Risk factors and outcomes in thoracic stenosis with myelopathy: A single center experience

Fibrotic and inflammatory characteristics of epidural fat adjacent to the ossification area in patients with ossification of the ligament flavum

Objectives

To observe histological and inflammatory characteristics of epidural fat (EF) adjacent to the ossification area in patients with ossification of the thoracic ligament flavum (TOLF) and provide a preliminary research basis for investigating the impact of the EF on OLF.

Methods

Samples of EF and autologous subcutaneous adipose tissue (SCAT) from TOLF patients (n = 26) and non-TOLF patients (n = 23) were harvested during posterior thoracic spine surgery. Adipocyte size and fibrosis were measured by histology. Vascularization and inflammatory cell infiltration were evaluated by immunohistochemical staining. Adipogenesis-related genes were assessed by real-time quantitative PCR. Conditioned media from cultured EF were evaluated via enzyme-linked immunosorbent assay to detect the secretion of inflammatory cytokines, including interleukin-6 (IL-6), tumor necrosis factor (TNF-α), and leptin. The phosphorylated STAT3 protein level in ligament flavum (LF) was examined using Western blot.

Results

Adipocytes size in EF was similar between in the TOLF and non-TOLF groups, but significantly smaller than that from autologous SCAT. Adipogenesis-related mRNA expression in EF was lower than that in SCAT. More fibrosis and vascularization were found in TOLF than in non-TOLF. EF in the TOLF group exhibited more macrophages and B lymphocytes infiltrated. The levels of cytokines such as IL-6, TNF-α, and leptin secreted by EF were significantly higher in the TOLF group than non-TOLF. The level of phosphorylated STAT3 in LF was significantly upregulated in the TOLF group.

Conclusions

Morphologically, EF adjacent to the ossification area is smaller and more uniform than autologous SCAT, exhibiting a characteristic similarity to visceral fat. EF in the TOLF group shows a more fibrotic, vascularized, and inflammatory phenotype, which secretes multiple cytokines. The phosphorylated STAT3 protein was significantly upregulated in the TOLF group. Whether these properties of EF directly affect the process of OLF needs to be further explored.

The Natural History of Ossification of Yellow Ligament of the Thoracic Spine on MRI: A Population-Based Cohort Study

PURPOSE

To assess the natural history of ossification of yellow ligament (OYL) in the thoracic spine and determine risk factors for progression based on a longitudinal population-based cohort.

METHODS

A prospective, longitudinal cohort study was performed on a population-based cohort of Southern Chinese volunteers. T2-weighted magnetic resonance imaging (MRI) was used at baseline to identify any OYL and was verified with computed tomography. Follow-up MRI was performed 5 years later. Parameters under study included the size of OYL, levels of involvement, morphology (round, triangular, beak), whether it crossed the midline and any disc degeneration.

RESULTS

A total of 114 (6.1%) individuals were identified to have OYL at baseline out of the 1864 individuals. Size progression occurred predominantly at the lower thoracic region. Majority of the new OYL were also in the lower thoracic spine and was associated with higher body mass index (BMI). Smokers were associated with OYL size progression while patients with higher BMI tended to develop new OYL at follow-up. Progression commonly occurred at the lower thoracic levels and regression occurred mostly at the upper thoracic levels.

CONCLUSIONS

This is the first population-based series addressing the natural history of OYL. Better understanding of the natural history of OYL may provide incentive to introduce preventive measures such as weight reduction and close monitoring for myelopathy development in those at-risk groups for progression. This is especially important for patients with lower thoracic OYL and who are smokers with higher BMI.

LEVEL OF EVIDENCE

1 (prognostic study).

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.

Is T9-11 the true thoracolumbar transition zone?

OBJECTIVE

Degenerative thoracic stenosis has been shown to most frequently involve the lower thoracic segments (T9-T12) where there is greater mobility and vulnerability due to flexion, extension and rotation of the spine. The thoracolumbar junction is considered anatomically to be T12-L1; the anatomical transition between the relatively immobile thoracic spine and relatively mobile lumbar spine. From anecdotal experience at our institution, we hypothesise that the true thoracolumbar junction is higher, at T10-11; the point of transition from floating to false ribs resulting in increased mobility at T10-11.

METHODS AND MATERIALS

A retrospective review was performed of MRI lumbar and whole spine performed on patients aged 10-40 years in our institution over a 5-year period. Patients with previous surgery, chronic spinal disorders and congenital abnormalities were excluded from the study. Intervertebral discs from T8-9 to L1-2 were assessed for evidence of degeneration using the Pfirrmann grading system. Data obtained from a study using computer-based models to assess mean resultant loads in flexion, sitting and standing from T8-9 to L1-2 on patients aged 18-35 years was also analysed. The mean load gradients between two consecutive discs from T8 to L2 were analysed. Statistical analysis was performed with SPSS (p < 0.05 was considered statistically significant).

RESULTS

Three-hundred and twenty-two MRI studies were reviewed. Mean Pfirrmann grade was highest at T8-9 and T9-10 (1.35 ± 0.99 and 1.32 ± 0.93 respectively).Pfirrmann grade differed significantly at each level (χ² = 45.137 p = 0.001). Difference in mean load gradient from T9 to T11 was significantly higher than mean load gradient across T11 to L1 in both sitting and standing (0.095 ± 0.062 vs 0.050 ± 0.044 kN; p = 0.007, and 0.101 ± 0.061 kN vs 0.040 ± 0.054 kN; p = 0.007).

CONCLUSION

The changes in segmental loads and more severe disc degeneration at T9-11 compared to T11-L1 support our hypothesis that the true thoracolumbar transition is higher than expected, at T10-11; where the rib cage transitions from floating to false ribs.

Transforaminal en bloc resection for the treatment of thoracic ossification of the ligamentum flavum: Retrospective cohort study

BACKGROUND

Our purpose is to introduce transforaminal en bloc resection for the treatment of thoracic ossification of ligamentum flavum, and report outcomes of the procedure.

PATIENTS AND METHODS

The record of patients with symptomatic thoracic ossification of the ligamentum flavum who received transforaminal en block resection from October 2010 to September 2014 were retrospectively reviewed. Outcomes were Japanese Orthopaedic Association (JOA) lower extremity motor dysfunction and sphincter dysfunction scores.

RESULTS

Seventeen patients (10 males, 7 females) with a median age of 60 years were included in the analysis. Surgery was performed as planned without complications in all patients. One segment decompression was performed in 1 case, 2 segment in 9 cases, 3 segment in 3 cases, and 4 segment in 4 cases. The median lower extremity motor dysfunction score was significantly higher at 2 weeks, 3 months, and 6 months postoperatively, and the end of follow-up, than before surgery (median score: 2, 2, 3, 3, respective, vs. 1, all, p ≤ 0.008). There were no significant differences in JOA sphincter dysfunction score between the different time points.

CONCLUSION

Transforaminal en bloc resection is a safe and effective method for the treatment of thoracic ossification of the ligamentum flavum.

The incidence and risk factors of postoperative neurological deterioration after posterior decompression with or without instrumented fusion for thoracic myelopathy

The aim of this study was to explore the incidence and risk factors of postoperative neurological deterioration after posterior decompression with or without instrumented fusion for thoracic myelopathy, and hope to provide references in decision-making and surgical planning for both spinal surgeon and thoracic stenosis patients.By retrieving the medical records from January 2001 to November 2015, 168 patients were retrospectively reviewed. According to the occurrence of postoperative neurological deterioration, patients were divided into 2 groups: neurological deterioration (ND) group and non-ND group. To investigate risk values for the occurrence of ND, 3 categorized factors were analyzed statistically: patient characteristics-preoperative data of age, sex, body mass index, bone mineral density, the duration of disease (from first symptoms to operation), the preoperative neurological function (Frankel grade), and diagnosis; surgical variables-surgery time, the amount of bleeding, mean arterial pressure, intervertebral fusion or not, and instrumentation or not; radiographic parameters-the spinal canal occupancy ratio, location of the lesion, thoracic kyphosis, and kyphosis correction.Postoperative neurological deterioration was developed in 23 of 168 patients (13.7%), and were enrolled as ND group. There was no statistically significant difference between the 2 groups in age at operation, sex composition, body mass index, and bone mineral density. The preoperative diagnosis presented significant difference between the 2 groups, because ossification of posterior longitudinal ligament combined with ossification of the ligamentum flavum was more common in ND group, whereas ossification of the ligamentum flavum alone was more common in non-ND group. There was no difference between the 2 groups in mean surgery time, the incidence of intraoperative direct trauma, and the number of patients that received instrumentation. The mean bleeding was much more in ND group than that in non-ND group, and the mean arterial pressure was lower in ND group than that in non-ND group. Also, the mean spinal canal occupancy ratio was more severe in ND group than that in non-ND group. There were no statistically significant difference between the 2 groups in stenosis location and preoperative thoracic kyphosis. The mean kyphosis correction was more significant in ND group. When included in a multivariate logistic regression model, thoracic disc herniation + ossification of posterior longitudinal ligament, spinal canal occupancy ratio more than 70%, bleeding more than 800 mL, and mean arterial pressure less than 81 mm Hg were independently associated with the postoperative neurological deterioration.In conclusion, ossification of posterior longitudinal ligament combined with ossification of the ligamentum flavum, spinal canal occupancy ratio more than 70%, intraoperative bleeding more than 800 mL, and mean arterial pressure less than 81 mm Hg are risk factors for the occurrence of postoperative neurologic deterioration. Improving surgical technique, shortening operation time, and paying more attention to hemostasis could provide opportunities to reduce the incidence of neurologic deterioration and to improve therapeutic outcomes.