Abdom Radiol (NY). 2016 Mar;41(3):582-3. doi: 10.1007/s00261-015-0565-y.
Roller BL1, Wuertzer SD2, Dyer RB2.
Interpreting an abdominal radiograph entails more than just looking at the bowel gas pattern, or for free air. The skeletal structure can offer valuable clues to pathology. A "winking owl" (Fig. 1) metaphorically describes an absent vertebral body pedicle as seen on a standard frontal abdominal view (Fig.2) [1]. With the vertebral body as the owl's head, the absent pedicle represents the owl's "winked" eye, the normal contralateral pedicle represents the open eye, and the vertebral spinous process represents the owl's beak [2]. The sign typically indicates skeletal metastases involving the posterior vertebral body, with the lytic process in the pedicle accounting for the "wink" [1,3,4]. Lysis of over the 50% of the trabecular bone within a vertebral body body must occur before the process becomes evident radiographically however, cross-sectional imaging affords earlier detection and more complete characterization (Figs.3,4) [5].