A 28 year old man working in a corporate job came to me with pain running from his glutes down to his heel. He also had numbness, weakness on one side, and tingling when he sat for a long time. His MRI showed a disc bulge at L4-L5 and L5-S1. He, like most people who see that report, assumed the disc was the cause.
My assessment did not point to the disc. Sciatica vs disc bulge is a question I now get asked almost every week, because MRI scans are so easy to get done, and the report does not always show what is actually causing the pain.
Is sciatica the same as a disc bulge?
No, and this is the most important point in this post. A disc bulge is a structural finding. It is something a scan shows. Sciatica is a clinical symptom. It is something you feel.
Sciatica means the nerve is involved. The pain typically travels from the lower back or glutes down the leg, and it often comes with nerve features such as tingling, numbness or weakness. A disc bulge can cause that. But a person can have a disc bulge and no sciatica at all, and a person can have sciatica without any disc bulge.
Why does an MRI disc bulge not always explain sciatica?
Because disc bulges are common, including in people with no pain. A systematic review of 33 studies of people with no back pain found disc bulges in about 30 percent of 20 year olds, rising to about 84 percent by age 80.
So when a scan shows a bulge at L4-L5 or L5-S1, it tells you the bulge exists. It does not tell you that the bulge is the reason your leg hurts. That has to be worked out by examining you.
How do you find out if sciatica is coming from the disc?
No single test or scan can settle it, so I do not rely on one. I put together several things:
- Your history: where the pain starts, where it travels, and what brings it on.
- Repeated movements, to see whether the symptoms move towards the back (centralise) or further down the leg (peripheralise).
- Straight leg raise and slump tests, which put the nerve under tension.
- A functional assessment of how you move and what loads your back during the day.
- A screen of the hip, because hip pain can mimic sciatica.
If the nerve is really being irritated by the disc, these findings usually line up. If they do not line up with the MRI, the MRI is not the full answer.
What was actually causing his leg pain?
In his case, the straight leg raise and the slump test were both negative. His symptoms were not behaving like a disc pressing on a nerve. His tingling also came on when he sat for long stretches, which told me to look hard at how he was sitting.
What I found instead was how he spent his day. He sat for 8 to 10 hours at work. His glutes were weak. His hamstrings, calves, back muscles and core were tight or not working well together. Even his chair was part of the story, because it was too low for him.
His symptoms were real, and they travelled down the leg. But the driver was his sitting posture and the muscles coping with it, not the bulge on his scan.
How long did his sciatica take to settle?
About five to six weeks. We worked on strengthening, mobilisation, TENS (transcutaneous electrical nerve stimulation), and changes to his posture and daily habits. We also raised his chair to the right height, and he noticed a clear difference after that.
By the end of those weeks he could do all his activities without pain. That does not mean it was finished. He still keeps up the strengthening and takes breaks while sitting, because the cause was a daily habit and it comes back if the habit does.
That was his timeline. It depends on the person and on what the assessment finds, so please treat it as one example, not a promise.
What to do if your MRI shows a disc bulge and your leg hurts
Numbness, tingling or weakness are reasons to get examined, not to guess. Do not assume the disc is the cause, and do not assume it is not. Ask a few things. Has anyone tested how your nerve responds, with a straight leg raise or slump test, or only looked at the scan? Has anyone checked your hip? Has anyone asked how many hours you sit and what your chair and desk look like?
Some symptoms need urgent medical attention and should not wait for physiotherapy: loss of control of your bladder or bowels, numbness around the groin or inner thighs, or leg weakness that is getting worse. If you have any of these, go to a hospital emergency department. He had none of them.
I see patients with sciatica and back pain from sitting in Saket, South Delhi. If you have a disc bulge on your MRI and want to know whether it is really the cause of your leg pain, WhatsApp me at +91 92893 03555.
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Dr. Manvi Dhyani, PT holds an MPT in Sports Physiotherapy from Jamia Millia Islamia and is a registered physiotherapist with the Delhi Council for Physiotherapy and Occupational Therapy (Reg. TPR-2666). She has worked as a team physiotherapist with the Central Reserve Police Force, completed international field postings with ProHealth Asia across four countries, and served as physiotherapist for India’s national archery team at the 2021 World Archery Youth Championships in Wroclaw, Poland. She practices in Saket, New Delhi.
Dr. Manvi Dhyani is a qualified physiotherapist (MPT Sports Physiotherapy, Jamia Millia Islamia; Registered Physiotherapist, Delhi Council for Physiotherapy and Occupational Therapy, Reg. TPR-2666). The title Dr. is used in accordance with her doctoral-level physiotherapy qualification and does not denote a registered medical practitioner under the NMC Act, 2020. registered medical practitioner under the NMC Act, 2020.