Schmorl nodes, also referred as intravertebral disc herniations, 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.
Quiescent Schmorl nodes are extremely common found in around 75% of autopsies, at all ages, more frequently in males 9.
Chronic Schmorl nodes are usually asymptomatic, and their etiological significance for back pain is controversial. Acute Schmorl nodes, in contrast, are uncommon and are associated with inflammation and symptoms 9.
It is believed that Schmorl 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, Schmorl nodes can be difficult to diagnose on plain radiography 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.
Schmorl nodes are better identified on CT images, showing the same pattern observed on radiographs.
Schmorl nodes are best seen on the sagittal sequences and usually exhibit the same signal characteristics as the adjacent disc, with a thin rim of sclerosis at the margins.
Acute herniation can appear more aggressive with surrounding bone marrow edema and peripheral enhancement 9. The gas extrusion sign may be present which refers to hypointensity in the intervertebral disc space across all pulse sequences 10. These acute features evolve gradually over months but may take over a year 9,10.
Acute Schmorl nodes have been reported to be FDG-PET avid 9.
History and etymology
It is named after Christian Georg Schmorl (1861-1932), a German pathologist who first described them in 1927 9.
For chronic Schmorl nodes, there are few differentials as they have characteristic appearances.
For acute Schmorl nodes consider:
- however compared with infection, acute Schmorl nodes will have more focal endplate changes, no fever, and no epidural or prevertebral phlegmonous changes 10
- malignancy 9
- 1. McFadden KD, Taylor JR. 1989. End-plate lesions of the lumbar spine. Spine. 14(8):867-9. PMID 2781398.
- 2. Peng B, Wu W, Hou S, Shang W, Wang X, Yang Y. 2003. The pathogenesis of Schmorl's nodes. J Bone Joint Surg Br. 85(6):879-82. PMID 12931811.
- 3. Takahashi K, Miyazaki T, Ohnari H, Takino T, Tomita K. 1995. Schmorl's nodes and low-back pain. Analysis of magnetic resonance imaging findings in symptomatic and asymptomatic individuals. Eur Spine J. 4(1):56-9. PMID 7749909.
- 4. Grivé E, Rovira A, Capellades J et-al. Radiologic findings in two cases of acute Schmörl's nodes. AJNR Am J Neuroradiol. 1999;20 (9): 1717-21. Pubmed citation
- 5. Die gesunde und kranke Wirbelsäule im Röntgenbild. By G. SCHMORL and H. JUNGHANNS, 2nd edition, xii. (Pp. 281, 299 figures; bound, D.M. 69.) Stuttgart: G.Thieme Verlag. 1951.
- 6. Resnick D, Niwayama G. Intravertebral disk herniations: cartilaginous (Schmorl's) nodes. Radiology. 1978;126 (1): 57-65. Pubmed citation
- 7. Dar G, Masharawi Y, Peleg S et-al. Schmorl's nodes distribution in the human spine and its possible etiology. Eur Spine J. 2010;19 (4): 670-5. doi:10.1007/s00586-009-1238-8 - Free text at pubmed - Pubmed citation
- 8. Abu-Ghanem S, Ohana N, Abu-Ghanem Y et-al. Acute schmorl node in dorsal spine: an unusual cause of a sudden onset of severe back pain in a young female. Asian Spine J. 2013;7 (2): 131-5. doi:10.4184/asj.2013.7.2.131 - Free text at pubmed - Pubmed citation
- 9. Diehn FE, Maus TP, Morris JM et-al. Uncommon Manifestations of Intervertebral Disk Pathologic Conditions. Radiographics. 2016;36 (3): 801-23. doi:10.1148/rg.2016150223 - Pubmed citation
- 10. Laur O, Mandell JC, Titelbaum DS, Cho C, Smith SE, Khurana B. Acute Nontraumatic Back Pain: Infections and Mimics. (2019) Radiographics : a review publication of the Radiological Society of North America, Inc. 39 (1): 287-288. doi:10.1148/rg.2019180077 - Pubmed
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