Cervical Myelopathy Due to OPLL

Foramen Facet Spinal Classification for Ossification of the Posterior Longitudinal Ligament on Computed Tomography: Closely Related to Clinical Efficacy

STUDY DESIGN

Retrospective study.

OBJECTIVE

To develop and validate computed tomography (CT)-based classification schemes to eliminate ambiguity as much as possible and evaluate the adequacy and clinical value of its classification.

BACKGROUND

There is no objective criteria for laminoplasty of more than one million Chinese patients with ossification of the posterior longitudinal ligament (OPLL) every year. CT imaging can accurately show the location, size, and shape of ossification, it is very important to propose a recognized simple classification of ossifications.

PATIENTS AND METHODS

From 2016 to 2018, 100 patients with "moderate to severe" OPLL on CT were performed according to the following criteria. This study simply classifies the grade of the ossification as 1-2-3, the zone is A-B by the foramen facet spinal canal classification, and the interexaminer reliability is 96%. A prospective series of 60 patients for laminoplasty was performed between 2018 and 2019, and this classification scheme was verified according to the new standard. All patients with size 1 were selectively excluded from consideration for surgery. The Japanese Orthopedic Association scores from both series are superior to most published results for patients with OPLL.

RESULTS

The first and second series reported good to excellent results of 89% and 93.3%, respectively, and 80% and 85% for 24 months. The difference in the incidence of C5 paralysis and axial pain was statistically significant among the different zones, and most of them recovered within 6 months. The most common size and location types are 2-AB, 3-AB, and 2A. The most severe type is 3-AB.

CONCLUSIONS

The foramen facet spinal classification of OPLL is a simple and reliable method for objectively evaluating the ossification of patients with OPLL based on CT research.

LEVEL OF EVIDENCE

Level III.

Technical Aspects of Intra-Operative Ultrasound for Spinal Cord Injury and Myelopathy: A Practical Review

OBJECTIVES

To compile intra-operative techniques, established imaging parameters, available equipment and software, and clinical applications of intraoperative ultrasound imaging (IOUSI) for spinal cord injury (SCI) and myelopathy.

METHODS

PubMed and Google Scholar were searched for relevant articles. The articles were reviewed and selected by 2 independent researchers. After article selection, data were extracted and summarized into research domains. PRISMA systematic review process was followed.

RESULTS

Of the 2477 articles screened, 16 articles met the inclusion criteria. In patients with SCI and myelopathy, common quantitative measurements obtained using IOUSI were noted: 1) ultrasound elastography, 2) midsagittal anteroposterior diameter, 3) transverse, 4) transverse diameter, 5) maximum spinal cord compression, and 6) compression ratioTo ensure adequate decompression and to look for residual compression, the lateral and the craniocaudal margins of the laminectomy site were inspected in both axial and sagittal planes. In instances where quantitative assessment was not possible, cord decompression and degree of residual compression were gauged by inspecting the interface between the ventral border of the spinal cord and any potentially compressive elements, and by searching for symmetric and rhythmic cerebrospinal fluid pulsations. Use of contrast-enhanced ultrasoundand molecular imaging are additional advances in objective assessments for SCI and myelopathy.

CONCLUSIONS

This review outlines the potential of IOUSI in patients presenting with SCI and myelopathy. Moreover, by identifying potential for inter-operator variability in certain subjective measurements, we illustrate the need for further research to quantify and standardize those assessments.

Systematic Review: Applications of Intraoperative Ultrasound in Spinal Surgery

BACKGROUND

Due to increased practicality and decreased costs and radiation, interest has risen for intraoperative ultrasound (iUS) in spinal surgery applications; however, few studies have provided a robust overview of its use in spinal surgery. We synthesize findings of existing literature on usage of iUS in navigation, pedicle screw placement, and identification of anatomy during spinal interventions.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were utilized in this systematic review. Studies were identified through PubMed, Scopus, and Google Scholar databases using the search string. Abstracts mentioning iUS in spine applications were included. Upon full-text review, exclusion criteria were implemented, including outdated studies or those with weak topic relevance or statistical power. Upon elimination of duplicates, multi-reviewer screening for eligibility, and citation search, 44 manuscripts were analyzed.

RESULTS

Navigation using iUS is safe, effective, and economical. iUS registration accuracy and success is within clinically acceptable limits for image-guided navigation (Table 2). Pedicle screw instrumentation with iUS is precise with a favorable safety profile (Table 2). Anatomical landmarks are reliably identified with iUS, and surgeons are overwhelmingly successful in neural or vascular tissue identification with iUS modalities including standard B mode, doppler, and contrast-enhanced ultrasound (CE-US) (Table 3). iUS use in traumatic reduction of fractures properly identifies anatomical structures, intervertebral disc space, and vasculature (Table 3).

CONCLUSION

iUS eliminates radiation, decreases costs, and provides sufficient accuracy and reliability in identification of anatomical and neurovascular structures in various spinal surgery settings.

Potential of intraoperative ultrasonographic assessment of the spinal cord central echo complex in predicting postoperative neurological recovery of degenerative cervical myelopathy

BACKGROUND AND PURPOSE

The spinal cord central echo complex (SCCEC) is a special ultrasonography-based intramedullary structure, but its clinical significance in degenerative cervical myelopathy (DCM) is undefined. This study aimed to explore the potential of the SCCEC in predicting postoperative neurological recovery in DCM.

METHODS

Thirty-two DCM patients who underwent intraoperative ultrasonography-guided French-door laminoplasty were prospectively enrolled. The modified Japanese Orthopaedic Association (mJOA) score was evaluated preoperatively and 12 months postoperatively. SCCEC width (SCCEC-W), and anteroposterior diameter (APD) and transverse diameter (TD) of the spinal cord were measured on transverse ultrasonographic images, while the tissue widths from anterior and posterior borders of the spinal cord to the SCCEC were measured on sagittal ultrasonographic images. The APD of the spinal cord and occupying rate of the spinal canal were measured on preoperative magnetic resonance imaging (MRI).

RESULTS

All patients achieved improvements in mJOA scores, with an average recovery rate (RR) of 68.69 ± 20.22%. Spearman correlation analysis revealed that SCCEC-W, and ratios between the SCCEC-W and APD/TD based on ultrasonography, correlated moderately with mJOA score RR, with coefficients of -0.527, -0.605 and -0.514, respectively. The ratio between SCCEC-W and ultrasonographic TD correlated moderately with preoperative APD of the spinal cord. The MRI measurements and ultrasonography-based tissue widths showed no significant correlation with mJOA score RR.

CONCLUSIONS

The SCCEC may have predictive potential as an intraoperative indicator of neurological recovery in treating DCM. SCCEC-W may be related to spinal cord compression in DCM.

Consensus statement on diagnosis and treatment of cervical ossification of posterior longitudinal ligament from Asia Pacific Spine Society (APSS) 2020

PURPOSE

The study aimed to develop an evidence-based expert consensus statement on diagnosis and treatment of cervical ossification posterior longitudinal ligament (OPLL).

METHOD

Delphi method was used to perform such survey, and the panel members from Asia Pacific Spine Society (APSS) 2020 were invited to answer the open-ended questions in rounds 1 and 2. Then the results were summarized and developed into a Likert-style questionnaire for voting in round 3, and the level of agreement was defined as 80%. In the whole process, we conducted a systematic literature search on evidence for each statement.

RESULTS

Cervical OPLL can cause various degrees of neurological symptoms, an it's thought to be more common in Asia population. CT reconstruction is an important imaging examination to assist diagnosis and guide surgical choice. Segmental, continuous, mixed, and focal type is the most widely used classification system. The non-surgical treatment is recommended for patients with no or mild clinical symptoms, or irreversible neurological damage, or failed surgical decompression, or condition cannot tolerant surgery, or refusing surgery. As OPLL may continue to develop gradually, surgical treatment would be considered in their course inevitably. The surgical choice should depend on various conditions, such as involved levels, thickness, and type of OPLL, skill-experiences of surgeons, which are listed and discussed in the article.

CONCLUSION

In this statement, we describe the clinical features, classifications, and diagnostic criteria of cervical OPLL, and review various surgical methods (such as their indications, complications), and provide a guideline on their choice strategy.

Modified axial computed tomography classification of cervical ossification of the posterior longitudinal ligament: selecting the optimal operating procedure and enhancing the accuracy of prognosis

Background

Cervical ossification of the posterior longitudinal ligament (OPLL) causes spinal cord compression, which can lead to myelopathy or radiculopathy. Non-surgical treatments have little effect on this condition. Current OPLL classification systems offer little guidance on the selection of an appropriate operating procedure. In this study, we developed a modified axial computed tomography classification (MACTC) scheme. We then examined the usefulness of the MACTC scheme and two other existing classification schemes in guiding OPLL operation choice.

Methods

Following screening in which a defined exclusion criteria was used, a total of 91 patients with OPLL participated in the study. Patients' follow-up data for at least 2 years were obtained. The recovery rate of the Japanese Orthopaedic Association (JOA) scores was compared to two other classification schemes.

Results

According to the MACTC, central-sharp-type OPLL had a lower recovery rate of the JOA score than that of central-gentle-type OPLL (36.05±32.38 vs. 83.90±23.52, P≤0.05). The recovery rate of the JOA scores in the ipsilateral open-door OPLL group was significantly lower than that in the contralateral group of the lateral-steep type (36.67±41.5 vs. 88.89±17.21, P=0.04), but not of that in the lateral-gentle type. There was no significant difference in the recovery rates of the JOA scores between groups when using either existing classification scheme (P>0.05).

Conclusions

The MACTC scheme can assist surgeons to choose the most appropriate operating procedure, and provide an accurate prognosis. If operations on central-sharp-type OPLL are not performed using both the posterior and anterior approaches, prognosis will be poor. The contralateral side should be the first choice for door opening in laminoplasty, especially for patients with lateral-steep-type OPLL. Severe OPLL may not be an absolute contraindication for the posterior approach.

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.

Increased signal intensity of spinal cord on T2W magnetic resonance imaging for cervical spondylotic myelopathy patients: Risk factors and prognosis (a STROBE-compliant article)

To investigate the risk factors for progression of increased signal intensity (ISI) on T2W magnetic resonance imaging (MRI) and its prognostic value in patients with cervical spondylotic myelopathy (CSM).A total of 109 patients with CSM were included in this study. All the patients were treated with anterior cervical discectomy and fusion. MRI was performed for all 109 patients preoperatively and at the final follow-up. Radiological evaluation included ISI, anterior compression (AC) of dural and spinal cord, hyperintensity region (HR) at the involved level. Clinical data including Japanese Orthopedic Association (JOA) score, Neck Disability Index (NDI) score, and Visual Analogue Scale were collected and evaluated. Patients were divided into 2 groups according to ISI grades (Group A: no hyper-intensity; Group B: presence of ISI). Then all patients presented with ISI were divided into 2 subgroups based on the range of HR (Group B1: hyper-intensity diameter accounts for less than half of the spinal cord diameter at the involved level; Group B2, hyper-intensity diameter accounts for more than half of the spinal cord diameter at the involved level). AC, disease duration, age, and gender were analyzed as potential risk factors.Significantly better JOA and NDI scores were observed in Group A preoperatively and at the final follow-up, compared to Group B (P < .05). Disease duration was found significantly longer in patients with ISI (P < .05). Notably better JOA and NDI scores were noticed in Group B1 rather than Group B2 (P < .05). Logistical regression showed that disease duration was the only factor that significantly correlated with the progress of ISI (P < .001).CSM patients with ISI on T2W MR images had poorer surgical outcomes compared to others, while the increased range of HR may deteriorate preoperative neurological function. Moreover, patients with longer disease duration had greater risk of ISI in spinal cord.

Short-term predictive potential of quantitative assessment of spinal cord impairment in patients undergoing French-door Laminoplasty for degenerative cervical myelopathy: preliminary results of an exploratory study exploiting intraoperative ultrasound data

BACKGROUND

To study the correlation of neurological function in degenerative cervical myelopathy (DCM) patients with quantitative assessment of spinal cord compression and impairment by intraoperative ultrasound imaging (IOUSI).

METHODS

Twenty-three patients who underwent French-Door laminoplasty for multilevel DCM were followed for 6 months. Modified Japanese Orthopaedic Association (mJOA) score and cervical MRI were assessed before surgery and at postoperative 6 months. IOUS, used to guide decompression, were recorded. The anteroposterior diameter (APD) and the gray values of the IOUSI hyperechogenicity of the midsagittal IOUSI at the narrowest level and at the lesion-free level, and the APD and traverse diameter at the traverse maximum compression level of IOUSI were measured. Maximum spinal cord compression (MSCC), compression rate (CR), and IOUSI gray value ratio (R_gray) were calculated. The appearance of preoperative T2W MRI increased signal intensity (ISI), and the signal change rate (SCR) on postoperative T2W MRI of 9 patients were also measured and calculated, and compared with that of IOUSI hyperechogenicity.

RESULTS

Average mJOA score increased significantly from 11.57 ± 2.67 before surgery to 15.39 ± 1.50 at 6 months after surgery, with an average recovery rate (RR) of 71.11 ± 22.81%. The difference between the appearance of preoperative T2W MRI ISI and IOUSI hyperechogenicity was not significant. Spearman correlation analysis found that the IOUSI R_gray were negatively correlated with the RR of mJOA score with a coefficient of - 0.77, and the IOUSI R_gray was not correlated with the postoperative MRI SCR.

CONCLUSIONS

In DCM patients, the gray values of IOUSI can be measured accurately. The IOUSI R_gray correlated with postoperative neurological recovery significantly.

Review of Radiological Parameters, Imaging Characteristics, and Their Effect on Optimal Treatment Approaches and Surgical Outcomes for Cervical Ossification of the Posterior Longitudinal Ligament

Determining the optimal surgical method for cervical ossification of the posterior longitudinal ligament (OPLL) is challenging. The surgical indication should be made based on not only radiological findings, but also the patient’s age, preoperative neurological findings, social background, activities of daily life, and the presence or absence of comorbid diseases. Anterior resection for OPLL with or without wide corpectomy and fusion, posterior decompression with or without relatively long fusion, or anterior and posterior combined surgery may be considered. When evaluating the clinical condition of patients with cervical OPLL before surgery, various radiological parameters should be carefully considered, including the number of spinal segments involved, the cervical alignment or tilt angle, the relationship between OPLL and the C2–7 line (termed the “K-line”), the occupying ratio of OPLL, and the involvement of dural ossification. The objective of this article is to review the radiological parameters in current use for deciding upon the optimal surgical strategy and for predicting surgical outcomes, focusing on cervical OPLL.

Outcome Measures and Variables Affecting Prognosis of Cervical Spondylotic Myelopathy: WFNS Spine Committee Recommendations

This study is conducted to review the literature systematically to determine most reliable outcome measures, important clinical and radiological variables affecting the prognosis in cervical spondylotic myelopathy patients. A literature search was performed for articles published during the last 10 years. As functional outcome measures we recommend to use modified Japanese Orthopaedic Association scale, Nurick’s grade, and Myelopathy Disability Index. Three clinical variables that affect the outcomes are age, duration of symptoms, and severity of the myelopathy. Examination findings require more detailed study to validate their effect on the outcomes. The predictive variables affecting the outcomes are hand atrophy, leg spasticity, clonus, and Babinski’s sign. Among the radiological variables, the curvature of the cervical spine is the most important predictor of prognosis. Patients with instability are expected to have a poor surgical outcome. Spinal cord compression ratio is a critical factor for prognosis. High signal intensity on T2-weighted magnetic resonance images is a negative predictor for prognosis. The most important predictors of outcome are preoperative severity and duration of symptoms. T2 hyperintensity and cord compression ratio can also predict outcomes. New radiological tests may give promising results in the future.

A Systematic Review of Classification Systems for Cervical Ossification of the Posterior Longitudinal Ligament

DESIGN

Systematic review.

OBJECTIVE

To conduct a systematic review to (1) summarize various classification systems used to describe cervical ossification of the posterior longitudinal ligament (OPLL) and (2) evaluate the diagnostic accuracy of various imaging modalities and the reliability of these classification systems.

METHODS

A search was performed to identify studies that used a classification system to categorize patients with OPLL. Furthermore, studies were included if they reported the diagnostic accuracy of various imaging modalities or the reliability of a classification system.

RESULTS

A total of 167 studies were deemed relevant. Five classification systems were developed based on X-ray: the 9-classification system (0.60%); continuous, segmental, mixed, localized or focal, circumscribed and others (92.81%); hook, staple, bridge, and total types (2.40%); distribution of OPLL (2.40%); and K-line classification (4.19%). Six methods were based on computed tomography scans: free-type, contiguous-type, and broken sign (0.60%); hill-, plateau-, square-, mushroom-, irregular-, or round-shaped (5.99%); rectangular, oval, triangular, or pedunculate (1.20%); centralized or laterally deviated (1.80%); plank-, spindle-, or rod-shaped (0.60%); and rule of nine (0.60%). Classification systems based on 3-dimensional computed tomography were bridging and nonbridging (1.20%) and flat, irregular, and localized (0.60%). A single classification system was based on magnetic resonance imaging: triangular, teardrop, or boomerang. Finally, a variation of methods was used to classify OPLL associated with the dura mater (4.19%).

CONCLUSIONS

The most common method of classification was that proposed by the Japanese Ministry of Health, Labour and Welfare. Other important methods include K-line (+/-), signs of dural ossification, and patterns of distribution.

Ossification of the posterior longitudinal ligament in the cervical spine: a review

Ossification of the posterior longitudinal ligament (OPLL) is a rare pathologic process of lamellar bone deposition that can result in spinal cord compression. While multiple genetic and environmental factors have been related to the development of OPLL, the pathophysiology remains poorly understood. Asymptomatic patients may be managed conservatively and patients with radiculopathy or myelopathy should be considered for surgical decompression. Multiple studies have demonstrated the morphology and size of the OPLL as well as the cervical alignment have significant implications for the appropriate surgical approach and technique. In this review, we aim to address all the available literature on the etiology, history, presentation, and management of OPLL in an effort to better understand OPLL and give our recommendations for the treatment of patients presenting with OPLL.

High cord signals on magnetic resonance and other factors predict poor outcomes of cervical spine surgery: A review

Background:

High cord signals (HCS) on preoperative/postoperative T1, T1 gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), and T2 magnetic resonance (MR) studies, postoperative failure of HCS to regress and/or cord re-expansion, and a triangular cord configuration are poor prognostic factors for surgical patients with cervical spondylotic myelopathy (CSM).

Methods:

Here, we reviewed the negative prognostic import of high Grades/Types and more extensive locations of preoperative/postoperative HCS on T1, T1 Gd-DTPA, and T2 MR studies in surgical patients with CSM. Additional predictors of poor operative outcomes included postoperative failure of HCS to regress, cord re-expansion at the site of a HCS, and the triangular vs. teardrop or boomerang cord configuration. The Types/Grades of HCS on MR follow:Type/Grade 0 – no/absent signal changes; Type/Grade 1 – mild/light/fuzzy/obscure/low cord signal (LCS) changes; Type/Grade 2 – sharp/intense/well-defined HCS; and Type/Grade 3 – mixed/HCS. The definitions of location/extent of LCS/HCS were: focal (1 level), multifocal (with skip areas), and multisegmental (continuous over >1 segment), while cord configuration was categorized as triangular, teardrop, or boomerang.

Results:

On MR studies, preoperative/postoperative Types/Grades 0–1 changes correlated with better prognoses (e.g., improved Japanese Orthopedic Association (JOA) scores or Nurick Grades), while Types/Grades 2–3 correlated with poorer outcomes. Multiple poor prognostic indicators also included; failure of postoperative HCS on MR to regress (particularly if multisegmental), postoperative cord re-expansion at the site of a prior HCS, and triangular cord configuration.

Conclusions:

Grade/Types 2–3 HCS on T1, T1 Gd-DTPA, and T2-weighted MR images on preoperative/postoperative MR studies, failure of HCS to regress (multisegmental), cord re-expansion at the site of a prior HCS, and a triangular cord configuration (atrophy) all contributed to poorer outcomes for CSM surgery.

Use of Intraoperative Ultrasound During Spinal Surgery

STUDY DESIGN

Review and technical report.

OBJECTIVE

Intraoperative ultrasound has been used by spine surgeons since the early 1980s. Since that time, more advanced modes of intraoperative imaging and navigation have become widely available. Although the use of ultrasound during spine surgery has fallen out of favor, it remains the only true real-time imaging modality that allows surgeons to visualize soft tissue anatomy instantly and continuously while operating. It is our objective to demonstrate that for this reason, ultrasound is a useful adjunctive technique for spine surgeons, especially when approaching intradural lesions or when addressing pathology in the ventral spinal canal via a posterior approach.

METHODS

Using PubMed, the existing literature regarding the use of intraoperative ultrasound during spinal surgery was evaluated. Also, surgical case logs were reviewed to identify spinal operations during which intraoperative ultrasound was used. Illustrative cases were selected and reviewed in detail.

RESULTS

This article provides a brief review of the history of intraoperative ultrasound in spine surgery and describes certain surgical scenarios during which this technique might be useful. Several illustrative cases are provided from our own experience.

CONCLUSIONS

Surgeons should consider the use of intraoperative ultrasound when approaching intradural lesions or when addressing pathology ventral to the thecal sac via a posterior approach.

Ossification of the Posterior Longitudinal Ligament: Imaging Findings in the Era of Cross-Sectional Imaging

Imaging appearance and classification systems of ossification of the posterior longitudinal ligament (OPLL) on computed tomography and magnetic resonance imaging will be reviewed. Computed tomography evaluation most accurately demonstrates OPLL length and thickness, whereas magnetic resonance imaging has the advantage of demonstrating abnormal signal in the cord. Neurologic symptoms are most common in the cervical spine and are related to the degree of spinal stenosis and presence of cord edema. Surgical treatment usually involves cases of cervical OPLL and includes anterior or posterior decompression.

Preoperative magnetic resonance imaging is associated with baseline neurological status and can predict postoperative recovery in patients with cervical spondylotic myelopathy

STUDY DESIGN

A blinded observational study of consecutive patients, prospectively enrolled and followed up to 1 year postoperatively.

OBJECTIVE

To assess whether quantitative assessment of preoperative magnetic resonance imaging (MRI) predicts baseline patient status and postoperative neurological recovery.

SUMMARY OF BACKGROUND DATA

Factors that can predict neurological recovery in patients with cervical spondylotic myelopathy (CSM) postoperatively are of great interest. Currently, the literature regarding the significance of MRI signal changes in relation to prognosis is inconsistent and conflicting.

METHODS

A total of 57 consecutive patients with CSM were studied preoperatively and 1 year postoperatively. Modified Japanese Orthopaedic Association (mJOA), Nurick Grade, SF-36, neck disability index, 30-meter walk cadence (Wc) and time (Wt), grip strength, and Berg Balance Scale were administered at baseline and 1 year after surgery. Preoperative status and postoperative recovery were assessed in relation to quantitative MRI measurements pre- and postoperatively using univariate and multivariate analysis.

RESULTS

Low T1 signal change preoperatively was associated with a lower mJOA (P = 0.0030), higher Nurick Grade (P = 0.0298), decreased grip (P = 0.0152), impaired Wt, Wc (P≤ 0.0001) and poor Berg Balance Scale (P = 0.0005) at baseline. Focal high T2 signal was associated with lower mJOA scores and higher Nurick Grade compared with diffuse T2 (P = 0.0035 P = 0.0079) or no T2 signal (P = 0.0680 P = 0.0122). Preoperative segmentation of T2 signal, showed a significant increase in Wt, Wc, and Berg Balance Scale (P = 0.0266; P = 0.0167; P = 0.0042). Preoperative T1 signal was associated with lower postoperative grip (P = 0.0260), greater Wt, Wc (P = 0.0360, P = 0.0090). Preoperative focal T2 signal had a significant association with poorer postoperative Wt, Wc (P = 0.0220) and Nurick Grade (P = 0.0230). Preoperative maximal cord compromise was negatively correlated with postoperative SF-36 mental score (P = 0.0130).

CONCLUSION

MRI signal changes are predictive of baseline neurological status and postoperative recovery. MRI indicators of poorer outcome include the presence of low T1 signal, focal increased T2 signal and segmentation of T2 signal changes.

LEVEL OF EVIDENCE

2.

Qualitative evidence from a systematic review of prognostic predictors for surgical outcomes following cervical ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) is a pathological ectopic ossification of this ligament that usually occurs in the cervical spine. For patients with cervical OPLL and neurological symptoms, surgical intervention is necessary but not always effective. Various prognostic factors influence the surgical outcome. The results of studies identifying these prognostic predictors are often inconclusive or contradictory. These predictors have not been well identified or summarized. The present study was designed to identify the prognostic predictors for the surgical outcome of cervical OPLL based on the available evidence in the literature. Non-interventional studies were searched in Medline, Embase, Science Direct, OVID and the Cochrane library. Forty-two observational studies involving 2791 patients were included. The quality of the included studies was assessed with a modified quality assessment tool, which was originally designed for use with observational studies. The effects of the studies were combined with the study quality score using a model of best-evidence synthesis. There was strong evidence for five predictors: (i) age, (ii) duration of symptoms, (iii) pre-operative neurological score, (iv) transverse area of the spinal cord, and (v) intramedullary high signal intensity on the T2-weighted MRI. We also identified eight predictors with moderate supporting evidence, seven with limited evidence, four with conflicting evidence and four predictors without supporting evidence. While there is no conclusive evidence regarding the surgical outcomes following cervical OPLL, these data provide evidence to guide the clinician in choosing an optimal therapeutic strategy for patients with cervical OPLL. Further research is necessary to fully evaluate the effects of the predictors described in this study.

In vivo tracing of neural tracts in tiptoe walking Yoshimura mice by diffusion tensor tractography

STUDY DESIGN

Basic imaging experiment.

OBJECTIVE

To determine whether in vivo diffusion tensor tractography (DTT) can be used to evaluate the axonal disruption of the chronically compressed spinal cord in tiptoe walking Yoshimura (twy) mice.

SUMMARY OF BACKGROUND DATA

In cervical ossification of the posterior longitudinal ligament, axonal disruption results in motor and sensory functional impairment. Twy mice develop spontaneous calcification in the cervical ligaments, which causes chronic compression of the spinal cord. DTT is emerging as a powerful tool for tracing axonal fibers in vivo.

METHODS

Five twy mice were subjected to DTT at 6, 15, and 20 weeks of age. Magnetic resonance imaging was performed using a 7.0-Tesla magnet (Biospec 70/16; Billerica, MA) with a CryoProbe. Diffusion tensor images were analyzed using TrackVis (Massachusetts General Hospital, MA). Motor performance was evaluated by Rotarod treadmill test and Digigait analysis. Histological analysis was performed by hematoxylin-eosin staining and immunostaining for RT-97 and SMI-31.

RESULTS

High resolution DTT of twy mice in vivo was successful. A lower number of RT-97- or SMI-31-positive fibers were associated with more severe spinal cord compression, which was determined by observing the ligamentous calcification at the C2-C3 level in each twy mouse. The severity of canal stenosis based on magnetic resonance images was strongly correlated with the axial area of the spinal cord. The tract fiber (TF) ratio (the number of TFs at the C2-C3 level/the number of TFs at the C0-C1 level) was strongly correlated with the RT-97/SMI-31-positive area and with motor function (rotarod latency, stride length). Furthermore, a two-part linear regression analysis showed that canal stenosis around 50% to 60% caused a sharp decrease in the TF ratio before the deterioration of motor function.

CONCLUSION

We conclude that DTT could be useful for detecting the early changes associated with the compressed spinal cord in cervical ossification of the posterior longitudinal ligament.

Gross morphological changes of the spinal cord immediately after surgical decompression in a large animal model of traumatic spinal cord injury

STUDY DESIGN

Quantitative in vivo ultrasound imaging study of spinal cord and dura morphology after acute experimental spinal cord injury (SCI) and decompression in a pig model.

OBJECTIVE

To study the morphological changes of the spinal cord and dura immediately after surgical decompression for acute SCI.

SUMMARY OF BACKGROUND DATA

Surgical decompression for traumatic SCI is currently a topic of debate. After decompression, relief of bony impingement on the thecal sac and spinal cord can be confirmed intraoperatively. However, postoperative imaging often reveals that the cord has swollen to fill the subarachnoid space. Little is known about the extent and timing of this morphological response.

METHODS

Yucatan miniature pigs received sham surgery (N = 1) or a moderate (N = 6, 20 g, 2.3 m/s) or high (N = 6, 20 g, 4.7 m/s) severity weight-drop SCI followed by 8 hours of sustained compression (100 g) and 6 hours of postdecompression monitoring. Sagittal-plane ultrasound images were used to quantify spinal cord, dura, and subarachnoid space dimensions preinjury and once per hour after decompression.

RESULTS

Animals with a moderate SCI exhibited a residual cord deformation of up to 0.64 mm within 10 minutes of decompression, which tended to resolve during 6 hours because of tissue relaxation and swelling. For animals with high-severity SCIs, cord swelling was immediate and resulted in occlusion of the subarachnoid space within 10 minutes to 5 hours, whereas this occurred for only half of the moderate injury group.

CONCLUSION

Decompression of an acute SCI may result in residual cord deformation followed by gradual swelling or immediate swelling leading to subarachnoid occlusion. The response is dependent on initial injury severity. These observations may partly explain the lack of benefit of decompression in some patients and suggest a need to reduce cord swelling to optimize the clinical outcome after acute SCI.

Postoperative magnetic resonance imaging can predict neurological recovery after surgery for cervical spondylotic myelopathy: a prospective study with blinded assessments

BACKGROUND

Factors that can predict the recovery of cervical spondylotic myelopathy (CSM) patients postoperatively are of significant interest to physicians and patients and their families. Magnetic resonance imaging (MRI) scans are a common method of examination after surgery, and thus of interest as a predictor of outcome.

OBJECTIVE

To investigate whether findings on MRI at 6 months postoperatively could predict recovery at 1 year in CSM patients.

METHODS

In 52 consecutive prospective patients, MRI was performed preoperatively and 6 months postoperatively. T1 and T2 signal change (area, height, and segmentation) and spinal cord re-expansion were measured. Outcome measures evaluated at 1 year postoperatively were compared with preoperative values. Univariate and stepwise multiple regressions were undertaken.

RESULTS

Using univariate analysis, patients whose cord failed to re-expand had poorer outcome according to the modified Japanese Orthopedic Association score and Nurick score (P = .014) and grip test (P = .006) postoperatively. Stepwise multivariate regression showed lack of cord re-expansion to be predictive of prognosis postoperatively in the modified Japanese Orthopedic Association score (P = .013) and Berg Balance Scale (P = .014), and walking test (P = .011). Postoperative hyperintense T2 signal change was predictive of worse outcome on the Berg Balance Scale (P = .014) and walking test (P = .020), Nurick score (P = .001), and Short Form-36 scores (P = .020). In cases in which the T2 signal intensified, there was a poorer outcome on Nurick scores (P = .013), grip test (P = .017), and Short Form-36 scores (P = .030).

CONCLUSION

Findings on postoperative MRI at 6 months is of predictive value in determining outcomes in CSM patients. The persistence and type of T2 signal change and lack of re-expansion of the cord correlate with poorer recovery and likely reflect irreversible structural changes in the spinal cord.

Ossification of the posterior longitudinal ligament: a review of literature

Ossification of the posterior longitudinal ligament (OPLL) is most commonly found in men, in the elderly, and in Asian patients. The disease can start with mild or no symptoms, but some patients progress slowly to develop symptoms of myelopathy. An accurate diagnosis through the use plain radiograph, computed tomography, and magnetic resonance imaging findings is very important to monitor the development of symptoms and to make decisions regarding a treatment plan. When symptoms are mild and non-progressive, conservative treatments and periodic observations are good enough, but once symptoms of myelopathy are present and neurologic symptoms are progressive, the treatment of choice is surgery to relieve spinal cord compression. Surgical management of OPLL continues to be controversial. Each surgical technique has some advantages and disadvantages, and the choice of operation should be decided carefully with various considerations. The patient's neurological condition, location and extent of pathology, cervical kyphosis, presence or absence of accompanied instability, and the individual surgeon's experience must be an important factors that should be considered before surgery.

The value of intraoperative ultrasound in oblique corpectomy for cervical spondylotic myelopathy and ossified posterior longitudinal ligament

Intraoperative ultrasound (IOUS) has been described to be useful during central corpectomy for compressive cervical myelopathy. This study aimed at documenting the utility of IOUS in oblique cervical corpectomy (OCC). Prospective data from 24 patients undergoing OCC for cervical spondylotic myelopathy and ossified posterior longitudinal ligament (OPLL) were collected. Patients had a preoperative cervical spine magnetic resonance (MR) image, IOUS and a postoperative cervical CT scan. Retrospective data from 16 historical controls that underwent OCC without IOUS were analysed to compare the incidence of residual compression between the two groups. IOUS identified the vertebral artery in all cases, detected residual cord compression in six (27%) and missed compression in two cases (9%). In another two cases with OPLL, IOUS was sub-optimal due to shadowing. IOUS measurement of the corpectomy width correlated well with these measurements on the postoperative CT. The extent of cord expansion noted on IOUS after decompression showed no correlation with immediate or 6-month postoperative neurological recovery. No significant difference in residual compression was noted in the retrospective and prospective groups of the study. Craniocaudal spinal cord motion was noted after the completion of the corpectomy. IOUS is an inexpensive and simple real-time imaging modality that may be used during OCC for cervical spondylotic myelopathy. It is helpful in identifying the vertebral artery and determining the trajectory of approach, however, it has limited utility in patients with OPLL due to artifacts from residual ossification.

Ossification of the posterior longitudinal ligament: a review

Ossification of the posterior longitudinal ligament (OPLL) is most commonly found in men, the elderly, and Asian patients. There are many diseases associated with OPLL, such as diffuse idiopathic skeletal hyperostosis, ankylosing spondylitis, and other spondyloarthropathies. Several factors have been reported to be associated with OPLL formation and progression, including genetic, hormonal, environmental, and lifestyle factors. However, the pathogenesis of OPLL is still unclear. Most symptomatic patients with OPLL present with neurological deficits such as myelopathy, radiculopathy, and/or bowel and bladder symptoms. There are some reports of asymptomatic OPLL. Both static and dynamic factors are related to the development of myelopathy. Plain radiography, CT, and MR imaging are used to evaluate OPLL extension and the area of spinal cord compression. Management of OPLL continues to be controversial. Each surgical technique has some advantages and disadvantages, and the choice of operation should be made case by case, depending on the patient's condition, level of pathology, type of OPLL, and the surgeon's experience. In this paper, the authors attempt to review the incidence, pathology, pathogenesis, natural history, clinical presentation, classification, radiological evaluation, and management of OPLL.

Using the T2-weighted magnetic resonance imaging signal intensity ratio and clinical manifestations to assess the prognosis of patients with cervical ossification of the posterior longitudinal ligament

OBJECT

The aim of this study was to investigate the clinical significance of both the signal intensity ratio obtained from MR imaging and clinical manifestations on the prognosis of patients with cervical ossification of the posterior longitudinal ligament.

METHODS

The authors retrospectively reviewed the records of 58 patients with cervical ossification of the posterior longitudinal ligament who underwent cervical laminoplasty from February 1999 to July 2007. Magnetic resonance imaging (1.5-T) was performed in all patients before surgery. Sagittal T2-weighted images of the cervical spinal cord compressed by the ossified posterior longitudinal ligament showed increased intramedullary signal intensity, whereas the sagittal images obtained at the C7-T1 disc levels were of normal intensity. The signal intensity ratio between regions of intramedullary increased signal intensity and the normal C7-T1 disc level was calculated based on the signal intensity values generated from the MR imaging workstation. Patients were divided into 3 groups according to their signal intensity ratio (high, intermediate, and low signal intensity groups).

RESULTS

There were significant differences between the 3 groups regarding recovery rate (p < 0.001), age (p = 0.022), duration of disease (p = 0.001), Babinski sign (p < 0.001), ankle clonus (p < 0.001), and both pre- and postoperative Japanese Orthopaedic Association score (p < 0.001). There was no significant difference in sex among the 3 groups (p = 0.391).

CONCLUSIONS

Patients with low signal intensity ratios that changed on T2-weighted imaging experienced a good surgical outcome. Low increased signal intensity might reflect mild neuropathological alteration in the spinal cord and greater recuperative potential. An increased signal intensity ratio with positive pyramidal signs indicates less recuperative potential of the spinal cord and a poor surgical outcome.

Thoracic myelopathy due to ossification of ligamentum flavum: a retrospective analysis of predictors of surgical outcome and factors affecting preoperative neurological status

Despite good posterior decompression of thoracic myelopathy due to ossification of ligamentum flavum (OLF), recovery varies widely from 25 to 100%. Neurological status on presentation also varies widely in different patients. We, therefore retrospectively studied relation of various clinical and magnetic resonance imaging (MRI) parameters with preoperative neurological status and postoperative recovery in 25 patients who underwent decompressive laminectomy for thoracic myelopathy due to OLF. Patients were assessed using leg-trunk-bladder scores of JOA scale and recovery rate (RR) was calculated as RR = postoperative score - preoperative score/11 - preoperative score × 100. With Pearson's correlation, postoperative recovery rate (RR) significantly correlated with preoperative duration of symptoms, JOA score, sensory JOA score, canal grade, dural canal-body ratio (DCBR), intramedullary signal size (ISS), and intramedullary signal type (IST) on MRI. On MRI, two types of signal changes were identified: normal in T1/hyperintense in T2 representing cord edema and hypointense in T1/hyperintense in T2 representing cystic changes indicating lesser and higher grades, respectively. Presence or absence of signal changes did not correlate with postoperative recovery; but whenever present, ISS greater than 15 mm significantly compromised recovery. Multiple regression analysis (MRA) identified preoperative duration of symptoms and preoperative ISS as significant predictors of postoperative outcome. Based on MRA, we formulated a multiple regression equation to predict RR as Predicted RR = 83.4 + (0.1 × age in years) - (0.7 × preoperative duration of symptoms in months) + (1.5 × preoperative JOA score) + (0.2 × preoperative canal grade in percentage) - (2.5 × ISS in mm) - (1.5 × IST in grade). Though age, preoperative anal sensations, spasticity, canal grade, DCBR, ISS, and IST significantly correlated with preoperative neurological status, MRA identified ISS as most important factor determining preoperative neurological status. Preoperative duration of symptoms and developmentally narrow canal had no influence on preoperative neurological status. Patients with developmentally narrow canal showed significant correlation with younger age at onset of myelopathy. To conclude, only independent factor determining preoperative neurological status is ISS. Predictors of postoperative recovery are preoperative duration of symptoms and ISS. Postoperative recovery can be predicted by formulated equation.

Effect of spinal cord signal intensity changes on clinical outcome after surgery for cervical spondylotic myelopathy

OBJECT

The presence of intramedullary T2 high signal intensity changes in patients with cervical spondylotic myelopathy (CSM) indicates the existence of a chronic spinal cord compressive lesion. However, the prognostic significance of signal intensity changes remains controversial. The purpose of this study was to evaluate the effect of spinal cord T2 signal intensity changes on the outcome after surgery for CSM.

METHOD

In a prospective study, 64 patients with CSM who underwent surgical treatment between October 2006 and April 2008 using an anterior approach were included. Based on the clinical symptoms and signs present, the severity of neurological deficits of all patients was scored according to a modified Japanese Orthopaedic Association scale score for CSM just before the surgery and at 6 months follow-up. Recovery rates were calculated at 6 months.

RESULTS

There were 22 patients who did not have spinal cord intensity changes on MR imaging and 44 who demonstrated high-intensity signal changes on T2-weighted images (focal or segmental). No statistically significant differences were found in recovery rates between cases with T2 signal intensity changes and those with no signal intensity changes. However, the postoperative modified Japanese Orthopaedic Association scale scores and the recovery rates were much lower in patients with multisegmental signal intensity changes compared with those without these changes or those with focal signal intensity change, and ANOVA demonstrated this difference to be statistically significant (p < 0.05).

CONCLUSION

Multisegmental spinal cord signal intensity changes on T2-weighted MR imaging are predictors of a poor outcome in terms of functional recovery rate in patients undergoing operations for CSM.

Prediction of clinical results of laminoplasty for cervical myelopathy focusing on spinal cord motion in intraoperative ultrasonography and postoperative magnetic resonance imaging

STUDY DESIGN

Retrospective analysis of preoperative imaging and clinical data from patients undergoing cervical expansive laminoplasty for cervical myelopathy.

OBJECTIVE

To investigate preoperative parameters that predict the floating status of the spinal cord at the anterior elements of the cervical spine in both intraoperative ultrasonography (US) and postoperative magnetic resonance imaging (MRI), and to evaluate the association between clinical outcome and spinal cord floating.

SUMMARY OF BACKGROUND DATA

Intraoperative US has been used to evaluate the status of the spinal cord after cervical laminoplasty for cervical myelopathy. Few studies have evaluated the predictive preoperative parameters for intraoperative US results.

METHODS

Imaging and clinical outcome data were collected from 101 consecutive patients who underwent cervical expansive laminoplasty for cervical myelopathy at Kaikoukai Nagoya Kyouritsu Hospital, Japan, from April 2004 to April 2008. The preoperative parameters associated with spinal cord floating in intraoperative US and postoperative MR images were investigated. Predictive parameters for the rate of recovery according to the Japanese Orthopedic Association score for cervical myelopathy at each follow-up session were also investigated.

RESULTS

Predictive parameters for spinal cord floating after decompression in intraoperative US were the cervical vertebrae 2 to 7 (C2-C7) sagittal alignment in the standing neutral position on preoperative plain radiograph radiography (cut-off value=3 degrees) and the C5/6 "beak angle" in preoperative MRI (cut-off value=20 degrees). A predictive parameter for spinal cord floating in postoperative MRI was the C5/6 beak angle in preoperative MRI (cut-off value=21 degrees). The preoperative Japanese Orthopedic Association score and spinal cord floating at anterior elements of the cervical spine in intraoperative US were predictive parameters for clinical outcome.

CONCLUSION

Intraoperative US was more useful than postoperative MRI for predicting the clinical outcome of cervical expansive laminoplasty. Knowledge of the predictive parameters for spinal cord floating after cervical expansive laminoplasty could help evaluate the limitations of posterior decompression.

Preoperative patient selection with magnetic resonance imaging, computed tomography, and electroencephalography: does the test predict outcome after cervical surgery?

OBJECT

The objective of this systematic review was to use evidence-based medicine to assess whether preoperative imaging or electromyography (EMG) predicts surgical outcomes in patients undergoing cervical surgery.

METHODS

The National Library of Medicine and Cochrane Database were queried using MeSH headings and keywords relevant to the preoperative imaging and EMG. Abstracts were reviewed after which studies meeting inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons.

RESULTS

Preoperative MR imaging and CT myelography are successful in confirming clinical radiculopathy (Class II). Multilevel T2 hyperintensity, T1 focal hypointensity combined with T2 focal hyperintensity, and spinal cord atrophy each convey a poor prognosis (Class III). There is conflicting data concerning whether focal T2 hyperintensity or cervical stenosis are associated with a worse outcome. Electromyography has mixed utility in predicting outcome (Class III).

CONCLUSIONS

Magnetic resonance imaging or CT myelography are important for preoperative assessment. Magnetic resonance imaging may be helpful in assessing prognosis, whereas EMG has mixed utility in assessing outcome.

Spinal cord morphology and dynamics during cervical laminoplasty: evaluation with intraoperative sonography

STUDY DESIGN

An intraoperative sonographic study for evaluating spinal cord decompression status was conducted.

OBJECTIVES

To analyze the spinal cord decompression status using intraoperative sonography and to evaluate the relation to postoperative neurologic recovery following cervical laminoplasty.

SUMMARY OF BACKGROUND DATA

Since the 1980s, several papers have introduced that the intraoperative ultrasound allowed assessment of the adequacy of decompression and configuration of the spinal cord in compressive myelopathy. However, there have been no reports systematically evaluating the decompression status.

METHODS

Spinal cord decompression status of 80 consecutive patients with cervical compressive myelopathy was evaluated by intraoperative sonography during cervical laminoplasty. The decompression status was classified into 4 grades according to the restoration pattern of the space ventral to the cord. In addition, amplitude of the cord pulsation and compression type in axial view were also assessed. This study analyzed whether those findings from intraoperative sonography had relevance to preoperative spinal cord conditions evaluated by magnetic resonance images (MRI) and postoperative neurologic recovery.

RESULTS

The mean neurologic recovery rate was 48.3% at the final follow-up. According to intraoperative sonographic evaluation, 50 cases who acquired the space ventral to the cord showed significantly higher recovery rate (59.2%) than 30 cases who failed to acquire the space (recovery rate, 31.0%) in total. Twenty-seven of 60 cases with intramedullary T2 high lesion on preoperative MRI more frequently failed to restore the ventral space, and their neurologic recovery rate indicated 30.2%. The amplitude of spinal cord pulsation or compression type did not correlate with the neurologic recovery.

CONCLUSION

Intraoperative sonography during laminoplasty appears to be very useful for evaluating spinal cord decompression status. Our original classification system based on restoration patterns of the space ventral to the spinal cord is considered to be practical for predicting neurologic improvement in cervical compressive myelopathy.

Treatment options and results in cervical myelopathy

Cervical myelopathy is a clinical entity resulting from external compression of the cervical medulla. The clinical course can be divided into the acute form (secondary to trauma) versus subacute (progression within weeks to months) and chronic cervical myelopathy (months to years). The clinical picture of myelopathy is that of unsteady gait with long-tract signs, such as hyperreflexia, spasticity and extensor plantar responses. Between 1997 and 2000, 359 consecutive patients have been operated on in our department presenting with a variety of symptoms related to compression of the cervical medulla. Beside of standard MRI for all patients we applied SSEPs, gait analysis and dynamic MRI studies as additional helpful tools in evaluating selected patients pre- and postoperatively. We prefer the anterior approach as first-line approach because in the majority of patients the osteophytic spurs are more dominant anteriorly, and after anterior decompression and stabilization the posterior approach appears safer. We also favor the more extended approach of spondylectomy versus multilevel decompression in patients with bisegmental or multisegmental spinal canal stenosis. However it seems to be that radicular decompression is better achieved through multilevel decompression than through spondylectomy.