51 - Range of Horizontal Gaze Following Multilevel Posterior Cervical Fusion Across the Cervicothoracic Junction

Introduction: Debate exists as to whether multilevel posterior cervical fusion (PCF) should cross the cervical thoracic junction (CTJ). Multiple studies have demonstrated typical spinal radiographic parameters are not significantly changed when patients are fused above vs. across the CTJ. Yet, there is a paucity of evidence examining how horizontal gaze is affected following cervical fusion.

Aim/

Objectives: We sought to examine radiographic evidence of change in range of horizontal gaze in patients who underwent multilevel posterior cervical fusion near the cervicothoracic junction (CTJ). We compared patients whose constructs terminated caudally at C7 (Group 1) vs. those patients whose constructs continued past the CTJ to T1-T3 (Group 2). We found that overall range of horizontal gaze decreased by an average of 15.6° (p < 0.0001) with no significant difference between Group 1 and Group 2.

Methods: Retrospective analysis was performed on patients 18-100 years old who underwent primary PCF involving ≥3 segments with caudal endpoints of C7-T3. McGregor slope (McGS) and C0-C2 cobb angle were measured on lateral cervical x-rays in flexion, extension, and neutral pre- and post-cervical fusion. Statistical analysis was performed to assess for significant change in these measures both pre- and post-fusion as well as between Group 1 and Group 2.

Results: A total of 44 patients were deemed eligible. In all patients, full range of horizontal gaze as measured by McGS in flexion – extension decreased by an average of 15.6° (p < 0.0001) while C0-C2 cobb angle extension – flexion increased by an average of 3.9° (p = 0.014) pre- vs. post-fusion. Fusion across the CTJ made no difference in range of horizontal gaze in either McGS or C0-C2 cobb angle when patients were separated into Group 1 vs. Group 2.

Conclusion: Our findings demonstrate that multilevel PCF significantly decreases full range of horizontal gaze. This loss is in-part compensated for by an increase in motion above the construct at C0-C2. We did not detect a significant difference in full range of horizontal gaze when constructs terminated at or above C7 vs. across the CTJ to T1-T3. Based on our findings, spine surgeons can expect multilevel PCF to significantly decrease their patients’ range of horizontal gaze regardless of fusion across the CTJ.