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

Foraminal narrowing refers to a loss of space, or narrowing, of the foramen, in the spine. To comprehend what this entails, one first must understand the general anatomy of the spine. 

Foraminal narrowing refers to any compromise to the size of the neural foramen. This narrowing is also referred to as stenosis, specifically IVF stenosis, lateral stenosis or foraminal stenosis. It is differentiated from central or canal stenosis which refers to narrowing of the canal where the spinal cord travels. This narrowing can occur in acute circumstances such as a new injury, as well as in a degenerative, or wear-and-tear type of situation. There are established measurements to calculate the size of the opening. Any reduction in size can be classified as narrowing or stenosis, often graded mild, moderate or severe. Infrequently, the canal that develops is naturally smaller than expected. This anatomic difference can compound a stenosis or generate one without injury or deterioration. 

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More About Foraminal Narrowing

lumbar foraminotomyRegardless of the cause, once the tough shell of the disc is weakened or cracked, the soft gel of the nucleus pulposus can deform the disc. Once deformation occurs, the disc may irritate or pinch one or more spinal nerves, causing pain.

Though the two terms are often used interchangeably, there is a subtle difference between a “herniated” disc and a “bulging” disc. On one hand, a herniated disc is a condition in which the tough outer wall of an intervertebral disc has been weakened, allowing the softer insides to deform the shape of the disc. In some cases, a herniated disc will press against the spinal nerves, causing pain. A bulging disc, on the other hand, results when an intervertebral disc, which serves as a cushion between the vertebrae, loses its typical shape and compresses a spinal nerve.

Bulging discs (also called “protruding discs”) have undergone changes in their shape and structural integrity that can lead to spine pain or other problems. Unlike herniated discs, bulging discs have not broken through their outer shell-like casing. Sometimes, a bulging disc and a bone spur occur at the same time. This condition is known as disc osteophyte complex.

If your lower back is hurting, there is a good chance that a bulging or herniated disc may be the cause. Although any one of the intervertebral discs in your spinal column can become damaged, herniated discs are more common in the lumbar region of the spine. This is because the lumbar region supports more weight than other parts of the back. When excess weight is put on this area, there is an increased risk of rupturing a disc.

Whether it’s a herniated or bulging disc, both conditions are easily treated using the same minimally invasive methods. And these methods, whether non-surgical, decompression, or fusion, are certain to have you living a pain free life in a matter of days.

What are the symptoms?

  • Pain, burning, numbness and tingling in neck or back.
  • Loss of muscle strength, mobility or dexterity.
  • Loss of bowel and bladder control.

These symptoms can consist of neck or back pain near the region affected. This pain can occur alone or in conjunction with pain, burning, numbness or tingling to a distant area such as an arm or leg. In addition to the sensory symptoms, compression of the nerve can result in a loss of muscle strength, mobility or dexterity. This dexterity loss can be a difficulty walking or utilizing the fine motor skills of the arms and legs. Foraminal compression of a nerve in the cervical region can cause symptoms to occur in the arms or legs, while stenosis in the lumbar area typically only affects the legs. In severe cases of neural foraminal compromise, bowel and bladder control is affected. This is rare, but is considered a surgical emergency requiring immediate medical care.

How is Foraminal Narrowing Diagnosed? 

In most circumstances, pain or loss of function sends a patient to their physician. This physician will perform the following assessments to evaluate the spine:

•  Physical Examination:

The evaluating physician will ask questions to fully evaluate the nature of the problem. Probing questions are tailored to ensure full comprehension of what the symptoms are, while also identifying the impact of these symptoms. Exploring a recount of the nature of the symptoms, when and how they present, as well as what has been tried to alleviate them will direct the examiner on the next step in the evaluation process. 

•  Symptom Assessment:

A skilled physician will evaluate the spine by quantifying mobility, strength, and coordination as it applies to the impacted areas. Palpation will assess tenderness and muscle tone. Assessment of orthopedic testing coupled with neurologic functional assessments such as deep tendon reflexes and sensation provide vital information regarding the nature and severity of the complaint.

•  Medical History:

An individual’s past medical history will allow thorough assessment of predisposing circumstances such as history of trauma or injury to the area. Risk factors are discussed and evaluated. This may include an exploration of family history.

•  Diagnostic Imaging:

Diagnostic Imaging refers to x-rays, MRI and CT scans that provide pictures of the spinal structures. X-rays are primarily the evaluation of bony structures while an MRI offers the most in-depth visualization of the spine. Diagnostic testing may include neurological tests such as an EMG(Electromyography) or NCS (Nerve Conduction Study). These nerve tests are able to determine the site of nerve compromise as well as quantify the degree of impact.

What Causes Foraminal Narrowing?

low back pain

  • Age-related wear and tear, which can lead to acute processes, such as herniated disc.
  • Arthritis, which causes an overgrowth of bone, bone spurs, and/or ligament thickening.
  • Spondylolisthesis
  • Synovial cysts

While typically diagnosed after the age of 50, there are cases of younger people being diagnosed with foraminal narrowing. In these cases of foraminal stenosis, trauma, congenital spinal deformity or a genetic disease impacting the musculoskeletal system are factors in development of the limited space and impingement upon the nerve root.

How is Foraminal Narrowing 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!

What Equipment is Used to Diagnose and Treat Foraminal Narrowing? 

Diagnosing foraminal narrowing typically requires an x-ray or MRI. X-rays are sufficient in showing the bony narrowing that is impinging the nerve root. An MRI is required to visualize the soft tissues, such as thickened ligaments or cysts, that cause intervertebral foraminal stenosis. In select circumstances when and MRI is unable to be utilized, a CT will offer imaging that includes some soft tissue evaluation. However, if possible, the MRI offers information that is unable to be appreciated on the CT scan. In cases of extreme nerve involvement or progressive symptoms, nerve studies may be required to fully quantify the damage. Tests such as an EMG are typically performed by a neurologist or physiatrist utilizing specialized equipment. 

Treatment options for foraminal narrowing may utilize specialized equipment such as machines that provide manual or automated traction and/or decompression equipment. These are typically found in physical therapy or chiropractic offices and are utilized to decompress the spinal region impacted, without the use of surgical decompression. If spinal injections are recommended, these are performed as an outpatient procedure, under the guidance of continuous fluoroscope which allows the physician to inject directly into the affected region, increasing success rate.

How Does Foraminal Narrowing Compare to Other Conditions Causing Back Pain?

Foraminal narrowing is a progressive impingement syndrome of the spine. It is rare under the age of 50, and in many circumstances the problem continues to decline without appropriate treatment. In the early stages, conservative treatment is extremely successful, especially with localized pain. With more advanced symptomatology, such as numbness or tingling in an arm or leg, conservative options are still very successful at managing symptoms while slowing further decline. Rarely is surgery the first plan of treatment, as symptoms such as bowel or bladder dysfunction are unusual, but considered a surgical emergency should they occur. 

As a progressive problem of the spine, intervertebral foraminal stenosis is often the result of problems sustained years earlier. These problems may have been mild, possibly never even requiring treatment. Trauma or repetitive stress injuries to the intervertebral discs and spinal joints lead to arthritic changes and degeneration, the biggest causes of foraminal narrowing. Previous back or neck pain, diagnosed as a disc injury, a facet joint injury or even a ligament strain, heals in such a way that space is lost to the neural foramen. With progression, symptoms change from localized back or neck pain and begin to impact the legs or arms, causing numbness, tingling and eventually weakness or dexterity loss. This progression underlines the necessity of early diagnosis. When detected early, a long-term plan of care can be established to slow the progression and loss of function.

Analogy: A Tunnel with a Train Track

The nerves of your spine travel like trains on a track. Along their journey, they duck through many enclosed spaces in the vertebrae, like foramen. In order for them to function properly, they must pass through these enclosed spaces cleanly. Foraminal narrowing can collapse some of these spaces like a collapsed tunnel on a train track. If the train of your nerves can’t get through or are pinched by a space that has become too tight, you will feel pain.

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