So you have a disc bulge in your back…
What does this mean?
Let’s go through some anatomy first. Your spine is comprised of a few different levels to include the Cervical (neck), Thoracic (mid back), Lumbar (low back) and Sacral (pelvic/tailbone).
We will concentrate on the Lumbar, or low back area, in this particular blog.
There are five segments, or levels, that make up the Lumbar spine. From the top down, they are numbered 1 – 5. Each spinal segment is comprised of a vertebral body with a corresponding disc in between those two vertebrae. Exiting off of the spinal cord at each level will be a pair of nerve roots which eventually form the nerves that innervate the muscles of your lower body. The openings that these nerves pass through as they exit from the spine are called the foramen. There is a foramen on each side and at each level of the spine.
The disc is comprised of an outer area called the annulus. The annulus consists of several concentric rings of fibrocartilage that encompasses the inner portion called the nucleus pulposa. The disc essentially acts as a shock absorber for the spine.
By definition the following diagnoses are the most involved progression of discal pathology. (See diagrams below for anatomy)
- Bulging Disc: A disc that extends out past its normal position. On an MRI these often look like a tire that is going flat.
- Disc Herniation / Protrusion: The inner portion of the disc (nucleus) is pushing out through the outer layers, but is still retained to within the disc. These often look like a bubble sticking out from the disc.
- Disc Extrusion / Prolapse: A progression of the previous Disc Herniation / Protrusion where the inner disc material (nucleus) actually physically exits through the outer rings of the disc almost as if it was squirted out of the disc like a jelly doughnut.
As diagnoses, there is typically a progression with the above disc pathologies in regards to the severity of symptoms. In each of these pathologies they can vary from quite mild to rather significant/severe in their nature. As a general rule the more significant the pathology, the more severe, (or significant) the potential symptoms.
- Disc Bulges are most often asymptomatic and quite normal within the general population. In severe cases, they can have an effect on the spinal cord or the nerve roots at times.
- Disc Herniations / Protrusions are more significant, but can, at times, be asymptomatic as well. Typically, there can be mild to severe symptoms in the back and into the legs.
- Disc Extrusions / Prolapses are typically the most significant, often causing more severe pains and leg symptoms than a disc protrusion.
Now that we have a little background in the area of anatomy we can talk about what these definitions mean to you and your Physical Therapist.
With a good patient history along with a careful physical examination, your Physical Therapist should be able to gain a good prospective as to what is going on with your spine in regards to not only the amount of pathology, but also to which levels of the spine are involved.
As a note, humans and their anatomy can be wildly variable from one individual to the next. Likewise, how an individual responds to pain and injury is quite variable as well.
From my experience, I have seen patients with very minimal pathology in the spine who, have had significant pain and other symptoms. Conversely, I have seen individuals with a great amount of damage to the spine that are very minimally affected.
As a note on the variation in an individual’s anatomy and their response to the potential pathology at hand, I would like to speak on imaging of the spine. In particular, I would like to talk about the limitations of MRI’s (Magnetic Resonance Imaging).
The MRI is often considered the most telling diagnostic test in regards to looking at one’s anatomy. In particular, it is very good at seeing soft tissue such as discs and nerves. With the skyrocketing costs of health care MRI’s have come under more and more scrutiny due to the shear number of MRI’s performed, their cost, and the frequent lack of conclusive results.
A recent study was published in the New England Journal of Medicine titled “Magnetic Resonance Imaging of the Lumbar Spine in People without Back Pain”.
Jensen et al had collected 98 subjects for this study, all of which reported having zero low back pain.
They performed MRI’s on these 98 individuals and came out with rather astonishing findings.
- Only 36% of the 98 individuals were considered to have a normal spine.
- 52% had at least one disc bulge.
- 27% had at least one disc protrusion.
- 1 % had a disc extrusion.
So, this begs the question, whose spine is actually normal? The answer is, probably very few of us. This is why it is important to realize that MRI’s can be very useful, particularly in finding abnormal anatomy in one’s spine. But an MRI is limited in the fact that it is just a snap shot in time. It is only a still picture of anatomy. An MRI does not always qualify or quantify one’s symptoms.
With so many people (even those of us without back pain) having some amount of pathology in the spine, your Physical Therapist becomes quite important in determining which pathologies in the individual’s spine may be the significant culprit. With this, your PT should be able to educate you and get you on the road to recovery from this injury while decreasing the likelihood of you having another episode in the future.
Kelly Jorschumb MPT, CSCS
Spine Specialist
Site Manager, Cloverdale/McMillan Clinic
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