Three-Dimensional Quantitative Analysis of Spinal Cord Dynamics During Anterior Cervical Decompression and Fusion: New Insights Using Intraoperative Ultrasonography

Multicenter retrospective observational study. To quantitatively evaluate spinal cord pulsatile motion during anterior cervical decompression and fusion (ACDF) and identify factors affecting spinal cord dynamics. Intraoperative ultrasonography is useful to assess neural decompression during cervical spinal surgery. While spinal cord pulsation has been qualitatively evaluated, detailed quantitative analyses of three-dimensional spinal cord motion are lacking. One hundred nine intervertebral spaces of 50 patients (32 men and 18 women; mean age: 66.9&#xb1;11.6&#xa0;yr) who underwent ACDF were evaluated. Two-dimensional video measurement software was used to quantify anteroposterior pulsation and craniocaudal sliding motion of the spinal cord in intraoperative ultrasound recordings. In addition, correlations between cervical alignment parameters (C2-7 and O-C2 angles) and spinal cord pulsation characteristics were analyzed. Craniocaudal sliding motion was significantly greater than anteroposterior pulsation in both amplitude (1.09&#xb1;0.93 vs. 0.34&#xb1;0.21&#xa0;mm, P <0.001) and velocity (16.75&#xb1;11.12 vs. 5.39&#xb1;4.26&#xa0;mm/s, P <0.001). Directional analysis revealed greater velocities from posterior to anterior than from anterior to posterior (5.30&#xb1;5.12 vs. 4.47&#xb1;4.12&#xa0;mm/s, P =0.00489) and from cranial to caudal than from caudal to cranial (16.53&#xb1;11.10 vs. 11.59&#xb1;7.71&#xa0;mm/s, P <0.001). The maximum anteroposterior amplitude was significantly greater at the C4/5 level than at the C3/4 or C6/7 level ( P =0.0027). The C2-7 angle showed a moderate positive correlation with craniocaudal sliding parameters (amplitude: r =0.467, P <0.001; velocity: r =0.41, P <0.001) and a weak positive correlation with anteroposterior pulsatile parameters. This first quantitative three-dimensional analysis of spinal cord motion during ACDF revealed that craniocaudal sliding motion exceeded anteroposterior pulsation. The preferential direction from cranial to caudal indicated the brain pulsation to be the major origin. The C4/5 level exhibited maximum anteroposterior motion, which may be related to C5 palsy pathophysiology. Increased cervical lordosis promoted both types of motion, particularly craniocaudal sliding. These findings may guide intraoperative neural assessments during cervical decompression procedures.