Dynamic MRI Reveals Soft-Tissue Compression Causing Progressive Myelopathy in Postlaminectomy Patients: A Report of Three Cases.

Abstract

Cervical spondylotic myelopathy has been reported as the most common cause of spinal cord dysfunction in individuals older than age fifty-five, although the rate of occurrence is blurred by the difficulty of making a precise and timely diagnosis. The symptoms that patients present with can be inconsistent and show high variability from patient to patient1-4. Magnetic resonance imaging (MRI) has been a beneficial tool for evaluating anteroposterior sagittal diameter, the compression ratio, and the canal-occupying ratio5,6. According to numerous biomechanical and cadaveric studies, cervical flexion results in tension forces on the spinal cord and can cause ventral spinal cord compression against osteophytes and discs. In neck extension, the cervical cord shortens, and there is an increase in the cross-sectional area of the anteroposterior diameter of the spinal cord. In addition, the space available to the spinal cord is reduced as the ligamentum flavum folds inward7,8. We report three cases of progressive myelopathy. The first patient had undergone a previous multilevel cervical laminectomy. Although an initial MRI with the neck in the neutral position showed no spinal cord compression, the patient subsequently underwent dynamic MRI with the neck in extension, which revealed flattening of the spinal cord by soft tissues buckling into the laminectomy defect. The second patient had undergone a previous cervical laminectomy and arthrodesis with lateral mass internal fixation. He presented with progressive myelopathy and exhibited cord flattening on extension MRI, similar to that seen in the first patient. The third patient presented with myelopathic symptoms, had undergone a prior multilevel laminectomy, and had been followed for a syrinx; a cervical MRI with the neck in extension revealed severe stenosis. All three patients were informed that data concerning their cases would be submitted for publication, and they …