Risk Factors for Disc Bulges and Degenerative Disc Disease
I’ve been fielding a lot of questions about bulging discs lately. Here are some of the questions I get:
- Can you heal a bulging disc?
- Is a bulging disc hereditary?
- How to treat a bulging disk?
The short answer to the first question is “yes” if the bulge is not severe and the body still has in place the mechanisms to keep the disc living and healthy (see below).
The other answer to the first question is “no” if the disc bulge is the result of breakdown of the nutrient-delivery mechanism to the disc. If this is the case, it is a matter of time before the disc totally degenerates. Physical therapy, chiropractic, spinal decompression and exercises can slow it down, but one cannot do these things indefinitely and often enough to stop the progression.
It’s important to know that your spinal discs are mostly avascular; meaning, don’t have a direct blood supply. Discs get their nutrients (water, oxygen, glucose, minerals, vitamins) via slow absorption from the capillaries directly underneath the vertebral end plates. At the end of the day, your discs flatten from the effects of gravity. As you sleep, they soak up fluids and expand, so that by the time you wake up in the morning you are at least 5 mm taller than when you first went to bed. This is called the diurnal cycle of fluid movement in and out of the disc and is the major means of nutrient delivery.
At the center of the disc is the nucleus, which has tiny cells that make the proteoglycan molecules responsible for attracting and holding onto water. This maintains a hydrostatic pressure that allows the disc to bear about 80% of the weight applied to its spinal level. These cells, similar to chondrocytes that make collagen in the joints, are the most active when the pressure in the disc is about 3 atmospheres. If the pressure is higher (obese individuals, those who carry heavy weight frequently at work) or lower, the cells make less of these molecules, putting the disc at greater risk of drying out. Injuries to the internal part of the disc or vertebral bodies can increase the volume of the nucleus, drastically reducing its hydrostatic pressure and slowing down proteoglycan synthesis. This is one of the pathways of degenerative disc disease, or DDD as the posterior (facet) joints, which are not designed for bearing much weight take on the responsibility of the disc and quickly wear down, forming the familiar osteophytes (bone spurs) seen on X-ray and MRI studies.
Here are the basic risk factors for developing DDD/ bulging discs:
1) History of Structural Damage to the Disc or Vertebra
Single event trauma to the spine resulting in damage to the vertebral end plates . An example would be a parachuter landing hard on the ground on his feet. This can cause a small injury, or even a significant compression fracture to the bony end plates– the surfaces to which the disc attaches. This is bad news, because nutrients to the disc (blood, oxygen, glucose) traverse through these end plates from the top and bottom of the disc. If it is damaged, the area calcifies and “shuts the gate,” depriving the disc of critical nutrients needed to stay healthy. This sets the stage for a slow procession of degeneration over the years which will have phases of back pain, stiffness, disc bulging, stenosis, and in severe cases leg pain, leg weakness and altered sensation.
Repetitive, axial loads to the spine. An axial force is one that travels straight down the spine, while standing. If you are in a job that requires frequent heavy lifting, especially above the shoulders; or requires you to carry 50 or more pounds of gear most of the day, you are placing axial loads on your spine. Similar to #1, it can slowly damage the vertebral end plates and damage the nutrient delivery system to the disc.
2) Hereditary Factors – there are respected studies that strongly suggest a genetic component to DDD. One study showed that there is a 50% greater chance of developing severe disc degeneration in the relatives of past disc surgery patients. Another study found mutations in the genes responsible for the synthesis of proteoglycan molecules, which are responsible for water retention in the disc. If the disc cannot attract and hold onto water, it cannot maintain its hydrostatic pressure. As a result, it loses its ability to distribute weight and slowly dessicates (dries out).
3) Occupation. This is pretty obvious. Those who work with heavy machinery or require heavy lifting are more prone to developing bulging discs.
4) Smoking. Smoking damages the fine blood vessels that the disc depends on to deliver nutrients. It also generates a lot of free radicals, which can damage the disc further. Some surgeons require patients to be “smoke-free” for at least three months prior to surgery.
So, here are the lessons to take here. First, if you have a parent who suffers from bulging discs and degeneration, realize that you have a 50% greater chance of developing them on your own. You may have a mutant gene that is making defective collagen in your disc, making it a ticking time bomb ready to go off in the near future. Your best bet is to minimize the expression of this gene, and a good way to do it is to eat as healthy as you can; ditch the toxins (smoking, excessive alcohol and sugar); avoid getting overweight, and maintain positive thoughts (may affect gene expression to your benefit).
Secondly, avoid unnecessary axial forces to your spine. Stay away from things that involve hard landings on your feet, and don’t lift weights in a way that places pressure to your lower back.
