Postoperative changes in spinal cord signal intensity in patients with spinal cord injury without major bone injury: comparison between preoperative and postoperative magnetic resonance images

OBJECTIVE Although increased signal intensity (ISI) on MRI is observed in patients with cervical spinal cord injury (SCI) without major bone injury, alterations in ISI have not been evaluated. The association between postoperative ISI and surgical outcomes remains unclear. This study elucidated whether or not the postoperative classification and alterations in MRI-based ISI of the spinal cord reflected the postoperative symptom severity and surgical outcomes in patients with SCI without major bone injury. METHODS One hundred consecutive patients with SCI without major bone injury (79 male and 21 female) with a mean age of 55 years (range 20-87 years) were included. All patients were treated with laminoplasty and underwent MRI pre and postoperatively (mean 12.5 +/- 0.8 months). ISI was classified into three groups on the basis of sagittal T2-weighted MRI: grade 0, none; grade 1, light (obscure); and grade 2, intense (bright). The neurological statuses were evaluated according to the Japanese Orthopaedic Association (JOA) scoring system and the American Spinal Injury Association Impairment Scale (AIS). RESULTS Preoperatively, 8 patients had grade 0 ISI, 49 had grade 1, and 43 had grade 2; and postoperatively, 20 patients had grade 0, 24 had grade 1, and 56 had grade 2. The postoperative JOA scores and recovery rate (RR) decreased significantly with increasing postoperative ISI grade. The postoperative ISI grade tended to increase with the postoperative AIS grade. Postoperative grade 2 ISI was observed in severely paralyzed patients. The postoperative ISI grade improved in 23 patients (23%), worsened in 25 (25%), and remained unchanged in 52 (52%). Patients with an improved ISI grade had a better RR than those with a worsened ISI grade. CONCLUSIONS Postoperative ISI reflected postoperative symptom severity and surgical outcomes. Alterations in ISI were seen postoperatively in 48 patients (48%) and were associated with surgical outcomes.