What is Disc Extrusion?
Written by Neil Badlani, M.D., Chief Medical Officer, North American Spine

When some of the inner filling of a disc leaks outside of its fibrous outer coating, this is often referred to as a disc extrusion. To understand this concept a little better, it is helpful to know more about spinal discs and what their purpose is in connection with the spine. 

The spine is made up of multiple interlocking bones called vertebrae. These vertebrae are separated by the spinal discs. Discs provide cushioning to prevent the bones from banging together during any type of movement. These discs also keep the vertebrae stable and offer protection to the bundle of nerves that runs down the back. 

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More About Disc Extrusion

lumbar foraminotomy

Each disc is made up of two parts. The outer layer is tough and fibrous. This outer layer is called the annulus fibrosis. In a way, this outer layer resembles a tire. The inner portion of each disc is made up of a soft, jelly-like substance. This center portion of a disc is called the nucleus pulposus. In a healthy disc, the filling stays inside. This can almost be compared to a jelly donut. Through weakening of the outer layer of the disc over time or due to some type of injury, the annulus fibrosis may also weaken, allowing the inner nucleus to protrude beyond its normal position within the center of the disc. This may cause the disc to bulge out a bit at the weakened area. If the outer layer of the disc tears or cracks, the nucleus pulposus can leak out into the surrounding spinal region. While the damage to the outer core may not be as extreme as taking a bite out of that jelly donut, the tear can be enough to allow the gel to ooze out. This is what is called disc extrusion, because the nucleus extrudes out of the disc. 

The material that leaks out of the disc may press on one or more of the nerves running up and down the spinal column. This can lead to a wide rang of symptoms, including back pain. Additionally, disc extrusion can leave a disc flattened, providing less protection to the surrounding vertebrae. This an lead to pain if the vertebrae touch each other during movements. A flattened disc can also lead to spinal instability. It is important to accurately diagnose a disc extrusion so that your physician can provide you with the appropriate treatment.

What are the symptoms?

While extrusion can occur in any disc of the spine, it more commonly occurs in the lower back between the lumbar vertebrae or the neck between the cervical vertebrae. The most common symptoms related to disc extrusion are: 

  • Pain
  • Numbness
  • Tingling
  • Weakness

When it comes to disc extrusion pain symptoms, these may vary widely from person to person. For some, the pain may be more of a minor discomfort. For others, the pain can be severe. The pain may affect your ability to perform your daily activities, especially if certain movements make the pain worse. This pain can be localized or it may radiate to the nearby limbs. 

Other symptoms may include numbness, tingling, or weakness due to pressure on a nearby nerve or nerve complex. Disc extrusion pain, numbness, and other related symptoms are generally experienced on only one side of the body, depending on where the jelly-like nucleus has leaked out.

How is a Bulging Disc Diagnosed?

Pain is the first indicator of a bulging disc that needs attention. Once identified, there are typically four steps to the process

•  Physical Examination:

After getting the history of your issue, you will most likely be given a physical examination. Your physician may check your spine while you are standing up and again while you are lying down. You may be asked to perform specific movements, such as straightening your leg while you are lying on your back. Your physician may also check your reflexes to determine if motor function and sensation are affected.

•  Symptom Assessment:

Your physician will ask you questions about your overall health and your back pain. You may have to answer questions concerning exactly where the pain is located, the severity of the pain, if certain movements increase pain, and if there are any other symptoms that could be related. 

•  Medical History:

As with any kind of disease or condition, diagnosis also needs to take into account the patient’s full medical history. This allows the doctor to figure out if other conditions are causing the pain, and they’ll learn about previous diagnoses, any drugs taken, previous surgeries and other important pieces of information.

•  Diagnostic Imaging:

Other imaging tests that are commonly used to detect abnormalities or changes in a spinal disc are MRI, magnetic resonance imaging, and CT scan, computed tomography. These imaging tests can see damage or changes in soft tissue, such as that of the discs and the nerves in the spinal column. The Radiological Society of North America notes that a discography, or discogram may be used. In this test, a dye is injected to provide better contrast during imaging.

What are the causes of a Disc Extrusion?

low back pain

An injury to the back or spine is one way that a disc can rupture and release its nucleus into the surrounding region. However, the most common cause of disc extrusion is a weakening of the disc that occurs naturally over a period of time. As you age, the discs in your back lose a bit of their water content. As the discs dry out a little, they become flatter and offer less cushioning, increasing your risk of disc damage. Additionally, the pressure of vertebrae pressing on your discs day after day also weakens them. 

Small cracks or chips may occur in the outer layer, though this may not even cause any symptoms. As the outer layer weakens, the inner portion may press outward a bit, making the outer layer move outwards as well, creating a bulge. If the disc damage increased from consistent pressure on the weakened area, it may tear or rupture. This results in disc extrusion.

How is Disc Extrusion treated?

Conservative Options

Conservative treatment options include nerve root blocks and steroid injections. These are designed to provide temporary relief (up to one year), and you may elect to have the procedure done multiple times. Other conservative strategies may include the placement of a spinal cord stimulator–or STIM–which is designed not to correct the underlying degeneration, but to lessen the pain the condition causes.

Decompression

Minimally invasive decompression surgery aims to relieve pressure on the nerves of the spine. This pressure is often caused by stenosis, bulging or herniated discs, and more. Relieving this pressure can be achieved by reducing or removing soft tissue (disc material or scar tissue) or bone (bone spurs, a section of the lamina or foramina) to decompress the affected nerve. When the compression is caused by soft tissue material, a surgical laser may be used to shrink the impinging material.

Fusion/Stabilization

Fusion surgeries are similar in goal–to remove damaged disc tissue and fuse the bones together–but differ in approach, including the use of specialized hardware to reinforce stability, and the location used to gain access to the spine. A related procedure is an artificial disc replacement, in which a damaged cervical disc is replaced with a synthetic disc, and the vertebrae are not fused.

How Much Does Treatment Cost?

Treatment cost depends on several factors, especially what insurance you have and how much of your deductible has been met. IN the last two years, 90% of our patients have paid less than $2000 out-of-pocket. Some have paid literally nothing, and other have paid much more than that. It depends. The good news is: our Patient Care Managers will handle as much as they can directly with your insurance company, and all your costs will be known up-front.

Important note: spine surgery often pays for itself within a year or two. Many people actually spend more money trying to live with the pain than they do getting the pain fixed. The following calculator is intended to give you a sense of what you spend on managing—rather than eradicating—your pain.

 

Calculate how much you've spent on back pain this year.
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This past year you have spent on your pain treatment:

Get surgery now. Getting surgery now is the smartest financial move. Over the last two years, the average North American Spine patient spent around $2,000 out-of-pocket for treatment. You’ve spent that much or more this year to manage your back pain than you could to fix it.

Get surgery soon. Over the last two years, the average North American Spine patient spent around $2,000 out-of-pocket for treatment. At your current rate, you will spend that much or more within the next two years. The sooner you get treatment, the sooner it will pay for itself.

Keep an eye on your spending. Currently, you are managing your pain efficiently from a financial perspective but over time, your expenses could add up. Surgery should be strongly considered if you start missing more work or spending more on treatment medication.

Great job! You are spending very little on your back pain. Keep it up!

Equipment Used in Diagnosis and Treatment of a Bulging Disc

When diagnosing a disc extrusion, equipment that is used may include x-rays, MRI, CT scan, or discography machines. 

If physical therapy is recommended, treatment may include the use of an electrical nerve stimulator or hydrotherapy, which might involve the use of a whirlpool or bath. Mechanical traction may be used if taking pressure off of the affected disc is recommended, either alone or combined with other types of treatment. 

For surgical options, artificial discs or artificial nuclei may be used. If fusion is necessary, a metal interbody cage or pedicle screws may be inserted to help the two vertebrae to fuse together.

 

How Does Bulging Disc Compare to Other Spine Conditions?

There are multiple names that can be used to denote a disc extrusion. There are also a few related conditions that are not exactly a disc extrusion, but they are similar. Some names of conditions you may hear include:

  • Degenerative disc disease
  • Herniated disc
  • Disc protrusion
  • Ruptured disc
  • Collapsed disc
  • Bulging disc
  • Slipped disc
  • Compressed nerve
  • Pinched nerve
  • Sciatica

Some of these conditions are the same, while others are not. Many of these names mean the same thing, while some are just different stages of progression of disc degeneration.

Degenerative disc disease is the mildest form of disc problem. Drying, tiny chips, and shrinkage of the disc may occur. Continued weakening of the outer firm layer of the disc may result in a more serious issue. This is called herniated disc. A herniated disc is a term that is used to notate a shift in the gelatinous center of the disc. This movement of the nucleus can create a bulge in the disc or it may leak out if the outer layer is damaged.

When the nucleus presses outward to create a bulge, this is known as a bulging disc, disc prolapse, or a collapsed disc. The misshapen disc may or may not press on surrounding nerves. When the inner jelly-like substance inside of the disc leaks out, this is what is referred to as disc extrusion, slipped disc, or ruptured disc. This can lead to pressure on surrounding nerves, depending on the amount of nucleus that escapes from within the disc. If some of the soft core becomes completely separated from the rest of the disc, this is called sequestration.

Analogy: Blow-Out vs Flat Tire

A bulging disc is like a flat tire, a slipped disc is like a blowout. When you have a flat tire, the wheel’s material loses its shape, but it stays more or less together. In a blowout, the inside of the wheel becomes exposed to the outside.

Both conditions can cause pain, and both should be professionally evaluated. And don’t forget: a bulging disc (flat tire) can progress to become a slipped disc (blowout).

Blow-Out

Blow-Out = Instant Rupture

Flat Tire

Flat Tire = Slow Leak

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