[The radiological phenomenon of lumbar vacuum-disc (author's transl)]

Profile films of the lumbar region show the vacuum-disc phenomenon fairly frequently especially at the L5-S1 level and when there is disc degeneration. Two varieties can be distinguished : one with a well-defined enlarged medial image, and a more limited type which is often anterior, at the fibrous ring level and in contact with the vertebral plates. The latter is seen less frequently, but needs to be considered, as it precedes the changes seen in the nucleus pulposus in the intersomatic alteration. It has been shown that this image is of gaseous origin. It is caused by the liberation of gas into a newly-formed intersomatic cavity situated either in the nucleus pulposus or fibrous ring levels. The vacuum-disc phenomenon is of great diagnostic value as it is usually found in relation to degenerated discs and permits orientation of diagnosis towards classical arthrosis or Pott's pseudo-arthrosis when atypical radiological images are seen.