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

Spinal canal stenosis is any narrowing of the spinal canal. It is a common condition that has been shown to cause pain to the area, such as back or neck pain. However, due to the pressure that can impinge the spinal cord, it can cause symptoms of pain, weakness, numbness, tingling, and dysfunction to areas distal to the cord compression. While there is no cure for spinal canal stenosis, early detection and treatment can slow the progression and preserve function of vital actions. Canal stenosis is often confused with foraminal stenosis. The word stenosis means abnormal narrowing. Canal or foraminal describe the location of the narrowing, with canal referring to the spinal canal for the spinal cord.

Foraminal refers to the holes on either side of the vertebrae where nerve roots exit. While symptoms may seem to overlap for either type of spinal stenosis, they have different features and distinguishing between the two is important. 

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More About Canal Stenosis

lumbar foraminotomy

The key to understanding canal stenosis is learning the anatomy of the spine. The spine is comprised of 33 vertebrae, the bones that provide the framework and give it the name vertebral column. 9 of these vertebrae are fused into two segments called the sacrum and the coccyx. The remainder are separated in order to allow movement of the spine. There are 7 neck, or cervical, vertebrae, 12 thoracic, or midback, vertebrae, and 5 lumbar, or lower back, vertebrae. The vertebrae are separated by an intervertebral disc that provides cushioning, or “shock-absorption” for the spine. The shape of vertebra allow the spinal cord, which is an extremely fragile, but vital structure, to be encased fully by bone. This bony encasement protects the spinal cord which provides all sensory, motor and organ function for the body upon direction from the brain. Each vertebra has a body in the front, designed to support weight. The spinal cord travels through an opening behind the vertebral body, called the spinal or central canal. The posterior aspect of the vertebra is a bony ring with prominences for muscle, tendon and ligament attachments.

On either side of the ring, a set of joints known as facet joints connect a vertebra to the one above and below it. Because these facets extend above and below the vertebral ring, they provide bony protection of the spinal cord laterally. On either side, a small hole known as a foramen allows a nerve root to exit the spine at each level, forming the nerves that supply our organs and extremities. In total, the spinal canal is formed by vertebral bodies, intervertebral discs, and the components of the neural ring.

What are the symptoms?

Like many problems associated with the spine, canal stenosis has both mild and severe symptoms. This is because it is often a progressive but gradual problem that tends to deteriorate without proper intervention. Canal stenosis pain is very general in the beginning, but often the first symptom noted. This pain can remain localized to the spinal area of involvement, but it also can occur distal to the site of problem. Pain, numbness, tingling in the arms or legs are considered mild, early onset symptoms.

Oftentimes, these symptoms improve with bending forwards, because that position relieves pressure on the spinal cord. This relief is so common, physicians typically ask their stenosis patients, “Is it easier to walk when you push a grocery cart?” The slight forward bend that occurs when pushing a cart often results in less canal stenosis pain. As the condition progresses, more severe signs may involve weakness to the arms or legs, poor balance, loss of bowel or bladder control, and sexual dysfunction.

How is Canal Stenosis 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:

The physical examination is comprised of various components including vital signs, mobility evaluation, visual and palpable assessments. It also includes orthopedic testing to narrow down the causative factors. A neurological assessment is essential in quantifying the impact on the nervous system. This will include things such as deep tendon reflexes, muscle strength and evaluation of sensation. 

•  Medical History:

It is said that 80% of the time a physician will be able to determine a diagnosis simply from the patient history. Probing questions will delve into the type of symptoms occurring currently, as well as past problems. Past medical information and family history will all be considered during the patient history. 

•  Diagnostic Testing:

The gold-standard currently for diagnosing spinal canal stenosis is an MRI. X-rays are typically performed first and demonstrate the bony signs of stenosis. Because stenosis can involve the bony structures as well as the soft tissues, including ligaments, intervertebral discs, spinal cord and nerves, an x-ray is not as conclusive as an MRI. When an MRI is unable to be performed, a CT scan may be considered. Finally, in circumstances which involve potential nerve damage, specific tests such as an EMG (Electomyography) or NCS (Nerve Conduction Study) may be necessary to identify and quantify neurological compromise.

What Causes Canal Stenosis? 

low back pain

Spinal canal stenosis is most often a progressive, degenerative condition occurring after the age of 50. The causes of canal stenosis typically fall in the following categories: 

  • Degenerative: Bone spurs, degenerative intervertebral discs, and other arthritic changes.
  • Inflammatory Arthritis: Rheumatoid arthritis, psoariatic arthritis and others.
  • Congenital: The spinal canal dimensions are too narrow since birth.
  • Spinal Instability: Spondylolisthesis (one vertebra slips forward on another vertebra).
  • Trauma or Injury: Spinal dislocations and burst fractures.
  • Tumors: Either in bone or the soft tissue, tumors may limit canal space.

How is Canal Stenosis 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!

What Equipment is Used to Diagnose and Treat Canal Stenosis? 

While the patient history may be the most important aspect in determining what may be causing symptoms, a spinal physician will utilize simple tools during the physical examination. Reflex hammer, a neurological hammer, tuning fork and pinwheel may be utilized. All diagnostic studies require sophisticated equipment. A physician may have x-ray equipment in office, or at least be able to acquire an x-ray promptly. An MRI typically is only available in large physician offices and hospitals. Many insurances require a pre-certification for MRI testing, usually requiring more than one week to complete. Diagnostic nerve testing requires advanced machinery as well as a specialized physician to interpret. These tests may require additional time to complete.

Treatment equipment ranges again from simple to complex. Exercise equipment may include a treadmill or stationary/recumbent bicycle. Physical therapists, chiropractors and hospital systems will have traction and decompression therapy options requiring computerized machinery to help relieve spinal canal pressure. Surgical intervention is performed at the hospital with the severity of the surgery dictating the length of hospital stay.

How Does Canal Stenosis Compare to Other Spinal Conditions?

Spinal canal stenosis is often confused with foraminal stenosis. Both include narrowing of essential canals within the spinal column. Canal stenosis impacts the spinal cord, while foraminal stenosis affects the nerve root. Both etiologies are typically progressive and can have serious signs and symptoms. However, canal stenosis tends to have more life altering complications if left unchecked.

With early, localized symptoms, canal stenosis can be confused with most other spinal problems. As its symptoms increase and cause greater degrees of impact, spinal canal stenosis is easily discerned from other conditions by the type of functional impact seen. As always, nothing can replace the thorough evaluation obtained from a spinal specialist. After a complete assessment, that physician will be able to tailor recommendations and treatments to the individual patient, ensuring best possible outcomes.

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. Canal stenosis 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.

Good Tunnel

Bad Tunnel

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