Correlation Between Operative Outcomes of Cervical Compression Myelopathy and MRI of the Spinal Cord

Abstract

STUDY DESIGN: Magnetic resonance images of cervical compression myelopathy were retrospectively analyzed in comparison with surgical outcomes. OBJECTIVES: To investigate which magnetic resonance findings in patients with cervical compression myelopathy reflect the clinical symptoms and prognosis, and to determine the radiographic and clinical factors that correlate with the prognosis. SUMMARY OF BACKGROUND DATA: Signal intensity changes of the spinal cord on magnetic resonance imaging in chronic cervical myelopathy are thought to be indicative of the prognosis. However, the prognostic significance of signal intensity change remains controversial. METHODS: The participants in this study were 73 patients who underwent cervical expansive laminoplasty for cervical compression myelopathy. Their mean age was 64 years, and the mean postoperative follow-up period was 3.4 years. The pathologic conditions were cervical spondylotic myelopathy in 42 patients and ossification of the posterior longitudinal ligament in 31 patients. Magnetic resonance imaging (spin-echo sequence) was performed in all the patients. The transverse area of the spinal cord at the site of maximal compression was computed, and spinal cord signal intensity changes were evaluated before and after surgery. Three patterns of spinal cord signal intensity changes on T1-weighted sequences/T2-weighted sequences were detected as follows: normal/normal, normal/high-signal intensity changes, and low-signal/high-signal intensity changes. Surgical outcomes were compared among these three groups. The most useful combination of parameters for predicting prognosis was determined using a stepwise regression analysis. RESULTS: The findings showed 2 patients with normal/normal, 67 patients with normal/high-signal, and 4 patients with low-signal/high-signal change patterns before surgery. Regarding postoperative recovery, the preoperative low-signal/high-signal group was significantly inferior to the preoperative normal/high-signal group. There was no significant difference between the transverse area of the spinal cord at the site of maximal compression in the normal/high-signal group and the low-signal/high-signal group. A stepwise regression analysis showed that the best combination of surgical outcome predictors included age (correlation coefficient R = -0.348), preoperative signal pattern, and duration of symptoms (correlation coefficient R = -0.231). CONCLUSIONS: The low-signal intensity changes on T1-weighted sequences indicated a poor prognosis. The authors speculate that high-signal intensity changes on T2 weighted images include a broad spectrum of compressive myelomalacic pathologies and reflect a broad spectrum of spinal cord recuperative potentials. Predictors of surgical outcomes are preoperative signal intensity change pattern of the spinal cord on radiologic evaluations, age at the time of surgery, and chronicity of the disease.