Changes in Pyriform Sinus Morphology in the Head Rotated Position as Assessed by 320-Row Area Detector CT

In patients with unilateral pharyngeal paresis and dysphagia, the head is rotated to the paretic side to prevent food flow to the rotated side during swallowing. Only a few studies to date have reported on pyriform sinus morphology upon head rotation. The purpose of this study was to measure the volume, depth, and cross-sectional area of the pyriform sinus during head rotation using 320-row area detector computed tomography. We imaged the neck during head rotation at 0A degrees and at 30A degrees, 45A degrees, and 60A degrees to the left or right in nine healthy young adults and determined the volume, depth, and cross-sectional area of the pyriform sinus in each position. On the rotated side, volume and cross-sectional area were significantly decreased at 60A degrees. In contrast, volume, cross-sectional area, and depth were all significantly increased on the opposite side at 60A degrees. These results suggest that head rotation at 60A degrees significantly increases the volume, cross-sectional area, and depth of the opposite side, and significantly decreases the volume and depth of the rotated side of the pyriform sinus.