%) and 18 (13.3%) patients, respectively. In the stepwise logistic regression analysis, an occupation ratio greater than 60% was identified as a significant factor for poor postoperative neurological outcome (relative risk, 4.82; 95% confidential interval, 1.61-14.46, P = .005).

CONCLUSIONS

This multivariate analysis demonstrated a large size OPLL (occupying ratio >60%) was associated with a risk of poor neurological recovery roughly 5 times greater, and therefore other types of surgery are recommended in cases with such a ratio.

The Dural Tube Continues to Expand after Muscle-Preserving Cervical Laminectomy

Introduction

The purpose of this study was to elucidate the duration for which the dural tube continues to expand after muscle-preserving cervical laminectomy and the extent to which the expansion affects surgical outcomes.

Methods

We analyzed 83 patients with cervical myelopathy who underwent muscle-preserving selective laminectomy of three consecutive laminae between C4 and C6. On the lateral radiographs, parameters considered were C2-7 Cobb angles, range of flexion-extension neck motions, and C2-7 sagittal vertical axis. Neck alignment was classified into four types with lateral radiographs. Anteroposterior (AP) diameter of the dural tube was measured at mid-level of the C5 vertebral body on T2 sagittal image. Expansion ratio (ER) was defined as the extent of expansion at a particular time divided by the final extent of expansion of the dural tube diameter. Operative outcomes were examined using the Japanese Orthopaedic Association scores.

Results

The mean age was 62.3 years, and the mean follow-up period was 2 years and 9 months. AP diameter of the dural tube had been expanding until 1-year after surgery. ER in cases with kyphosis was lower at 6 months than that in cases without kyphosis, indicating that the speed of dural expansion was slower in cases with kyphosis. There was no correlation between the extent of expansion of the dural tube and neurological recovery.

Conclusions

The dural tube continued to expand for approximately 1-year after surgery. The dural tube of patients with kyphosis slowly expanded possibly because of the hardness of the dura mater. A small extent of dural expansion does not necessarily indicate bad surgical outcomes.

Fixed Neck Position in Multilevel Cervical Posterior Decompression and Fusion to Reduce Postoperative Disturbances of Cervical Spine Function

Introduction

Difficulties with neck mobility often interfere with patients' activities of daily living (ADL) after cervical posterior spine surgery. The range of motion of the cervical spine decreases markedly after multilevel cervical posterior decompression and fusion (PDF). However, details regarding the limitations of cervical spine function due to postoperative reduced neck mobility after multilevel PDF are as yet unclarified. The present study aimed to clarify the quality of life and its related factors after PDF, and the optimal fixed neck position in multilevel PDF that minimizes the limitations of ADL accompanying markedly reduced postoperative neck mobility.

Methods

Limitations of ADL involving neck extension, rotation, and flexion were investigated in 32 consecutive patients who underwent C2-T1 PDF using the responses to the cervical spine function domain of the Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). The EuroQol 5 Dimension, Japanese Orthopedic Association score, and five domains of the JOACMEQ were also investigated. We investigated the risk factors regarding the fixed neck position in PDF for the impossibility to perform ADL involving each of three movements using cut-off values obtained from receiver-operating characteristic curves.

Results

Postoperative comprehensive quality of life was significantly related to neurological improvements and to poor outcomes of cervical spine function after PDF. The significant risk factors for impossibility to perform ADL involving neck rotation were a C2-C7 lordotic angle ≥ 6° (P = 0.0057) or a proportion coefficient of C2-T1 tilt angle/C2-C7 lordotic angle ≤ 1.8 (P = 0.0024). There were no significant risk factors for impossibility to perform ADL involving neck extension or flexion.

Conclusions

The optimal fixed neck position in C2-T1 PDF to reduce postoperative limitations of ADL involving neck mobility is a C2-C7 lordotic angle of less than 6°, or a C2-T1 tilt angle (°) of greater than 1.8 × the C2-C7 lordotic angle (°).

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

Introduction

The purpose of this study was to investigate the relationship between postoperative enlargement of the dural sac cross-sectional area at the symptomatic level and neurological improvements after laminoplasty.

Methods

The cross-sectional areas of the dural sac at the symptomatic level before and after laminoplasty and the expansion ratio (post-/preoperative cross-sectional area) were measured using magnetic resonance imaging in patients with ossification of the posterior longitudinal ligament (OPLL) (n = 25) and patients with cervical spondylotic myelopathy (CSM) (n = 49). The relationships between the expansion ratio and the Japanese Orthopedic Association (JOA) score, JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and postoperative laminae morphology were investigated.

Results

In the OPLL group, the expansion ratio was significantly positively correlated with the postoperative JOA score (P = 0.025), recovery rate of the JOA score (P = 0.026), and postoperative change in lower extremity sensory function according to the JOA score (P = 0.0375); furthermore, patients whose JOACMEQ responses indicated positive outcomes for lower extremity function had a significantly larger expansion ratio than patients with negative results (P = 0.027). In the CSM group, the expansion ratio showed no correlation with the JOA and JOACMEQ scores. The expansion ratio was significantly positively correlated with the width between bilateral gutters in both CSM (P = 0.025) and OPLL (P = 0.0451). In the OPLL group, the expansion ratio in those with a gutter position of less than 0.8 was significantly smaller than that those with a gutter position of more than 0.8 (P = 0.0156). However, there was no correlation between the gutter position and the recovery rate of the JOA score.

Conclusions

In OPLL, insufficient enlargement of the cross-sectional area of the dural sac at the symptomatic level leads to poor neurological improvements after laminoplasty.

Efficacy of Laminoplasty in Patients with Cervical Kyphosis

Background

The efficacy of laminoplasty in patients with cervical kyphosis is controversial. The purpose of this study was to investigate the impact of the initial pathogenesis on the clinical outcomes of laminoplasty in patients with cervical kyphosis.

Material/Methods

A total of 137 patients with cervical spondylotic myelopathy (CSM) or ossification of the posterior longitudinal ligament (OPLL) underwent laminoplasty from April 2013 to May 2015. The patients were divided into the following 4 groups: lordosis with CSM (LC), kyphosis with CSM (KC), lordosis with OPLL (LO), and kyphosis with OPLL (KO). The clinical outcome measures included the visual analogue scale (VAS) and modified Japanese Orthopedic Association (mJOA) scores, the range of motion (ROM), and the cervical global angle (CGA).

Results

The mean VAS and mJOA scores improved significantly in all groups after surgery. The changes in VAS and mJOA scores were significantly smaller, and the JOA recovery rate was significantly lower, in the KC group than in the LC and KO groups. The mean change in the CGA was greatest in the KC group (>8° towards kyphosis). The preoperative ROM was negatively correlated with the change in CGA and the JOA recovery rate in the KO and KC groups.

Conclusions

We found that laminoplasty is suitable for patients with cervical lordosis and those with mild cervical kyphosis and OPLL, but is not recommended for patients with kyphosis and CSM, particularly those with a large ROM preoperatively.

Prognostic Value of Lordosis Decrease in Radiographic Adjacent Segment Pathology After Anterior Cervical Corpectomy and Fusion

While cervical lordosis alteration is not uncommon after anterior cervical arthrodesis, its influence on radiological adjacent segment pathology (RASP) is still unclear. Biomechanical changes induced by arthrodesis may contribute to ASP onset. To investigate the correlation between cervical lordosis decrease and RASP onset after anterior cervical corpectomy and fusion (ACCF) and to determine its biomechanical effect on adjacent segments after surgery, 80 CSM patients treated with ACCF were retrospectively studied, and a baseline finite element model of the cervical spine as well as post-operation models with normal and decreased lordosis were established and validated. We found that post-operative lordosis decrease was prognostic in predicting RASP onset, with the hazard ratio of 0.45. In the FE models, ROM at the adjacent segment increased after surgery, and the increase was greater in the model with decreased lordosis. Thus, post-operative cervical lordosis change significantly correlated with RASP occurrence, and it may be of prognostic value. The biomechanical changes induced by lordosis change at the adjacent segments after corpectomy may be one of the mechanisms for this phenomenon. Restoring a well lordotic cervical spine after corpectomy may reduce RASP occurrence and be beneficial to long-term surgical outcomes.

Cervical Paraspinal Muscle Atrophy Rates Following Laminoplasty and Laminectomy with Fusion for Cervical Spondylotic Myelopathy

BACKGROUND

Cervical spondylotic myelopathy (CSM) is a disorder that can cause neurologic deterioration. Studies on paraspinal muscular atrophy (PMA) in the lumbar spine have shown that these changes are caused by several perioperative factors. It is possible that PMA in the cervical spine could behave similarly. In this retrospective study, we compared the degree of PMA after laminoplasty versus laminectomy and fusion (LF) using a standard posterior approach to the cervical spine.

METHODS

18 laminoplasty and 43 LF patients were included in this study. For each patient, preoperative and postoperative MRI files were obtained and transferred into OsiriX imaging software. Atrophy rate was obtained and reported as percentage change in cross-sectional area of the cervical paraspinal muscles from preoperative to postoperative imaging.

RESULTS

Mean cross-sectional cervical muscle atrophy rates were 6% and 13.1% for laminoplasty and LF, respectively, representing a 2.19 times increase in the degree of atrophy (P < 0.001). Independently, LF was associated with a 5.84% increase in the rate of PMA (P = 0.03). Involvement of C3 as the cephalad surgical level was associated with a 5.78% decrease in the rate of PMA (P = 0.03). For each degree increase in postoperative Cobb angle, there was a 0.66% decrease in the rate of PMA (P = 0.02).

CONCLUSION

PMA should be part of the decision making process when a posterior approach is considered, inasmuch as this study demonstrates that cervical laminoplasty was associated with significantly lower rates of PMA compared with cervical laminectomy and fusion. Additionally, these results suggest that minimizing PMA may help preserve cervical lordosis.

Does Segmental Kyphosis Affect Surgical Outcome after a Posterior Decompressive Laminectomy in Multisegmental Cervical Spondylotic Myelopathy?

Study Design

Retrospective analysis.

Purpose

To compare results of laminectomy in multisegmental compressive cervical myelopathy (CSM) with lordosis versus segmental kyphosis.

Overview of Literature

Laminectomy is an established procedure for decompression in CSM with cervical lordosis. However in patients with segmental kyphosis, it is associated with risk of progression of kyphosis and poor outcome. Whether this loss of sagittal alignment affects functional outcome is not clear.

Methods

We retrospectively reviewed 68 patients who underwent laminectomy for CSM from 1998 to 2009. As per preoperative magnetic resonance images, 36 patients had preoperative lordosis (Group 1) and 32 had segmental kyphosis (Group 2). We studied age at the time of surgery, duration of preoperative symptoms, recovery rate, magnitude of postoperative backward shifting of spinal cord and loss of sagittal alignment.

Results

Mean follow up was 5.05 years (range, 2–13 years) and mean age at the time of surgery 61.88 years. Group 1 had 20 men and 16 women and Group 2 had 19 men and 13 women. Mean recovery rate in Group 1 was 60.32%, in Group 2 was 63.7% without any statistical difference (p-value 0.21, one tailed analysis of variance). Two patients of Group 1 had loss of cervical lordosis by five degrees. In Group 2 seven patients had progression of segmental kyphosis by 5–10 degrees and two patients by more than 10 degrees. Mean cord shift was more in Group 1 (mean, 2.41 mm) as compared to Group 2 (mean, –1.97 mm) but it had no correlation to recovery rate. Patients with younger age (mean, 57 years) and less duration of preoperative symptoms (mean, 4.86 years) had better recovery rate (75%).

Conclusions

Clinical outcome in CSM is not related to preoperative cervical spine alignment. Thus, lordosis is not mandatory for planning laminectomy in CSM. Good outcome is expected in younger patients operated earliest after onset of symptoms.

Addressing Stretch Myelopathy in Multilevel Cervical Kyphosis with Posterior Surgery Using Cervical Pedicle Screws

Study Design

Technique description and retrospective data analysis.

Purpose

To describe the technique of cervical kyphosis correction with partial facetectomies and evaluate the outcome of single-stage posterior decompression and kyphosis correction in multilevel cervical myelopathy.

Overview of Literature

Kyphosis correction in multilevel cervical myelopathy involves anterior and posterior surgery. With the advent of cervical pedicle screw-rod instrumentation, single-stage posterior kyphosis correction is feasible and can address stretch myelopathy by posterior shortening.

Methods

Nine patients underwent single-stage posterior decompression and kyphosis correction for multilevel cervical myelopathy using cervical pedicle screw instrumentation from March 2011 to February 2014 and were evaluated preoperatively and postoperatively with modified Japanese Orthopaedic Association (mJOA) scoring and computed tomography scans for radiological measurements. Kyphosis assessment was made with Ishihara curvature index and C2–C7 Cobb's angle. The linear length of the spinal canal and the actual spinal canal length were also evaluated. The average follow-up was 40.56 months (range, 20 to 53 months).

Results

The average preoperative C2–7 Cobb's angle of 6.3° (1° to 12°) improved to 2° (10° to −9°). Ishihara index improved from −15.8% (−30.5% to −4.7%) to −3.66% (−14.5% to +12.6%). The actual spinal canal length decreased from 83.64 mm (range, 76.8 to 91.82 mm) to 82.68 mm (range, 75.85 to 90.78 mm). The preoperative mJOA score of 7.8 (range, 3 to 11) improved to 15.0 (range, 13 to 17).

Conclusions

Single-stage posterior decompression and kyphosis correction using cervical pedicle screws for multilevel cervical myelopathy may address stretch myelopathy, in addition to decompression in the transverse plane. However, cervical lordosis was not achieved with this method as predictably as by the anterior approach. The present study shows evidence of mild shortening of cervical spinal canal and a positive correlation between canal shortening and clinical improvement.

K-line (-) in the Neck-Flexed Position in Patients With Ossification of the Posterior Longitudinal Ligament Is a Risk Factor for Poor Clinical Outcome After Cervical Laminoplasty

STUDY DESIGN

Retrospective study comparing postoperative clinical outcomes after cervical laminoplasty between K-line (-) ossification of the posterior longitudinal ligament (OPLL) and K-line (+) OPLL in the neck-flexed position.

OBJECTIVE

To investigate postoperative outcomes using Japanese Orthopedic Association (JOA) scores, and grip-and-release (GR) and foot-tap (FT) test scores after laminoplasty in patients with K-line (-) OPLL in the neck-flexed position.

SUMMARY OF BACKGROUND DATA

Cervical laminoplasty has been reported to lead to poor outcomes in K-line (-) OPLL and good outcomes in K-line (+) OPLL. The cervical spine, however, continues moving in the extension and flexion direction after laminoplasty.

METHODS

Patients with cervical myelopathy were divided into K-line (+) and (-) in the neck-flexed position. We compared postoperative outcomes after cervical laminoplasty using recovery rate, as assessed by the JOA score and degree of improvement in the six JOA score items, and performance, as assessed by GR and (FT) tests, between patients with K-line (+) OPLL (n = 18) and K-line (-) OPLL (n = 23) in the neck-flexed position.

RESULTS

Recovery rate of JOA score (23.8%) of patients in the K-line (-) group was significantly lower (P = 0.028) than that (46.3%) of K-line (+) group in the neck-flexed position. In the K-line (+) group, significant improvements were seen in all JOA-score items except bladder function; however, in the K-line (-) group, improvements were seen only in upper- and the lower-extremity sensory functions. In the K-line (+) group, mean GR and FT tests significantly improved, but in the K-line (-) group, only mean FT test significantly improved.

CONCLUSION

The K-line (-) OPLL in the neck-flexed position is a risk factor for poor clinical outcome after cervical laminoplasty.

LEVEL OF EVIDENCE

4.

Scarcity of Implants Has Partially Replaced Cervical Spondylotic Myelopathy Decompression and Instrumented Fusion with Implant-Less Expansile Cervical Laminoplasty: Poverty Teaches all the Arts

OBJECTIVE

The scarcity of implants during the economic crisis partially has replaced decompression and instrumented fusion for the treatment of cervical spondylotic myelopathy with implant-less expansile cervical laminoplasty (ECL). The aim of the study was to compare the results obtained with instrumented anterior cervical corpectomy and fusion with implant-less ECL.

METHODS

Patients suffering from cervical spondylotic myelopathy Nurick 3-5 with preoperative tethering and postoperative untethering were included. Exclusion criterion was kyphosis more than 10°. Patients were assessed according to 30-meter walking track (30mWT), Nurick, and modified Japanese Orthopaedic Association scale scores. Kinematic magnetic resonance imaging 3-dimensional subaxial spinal cord reconstructions were 3 dimensionally modeled to confirm preoperative pincer clamping and follow-up unclamping to measure subaxial spinal cord length and pia envelope area (PEA).

RESULTS

A total of 35 patients divided in the ECL (n = 19) and the anterior cervical corpectomy and fusion (n = 16) groups were selected from 534 patients operated on between September 1, 2008, and August 31, 2013 as the result of degenerative cervical disorders. Patients improved according to Nurick and modified Japanese Orthopaedic Association scores without differences between groups. Follow-up 30mWT analysis showed greater decrease in steps number and time in ECL group, creating the basis for further imaging analysis. Magnetic resonance imaging analysis showed that spinal cord length (mm) shortened more (4.47 ± 1.87 vs. 1.5 ± 2.5, t = -4.02; P = 0.0003) and PEA (mm²) shrank more (95.58 ± 43.73 vs. 22.94 ± 33.11, t = -5.45, P < 0.0001) in the ECL group. Multivariate logistic analysis showed that Δ 30mWT-time and Δ PEA were a very predictive model when area under the receiver operating characteristic curve is 0.98.

CONCLUSIONS

Our results created a nidus for further research of postdecompression spinal cord relaxation.

Image analysis of open-door laminoplasty for cervical spondylotic myelopathy: comparing the influence of cord morphology and spine alignment

OBJECTIVES

Previous studies have identified the factors affecting the surgical outcome of cervical spondylotic myelopathy (CSM) following laminoplasty. Nonetheless, the effect of these factors remains controversial. It is unknown about the association between pre-operative cervical spinal cord morphology and post-operative imaging result following laminoplasty. The goal of this study is to analyze the impact of pre-operative cervical spinal cord morphology on post-operative imaging in patients with CSM.

METHODS

Twenty-six patients with CSM undergoing open-door laminoplasty were classified according to pre-operative cervical spine bony alignment and cervical spinal cord morphology, and the results were evaluated in terms of post-operative spinal cord posterior drift, and post-operative expansion of the antero-posterior dura diameter.

RESULTS

By the result of study, pre-operative spinal cord morphology was an effective classification in predicting surgical outcome - patients with anterior convexity type, description of cervical spinal cord morphology, had more spinal cord posterior migration than those with neutral or posterior convexity type after open-door laminoplasty. Otherwise, the interesting finding was that cervical spine Cobb's angle had an impact on post-operative spinal cord posterior drift in patients with neutral or posterior convexity type spinal cord morphology - the degree of kyphosis was inversely proportional to the distance of post-operative spinal cord posterior drift, but not in the anterior convexity type.

CONCLUSIONS

These findings supported that pre-operative cervical spinal cord morphology may be used as screening for patients undergoing laminoplasty. Patients having neutral or posterior convexity type spinal cord morphology accompanied with kyphotic deformity were not suitable candidates for laminoplasty.

Outcomes of surgical intervention for cervical spondylotic myelopathy accompanying local kyphosis (comparison between laminoplasty alone and posterior reconstruction surgery using the screw-rod system)

PURPOSE

The surgical strategy for cervical spondylotic myelopathy (CSM) accompanying local kyphosis is controversial. The purpose of the present study was to compare and evaluate the outcomes of two types of surgery for CSM accompanying local kyphosis: (1) laminoplasty alone (LP) and (2) posterior reconstruction surgery (PR) in which we corrected the local kyphosis using a pedicle screw or lateral mass screw.

METHODS

Sixty patients who presented with local kyphosis exceeding 5° were enrolled. LP and PR were each performed on a group of 30 of these patients; 30 CSM patients without local kyphosis, who had undergone LP, were used as controls. The follow-up period was 2 years or longer. Preoperative local kyphosis angles in LP and PR were 8.3° ± 4.4° and 8.8° ± 5.7°, respectively. Preoperative C2-7 angles in LP, PR and controls were -1.7° ± 9.6°, -0.4° ± 7.2° and -12.0° ± 5.6°, respectively. The recovery rate of the JOA score, local kyphosis angle and C2-7 angle at post-op and follow-up were compared between the groups.

RESULTS

The recovery rate of the JOA score in the LP group (32.6 %) was significantly worse than that in the PR group (44.5 %) and that of controls (53.8 %). Local kyphosis angles in the PR and LP groups at follow-up were 4.0° ± 8.6° and 8.0° ± 6.0°, respectively. However, although the C2-7 angle at follow-up was improved to -11.1° ± 12.7° in PR, and maintained at -11.6° ± 6.2° in controls, it deteriorated to 0.5° ± 12.7° in LP.

CONCLUSIONS

The present study is the first to compare the outcomes between LP alone and PR for CSM accompanying local kyphosis. It revealed that PR resulted in a better clinical outcome than did LP alone. This result may be due to reduction of local kyphosis, stabilization of the unstable segment, and/or the maintenance of C2-7 angle until follow-up in the PR group.

Is cervical lordosis relevant in laminoplasty?

BACKGROUND CONTEXT

Laminoplasty aims to decompress the spinal cord and stabilize the cervical spine in patients with multilevel cervical lesions. Not every patient with cervical compressive myelopathy is a good candidate for laminoplasty. Most studies recommend that neutral or kyphotic alignments are contraindications for laminoplasty. However, cervical sagittal alignment does not have a strong and consistent effect on the clinical outcomes of laminoplasty. Moreover, many reports on the effect of cervical sagittal alignment did not designate the ideal definition of alignment and used different definitions of lordosis.

PURPOSE

To identify the effect of preoperative cervical alignment according to two different definitions after midline splitting double-door laminoplasty.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

From August 2008 to September 2010, 58 patients were diagnosed with cervical myelopathy and treated with midline splitting double-door laminoplasty.

OUTCOME MEASURES

The clinical results were assessed with the modified Japanese Orthopedic Association (JOA) score, neck disability index (NDI), and visual analog scale (VAS) and were compared to analyze the rate of change between preoperative and postoperative values. Postoperative radiological results at the final follow-up examinations were compared between groups to obtain the change in range of motion and sagittal alignment.

METHOD

The effect of cervical alignment on JOA, NDI, and VAS scales and also on change of alignment and change of range of motion (ROM) at the final follow-up examinations was analyzed statistically between two groups according to two different definitions such as Toyama classification and Cobb angle.

RESULTS

No difference was found between the two groups according to Toyama classification in terms of the postoperative improvement rate of the modified JOA score (p=.086), decreasing rate of the VAS (p=.940) or NDI (p=.211), postoperatively. Additionally, no difference was found for the decreasing rate of ROM (p=.427) or sagittal alignment (p=.864) based on the radiological evaluation results. Also, there was no difference between two groups according to Cobb angle in terms of the modified JOA score (p=.743), VAS (p=.548), or NDI (p=.32), postoperatively. Additionally, no difference was found for the ROM (p=1.000) or sagittal alignment (p=.440) based on the radiological evaluation results.

CONCLUSIONS

Despite nonlordosis cervical sagittal alignment, double-door laminoplasty would be effective for patients with cervical myelopathy because of cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament. Furthermore, sagittal alignment is not the absolute and sole factor that surgeons should consider when determining the optimal treatment strategy.

Posterior spinal decompression, stabilization and arthrodesis in Nigerian adults: Profile and outcome

Background:

The availability of intraoperative fluoroscopy and improved access to varieties of spinal titanium implants has revived posterior spinal stabilization techniques with their distinct advantages. Our aim is to describe the profile of various spine pathologies requiring subaxial posterior spinal decompression, stabilization (using titanium implants), and arthrodesis, and to determine the rate of postoperative complications and factors affecting outcome.

Materials and Methods:

This is a prospective single institution study of consecutive adult patients seen during the study period. Data collected included the patients’ demographics, radiological findings, indication for surgery, surgical procedure, operation time, intraoperative blood loss, and postoperative complications.

Results:

There were 26 patients (15 males and 11 females). Their ages ranged between 24 and 78 years (median = 42 years). The most common indications for surgery were spinal trauma and degenerative spine disease (24 patients). The region that was most commonly stabilized was the lumbar- 12 cases (46.2%). No patients experienced neural or vascular injury as a result of screw position; likewise no patient had screw loosening. There was a case each of superficial surgical site infection and transient cerebrospinal fluid leak but no case of implant failure was encountered. The outcome was significantly associated with the etiology (0.030) of the indication for surgery and preoperative power grade (0.000).

Conclusion:

Spinal trauma and degenerative spine disease are the two most common indications for posterior spinal decompression, stabilization and fusion in our center. It is associated with acceptable postoperative complication rate when done under fluoroscopic guidance. Outcome is related more to the preoperative neurological deficit and etiology of the indication for surgical stabilization.

Avaliação das técnicas cirúrgicas para tratamento da mielorradiculopatia espondilótica cervical

OBJETIVO: Avaliar a eficácia do tratamento cirúrgico da mielorradiculopatia espondilótica cervical na produção de melhora neurológica pós-operatória, aferida em pontos pela escala da JOA e taxa de recuperação e as complicações do tratamento. MÉTODOS: Análise dos prontuários e os exames de imagem de 200 indivíduos submetidos a tratamento cirúrgico da mielorradiculopatia cervical no HC-FMUSP, no período de janeiro de 1993 a janeiro de 2007. A avaliação clínica foi quantificada pela escala da JOA, com média de segmento de 06 anos e 08 meses. RESULTADOS: Evidenciou-se melhora neurológica pós-operatória nas vias anterior e posterior, exceto nas laminectomias sem fusão, onde houve piora neurológica tardia. A via anterior mostrou um significante maior índice de complicações, relacionados a déficit de fusão intervertebral, deslocamento de enxerto, síndrome de disco adjacente, disfonia, disfagia, o mau posicionamento de enxerto e placas, lesão de raiz nervosa e significativo maior índice de re-intervenção cirúrgica. Na via posterior maior ocorrência de instabilidade em cifose pós-operatória na laminectomia, não sendo observada na laminoplastia, esta última com índices semelhantes aos encontrados na via anterior. Não houve melhora da dor axial nas laminoplastias e houve piora nas laminectomias, enquanto que nas discectomias e corpectomias houve significativa melhora do sintoma. CONCLUSÃO: As vias anterior e posterior foram eficazes em produzir melhora neurológica, exceto as laminectomias sem fusão. A via anterior produziu mais complicações, mas trata melhor a dor.

Anterior cervical multilevel decompression and fusion using fibular strut as revision surgery for failed cervical laminoplasty

STUDY DESIGN

Retrospective analyses of six cases.

OBJECTIVE

To describe six patients with previous failed laminoplasty who were subsequently managed by anterior cervical decompression and fusion (ACDF) using fibular strut as revision surgeries.

SUMMARY OF BACKGROUND DATA

While several complications and unsatisfactory results of cervical laminoplasty have been reported, there is no general consensus on how to best surgically treat these pathological conditions.

METHODS

Six patients, who had been treated by laminoplasty for cervical spondylotic myelopathy (n = 2) or ossification of posterior longitudinal ligament (OPLL, n = 4) and had unfavorable outcomes, underwent ACDF using autogenous fibular strut grafts. The pathological factors associated with the poor outcomes were intraforaminal spur, slip, spondylotic change, disc herniation, and increase of OPLL in size. Clinical outcomes were assessed by evaluating the modified Japanese Orthopedic Association score (JOA score) of cervical myelopathy, severity of radicular pains, axial pains, and perioperative complications. In addition, C2-7 angle and the presence of bony union were analyzed.

RESULTS

The revision ACDF significantly increased the mean ± SD. JOA score, from 10.3 ± 3.9 to 13.5 ± 2.7 points (p = 0.028), with a recovery rate of 47.1 ± 26.7%. Radicular pain and axial pain also improved. C2-7 angle was not changed significantly. Solid fusion was achieved in all patients at 12.2 ± 4.2 months after revision surgery.

CONCLUSION

ACDF with fibular strut graft was effective as a revision procedure for failed laminoplasty.

Effect of the decompressive extent on the magnitude of the spinal cord shift after expansive open-door laminoplasty

STUDY DESIGN

A retrospective study to analyze the effect of decompressive extent on the posterior shift of spinal cord after expansive open-door laminoplasty (ELAP).

OBJECTIVE

To investigate the effect of decompressive extent on cord shift distance after ELAP, and determine the morphologic limitations of posterior approach when the cervical alignment is lordotic or straight.

SUMMARY OF BACKGROUND DATA

It is still controversial on the effect of space available for spinal cord at the level cephalad to the decompression with cord shift. Moreover, there is less understanding regarding the significance of decompressive extent of laminoplasty in relation to spinal cord shift and clinical outcome.

METHODS

Preoperative and postoperative MRIs of 76 patients with a straight or lordotic cervical spine who had undergone cervical laminoplasty were reviewed and evaluated retrospectively. Radiographic parameters including cervical sagittal alignment, space available at the level cephalad, the thickness of compressive mass, and the average anterior subarachnoid space were measured. Laminoplasty was performed from C1 to C7 in 11 cases (CI group), C2 to C7 in 30 cases (CII group), and C3 to C7 in 35 cases (CIII group). According to whether the anterior indirect decompression was adequate or not, CII and CIII groups were further divided into two subgroups, the noncontact group in which the spinal cord was completely separated from the anterior compressive mass after laminoplasty, and the contact group in which there was residual cord compression after laminoplasty. The recovery rate that based on the Japanese Orthopedic Association score was calculated for each patient.

RESULTS

There were statistically significant differences in the average anterior subarachnoid space among CI, CII, and CIII groups (P < 0.05);the average anterior subarachnoid space was the largest in CI group, and the smallest in CIII group. The space available at the level cephalad had strong sigmoidal correlation with cord postoperative shift in CIII group (R = 0.91). A higher neurologic recovery rate (69% ± 20% vs. 29% ± 11%; P < 0.05) in the noncontact group after surgery than in the contact group, with a similar follow-up period.

CONCLUSION

The posterior decompression extent is a main factor affecting cord shift distance after laminoplasty in the context of a straightened or lordotic cervical curvature. The space available at the levels cephalad is a key factor to predict cord shift distance in laminoplasty from C3 to C7. Neurologic recovery rate after ELAP is affected by whether the anterior indirect decompression was adequate or not.

C5 palsy after cervical laminoplasty

We have reviewed 1858 patients who had undergone a cervical laminoplasty and identified 43 (2.3%) who had developed a C5 palsy with a MMT (MRC) grade of 0 to 2 in the deltoid, with or without involvement of the biceps, but with no loss of muscular strength in any other muscles. The clinical features and radiological findings of patients with (group P; 43 patients) and without (group C; 100 patients) C5 palsy were compared. CT scanning of group P revealed a significant narrowing of the intervertebral foramen of C5 (p < 0.005) and a larger superior articular process (p < 0.05). On MRI, the posterior shift of the spinal cord at C4–5 was significantly greater in group P, than in group C (p < 0.01).

This study is the first to correlate impairment of the C5 nerve root with a C5 palsy. It may be that early foraminotomy in susceptible individuals and the avoidance of tethering of the cord by excessive laminoplasty may prevent a post-operative palsy of the C5 nerve root.

Revision surgery following cervical laminoplasty: etiology and treatment strategies

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To identify the cause of failed open-door laminoplasty and to describe the surgical strategies for revision surgery.

SUMMARY OF BACKGROUND DATA

Although laminoplasty has become popular, few articles have addressed the cause of failed cervical laminoplasty requiring revision surgery.

METHODS

All patients who required revision surgery following open-door cervical laminoplasty were identified. Clinical data, method of surgical revision, time between surgeries, Nurick grade, radiologic parameters, and complications were analyzed. Laminoplasty failures were classified into 3 categories: "technique related," "inadequate symptomatic relief after treatment," or "recurrence of symptoms due to disease progression."

RESULTS

A total of 130 patients underwent cervical laminoplasty over a 10-year period (1996-2006), and 12 patients (9.2%) required revision surgery. The mean age was 50.7 years at the time of the index laminoplasty (range, 34-67 years) and 51.8 years (range, 35-70 years) at the time of the revision surgery. Mean duration of symptoms was 7.3 months before the index procedure (range, 2-17 months) and 5.6 months (range, 1-14 months) before revision surgery. The mean time interval between the index procedure and revision surgery was 16.6 months (range, 4-43 months). Of the 12 patients who required revision surgery, 5 had global lordosis of <10 degrees, 4 developed local kyphosis >13 degrees, and 5 had increased degenerative spondylolisthesis. Nonmyelopathic causes resulted in 50% of the revision surgery. Of 12 patients, 3 (25%) required revision surgery due to technique-related factors; 1 (8%) required surgery due to inadequate symptomatic relief after treatment; and 8 (67%) required revision surgery due to disease progression.

CONCLUSION

Of the 130 patients who underwent cervical laminoplasty over a 10-year period, 12 patients (9.2%) required revision surgery. Although laminoplasty is generally successful, failures due to disease progression, technique-related factors, and inadequate symptomatic relief after treatment can occur. Patients should, therefore, be counseled regarding the potential need for revision surgery when undergoing open-door laminoplasty.

Cervical spondylotic myelopathy associated with kyphosis or sagittal sigmoid alignment: outcome after anterior or posterior decompression

Object

The effects of sagittal kyphotic deformities or mechanical stress on the development of cervical spondylotic myelopathy, or the reduction and fusion of kyphotic sagittal alignment have not been consistently documented. The aim in this study was to determine the effects of kyphotic sagittal alignment of the cervical spine in terms of neurological morbidity and outcome after 2 types of surgical intervention.

Methods

The authors retrospectively reviewed the records of 476 patients who underwent cervical spine surgeries for spondylotic myelopathy between 1993 and 2006 at their university medical center. Among these were identified 43 patients—30 men and 13 women, with a mean age of 58.8 years—who had cervical kyphosis exceeding 10° on preoperative sagittal lateral radiographs obtained in the neutral position, and their cases were analyzed in this study. Anterior decompression with interbody fusion was conducted in 28 patients, and en bloc open-door C3–7 laminoplasty in 15 patients. Both pre- and postoperative neurological, radiographic, and MR imaging findings were assessed in both surgical groups.

Results

The mean preoperative kyphotic angle in all 43 patients was 15.9 ± 5.9° in the neutral position. Segmental instability was noted in 26 patients (61%) and reversed dynamic spinal canal stenosis at the level above the local kyphosis in 22 (51%). Preoperative T2-weighted MR images showed high-intensity signal within the cord at and around the level of maximal compression or segmental instability in 28 patients (65%). The mean kyphotic angle in both the neutral and flexion positions was significantly smaller at 4–6 weeks after surgery in the anterior spondylectomy group than in the laminoplasty group (p < 0.001). Furthermore, the angle in the neutral position was significantly smaller on follow-up in the anterior spondylectomy group than in the laminoplasty group (p = 0.034). The transverse area of the spinal cord was significantly larger in the anterior spondylectomy group than in the laminoplasty group on follow-up (p = 0.037). Preoperative neurological scores (assessed using the Japanese Orthopaedic Association scale) and improvement on follow-up ≥ 2 years after treatment (average 3.3 years) were not significantly different between the 2 groups; however, there was a significant difference in Japanese Orthopaedic Association score at 4–6 weeks postoperatively (p = 0.047).

Conclusions

Kyphotic deformity and mechanical stress in the cervical spine may play an important role in neurological dysfunction. In a select group of patients with kyphotic deformity ≥ 10°, adequate correction of local sagittal alignment may help to maximize the chance of neurological improvement.

The use of average Pavlov ratio to predict the risk of post operative upper limb palsy after posterior cervical decompression

Study Design

A retrospective study was conducted to study the post operative upper limb palsy after laminoplasty for cervical myelopathy.

Objective

To identify a reliable and simple preoperative radiological parameter in predicting the risk of post operative upper limb palsy.

Background

Post operative upper limb palsy is one of the causes of patient dissatisfaction after surgery. There had been no simple, standard preoperative radiological parameters reliably predict the occurrence of this problem.

Materials and methods

Seventy-four patients received posterior cervical decompression from 1998 to 2008. Medical record and preoperative radiological information were evaluated. Clinical presentations of the palsy were described. The relationship between the occurrence of palsy and different preoperative radiological information is analyzed.

Results

Eighteen patients (24.3%) presented with post operative upper limb palsy. Majority of patients presented with dysesthesia (17/18) and with deficit of the C5 segment (17/18). Ten patients presented with pure dysesthesia and 8 patients presented with mixed motor-sensory deficit and dysesthesia. Multilevel involvement was exclusively presented in patients with motor weakness. A longer duration of symptom (16.7 Vs 57.2 days) was noticed in patients in the motor deficit group. Average Pavlov ratio less then 0.65 (P = 0.027, Odds Ratio = 3.68) and compression at the C3/4 in preoperative MRI image (P = 0.025, Odds Ratio = 6) were significant risk factors for development of this problem.

Conclusion

Post operative upper limb palsy is not uncommon and thorough preoperative explanation is important. There is a spectrum of clinical presentation and patients with multi-level involvement and motor deficit are associated with poorer prognosis. Average Pavlov ratio < 0.65 and compression at C3/4 segment on preoperative MRI image are simple and reliable preoperative predictor for the development of this problem.

Risk factors for closure of lamina after open-door laminoplasty

Object

This retrospective study was conducted to evaluate the prevalence and clinical consequences of postoperative lamina closure after open-door laminoplasty and to identify the risk factors.

Methods

Eighty-two consecutive patients with cervical myelopathy who underwent open-door laminoplasty without plates or spacers in the open side (Hirabayashi's original method) were included (62 men and 20 women with a mean age of 62 years and a mean follow-up of 1.8 years). In 67 patients the cause of cervical myelopathy was spondylotic myelopathy, and in 15 it was caused by ossification of posterior longitudinal ligament. Radiographic measurements were made of the anteroposterior diameters of the spinal canal and vertebral bodies from C3–6, and the presence of kyphosis were assessed. Lamina closure was defined as ≥ 10% decrease in the canal-to-body ratio at the final follow-up compared with that immediately after surgery at ≥ 1 vertebral level. The impact of lamina closure on neck pain, patient satisfaction, Japanese Orthopaedic Association scores, and recovery rates were also evaluated.

Results

The mean canal-to-body ratio at C3–6 was 0.69–0.72 preoperatively, 1.25–1.28 immediately after surgery, and 1.18–1.24 at the final follow-up examination. Lamina closure was observed in 34% of patients and was not associated with sex, age, or cause of myelopathy, but was significantly associated with the presence of preoperative kyphosis (p = 0.014). Between patients with and without lamina closure, there was no significant difference in preoperative (9.7 ± 3.1 vs 10.6 ± 2.5) and postoperative (13.7 ± 2.4 vs 13.1 ± 2.7) Japanese Orthopaedic Association scores, recovery rates (53.9 ± 29.9% vs 44.3 ± 29.5%), neck pain scores (3.5 ± 0.7 vs 3.3 ± 1.0), or patient satisfaction level (4.0 ± 1.4 vs 4.8 ± 1.0).

Conclusions

Lamina closure at ≥ 1 vertebral level occurred in 34% of patients. Although patients with lamina closure obtained equivalent recovery from myelopathy in a short-term follow-up, they tended to be less satisfied with surgery compared with those who did not have closure. The only significant risk factor identified was the presence of preoperative cervical kyphosis, and preventative methods for lamina closure, therefore, should be considered for patients with preoperative kyphosis.

A review of prognostic factors for surgical outcome of ossification of the posterior longitudinal ligament of cervical spine

For patients with ossification of the posterior longitudinal ligament (OPLL) who have neurological-symptoms, surgery is necessary but not always effective. Various clinical factors influence the surgical outcome. The studies identifying these factors have been inconclusive and conflicting. It is essential for surgeons to understand the significance of the factors and choose the optimal therapeutic strategy for OPLL. The objective of this review is to determine the clinical factors predictive of the surgical outcome of cervical OPLL. The authors conducted a review of literature published in the English language. They examined studies in which the correlation between clinical factors and outcome were statistically evaluated. The results showed that the traverse area of the spinal cord, the spinal cord-evoked potentials (SCEPs), the increase of the range of motion in the cervical spine (ROM), diabetes, history of trauma, the onset of ossification of the ligament flavum (OLF) in the thoracic spine, snake-eye appearance (SEA) and incomplete decompression may be predictive factors. Age at surgery seems to be closely related to the outcome of posterior surgical procedure. Whether the neurological score, OPLL type, pre-operative duration of symptoms, focal intra-medullar high signal intensity in T2-weighted (IMHSI) and progression of OPLL or kyphosis and expansion of the spinal canal predict the surgical outcome remains unclear. The use of uniform neurological score and proper statistic analysis should facilitate comparison of data from different studies. It is important to analyze the effect of each factor on groups with different surgical procedures as well as patients with different compressive pathology. Research on the etiology and pathology of cervical myelopathy due to OPLL should be helpful in precisely understanding these clinical factors and predicting surgical outcome.

Atypical cervical spondylotic myelopathy mimicking intramedullary tumor

STUDY DESIGN

Case report and a review of the literature.

OBJECTIVE

We report the case of a young man with a short course of progressive cervical myelopathy (CM). Cervical magnetic resonance imaging (MRI) revealed a stenosis of the cervical spinal canal at C4-C6 and an atypically enlarged intramedullary high intensity extending from C1-T1 (T2-weighted) with contrast enhancement at C4-C5 (T1-weighted). Neurologic and radiologic diagnosis therefore favored a tumor of the spinal cord.

SUMMARY OF BACKGROUND DATA

CM is a clinical diagnosis of mostly degenerative origin in older patients that features circumscribed high-intensity signals near the point of compression in T2-weighted MRI. Contrast enhancement in those high-intense areas is rarely described in the literature, and the differentiation from neoplastic and infective lesions might be very difficult in these cases.

METHODS

Retrospective case study with follow-up examination and MRI-control 3 months after surgery.

RESULTS

The patient was decompressed and stabilized from dorsally, and a biopsy was taken. The exact diagnosis of a myelopathy and an exclusion of a neoplastic origin succeeded through histopathological examination. Three months after first surgery, the patient had improved significantly and underwent an additional anterior stabilization, while the MRI remained almost unchanged.

CONCLUSION

In case of a fast progressive CM with atypical radiographic appearance initial decompression with inspection of the spinal cord and a short-term clinical follow-up with an MRI control might be the procedure of choice, if a clear diagnosis for a causative treatment cannot be made. In still suspicious cases, a biopsy could be considered to exclude a neoplastic or inflammatory process.

Cervical spondylosis: ventral or dorsal surgery

Cervical spondylosis is a result of degenerative changes of the cervical spine. Neurological symptoms of myelopathy result from the narrowing of the spinal canal, causing spinal cord compression. Surgical management of cervical stenosis requires an understanding of the interplay between multiple pathological and biomechanical factors contributing to this disease process. Surgical decompression can be addressed from a ventral, dorsal, or combined approach. The authors discuss the technical aspects of the surgical decision making process regarding the decision to approach the spine from a ventral or dorsal orientation.

An analysis of factors causing poor surgical outcome in patients with cervical myelopathy due to ossification of the posterior longitudinal ligament: anterior decompression with spinal fusion versus laminoplasty

OBJECTIVE

We compared the surgical outcome of anterior decompression with spinal fusion (ASF) with the surgical outcome of laminoplasty for patients with cervical myelopathy due to ossification of the posterior longitudinal ligament.

METHODS

The study group comprised 19 ASF patients (A-group) and 40 laminoplasty patients (P-group) treated from 1993 to 2002 with 1 year or longer follow-up. The Japanese Orthopedic Association scoring system was used to evaluate cervical myelopathy, and the recovery rate calculated 1 year after surgery.

RESULTS

The mean recovery rate was 68.4% in the A-group and 52.5% in the P-group (P<0.05). Fifteen patients had a recovery rate less than 40%: 2 in the A-group and 13 in the P-group. One P-group patient and none of the A-group patients developed postoperative aggravation of their neurologic status. The P-group was divided into 2 subgroups: a good outcome group comprising patients whose recovery rate was 40% or higher (n=27) and a poor outcome group comprising patients whose recovery rate was less than 40% (n=13). The mean age at surgery was 59.9 years in the good outcome group and 68.0 years in the poor outcome group (P<0.05). The mean range of intervertebral mobility at maximum cord compression level before surgery was 6.9 degrees in the good outcome group and 10 degrees in the poor outcome group (P<0.05).

CONCLUSIONS

These results demonstrated that the surgical outcome of ASF was superior to the surgical outcome of laminoplasty. Elderly patients treated with laminoplasty showed an especially poor surgical outcome. We suggest that hypermobility of vertebrae at the cord compression level is a risk factor for poor surgical outcome after laminoplasty. Based on these results, we recommend that ASF should be the first choice of treatment for patients with significant ossification of the posterior longitudinal ligament and a hypermobile cervical spine. When laminoplasty is used for such cases, the addition of posterior instrumented fusion would be desirable for stabilizing the spine and decreasing damage to the spinal cord.

Importance of preserving the C7 spinous process and attached nuchal ligament in French-door laminoplasty to reduce postoperative axial symptoms

A comparative clinical trial was conducted to clarify the importance of preserving the C7 spinous process and attached nuchal ligament for the reduction of the axial symptoms after French-door laminoplasty in cervical spondylotic myelopathy patients. Forty-one cervical spondylotic myelopathy patients were enrolled. French-door laminoplasty from C3 to C7 in 22 patients (group 1), and from C3 to C6 in 19 patients (group 2) was performed. The whole structure of the C7 spinous process and the attached nuchal ligament were preserved in group 2. The pre- and post-operative evaluation regarding severity of clinical symptoms was assessed using the Japanese Orthopaedic Association (JOA) score. Pre-operative and subjective outcome regarding axial symptoms were also assessed using a visual analog pain scale questionnaire (VAS: 10-0, where a higher score indicates greater pain) at 1- and 2-year follow-up. Non-parametric testing (Mann-Whitney's U test) was used to establish differences between the two groups for categorical data (P < 0.05). There was no significant difference between the two groups in pre- and post-operative JOA score. The mean VAS was 5.6 +/- 1.4 in group 1, 5.4 +/- 1.7 in group 2 pre-operatively, and 6.4 +/- 1.7 in group 1 and 2.4 +/- 1.9 in group 2 at 1-year follow-up. The mean VAS score at 2-year follow-up exhibited 6.2 +/- 1.9 in Group 1, 2.3 +/- 1.8 in group 2. There was no significant difference in VAS between the two groups before surgery (P = 0.506), but significant differences were noticed at 1-year and 2-year follow-up (P < 0.05), indicating the presence of significantly fewer post-operative axial symptoms in group 2. Laminoplasty of the entire C7 structure is not necessary to obtain satisfactory recovery based on JOA score. Preservation of the C7 spinous process and the attached nuchal ligamentous structures is important to reduce post-laminoplasty axial symptoms.

Long-term results of expansive open-door laminoplasty for cervical myelopathy--average 14-year follow-up study

STUDY DESIGN

Retrospective case series on long-term follow-up results of original expansive open-door laminoplasty for cervical myelopathy due to cervical spondylosis (CSM) and ossification of posterior longitudinal ligament (OPLL).

OBJECTIVES

To elucidate efficacy and problems of original open-door laminoplasty to improve future surgical outcomes.

SUMMARY OF BACKGROUND DATA

Little information is available on long-term outcomes of original open-door laminoplasty without grafts, implants, or instruments.

METHOD

The study group included 80 patients who underwent original open-door laminoplasty and were followed for minimum 10 years. Clinical results, including Japanese Orthopedic Association scores, recovery rates, occurrences of complications, and long-term deterioration were investigated. Cervical alignments, type of OPLL, cervical range of motion, anteroposterior diameter of spinal canal, and progression of OPLL were assessed on plain radiographs. Spinal cord decompression was verified on magnetic resonance imaging.

RESULTS

Average Japanese Orthopedic Association score and recovery rate improved significantly until 3 years after surgery and remained at an acceptable level in both cervical spondylosis and OPLL patients with slight deterioration after 5 years. Segmental motor palsy developed in 8 patients. Late deterioration, mainly lower extremity motor score decline, developed in 8 CSM and 16 OPLL patients. Overall cervical range of motion decreased by 36%. Patients with cervical lordosis decreased gradually in both patient groups. Such changes in alignments did not affect surgical results in CSM patients, while OPLL patients with preoperative kyphosis had lower recovery rates than those with straight and lordotic alignments. OPLL progression that was detected in 66% of patients did not affect clinical results. Although infrequent, magnetic resonance imaging revealed atrophy of spinal cord, spinal cord compression at adjacent segments due to degenerative changes and OPLL progression.

CONCLUSIONS

Long-term results of open-door laminoplasty without bone graft, graft substitutes, or instruments were satisfactory. However, segmental motor paralysis, kyphosis, established before and after surgery, OPLL progression, and late deterioration due to age-related degeneration remain challenging problems.

Cervical laminoplasty

Laminoplasty was developed to treat multilevel pathology of the cervical spine, namely ossification of the posterior longitudinal ligament and cervical spondylotic myelopathy. Laminoplasty was popularized in the 1980s, and since then many variations on the theme have been developed. All are similar in that they expand the cervical canal while leaving the protective dorsal elements in place. Advocates claim that this prevents the formation of the "postlaminectomy" membrane, maintains spinal alignment, and should aid in maintaining cervical range of motion. The aforementioned are all potential shortcomings of laminectomy or laminectomy and fusion. The procedure has proven to be essentially equal to other cervical decompressive procedures in the neutral or lordotic spine, and outcome has been shown to be durable.

Kinetic analysis of the cervical spinal cord in patients after spinous process-splitting laminoplasty using a kinematic magnetic resonance imaging technique

STUDY DESIGN

An in vivo flexion-extension magnetic resonance imaging study.

OBJECTIVE

To evaluate the kinetic changes of the cervical spinal cord after laminoplasty in patients with cervical myelopathy.

SUMMARY OF BACKGROUND DATA

Laminoplasty for cervical myelopathy increases the space occupied by the spinal cord, leading to a decompressive effect on the cord. However, there are few reports on kinetic changes of the spinal cord following this surgical procedure, by which it may contribute to an improvement of clinical symptoms.

METHODS

Patients who underwent spinous process-splitting laminoplasty (n = 40) and control group (n = 20) were enrolled in the study. Cervical spines of the subjects were examined from maximum extension to maximum flexion using a magnetic resonance imaging scanner. Sagittal T1-weighted images were obtained at 12 different angle positions. Images were analyzed with respect to the distance and alignment disparity between the dorsal edge of the vertebral column and the center of the cord at each disc level using National Institutes of Health Image software.

RESULTS

Spinal cords of patients after laminoplasty were dorsally shifted in the enlarged spinal canal at neutral, extension, and flexion positions. Alignment changes of the cord during flexion-extension movements of the cervical spine were dissociated from those of the vertebral column because of smaller changes in the cord alignment.

CONCLUSIONS

Spinous process-splitting laminoplasty increases the degree of freedom of the spinal cord.