Prognostic significance of the Zone of Partial Preservation (ZPP) within 72 hours of motor complete cervical spinal cord injury: a novel MRI-based approach

Study Design: A retrospective case series. Objectives: To investigate the prognostic value of the Zone of Partial Preservation (ZPP) within 72 h after cervical spinal cord injury (CSCI) with American Spinal Injury Association Impairment Scale (AIS) A and B. Setting : Department of Orthopaedic Surgery, Spinal Injuries Center, Japan Methods: The study participants were sixty-five patients with an initial diagnosis of motor complete CSCI (AIS A, n=44, AIS B, n=21) within 72 h after injury. The impact of the length of motor or sensory ZPPs on the rates of motor score recovery and conversion to AIS C/D at three months after injury were investigated. MRI-based ZPPs were defined as the residual function caudal to the presumptive primary injured segment of the spinal cord inferred from MRI, whose relevance to the motor recovery was also investigated. Results: The significant better motor recovery was demonstrated in individuals with longer lengths of sensory and MRI-based sensory ZPPs (p<0.05). Sensory ZPP length of 11 or more, MRI-based sensory ZPP length of 10 or more, and MRI-based motor ZPP length of 1 were associated to be the significant higher rates of conversion to AIS C/D with the odds ratio of 10.2 (95% CI, 1.4-76.9), 21.0 (1.8-243.0), and 8.2 (2.2-31.4), respectively (p<0.05). Conclusions: Sensory ZPPs within 72 hours after injury could be a prognostic factor of the motor recovery and conversion to AIS C/D in individuals with motor complete CSCI. ZPPs may be more useful for predicting the recovery potential combined with the MRI findings. Sponsorship : N/A