A herniated disc and a painful disc are two different problems.

PRP FOR A HERNIATED OR BULGING DISC

Most people arriving with a disc herniation on a scan want to know whether an injection can fix it. The honest answer depends entirely on which of two quite different problems you have, and the scan alone will not tell you.

The distinction that decides everything

A herniation compressing a nerve root produces radicular pain — pain that travels down the leg in a recognizable distribution, often with numbness, sometimes with weakness. The disc is where the trouble started, but the pain generator is a compressed and chemically irritated nerve. That is a nerve problem.

Discogenic pain is different. The pain sits in the back itself, is worse with sitting, flexion and load, and does not travel in a nerve distribution. Here the disc itself is the pain generator, through an annulus that has torn and been colonized by nerve fibers growing inward.

These need different treatments, and the most common error in this area is to treat the second as though it were the first, or to treat a picture rather than a person. There is more on that on PRP for the disc, which covers discogenic pain in detail.

Why the scan is the least reliable part

This is where the disc differs from every other structure on this website, and it is worth stating plainly: disc abnormalities are extremely common in people with no pain at all. Bulges, protrusions and annular tears appear on imaging of asymptomatic adults at rates that climb steadily with age. By the sixth decade the majority of pain-free people have something a radiologist will describe.

So a report saying “L4-5 disc bulge with annular fissure” is not a diagnosis. It is a description of a disc that belongs to somebody your age. Whether that disc is the source of your pain is a clinical question answered by examination and, where it matters, by a diagnostic block — not by the strength of the adjective in the report.

What we will not do

Where a fragment is physically compressing a nerve root, no injectate resolves that. Growth factors do not retract a herniation off a nerve. Anyone offering to treat a compressive herniation biologically is selling something, and we will say so rather than take the booking.

Three findings stop this conversation entirely and start a surgical one, promptly:

• Progressive weakness — a foot that is getting harder to lift, a leg giving way.
• Bowel or bladder change, or saddle numbness — this is an emergency, today rather than after a course of injections.
• A dense, worsening neurological deficit in a specific root distribution.

None of those are reasons to be careful. They are reasons to be somewhere else.

What is genuinely being investigated

Two distinct things get called “PRP for a disc” and conflating them is how expectations go wrong.

Intradiscal injection places the preparation into the disc itself, targeting the degenerate environment in a disc that is the established pain generator. A double-blind randomized trial of intradiscal PRP in discogenic low back pain reported improvement over control, and the subsequent evidence has been positive but modest, from small trials, with heterogeneous preparations. Recent evidence-based guidelines for regenerative therapies in spine treat it as an option in carefully selected patients rather than an established one.

Epidural PRP places it around an irritated nerve root rather than in the disc, and is emerging as a comparator to epidural steroid in lumbar disc herniation with radicular pain. This is a different intervention with a different target, and where we use a preparation near a nerve it is platelet lysate rather than standard PRP — for reasons of what is physically delivered against neural tissue, which that page explains.

The two things you can change while this settles

Most herniations improve without an operation, and the waiting is easier to do when there is something to do during it. Two exposures are worth acting on, and one caveat has to come with them.

Pooling 20 Mendelian randomization studies — a design that uses genetic variants as proxies for lifelong exposure and so gets closer to causation than ordinary observational work — smoking initiation carried an odds ratio of 1.22 (95% CI 1.12 to 1.33) for intervertebral disc degeneration, and body mass index 1.26 (1.14 to 1.38). Nicotine is the more urgent of the two: it constricts the small vessels feeding the vertebral endplate, and the endplate is the disc’s only supply line.

The caveat, stated rather than buried: those are figures for disc degeneration, not for whether a herniation resorbs. We have not seen evidence that quitting shrinks an extrusion, and we are not going to imply it. What the numbers support is the condition of the disc you will still have after this episode resolves — and given that the strongest predictor of a disc problem is having had one, that is not a small thing. The wider version is on the discogenic pain page.

The rule that governs the spine here

Nothing on this site is more strictly gated than the spine, and the reason is that spinal procedures are easy to sell and hard to evaluate. We do not inject a level until something has told us it is the right level. Not a scan. A provocation response, a diagnostic block, or a clinical picture that is unambiguous.

That single rule removes most of the people who arrive asking for this, and it removes them before they have paid for anything. It is set out in full on the spine and sacroiliac joint. Declining is not a lesser outcome than treating; it is frequently the correct one.

Where the answer is not an injection at all

A large proportion of disc herniations resorb on their own over months, and the natural history for radicular pain from a contained herniation is genuinely favorable. Time, a proper loading and behavioral program, and control of the metabolic terrain do more for that population than anything injected.

That last point is not filler. Insulin resistance and metabolic inflammation degrade the disc environment directly, and a disc failing in that terrain will keep failing whatever is put into it. Where the terrain is the problem, treating the terrain is the treatment.

What people ask about a disc on a scan

Can PRP shrink my herniation?

No. Nothing injected retracts a fragment off a nerve. If the herniation is compressing a root and causing progressive symptoms, that is a surgical question. If it is contained and the pain is in your back rather than your leg, that is a different conversation and a possible one.

The mechanism is covered in A disc that hurts and a disc that looks bad are not the same disc.

My scan says bulging disc at three levels. Which one is causing it?

Very often none of them, and that is the honest answer. Multi-level degenerative change is close to universal past middle age. The useful question is not which level looks worst but which level, if any, reproduces your pain — and that takes an examination and sometimes a block to establish.

That is the subject of We do not inject a level until a block has told us it is the right one.

Is a bulging disc the same as a herniated disc?

Not quite, though the words get used interchangeably in reports and conversation. A bulge is a broad, symmetrical extension of the disc margin; a herniation is a focal displacement of material. Practically, what matters far more than the noun is whether anything is being compressed and whether the disc is generating pain on its own.

This is set out in A disc that hurts and a disc that looks bad are not the same disc.

I had a discectomy and the pain came back. Is this for me?

Possibly, but the first job is working out what is generating pain now, which is frequently not what was operated on. That whole problem is the subject of persistent pain after spine surgery, and it starts with taking the problem apart rather than treating the scar.

Related reading

• PRP for the disc
• Spine and the sacroiliac joint
• Platelet lysate — what we use near a nerve
• Still in pain after back surgery
• PRP for the facet joints
• Metabolic health and tissue repair