Diagnostic Criteria for Malignant Spinal Cord Compression
Malignant spinal cord compression is diagnosed by the combination of clinical symptoms in a cancer patient plus radiographic evidence of compression of the dural sac and its contents (spinal cord and/or cauda equina) by an extradural tumor mass, with minimum radiologic evidence being indentation of the theca at the level of clinical features. 1
Clinical Diagnostic Criteria
The clinical diagnosis requires recognition of characteristic neurologic symptoms in patients with known or suspected malignancy:
Cardinal Clinical Features
- Back pain is present in 88-90% of patients at presentation and represents the earliest warning sign, though it is not specific for MSCC 1, 2
- Motor weakness occurs in approximately 67% of patients, with up to 50% unable to walk at presentation 1, 2
- Sensory changes including numbness, paresthesias, and a sensory level are common presenting symptoms 1, 2
- Autonomic dysfunction manifesting as bladder retention, bowel dysfunction, and sphincter disturbances occurs in 48% of patients 2
- Radicular pain extending along nerve root distributions is a characteristic symptom 2
Important Clinical Caveat
While back pain is the most common symptom, it failed to differentiate between patients with MSCC and those without MSCC in multivariate analysis, meaning back pain alone should not be used to rule in or rule out the diagnosis 1
Radiographic Diagnostic Criteria
Definitive Imaging Diagnosis
MRI of the entire spine is the gold standard diagnostic test and should be performed emergently for any patient with neurologic symptoms and a history of cancer. 2, 3
- MRI sensitivity ranges from 0.44 to 0.93 and specificity from 0.90 to 0.98 1, 2
- The minimum radiologic evidence required for diagnosis is indentation of the theca at the level of clinical features 1
- MRI is superior because it identifies multiple levels of compression and avoids the risk of neurologic progression associated with myelography 3
Alternative Imaging When MRI Unavailable
- Myelography with CT is an acceptable alternative with sensitivity 0.71 to 0.97 and specificity 0.88 to 1.00 1, 2
Specific Radiographic Features to Identify
- Indentation of the theca at the level of clinical symptoms 1, 3
- Bony retropulsion or bone fragments causing cord compression 3
- Evidence of spinal instability 3
- Extent of compression (single vs. multiple levels) 2
Subclinical MSCC
Subclinical cord compression is defined as the presence of radiographic features (indentation of the theca by extradural tumor mass) in the absence of clinical neurologic features 1. This represents an important diagnostic category as these patients require close monitoring.
Risk Stratification for Diagnosis
The American College of Clinical Oncology identifies six predictive risk factors that help determine which patients warrant urgent imaging 1:
- Inability to walk
- Increased deep tendon reflexes
- Compression fractures on plain radiographs
- Bone metastases present
- Bone metastases diagnosed more than 1 year earlier
- Age less than 60 years
Patients with zero risk factors have only 4% risk of MSCC, while those with six or more risk factors have 87% risk 1