Discussion of Annular Tears and Lower Back Pain, Microdiscectomy or Fusion?

///Discussion of Annular Tears and Lower Back Pain, Microdiscectomy or Fusion?

A valuable question and answer session off the Forum (slightly modified)

A: Back pain from an annular tear is common. I assume you have strengthened your core and have had education regarding how to properly lift, bend and load your spine. The next step is an epidural steroid injection. These are generally not a permanent cure but can yield up to a year’s worth of relief. Over time, if the disc becomes more degenerative, it is possible that the disc can stiffen and become less painful. There are individuals who develop IDR (isolated disc resorption) and need surgery but many individuals can improve over time.

I cannot tell you if you need surgery as that issue is somewhat more complex that the information we have shared here. See: When to Have Surgery to understand this issue.

Normally, as the disc degenerates further, the patient will reduce their activity to a tolerable pain level but some patients will continue to have pain that is impairing in spite of activity reduction. Degenerative disc disease is generally a genetic problem so your additional level of L4-5 is not surprising. It may be that this level is not symptomatic and the original L5-S1 level is causing all your pain.

Q: I still have a good amount of pain in my back. Not sure really how it would be relieved. When talking about surgery, are we talking about a discectomy or a fusion? I am just 24, and would not want to have a fusion as it will put more stress on other levels and i might end up having a cascade of surgeries. Would a discectomy help in my case as it is a herniated disc only although it is otherwise quite healthy and not degenerated a lot?

A: If your back pain is more one-sided (unilateral) and on the same side as the herniation, you have a better chance of back pain relief with a microdiscectomy. With unilateral pain on the same side as the herniation, the chances are about 70% for acceptable relief. If the back pain is central in nature, the chances of relief with a microdiscectomy are more like 50%

Q: I have more of a central pain. I am actually very confused here. I see a lot of patients who have leg pain, tingling, etc which means they have an annular tear with a larger herniation which I do not have. I have a herniation, which bothers no nerve. Still i see them doing great after a microdiscectomy, which in my case would have only 50℅ chances in relieving my pain although my condition is not worse as them.

A: That is correct. Surgery for a herniated disc (microdiscectomy) that causes leg pain has a success rate of over 90%. A microdiscectomy surgery for central back pain has a 50% chance of good relief (70% if unilateral pain). The reason is about half the time, the herniation causes tension on the posterior annular fibers, which is painful. Removing the herniation therefore stops the tension of these fibers and relief is gained.

The problem is the other 50% of discogenic pain is pain not due to tension on these annular fibers but due to abnormal mechanical motion of the disc and this pain can only be resolved by fusion. There is no current testing we have to determine if this disc pain is one or the other so you either choose a microdiscectomy with the knowledge you have a 50% chance of relief and then consider a fusion if no relief is gained or consider a fusion initially with a higher chance of success (90%). Or you can try to live with the pain and adjust your lifestyle, as even though this pain is impairing, it is not dangerous.

Q: This kind of goes in line with the research i have done from internet. Please correct me if i am wrong.

When a radial annular tear happens inside out but not tearing the outer layers and nucleus exudes into the layers, it gives a discogenic pain and there is no specific known reason for this pain and body does not have any way to heal it and it always remains the same. But when the tear crosses the outer layers, where there are very sensitive nerve endings, the nucleus that flows out might irritate these nerves and cause inflammation and hence pain. Hence, in a discectomy, the nucleus and the painful torn outer layers are removed and sealed using RF, which gives relief from this inflammation and reduce pain but the internal tear still remain there and discogenic pain still persists. Discectomy only does half of the work essentially.

A: RF is radiofrequency ablation is the use of an electric current to generate heat to “melt” the outer annulus. Through multiple trials, RF has been demonstrated to be ineffective for “sealing” the outer disc.

Q: If i am right here, I have few questions: how good the sealing of the outer layers is done so that there is not a re-herniation again and what’s the rate of the re-herniation after a discectomy?
How bad can a discogenic pain be? And how to deal with it for lifetime, since i am in my youth now? I believe Tylenol is a medicine which works great to reduce its pain, but would it be fine taking it often whenever there is a heavy pain?

A: The rate of re-herniation after a discectomy is about 10-15% in an active population. The disc is avascular (no blood supply) so the disc cannot heal the through and through tear. A scar does form on the outer wall but it is only about 30% as strong as the original annulus. As long as you stay below the maximum daily dosage of Tylenol, you should be OK but if you take it daily, every 6 months a liver function blood test would be helpful.

Q: How does it work in disc bulge, because essentially there is not a tear in the outer layers and nucleus does not flow out, and if there is no nucleus flowing out, it would not cause inflammation on the outer sensitive nerve endings, but still a discectomy is prescribed in a disc bulge, how does discectomy work in a disc bulge?

A: A disc bulge implies that the posterior wall of the disc is protruding out. This means the annular fibers have stretched making them incompetent. Some fibers are torn and others have elongated.

The difference between the two surgical discectomy scenarios (50% vs 70% relief) has to do with whether the pain is generated by the annulus or by nerve root compression. If the pain is one sided (on the side of the herniation), a good percentage of these patients actually have nerve root compression pain that does not radiate down into the buttocks but stays only in the off-midline side of the herniation.

The more the nerve is inflamed due to the size and location of the herniation, the more pain will radiate pain down the root’s pathway toward its terminus. Likewise, when the nerve inflammation is improving, the pain centralizes. That is, the pain recedes up the root to its origin (the side of the lower back at the level of the root). I see this all the time. If however the annulus is stretched causing local central lower back pain, the chance of improvement is only 50% with surgery.

Q: Can you tell me what is the source of the pain coming from annulus? Is it due to the annulus being stretched causes the outer layers to stretch where there is herniation, and that causes pain or is it something else? And is it related to the other 50℅ discogenic pain that we were talking earlier?

A: The annulus is highly innervated with nociceptors (pain fibers). We know this from microscopic work identifying pain nerves in the annulus and with ill-performed discograms, a test used to determine pain generation capacity of the disc.

With a normally performed discogram, a needle is placed in the center of the disc and fluid is forced into the nucleus of the disc through a syringe to pressurize the annular walls, looking for a pain response. If however, the needle is accidentally placed in the annulus (which can happen if the discographer is not accurate with needle placement) there will be reliable lower back pain reproduced every time depressing the syringe plunger pressurizes the annulus.

Most of the pain fibers originate from the outside of the disc wall and enter through the sides. There is also nerve supply that enters through the vertebral body. Interestingly, if there is a tear of this annular wall, pain fibers grow into this tear along with blood vessels and sensitize the disc even more.

Q: This is what microdiscectomy does not fix, right? The discogenic pain that arises due to the nucleus pressure or pressure received on annulus during any activity like running, jogging, biking, travelling in a car. 

A: Microdiscectomy can only fix the pain which is associated with tension of the outer layers of annulus. Removing that portion of disc and cutting some fibers under tension and ablating them relieve tension.

Aberrant motion of the disc is what a microdiscectomy will not fix. The disc is designed to restrict motion, like a bushing. With annular tears, the disc motion initially increases and the disc moves in ways that increase the stress on the more intact but injured annular fibers. This leads to further damage. In some discs, this motion continues to destroy the disc wall and endplates, eventually leading to isolated disc resorption (Isolated Disc Resorption Lumbar Spine (IDR)).

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