When it comes to the cervical spine, cord integrity matters most. Even mild changes can spell trouble if the cord is compromised.
Big Picture: Cervical canal stenosis isn’t just about the degree of narrowing; it’s about whether the spinal cord, itself, is at risk, too. Even without measurable stenosis, cord flattening can cause myelopathy. Understanding Dr. Lea Alhilali’s fishbowl analogy from the ARRS Neuroradiology Longitudinal Course helps clarify how to distinguish mild, moderate, and severe cases.
Key Takeaways:
- Cord first: Regardless of canal narrowing, deformity or signal changes in the cord point to a higher risk of myelopathy.
- Not just static: Static imaging may underestimate the impact; dynamic forces, repetitive microtrauma, or microischemia may drive symptoms.
- “Fishy” Analogies…
- Mild stenosis: Either ventral or dorsal CSF is effaced, but the cord still has room to “swim.”
- Moderate stenosis: Both ventral and dorsal CSF are lost, restricting cord movement.
- Severe stenosis: No CSF remains—cord is compressed, “fish” crushed.
Challenges Ahead
- Why cord flattening causes myelopathy without stenosis remains unclear, and mechanisms are still debated.
- Dynamic assessment may offer better insight than static MRI but isn’t standardized.
- Management depends on correlating imaging with clinical findings, which are often nuanced.
Bottom Line: Think of the cervical cord like a fish in a bowl: it needs space to move. Once the CSF “water” is gone, the cord, as well as the patient, suffers. Classifying stenosis by available space—not merely narrowing—sharpens diagnostic accuracy and clinical relevance.