What is the pathophysiology and management of myelomalacia with spinal stenosis?

Pathophysiology of Myelomalacia with Spinal Stenosis

Myelomalacia is a pathological softening of the spinal cord that occurs primarily due to chronic compression from spinal stenosis, leading to ischemic damage, progressive necrosis, and neurological deterioration.

Pathophysiological Mechanisms

Primary Mechanisms of Spinal Cord Injury

• Degenerative disease (spondylotic myelopathy) is the most common cause of extrinsic compression leading to myelomalacia, particularly prevalent in the cervical spine 1, 2
• Compression factors include:
  • Spinal degenerative changes and disc herniations 1
  • Osteophyte formation and malalignment 1
  • Congenitally short pedicles that accentuate compression 1
  • Epidural lipomatosis in some cases 1
• Post-surgical complications such as seromas, pseudomeningoceles, hematomas, and epidural abscesses can cause extrinsic compression 1
• Tumors in extradural and intradural extramedullary spaces can compress the spinal cord 1

Vascular Mechanisms

• Spinal cord ischemia is a significant contributor to myelomalacia development 2
• Vascular malformations can cause progressive myelopathy through venous hypertension and spinal cord edema 1, 3
• Breakdown of the blood-cord barrier leads to patchy intramedullary enhancement 1
• Ischemic damage can result from:
  • Compromised blood supply due to compression 2
  • Vascular "steal" phenomenon in cases of vascular malformations 3
  • Chronic inflammation affecting microcirculation 2

Pathological Progression

• Initial compression leads to mechanical deformation of the spinal cord 2, 4
• Progressive cascade of events includes:
  • Breakdown of the blood-cord barrier 2
  • Development of edema that worsens compression and further compromises blood supply 2
  • Progressive necrosis in affected areas 2
  • Post-traumatic infarction and cavitation 2
  • Development of myelomalacia and gliosis 1
• Intramedullary cord signal changes represent important prognostic factors for neurosurgical outcomes 1

Imaging Findings

• MRI is the gold standard for detecting myelomalacia and gliosis 1
• Characteristic findings include:
  • T2 hyperintensity within the spinal cord 2
  • Possible enhancement at and below the level of stenosis 1
  • Cord atrophy in chronic cases 2
• IV contrast is typically not required for diagnosis of spondylotic myelopathy, but characteristic patterns of enhancement can be seen immediately at and below a level of stenosis 1
• Diffusion-weighted imaging can show signal alteration earlier than T2-weighted images in acute ischemic injury 2

Clinical Manifestations and Management

Clinical Presentation

• Symptoms depend on the level and severity of compression 1
• Common presentations include:
  • Progressive weakness and sensory deficits 5
  • Gait disturbances and balance problems 4
  • Bowel or bladder dysfunction in severe cases 1
  • Pain and numbness radiating to extremities 6

Management Approaches

• Surgical decompression is the mainstay of treatment for symptomatic spinal stenosis with myelomalacia 1, 5
• Surgical options include:
  • Anterior decompression for direct removal of compressive elements 4
  • Posterior decompression approaches for multisegment compression 4
  • Combined approaches in complex cases 4
• Fusion is often recommended with decompression to prevent instability and kyphotic deformity 1
• Laminectomy alone is associated with higher risk of reoperation due to restenosis, adjacent-level stenosis, and postoperative kyphotic deformity 1

Common Pitfalls and Caveats

• Myelomalacia should not be confused with other causes of T2 hyperintensity such as demyelination, inflammation, or neoplasm 2
• The presence of cord signal changes does not always correlate with clinical outcomes 2
• Imaging must be interpreted in conjunction with clinical findings, as the degree of radiographic abnormality may not match symptom severity 2
• Remarkable recovery is possible even with profound neurological deficit, a delay in treatment, and in the presence of myelomalacia, provided the spinal cord is adequately decompressed 5
• Intraoperative hypotension should be strictly avoided during surgical decompression to prevent further ischemic damage 5