Focal anterior displacement of the thoracic spinal cord without evidence of spinal cord herniation or an intradural mass

Abstract

Objective: We report magnetic resonance imaging (MRI) findings on focal anterior displacement of the thoracic spinal cord in asymptomatic patients without a spinal cord herniation or intradural mass.

Materials and methods: We identified 12 patients (male:female = 6:6; mean age, 51.7; range, 15-83 years) between 2007 and 2011, with focal anterior displacement of the spinal cord and without evidence of an intradural mass or spinal cord herniation. Two radiologists retrospectively reviewed the MRI findings in consensus.

Results: An asymmetric spinal cord deformity with a focal dented appearance was seen on the posterior surface of the spinal cord in all patients, and it involved a length of 1 or 2 vertebral segments in the upper thoracic spine (thoracic vertebrae 1-6). Moreover, a focal widening of the posterior subarachnoid space was also observed in all cases. None of the patients had myelopathy symptoms, and they showed no focal T2-hyperintensity in the spinal cord with the exception of one patient. In addition, cerebrospinal fluid (CSF) flow artifacts were seen in the posterior subarachnoid space of the affected spinal cord level. Computed tomography myelography revealed preserved CSF flow in the two available patients.

Conclusion: Focal anterior spinal cord indentation can be found in the upper thoracic level of asymptomatic patients without a spinal cord herniation or intradural mass.

Keywords: MRI; Spinal cord deformity; Thoracic spine.

Fig. 1

Whole-spine sagittal T2-weighted images show incidental findings of focal anterior displacement of thoracic spinal cord in two patients. A, B. Asymmetric dented appearance with ventral angulation of cord and widening of dorsal cerebrospinal fluid (CSF) space are present without intradural mass or spinal cord herniation in upper thoracic spine. Prominent CSF flow artifacts are present in posterior subarachnoid space at involved spine level. Arrow indicates spinal cord.

Fig. 2

Cervical spine magnetic resonance imaging (A-D) and additional computed tomography (CT) myelography (E, F) of 38-year-old woman who presented with neck pain. Sagittal T2-weighted image (A) and axial T2-weighted image (B) show anteriorly displaced spinal cord at T2/3 level with hypointense elongated flow artifact in extended dorsal space at same level. Sagittal (C) and axial (D) CT myelography in supine position show widening of posterior space without intradural filling defect or blockade (such as those caused by arachnoid cyst). Sagittal (E) and axial (F) CT myelography in prone position show preservation of anterior subarachnoid space and intact cerebrospinal fluid flow. There was no finding of spinal cord herniation or spinal cord adhesion. All axial images (B, D, F) were obtained at T2 level. Arrow indicates spinal cord.

Fig. 3

Lumbosacral spine magnetic resonance imaging (MRI) of 48-year-old woman who presented with low back pain. A. Sagittal T2-weighted image shows asymmetric dented appearance and anteriorly displaced spinal cord at T4 level. B, C. Follow-up cervical spine MRI study 4 months after first examination. Sagittal T2-weighted image (B) shows no interval change in cord deformity. Axial T2-weighted image (C) shows ventral displacement of cord without focal spinal cord herniation and relatively preserved anterior subarachnoid space at T4 level. Arrow indicates spinal cord.