Thoracic spinal cord injury without major bone injury associated with ossification of the ligamentum flavum

Clinical progression of ossification of the ligamentum flavum in thoracic spine: a 10- to 11-year follow-up study

BACKGROUND

Thoracic ossification of ligamentum flavum (TOLF) can be asymptomatic and progress insidiously. But, long-term follow-up results of clinical progression of TOLF are still unknown.

METHODS

The clinical progression of 81 patients with TOLF at our center, followed for 10 to 11 (mean, 10.3) years from May 2010 to November 2021, were analyzed. Among them, 51 patients with thoracic myelopathy were caused by single- or multi-segment TOLF, and received partial TOLF resection (30 patients) or total TOLF resection (21 patients). The remaining 30 patients showed TOLF on imaging examinations, but TOLF was not the responsible compressing factor causing myelopathy and with no TOLF resection. The mJOA score (total 11 scores) and spinal operation were used to evaluate the clinical progression at follow-up.

RESULTS

During the 10- to 11-year follow-up of 81 TOLF patients, 71 (87.7%) had no deterioration of neurological function, and 10 (12.3%) patients had deterioration of neurological function and had another spinal operation, including only 4 (4.9%) suffered thoracic myelopathy caused by the progression of TOLF; 6 (7.4%) for other spinal diseases: 2 (2.5%) had fall damage and acute spinal cord injury at the TOLF level; 2 (2.5%) had thoracic myelopathy caused by ossification of posterior longitudinal ligament (OPLL); 2 (2.5%) had cervical spondylosis and received cervical operation.

CONCLUSIONS

Most TOLF (87.7%) patients had no clinical progression and received no reoperations for TOLF in the ten-year dimension (mean, 10.3 years). Narrow spinal canal for TOLF increases the risk of traumatic paraplegia.

Cyclic Tensile Stress to Rat Thoracolumbar Ligamentum Flavum Inducing the Ossification of Ligamentum Flavum: An In Vivo Experimental Study

STUDY DESIGN

Western blot, reverse transcription-polymerase chain reaction (RT-PCR), radiological, and histological analyses of the rat ossification of ligamentum flavum (OLF) induced by cyclic tensile stress.

OBJECTIVE

The aim of this study was to induce the OLF using cyclic tensile stress to rat thoracolumbar ligamentum flavum, and to investigate the possible molecular mechanism of tension-induced OLF.

SUMMARY OF BACKGROUND DATA

Tensile stress has been considered as an important factor leading to the OLF. So far, however, no OLF induced by tension has been reported.

METHODS

Forty rats were randomly divided into five equal groups. For control groups, the blank and anesthesia groups were not subjected to tension. For experimental groups, the 4-, 8-, and 12-week groups were subjected to cyclic tensile stress of ligamentum flavum after abdominal anesthesia for 4 weeks, 8 weeks, and 12 weeks, respectively, using an original stress apparatus for rats. The radiological and morphological changes of rat spine, as well as the protein and mRNA expressions of CD44, bone morphogenetic protein-2 (BMP-2), integrin β3, collagen protein type I (COL1), osteopontin (OPN), runt-related transcription factor 2 (RUNX-2), and vascular endothelial growth factor (VEGF), were concerned.

RESULTS

The micro-CT showed OLF in the 4-, 8-, and 12-week group. The axial maximum occupied area of ossifications was 1.42 mm2, 3.35 mm2, and 7.28 mm2, respectively. In histopathology, chondrocytes proliferated in the experimental model; woven bone arose in the 8- and 12-week groups, and was more noticeable in the 12-week group. According to western blot and RT-PCR, the expressions of seven osteogenesis-related molecules were all increased in three experimental groups.

CONCLUSION

Cyclic tensile stress to the ligamentum flavum in rats can induce the OLF, and the longer the duration, the more visible the osteogenesis. The upregulation and synergism of osteogenesis-related molecules may contribute to the OLF induced by tensile stress.Level of Evidence: N/A.

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.

Dynamic changes in longitudinal stretching of the spinal cord in thoracic spine: Focus on the spinal cord occupation rate of dural sac

OBJECTIVES

This study aimed to evaluate the anteroposterior diameters and cross-sectional areas of the dural sac and spinal cord in the thoracic spine, to elucidate the spinal cord occupation rate of the dural sac in these dynamic changes for each level using multidetector-row computed tomography (MDCT).

PATIENTS AND METHODS

Fifty patients with cervical or lumbar spinal disease were prospectively enrolled. After preoperative myelography, MDCT was performed at maximum passive flexion and extension. The anteroposterior diameter and cross-sectional area of the dural sac and spinal cord in the axial plane and the thoracic spinal cord length in the sagittal plane were measured. The spinal cord occupation rate in the dural sac was calculated.

RESULTS

The spinal cord occupation rate of the dural sac in anteroposterior diameter was lower on flexion than on extension, with significant differences from the T1/T2 to T11/T12 levels (p < 0.0001). The spinal cord occupation rate of the dural sac in cross-sectional area was lower on flexion than on extension, with significant differences except from T3/T4 to T6/T7 levels (p < 0.01). There was a bimodal increase in the occupation rate with elevations at the cervicothoracic junction and thoracolumbar junction. The thoracic spinal cord length on flexion was significantly longer than that on extension (p < 0.0001).

CONCLUSIONS

The spinal cord occupation rate of the dural sac was lower on flexion than on extension, despite thoracic spine being considered a rigid region. The dynamic changes in longitudinal stretching and shrinkage of the spinal cord affected the occupation rate.