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Case of the Week 381

What sign is depicted on this image?

  • 46 year-old with back pain

Frontal radiograph of lumbar spine

1. Dense pedicle sign
2. Ivory vertebra
3. Sherlock Holmes sign
4. Spine sign
5. Napoleon hat sign

Additional Images - Lateral radiograph of lumbosacral junction


Additional Images


Lateral radiograph of lumbosacral junction



5. Napoleon Hat Sign



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Napoleon Hat Sign

General Considerations

  • Occurs with marked anterolisthesis of L5 on S1
  • Visible on frontal radiograph of lumbar spine
  • Implies the presence of bilateral spondylolysis and significant spondylolisthesis
    • Spondylolysis resulting in this degree of spondylolisthesis is more often congenital and/or traumatic in origin and less often degenerative
  • "Brim" of hat is formed by the downward rotation of the transverse processes
    • "Dome" of hat is body of L5
  • The sign can also be seen with marked exaggeration of the normal lordosis at the lumbosacral junction

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