What is Herniated Nucleus Pulposus?
Written by Neil Badlani, M.D., Chief Medical Officer, North American Spine

Herniated Nucleus Pulposus is a condition in which there is a prolapse of an intervertebral disk through a rip that has occurred in the annulus fibrosus in the spine. The annulus fibrosus surrounds each intervertebral disk, and it’s designed to absorb all of the impact that our spine receives. Typically, a problem occurs with the gel-like disk that is present between the spinal bones. An intervertebral disk is responsible for acting as a shock absorber between each of the vertebrae in the spinal column. The disk keeps each vertebrae of the spinal cord separated when there’s an impact from activity. Furthermore, the intervertebral disk is responsible for protecting the nerves that are present in the middle of the spine and intervertebral disks. 

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More About Herniated Nucleus Pulposus

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The outer layer of the annulus fibrosus is also affected negatively as you age, and the material deteriorates or rips. As the annulus fibrosus rips, back pain is caused for the individual. Not only this, but since the annulus fibrosus is torn, the intervertebral disk now has the ability to shift and prolapse into the tear. Whe this occurs, the condition is then called Herniated Nucleus Pulposus. Other than aging, herniated disks can rupture because of too much pressure all at once. Too much pressure on a disk can force the intervertebral disk to rupture because the annulus fibrosus isn’t able to withstand the amount of pressure that’s being forced onto the spine. Additionally, a disk can rupture from a small amount of pressure, which occurs because of too many injuries repeatedly occurring over time. 

What are the symptoms?

Most of the symptoms actually come from the nucleus pulposus compressing a nerve in the spinal cord. The symptoms caused by the spinal cord compression include: 

  • Chronic pain near your spine: The nerve compression may not give you the ability to localize the pain, but there will be pain on your spine from the compressed nerve. 
  • Numbness or tingling in your legs 
    Since the spinal cord contains the nerve roots that control your sense of touch, you may find that some areas of your legs are numb or tingling. 
  • Pain that radiates in your legs: Since the nerve root in your spine is compressed, you may feel pain in some areas of your legs. This pain may come suddenly and it may cover a large area of your legs, or the pain may come in waves and affect a large portion of your legs. 
  • Loss of fine motor skills:Your nerve root compression may cause your motor skills to suspend from working, and this may result in loss of reflexes in some parts of your legs.
  • Muscle weakness in some areas of your legs: You may experience some muscles in your legs becoming weak, or it may only affect one of your legs. This may result in difficulty walking, since your spinal cord may be compressing the nerves required to move your legs.

How is Herniated Nucleus Pulposus 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:

Your doctor will complete a physical exam, which will include a series of diagnostic tests. These tests may include blood tests, x-rays, a discography, an MRI, and a CT scan. These tests give your doctor the ability to view your spine more accurately. By assessing your spine, your doctor will be able to see what exactly is compressing your nerve root and possibly what caused the rupture to occur. 

•  Medical History:

To diagnose Herniated Nucleus Pulposus, your doctor will first ask you questions in order to assess your medical history. These questions range from asking if you have pain and where it’s located, and then you’ll be asked if you have experienced any muscle weakness or numbness. You may also be asked if you have experienced any pain like this in the past.

•  Diagnostic Imaging:

An MRI or a CT scan are the most popular methods used by a physician to diagnose whether you have Herniated Nucleus Pulposus or not. An MRI is defined as Magnetic Response Imaging, and it’s a test that uses strong magnetic fields to put together images of the organs in your body. This is a popular method for testing because it doesn’t use radiation to produce results. On the other hand, a CT scan is classified as Computed Tomography, and it uses computed X-ray measurements that have been taken from different angles to produce images of specific areas of a scanned object. Both an MRI as well as a CT scan have the ability to identify the cause as well as the precise location of a lesion in the spine.

What are the Causes of Herniated Nucleus Pulposus?

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Herniated Nucleus Pulposus occurs when the gel-like nucleus pulposus of an intervertebral disc comes through a tear that has occurred in the annulus fibrosus and into the spinal column. HNP can occur in multiple different ways and some of the causes include:

  • Aging: As we grow older, our backs and spines experience continued stress and pressure over time from constantly withstanding the weight of our bodies. This essentially causes the intervertebral disks to degenerate over time, and they become more susceptible to damages.
  • Overextension: A herniated disk can occur from overextension. You can overextend your intervertebral disks from bending in a certain way, bending and attempting to lift something that’s too heavy, or from continually lifting heavy objects. Intervertebral disks can also rupture from different amounts of pressure being acted upon the disk.

How are Herniated Nucleus Pulposus 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.


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 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.


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 Herniated Nucleus Pulposus

Equipment that’s used to diagnose HNP varies from different machines used for testing and image-processing. For instance, an MRI and a CT scan are the most commonly-used equipment. Other than this, a myelogram and an electromyogram are used to diagnose HNP. An MRI machine uses radio waves to create images of our body’s internal structures. A CT scan uses a series of x-rays from different directions and combines them to create images of your spinal column. For a myelogram test, a dye is injected into your spinal fluid and shows either pressure on your spinal cord or nerves. And an electromyogram is used to measure how well electrical impulses are moving along your spinal cord, which shows the exact location of the nerve damage. 

Other than this technology, x-rays are also sometimes used to treat HNP because they’re often needed during the surgical treatment of the removal of the herniated disk. They’re used so that the surgeon can see exactly where the vertebrae are in your spine. Lastly, needles are also used for the treatment of Herniated Nucleus Pulposus because they’re used to inject either corticosteroid medication or to inject epidural steroid medication in order to treat the pain that comes from HNP. 


How Does Herniated Nucleus Pulposus Compare to Other Spine Conditions?

There are multiple medical conditions that are similar to Herniated Nucleus Pulposus, such as Osteoporosis, Degenerative Disk Disease, SI Joint Pain, Compression Fracture, and Osteoarthritis.

  • Osteoporosis is a condition in which the bones become weak, which occurs when new bone growth is unable to keep up with replacing the wear down of old bones. Most patients that have Osteoporosis don’t experience any symptoms until they have a bone fracture. This condition can be treated by methods similar to HNP, like a healthy diet, weight-bearing exercise, and medications.

  • Degenerative Disk Disease is classified as Osteoarthritis of the spine, which creates pain in the lower back. This condition can be treated with methods similar to that of HNP, such as exercise, physical therapy, and medications.

  • Osteoarthritis is a condition in which there is inflammation of the joints, causing the flexible tissue at the ends of bones to wear down. This condition can worsen over time if not treated, and it can be treated with medications, physical therapy, and sometimes with surgery. 

  • SI Joint Pain occurs when there is improper movement of the sacroiliac joint. This condition causes pain in your lower back as well as inflammation of the joints. This condition can be treated with methods similar to HNP, like physical therapy and exercise in addition to injections of pain medications.

  • Compression Fracture occurs when the bones of the spine break from trauma. The symptoms of a compression fracture are back pain, weakness, and tingling. It can be treated through methods that are similar to that of HNP, with a back brace, bed rest, exercise, and medications. 

Analogy: Blow-Out vs Flat Tire

A bulging disc is like a flat tire, a herniated nucleus pulposus 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 prolapsed disc (blowout).


Blow-Out = Instant Rupture

Flat Tire

Flat Tire = Slow Leak

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