Prognostic effect of increased postoperative MRI T2WI high signal intensity in degenerative cervical myelopathy.

Abstract

High cord signals (HCS) are common in patients undergoing surgery for degenerative cervical myelopathy (DCM). Few studies have investigated the prognostic effects of postoperative HCS changes. To investigate whether different changes in the postoperative magnetic resonance imaging (MRI) T2-weighted images (T2WIs) signal intensity ratio (SIR) is related to patient outcomes, predictors of unsatisfactory recovery, and the factors associated with changes in postoperative SIR. A retrospective chart review at a single institution. The study population included all consecutive patients who showed HCS in preoperative MRI T2WIs and underwent double-door laminoplasty for DCM from December 2017 to December 2020. Patient self-reported measures included the Japanese Orthopedic Association (JOA) score, 36-Item Short Form Survey (SF-36) physical component score, and SF-36 mental component score. Imaging measures included SIR, length of HCS, and canal narrowing ratio (CNR). We reviewed patient records and analyzed the statistical associations of MRI T2WI measures with the JOA score, SF-36 physical, and mental component scores. Fifty-three patients were categorized into three groups based on the postoperative HCS changes, identified from MRI T2WI before and after surgery: reduced (Group A, N=26); unchanged (Group B, N=12); and increased (Group C, N=15). The neurological recovery rates 12 months after surgery were 67.72%±17.45% in Group A, 51.53%±16.00% in Group B, and 13.35%±21.35% in Group C (p<.001). Significant differences across the three groups were found in symptom duration, postoperative SIR and length of HCS, pre- and postoperative CNR, recovery rate, JOA, SF-36 scores, with patients in Group C having the worst outcomes. Longer DCM symptom duration, greater preoperative CNR, and increased postoperative HCS were prognostic factors for a recovery rate<50%. Preoperative CNR, with an optimal threshold of 57.303%, was an independent risk factor for increased postoperative HCS. Less than one-third of DCM patients with preoperative HCS exhibited an increase in HCS after double-door laminoplasty and reported worse outcomes at the 12-month follow-up when compared to patients with decreased or unchanged postoperative HCS.