Association of magnetic resonance imaging signal changes and outcome prediction after surgery for cervical spondylotic myelopathy

Object. Few studies have evaluated the prognostic significance of different types of T2-weighted MR imaging changes in patients with cervical spondylotic myelopathy (CSM). The object of this study was to determine whether the type of increased signal intensity (ISI) was an independent predictor of outcome following central corpectomy in patients with CSM or ossification of the posterior longitudinal ligament (OPLL). Methods. Magnetic resonance images obtained in 197 patients who had undergone central corpectomy for CSM or OPLL were assessed for ISI within the cord on sagittal T2-weighted images and hypointensity on T1-weighted images. The T2-weighted changes were categorized as no change (Type 0), fuzzy (Type I), or sharp (Type 2) based on the ISI characteristics. Outcomes were assessed as a change in Nurick grade of I grade or more from preoperatively to postoperatively, and cure as a follow-up Nurick grade of 0 or I. Multilevel regression analysis was performed to identify predictors of change in Nurick grade >= 1 and cure. Results. There were 30 patients (15.2%) with Type 0, 104 patients (52.8%) with Type 1, and 63 patients (32%) with Type 2 ISI on MR images. Age, duration of symptoms, and preoperative Nurick grade were similar among the groups. A preoperative Nurick grade of 4 or 5 (OR 0.23, p < 0.001) and presence of Type 2 ISI on T2-weighted images (OR 0.48, p = 0.04) negatively influenced the probability of cure after surgery. Hypointensity on T1-weighted images was only seen in patients who had Type 2 ISI changes. Among the 63 patients with Type 2 ISI, the presence of T1-weighted hypointensity (16 patients) was found to negatively impact cure (OR 0.1, p = 0.04). Conclusions. Increased signal intensity on preoperative T2-weighted MR images was seen in more than 80% of the cases. However, only Type 2 ISI on T2-weighted images had a prognostic significance of being associated with a decreased likelihood of cure in patients with CSM or OPLL. Hypointensity on T1-weighted images predicted a lower probability of cure among patients with Type 2 ISI on T2-weighted images. (DOI: 10.3171/2011.8.SPINE11452)