First, a disclaimer; I am no doctor, but I have talked to many people who are, including chiropractic physicians, neurologists, neurosurgeons, and radiologists. In this piece, I share some of the things these people have taught me over the years.
A "strain" injury occurs where the muscles, ligaments, tendons or other "soft tissues" are stretched beyond their normal anatomical limits. Just think of "soft tissues" as anything but bone tissue. Some physicians will distinguish a strain and a sprain by what was actually stretched or torn, i.e., a tendon or a ligament. Some doctors also classify these injuries on a grading system, ranking them as a Grade I, Grade II, or Grade III, depending on severity, and objective findings. There is a lot of controversy in the medical literature about whether these injuries can result in any permanent impairment. My review of the literature shows that a minority of people with these injuries do in fact suffer long term effects from the injury.
Discs act as cushions between the bones in the spine, also known as the "vertebrae." These joint structures are disc shaped, hence the name, and have a soft center, called a "nucleus pulposis," and described by some doctors as having a crab meat like consistency. The outer edge of the disc is hard and fibrous, and is referred to as the "annulus." The "nucleus pulposus" absorbs water while we are at sleep, and gain height, to better act as a cushion between the back bones. During the day, the force of gravity on the disc presses down on the disc, and it loses some water, and becomes shorter, or "loses disc height." Due to genetics, age, old injuries, or all of these things combined, the discs will slowly wear down, and fill up with less water every night. They become dehydrated, and lose their ability to regain disc heighth on a daily basis. Because the change is gradual, it often does not cause pain.
However, if the disc is subjected to enough force, like being hit from behind in a rear end auto collision, or lifting a heavy box, the outside layer of the disc can tear, and the soft inside material will extrude or herniate out of the disc. This is called a "disc herniation." Doctors disagree on what kind of force causes these injuries, or whether they even happen at all. My experience is that some radiologists are well compensated to opine that disc injuries, whether at work, or in an auto collision, just do not happen. This is generally a unique view among medical professionals.
A disc bulge is different than a herniation. It is where the outer layer of the disc does not tear, but instead, the disc bulges out. Bulges can be from a trauma, like a lifting accident, or a car collision, but they can also result from aging and degeneration of the disc. Then there are annular tears, where the outer layer is torn, but nothing from the center of the disc has leaked or extruded.
Finally, we will often see radiologists pointing out a protrusion. This is just what it sounds like. The disc is protruding out, and is more localized or pointed than a bulge. In our experience, radiologists have gotten a lot more specific about what words they choose to describe these findings when reading an imaging study, usually an MRI.
An MRI, or magnetic resonance imaging, is a picture of the neck, or whatever body part is being studied. The machine uses magnetic fields to get images of not only the bones, but the discs, the ligaments, tendons, and other softer tissues. Some MRI machines take better images than others. Doctors will sometimes interpret the studies differently.
Can a car collision or a lifting injury at work cause any of these findings? It depends on the specific circumstances of the event that caused the injury, sometimes referred to as the "mechanics of injury." It also depends on the interpretation of not only an MRI or x-ray, but other findings that doctors make on examination. Connecting the findings on an MRI and examination findings is called "clinical correlation." Many doctors tell us that in a perfect world, everyone would have an MRI just before they are injured, so that the doctors could compare an MRI after the injury to one before the injury.
If the disc is damaged, it may press up against a nerve root or spinal cord, and that pressure causes problems. The nerve roots branch out from the spinal cord to supply the arms and legs with motor control (movement) and sensation (the ability to feel things, like hot and cold). Symptoms vary, but usually involve some kind of pain or numbness going into the arms. In a severe neck or spine injury, the disc will actually displace the spinal cord, and can cause paralysis.
These happen, but not often. A "burst" fracture may occur as a result of a fall off a roof or scaffolding. In many cases, the treatment for this is bracing. "Compression fractures" occur with falls as well, and people with osteoporosis or other arthritic conditions are more susceptible to this kind of fracture.
Once again, this is just a summary, and there is a whole lot more to this. If you have an auto injury or on the job injury claim involving a neck or disc injury, we offer a lot of experience to help with any questions you have. Call us at 503-325-8600.