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

Jingtao Zhang,Peng Yang,Jie Li,Linfeng Wang,Yong Shen

doi:10.1038/srep23019

Abstract

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.

Highlights

The normal spinal cord signal intensity values on sagittal T2-weighted imaging (WI) were obtained at C7-T1 disc level, and the regions of interest (ROIs) were taken by 0.3 cm[2]
Fifty-six patients had good surgical outcomes, with recovery rates greater than or equal to 50%, while 40 patients had poor surgical outcomes with recovery rates less than 50%
The ISI of the spinal cord on T2-WI is often observed in patients with thoracic OLF, and various authors have speculated on its histopathologic significance and impact on surgical outcome

Summary

Methods

This retrospective study included data of patients who underwent surgery for thoracic myelopathy secondary to OLF at the Department of Spinal Surgery, the Third Hospital of Hebei Medical University in China, between January 1997 and December 2012. The preoperative and postoperative neurological function at 2 years of follow-up was assessed using a modified Japanese Orthopaedic Association (JOA) scoring system (Table 1). The high-signal intensity values of the spinal cord on sagittal T2-WIs were obtained, and the regions of interest (ROIs) were taken by 0.05 cm[2]. The normal spinal cord signal intensity values on sagittal T2-WIs were obtained at C7-T1 disc level, and the ROIs were taken by 0.3 cm[2]. All analyses were performed using SPSS software (version 21.0; SPSS Inc., Chicago, IL, USA)

Results

Discussion

Conclusions