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Spine and Back Health

Explanation of MRI



I am a 48 year-old female with a history of back problems. Diagnosed with Spondolylotheis in 1993. I recently reinjured my back and had a MRI done last week. The findings are confusing as Spondolylothesis isn`t mentioned. According to the MRI report I have Grade 1 anterolisthesis of L5 on S1 with bilaterial pars defects. Moderate right and mild left nerual foraminal stenosis. What does this mean?


Hello, thank you for your question. You've been fooled by two similar terms that mean the same thing. Spondylo = "spine". Listhesis = "slippage", or "to slip". Antero = "towards the front of the body". So, "spondylolisthesis" is a generic term for when one vertebra (spinal bone) is slipped out of place relative to the others. "anterolisthesis" is just being more specific: it means you have a vertebra slipped forward relative to the one below it. The grading system describes how far it is slipped (grade 1 is the mildest, grade 4 is the worst). Bilateral = "both sides". Pars defects refer to small gaps or defects in the bone, which is what allows your vertebra to slip out of line in the first place. Finally, the "neuroforamen" is the opening on the side of the spinal canal where the nerve root exits the spine (heading down toward your sciatic nerve, the big nerve in the back of your leg). "Stenosis" means narrowing. So, "neuroforaminal stenosis" means narrowing of the opening where the nerve root comes out. I hope this helps clarify things for you. Good luck.

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Response by:

David J Hart, MD David J Hart, MD
Associate Professor of Neurosurgery
School of Medicine
Case Western Reserve University