Spinal Injuries: Herniated Disc vs. Bulging Disc

Sometimes, the terms herniated disc and bulging disc are used interchangeably, leading to the assumption that the two terms refer to the same injury. However, this is not the case. Understanding the differences between the two conditions helps to explain the severity of the central problem, along with the pain associated with such an injury. This ambiguity in the terminology may lead to a feeling of frustration when trying to understand your diagnosis and treatment. Additionally, there are many other terms used for the same conditions, adding to the confusion. Some terms are even used incorrectly, leading one to assume that there is no agreed upon difference.

In addition to herniated and bulging disc, terms, like torn disc, slipped disc, ruptured disc, collapsed disc, disc protrusion, disc disease, and black disc may all further contribute to the confusion [1].

This article will seek to clarify the major differences in these two similar, but very much different, injuries. Before we can understand the difference between a herniated disc and a bulging disc, let’s first take a look at some basic anatomy of the spine.

What is a Spinal Disc?

We can begin by assuming that a spinal disc is just that, a disc, and it is located in the spine. Thankfully, understanding the term spinal disc doesn’t lead to confusion. A spinal disc is a round piece of cartilage that is flat on the top and bottom, very much shaped like a disc.

The spinal discs sit in between each vertebrae—the butterfly-shaped bones that make up the spine—separating each of the bones from each other. Spinal discs play three main roles in the human body: allowing for flexibility of the spine, keeping the vertebrae in-line while protecting the spinal cord, and acting as shock absorbers for the impact the body receives from daily activity [2]. The appropriate medical terminology for what is more generally referred to as a spinal disc (as we are referring to it in this article) is an intervertebral disc [3]. This makes sense because the prefix “inter-“means between. Thus, the term references “between the vertebra discs.

The disc is composed of a gel-like center, called the nucleus pulposus, and a strong, fibrous outer layer, called the annulus fibrosus. For clarification, it may help to think of them as miniature jelly doughnuts, since there is a firm outer layer with a gelatinous inner filling.

Parts of the Spine

The spine is broken into four categories: cervical spine, thoracic spine, lumbar spine, and sacrum.

Cervical Spine- The cervical spine is basically your neck. It begins at the base of your skull and ends at about the shoulder blades. There are seven cervical vertebrae labeled C1 through C7. “C” represent cervical and the numbers represent each bone starting from the skull, down. Easy enough.

Thoracic Spine- The thoracic spine makes up the middle of your back. Most of the thoracic vertebrae are connected to rib bones, making this section relatively stable. There are twelve vertebrae labeled T1 through T12. Again, “T” stands for thoracic and each bone is labeled from the top down.

Lumbar Spine- The lumbar spine makes up your lower back. Many back-related injuries occur in this section. There are generally five vertebrae in this region, but there can be six and some can be fused with the tailbone. These vertebrae are larger and stronger than the others, but also under more pressure. This section of the back is responsible for carrying a majority of the body’s weight.

Sacrum/Coccyx- The sacrum is commonly referred to as the tailbone. It is made up of four or five vertebrae that are fused into one long bone. It is also considered part of the pelvis. 

What happens during a disc injury?

Whether the disc is herniated or bulging, which we will soon cover, it is helpful to first understand what is even being talked about. Terms like slipped disc may give the impression that the actual vertebral disc has slipped out from between the two bones. Other terms are no less confusing. In actuality, the inner gel (nucleus) and the fibrous outside (annulus) are actually being referenced, rather than the whole disc itself. When an injury occurs—regardless of which type mentioned above—the gel lining either pushes into or protrudes through, the outer-layer. The disc itself never moves. It may be helpful to reference the diagram found at the Laser Spine Institute’s website.

According to Dr. Michael Perry from the Laser Spine Institute, a herniated disc is referred to colloquially as a bulging disc, and a slipped disc is often referred to as a ruptured disc. No matter what you call them, these conditions can lead to nerve root irritation, which can cause traveling pain, numbness, tingling, muscle weakness, and other disabling symptoms. We will cover the pain symptoms in more depth later.

In addition to producing similar symptoms, herniated discs and bulging discs have similar root causes. Poor posture, a spinal injury, repetitive spinal strain, or the normal wear and tear of age can lead to either condition [5].

What is the difference between bulging and herniated disc?

A bulging disc is contained, meaning the nucleus has not protruded through the outer layer (annulus fibrosus) of the disc. This is because there is no tear or rupture present within the outer layer which would allow the gel to escape. Instead, there is a small, bubble-like protrusion into the spinal canal. Without said tear, no portion of the nucleus pulposus can leak out of the disc.

A herniated disc is not contained, meaning that a tear or rupture is present. As such, a portion of the gel-like nucleus has leaked into the spinal canal. A herniated disc may have begun as a bulging disc, but it created so much pressure on the outer wall that is caused it to rupture. Because of the obvious progression of the conditions, herniated discs are more likely to cause severe pain, though each can vary by severity and person. Some may even cause no pain at all.

Two Types of Disc Pain

According to Spine-health, both the indication of pain and the use of technology can locate a herniated or bulging disc, which is covered in more detail below. In terms of pain, identifying the cause of a patient’s pain is categorized by two general types: disc pain and a pinched nerve.

General Disc Pain

Disc pain is more accurately called Degenerative Disc Disease, which most often is a result of old age [6]. As a person ages, their spinal discs begins to dry out, creating issues and resulting in pain. With a degenerated discone that causes lower back pain and/or leg pain—it is the disc space itself that is painful and the source of pain. This type of pain is typically called axial pain. This is an indication of degenerative disc disease.

Pinched Nerve Pain

A pinched nerve in the spinal disc—or whichever of the above terms you and your doctor call it— refers to the damaging of the outer hard part (annulus fibrosus) allowing the softer inner part (nucleus pulposus) to protrude through. It basically leaks out. Once this happens, the part of the nucleus that is sticking out comes in contact with and irritates, a nearby nerve. This is what causes sharp back pain. This almost always happens—90% of the time, to be exact—in the lower back. This is why lower back pain is such a common complaint [7]. Most back injuries fall into this second category. Pinched nerves are also called herniated discs, slipped discs, ruptured discs, prolapsed discs, bulging discs, etc. When a patient has a symptomatic herniated disc, the disc itself is not painful, but rather the material that is leaking out of the inside of the disc is pinching or irritating a nearby nerve. This form of pathology produces pain called radicular pain. This leads to pain that may “radiate” to other parts of the body, such as from the lower back down the leg, or from the neck down to the arm. This is formally an indication of a herniated disc.

Symptoms of Herniated and Bulging Discs

The most common signs and symptoms of a herniated disc are:

Arm or leg pain. If your herniated disc is in your lower back, you’ll typically feel the most intense pain in your buttocks, thigh, and calf. It may also involve some parts of the foot. If your herniated disc is in your neck, the pain will typically be most intense in the shoulder and arm. This pain may shoot into your arm or leg when you cough, sneeze, or move your spine into certain positions.

Numbness or tingling. People who have a herniated disc often experience numbness or tingling in the body part served by the affected nerves.

Weakness. Muscles served by the affected nerves tend to weaken. This may cause you to stumble, or impair your ability to lift or hold items.

Common symptoms of a bulging disc:

  • Muscle weakness, numbness, or tingling in one or both legs. This is usually a symptom related to a bulging disc in the thoracic region.
  • Increased reflexes in one or both legs that can cause spasticity.
  • Changes in bladder or bowel function. Spinal pain can cause a host of other issues since the spinal cord is so central to how everything else in your body functions.
  • Pain moving your neck. This is most common with cervical bulging discs.
  • Deep pain near or over your shoulder blade.
  • Radiating pain in your upper arm, forearm, and possibly your fingers. [8];[9]

How is spine pain diagnosed?

These conditions can occur anywhere along the spine: the cervical (neck), the thoracic (upper back), or the lumbar (lower back). In terms of regularity of reoccurring injuries, the lower back bears the most torque and force on a day to day basis, making it the most commonly strained part of the spine.

Doctors will often use the patient’s description of the pain and symptoms to help them begin narrowing their diagnosis. However, there are more precise methods that will help to narrow down the problem.

To find the source of these pains, physicians and claims adjusters will often require an MRI scan or CT scan to further analyze the severity of the issue.

MRI Scans for Disc Injuries

MRI scans or Magnetic Resonance Imaging represent a very sensitive and accurate assessment of spinal anatomy. It is an imaging test that allowed physicians to assess a patient’s spinal anatomy and investigate an anatomical cause of the patient’s back pain. The physicians will be able to correlate the findings on the MRI scan with the patient’s signs and symptoms of back pain in order to arrive at a clinical diagnosis. This correlation is needed because an MRI cannot distinguish between painful and non-painful structures in the spine. In fact, a patient may have severe back pain with an MRI scan that shows a relatively normal-looking spine; or conversely, they may have no back pain at all, but their MRI scan reveals a lot of anatomical problems. Therefore, the findings on MRI scans do not constitute a diagnosis and the MRI findings must be correlated with the patient’s physical exam and back pain symptoms to arrive at a clinical diagnosis.

CT Scans for Disc Injuries

Computerized tomography or CT is a fast and pain-free diagnostic process used when disc rupture, spinal stenosis, or damage to the vertebrae is suspected. To create a CT scan, a type of x-ray machine is used at different angles in order to get multiple images of the back. The x-rays produce two-dimensional slices (1mm each) of internal structures of the back. The images are then combined in order to create a more accurate, 3-D image of the area. Just like the MRI, these scans do not offer a specific diagnosis without a correlation to the patient’s pain and symptoms [10].

It’s important to note that it’s not usually necessary to obtain an MRI scan at the initial onset of spine-related pain, as most cases of back pain will resolve within two to twelve weeks with proper conservative (non-surgical) treatment. Quite often, MRI scans are needed when conservative treatment is not working and more aggressive back pain treatments (i.e. injections or surgery) are contemplated to relieve the symptoms. In terms of personal injuries, however, MRIs or CTs can be the correlation needed to help secure compensation for a victims losses. This is why you need an experienced attorney who knows exactly what to do following an accident and associated back injury.

Other Sources of Disc Pain

Besides herniated and bulging discs, spinal pain can be caused by two other main sources as well: annular tear and fragmented material. In order to provide as close to a complete picture as possible, we will discuss them briefly.

An annular tear is when the fibrous, tough exterior of the disc (annulus fibrosus) is torn [11]. This is very similar to a herniated disc, but there is a distinction. Basically, the annular tear is what allows a disc to herniate. It could be thought of as the annular tear occurring and then the gel-like nucleus can escape. When someone has annular tear pain—or their MRI or doctor mentions it—it is usually because the injury stands alone as the cause of the pain. Meaning, the disc is torn, but the nucleus is not protruding or leaking. If it was, the annular tear part is not mentioned, mostly because it is a given.

Sequestration or Sequestered Disc (sometimes called fragmented disc material) is when the gel-like inner core (nucleus pulposus) breaks through the tough, fibrous exterior (annulus fibrosus) and lies outside the disc in the spinal canal [12]. Unlike with a bulging or herniated rupture in the exterior of the disc, in a sequestration a piece of the nucleus actually breaks free from the intact core and moves freely. This type of injury usually causes extreme pain due to the close and complete contact the fragment makes with a nerve.

Back Injury Attorneys – Dolman Law Group

If you or a loved one has been injured in an automobile accident, seek medical attention right away. It is imperative that you are examined by a trained medical professional. It is often the case that people are injured in an accident and do not realize it immediately. Clients often mention that they did not notice anything was wrong until days or even weeks later. This is because of a few things. First, your adrenaline begins to pump when you are first in a traumatic accident. Your mind in concerned with any immediate dangers, the severity of the accident, what went wrong, and the safety of those around you. Later, your mind may be focused on the past event and what you are going to do next. As the dormant injury worsens, and the body starts to deal with the trauma, pain may become noticeable. It is at this point you may begin to notice trouble sleeping, walking, and getting out of bed or a seat. You may start to notice radiating pain or trouble moving your body in a normal, pain-free way. This is why it is imperative you seek medical help immediately.

Once your safety is secured, contact an experienced law firm. At the Dolman Law Group, we have spent years specifically handling personal injury cases with a focus on spinal injuries. We have the expertise and resources to handle any case, no matter how complicated. Waiting to see if your injuries progress or how your insurance company will handle the medical bills, is never the way to go. Injuries of this severity rarely rectify themselves and for-profit insurance companies rarely pay for all expenses. It is your right to be compensated for damages caused by someone else’s negligence. This is precisely why such laws exist.

If you need our help, please don’t hesitate to contact us. We will be glad to meet with you for a no cost consultation. We look forward to hearing from you.

Dolman Law Group
5435 Main Street
New Port Richey, FL 34652
(727) 853-6275


More information on spinal issues:

Other disc injuries

Sacroiliac Join Paint and Sciatica

Spinal Fractures