| Objective: Cervical spondylotic myelopathy (CSM) is a common spinal disease, the main pathological mechanism of which was chronic spinal cord compression that resulted in spinal cord degeneration and a series of clinical syndromes, which often occurs in people aged 40-60 years. Some patients may have history of trauma. Spinal cord can be compressed ventrally by the nucleus pulposus, vertebral osteophytes, hypertrophic ligamentum flavum or dorsally by the ossified posterior longitudinal ligament, which mainly leads to numbness and weakness of limbs, unsteady gait, and paresthesia, even paraplegia, bowel and bladder dysfunction in some severe cases. Some of the patients with CSM need surgical treatment, and the outcone is associated with many preoperative factors. MRI is a widely-recognized tool that is one of the most valuable diagnostic methods for the diagnosis of CSM. local or wider area of increased signal intensity (ISI) often can be found on the MRI T2-weighted image in patients with CSM. In recent years, the relationship between ISI on MRI T2-weighted image and surgical outcome has been reported in many studies, but the relationship between ISI on MRI T2-weighted image and poor outcome after surgical treatment remains controversial. The objective of this study was to further investigate whether ISI can help assess the prognosis in patients with CSM by means of measuring the ratio of signal intensity on the basis of preliminary studies.Methods: The participants in this study were 57 patients who underwent posterior cervical decompression for multi-level CSM. There were 34 men and 23 women (mean age, 53.5 years; range, 42-73 years). The symptom duration of these patients ranged from 5 to 41 months; with a mean symptom duration of 20.9 months. Spinal cord was compressed at C3-C6 in 31 patients, and at C4-C7 in 19 patientsat, C3-C7 in 7 patients. Cervical laminectomy was performed in 22 patients, and cervical open-door laminoplasty was performed in 35 patients. Both groups were treated from C3 to C7. All patients underwent high-resolution MRI with a 1.5-Tesla Siemens MAGNETOM Symphony (Siemens, Berlin, Germany) imager before surgery. Sagittal T1-weighted and T2-weighted images of the cervical cord were obtained using a spin echo sequence system for T1-weighted MRI and a fast spin echo sequence system for T2-weighted MRI. A cervical coil was used. The slice width was 4 mm, and the acquisition matrix was 512×256. The sequence parameters for T1-weighted images was a repetition time (TR) of 612 ms and an echo time (TE) of 13 ms; and for T2-weighted images, a TR of 2400 ms and a TE of 114 ms was used. For patients with an ISI on T2-weighted MRI, the T2:T1 ratio at the same spinal cord level, and over an area roughly equivalent to the ISI area on T2-weighted MRI, was calculated by computer. Patients with ISI were subdivided into 2 groups according to T2/T1 ratio. Neurological status was assessed according to the Japan Orthopaedic Association (JOA) score, before and after surgery; and recovery rate, which was calculated.Results: ISI was not observed in 20 patients (group 1). The range of T2/T1 ratio of other 37 patients was from 1.28 to 2.80 and the median was 1.65. Nineteen patients were divided into group 2 (ratio range, 1.28-1.63), and 18 into group 3 (ratio range, 1.67-2.80). In group 1, there were 11 and 9 patients respectively treated by cervical open-door laminoplasty and laminectomy. In group 2, there were 13 and 6 patients respectively treated by cervical open-door laminoplasty and laminectomy. In group 3, there were 11 and 7 patients respectively treated by cervical open-door laminoplasty and laminectomy.Overall, the postoperative clinical outcome revealed a significant improvement, from a mean preoperative JOA score of 9.7±2.3 to 12.9±2.2 at final follow-up. Significant differences were observed in peoperative and postoperative JOA scores, and the recovery rate (p< 0.05) between patients with or without ISI. The average age and disease duration of patients with ISI were relatively larger. The analysis of variance showed significant differences in age, disease duration, peoperative and postoperative JOA scores, and the recovery rate (p<0.05) among three groups. In addition, the Student–Newman–Keuls test for age, disease duration and preoperative JOA score showed significant differences between groups 1 and 2 (p<0.05), groups 1 and 3 (p<0.05), and groups 2 and 3 (p<0.05). Significant differences for the final JOA score were noted between groups 1 and 3 (p<0.05), and between groups 2 and 3 (p<0.05). When comparing the recovery rates among the 3 groups, significant differences were found between groups 1 and 2 (p<0.05), groups 1 and 3 (p<0.05), and groups 2 and 3 (p< 0.05). Spearman's rank correlation showed that T2/T1 ratio was correlated with age (rs=0.391,P=0.017), symptom duration (rs=0.528,P=0.001), preoperative JOA score (rs=-0.682, P<0.05), postoperative JOA score (rs=-0.645, P<0.05) and recovery rate (rs=-0.540, P=0.001).Conclusion: Patients with ISI and higher T2/T1 ratio tend to have relatively severe preoperative state of illness and poor prognosis after surgical intervention. Spinal cord signal intensity change on T2-weighted MRI might be a predictor of a poor outcome in terms of functional recovery rate in patients underwent operations for multi-level CSM.
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