Magnetic resonance imaging findings in ossification of the posterior longitudinal ligament of the cervical spine

Risk factors for the development of degenerative cervical myelopathy: a review of the literature

Degenerative cervical myelopathy (DCM) encompasses various pathological conditions causing spinal cord (SC) impairment, including spondylosis (multiple level degeneration), degenerative disc disease (DDD), ossification of the posterior longitudinal ligament (OPLL), and ossification of the ligamentum flavum (OLF). It is considered the most common cause of SC dysfunction among the adult population. The degenerative phenomena of DDD, spondylosis, OPLL and OLF, is likely due to both inter-related and distinct factors. Age, cervical alignment, and range of motion, as well as congenital factors such as cervical cord-canal mismatch due to congenital stenosis, Klippel-Feil, Ehler-Danlos, and Down syndromes have been previously reported as potential factors of risk for DCM. The correlation between some comorbidities, such as rheumatoid arthritis and movement disorders (Parkinson disease and cervical dystonia) and DCM, has also been reported; however, the literature remains scare. Other patient-specific factors including smoking, participation in contact sports, regular heavy load carrying on the head, and occupation (e.g. astronauts) have also been suggested as potential risk of myelopathy development. Most of the identified DCM risk factors remain poorly studied however. Further researches will be necessary to strengthen the current knowledge on the subject, especially concerning physical labors in order to identify patients at risk and to develop an effective treatment strategy for preventing this increasing prevalent disorder.

Surgical management of ossification of the posterior longitudinal ligament in the cervical spine

OPLL is a progressive process that can result in spinal cord compression and myelopathy. Various surgical approaches for the management of OPLL in the cervical spine exist. Our goal is to present our institution's experience in the management of OPLL over the last 20 years. Sixty-eight patients underwent surgery for cervical OPLL. Mean age at surgery was 56.9 years. No differences between demographic characteristics and surgical approach were identified. There were no significant differences between the approaches regarding the mean estimated blood loss, occurrence of durotomy, reoperation rate, positive K-line and preoperative cervical spine sagittal balance. Number of levels operated on was significantly different (anterior approach 2 ± 0.8 levels, posterior approach 4.3 ± 1.3 levels, combined approach 3.3 ± 0.9 levels, p-value <0.01), but postoperative sagittal balance was not (anterior approach Cobb angle 11.9 ± 5.8 degrees, posterior approach Cobb angle 7 ± 3.5 degrees, combined approach Cobb angle 16.7 ± 7.3 degrees, p-value = 0.09). Functional outcomes were good for 70% of patients and did not significantly differ across approaches (anterior approach 28%, posterior approach 33%, combined approach 9%, p-value = 0.46). Good functional outcomes were more commonly observed in patients with a positive K-line (OR 0.2, 95% CI 0.04-0.9, p-value 0.05) while poor outcomes were most commonly observed in patients with an occupational ratio >0.6 (OR 6.9, 95% CI 1.35-42.7, p-value 0.02). OPLL is a rare disease for which prompt referral for surgical decompression may lead to good clinical outcomes.

False-Positive and False-Negative Results of Motor Evoked Potential Monitoring During Surgery for Intramedullary Spinal Cord Tumors

BACKGROUND

Motor evoked potential (MEP) recording is used as a method to monitor integrity of the motor system during surgery for intramedullary tumors (IMTs). Reliable sensitivity of the monitoring in predicting functional deterioration has been reported. However, we observed false positives and false negatives in our experience of 250 surgeries of IMTs.

OBJECTIVE

To delineate specificity and sensitivity of MEP monitoring and to elucidate its limitations and usefulness.

METHODS

From 2008 to 2011, 58 patients underwent 62 surgeries for IMTs. MEP monitoring was performed in 59 operations using transcranial electrical stimulation. Correlation with changes in muscle strength and locomotion was analyzed. A group undergoing clipping for unruptured aneurysms was compared for elicitation of MEP.

RESULTS

Of 212 muscles monitored in the 59 operations, MEP was recorded in 150 (71%). Positive MEP warnings, defined as amplitude decrease below 20% of the initial level, occurred in 37 muscles, but 22 of these (59%) did not have postoperative weakness (false positive). Positive predictive value was limited to 0.41. Of 113 muscles with no MEP warnings, 8 muscles developed postoperative weakness (false negative, 7%). Negative predictive value was 0.93. MEP responses were not elicited in 58 muscles (27%). By contrast, during clipping for unruptured aneurysms, MEP was recorded in 216 of 222 muscles (96%).

CONCLUSION

MEP monitoring has a limitation in predicting postoperative weakness in surgery for IMTs. False-positive and false-negative indices were abundant, with sensitivity and specificity of 0.65 and 0.83 in predicting postoperative weakness.

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.

Spinal cord MRI signal changes at 1 year after cervical decompression surgery is useful for predicting midterm clinical outcome: an observational study using propensity scores

BACKGROUND CONTEXT

There is little information on the relationship between magnetic resonance imaging (MRI) T2-weighted high signal change (T2HSC) in the spinal cord and surgical outcome for cervical myelopathy. We therefore examined whether T2HSC regression at 1 year postoperatively reflected a 5-year prognosis after adjustment using propensity scores for potential confounding variables, which have been a disadvantage of earlier observational studies.

PURPOSE

The objective of this study was to clarify the usefulness of MRI signal changes for the prediction of midterm surgical outcome in patients with cervical myelopathy.

STUDY DESIGN/SETTING

This is a retrospective cohort study.

PATIENT SAMPLE

We recruited 137 patients with cervical myelopathy who had undergone surgery between 2007 and 2012 at a median age of 69 years (range: 39-87 years).

OUTCOME MEASURES

The outcome measures were the recovery rates of the Japanese Orthopaedic Association (JOA) scores and the visual analog scale (VAS) scores for complaints at several body regions.

MATERIALS AND METHODS

The subjects were divided according to the spinal MRI results at 1 year post surgery into the MRI regression group (Reg+ group, 37 cases) with fading of T2HSC, or the non-regression group (Reg- group, 100 cases) with either no change or an enlargement of T2HSC. The recovery rates of JOA scores from 1 to 5 years postoperatively along with the 5-year postoperative VAS scores were compared between the groups using t test. Outcome scores were adjusted for age, sex, diagnosis, symptom duration, and preoperative JOA score by the inverse probability weighting method using propensity scores.

RESULTS

The mean recovery rates in the Reg- group were 35.1%, 34.6%, 27.6%, 28.0%, and 30.1% from 1 to 5 years post surgery, respectively, whereas those in the Reg+ group were 52.0%, 52.0%, 51.1%, 49.0%, and 50.1%, respectively. The recovery rates in the Reg+ group were significantly higher at all observation points. At 5 years postoperatively, the VAS score for pain or numbnessin the arms or hands of the patients in the Reg+ group (24.7 mm) was significantly milder than that of the patients in the Reg- group (42.2 mm).

CONCLUSIONS

Spinal T2HSC improvement at 1 year postoperatively may predict a favorable recovery until up to 5 years after surgery.

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.

Decreased DNA methylation in the promoter region of the WNT5A and GDNF genes may promote the osteogenicity of mesenchymal stem cells from patients with ossified spinal ligaments

Mesenchymal stem cells (MSCs) isolated from spinal ligaments with ectopic ossification have a propensity toward the osteogenic lineage. To explore epigenetic control of the osteogenic features of MSCs, we treated MSCs obtained from the spinal ligaments of ossification of yellow ligament (OYL) patients and non-OYL patients with the DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5AdC). We compared the non-OYL groups (untreated and treated with 5AdC) with the OYL groups (untreated and treated with 5AdC) by genome-wide microarray analysis. Next, we used methylated DNA immunoprecipitation combined with quantitative real-time PCR to assess gene methylation. Ninety-eight genes showed expression significantly increased by 5AdC treatment in MSCs from non-OYL patients but not from OYL patients. In contrast, only two genes, GDNF and WNT5A, showed significantly higher expression in OYL MSCs compared with non-OYL MSCs without 5AdC treatment. Both genes were hypermethylated in non-OYL MSCs but not in OYL MSCs. Small interfering RNA targeted to each gene decreased expression of the target gene and also several osteogenic genes. Both small interfering RNAs also suppressed the activity of alkaline phosphatase, a typical marker of osteogenesis. These results suggest that the osteogenic features of MSCs from OYL patients are promoted by unmethylated WNT5A and GDNF genes.

Surgical outcome in patients with cervical ossified posterior longitudinal ligament: A single institutional experience

OBJECTIVE

Ossification of the posterior longitudinal ligament (OPLL) is a complex multi-factorial disease process having both metabolic and biomechanical factors. The role of surgical intervention as well as the choice of approach weather anterior or posterior is ambiguous. The objective of this study was to assess the surgical out come and post operative functional improvement in patients with cervical OPLL at a tertiary care centre.

PATIENTS AND METHODS

This prospective study included 63 patients of cervical OPLL who underwent either anterior and/or posterior surgeries in Department of Neurosurgery, Nizam's Institute of Medical Sciences, Hyderabad between June 2009 to May 2011. Patient's data including age, sex, pre and post operative functional status, radiographic findings and OPLL subtypes were recorded and analyzed over a follow up ranging up to minimum two years.

RESULTS

The mean age of the patients was 51.1 (range 30-80 years) involving 14 women and 49 men. Out of 63 patients, 14 patients underwent surgery by anterior approach (corpectomy and fusion) and all of them improved (P = 0.52). 49 patients underwent surgery by posterior approach where decompressive laminectomy was performed in 40, laminectomy with instrumentation was done in 5, laminoplasty was done in 3 and 1 patient underwent both anterior and posterior surgeries. Of those who underwent posterior surgery, 40 patients improved, 7 remained the same as their preoperative status (who were having signal intensity changes on T2W MRI) and 2 patients deteriorated in the immediate post operative period and then showed gradual improvement. All the patients were followed up for 24 months. The mean pre-operative Nurick grade was 2.82 which later on improved to 2.03 post surgery (P < 0.05). Minor complications included wound infections in two patients (1.26%).

CONCLUSIONS

Anterior cervical decompression and reconstruction is a safe and appropriate treatment for cervical spondylitic myelopathy in the setting of single or two level OPLL. Laminectomy or laminoplasty is indicated in patients with preserved cervical lordosis having three or more levels of involvement. Younger patients with good pre operative functional status and less than 2 levels of involvement have better outcome following anterior surgery.

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.

Analysis of demographics, clinical, and radiographical findings of ossification of posterior longitudinal ligament of the cervical spine in 146 Korean patients

STUDY DESIGN

Retrospective clinical data analysis.

OBJECTIVE

This study was conducted to analyze retrospectively the demographics, clinical presentation, and radiographical findings of ossification of posterior longitudinal ligament (OPLL) of the cervical spine in Korean patients, which could serve as a basis for further studies on and treatment of OPLL.

SUMMARY OF BACKGROUND DATA

As the frequency of diagnosing the OPLL has been gradually increasing because of the increased importance and interest, it is important to understand the demographic characteristics of the disease.

METHODS

Of 222 patients with a diagnosis of OPLL of the cervical spine, 146 patients were evaluated. Demographic features such as age and sex, and clinical features related to symptoms and treatments, were analyzed, and radiological features observed on plain radiographs, computerized tomography for 3-dimensional reconstruction, and magnetic resonance images were investigated.

RESULTS

Of the 146 subjects, 106 were male patients and 40 were female patients, which showed a male to female ratio of 2.65:1. The mean age of the subjects was 53.3 years. Neurological symptoms such as radiculopathy or myelopathy were observed in 109 patients (74.7%). Diagnosis of OPLL by plain radiography could not be ascertained in 19.9% of the patients. Ossification of paraspinal ligaments also accompanied OPLL in 86.3% of the subjects. Intramedullary high-signal intensity on T2-weighted sagittal plane magnetic resonance images was shown in 62 patients (42.5%). Concurrent herniated intervertebral disc was observed in 37 patients (25.3%).

CONCLUSION

The demographics, clinical presentation, and radiographical findings of OPLL of the cervical spine in Korean patients were analyzed, which could serve as a basis for further study on and treatment of OPLL. The classification method using plain radiographs has some limitation for disease treatment or prognosis. For the exact diagnosis and classification of the OPLL, computerized tomographic scan is more useful.

Diagnosis of Cervical OPLL in Lateral Radiograph and MRI: Is it Reliable?

OBJECTIVE

Cervical OPLL is a relatively common cause of developing cervical myelopathy or radiculopathy in Asians. Cervical OPLL is sometimes missed in lateral radiography or MRI. In the present study, we analyzed the diagnostic accuracy of cervical OPLL in lateral radiography and MRI compared to CT scan.

METHODS

This is a retrospective study of forty-six patients who underwent decompressive surgery anteriorly or posteriorly in our institute. All patients were diagnosed with cervical OPLL by CT scan. The patients were grouped into continuous type, segmental type, mixed type, and localized type. We then evaluated lateral radiographs and MRI compared to CT scans. The diagnostic accuracy and false negative rates in lateral radiograph and MRI were evaluated.

RESULTS

In a total of 46 patients diagnosed with cervical OPLL in CT scans, diagnostic accuracy using lateral radiograph and MRI were 52.2%(24/46) and 58.7%(27/46), respectively. In the continuous type group, diagnostic accuracy using lateral radiograph and MRI were 85.7%(6/7) and 100.0%(7/7). In the segmental type group, diagnostic accuracy using lateral radiograph and MRI were 27.3%(6/22) and 31.8%(7/22). In the mixed type group, diagnostic accuracy was 91.7%(11/12) in lateral radiograph and 83.3%(10/12) in MRI. In the localized group, diagnostic accuracy was 20.0%(1/5) in lateral radiograph and 60.0%(3/5) in MRI.

CONCLUSION

The diagnostic accuracy of cervical OPLL using lateral radiograph and MRI was less than using CT scan. For the best treatment plan, preoperative CT scan should be performed to detect conditions of ossifications such as cervical OPLL.

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.

Analysis of demographics, risk factors, clinical presentation, and surgical treatment modalities for the ossified posterior longitudinal ligament

OBJECT

Ossification of the posterior longitudinal ligament (OPLL) is a rare disease that results in progressive myeloradiculopathy related to pathological ossification of the ligament from unknown causes. Although it has long been considered a disease of Asian origin, this disorder is increasingly being recognized in European and North American populations. Herein the authors present demographic, radiographic, and comorbidity data from white patients with diagnosed OPLL as well as the outcomes of surgically treated patients.

METHODS

Between 1999 and 2010, OPLL was diagnosed in 36 white patients at Barrow Neurological Institute. Patients were divided into 2 groups: a group of 33 patients with cervical OPLL and a group of 3 patients with thoracic or lumbar OPLL. Fifteen of these patients who had received operative treatment were analyzed separately. Imaging analysis focused on signal changes in the spinal cord, mass occupying ratio, signs of dural penetration, spinal levels involved, and subtype of OPLL. Surgical techniques included anterior cervical decompression and fusion with corpectomy, posterior laminectomy with fusion, posterior open-door laminoplasty, and anterior corpectomy combined with posterior laminectomy and fusion. Comorbidities, cigarette smoking, and previous spine surgeries were considered. Neurological function was assessed using a modified Japanese Orthopaedic Association Scale (mJOAS).

RESULTS

A high-intensity signal on T2-weighted MR imaging and a history of cervical spine surgery correlated with worse mJOAS scores. Furthermore, mJOAS scores decreased as the occupying rate of the OPLL mass in the spinal canal increased. On radiographic analysis, the proportion of signs of dural penetration correlated with the OPLL subtype. A high mass occupying ratio of the OPLL was directly associated with the presence of dural penetration and high-intensity signal. In the surgical group, the rate of neurological improvement associated with an anterior approach was 58% compared with 31% for a posterior laminectomy. No complications were associated with any of the 4 types of surgical procedures. In 3 cases, symptoms had worsened at the last follow-up, with only a single case of disease progression. Laminoplasty was the only technique associated with a worse clinical outcome. There were no statistical differences (p > 0.05) between the type of surgical procedure or radiographic presentation and postoperative outcome. There was also no difference between the choice of surgical procedure performed and the number of spinal levels involved with OPLL.

CONCLUSIONS

Ossification of the posterior longitudinal ligament can no longer be viewed as a disease of the Asian population exclusively. Since OPLL among white populations is being diagnosed more frequently, surgeons must be aware of the most appropriate surgical option. The outcomes of the various surgical treatments among the different populations with OPLL appear similar. Compared with other procedures, however, anterior decompression led to the best neurological outcomes.

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.

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.

Choice of surgical approach for ossification of the posterior longitudinal ligament in combination with cervical disc hernia

Ossification of the posterior longitudinal ligament (OPLL) is a common spinal disorder that presents with or without cervical myelopathy. Furthermore, there is evidence suggesting that OPLL often coexists with cervical disc hernia (CDH), and that the latter is the more important compression factor. To raise the awareness of CDH in OPLL for spinal surgeons, we performed a retrospective study on 142 patients with radiologically proven OPLL who had received surgery between January 2004 and January 2008 in our hospital. Plain radiograph, three-dimensional computed tomography construction (3D CT), and magnetic resonance imaging (MRI) of the cervical spine were all performed. Twenty-six patients with obvious CDH (15 of segmental-type, nine of mixed-type, two of continuous-type) were selected via clinical and radiographic features, and intraoperative findings. By MRI, the most commonly involved level was C5/6, followed by C3/4, C4/5, and C6/7. The areas of greatest spinal cord compression were at the disc levels because of herniated cervical discs. Eight patients were decompressed via anterior cervical discectomy and fusion (ACDF), 13 patients via anterior cervical corpectomy and fusion (ACCF), and five patients via ACDF combined with posterior laminectomy and fusion. The outcomes were all favorable. In conclusion, surgeons should consider the potential for CDH when performing spinal cord decompression and deciding the surgical approach in patients presenting with OPLL.

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.

Transient long segment spinal cord hyperintensity after anterior cervical discectomy

A 69-year-old man was admitted to our hospital with progressive numbness in both feet and gait disturbance. MR imaging revealed a large cervical disc herniation resulting in significant spinal cord compression with hyperintensity of the spinal cord on T2-weighted images at C-5/6. Immediately after undergoing anterior cervical discectomy, the patient developed severe weakness of his left hand and lower extremities. MR imaging obtained 5 days after surgery revealed a long segment hyperintensity between C-3 and T-2 on T2-weighted images. This long segment hyperintensity disappeared after 2 weeks of steroid administration. We suspect that the persistent, localised, patchy C-5/6 cord hyperintensity represents spinal cord degeneration due to ischaemia and trauma resulting from the disc herniation. However, the transient long segment hyperintensity may represent oedema, probably due to minor trauma of an already compromised cord, during the decompression surgery. Clinicians should be aware that even careful surgery can result in a significant change in radiological studies and neurological condition.

Unilateral hyperplasia of a cervical spinous process as a rare congenital variant of the spine

Congenital variants of the cervical spine may mimic traumatic lesions and may cause recurrent episodes of pain. We report a 24-year-old female patient with chronic neck pain who had marked unilateral hyperplasia of the spinous process of the seventh cervical vertebra. CT and MRI clearly depicted the abnormality and, furthermore, ruled out posttraumatic spinal changes. To our knowledge, our case is the first patient reported with this rare congenital variant diagnosed by cross-sectional imaging.

Cervical cord compression secondary to ossification of the posterior longitudinal ligament

STUDY DESIGN

Resident's case problem.

BACKGROUND

A 52-year-old Chinese male with a 10-year history of gradually worsening right hip stiffness, weakness, and pain was referred to physical therapy by his orthopedist, who made a diagnosis of developmental dysplasia of the right hip, with possible Legg-Calve-Perthes disease. The patient reported multiple falls over the last several years and a gradual onset of low back pain with an onset of "electricity" down both legs. The patient also reported mild numbness in both forearms and the right hand over the previous several months. This resident's case problem illustrates how a physical therapist recognized the presence of an atypical musculoskeletal pathology through the use of hypothesis-driven clinical reasoning and detailed physical examination.

DIAGNOSIS

Examination of the patient's lumbar and cervical spine and hips revealed joint dysfunctions. Neurological testing revealed hyperreflexia. Special testing revealed lower extremity clonus with a positive Babinski sign with gait disturbances. The patient was referred back to his primary physician and then to a neurologist and neurosurgeon. An MRI revealed cervical myelopathy due to ossification of the posterior longitudinal ligament from C3/C4 to C5/C6. The patient then underwent a C3 through C7 laminectomy.

DISCUSSION

It is always imperative that sound clinical reasoning be used when performing physical therapy evaluations, regardless of the referral status of the patient. Patients with nonmusculoskeletal pathology may seek physical therapy services and it is the physical therapist's responsibility to complete a thorough examination and refer to specialists when appropriate.

Factors Affecting Prognosis of Patients Who Underwent Corpectomy and Fusion for Treatment of Cervical Ossification of the Posterior Longitudinal Ligament

OBJECTIVE

Even though cervical ossification of the posterior longitudinal ligament (OPLL) has several unique clinical features compared with spondylotic myelopathy or cervical disc disease, there have been few reports about factors affecting prognosis after decompression using corpectomy. To clarify the prognostic factors for cervical OPLL, the authors analyzed the clinical and radiologic parameters of 47 patients retrospectively.

METHODS

The patients were classified into a good-prognosis group and a poor-prognosis group according to the changes of Nurick grade after operation. Age at operation, gender, preoperative Nurick grade, duration of symptoms, snake-eye appearance, occupying ratio, type of OPLL, Pavlov ratio, and double-layer sign did not affect the prognosis significantly.

RESULTS

Multiple logistic regression analysis revealed that diabetes mellitus (DM) was the only statistically significant factor predicting poor prognosis for the patients with cervical OPLL who underwent corpectomy and fusion.

CONCLUSIONS

Surgeons do not have to be discouraged from performing anterior decompression for the patients with cervical OPLL on the basis of age, severity of disease (preoperative Nurick grade or occupying ratio), irreversible changes in gray matter of the spinal cord (snake-eye appearance), or duration of symptoms. We should direct our attention to DM as a potent risk factor for cervical OPLL and try to clarify the mechanism by which DM possibly affected the functional recovery of the patients.

Spinal canal size in ossification of the posterior longitudinal ligament of the cervical spine

BACKGROUND

The size of the spinal canal is a factor that contributes to the neurologic deficits associated with cervical ossification of the posterior longitudinal ligament (OPLL).

METHODS

Bone-window computed tomography (CT) examinations of the cervical spine in 64 patients with cervical OPLL were reviewed. Forty-two patients underwent surgical treatment (anterior decompression: 16 patients, posterior decompression: 26 patients). The remaining 22 patients were managed conservatively. Selection of the surgical approach, anterior or posterior, was based on the longitudinal extent of cord compression.

RESULTS

The mean developmental size of the spinal canal in the posterior decompression group (10.7 mm at C4) was significantly smaller than the other 2 groups. The spinal canal was narrowed by OPLL to 2.9 to 10.0 mm. The proportion of the patients showing motor deficits of the lower extremities significantly increased when the sagittal canal diameter was narrowed to less than 8 mm.

CONCLUSIONS

This study demonstrates critical values of CT-determined spinal canal stenosis. Developmental size of the spinal canal and the residual anterior-posterior canal diameters resulting from OPLL spinal cord compression are important factors influencing clinical management and the neurologic state.

Acute cervical cord injury associated with ossification of the posterior longitudinal ligament

OBJECTIVE

Patients with ossification of the posterior longitudinal ligament (OPLL) sometimes present with acute spinal cord injury caused by only minor trauma. In the present study, we reviewed our experience of acute cervical cord injury associated with OPLL to understand the pathomechanisms and to provide clinical information for management of this disorder.

METHODS

Twenty-eight patients were retrospectively analyzed. There were 26 men and 2 women, aged 45 to 78 years (mean, 63.0 yr). Most patients experienced incomplete spinal cord injury (Frankel Grade A, 3; B, 1; C, 15; and D, 9).

RESULTS

Radiological studies revealed continuous- or mixed-type OPLL in 14 patients and segmental-type OPLL in 14 patients. The sagittal diameter of the spinal canal was reduced to 4.1 to 10 mm at the narrowest level as a result of OPLL. Developmental size of the spinal canal was significantly smaller in the group with segmental OPLL. Magnetic resonance imaging scans revealed that spinal cord injury occurred predominantly at the caudal edge of continuous-type OPLL or at the disc levels. Surgery was performed in 24 patients either by posterior (18 patients) or anterior (6 patients) decompression at various time intervals after the trauma. Twenty patients (71%) displayed improvement in Frankel grade.

CONCLUSION

The present study demonstrates the preexisting factors and pathomechanisms of acute spinal cord injury associated with cervical OPLL. Magnetic resonance imaging is useful to understand the level and mechanism of injury. Further investigation will be needed to elucidate the role of surgical decompression.

Spinal cord edema: unusual magnetic resonance imaging findings in cervical spondylosis

OBJECT

Spinal cord edema is a rare radiological finding in chronic degenerative disorders of the spine. Between 1997 and 2001, the authors treated six patients with cervical spondylotic myelopathy in whom postoperative spinal cord edema was demonstrated. The authors describe the radiological and clinical features of this unusual condition.

METHODS

The six patients were all men, and ranged in age from 44 to 72 years. All patients presented with mild quadriparesis and underwent laminoplasty or anterior fusion. Preoperative magnetic resonance (MR) imaging revealed marked spinal cord compression with intramedullary hyperintensity on T2-weighted sequences and spinal cord enhancement at the compression level after administration of Gd. After surgery, spinal cord edema was observed in all patients; the spinal cord appeared swollen on the postoperative MR images. Preoperative and postoperative Gd-enhanced MR imaging demonstrated clear enhancement of the white matter at the compressed segment Neurologically, five of six patients experienced good improvement of symptoms; however, the spinal cord edema as documented on follow-up MR imaging persisted for several months after surgery.

CONCLUSIONS

The radiological characterization of spinal cord edema was based on the reversible white matter lesion most likely caused by disturbed local venous circulation induced by chronic spinal cord compression. Such unusual MR findings in cervical spondylotic myelopathy should be differentiated from intramedullary spinal cord tumors, demyelinating disorders, or inflammatory processes.

Diagnosis and surgical management of cervical ossification of the posterior longitudinal ligament

BACKGROUND CONTEXT

The diagnosis and treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL) is continuing to evolve as its effects become more readily recognized and surgical alternatives expand.

PURPOSE

To review the clinical, neurodiagnostic and surgical management of OPLL.

STUDY DESIGN/SETTING

Patients with early OPLL, often in their mid-forties, present with radiculopathy or mild/moderate myelopathy. Radiographically, hypertrophy of the posterior longitudinal ligament with punctate ossification appears opposite multiple disc spaces. Patients with classic OPLL frequently become symptomatic in their mid-fifties with radiographic characteristics showing ossification of the ligament behind the vertebrae alone (segmental), behind the vertebrae including the intervertebral disc spaces (continuous), and combinations of the segmental and continuous variants and OPLL opposite disc spaces alone. Both magnetic resonance imaging (MRI) and computed tomography (CT) examinations are critical. MRI better delineates the extent of soft tissue abnormalities in three dimensions, including the cervicothoracic junction, whereas CT more readily identifies the foci of frank ossification. Surgical alternatives include anterior, posterior or combined approaches. Anterior surgical options include plated multilevel anterior discectomy and fusion, anterior cervical corpectomy with fusion (ACF), or plated multilevel ACF with differing posterior fusion techniques. Posterior surgical options vary from laminectomy with or without simultaneous fusion and laminoplasty. Although outcomes with different approaches vary, many direct anterior resection techniques achieve more favorable results because of appropriate and adequate resection of the ligament.

CONCLUSIONS

The clinical and neuroradiographic documentation of OPLL and its appropriate surgical management anteriorly, posteriorly or circumferentially remain a therapeutic challenge.

Ossification of the cervical posterior longitudinal ligament: a review

Ossification of the cervical posterior longitudinal ligament (OPLL) represents a continuum beginning with hypertrophy of the posterior longitudinal ligament (PLL) followed by progressive coalescence of centers of chondrification and ossification. Early OPLL mimicking disc disease appears opposite multiple disc spaces associated with significant retrovertebral extension, helping to differentiate it from spondylosis. On computerized tomography examinations, the single- and double-layer signs indicate possible dural penetration with the increased potential for an intraoperative cerebrospinal fluid fistula during dissection. Direct ventral resection of OPLL in patients younger than 65 years of age is optimal and includes single- or multilevel anterior corpectomy with fusion, the latter accompanied by posterior fusion. For patients older than the age of 65 years, with a well-preserved cervical lordosis, laminectomy with or without fusion and/or laminoplasty may suffice in providing indirect dorsal decompression. Patients undergoing circumferential procedures with halo devices are managed with a specific anesthetic protocol, including awake intubation and positioning with intraoperative monitoring of somatosensory evoked potentials, electromyography, and the option of undergoing motor evoked potential monitoring. Intubation is maintained during the 1st postoperative night. When circumferential procedures are performed intubation is always maintained during the 1st postoperative night, and fiberoptic postoperative extubation is electively performed by specifically trained anesthesiologists when deemed appropriate. Patients exhibiting three or more major risk factors are considered candidates for delayed extubation and rarely, tracheostomy. Repeated anterior surgery, operations lasting more than 10 hours, involving four or more levels (including C-2), obesity, asthma, and blood transfusions of more than 4 U (1000-1200 ml) are all considered major risk factors.

Identification of ossification of the posterior longitudinal ligament extending through the dura on preoperative computed tomographic examinations of the cervical spine

STUDY DESIGN

To establish the diagnosis of dural penetration on preoperative computed tomographic studies of the cervical spine in patients with ossification of the posterior longitudinal ligament (OPLL).

OBJECTIVES

To define before surgery the pathognomonic computed tomographic findings of OPLL extending to and through the dura.

SUMMARY OF BACKGROUND DATA

On preoperative computed tomographic studies, Hida et al have described the single-layer sign characterized by a solid mass of hyperdense OPLL and the double-layer sign defined by two (anterior and posterior) ossified rims surrounding a central nonossified but hypertrophied posterior longitudinal ligament. Only 1 of the 9 patients exhibiting the single-layer sign but 10 of 12 patients showing the double-layer sign had no separate dural plane identified at surgery.

METHODS

Only 2 of 54 patients undergoing multilevel cervical circumferential OPLL procedures had absent dura at surgery. Computed tomographic examinations for all patients were retrospectively reviewed to determine unique signs of dural penetration.

RESULTS

Dura was absent in 1 of 12 patients who had the single-layer CT sign that was additionally characterized by an irregular C angular configuration. Only 1 of 4 patients exhibiting the double-layer computed tomographic sign had absent dura at surgery. The remaining 38 patients had the smooth-layer sign, characterized by more regular margins of classic (22 patients) or early OPLL (16 patients).

CONCLUSIONS

The double-layer computed tomographic sign is more pathognomonic for dural penetration than the single-layer sign. The smooth-layer sign, indicating a clean dural plane, is more typical in North American patients.

Acute cervical cord injury without fracture or dislocation of the spinal column

OBJECT

It is known that the spinal cord can sustain traumatic injury without associated injury of the spinal column in some conditions, such as a flexible spinal column or preexisting narrowed spinal canal. The purpose of this study was to characterize the clinical features and to understand the mechanisms in cases of acute cervical cord injury in which fracture or dislocation of the cervical spine has not occurred.

METHODS

Eighty-nine patients who sustained an acute cervical cord injury were treated in our hospitals between 1990 and 1998. In 42 patients (47%) no bone injuries of the cervical spine were demonstrated, and this group was retrospectively analyzed. There were 35 men and seven women, aged 19 to 81 years (mean 58.9 years). The initial neurological examination indicated complete injury in five patients, whereas incomplete injury was demonstrated in 37. In the majority of the patients (90%) the authors found degenerative changes of the cervical spine such as spondylosis (22 cases) or ossification of the posterior longitudinal ligament (16 cases). The mean sagittal diameter of the cervical spinal canal, as measured on computerized tomography scans, was significantly narrower than that obtained in the control patients. Magnetic resonance (MR) imaging revealed spinal cord compression in 93% and paravertebral soft-tissue injuries in 58% of the patients.

CONCLUSIONS

Degenerative changes of the cervical spine and developmental narrowing of the spinal canal are important preexisting factors. In the acute stage MR imaging is useful to understand the level and mechanisms of spinal cord injury. The fact that a significant number of the patients were found to have spinal cord compression despite the absence of bone injuries of the spinal column indicates that future investigations into surgical treatment of this type of injury are necessary.

Anterior cervical diskectomy and fusion without plate instrumentation in 178 patients

Between 1989 and 1996, fusion, pseudarthrosis, repeated operation rates, and outcomes were studied in 178 patients undergoing one- to four-level (average, 2.2 levels) anterior cervical diskectomy and fusion (ADF) without plating. Dynamic radiographs taken 3 and 6 months after operation showed fusion or pseudarthrosis without motion in 99% of patients after one-level ADF (78 patients), in 90% after two-level ADF (84 patients), and in 100% after three-level ADF (12 patients) and four-level ADF (4 patients). Pseudarthrosis with motion was noted in 1% after one-level ADF and in 10% after two-level ADF (statistically significant with a lower pseudarthrosis rate in the 1-level; by Fisher's exact test, p = 0.0351). Three patients required secondary posterior wiring and fusion. Good or excellent outcomes (by Odom's criteria) were achieved in 96% of patients within an average of 82 months. Although fusion rates for one-level ADF without plates appear adequate, high pseudarthrosis rates after two-level ADF warrant that plating be considered.

Symptomatic ossification of the posterior longitudinal ligament of the cervical spine: pictorial essay

Symptomatic ossification of the posterior longitudinal ligament (OPLL) of the cervical spine is a rare but well-documented condition. It is the causative factor in up to 5% of cases presenting with cervical radiculopathy or myelopathy. Computed tomography is the modality of choice in showing the distinctive characteristics and extent of the disease. Magnetic resonance imaging (MRI) is sensitive in detecting cord compression and its attendant complications. Cervical OPLL commonly affects those of middle and advanced age, and the condition is noted to be particularly common in Japanese, although other racial groups are also affected. A 'mushroom' or 'hill' shape on axial CT typifies OPLL. A sharp radiolucent line separating the posterior vertebral margin from the superficial component of the ossified ligament is a characteristic feature.

Symptomatic ossification of the posterior longitudinal ligament of the lumbar spine. Case report

The authors report a case of focal ossification of the posterior longitudinal ligament (OPLL) behind the L-3 vertebral body. This is relatively rare among previously reported cases in the literature. Magnetic resonance (MR) imaging revealed that the ossifying portion of the PLL was impinging on the left L-3 nerve root. Contrast enhancing hypertrophic PLL was also demonstrated around the ossification and along the lumbosacral PLL. Via a laminectomy and wide excision of the PLL the lesion was removed. Pathological examination revealed a nodule composed of fibrous cartilage, lamina bone, and mature fat marrow. Enchondral ossification could be identified under a microscope. The authors believe that preoperative MR imaging evaluation is important for the detection of the relationship between an OPLL and the neural structure. Excision of the symptomatic OPLL should be performed when needed to obtain adequate nerve root decompression.