Thoracic myelopathy caused by ossification of the ligamentum flavum

Degenerative Thoracic Myelopathy: A Scoping Review of Epidemiology, Genetics, and Pathogenesis

STUDY DESIGN

Literature Review.

OBJECTIVE

Myelopathy affecting the thoracic spinal cord can arise secondary to several aetiologies which have similar presentation and management. Consequently, there are many uncertainties in this area, including optimal terminology and definitions. Recent collaborative cervical spinal research has led to the proposal and subsequent community adoption of the name degenerative cervical myelopathy(DCM), which has facilitated the establishment of internationally-agreed research priorities for DCM. We put forward the case for the introduction of the term degenerative thoracic myelopathy(DTM) and degenerative spinal myelopathy(DSM) as an umbrella term for both DCM and DTM.

METHODS

Following PRISMA guidelines, a systematic literature search was performed to identify degenerative thoracic myelopathy literature in Embase and MEDLINE.

RESULTS

Conditions encompassed within DTM include thoracic spondylotic myelopathy, ossification of the posterior longitudinal ligament, ossification of the ligamentum flavum, calcification of ligaments, hypertrophy of ligaments, degenerative disc disease, thoracic osteoarthritis, intervertebral disc herniation, and posterior osteophytosis. The classic presentation includes girdle pain, gait disturbance, leg weakness, sensory disturbance, and bladder or bowel dysfunction, often with associated back pain. Surgical management is typically favoured with post-surgical outcomes dependent on many factors, including the causative pathology, and presence of additional stenosis.

CONCLUSION

The clinical entities encompassed by the term DTM are interrelated, can manifest concurrently, and present similarly. Building on the consensus adoption of DCM in the cervical spine and the recent proposal of degenerative cervical radiculopathy(DCR), extending this common nomenclature framework to the terms degenerative spinal myelopathy and degenerative thoracic myelopathy will help improve recognition and communication.

Uniportal Thoracic Endoscopic Unilateral Laminotomy with Bilateral Decompression of Thoracic Ossification of Ligamentum Flavum: A Systematic Review of Current Literature

BACKGROUND

Thoracic ossification of ligamentum flavum (TOLF) is a rare disease that often results in worsening neurologic sequelae if left untreated. Although the gold standard treatment for TOLF is open posterior laminectomy, it is often accompanied by high rates of complications and perioperative morbidity. There have been studies looking into feasibility of endoscopic posterior decompression for TOLF, citing potential for lower perioperative morbidity and achieving similar functional outcomes to its open laminectomy counterparts. We provide an up-to-date systematic review of clinical outcomes after endoscopic posterior decompression for TOLF from the latest assemblage of evidence.

METHODS

A systematic review of the technique was conducted from May 2000 to May 2023. Articles were selected based on PRISMA guidelines. Eligibility of studies was independently by 2 reviewers, with disagreements resolved by a third author.

RESULTS

Nineteen primary references comprising 337 patients with TOLF who underwent endoscopic posterior decompression were included in the systematic review. Mean follow-up time across all studies ranged from 8.9 to 65.3 months. Mean age ranged from 51.2 to 63 years, with mean intraoperative blood loss ranging from 15 to 62 mL. There is significant improvement in visual analog scale (VAS) score, VAS back, VAS leg, modified Japanese Orthopaedic Association score, and Oswestry Disability Index compared with preoperative recorded values across all studies, with low rates of complications reported.

CONCLUSIONS

Endoscopic posterior spinal decompression is a safe and effective technique for treatment of TOLF, with a low rate of complications and improvement in pain and function.

Prevalence and distribution of ossification of the ligamenta flava in a 16th-18th century skeletal population sample from Poland

OBJECTIVE

This study aimed to determine the prevalence of the ossification of the ligamenta flava (OLF) among skeletal remains from Poland.

MATERIALS AND METHODS

124 skeletons aged 25 years and older were analyzed. The presence and size of OLF were observed macroscopically. OLF was recorded at the cranial and caudal attachment sites of each vertebra. The following factors were analyzed: age at death, sex, and presence of other spondyloarthropathies.

RESULTS

The crude prevalence of OLF in the analyzed series was 68.55 %. OLF was located most frequently in the lower thoracic spine. A statistically significant relationship was observed between the presence of OLF and age at death. OLF coincided with degenerative spondyloarthropathies of the thoracolumbar spine.

CONCLUSIONS

The results of this study indicate that OLF was not a rare condition in past populations of European ancestry. Analysis of OLF prevalence in skeletal materials can contribute to reconstruction of the conditions and lifestyles of past people.

SIGNIFICANCE

This study shed new light on the prevalence of OLF and provides information on the variability of OLF in past European populations. The evaluation of the prevalence of OLF represents an important contribution to the field of paleopathology in understanding disease changes in prehistoric and historic human populations.

LIMITATIONS

The analyzed material came from unknown populations without demographic data. Sex and age at death were assessed using standard anthropological methods.

SUGGESTIONS FOR FURTHER RESEARCH

It is important to understand the influence of sociocultural factors and physical activity patterns on the development of OLF.

Thoracic Myelopathy in Ossified Ligamentum Flavum: Surgical Management and Long-Term Outcome Following 2 Different Techniques of Surgical Decompression

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Thoracic ossified ligamentum flavum (TOLF) has been reported to present with varying degrees of neuro-deficit and multiple factors have been purported to affect its outcome. Purpose of study was to analyze factors affecting outcome and impact of ultrasonic osteotome (UO).

METHODS

We retrospectively reviewed patients treated for thoracic myelopathy secondary to OLF between 2010 and 2017. 77 patients with complete clinico-radiological records and 2 years follow-up were included. Initial 45 patients, conventional high-speed burr (HSB-group A) was used for decompression. In others, UO was used in combination with HSB (group B). Myelopathy was graded using modified Japanese orthopaedic association grading pre-operatively and each postoperative visit. At final follow-up, recovery rate was calculated. Radiological details including location, morphology, dural ossification, signal change and spinal ossifications were recorded.

RESULTS

Mean mJOA at presentation and final follow-up were 4.3±1.8 and 7.6±1.9 respectively (p = 0.001). HRR was 49.9±23 at final follow-up. A significant reduction in dural tear (12.5%; 29%) and surgical time (125.8±49.5; 189.4±52.5) were observed in group B (p = 0.00). However, there was no statistically significant difference (p = 0.18) in recovery rates between groups A (44.8±26.1) and B (52.8±24.3). Symptom duration (p = 0.00), severity of myelopathy (p = 0.04) and cord signal changes on MRI (p = 0.02) were important predictors of outcome.

CONCLUSION

Use of UO significantly reduced operative time and dural tears, although resulted in similar recovery rate as compared with HSB. Pre-operative severity of myelopathy, symptom duration and presence of cord signal change were the most significant predictors of outcome.

Quantitative physical performance tests can effectively detect Degenerative Cervical Myelopathy: A systematic review and meta-analysis

PURPOSE

This review aimed to identify effective physical performance tests (PPT) as clinical outcome indicators for detecting and monitoring degenerative cervical myelopathy (DCM).

METHODS

A comprehensive literature search was performed on seven electronic databases on the effectiveness in detection and monitoring of DCM by PPT. All included studies were reviewed and undergone quality assessments on the risk-of-bias by Newcastle-Ottawa Scale and were pooled by random-effect analysis with level of significance at 0.05. Homogeneity among studies was assessed by I²-statistics and effect of PPT was confirmed by Cohen's d effect size and confidence intervals.

RESULTS

Totally, 3111 articles were retrieved, and 19 studies were included for review and meta-analysis. There were 13 studies investigating PPT regarding the upper limbs and 12 studies regarding the lower limbs. Performance in 10-second-Grip-and-Release Test (G&R) and 9-Hole-Peg Test (9HPT) was studied in 10 and 3 articles, respectively, while 10-second-Stepping Test (SST), 30-meter-Walking Test (30MWT) and Foot-Tapping Test (FTT) for lower limbs were studied in 5, 4, and 3 articles correspondingly. Only 1 study utilized the Triangle-Stepping Test. High-quality study with fair risk-of-bias was revealed from Newcastle-Ottawa scale. Large effect size facilitated detection and monitoring in DCM was unveiling for G&R, 9HPT, SST, and 30MWT. FTT, while also effective, was hindered by a high-degree heterogeneity in the meta-analysis.

CONCLUSION

Effective PPT including G&R, 9HPT, SST, 30MWT, and FTT was identified for disease detection and monitoring in DCM.

Value of Additional Instrumented Fusion in the Treatment of Thoracic Ossification of the Ligamentum Flavum

Objective

The ossification of the ligamentum flavum (OLF) is one of the major causes of thoracic myelopathy. Surgical decompression with or without instrumented fusion is the mainstay of treatment. However, few studies have reported on the added effect of instrumented fusion. The objective of this study was to compare clinical and radiological outcomes between surgical decompression without instrumented fusion (D-group) and that with instrumented fusion (F-group).

Methods

A retrospective review was performed on 28 patients (D-group, n=17; F-group, n=11) with thoracic myelopathy due to OLF. The clinical parameters compared included scores of the Japanese Orthopedic Association (JOA), the Visual analogue scale of the back and leg (VAS-B and VAS-L), and the Korean version of the Oswestry disability index (K-ODI). Radiological parameters included the sagittal vertical axis (SVA), the pelvic tilt (PT), the sacral slope (SS), the thoracic kyphosis angle (TKA), the segmental kyphosis angle (SKA) at the operated level, and the lumbar lordosis angle (LLA; a negative value implying lordosis). These parameters were measured preoperatively, 1 year postoperatively, and 2 years postoperatively, and were compared with a linear mixed model.

Results

After surgery, all clinical parameters were significantly improved in both groups, while VAS-L was more improved in the F-group than in the D-group (-3.4±2.5 vs. -1.3±2.2, p=0.008). Radiological outcomes were significantly different in terms of changes in TKA, SKA, and LLA. Changes in TKA, SKA, and LLA were 2.3°±4.7°, -0.1°±1.4°, and -1.3°±5.6° in the F-group, which were significantly lower than 6.8°±6.1°, 3.0°±2.8°, and 2.2°±5.3° in the D-group, respectively (p=0.013, p<0.0001, and p=0.037). Symptomatic recurrence of OLF occurred in one patient of the D-group at postoperative 24 months.

Conclusion

Clinical improvement was achieved after decompression surgery for OLF regardless of whether instrumented fusion was added. However, adding instrumented fusion resulted in better outcomes in terms of lessening the progression of local and regional kyphosis and improving leg pain. Decompression with instrumented fusion may be a better surgical option for thoracic OLF.

A systematic review of surgical procedures on thoracic myelopathy

Purpose

The surgical treatment of thoracic myelopathy is still controversial and also a challenge for spine surgeons. Therefore, the objective of this study was to review the related literature on the surgical treatment of thoracic myelopathy and try to define treatment guidelines for spine surgeons on thoracic myelopathy.

Methods

Relevant literatures were searched based on the PubMed, EMBASE, and Cochrane Library between January 2008 and December 2018. Some data on the characteristics of patients were extracted, including number of patients, mean age, surgical procedures, blood loss, complications, and pre-/post-operation modified JOA score. Recovery rate was used to assess the effect of surgery outcome, and the safety was evaluated by blood loss and incidence of complications.

Results

Thirty-five studies met the inclusion criteria and were retrieved. A total of 2183 patients were included in our systematic review, with the average age of 55.2 years. There were 69.8% patients diagnosed as ossification of ligamentum flavum (OLF), 20.0% as ossification of posterior longitudinal ligament (OPLL), 9.3% as disk herniation (DH), and 0.9% as others including diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS). The volume of blood loss was more in the treatment of circumferential decompression (CD) than posterior decompression (PD), and the incidence of complications was higher in CD (P < 0.05). The volume of blood loss in minimally invasive surgery (MIS) was lowest and the incidence of complications was 19.2%. Post-operation recovery rate was 0.49 in PD, 0.35 in CD, and 0.29 in MIS while the recovery rate was 0.54 in PD, 0.55 in CD, and 0.49 in MIS at the last follow-up. When focusing on the OLF specifically, incidence of complications in PD was much lower than CD, with less blood loss and higher recovery rate. Focusing on the OPLL specifically, incidence of complications in PD was much lower than CD, with less blood loss while there was no statistical difference in recovery rate between these two methods.

Conclusions

This systematic review showed that posterior decompression for thoracic myelopathy is safer and better than circumferential decompression according to the complication rate and surgical outcome. And we should also consider the location of compression before the operation.

Microendoscopic Posterior Decompression for Treating Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum: Case Series

Background and Objectives: Ossification of the ligamentum flavum (OLF) is a relatively common cause of thoracic myelopathy. Surgical treatment is recommended for patients with myelopathy. Generally, open posterior decompression, with or without fusion, is selected to treat OLF. We performed minimally invasive posterior decompression using a microendoscope and investigated the efficacy of this approach in treating limited type of thoracic OLF. Materials and Methods: Microendoscopic posterior decompression was performed for 19 patients (15 men and four women) with thoracic OLF with myelopathy aged between 35 to 81 years (mean age, 61.9 years). Neurological examination and preoperative magnetic resonance imaging (MRI) and computed tomography (CT) were used to identify the location and morphology of OLF. The surgery was performed using a midline approach or a unilateral paramedian approach depending on whether the surgeon used a combination of a tubular retractor and endoscope. The numerical rating scale (NRS) and modified Japanese Orthopedic Association (mJOA) scores were compared pre- and postoperatively. Perioperative complications and the presence of other spine surgeries before and after thoracic OLF surgery were also investigated. Results: Four midline and 15 unilateral paramedian approaches were performed. The average operative time per level was 99 min, with minor blood loss. Nine patients had a history of cervical or lumbar spine surgery before or after thoracic spine surgery. The mean pre- and postoperative NRS scores were 6.6 and 5.3, respectively. The mean recovery rate as per the mJOA score was 33.1% (mean follow-up period, 17.8 months), the recovery rates were significantly different between patients who underwent thoracic spine surgery alone (50.5%) and patients who underwent additional spine surgeries (13.7%). Regarding adverse events, one patient experienced dural tear, another experienced postoperative hematoma, and one other underwent reoperation for adjacent thoracic stenosis. Conclusion: Microendoscopic posterior decompression was applicable in limited type of thoracic OLF surgery including beak-shaped type and multi vertebral levels. However, whole spine evaluation is important to avoid missing other combined stenoses that may affect outcomes.

Full-endoscopic decompression for thoracic ossification of ligamentum flavum: surgical techniques and clinical outcomes: A retrospective clinical study

BACKGROUND

Many complications are associated with thoracic open decompression surgery, such as dural tears and neurological deficits. The clinical outcomes are also not satisfactory. Full-endoscopic decompression of the lumbar spinal canal has achieved satisfactory results for the treatment of lumbar spinal stenosis. This surgery may be used for the treatment of thoracic ossification of the ligamentum flavum (OLF) under local anesthesia. The aim of our study is to introduce the surgical techniques used for full-endoscopic decompression for thoracic OLF and to evaluate its safety and efficacy.

METHODS

Fourteen patients with thoracic OLF (4 combined with dural ossification) underwent full-endoscopic decompression surgery. An interlaminar approach was performed. The anchoring method was used to establish the working passage. Spinal cord exposure began at a space between the ossification and the spinal cord, and dorsal and contralateral decompression were performed with the "Over the Top" technique. The modified Japanese Orthopedic Association score (11 points) was used to evaluate the efficacy during follow-up. At the same time, the visual analogue scale score for assessing back pain before and after the operation was evaluated.

RESULTS

The average operation time was 159.73 ± 62.09 minutes, and the hospitalization time was 7.43 ± 1.79 days. The follow-up period ranged from 8 to 22 months. Neurological function was improved. There were no serious complications. Dural tears occurred in 5 patients, intraoperative neurological deterioration occurred in 1 patient, and intraoperative headache and neck pain occurred in 1 patient.

CONCLUSION

Full-endoscopic decompression is an effective, safe surgical technique for thoracic OLF even the cases combined with dural ossification.

Percutaneous full endoscopic posterior decompression of thoracic myelopathy caused by ossification of the ligamentum flavum

PURPOSE

Ossification of ligamentum flavum (OLF) is the leading cause of progressive thoracic myelopathy (TM) in East Asian countries. Surgical decompression is the general treatment for TM. This study investigated the application of percutaneous full endoscopic posterior decompression (PEPD) for the treatment of thoracic OLF.

METHODS

Eighteen patients with TM were treated by PEPD under local anaesthesia. Patients had an average age of 59.1 years and single-level lesions mostly at the lower thoracic vertebrae. Computed tomography and magnetic resonance imaging were used to classify the OLF. The pre- and postoperative neurological statuses were evaluated using the American Spinal Injury Association (ASIA) sensory and motor score, modified Japanese Orthopaedic Association (mJOA) score and Frankel grade.

RESULTS

OLF for all patients was classed as lateral, extended, and enlarged types without comma and tram track signs. Decompression was completed, and a dome-shaped laminotomy was performed through limited laminectomy and flavectomy. Dural tears in 2 patients were the only observed complication. The average score of ASIA sensory and motor, mJOA, as well as the Frankel grade improved significantly after surgery at an average follow-up time of 17.4 months. The average recovery rate (RR) was 47.5% as calculated from the mJOA scores. According to RR, 10 cases were classified as good, 4 cases fair, and 4 cases unchanged.

CONCLUSIONS

For patients with thoracic OLF at a single level and lateral, extended, and enlarged types without comma and tram track signs, it is safe and reliable to perform PEPD, which has satisfactory clinical results. These slides can be retrieved under Electronic Supplementary Material.

Clinical Outcomes and Prognostic Factors in Patients With Myelopathy Caused by Thoracic Ossification of the Ligamentum Flavum

Objective

The objective of this study was to investigate the surgical outcomes and prognostic factors for thoracic ossification of the ligamentum flavum (OLF) after decompressive laminectomy, focusing on the quantitative signal intensity ratio (SIR) of preoperative magnetic resonance imaging (MRI) and its prognostic significance.

Methods

We retrospectively reviewed 24 patients who previously underwent total laminectomy to remove OLF from 2010 to 2015. MRI and computed tomography were performed to detect OLF. The SIR between the regions of interest of high signal intensity lesions and the normal cord at the T1–2 disc levels was calculated. We divided patients into 2 groups based on the extent of the modified Japanese Orthopaedic Association (JOA) recovery rate (RR): good (RR ≥ 50%) and poor (RR < 50%).

Results

The mean preoperative and postoperative modified JOA scores for thoracic myelopathy were 6.67 ± 1.73 and 8.63 ± 1.81, respectively (p < 0.001). The preoperative JOA score (7.5 vs. 5.83, p = 0.028), postoperative JOA score (9.83 vs. 7.42, p = 0.000), and SIR (1.16 vs. 1.41, p = 0.009) were significantly different between the good and poor RR groups. A higher preoperative JOA score and lower SIR were associated with a good RR according to the JOA criteria.

Conclusion

The clinical outcomes for thoracic OLF after decompressive laminectomy were favorable. A higher RR was correlated with a lower SIR and higher preoperative modified JOA score. Therefore, a relatively low SIR on MRI and a relatively high preoperative JOA score could be positive prognostic indicators for the JOA RR in patients with thoracic OLF.

Outcomes and Complications Following Laminectomy Alone for Thoracic Myelopathy due to Ossified Ligamentum Flavum: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

Examine the functional outcomes and complications following laminectomy for thoracic myelopathy due to ossification of the ligamentum flavum (OLF).

SUMMARY OF BACKGROUND DATA

OLF is a rare condition that can cause thoracic myelopathy. Laminectomy is a procedure that can be performed to decompress the spinal cord in patients with thoracic myelopathy due to OLF. Few studies have examined postoperative outcomes and complications following laminectomy for thoracic myelopathy secondary to OLF.

METHODS

A systematic review and meta-analysis was performed. Literature search yielded six studies that met our selection criteria. Study characteristics and baseline patient demographics were extracted from each study. Primary outcomes included pre- and postoperative Japanese Orthopedic Association (JOA) scores and perioperative complications including dural tears, cerebrospinal fluid (CSF) leaks, neurological deficits, surgical site infections, and other complications. We calculated pooled proportion estimates for JOA scores and complications using a random effects model.

RESULTS

A total of 137 patients were included. The pooled pre- and postoperative JOA scores were 5.08 (95% confidence interval [CI], 2.70-7.47; I = 98%) and 8.29 (95% CI, 7.73-8.85; I = 18%), respectively, with a mean improvement of +3.03 points (95% CI, 1.08-4.98; I = 88%). Pooled proportion estimates for dural tears, CSF leaks, infections, and early neurological deficits were 18.4% (95% CI, 12.6-26.1; I = 0%), 12.1% (95% CI, 6.6-21.2; I = 0%), 5.8% (95% CI, 2.1-15.4; I = 0%), and 5.7% (95% CI, 2.2-14.3; I = 0%), respectively.

CONCLUSION

Thoracic myelopathy secondary to OLF can be treated with laminectomy. However, despite some improvement in JOA score, functional status remains poor postoperatively. Perioperative complications are common, with dural tears and CSF leaks occurring most frequently. OLF is an uncommon condition and more research is needed to better understand how we can improve the outcomes of laminectomy alone for the treatment of thoracic myelopathy due to OLF.

LEVEL OF EVIDENCE

3.

Isolated ligamentum flavum ossification in primary hypoparathyroidism

Background:

The ligamenta flava can undergo ossification and calcification resulting in myelopathy. Only seven cases of ligamentum flavum ossification in association with hypoparathyroidism have been reported, most of which had concurrent osseous changes in other spinal ligaments. Here, we report a patient with hypoparathyroidism who presented with ligamentum flavum ossification causing both cervical and thoracic myelopathy.

Case Description:

A 43-year-old male presented with backache, urinary retention, and lower limb weakness for the last few days. Magnetic resonance imaging scan showed ossification of the ligamentum flavum in the cervical and thoracic regions, with severe spinal stenosis. Following spinal decompressive surgery, the patient made a complete recovery. Primary hypoparathyroidism was found to be the underlying cause for ligamentum flavum ossification.

Conclusion:

Ossification of ligamentum flavum secondary to hypoparathyroidism should be considered as a possible cause of myelopathy in all patients presenting with symptoms of spinal cord compression.

Design of mulitlevel OLF approach ("V"-shaped decompressive laminoplasty) based on 3D printing technology

PURPOSE

To introduce a new surgical approach to the multilevel ossification of the ligamentum flavum (OLF) aided by three-dimensional (3D) printing technology.

METHODS

A multilevel OLF patient (male, 66 years) was scanned using computed tomography (CT). His saved DICOM format data were inputted to the Mimics14.0 3D reconstruction software (Materialise, Belgium). The resulting 3D model was used to observe the anatomical features of the multilevel OLF area and to design the surgical approach. At the base of the spinous process, two channels were created using an osteotomy bilaterally to create a "V" shape to remove the bone ligamentous complex (BLC). The decompressive laminoplasty using mini-plate fixation was simulated with the computer. The physical model was manufactured using 3D printing technology. The patient was subsequently treated using the designed surgery.

RESULT

The operation was completed successfully without any complications. The operative time was 90 min, and blood loss was 200 ml. One month after the operation, neurologic function was recovered well, and the JOA score was improved from 6 preoperatively to 10. Postoperative CT scanning showed that the OLF was totally removed, and the replanted BLC had not subsided.

CONCLUSION

3D printing technology is an effective, reliable, and minimally invasive method to design operations. The technique can be an option for multilevel OLF surgical treatment. This can provide sufficient decompression with minimum damage to the spine and other intact anatomical structures.

Clinical Guideline for Treatment of Symptomatic Thoracic Spinal Stenosis

Thoracic spinal stenosis is a relatively common disorder causing paraplegia in the population of China. Until nowadays, the clinical management of thoracic spinal stenosis is still demanding and challenging with lots of questions remaining to be answered. A clinical guideline for the treatment of symptomatic thoracic spinal stenosis has been created by reaching the consensus of Chinese specialists using the best available evidence as a tool to aid practitioners involved with the care of this disease. In this guideline, many fundamental questions about thoracic spinal stenosis which were controversial have been explained clearly, including the definition of thoracic spinal stenosis, the standard procedure for diagnosing symptomatic thoracic spinal stenosis, indications for surgery, and so on. According to the consensus on the definition of thoracic spinal stenosis, the soft herniation of thoracic discs has been excluded from the pathological factors causing thoracic spinal stenosis. The procedure for diagnosing thoracic spinal stenosis has been quite mature, while the principles for selecting operative procedures remain to be improved. This guideline will be updated on a timely schedule and adhering to its recommendations should not be mandatory because it does not have the force of law.

Predictors of surgical outcome in thoracic ossification of the ligamentum flavum: focusing on the quantitative signal intensity

The association between intramedullary increased signal intensity (ISI) on T2-weighted magnetic resonance imaging (MRI) and surgical outcome in thoracic ossification of the ligamentum flavum (OLF) remains controversial. We aimed to determine the impact of signal change ratio (SCR) on thoracic OLF surgical outcomes. We retrospectively reviewed 96 cases of thoracic OLF surgery and investigated myelopathy severity, symptom duration, MRI and computed tomographic findings, surgical technique and postoperative recoveries. Surgical outcomes were evaluated according to the modified Japanese Orthopaedic Association (JOA) score and recovery rate. JOA recovery rate <50% was defined as a poor surgical outcome. By multivariate logistic regression analysis, we identified risk factors associated with surgical outcomes. Forty patients (41.7%) had a recovery rate of <50%. In receiver operating characteristic (ROC) curves, the optimal preoperative SCR cutoff value as a predictor of poor surgical outcome was 1.54. Multivariate logistic regression analysis revealed that a preoperative SCR ≥1.54 and symptom duration >12 months were significant risk factors for a poor surgical outcome. These findings suggest that preoperative SCR and duration of symptoms were significant risk factors of surgical outcome for patients with thoracic OLF. Patients with preoperative SCR ≥1.54 can experience poor postoperative recovery.

Progress on clinical characteristics and identification of location of thoracic ossification of the ligamentum flavum

Thoracic ossification of the ligamentum flavum (TOLF) is the most common cause for thoracic spinal stenosis. TOLF is usually complicated by thoracic disc herniation, ossification of the posterior longitudinal ligament and degenerative spinal diseases such as cervical spondylosis and lumbar spinal stenosis, and the ossification also usually has a discontinuous or continuous multi-segment distribution. The resultant superposition of several symptoms makes the clinical manifestations complex. Currently, the diagnosis of TOLF depends mainly on the patient's symptoms, physical examination and thoracic CT and MRI examinations. Identification of the location of TOLF depends more on the doctor's subjective judgement. Diagnostic problems are related to the specific region and level of surgical decompression: if the extent of decompression is insufficient, the treatment is inadequate, resulting in residual symptoms. Obversely, unnecessary trauma and a various complications will occur if the decompression is too extensive. Hence, the clinical features and process of diagnosis, especially the means of identifying the location, still require further improvement. It is necessary to establish a simple and accurate means of identifying the segment of TOLF that is responsible for the neurologic deficit: a number of spinal surgeons have been working hard on this. This article will provided an overview of the clinical features of TOLF and the related problems of clinical identification of the location of the segment causing the neurological deficit. The relationship between the imaging manifestations and clinical characteristics still need to be explored with the aim of establishing a simple and precise method for determining precisely whether TOLF is related to spinal cord injury or not, thus reducing surgical trauma and achieving an optimal prognosis.

Clinical outcomes after decompressive laminectomy for symptomatic ossification of ligamentum flavum at the thoracic spine

Ossification of the ligamentum flavum (OLF) is a rare disease that causes acquired thoracic spinal canal stenosis and thoracic myelopathy. The aim of this study was to investigate clinical outcomes of symptomatic thoracic OLF treated using posterior decompressive laminectomy. We retrospectively analyzed the medical records of 22 patients who underwent posterior decompressive laminectomy for symptomatic thoracic OLF. The surgical results were evaluated using the modified Japanese Orthopaedic Association (JOA) scoring system and Hirabayashi recovery rate. The intensity of pain was evaluated using a visual analog scale (VAS). The mean duration of follow-up was 35.6months. The mean JOA score was significantly improved at final follow-up (9.18±standard deviation of 1.53 points [range, 6-11 points]) compared with before surgery (5.64±2.04 points [range, 3-9 points]) (P<0.001). The mean Hirabayashi recovery rate was 65.49% (range, 20-100%). Recovery outcomes were excellent in nine patients, good in eight patients, fair in four patients and unchanged in one patient. No patient was classified as deteriorated. The VAS scores were 2.82±3.08 before surgery and 0.59±1.05 at final follow-up (P=0.001). Surgical complications, which resolved after appropriate and prompt treatment, included dural tear in five patients, cerebrospinal fluid leakage in one patient, immediate postoperative neurologic deterioration in one patient, epidural hematoma in one patient, and wound infection in one patient. Our findings suggest that posterior decompressive laminectomy is an effective treatment for symptomatic thoracic OLF and provides satisfactory clinical improvement, but surgery for thoracic OLF is associated with a relatively high incidence of complications.

Clinical characteristics and surgical outcome of thoracic myelopathy caused by ossification of the ligamentum flavum: a retrospective analysis of 85 cases

STUDY DESIGN

A retrospective comparative study.

OBJECTIVES

To describe the clinical features and radiological findings, to assess the safety and effectiveness of posterior decompressive laminectomy and resection of the ossification of the ligamentum flavum (OLF), and to determine which presurgical and surgical variables were most closely related to postsurgical prognosis of thoracic myelopathy (TM) caused by OLF in China.

METHODS

Eighty-five patients with the diagnosis of TM caused by OLF received surgical treatment from July 1998 to May 2012. Clinical data were collected from medical and operative records. Correlations between the surgical outcome and various factors were also analyzed.

RESULTS

All cases were followed up for a mean of 49.2 months (range, 24-190 months) postoperatively. The mean Japanese Orthopaedic Association score was 3.8 points preoperatively and 8.2 points at the final follow-up, yielding a mean recovery rate of 63.0%. Postoperative complications included transient neurological deficits (9 cases), persistent neurological deficits (4 cases), dural tears (17 cases), cerebrospinal fluid leakage (9 cases), wound dehiscence (2 cases) and wound infection (3 cases). The OLF level (middle thoracic), preoperative duration of symptoms, intramedullary signal change on T2WI and preoperative severity of myelopathy were important predictors of surgical outcome.

CONCLUSIONS

Biomechanical and anatomical factors may have a key role in thoracic OLF progression. Posterior decompressive laminectomy and resection of the OLF can be considered an effective, reliable and safe alternative procedure. The OLF level, preoperative duration of symptoms, intramedullary signal change on T2WI and preoperative severity of myelopathy were confirmed and significantly correlated with the surgical outcome.

Microendoscopic posterior decompression for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum: a technical report

PURPOSE

Ossification of the ligamentum flavum (OLF) is a common cause of progressive thoracic myelopathy in East Asia. Good surgical results are expected for patients who already show myelopathy. Surgical decompression using a posterior approach is commonly used to treat OLF. This study investigated the use of microendoscopic posterior decompression for the treatment of thoracic OLF.

METHODS

Microendoscopic posterior decompression was performed on 9 patients with myelopathy. Patients had a mean age of 59.8 years and single-level involvement, mostly at the T10-11 and T11-12 vertebrae. Computed tomography and magnetic resonance imaging were used to classify the OLF. A tubular retractor and endoscopic system were used for microendoscopic posterior decompression. Midline and unilateral paramedian approaches were performed in 2 and 7 patients, respectively. Intraoperative motor evoked potentials (MEPs) of 7 patients were monitored. Pre- and postoperative neurological status was evaluated using the modified Japanese Orthopaedic Association (mJOA) score.

RESULTS

Thoracic OLF for all patients were classed as bilateral type with a round morphology. Improvement of MEPs at least one muscle area was recorded in all patients following posterior decompression. A dural tear in one patient was the only observed complication. The mean recovery rate was 44.9 %, as calculated from mJOA scores at a mean follow-up period of 20 months.

CONCLUSIONS

Microendoscopic posterior decompression combined with MEP monitoring can be used to treat patients with thoracic OLF. The optimal surgical indication is OLF at a single vertebral level and of a unilateral or bilateral nature, without comma and tram track signs, and a round morphology.

Ossification of the ligamentum flavum as cause of thoracic cord compression: Case report of a Latin American man and review of the literature

Background:

Ossification of the ligamentum flavum is a widely described pathology in eastern Asia. Cases have been reported in northern Africa, the Middle-East, India, the Caribbean, Europe, and North America, but no cases from Latin America have been published in the literature. It affects mostly elderly men, with a possible association with obesity and type 2 diabetes.

Case Description:

A 38-year-old previously healthy Latin American male presented to the emergency room department with severe functional disability and a 3/5 paraparesis. Blood reports showed no abnormalities. Computed tomography and magnetic resonance imaging showed a ligamentum flavum ossification with myelopathy. The patient underwent a T3-T9 laminotomy. At hospital discharge, the patient remained with a 3/5 paraparesis, mild hypoesthesia in both lower limbs and bladder incontinence. Rectal sphincter was continent. At 6 months, he was able to walk with a cane, with no sphincter or sensory alterations.

Conclusions:

Ligamentum flavum ossification is rare. To our understanding, this is the first case reported in the Latin American population.

Surgical results and prognostic factors for thoracic myelopathy caused by ossification of ligamentum flavum: posterior surgery by laminectomy

BACKGROUND

Thoracic ossification of ligamentum flavum (TOLF) of the spine is characterized by a heterotopic bone formation in the thoracic ligamentum flavum, which causes slowly progressing spinal cord injury. Surgical decompression is the most common treatment of choice for patients with compressive myelopathy due to TOLF. However, the surgical outcome is not always satisfactory.

METHODS

To identify the predictors of surgical outcome, we retrospectively studied the associations between various clinical and radiological parameters and postoperative recovery in 78 patients who underwent decompressive laminectomy for thoracic myelopathy due to TOLF between October 1998 and June 2011. Surgical outcomes were assessed using modified Japanese Orthopedic Association (mJOA) recovery rate (RR)/outcome scores.

RESULTS

At a minimum of 1 year after surgery for TOLF treatment, the postoperative clinical scores showed statistically significant changes with improvement in the JOA scores. The results indicated that a longer duration of preoperative symptoms, fused-type TOLF, and the degree of compression of the anteroposterior diameter and ossified region (middle thoracic OLF) was related to poor prognosis.

CONCLUSION

Early diagnosis and sufficient surgical decompression improved the functional outcomes of TOLF patients. The surgical risk is relatively higher due to the tenuous blood supply of the spinal cord and the limited spinal canal volume of the middle thoracic spine extending from T4 to T9.

Surgical treatments of myelopathy caused by cervical ligamentum flavum ossification

OBJECTIVE

To present a small case series reporting the outcomes of surgical treatment for myelopathy caused by cervical ossification of the ligamentum flavum (OLF).

METHODS

The authors assessed 15 cases of myelopathy caused by cervical OLF. Patients were eight women and seven men 37-75 years old (mean age 59.7 years). All patients underwent bilateral laminectomy, and the lesions were removed. The decompression range was confined within the medial sides of the bilateral facets and within the involved segments. Intraoperative specimens were examined histologically to confirm the diagnosis. During the operation, the extent of adherence of the lesions to the dura was recorded. The patients were followed for 3-70 months. Neurofunctional improvements were evaluated with the Japanese Orthopaedic Association (JOA) score.

RESULTS

Definite adherences were present in 67.7% of all cases. JOA score showed a 71.5% improvement after operation from a preoperative score of 5-8 (mean 6.4) to a postoperative score of 10-14 (mean 13.5). The operative outcomes were satisfactory without extensive decompression of adjacent segments.

CONCLUSIONS

A high rate of adherence to the dura was observed in patients with myelopathy caused by cervical OLF. Bilateral laminectomy and removal of the lesions, without extensive decompression of adjacent segments, provides an optimistic prognosis.

Ossification of the ligamentum flavum of the thoracic spine in the Korean population

OBJECT

Thoracic ossification of the ligamentum flavum (OLF), a main cause of thoracic myelopathy, is an uncommon disease entity. It is seen mostly in East Asia, although the majority of reports have issued from Japan. In the present study, the clinical features and prognostic factors of thoracic OLF were examined in a large number of Korean patients.

METHODS

Data from 51 consecutive patients who underwent decompressive laminectomy with or without fusion for thoracic OLF between 1998 and 2008 were retrospectively analyzed. Patients were evaluated pre- and postoperatively using the modified Japanese Orthopedic Association (JOA) scale (maximum total score of 11). Patient age, sex, preoperative symptoms, duration of initial symptoms, number of involved segments, duration of follow-up, presence of dural adhesion (dural tearing), intramedullary high signal intensity, morphological classification of OLF (axial or sagittal), coexisting disease, and fusion or no fusion were also evaluated. Surgical outcomes were assessed using JOA recovery rate/outcome scores, and patient satisfaction grades and prognostic factors were analyzed.

RESULTS

There were 18 men and 33 women with a mean age of 60.9 years (range 38-80 years). A mean preoperative JOA score of 5.5 improved to a mean score of 7.4 at the last follow-up (mean 52 months after surgery). The mean duration of the initial symptoms was 34.5 months (range 0.1-240 months) prior to surgery. The most common symptoms were motor dysfunction (80%); sensory deficit (67%); and pain, numbness, and claudication (59%) in the lower extremities. Knee hyperreflexia appeared in 69% of the patients. There were a total of 130 ossified segments, and the mean number of segments per patient was 2.6. Ninety-two (71%) of 130 segments were located below T-8. Recovery outcomes were good (18 patients), fair (16 patients), unchanged (11 patients), or worse (6 patients). Thirty-one patients (61%) were satisfied with their operations. Patients with a beak type of OLF on sagittal MR images experienced a higher recovery rate and a better satisfaction grade than did those with a round OLF. The patients with higher preoperative JOA scores demonstrated significantly higher JOA scores postoperatively (p < 0.001), and the preoperative JOA score had a significant correlation with the recovery rate in patients exhibiting mainly motor dysfunction (p = 0.040, r = 0.330).

CONCLUSIONS

Of the thoracic OLF studies published to date, the present analysis involves the largest Korean population. The most common symptoms of thoracic OLF were motor dysfunction and sensory deficit in the lower extremities, although pain, numbness, and claudication were observed in some patients and were notably accompanied by knee hyperreflexia. At a minimum of 2 years after surgery for thoracic OLF, operative outcomes were generally good, and the prognostic factors affecting good surgical outcomes included a beak type of OLF and a preoperative JOA score > 6.

Clinical analysis of thoracic ossified ligamentum flavum without ventral compressive lesion

The aim of this study was to analyze the clinical characteristics of thoracic ossified ligamentum flavum (OLF) and to elucidate prognostic factors as well as effective surgical treatment modality. The authors analyzed 106 thoracic OLF cases retrospectively from January 1999 to December 2008. The operative (n = 40) and the non-operative group (n = 66) were diagnosed by magnetic resonance imaging (MRI) and/or computed tomography (CT) imaging. We excluded cases exhibiting ventral compressive lesions causing subarachnoid space effacement in thoracic vertebrae as well as those with a coexisting cervical compressive myelopathy. Those in the operative group were treated with decompressive laminectomy as well as resection of OLF. The preoperative neurologic status and postoperative outcomes of patients, as indicated by their modified Japanese Orthopedic Association (mJOA) scores and recovery rate (RR), Modic changes, the axial (fused or non-fused) and sagittal (omega or beak) configurations of OLF, and the ratios of the cross-sectional area (CSA) and anteroposterior diameter (APD) of the most compressed level were studied. The most commonly affected segment was the T10-11 vertebral body level (n = 49, 27.1%) and the least affected segment was the T7-8 level (n = 1, 0.6%). The ratios of the CSA in non-fused and fused types were 77.3 and 59.3% (p < 0.001). When Modic changes were present with OLF, initial mJOA score was found to be significantly lower than those without Modic change (7.62 vs. 9.09, p = 0.033). Neurological status improved after decompressive laminectomy without fusion (preoperative vs. last mJOA; 7.1 ± 2.01 vs. 8.57 ± 1.91, p < 0.001). However, one patient exhibited transient deterioration of her neurological status after surgery. In the axial configuration, fused-type OLF revealed a significant risk for a decreased postoperative mJOA score (0-7, severe and moderate) (Odds ratio: 5.54, χ (2) = 4.41, p = 0.036, 95% CI: 1.014-30.256). The results indicated that the new categorization of axial-type of OLF is a helpful predictor of postoperative patient outcome and fused type was related with poor prognosis. In OLF cases free from ventral lesions compressing the spinal cord, decompressive laminectomy is enough for successful surgical outcome. Therefore, early surgical treatment will be considered in cases with fused-type OLF compressing spinal cord even though they do not have myelopathic symptoms.

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.