Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P116. Changes in radiographic alignment do not influence the development of postoperative C5 palsy

Abstract

BACKGROUND CONTEXT Post-operative C5 palsy is a known complication following cervical decompression, occurring more frequently after posteriorly based procedures, but also occurring after approximately 2%–6% of anteriorly based surgeries. Although several risk factors for the development of a postoperative C5 palsy have been reported, including among others, excessive cord drift, change in overall cervical alignment, and increases in C4-5 intervertebral height, no consensus has emerged on definitive causation and the cause is likely multifactorial. PURPOSE To assess the rate of C5 palsy following anterior cervical decompression and fusion (ACDF) and determine whether any radiographic parameters can predict its occurance. STUDY DESIGN/SETTING Retrospective single institution, multisurgeon patient cohort. PATIENT SAMPLE A total of 226 patients who underwent ACDF between September 2015 and September 2016 were reviewed. The average age of the sample was 59years and 51% were female. A total of 122 patients were included in the final analysis. Patients were excluded if they underwent concomitant posterior surgery or corpectomy, if no postoperative motor strength was documented, or if radiographs were inadequate for accurate measurement. OUTCOME MEASURES The primary outcome measure was the development of a C5 palsy, defined as a decrease of at least one motor grade in deltoid and/or biceps brachii muscle function in the immediate postoperative period. Preoperative and immediate postoperative radiographs were reviewed to determine whether any parameters influenced the development of a C5 palsy. These parameters included: local (C4-5) cobb angle, C2-7 cobb angle, C2-7 sagittal vertical axis (SVA), C4-5 intervertebral height (measured from the superior endplate of C4 to the inferior endplate of C5), and C2-7 cervical height (measured from the superior endplate of C2 to the inferior endplate of C7). METHODS Patient demographic, surgical, and radiographic data was reviewed, including postoperative motor examination results and pre- and postoperative radiographs. Given the small sample size for the palsy group, Mann-Whitney U test was used to compare continuous variables between independent groups and Fisher's exact test was used to compare categorical variables between groups. RESULTS Seven patients developed a postoperative C5 palsy with an overall rate of 5.7%. There were no statistically significant differences in patient age, sex, or numbers of levels fused between the palsy and nonpalsy groups. Among all radiographic parameters evaluated, there were no statistically significant differences between the groups (p>.05). However, there was a trend toward increasing kyphosis within the palsy cohort compared to the nonpalsy cohort among the changes in C2-7 cobb angle (4.09°±10.2° of kyphosis vs. 1.25°±9.18° lordosis, p=.19), C4-5 cobb angle (3.04°±6.70° kyphosis vs. 2.91°±8.46° lordosis, p=.059), and SVA (8.46 mm±8.26vs. 5.31 mm±9.04, p=.32). There was marginal significance for increased change in C4-5 cobb angle predisposing toward palsy (1.24° vs. 4.01°, p=.059). There was also a nonsignificant trend toward increasing local (0.90 mm±6.95vs. 3.37 mm±5.46, p=.35) and overall intervertebral height (1.56 mm±10.34vs. 4.26 mm±7.54, p=.54) among the palsy versus nonpalsy groups, respectively. CONCLUSIONS In this single institution series, we identified a 5.7% postoperative C5 palsy rate following ACDF. Although some have suggested that certain radiographic parameters can predict the development of C5 palsy, in our series, we could not identify any radiographic parameters which increase this risk, including changes in overall cervical or local C4-5 alignment.