A diagnostic study of thoracic myelopathy due to ossification of ligamentum flavum

Treatment of Focal Thoracic Ossification of the Ligamentum Flavum by Percutaneous Posterolateral Transforaminal Endoscopic Surgery Under Local Anesthesia: A Case Series Study

INTRODUCTION

Minimally invasive techniques, such as percutaneous endoscopic discectomy, are increasingly utilized for treating focal thoracic ossification of the ligamentum flavum (TOLF), where their safety and efficacy needs to be further confirmed. The purpose of this study was to investigate the safety and efficacy of percutaneous posterolateral transforaminal endoscopic surgery under local anesthesia for treating focal TOLF.

METHODS

This case series study reviewed medical records of 12 cases diagnosed with focal TOLF who underwent percutaneous posterolateral transforaminal endoscopic surgery under local anesthesia from December 2016 to July 2019 at Fuzhou Second Hospital. Outcomes were functional status and complications. Functional status was evaluated by Epstein criteria and the Japanese Orthopedic Association score 1 d after surgery. The median follow-up time was 58.5 (47, 62) mo.

RESULTS

Patients' median age was 65 (47, 70) y and 58.3% were female. The median surgical duration was 156 min and intraoperative blood loss was 10-30 mL. The Japanese Orthopedic Association score improved significantly from preoperatively to postoperatively (6 [5, 6] to 12.5 [12, 13], P < 0.001). Based on Epstein's criteria, treatment outcomes were excellent in nine cases, good in two cases, and fair in one case. All included patients returned to free movement from the second day after surgery. No severe complications were reported during follow-up.

CONCLUSIONS

Percutaneous posterolateral transforaminal endoscopic surgery under local anesthesia can achieve satisfactory safety and efficacy for treating TOLF. No severe complication was noticed during long-term follow-up.

CDUNeXt: efficient ossification segmentation with large kernel and dual cross gate attention

Ossification of the ligamentum flavum (OLF) is the main causative factor of spinal stenosis, but how to accurately and efficiently identify the ossification region is a clinical pain point and an urgent problem to be solved. Currently, we can only rely on the doctor's subjective experience for identification, with low efficiency and large error. In this study, a deep learning method is introduced for the first time into the diagnosis of ligamentum flavum ossificans, we proposed a lightweight, automatic and efficient method for identifying ossified regions, called CDUNeXt. By designing lightweight module structures, utilizing large-kernel convolutions to extracts the long-distance dependencies of different features of the image, and adopting dual-cross-gate-attention(DCGA) to sequentially capture the channel and spatial dependencies so as to fast and accurate segmentation while maintaining fewer parameters and lower complexity. Experiments show that CDUNeXt achieves the best segmentation performance with an optimal balance of lighter weights and less computational cost compared to existing methods. This work fills the gap in the application of deep learning techniques in the diagnosis of ligamentum flavum ossificans, contributes to the realization of lightweight medical image segmentation networks and lays the foundation for subsequent research.

Treatment of cerebrospinal fluid leakage with prolonged use of subfascial epidural drain and antibiotics in patients of thoracic myelopathy after posterior decompression surgery

Background

Cerebrospinal fluid leakage (CSFL) is a prevalent and vexing complication associated with spine surgery. No standard protocol is available guiding CSFL management, especially for thoracic CSFL. The aim of this study was to retrospectively evaluate the efficacy of prolonged use of subfascial epidural drain and antibiotics to treat CSFL after posterior thoracic decompression surgery.

Methods

Fifty-six patients with an average age of 52.3 years (24-76 years), who underwent thoracic decompression with CSFL (group A) and 65 patients with an average age of 54.9 years (25-80 years) without CSFL (group B) were retrospectively reviewed. Patients in group A had prolonged use of subfascial drainage and antibiotics and patients in group B were treated with conventional methods. The surgical results and rate of wound related complications was compared between the two groups.

Results

The average subfascial drainage time was 7.0 ± 2.7 days (2-16 days) and 3.8 ± 1.4 days (2-7 days) in group A and B, respectively. Higher occupation rate (>49%), presence of dural ossification and higher MRI grade (>2) were more likely to presented with CSFL. In group A, four patients (7.1%) presented with deep wound infection and were successfully managed with wound debridement or intravenous antibiotics. In group B, one patient (1.5%) had a superficial wound infection and was treated with antibiotics. No patients presented with wound dehiscence, wound exudation or CSF fistulation.

Conclusion

The occupation rate of ossified mass and presence of dural ossification were the major risk factors of CSFL. No significant difference in infection rates was observed between the patients in group A and B.

Preoperative Magnetic Resonance Imaging Signal Intensity Classification Is Associated With Clinical Presentation and Surgical Outcomes in Myelopathy Caused by Thoracic Ossification of Ligamentum Flavum: A Multicenter Study

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

To explore whether classification of the increased signal intensity (ISI) on magnetic resonance imaging (MRI) correlates with clinical presentations and outcomes in symptomatic thoracic ossification of ligamentum flavum (T-OLF) patients.

METHODS

All patients with symptomatic T-OLF who underwent laminectomy at four institutions were reviewed. The ISI on preoperative T2-weighted MRI was divided into 3 groups, Grade 0, none; Grade 1, light (obscure); and Grade 2, intense (bright). Neurological function before surgery and at follow-up was evaluated by the revised Japanese Orthopedic Association (JOA) score. Patients' demographics, clinical manifestations, and surgical outcomes were compared.

RESULTS

A total of 94 patients were involved. Preoperative MRI showed 32 patients in Grade 0, 39 patients in Grade 1, and 23 patients in Grade 2. Low extremities numbness, weakness, and clinical signs were less frequent in Grade 0 patients. The grade of ISI was correlated with the duration of symptoms and cord compression. Grade 0 patients had a better preoperative JOA score than those with ISI changes, while Grade 2 patients showed worse neurological recovery, longer duration of operation, more intraoperative blood loss, and a higher incidence of perioperative complications.

CONCLUSION

The classification of ISI is an effective parameter for preoperatively assessing cord compression, clinical severity, and surgical outcomes in T-OLF patients. Grade 0 patients have relatively mild neurological impairment but are more likely to be misdiagnosed. Grade 2 indicates the worst clinical impairment and neurological recovery, and implies a risky and challenging surgery.

Comparison of Surgical Results of the Bridge Crane Technique Versus Laminectomy for the Treatment of Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum

STUDY DESIGN

A retrospective study.

OBJECTIVES

This study aimed to evaluate the safety and effectiveness of the bridge crane technique versus laminectomy for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum (OLF).

METHODS

Totally 41 patients who underwent surgical decompression due to thoracic OLF from May 2017 to June 2018 in our institution were enrolled in this study and were divided into group BG (bridge crane technique, n = 19) and group L (laminoectomy, n = 22). Demographic data was collected from medical records and the modified Japanese Orthopaedic Association (JOA) scoring system was used to evaluate the neurological outcomes during the follow-up. Surgery-related complications were analyzed.

RESULTS

The mean duration of follow-up was comparable between group BG (19.4 ± 1.5 months) and group L (19.6 ± 1.4 months). No statistical differences were observed between two groups in terms of gender, age, duration of symptoms, preoperative occupying rate, involved levels, operation time, intraoperative blood loss, and complications. The JOA score significantly increased at the final follow-up in both groups. However, patients in group BG had higher JOA score and recovery rate (P < 0.05). Four patients in group L experienced complications, including 3 cerebrospinal fluid (CSF) leakage and one postoperative hematoma. Only one patient in group BG had CSF leakage.

CONCLUSION

The results of this study suggested that bridge crane technique may be relatively safe and effective for patients with symptomatic thoracic OLF with more satisfactory clinical improvement. However, high-quality studies are still required to validate the results of this study.

Unilateral biportal endoscopic decompression for symptomatic thoracic ossification of the ligamentum flavum: a case control study

PURPOSE

Thoracic ossification of the ligamentum flavum (OLF) is an uncommon disease that mostly occurs in East Asians. Laminectomy is often considered when patients develop neuro-related symptoms but may associate with treatment-related complications. This study aimed to evaluate the efficacy and safety of unilateral biportal endoscopic (UBE) decompression treatment in patients with symptomatic OLF.

METHODS

From January 2020 to January 2021, patients with spinal cord compression symptoms and imaging-defined single-level thoracic OLF were enrolled in this study and received UBE decompression treatment. Their pre- and postoperative neurological statuses were evaluated by the modified Japanese Orthopaedic Association (mJOA) score, Visual Analog Scale (VAS) for leg pain, and Frankel grade.

RESULTS

Fourteen patients with an average age of 59.4 years were enrolled in the study. The mean operation time was 66.1 ± 15.4 minutes. Patients were followed up for at least one year after receiving the treatment. Our data suggested that their mJOA score (preop 6.2 ± 1.2, 1 year 8.5 ± 0.9; P < 0.001) and VAS score (preop 4.5 ± 2.0, 1 year 0.5 ± 0.9; P < 0.001) were significantly improved compared with that before operation. Cerebrospinal fluid leakage occurred in one patient, head and neck pain occurred in two patients, and hyperalgesia of lower limbs occurred in two patients. All these complications did not cause serious consequences.

CONCLUSION

This primary study indicated that the UBE decompression treatment can achieve satisfactory clinical results in patients with thoracic OLF at single level and provide an alternative treatment option.

Ossified Ligamentum Flavum: Epidemiology, Treatment, and Outcomes

Ossification of the ligamentum flavum (OLF) is an uncommon but potentially serious spinal condition which can cause progressive compression of the spinal canal with associated devastating neurologic compromise. Although debate exists regarding the exact etiology of OLF, overexpression of genes and transcription factors centered around the Notch and Wnt signaling pathways because of increased mechanical stress seems to be related. There are many clinical and radiographic presentations of OLF; however, progressive myelopathy is the most commonly encountered. Radiographic analysis may reveal isolated OLF or OLF combined with ossification of other areas of the spine, such as disk, posterior longitudinal ligament, and dura. When surgery is necessary for OLF, several surgical strategies exist including open laminectomy with excision, endoscopic decompression, Bridge Crane resection, en block resection, and combined anterior and posterior approaches. Resection may be complicated by dural adhesion or dural ossification, and postoperative neurologic deficits are not uncommon.

Clinical Efficacy of Endoscopic-Assisted Resection of Single-Segment Ossification of the Posterior Longitudinal Ligament in the Treatment of Thoracic Spinal Stenosis

Objective

To explore the clinical efficacy, characteristics and safety of endoscopic-assisted resection of single-segment posterior longitudinal ligament ossification in the treatment of thoracic spinal stenosis (TSS).

Method

Fifteen TSS patients, including 6 males and 9 females aged 43–70 years treated with endoscopic-assisted resection of single-segment posterior longitudinal ligament ossification through the transfacet joint approach by our team from November 2016 to June 2020 were retrospectively analyzed. The operation time, intraoperative blood loss, and postoperative complications were recorded. The VAS score, ODI and JOA score (full score, 11 points) were recorded before the operation, after the operation and at the last follow-up to evaluate the clinical efficacy and calculate the improvement rate.

Results

The ventral side of the spinal cord was decompressed in all patients, providing improvements in neurological symptoms and significant pain relief. The mean follow-up time was 20.27 ± 3.87 months. Mean operation time, intraoperative blood loss, and hospitalization time were found to be 84.80 ± 13.23 min, 36.33 ± 7.41 mL, 5.13 ± 1.02 days; respectively.The JOA score at the last follow-up was 8.6 ± 1.25, which was significantly better than the preoperative (5.53 ± 1.20) and postoperative (6.87 ± 1.31) scores (p < 0.05). The mean JOA score improvement rate was 56.5 ± 18.00%. The JOA score improvement rate classification at the last follow-up was excellent in 3 cases, good in 8 cases, effective in 3 cases, and no change in 1 case; for an effective rate of 93.33%. The VAS score significantly decreased from 6.67 ± 1.01 preoperatively to 3.47 ± 0.88 postoperatively and 1.73 ± 0.67 at the last follow-up (p < 0.05). The ODI significantly decreased from 72.07 ± 6.08 preoperatively to 45.93 ± 5.01 postoperatively and 12.53 ± 2.33 at the last follow-up (p < 0.05). Dural rupture occurred in 2 patients during the operation; 1 patient experienced neck discomfort during the operation, which was considered to be caused by high fluid pressure and was relieved by massage and by lowering the height of the irrigation fluid. No cases of cerebrospinal fluid leakage, wound infection or other complications occurred.

Conclusion

Endoscopic-assisted resection of posterior longitudinal ligament ossification through the facet joint approach is a safe and effective method for the treatment of TSS.

The role of cerebrospinal fluid cross-section area ratio in the prediction of dural ossification and clinical outcomes in patients with thoracic ossification of ligamentum flavum

Background

It is imperative to preoperatively distinguish dural ossification (DO) and thus anticipate the risks and outcome of the surgery for patients with ossification of ligamentum flavum (OLF). However, studies have disagreed as to the efficacy of the radiographic signs or factors to predict DO and surgical outcome. In additon, the association between the cerebrospinal fluid cross-section area ratio (CCAR) and DO or clinical outcome had not been reported. The purpose of this study was to analyse CCAR and its role in prediction of DO and neurological function recovery rate in patients with OLF.

Methods

Fifty-two consecutive patients with OLF, who underwent posterior thoracic decompression and fusion between September 2012 and March 2019 at a single institution, were retrospectively reviewed. Demographic data, radiographic signs of DO, CCAR, pre- and postoperative modified Japanese Orthopedic Association (mJOA) score were recorded.

Results

There were 27 patients in the DO group and 25 patients in the non-DO group, with a mean age at surgery of 57.4 years and 53.9 years, respectively. No significant differences were found in sex, age, segment of maximum compression and preoperative mJOA score between the two groups. The receiver operating characteristic curve showed that the value of CCAR had a relatively high value for diagnosis of DO and prediction of neurological function recovery rate (P = .000). According to the value of CCAR, three zones were defined as DO zone (≤14.3%), non-DO zone (≥44.5%), and gray zone (14.3 to 44.5%). When the value of CCAR≤14.3%, the recovery rate was poor or fair, while it had good or excellent recovery when CCAR≥45.2%.

Conclusion

The value of CCAR had a high diagnostic value for prediction of DO and neurological function recovery rate in patients with OLF.

Comparison of Surgical Outcomes Between Staged and Simultaneous Decompression of Discontinuous Thoracic Ossification of the Ligamentum Flavum: A Retrospective Study

BACKGROUND

Discontinuous thoracic ossification of the ligamentum flavum (TOLF) is diagnosed according to the number and distribution of involved segments seen on magnetic resonance images. When TOLF causes thoracic myelopathy, surgical intervention for these lesions becomes unavoidable. However, there are few reports on the outcomes of surgery for discontinuous TOLF.

METHODS

The study included 26 patients of mean age 55.0 years who underwent simultaneous (n = 16) or staged (n = 10) decompression of discontinuous TOLF between July 2006 and June 2016. Final neurologic status was evaluated using the modified Japanese Orthopaedic Association (JOA) score. The surgical data and incidence of complications were compared. The mean follow-up duration was 73.3 months.

RESULTS

There was no between-group difference in number of levels decompressed or the amount of intraoperative blood loss. There was a significant improvement in the JOA score from 4.0 before surgery to 8.0 postoperatively, with an average recovery rate of 58.3%. The JOA recovery rate was significantly better in the staged group than simultaneous group (68.4% vs. 52.0%, P < 0.05). However, the incidence of complications was similar between the staged and simultaneous groups including for dural tear (1 vs. 6, P = 0.19), cerebrospinal fluid leak (4 vs. 6, P = 1.00), and transient neurologic deterioration (0 vs. 2, P = 0.51).

CONCLUSIONS

The surgical outcome of staged decompression for discontinuous TOLF seems to be better than that of simultaneous decompression. The complication rates of these 2 strategies are similar.

Thoracic ligamentum flavum ossification: a rare cause of spinal cord injury without tomographic evidence of trauma in a Caucasian patient. Case report and literature review

INTRODUCTION

Acute spinal cord injury without tomographic evidence of vertebral fracture or dislocation in patients post trauma can represent a diagnostic challenge for the treating physician. The ossification of thoracic ligamentum flavum has been widely published as a cause of thoracic myelopathy, however its association with acute traumatic spinal cord injury is limited to isolated cases.

CASE PRESENTATION

we report a Caucasian 37-year-old man who suffered a high-energy thoracolumbar spine trauma in a motorcycle accident with acute paraplegia. He presented ossification of the ligamentum flavum between the thoracic vertebrae T10 and T11 with a decrease in the diameter of the vertebral canal as the only pathological finding. We treated the patient with early surgical release before 72 h of trauma. We performed a posterior approach with hemilaminectomy and T10-T11 flavectomy. Arthrodesis was done with T10-T11 pedicle screws. Postoperative neurological status improved from ASIA Impairment Scale (AIS) A to C with severe functional dependence.

DISCUSSION

Ossification of the ligamentum flavum should be considered in the differential diagnosis in patients presenting with acute traumatic spinal cord injury without tomographic evidence of trauma. A proper diagnosis in time is the key to decision making and treatment of spinal cord injury. Especially in adult patients, we must consider nontraumatic associated factors that could be involved in the spinal cord injury mechanism, such as ossification of the ligamentum flavum.

The clinical value of three-dimensional measurement in the diagnosis of thoracic myelopathy caused by ossification of the ligamentum flavum

Background

Thoracic ossification of the ligamentum flavum (OLF) is a major cause of thoracic myelopathy, which is often accompanied by multiple segmental stenosis or other degenerative spinal diseases. However, in the above situations, it is difficult to determine the exact segment responsible. The objective of this study was to analyze three-dimensional (3D) radiological parameters in order to establish a novel diagnostic method for discriminating the responsible segment in OLF-induced thoracic myelopathy, and to evaluate its superiority compared to the conventional diagnostic methods.

Methods

Eighty-one patients who underwent surgery for thoracic myelopathy caused by OLF from 2016 to 2020 were enrolled in this study as the myelopathy group, and 79 patients who had thoracic OLF but displayed no definite neurological signs from 2018 to 2020 were enrolled as the non-myelopathy group. We measured the one-dimensional (1D), two-dimensional (2D), and 3D radiological parameters, calculated their optimal cutoff values, and compared their diagnostic values.

Results

Significant differences were observed in the 1D, 2D, and 3D radiological parameters between the myelopathy and non-myelopathy groups (P<0.01). As a 3D radiological parameter, the OLF volume (OLFV) ratio (OLFV ratio = OLFV/normal canal volume × 100%) was the most accurate parameter for diagnosing OLF-induced thoracic myelopathy, with a diagnostic coincidence rate of 88.1%. We also found that an OLFV ratio of 26.3% could be used as the optimal cutoff value, with a sensitivity of 87.7% and a specificity of 88.6%. Moreover, the OLFV ratio [area under the curve (AUC): 0.92, 95% confidence interval (CI): 0.86-0.95] showed a statistically higher diagnostic value than the 1D and 2D parameters (AUC: 0.75, 95% CI: 0.67-0.81; AUC: 0.84, 95% CI: 0.77-0.89, respectively) (P<0.05). Pearson correlation analysis illustrated that the OLFV ratio was significantly negatively correlated with preoperative modified Japanese Orthopedic Association (mJOA) score (r=-0.73, 95% CI: -0.81 to -0.60, P<0.01).

Conclusions

Our results demonstrate the superiority of the OLFV ratio over the conventional 1D and 2D computed tomography (CT)-based radiological parameters for the diagnosis of OLF-induced thoracic myelopathy. The novel diagnostic method based on the OLFV ratio will help to determine the responsible segment in multi-segmental thoracic OLF or when thoracic OLF coexists with other degenerative spinal diseases. The OLFV ratio also accurately reflects the clinical state of symptomatic patients with thoracic OLF.

Ossification of the ligamentum flavum in the thoracic spine mimicking sciatica in a young baseball pitcher:a case report

Thoracic ossification of the ligamentum flavum (OLF) is a pathological condition that causes myelopathy, with unilateral lower extremity pain rarely a feature in the presenting complaint. Moreover, most symptomatic cases of thoracic OLF occur in middle-aged men, with younger individuals rarely affected.　We present a rare case of severe and chronic unilateral buttock and leg pain mimicking sciatica due to thoracic OLF in a professional baseball pitcher. A 28-year-old, right-handed, Japanese professional baseball pitcher experienced intractable left leg pain with numbness and spasticity. After the initial presentation, extensive testing focusing on lumbar, hip, and pelvis lesions failed to identify a cause for the pain. One year after onset, careful neurological examination showed signs of upper motor neuron disturbance, and thoracic computed tomography and magnetic resonance imaging revealed thoracic OLF at the level of the thoracolumbar junction. After resection of the thoracic OLF, the pain, numbness, and spasticity completely resolved. He resumed full training and was pitching in top condition within four months after surgery. Though rare, thoracic OLF should be considered in the differential diagnosis of lower extremity pain in young athletes, especially amongst high-level baseball pitchers.

Surgical results and prognostic factors following percutaneous full endoscopic posterior decompression for thoracic myelopathy caused by ossification of the ligamentum flavum

Minimally invasive surgery (MIS) has shown satisfactory surgical results for the treatment of thoracic myelopathy (TM) caused by ossification of the ligamentum flavum (OLF). This study investigated the prognostic factors following MIS and was based on the retrospective analysis of OLF patients who underwent percutaneous full endoscopic posterior decompression (PEPD). Thirty single-segment OLF patients with an average age of 60.4 years were treated with PEPD under local anaesthesia. Clinical data were collected from the medical and operative records. The surgical results were assessed by the recovery rate (RR) calculated from the modified Japanese Orthopaedic Association (mJOA) score. Correlations between the RR and various factors were analysed. Patients’ neurological status improved from a preoperative mJOA score of 6.0 ± 1.3 to a postoperative mJOA score of 8.5 ± 2.0 (P < 0.001) at an average follow-up of 21.3 months. The average RR was 53.8%. Dural tears in two patients (6.7%, 2/30) were the only observed complications. Multiple linear regression analysis showed that a longer duration of preoperative symptoms and the presence of a high intramedullary signal on T2-weighted MRI (T2HIS) were significantly associated with poor surgical results. PEPD is feasible for the treatment of TM patients with a particular type of OLF. Patients without T2HIS could achieve a good recovery if they received PEPD early.

The Relationship Between Dural Ossification and Spinal Stenosis in Thoracic Ossification of the Ligamentum Flavum

BACKGROUND

Dural ossification represents a difficult problem in the surgical management of thoracic ossification of the ligamentum flavum. Few studies have focused on this condition because of the relatively low prevalence. We speculated that dural ossification occurs only when spinal stenosis of patients with thoracic ossification of the ligamentum flavum progresses. Herein, we aimed to determine the relationship between dural ossification and spinal stenosis in thoracic ossification of the ligamentum flavum.

METHODS

In this study, 123 consecutive patients with ossification of the ligamentum flavum were retrospectively analyzed. Sixty-seven patients were ultimately included and were divided into a group that had dural ossification and a group that did not have dural ossification. Patient characteristics and radiographic data were recorded. The cross-sectional area occupying ratio ([1 - cross-sectional area of the narrowest level/normal cross-sectional area] × 100%) was measured and was calculated by 3 independent observers, followed by statistical analysis.

RESULTS

The 2 groups were comparable with respect to sex, age, body mass index, and distribution of the segment with maximum compression. The mean cross-sectional area occupying ratio (and standard deviation) in the T9-T12 subgroup in the group with dural ossification (63.4% ± 8.6%) was significantly higher (p < 0.001) than that in the group without dural ossification (30.7% ± 10.4%). The overall interobserver reliability for measurements of the cross-sectional area occupying ratio (interclass correlation coefficient, 0.976) was excellent. Thus, the cross-sectional area occupying ratio could be used as an indicator to distinguish between patients with ossification of the ligamentum flavum who did and did not have dural ossification, with a high diagnostic value, in the T9-T12 subgroup. A cross-sectional area occupying ratio of >55% (sensitivity of 81.5% and specificity of 100%), the "ossification zone," was indicative of dural ossification in patients with ossification of the ligamentum flavum, whereas a value of <45% (sensitivity of 100% and specificity of 89.7%) was considered safe. Moreover, ratios between 45% and 55% were considered to be in the "gray zone."

CONCLUSIONS

The results of this study indicate that the severity of spinal stenosis was significantly associated with dural ossification in ossification of the ligamentum flavum and the cross-sectional area occupying ratio may be used as an indicator of dural ossification in the lower thoracic spine.

CLINICAL RELEVANCE

The diagnosis of dural ossification was based on the intraoperative evidence, and the results could help spine surgeons to prepare for the surgical procedure.

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.

Clinically significant radiographic parameter for thoracic myelopathy caused by ossification of the ligamentum flavum

PURPOSE

To investigate radiographic parameters to improve the accuracy of radiologic diagnosis for ossification of ligamentum flavum (OLF)-induced thoracic myelopathy and thereby establish a useful diagnostic method for identifying the responsible segment.

METHODS

We classified 101 patients who underwent surgical treatment for OLF-induced thoracic myelopathy as the myelopathy group and 102 patients who had incidental OLF and were hospitalized with compression fracture as the non-myelopathy group between January 2009 and December 2016. We measured the thickness of OLF (TOLF), cross-sectional area of OLF (AOLF), anteroposterior canal diameter, and the ratio of each of these parameters.

RESULTS

Most OLF cases with lateral-type axial morphology were in the non-myelopathy group and most with fused and tuberous type in the myelopathy group. Most grade-I and grade-II cases were also in the non-myelopathy group, whereas grade-IV cases were mostly observed in the myelopathy group. The AOLF ratio was found to be the best radiologic parameter. The optimal cutoff point of the AOLF ratio was 33.00%, with 87.1% sensitivity and 87.3% specificity. The AOLF ratio was significantly correlated with preoperative neurological status.

CONCLUSIONS

An AOLF ratio greater than 33% is the most accurate diagnostic indicator of OLF-induced thoracic myelopathy. In cases of multiple-segment OLF, confirmation of cord signal change on MRI and an AOLF measurement will help determine the responsible segment. AOLF measurement will also improve the accuracy of diagnosis of OLF-induced thoracic myelopathy in cases of grade III or extended-type axial morphology. These slides can be retrieved under Electronic Supplementary Material.

Ossification of the Ligamentum Flavum in a Nineteenth-Century Skeletal Population Sample from Ireland: Using Bioarchaeology to Reveal a Neglected Spine Pathology

Ossification of the ligamentum flavum of the spine (OLF) is rarely reported in individuals of European ancestry. It has, however, been observed in archaeological skeletons from Europe. The aim of this study was to revisit OLF rates, utilising a mid-nineteenth-century skeletal sample from Ireland. The hypothesis was that the OLF prevalence rate was similar to studies on non-Europeans. Spines from 345 individuals were analysed, and the extent of OLF recorded on the cranial and caudal attachment sites of each vertebra using the following classification system: Grade 0 (no change); Grade 1 (<2 mm); Grade 2 (2–4 mm); Grade 3 (≥4 mm). OLF was observed at prevalence rates of 83.6%. There was no disparity in prevalence based on sex, except for individuals aged 36–45 years at death in which the male rate was higher. Advancing age was a determining factor in the OLF occurrence with an onset in young adulthood (18–25 years), and most severe grades occurring over the age of 25 years. OLF coincides with spinal osteoarthritis, spondylosis deformans and Schmorl’s nodes in both sexes, and with intervertebral osteochondrosis in females. The results of this study indicate that OLF is likely to be an understudied rather than rare condition in European populations.

Evaluation of Measuring Methods of Spinal Canal Occupation Rate in Thoracic Ossification of Ligamentum Flavum

OBJECTIVE

The degree of hypertrophy of thoracic ossification of ligamentum flavum (TOLF) is related to the severity of the myelopathy. There is no uniform measuring method to calculate the spinal canal occupation ratio (COR) of TOLF simply and effectively. The study was to determine an appropriate measuring method to calculate the COR of TOLF.

METHODS

A total of 37 computed tomography cross-sectional imaging scans (bone window) from 22 patients were analyzed retrospectively in this study. The ventral side of the lamina or superior facet was selected as bottom in Method 1, and a line perpendicular to the anteroposterior diameter and on the dorsal side of the spinal canal was selected as bottom in Method 2. The maximum thickness of the bilateral ossified mass to the bottom is d1 and d2. The maximum distance from the anterior wall of the spinal canal to the bottom is d. COR of Method 1 or 2 was (d1 + d2)/2d × 100%. Standard COR values calculated by software served as controls.

RESULTS

The standard COR values were <50% in 10 images, 51%-60% in 9 images, 61%-70% in 10 images, and >71% in 8 images. There was no significant difference between COR1 and COR in every range. There were significant differences between COR2 and COR in the ≤50%, 51%-60%, and 61%-70% groups but they were not statistically significant in the >70% group.

CONCLUSIONS

Method 1 is a convenient and practical method to measure the COR of ossification in patients with TOLF.