Cadaveric Analysis of Posterior Pharyngoesophageal Wall Thickness: Implications for Anterior Cervical Spine Surgery.

STUDY DESIGN A cadaveric study. OBJECTIVE To investigate possible variations of posterior pharyngoesophageal (PE) wall thickness in the horizontal plane and their implications for anterior spine surgery. SUMMARY OF BACKGROUND DATA Lower cervical levels (C5-7) are most commonly involved in cases of PE injury, and PE wall thickness could be one of the proposed reasons for the high incidence of PE injuries at these levels. The purpose of this study was to document thickness variations of the posterior PE wall at different cervical spine levels, because the study could provide valuable anatomical information that could reduce iatrogenic injuries caused by retractors or instrumentation. METHODS Thirteen formaldehyde-fixed cadaveric specimens were included in current study. PE specimens were harvested from epiglottis to suprasternal notch within 2 months of formaldehyde fixation and sectioned axially. Four slices corresponding to the superior and inferior borders of thyroid cartilage, cricoid cartilage, and 2  cm below cricoid cartilage were sectioned. Posterior PE wall thickness was measured at three zones as follows: median, lateral, and paramedian. Posterior PE wall thicknesses were measured by a pathologist. RESULTS Based on one-way ANOVA, posterior PE wall thickness showed several significantly different variations depending on cervical level and horizontal plane. PE walls were thinnest at the level of cricoid cartilage (P < 0.05). This difference was more pronounced in the median zone, because of thickness variations in the muscular layer (P < 0.001). CONCLUSION The posterior PE wall was thinnest in the median zone at the cricoid cartilage level. Variations in muscle layer thickness caused PE wall thickness differences. The smaller wall thickness at the level of the cricoids cartilage and in the midline zone may place it at higher risk of injury, and special care should be taken during dissection, retraction, and instrument placement. LEVEL OF EVIDENCE 3.