Spinal Cord Shift on Magnetic Resonance Imaging at 24 Hours After Cervical Laminoplasty

Study Design. A prospective study in 19 patients after cervical laminoplasty, using magnetic resonance imaging. Objective. To evaluate the value of spinal cord shift at 24 hours after cervical laminoplasty. Summary of Background Data. Postoperative C5 palsy is a noticeable complication within 1 week after cervical laminoplasty. The root tethering due to the posterior shift of the spinal cord after laminoplasty was reported as one of the causes of C5 palsy. However, the spinal cord shift after surgery within 1 week is unknown. Methods. The posterior shift of the spinal cord was measured in 19 consecutive patients on magnetic resonance images at 24 hours and 2 weeks after cervical laminoplasty. Results. The mean posterior shift of the spinal cord at 24 hours was 2.8 mm, with the maximum at the C5 level, decreasing to 1.9 mm at 2 weeks. The posterior shift of the spinal cord at C5 was correlated with the amount of the dura mater at C4, C5, and C6 levels. In a patient with right C5 palsy, posterior shift at C5 level was 5.5 mm, decreasing to 3.0 mm at 2 weeks after surgery. The posterior shift of the spinal cord was not correlated with the sagittal alignment. Conclusion. The posterior shift of the spinal cord at 24 hours had a tendency to shift more posteriorly than that observed at 2 weeks after cervical laminoplasty. C5 palsy may be prevented if the expansion of dura mater, which is strongly correlated with the posterior shift, can be controlled.