Inverted Napoleon hat sign

Case contributed by Renan Ibrahem Adam

Presentation

Low back pain

Patient Data

Age: 45 years
Gender: Male
x-ray

There is a high grade anterior spondylolisthesis of L5 vertebra over S1 with overlapping over the sacrum.

Case Discussion

The inverted Napoleon hat sign indicates the presence of bilateral spondylolysis and significant spondylolisthesis. The dome of the hat is formed by the overlying body of L5 vertebra and the brim is formed by downward rotation of the transverse processes.

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