Schmörl nodes (often spelled Schmorl nodes) refer to protrusions of the cartilage of the intervertebral disc through the vertebral body endplate and into the adjacent vertebra. The protrusions may contact the marrow of the vertebra, leading to inflammation.
They may or may not be symptomatic, and their etiological significance for back pain is controversial. Schmörl nodes are found in 40-75% of autopsies.
Schmörl nodes are among the diagnostic criteria of Scheuermann disease 6.
A limbus vertebra is closely related to a Schmörl node as well.
It is believed that Schmörl nodes develop following back trauma, although this is incompletely understood. A more recent study suggests nucleus pulposus pressure on the weakest part of the end plate or vertebral development process during early life as possible explanation 7.
In the acute stage, Schmörl nodes can be difficult to diagnose or detect due to sclerosis around the margin of the herniation not having had time to develop.
Usually, they are small nodular lucent lesions involving the inferior endplate of lower thoracic and lumbar vertebral bodies. However, the involvement of both the inferior and the superior endplates is not uncommon. A sclerotic margin may be present.
They are better identified on CT images, showing the same pattern observed on radiographs.
Schmörl nodes are best seen on the sagittal sequences and usually exhibit the same signal characteristics as the adjacent disc.
History and etymology
It is named after Christian Georg Schmörl (1861-1932), a German pathologist who first described them in 1927.