Pain is a big difference between bulging disc and herniated disc, here’s why

There are many points of difference between bulging disc and herniated disc tissue.  Here is an email that was sent to me wanting to know if two doctors who gave two different diagnoses are saying basically the same thing or greatly different things.

Hello Doctor,

I hope you can clear up something for me about my low back pain diagnosis.

I am 68 years old, a combat veteran, and I have been active in the building trades for the last 22 years.  I am 6 ft all and weight is 220 lbs. I have had a bad lower back for many years and recently made my low back a whole lot worse when I fell off a horse.  So I went to two doctors to find out the best way to take care of my low back pain.  The first one said I had arthritis and a bulging lumbar disc and the second one told me I had a disc herniation. I figure they are both telling me that there is something wrong with the disc in my low back but it sounds like they are not agreeing on what exactly is wrong with me.  Can you explain what is the difference between bulging disc and herniated disc?

E. J.

Greetings E. J.,

The first comment I want to make about your email is for your general information.  You wrote “that there is something wrong with the disc in my back” and that makes it sound like you think there is only one disc in your low back.  If so, you should know that is not true. There are five discs in the low back, and there are 22 discs in the average person’s back that are located between each of the bones or vertebrae of the spine.  (There is no disc between the top two vertebrae of your neck that are located at the base of the skull.)

All discs act as shock absorbers, and they also act as spacers to keep the spinal bones separated from each other, as well as to give the spine flexibility.  Each is generally shaped like a dense but flexible hockey puck, with a soft jelly-like material in the center like a jelly doughnut.  The outer hockey puck part is like a ring that is composed of many layers of tough cartilage that protects and surrounds the softer jelly-like cartilage in the center to keep it in place.  A person gets into trouble when the outer ring of tough cartilage is torn open or wears out as a person gets older, thus allowing the jelly-like cartilage to escape and press on nearby nerves.

Both areas of the disc (outer layer of cartilage and inner jelly-like material) normally have a high water content.  But as we age all discs begin to dry up, causing them to shrink and become brittle.  The disc shrinking causes us to get shorter as we age, since approximately 25% of the total height of the spine is made of disc material, and it also allows the spinal bones to come closer together and this makes nerve pressure and pain easier to occur.  The disc brittleness causes the disc to get injured easier, resulting in tears, ruptures and general thinning of the disc.

With advancing age the damage to the discs accumulates, resulting in loss of the structural integrity of the discs where physical stress is greatest – in the low back – where the result can be either a bulging or herniated disc.

Difference between bulging disc and herniated disc comes down to conditon of the nucleus pulposus to cause low back painA bulging disc is a fairly common problem in the adult population.  When a disc bulges it often does not cause any symptoms.  Problems (pain, stiffness, inability to move, numbness) start  when for any reason a disc swells or extends beyond its normal limit or outside the area it would normally occupy; this swelling is usually broad and diffuse across a large area of the disc.  A disc that is bulging looks like a tire that has too little air in it so that the bottom area swells outward.  The part of the disk that is protruding is due to outward stretching of the tough outer ring of cartilage, but with no change in the inner soft jelly material.  Disc bulging rarely causes pain or other symptoms unless it occurs with spinal stenosis.  Bulging of the disc is a part of the normal aging process of the body that often does not cause pain and is common after the age of 40, and increases greatly with each passing decade.

On the other hand, herniation of the disc in the low back is a more unusual event and often causes lower back pain that can be severe and is often accompanied by leg numbness.  It occurs when a crack or tear in a small specific area of the tough outer ring of cartilage. This abnormal opening allows some of the softer jelly material to escape from the central portion of the disc, causing irritation of the surrounding nerve tissue; when the irritated nerve tissue is a nerve root then pain, weakness and numbness can result.  A herniated disc is sometimes known as a herniated nucleus pulposus, ruptured disc or a slipped disc.

Making it all the more confusing for you and everyone else who is involved in discussing back problems, the sad fact is that there is no specific or universal definition for the terms “herniated disc,”  “bulged disc” or “protruded disc.”  These terms have been studied and polls taken to learn how they are used by spine specialists and statistically it is found that they are used interchangeably.  In this way the terms can be used and can mean different things to different people.  So much for scientific precision.

What is a herniated disc?  Disc herniation or bulged disc

Even though they are using different words, I believe both doctors are basically saying almost the same thing.  I would guess that their only disagreement is a matter of degree and emphasis on what part of your overall problem is giving you the most trouble right now.

Difference between bulging disc and herniated disc

Getting to your question, “What is the difference between bulging disc and herniated disc?”  The difference between a herniated disc and a bulged disc is a matter of the degree of protrusion and apparent injury to the involved disc.

A bulging disc is a smaller protrusion of the central jelly-like material that still retained by the outer ring of the disc. In this case there is less irritation to the nerves to cause pain.

A herniated disc is a more advanced state of a bulged disc that has torn and can no longer keep the jelly-like material within the disc.  In this case there is much more chance fore pressure and chemical irritation to the nerves to cause pain.

My guess is that the first doctor thinks that most of your problem is due to the recent trauma of falling from your horse has aggravated your lumbar arthritis, and that your disc is less involved (only bulged, not herniated) in your pain right now even though it is a part of your current back condition.  On the other hand, the second doctor thinks that most of your problem is due to the fall from the horse causing final and complete disc herniation that is allowing pressure to be placed on low back nerves, and that your spinal arthritis is less involved in your pain right now even though it is a part of your current back condition.

So, what we have to conclude about your original question asking the difference between a bulging disc and a herniated disc comes down to the condition of the jelly-like material.  Most of the time most doctors would agree that a bulged disc is protruding but the jelly-like material is still in the center of the disc.  They would also tend to agree that a herniated disc is protruding but has an opening in it that has allowed the jelly-like material to exit from the center of the disc outward.

Thanks for the interesting question and I hope this helps clear things up for you.

Good luck to you.  DL

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