What is Established Myelopathy?
Established myelopathy refers to chronic, long-standing spinal cord dysfunction where neurological deficits have been present and progressive over an extended period, typically months to years, as opposed to acute (≤21 days) or subacute presentations. 1, 2
Core Definition
Myelopathy is a clinical diagnosis characterized by neurological findings localized specifically to the spinal cord rather than the brain or peripheral nervous system. 3, 1 The term "established" implies:
- Chronic time course: Slow, progressive development of symptoms over months to years 1
- Stable or slowly progressive deficits: Maximum deficit reached gradually, not acutely 2
- Structural changes present: Often accompanied by irreversible spinal cord damage such as myelomalacia (softening of the spinal cord) 1
Clinical Presentation of Established Myelopathy
The constellation of symptoms includes: 4
- Motor abnormalities: Progressive weakness, clumsiness, spasticity, and hyperreflexia 1, 4
- Sensory deficits: Paresthesias, numbness, loss of proprioception, and dysesthesias 4
- Autonomic dysfunction: Bladder and bowel dysfunction 1, 4
- Pain: Often localized over the site of the lesion 4
For thoracic myelopathy specifically, the American College of Radiology reports: thoracic midback pain (76%), motor/sensory deficit (61%), spasticity/hyperreflexia (58%), and bladder dysfunction (24%). 1
Most Common Etiology
Degenerative cervical spondylotic myelopathy is the most frequent cause of established myelopathy, resulting from chronic extrinsic compression by disc-osteophyte complexes, spinal degenerative changes, and disc herniations. 1, 5 This is particularly prevalent in the cervical spine and develops insidiously over time. 3
Pathophysiological Changes in Established Disease
In chronic compression, the spinal cord undergoes progressive pathological changes: 1
- Breakdown of the blood-cord barrier
- Progressive necrosis and edema
- Development of myelomalacia (cord softening)
- Post-traumatic infarction and cavitation in severe cases
Critical caveat: The degree of radiographic abnormality may not correlate with symptom severity, and myelomalacia on imaging should not be confused with other causes of T2 hyperintensity such as demyelination, inflammation, or neoplasm. 1
Diagnostic Approach
MRI is the preferred imaging modality for evaluating established myelopathy, with superior soft-tissue resolution and multiplanar capability to assess both the spinal cord parenchyma and surrounding structures. 3, 1
For chronic compressive myelopathy: 1
- MRI without IV contrast is typically sufficient for degenerative disease
- MRI with and without IV contrast is indicated when infection, inflammation, or malignancy is suspected
Intramedullary cord signal changes on MRI in patients with spondylotic myelopathy serve as prognostic factors for neurosurgical outcomes. 3
Distinguishing from Other Conditions
Established myelopathy must be distinguished from:
- Acute myelopathy: Symptoms progress to nadir within 21 days 2
- Motor neuron diseases (ALS/SMA): Primary axonal degeneration without initial demyelination, presenting with hypertonicity, hyperreflexia, fasciculations, and absence of sensory symptoms 6
- True demyelinating diseases (MS, NMO): Primary myelin degradation with lesions disseminated in space and time 6, 1
The clinical presentation must match the anatomic localization—symptoms involving trunk, arms, and legs while generally sparing the head, distinguishing it from cerebral disease. 4