Disc herniation is a broad term describing specific changes in a lumbar disc.
A disc is a soft, rubbery structure locate between the vertebral bodies (bones of the spine). The disc acts as a pad or cushion for the bone. The outer portion of the disc (the annulus fibrosus) is made up of a tough fibrocartilage. The middle section (the nucleus pulposus) composed of water and collagen and has a gelatinous (jelly-like) consistency. (Some people describe the disc structure as resembling a jelly donut.) The disc allows for movement of the vertebral bodies and provides a buffer for compression between the bones. Normally, this system works very well.
Overhead diagram of a lumbar spinal disc
When a disc herniates, however, there has been a tear in the annulus fibrosus, and some of the gelatinous center comes out through the tear. These herniations are described by their size, as follows: bulge (small), protrusion (slightly larger), extrusion (big) and a sequestered fragment (when some of the material has broken off from the disc). Once the disc has left its original anatomical position, the disc itself can be painful, it might irritate a nerve, or it may contribute to narrowing of the spinal canal .
There are two parts to this answer – first, it is quite common to have disc herniations in the lumbar spine. In studies looking at people without back pain, a large percentage have had disc herniations that do not cause their back or leg to hurt.
Second, the term “disc herniations” is very broad. “Herniation” is a good – if broad – term to describe a change in the disc. In many ways, it is as generic as saying you drive “a car”. But that car can be a compact car, a sedan, a station wagon, or a large SUV. The same goes for disc herniations – they can be disc bulges, protrusions, extrusions or sequestered fragments. As they get bigger, they involve more symptoms .
This is an excellent question, and there is a good answer. There are four reasons to seek a surgical solution :
This question was answered in a very elegant study . Patients with different sized herniations (bulges, protrusions, extrusions) were assessed with a CT scan and then followed with MRIs. What they found was that by 6 months to 1 year, herniated disc material had dissolved in many of the cases. The larger the herniation (extrusions), the faster the material was reabsorbed.
Long-term studies have shown that, although surgical intervention may generate a faster initial recovery time, conservative (nonsurgical) outcomes are equally effective in patients after five and 10 years [5, 6].
The nerves that go to the legs come off of the spinal cord. As they come off, they run in the spinal canal and then come out between two of the vertebral bodies. When they are in the canal, they are named by the associated disc level (Lumbar 5 or L5). When the nerves come out the individual levels, they group together to make up named nerves, e.g., the sciatic nerve. It is in the canal that the disc irritates the nerve, sending pain down the leg corresponding to the disc involved and the side of the nerve that it irritates [7, 8].
There are a lot of options for nonsurgical treatment of low back pain. The first is physical therapy. Good physical therapy will allow for the disc to heal and to provide improvements in biomechanics and strength. Recent studies have shown that directed physical therapy is more successful than more random approaches. Often, this is enough.
When the pain is too much to try physical therapy, however, epidural injections can also be very helpful. Epidural injections are safe when compared to more invasive procedures. Complications include bleeding, headaches, infections, and very rarely, injury to a nerve. However, pain reduction can be markedly improved. Studies have shown excellent pain reduction and return to function with the use of epidural injections.
The combination of these two techniques can be the most effective treatment of all – the epidural provides pain reduction and makes the physical therapy that much more successful.