Schmorl Nodes

By admin Last updated Feb 28, 2024

Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.

Title: 5-Minute Orthopaedic Consult, 2nd Edition

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Schmorl Nodes

Andrew P. Manista MD

Basics

Description

Schmorl nodes are intraosseous vertebral
lesions that are common incidental findings on plain radiographs and CT
and MRI scans of the spine.
- These nodes represent disc material that
  has herniated through weak areas in the adjacent vertebral endplates
  into the vertebral body.
- In some cases, these weak areas may be
  the physiologic sequelae of the regression of vascular canals near the
  end of vertebral growth (particularly in young patients), whereas in
  other cases they represent a weakened endplate or subchondral bone.
- Such herniations also may occur through
  pathologically weakened bone, and they usually are found in the
  thoracic or lumbar spine, although there have been reports of Schmorl
  nodes of the cervical spine.
These lesions were first described by Christian Georg Schmorl (1,2) as the cause of Scheuermann kyphosis, which results from decreased growth of the anterior portion of the endplates of at least 3 adjacent vertebral bodies.
- Although the origin of Scheuermann
  kyphosis remains unclear, Schmorl nodes are unlikely to be the cause
  because they are not universally present.
Synonyms: Vertebral endplate irregularities; Intraosseous disc herniations

Epidemiology

Incidence

~10% of the general population (3)
No gender predilection
Age ranging from childhood to old age, depending on the predisposing condition

Risk Factors

Genetics

No specific genetic correlation has been made (4,5).
Metabolic bone diseases with genetic
predispositions may predispose persons to an increased incidence of
intraosseous disc herniation secondary to decreased bone density or
defective bony matrix of the vertebral bodies.

Etiology

Degenerative or acute rupture of the disc
endplate and extrusion of the nucleus pulposus occur with sufficient
force to penetrate the vertebral body superior or inferior to it.
Penetration may be secondary to acute trauma in the case of a normal vertebra and disc.
In the degenerative setting, penetration may occur slowly over time because of a weakened vertebral body.
Often, no obvious cause is found.

Associated Conditions (6)

Scheuermann (juvenile) kyphosis
Trauma
Osteoporosis and other metabolic disorders
Neoplastic disorders
Degenerative disc disease

Diagnosis

Signs and Symptoms

Patients may be asymptomatic or may have pain secondary to Schmorl nodes.
Symptoms prompting radiographs may not necessarily be caused by this lesion.
Symptoms usually relate to the
degenerative change or insufficiency of the particular disc and consist
of axial backache or back pain.
Pain may radiate laterally around the trunk, but not distally down the extremities.

Physical Exam

Tenderness may or may not be elicited by deep palpation or percussion over the spine.
The degrees of kyphosis in the spine should be estimated.
A complete neurologic exam should be performed, but a neurologic deficit is unlikely.
- If present, other causes should be sought.

Tests

Imaging

Conventional radiographs show
indentations or “pits” in the vertebral body, with radiolucencies
within the body surrounded by varying degrees of sclerosis.
- Variable degrees of disc thinning may be present as a result of the displaced nucleus.
- Benign-appearing lesions
MRI may show low signal on T1-weighted
and high signal on T2-weighted images in the setting of acute
intraosseous herniation, which is more likely to be symptomatic (7).
- Old, usually asymptomatic lesions show the opposite findings on T1- weighted and T2-weighted images.
- MRI is more sensitive than plain radiographs in detecting the lesion.
Bone scanning may be useful in differentiating an acute lesion from an older lesion, although MRI is the standard.

Differential Diagnosis

Degenerative subchondral cyst
Bone neoplasm: Osteoid osteoma, metastatic cancer to bone, aneurysmal bone cyst, early EOG, lymphoma, multiple myeloma

P.369

Treatment

General Measures

Treatment is symptomatic.
- In the presence of an acute intraosseous
  herniation, NSAIDs and rest are the mainstay of care until the patient
  is able to resume normal activity.
- Bracing may be initiated for comfort if needed.

Special Therapy

Physical Therapy

Physical therapy may help with persistent backaches.
Should consist of extensor strengthening and flexibility and endurance training

Medication

First Line

NSAIDs

Surgery

This condition is not a surgical entity.

Follow-up

Prognosis

Prognosis is generally good (8).

Complications

In the presence of loss of substantial disc space,
degenerative joint disease of the facet joints may result, with
additional symptoms.

Patient Monitoring

If the diagnosis is unclear, or if pain
does not resolve within 6–8 weeks, serial radiographs should be taken
to ensure that the lesion does not grow or change in character.
An MRI scan also may help rule out a malignant disease.

References

1. Schmorl GC. Die pathologische Anatomie der Wirbelsaule. Verh Dtsch Ges Orthop 1927;21: 3–41.

2. Vernon-Roberts B. Christian Georg Schmorl. Pioneer of spinal pathology and radiology. Spine 1994;19:2724–2727.

3. Hamanishi C, Kawabata T, Yosii T, et al. Schmorl’s nodes on magnetic resonance imaging. Their incidence and clinical relevance. Spine 1994;19: 450–453.

4. Hurxthal LM. Schmorl’s nodes in identical twins. Their probable genetic origin. Lahey Clin Found Bull 1966;15:89–92.

5. Karppinen
J, Paakko E, Raina S, et al. Magnetic resonance imaging findings in
relation to the COL9A2 tryptophan allele among patients with sciatica. Spine 2002;27:78–83.

6. Warner
WC, Jr. Kyphosis. In: Morrissy RT, Weinstein SL, eds. Lovell and
Winter’s Pediatric Orthopaedics, 6th ed. Philadelphia: Lippincott
Williams & Wilkins, 2006:797–837.

7. Seymour R, Williams LA, Rees JI, et al. Magnetic resonance imaging of acute intraosseous disc herniation. Clin Radiol 1998;53:363–368.

8. Murray PM, Weinstein SL, Spratt KF. The natural history and long-term follow-up of Scheuermann kyphosis. J Bone Joint Surg 1993;75A:236–248.

Miscellaneous

Codes

ICD9-CM

722.30 Schmorl node

Patient Teaching

FAQ

Q: With what spine condition are Schmorl nodes most commonly associated?

A: Scheuermann kyphosis.

Q: What is the recommended treatment for most patients with Schmorl nodes?

A: Observation and nonoperative management.