The Use of Preoperative and Intraoperative Pavlov Ratio to Predict the Risk of Postoperative C5 Palsy after Expansive Open-Door Laminoplasty for Cervical Myelopathy

BACKGROUND: No standard preoperative preventive measure has been established to decrease the occurrence of C5 palsy after expansive open-door laminoplasty. The aim of this study is to establish a reliable measured parameter in predicting the risk of the postoperative C5 palsy. MATERIALS AND METHODS: A total of 276 patients receiving posterior open-door laminoplasty for cervical spinal stenotic myelopathy were studied. The patients were divided into two groups according to the preoperative Pavlov ratio (Group A: Pavlov ratio <0.65 and Group B: Pavlov ratio ≥0.65). Correlations between the occurrence of postoperative C5 palsy and Pavlov ratio were analyzed, and Group A was further tested. The surgical procedures, clinical symptoms, and Pavlov ratio were described. RESULTS: The patients with Pavlov ratio <0.65 had a higher risk of developing postoperative C5 palsy (P < 0.05, odds ratio [OR] = 2.91). No significant difference was found in gender, age, etiology, type of operation, and pre- and postoperative Japanese Orthopaedic Association scores between patients with and without postoperative C5 palsy. The cutoff (1.01) of receiver operating characteristic curve of the postoperative Pavlov ratio of the Group A was calculated. The postoperative Pavlov ratio ≥1.01 of the patients in Group A was a significant risk factor of the development of postoperative C5 palsy (P < 0.01, OR = 10.83). CONCLUSIONS: The preoperative Pavlov ratio <0.65 at the C5 level was more likely to develop the postoperative C5 palsy. When the preoperative Pavlov ratio is <0.65, the postoperative Pavlov ratio ≥1.01 at the C5 level is a reliable predictor for the development of postoperative C5 palsy. Pavlov ratio may be one of the reasons for postoperative C5 palsy.