What is myelomalacia of the cervical cord?

Myelomalacia of the Cervical Cord

Myelomalacia is the softening of the spinal cord tissue due to chronic compression or injury, representing irreversible damage to neural tissue that is best visualized on MRI as signal changes. 1 This condition is a serious complication of cervical spinal cord compression that indicates permanent tissue damage and carries significant implications for patient outcomes and treatment decisions.

Pathophysiology and Causes

Myelomalacia develops through several mechanisms:

• Chronic compression: Most commonly results from degenerative cervical spondylosis, disc herniation, or spinal stenosis
• Vascular compromise: Reduced blood flow to the spinal cord leading to ischemia
• Trauma: Severe injury causing direct damage to the cord or vascular supply
• Post-inflammatory changes: Following conditions like transverse myelitis

The pathologic process involves:

• Initial edema and inflammation
• Progressive neuronal degeneration
• Replacement of normal cord tissue with fluid-filled cystic spaces
• Eventual atrophy and gliosis of the spinal cord

Imaging Characteristics

MRI is the gold standard for diagnosing myelomalacia, showing characteristic findings:

• T2-weighted images: Hyperintense signal within the cord substance 2
• T1-weighted images: Hypointense signal or normal appearance
• Advanced cases: Cord thinning/atrophy and cystic changes within the cord
• Contrast enhancement: Typically absent in pure myelomalacia (may help distinguish from tumors)

The imaging changes in myelomalacia and gliosis are best discerned by MRI, which has superior soft-tissue resolution and multiplanar capability 2.

Clinical Presentation

Symptoms depend on the level and extent of cord involvement:

• Motor symptoms: Progressive weakness, spasticity, hyperreflexia
• Sensory symptoms: Numbness, paresthesias, loss of proprioception
• Autonomic dysfunction: Bowel/bladder disturbances
• Gait abnormalities: Wide-based, unsteady gait
• Hand dysfunction: Decreased dexterity, grip strength

Notably, some patients with myelomalacia may present with atypical symptoms. For example, severe cervical myelomalacia can sometimes present with only lower extremity symptoms and no upper extremity involvement 3.

Prevalence and Epidemiology

The prevalence of cervical myelomalacia in patients requiring cervical MRI is approximately 4.2% overall (5.6% in males and 3.0% in females), with rates increasing linearly with age until the eighth decade when it reaches 7.6% overall 4. The prevalence varies considerably based on the specialty of the referring provider, with specialists in spinal cord injury seeing the highest rates (28.7%), followed by neurological (8.4%) and orthopedic (6.4%) spine surgeons 4.

Prognostic Significance

Myelomalacia represents a poor prognostic sign for several reasons:

• Indicates irreversible damage to the spinal cord tissue 1
• Serves as an important prognostic factor for neurosurgical outcomes in patients with spondylotic myelopathy 2
• May predict poorer recovery after decompressive surgery
• Suggests advanced disease stage with potential for permanent neurological deficits

Management Considerations

Treatment decisions should be based on:

1. Severity of myelopathy:

   • Mild CSM (mJOA scale scores > 12): May be treated with either surgical decompression or nonoperative therapy in the short term (3 years) 2
   • More severe CSM (mJOA scale score ≤ 12): Should be considered for surgical decompression 2

2. Presence of myelomalacia:

   • When myelomalacia is present, surgical intervention is typically required 1
   • The goal is to prevent further progression of cord damage

3. Surgical approach:

   • Anterior approach: For focal anterior compression
   • Posterior approach: For multilevel compression or ossification of posterior longitudinal ligament
   • Combined approach: For complex cases with both anterior and posterior compression

4. Timing of intervention:

   • Early intervention is crucial when myelomalacia is present to prevent irreversible neurological deficits
   • Delayed treatment may result in permanent disability

Key Considerations for Clinicians

• MRI is essential for diagnosis and should be obtained promptly when cervical myelopathy is suspected
• The presence of myelomalacia should prompt urgent referral to a spine surgeon
• Even in the absence of upper extremity symptoms, cervical myelomalacia should be considered in patients with progressive lower extremity weakness and neurogenic bladder/bowel dysfunction 3
• Long periods of severe stenosis over many years are associated with demyelination of white matter and may result in necrosis of both gray and white matter leading to potentially irreversible deficit 2

Myelomalacia represents a serious finding that warrants prompt attention and appropriate management to prevent further neurological deterioration and optimize patient outcomes.