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Spine and Back Health

Isthmic Spondylolisthesis

10/01/2009

Question:

My daughter has been diagnosed with grade 3 isthmic spondylolisthesis of the L4/L5 vertebrae. Her vertebrae are 3.3 centimeters out of alignment. The neurosurgeon recommends an operation in which, after making two long incisions (anterior and posterior), a spacer is placed between the 2 vertebrae, a bone graft is made anteriorly, and steel rods are inserted posteriorly. After the bone graft heals in about 6 months, the rods are removed.

I have 2 questions. How common is this condition and is this the best treatment option? (She is having pain and numbness in her lower back and left leg from the compression of her sciatic nerve.)

Answer:

Hello, thank you for your question. Isthmic spondylolisthesis refers to a forward slippage of one vertebra (spinal bone) over the one below it. This is not the same thing as a "slipped disc", which is a common layperson term for a herniated disc. The other main type of spondylolisthesis is "degenerative", but in the "isthmic" type there is an actual defect, or break, in the vertebra that allows it to slip.

The usual grading system is from grade 1 to grade 4. Grade 1 is 0-25% slipped forward; grade 2 is 25-50%; grade 3 is 50-75% and grade 4 is 75-100%. This condition is fairly rare to begin with, but grades 3 and 4 make up less than 10% of all cases of isthmic spondylolisthesis, so your daughter's is quite rare based on how badly slipped it is. It is also quite uncommon for such a high-grade slip to be at L4-5. The high-grade ones are usually at the level below that, where the lumbar spine meets the pelvis.

You didn't mention how old your daughter is: child, adolescent, adult? I can't tell you what the best treatment for her would be without examining her and seeing her films. This problem will NOT get better unless it is surgically stabilized, but the specific type of surgery you've described sounds pretty aggressive. I can't tell you whether it is the right choice under these circumstances. If you have doubts, you should get a second opinion, and if she is a child, make sure you are seeing a pediatric spine surgeon. 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