A Slipped Disc Can Shrink on Its Own
On follow-up MRI scans, the slipped discs with the scariest-sounding names are the ones that most often shrink back on their own.
In clinic, I see people with a slipped disc and pain shooting down one leg all the time. Many of them ask me the same thing, “Do I need surgery?”
My answer starts with the question I tell every patient to ask any surgeon, “What happens if I wait?” For the most common cause of sciatica, the answer surprises a lot of people. By the end of this, you’ll know the one question to ask about your own scan.
What actually slipped?
Between the bones of your spine sit cushions called discs, each with a tough outer ring around a soft, jelly-like center.
When a disc herniates, some of that soft center pushes out through a weak spot in the ring. If it presses on a nerve root low in your back, you get sciatica. That’s the pain that runs from your buttock down the back of your leg.
Your MRI report names the shape with one word, usually bulge, protrusion, extrusion or sequestration, from mildest-sounding to scariest. Sequestration means a piece has broken off and is lying loose.
Then why would it shrink?
While the soft center stays inside its ring, it’s mostly out of reach of your blood supply. Once it breaks through, your body’s clean-up cells can finally get to it.
As the cells move in, tiny new blood vessels grow toward the loose piece, and enzymes break it down over months. That’s why the pieces that have traveled furthest tend to shrink most often.
In one review of the scan studies, most extrusions and nearly all sequestrations got smaller, while bulges shrank far less often. That’s what the scans show, though, and whether your pain eases at the same pace is less certain.
So should you wait?
In a Dutch trial, people with severe sciatica were picked by chance for early surgery or for waiting. By a year, both groups had ended up in about the same place, though surgery got people there faster. About four in ten of those who waited had surgery anyway.
It drives me crazy when someone tells a patient they’ll be paralyzed without surgery. I don’t think it’s right to put the fear of God in patients. Some people need surgery sooner, and some need it later.
If your surgeon has already advised an operation, talk it through with them before you change any plans. Some signs mean you shouldn’t wait at all. Go to the ER today if you have trouble controlling your bladder or bowels, numbness around your groin or bottom, or leg weakness that is getting worse.
- The soft center breaks through It pushes out of the disc’s tough ring and can press on a nerve.
- It meets your blood supply Outside the ring, your clean-up cells can reach it.
- Enzymes break it down Over months, the piece often looks smaller on a later scan.
- “What if I wait?” gets a real answer Your surgeon can tell you what waiting means for your disc.
After more than 10,000 surgeries, I still want every patient to ask me, and any other surgeon, “What happens if I wait?”
References
- Chiu CC, et al. The probability of spontaneous regression of lumbar herniated disc: a systematic review. Clin Rehabil, 2015
- Xie L, et al. Prevalence, clinical predictors, and mechanisms of resorption in lumbar disc herniation: a systematic review. Orthop Rev (Pavia), 2024
- Haro H, et al. Matrix metalloproteinase-7-dependent release of tumor necrosis factor-alpha in a model of herniated disc resorption. J Clin Invest, 2000
- Benson RT, et al. Conservatively treated massive prolapsed discs: a 7-year follow-up. Ann R Coll Surg Engl, 2010
- Peul WC, et al. Surgery versus prolonged conservative treatment for sciatica. N Engl J Med, 2007
Figure. Herniated lumbar disc, BruceBlaus (Blausen.com staff, 2014), CC BY 3.0, cropped, via Wikimedia Commons.
