Evaluating A Spine Injury Case
The spinal canal is an open space in which the spinal cord and nerves travel down the spine. I like to think of the canal as a tube. Often, on an MRI, a Radiologist will interpret the study as showing “spinal stenosis”, which means that something is encroaching into the tube, or narrowing the tube.
There are many things that can encroach into the tube and affect the nerves that are traveling inside the tube. One of the more common things is ostephytes, also known as bone spurs. Osteophytes are bony projections that develop along the edges or joints of the vertebrae (i.e. bones) of the spine. Some doctors who I have deposed over the years have opined that the body makes osteophytes to stabilize the vertebrae as we get older. Generally, the main cause of bone spurs is age and arthritis. Osteophytes can encroach into the tube and can pinch a nerve, resulting in back pain and/or radicular symptoms into the lower extremities.
Another common culprit that can encroach into the tube is the disc. Doctors sometimes describe a disc as a jelly donut. The jelly of the donut is the nucleus pulposis, which is surrounded by the donut. The disc acts as a shock absorber between the vertebrae. An abnormal disc is typically described as a bulging disc, protrusion or herniation. I have often found that doctors define those terms differently. Generally speaking, a bulge is “broad-based”, meaning it doesn’t bulge on one side more than the either. I like to think of a bulge as a tire going flat. A bulging disc is commonly caused because of a loss of water content called dessication. This is usually a result of age and wear and tear. Typically, a person will have multiple levels of bulging when suffering from a degenerative condition. On an MRI, the degenerative disc will look darker than a hydrated disc. Depending on its size, a bulge can enter the tube/canal and adversely affect the nerves. Some doctors use bulge and protrusion interchangeably. Others define protrusion as a bulge that is more focal, meaning to one side. A protrusion can also be related to degeneration, but more caution should be used when evaluating a protrusion, as it is often used as evidence of an acute trauma to the spine, especially when the other levels of the spine look relatively normal and/or are not focal. A herniated disc is a break in the donut where the jelly escapes. That is to say, a rupture or tear of the annulus allowing the nucleus pulposis to go into the canal. The escaped material can adversely affect a nerve. A herniated disc is a serious condition and can be associated with trauma, especially if other levels of the spine are relatively normal.
Another term used by doctors in describing the condition of a disc is “annular fissure”. Fissures are cracks in the donut. I have heard doctors describe fissures as cracks on the side of a tire. Fissures are common and a sign of long-term wear and tear. Over time, fissures can rupture causing a herniated disc.
Now that we have talked about things that can encroach into the spinal canal, I want to talk about how those things can affect a nerve. On MRI, a doctor interpreting the study may use terms such as impingement, displacement or abutment. Impingement describes that a nerve is being pinched. Displacement means that a nerve is being pushed out of place. Abutment means that something is resting up against the nerve, but may not be touching it. A nerve that is pinched or displaced can be associated with back pain and radiculopathy. It is important to review the records to determine if the examination findings are consistent with the MRI interpretation, which is why some doctors write “clinical correlation suggested.”