Defining "Not Densely Myelopathic" in This Clinical Context
In this 62-year-old woman with 8mm AP canal diameter, hyperreflexia, and isolated biceps weakness, "not densely myelopathic" would be indicated by the absence of T2 hyperintense signal changes within the spinal cord on MRI, particularly the absence of diffuse or confluent intramedullary signal abnormality suggesting myelomalacia or gliosis. 1
Key MRI Findings That Define Absence of Dense Myelopathy
The distinction between radiculopathy with early/mild myelopathy versus established dense myelopathy centers on cord signal characteristics:
No T2 hyperintense signal within the cord substance - The absence of bright signal on T2-weighted imaging within the spinal cord parenchyma suggests the cord has not yet developed myelomalacic changes despite compression 1
Preserved cord morphology without atrophy - The cord maintains normal caliber and contour rather than showing focal thinning or deformity that accompanies chronic myelopathy 1
Absence of contrast enhancement - No local enhancement on contrast-enhanced MRI, which would suggest active inflammatory or ischemic cord injury 2
Clinical-Radiological Correlation
The clinical presentation you describe creates diagnostic complexity:
Hyperreflexia suggests upper motor neuron involvement, which technically indicates some degree of myelopathy 1
However, isolated biceps weakness (C5-C6 myotome) with 8mm stenosis may represent radiculopathy rather than myelopathy, as lower motor neuron involvement in cervical stenosis typically occurs 1-4 levels below the structural stenosis level 3
The 8mm AP dimension represents severe stenosis (normal is >13mm; absolute stenosis is ≤10mm), placing this patient in a critical zone where cord compression exists but dense myelopathic changes may not yet be established 4
Distinguishing Features of "Not Dense" Myelopathy
Absent findings that would indicate dense myelopathy:
No centromedullary T2 hyperintensity extending over multiple segments - This pattern suggests venous hypertensive myelopathy or advanced cord injury 2
No flow voids on dorsal cord surface - These would indicate venous congestion from chronic compression 2
No progressive deterioration of symptoms - Stable or slowly progressive symptoms rather than rapid neurologic decline suggest the cord retains compensatory capacity 2
Absence of gait disturbance, fine motor deficits, or bowel/bladder dysfunction - These indicate established myelopathy rather than early changes 5, 6
Critical Pitfall to Avoid
The presence of hyperreflexia alone does not define dense myelopathy - This patient may have myeloradiculopathy (concurrent radiculopathy with early myelopathic signs) rather than established myelopathy 5. Studies show that 18.2% of patients coded for radiculopathy actually have concurrent myelopathic symptoms that go unrecognized 5.
The key distinction is whether MRI shows intrinsic cord signal abnormality (dense myelopathy) versus cord compression without signal change (not dense myelopathy, though compression is severe) 1.
Imaging Algorithm for Classification
MRI spine with and without contrast is the definitive study to make this determination 1:
- T2-weighted sagittal and axial sequences - Primary sequences to identify intramedullary signal changes 1
- T1-weighted post-contrast sequences - To exclude enhancement suggesting active cord injury 2
- Evaluation of entire spine - May be beneficial even with localized symptoms, as multilevel disease is common 1
The absence of T2 hyperintense cord signal despite severe stenosis (8mm) and hyperreflexia would classify this as "not densely myelopathic," though surgical decompression should be strongly considered given the severe stenosis and upper motor neuron signs to prevent progression to dense myelopathy 4, 6.