the winking owl sign
The (absent) pedicle sign, also called the winking owl sign, occurs on plain radiograph of the spine when a pedicle is absent .
The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other round open eye, and the spinous process to the beak of the owl on AP views of the thoracic or lumbar spine .
There is a wide etiology :
- destroyed pedicle
- spinal metastases
- intraspinal malignancies
- tuberculosis and other infections
- uncommon: primary bone lesion; lymphoma
- congenital absence/hypoplasia of a pedicle
- radiation therapy