What is Schmorl's node?

What is Schmorl's Node?

A Schmorl's node is a herniation of the nucleus pulposus (disc material) through the cartilaginous and bony endplate into the adjacent vertebral body. 1, 2

Anatomic Definition and Pathophysiology

• Schmorl's nodes represent disc material that prolapses through the vertebral endplate into the vertebral body itself, rather than into the spinal canal like typical disc herniations 3, 2
• The herniation occurs through both the cartilaginous layer and the bony endplate of the vertebra 1, 2
• An axial load model appears to have the greatest supporting evidence for their pathogenesis, with mechanical loading and impact stress being key factors 2, 4

Epidemiology and Clinical Significance

• Schmorl's nodes are extremely common, with postmortem studies estimating that greater than 70% of the population has them 1
• They are most commonly found in the lumbar spine, particularly at the thoracolumbar junction 5, 4
• The vast majority are asymptomatic and discovered as incidental findings on imaging 1, 2
• Activities involving repetitive spinal loading such as horseback riding and heavy lifting are associated with their development 4, 6

Clinical Presentation (When Symptomatic)

While most Schmorl's nodes are asymptomatic, they can rarely cause acute back pain and, even less commonly, radiculopathy. 1, 2

• Symptomatic nodes are thought to result from the inflammatory response triggered by herniation of nucleus pulposus into the well-vascularized vertebral body 2
• Acute presentations may show surrounding cortical edema and enhancement on MRI, suggesting an acute Schmorl's node 1
• In rare cases, large "giant" variants can extend posteriorly through the vertebral body cortex into the epidural space, potentially compressing nerve roots 1, 3
• Lumbar Schmorl's nodes are frequently associated with disc degenerative disease and back pain 5

Diagnostic Imaging Considerations

MRI is the imaging modality of choice for diagnosing Schmorl's nodes, as it has superior capability to detect edema, neovascularization, and extruded disc material. 1

Critical Diagnostic Pitfall:

• On PET/CT imaging, recent Schmorl's nodes with an osteosclerotic rim can exhibit uptake and may be confused with malignant bone metastases in patients with cancer 4
• Use MRI characteristics and low-dose CT to differentiate Schmorl's nodes from malignancy 4
• Do not assume all vertebral uptake on PET/CT represents malignancy in elderly patients, as degenerative changes including Schmorl's nodes can cause false-positive findings 4

Management Approach

The mainstay of treatment for both asymptomatic and symptomatic Schmorl's nodes is conservative therapy. 1, 2

• Medical management is the first-line approach for symptomatic cases 2
• Consider the patient's activity level and occupation when planning treatment, as certain activities involving repetitive spinal loading may exacerbate the condition 4
• Surgical intervention is reserved for rare cases:
  • Persistent radiculopathy from compression by a "tunneling" Schmorl's node extending into the epidural space may require surgical decompression and removal of disc material 1
  • Severe compromise of vertebral body integrity with pathologic fracture may necessitate vertebrectomy and fusion 7
• In rare giant variants, percutaneous biopsy has been reported to provide both definitive diagnosis and, surprisingly, symptom resolution 3