What causes vacuum disc sign in the spine on imaging?
Let me know in the comments.
Click to reveal the answer
Answer:
The vacuum disc sign is caused by the accumulation of gas, mainly nitrogen, within the intervertebral disc space. It is most commonly seen in degenerative disc disease where structural disc damage leads to clefts or fissures within the disc. This finding is associated with spinal segmental instability and may correlate with chronic low back pain or symptoms of nerve root compression. It can also be seen in vertebral collapse due to benign or malignant causes.
Why is it called so?
The name “vacuum disc sign” refers to the radiologic appearance of a gas collection within the intervertebral disc space that appears as a radiolucent area on plain radiographs or CT scans. The term “vacuum” describes the relative negative pressure inside degenerated discs that allows dissolved gases from surrounding tissues to accumulate and become visible. It is the spine-specific manifestation of the general vacuum phenomenon that can also occur in synovial joints elsewhere (hip, shoulder, knee) – see the related “Vacuum Joint sign” post on this site for the extraspinal form of the same underlying process.
Pathophysiology
Degeneration of the intervertebral disc leads to fissures and clefts forming in the nucleus pulposus and annulus fibrosus. With spinal movement, the pressure within the disc space fluctuates, increasing when vertebrae approximate and decreasing when they distract. This drop in pressure creates a suction effect, drawing out dissolved gas (mostly nitrogen) from adjacent tissues into the disc fissures, resulting in a visible gas collection known as the vacuum phenomenon.
Alternative names: Vacuum phenomenon in the spine; intradiscal vacuum phenomenon; phantom nucleus pulposus.
Other associated named signs: Vacuum cleft sign (a related but distinct finding – intravertebral, rather than intradiscal, gas seen in ischemic vertebral body collapse/Kummell disease); vacuum facet phenomenon (gas within a degenerated facet joint).
References
Access all radiology signs posted so far: https://radiogyan.com/radiology-signs/
Improve Content And Help Your Colleagues!
Found an error in the post? Please let us know using our contact page and we will update it with due credits!
If you wish to contribute radiological images for this case (or any other article on the website), you can submit them here and you will be duly credited: Submit radiology case