Orthopaedic Surgery - Schmorl Nodes

Basics

Schmorl nodes are:

Intraosseous herniations of intervertebral disc material

through a vertebral endplate and into the adjacent:

Vertebral body.

They are common incidental findings on:

Plain radiographs

CT

and

MRI of the spine.

Synonyms

Schmorl nodes may also be described as:

Intraosseous disc herniations

or

Vertebral endplate defects or irregularities.

Pathoanatomy

The lesion develops when:

Nucleus pulposus or other disc material penetrates through the superior or inferior vertebral endplate.

This produces an indentation or defect within the:

Adjacent vertebral body.

Endplate Vulnerability

In younger patients, some endplate weak points may be related to the normal regression of:

Vascular channels

near the end of vertebral growth.

In other patients, Schmorl nodes develop through:

Degenerated or weakened endplates

or weakened:

Subchondral vertebral bone.

Typical Location

Schmorl nodes most commonly occur in the:

Thoracic spine

and

Lumbar spine.

They have also been described in the:

Cervical spine, although this is much less common.

Historical Background

The lesions were described by:

Christian Georg Schmorl.

They were historically associated with:

Scheuermann kyphosis.

Relationship to Scheuermann Kyphosis

Scheuermann kyphosis is characterized by anterior vertebral wedging involving multiple adjacent vertebral bodies.

Although Schmorl nodes are frequently seen in this disorder, they are:

Not consistently present

and are therefore unlikely to be the sole cause of:

Scheuermann kyphosis.

Epidemiology

Schmorl nodes are:

Common.

Historical studies have reported them in approximately:

10% of the general population

although prevalence varies considerably depending on:

Age

Imaging technique

and

Definition used.

Age

They may occur from:

Childhood through old age.

The age at presentation depends partly on the underlying cause, such as:

Developmental endplate weakness

Trauma

Degeneration

or

Metabolic bone disease.

Sex

There is no strong consistent:

Sex predilection.

Genetics

No specific single-gene association has been established.

However, some inherited:

Metabolic bone disorders

may indirectly increase susceptibility by reducing:

Bone density

or altering the:

Vertebral bony matrix.

Risk Factors

Potential predisposing factors include:

Endplate weakness

Osteoporosis

Degenerative disc disease

High axial loading

Spinal trauma

Metabolic bone disease

Neoplastic weakening of bone

Etiology

Schmorl nodes form when sufficient force or structural weakness allows disc material to breach the:

Vertebral endplate.

Acute Mechanism

In otherwise normal bone, an acute lesion may occur after:

Trauma

or substantial:

Axial compressive loading.

The force causes rupture or deformation of the endplate with penetration of disc material into the vertebral body.

Degenerative Mechanism

In degenerative conditions, penetration may occur:

Gradually over time

because of progressive weakening of the:

Endplate

and

Subchondral bone.

Unknown Cause

In many patients, there is:

No identifiable triggering event.

Associated Conditions

Schmorl nodes may be associated with:

Scheuermann kyphosis

Spinal trauma

Osteoporosis

Metabolic bone disease

Degenerative disc disease

Neoplastic disease

Diagnosis

Most Schmorl nodes are discovered:

Incidentally on imaging.

Clinical correlation is important because the presence of a Schmorl node does not necessarily mean that it is the source of:

Back pain.

Signs and Symptoms

Many patients are:

Asymptomatic.

Symptomatic Nodes

When symptomatic, pain is usually related to:

Acute endplate injury

Bone marrow edema

or associated:

Disc degeneration.

Pain Pattern

Typical symptoms include:

Axial back pain

or

Localized spinal ache.

The pain may spread:

Laterally around the trunk

but usually does not follow a distal radicular pattern into the:

Arm

or

Leg.

Acute Symptomatic Lesion

An acutely formed Schmorl node may be more painful because of:

Inflammatory change

and

Bone marrow edema

around the endplate defect.

History

Important historical features include:

Recent trauma

Heavy axial loading

Chronic back pain

Known osteoporosis

History of malignancy

Metabolic bone disease

Physical Examination

Physical findings are usually:

Nonspecific.

Spinal Tenderness

Deep palpation or percussion over the involved spinal level may or may not reproduce:

Localized tenderness.

Spinal Alignment

The degree of:

Thoracic kyphosis

or other spinal deformity should be assessed.

This is particularly relevant when:

Scheuermann disease

is suspected.

Neurologic Examination

A complete neurologic examination should be performed.

Assess:

Motor strength

Sensation

Reflexes

and

Long-tract signs when appropriate.

Neurologic Deficit

An isolated Schmorl node typically does:

Not produce neurologic deficit.

If weakness, sensory loss, bowel or bladder dysfunction, or objective radiculopathy is present, another cause should be sought.

Imaging

Plain Radiographs

Radiographs may demonstrate:

Indentation or pitting of the vertebral endplate

with a focal intraosseous lucency surrounded by varying degrees of:

Sclerosis.

Chronic Appearance

Older lesions often appear:

Well corticated

or

Sclerotic

and have a benign appearance.

Disc-Space Changes

Associated:

Disc-space narrowing

may be present if there is significant loss of disc material or coexisting degenerative disease.

MRI

MRI is more sensitive than plain radiographs for identifying:

Schmorl nodes

and determining whether a lesion is:

Acute or chronically inactive.

Acute MRI Findings

Acute symptomatic lesions may demonstrate:

Low signal on T1-weighted images

and

High signal on T2-weighted or fluid-sensitive sequences

in the adjacent vertebral marrow.

These findings reflect:

Bone marrow edema and inflammatory change.

Chronic MRI Findings

Chronic nodes generally have less surrounding:

Bone marrow edema

and may develop a well-defined:

Sclerotic margin.

CT

CT demonstrates the:

Bony endplate defect

and surrounding sclerosis in excellent detail.

It is usually not necessary when MRI and radiographs adequately establish the diagnosis.

Bone Scintigraphy

Bone scintigraphy may show increased uptake in:

Acute or metabolically active lesions.

Historically it was used to distinguish:

Recent

from

Old lesions.

MRI is generally more informative for this purpose.

Differential Diagnosis

Important alternatives include:

Degenerative subchondral cyst

Vertebral neoplasm

Infection

and other intraosseous lesions.

Neoplastic Differential Diagnosis

Possible tumors that can resemble a vertebral endplate lesion include:

Osteoid osteoma

Metastatic carcinoma

Aneurysmal bone cyst

Lymphoma

Multiple myeloma

and other primary bone tumors.

Infection

Discitis or vertebral osteomyelitis should be considered when imaging demonstrates:

Endplate destruction

Disc-space inflammatory change

or when the patient has:

Fever

Elevated inflammatory markers

or systemic illness.

Treatment

General Principles

Most Schmorl nodes require:

No specific treatment.

Management is directed toward symptoms rather than the radiographic finding itself.

Asymptomatic Lesions

Incidental, asymptomatic Schmorl nodes require:

Observation only.

Acute Symptomatic Lesions

For an acute symptomatic intraosseous disc herniation, treatment usually includes:

Relative rest

Activity modification

and

Analgesic or anti-inflammatory medication.

Activity

Patients may reduce painful:

Lifting

Impact loading

and other aggravating activities temporarily.

Normal activity is resumed progressively as:

Pain improves.

Bracing

A spinal brace may occasionally be used for:

Short-term comfort

in patients with substantial acute pain.

It is not routinely necessary.

Physical Therapy

Persistent mechanical back pain may improve with physical therapy emphasizing:

Spinal extensor strengthening

Flexibility

Core conditioning

Postural training

Endurance.

Medication

NSAIDs may be used as first-line medication for:

Pain and inflammation

when not contraindicated.

Other Analgesics

Acetaminophen may also be used for:

Symptomatic pain control.

Surgery

An uncomplicated Schmorl node is:

Not considered a surgical disorder.

Surgery is not indicated for the lesion itself.

If surgery is required, it is usually because of a different associated condition such as:

Instability

Severe deformity

Neural compression

or another spinal pathology.

Follow-Up

Most patients do not require routine imaging follow-up when the appearance is:

Typical

and symptoms resolve.

Persistent Pain

If pain does not improve within approximately:

6–8 weeks

or if the diagnosis remains uncertain, repeat imaging may be appropriate.

Serial Radiographs

Serial radiographs can help determine whether the lesion:

Remains stable

or shows unexpected:

Growth

Bone destruction

or change in character.

MRI for Uncertain Diagnosis

MRI is useful when persistent symptoms raise concern for:

Malignancy

Infection

Acute fracture

or another cause of vertebral pain.

Prognosis

The prognosis is generally:

Good.

Most Schmorl nodes remain:

Asymptomatic

or cause only temporary symptoms.

Acute Lesions

Pain associated with an acute node generally improves as:

Bone marrow edema and endplate inflammation resolve.

Complications

Schmorl nodes themselves rarely cause major complications.

Degenerative Disc Disease

Substantial disc involvement may contribute to:

Loss of disc height

and progressive:

Degenerative disc disease.

Facet Joint Degeneration

Loss of disc height can increase loading across the:

Facet joints

and contribute to:

Facet arthrosis

with additional mechanical back pain.

Patient Monitoring

Patients should be reassessed if they develop:

Persistent or worsening pain

Night pain

Constitutional symptoms

Neurologic deficits

or imaging changes inconsistent with a typical benign Schmorl node.

Key Principle

Schmorl nodes are intraosseous herniations of intervertebral disc material through a vertebral endplate into the adjacent vertebral body.

They are common incidental findings and usually require:

No treatment.

When symptomatic, especially in an acute lesion with MRI evidence of:

Bone marrow edema, management is generally conservative with:

Rest, activity modification, NSAIDs or other analgesia, and rehabilitation.

Atypical imaging findings, persistent pain, or neurologic symptoms should prompt evaluation for:

Malignancy, infection, fracture, or another spinal disorder.