What Is Lateral Recess Stenosis?

Lateral recess stenosis (LRS) is the narrowing of the space within the spinal canal that is located toward the sides. Called the lateral recess, or Lee's entrance, this passageway for nerves is close to the spinal nerve root.

As this type of spinal stenosis worsens, the nerve structures in the lateral recess have less and less clear space around them. Nerves may come in contact with bone, putting pressure on disc material or other tissue, which can cause pain and other symptoms.

Read on to learn more about this area of the spine, how it is affected by lateral recess stenosis, what causes it, and how the condition is diagnosed and treated.

Lateral Recess Anatomy

The lateral recess being close to the spinal nerve root means it is close to the part of a nerve that branches off from the spinal cord and into the bony opening between every two vertebrae. This bony opening is called the intervertebral foramen, or foramen for short.

The lateral recess is defined by very specific boundaries inside the spinal canal, which is the central area that runs the length of the spinal column. These boundaries are known as the lateral recess borders.

Lateral Recess Borders

While it may sound odd, the back of the vertebral body makes up the front border of the lateral recess. This front border, known as the vertebral body, also includes the edge of the vertebral body (the endplate margin), and the outermost part of the intervertebral disc (the disc margin).

The intervertebral disc is the shock-absorbing cushion that is located between pairs of spinal bones.

The second border is the side border of the lateral recess. This boundary is made by a structure called the pedicle. The pedicle is a small piece of bone that emanates off the back of the vertebral body; it is the part of a bony ring that is closest to the vertebral body. This ring of bone is critical to many of the spine's functions.

There are two pedicles at the back of each vertebral body—a right one and a left one.

The lamina sits just past the pedicle. It is located closer to the back of the bony ring than to the vertebral body. The junction between the pedicle and the lamina is critical in defining the side boundary of the lateral recess.

This is because other small pieces of bone that help to either delineate the borders, or at least aid in our ability to accurately visualize the area, stem from this junction. These small, emanating pieces of bone are generally called processes, and each has its own unique identifying name, as well.

For example, near the pedicle, the transverse processes extend out horizontally on either side and provide sites for muscles and ligaments to attach. The transverse processes are also the places on the spinal bones in your thoracic area that connect to ribs.

The pedicles make for great landmarks when looking at an image of a spinal bone and trying to determine what's what. As far as the transverse processes go, the pedicle is located in front, and the lamina is located in the back.

The articular processes are other pieces of bone that emanate from the area between the pedicle and lamina. Articular processes from one spinal bone interdigitate with articular processes of the next, both above and below, forming the facet joint. Altogether, facet joints give the spinal column much of its stability.

One of those particular processes, the superior provides part of the back border of the lateral recess.

The other part of the back border of the lateral recess is provided the ligamentum flavum. Of the numerous ligaments attached to the spine, the ligamentum flavum is the one that connects vertically between the lamina of the spinal bones on the inside of the spinal canal.

The job of the ligamentum flavum is to protect you from disc injury; it does so by keeping you from bending too far forward.

Lateral Recess Stenosis Causes

Age-related changes in bones, facet joints and/or ligaments might cause these structures to in some way occupy, and therefore narrow, space called the lateral recess, as well as the other passageways made by interconnecting spinal bones.

And due to their proximity, these imposing (and generally abnormal) tissues may “bump into” the nearby spinal nerve root and/or spinal cord that normally pass through the lateral recess unimpeded.

This is called encroachment or impingement. When encroachment occurs, it may cause pronounced pain and other symptoms.

Lateral recess spinal stenosis is also known as foraminal stenosis. That's because the condition occurs when one or more of the intervertebral foramen narrows and compresses or pinches the nerve roots within it.

Symptoms of Lateral Recess Stenosis

Lateral recess spinal stenosis symptoms may include:

• Radiating lower back pain
• Claudication (cramping that occurs when you walk)
• Weakness and numbness and/or electrical sensations that go down one leg or arm

In some cases, more serious symptoms that disrupt bowel or bladder may occur, as well.

Because the lateral recess is part of the spinal canal, when stenosis develops there, it is categorized as a central canal stenosis. In this case, myelopathy symptoms may ensue. Myelopathy symptoms result from irritation or compression of the spinal cord.

As an example, the development of lateral recess stenosis may occur when age-related changes in the ligamentum flavum occurs. Such changes may include thickening, loss of strength, and loss elasticity to the point where a buckling towards the inside of the spinal canal occurs.

And of course, a thickened ligamentum flavum creates a narrower spinal canal—the hallmark sign of central canal stenosis. If the buckling impinges on the spinal cord, it may cause myelopathy symptoms.

Diagnosis

Diagnosis for lateral spinal stenosis begins with a physical examination, in which your healthcare provider will test your reflexes and look for signs of pain, weakness, and loss of sensation.

Should your provider suspect a spinal abnormality, they may order an X-ray of your spine. The X-ray will show if there are bone growths (spurs) that are pushing on your spinal canal or causing it to narrow.

To help your provider confirm their diagnosis, they will likely order magnetic resonance imaging (MRI), or a computed tomography scan (CT scan). These imaging tests will give them a more detailed look at your spinal canal and nerves.

The combination of a physical exam and imaging tests are often sufficient to make a diagnosis. Sometimes, a healthcare provider will order other studies to confirm their diagnosis, such as a:

• Myelogram, in which you will be injected with a dye that makes your spinal structures stand out better during a CT scan
• Bone scan, to check for fractures, arthritis, tumors, and infections
• Electromyography (EMG), in which electrode stickers are attached to your skin to measure the speed and strength of your spinal nerve signals

Lateral Recess Stenosis Treatment

There is no cure for lateral recess spinal stenosis, nor can the condition be slowed. However, there are lateral stenosis recess treatments and therapies that can help relieve symptoms.

The goals of treatment include:

• Easing pain and inflammation
• Maintaining and improving mobility and flexibility
• Relieving pressure off of the spinal nerves

In some cases, a person with spinal stenosis will have no symptoms, in which case their healthcare provider may take a watch-and-wait approach to their care by monitoring their condition and making routine follow-up appointments.

Medications

For people who do present with pain, healthcare providers can prescribe medications, such as:

• Pain relievers, such as prescription strength ibuprofen (Advil, Motrin), naproxen (Aleve), and acetaminophen (Tylenol)
• Tricyclic antidepressants, such as amitriptyline, which can help ease chronic pain by calming nerve signals that trigger pain
• Anti-seizure drugs, such as gabapentin (Neurontin), and pregabalin (Lyrica), which reduce pain caused by damaged nerves
• Opioids, such as oxycodone (Oxycontin), and hydrocodone (Vicodin) can be prescribed for short-term pain relief. Your healthcare provider may not prescribe them for long-term pain, however, as they can be habit-forming.

Steroid Injections

Corticosteroid injections will not fix the spinal stenosis, but can be given to ease pain and inflammation. The steroid medication may be injected into the neck, mid-back, or lower back/buttocks, depending on where the pain is centered.

Physical Therapy

In an effort to avoid pain, some people with lateral recess avoid physical activity. Doing so does not actually help with symptoms, though, as the lack of activity only tends to increase weakness, and subsequently, pain.

Physical therapy is therefore recommended for any person with lateral recess spinal stenosis, regardless of the severity of their symptoms. Your physical therapist will work with you to maintain and improve strength and mobility in a safe way with lateral stenosis recess exercises and stretches.

For example, you may learn how to avoid exercises done in a standing position, which can increase pressure on your compressed spinal nerve(s). Instead, your physical therapist will show you how to stretch while lying down.

Physical therapy will also help you improve your balance to protect you from falling, and improve the stability of your spine.

Surgery

Finally, if non-surgical treatments are not effective enough to relieve pain or if you are disabled by your symptoms, your healthcare provider may recommend a surgical procedure to relieve pressure on your spinal cord and nerves.

The main surgical option for foraminal stenosis is foraminotomy, in which the area around the affected bone in your spinal column is enlarged to make space for the compressed nerves and take pressure off of them.

For this procedure, a surgeon will make an incision in your back or neck to expose the affected vertebrae. They will then widen the intravertebral foramen and remove any blockages that are compressing nerves.