WHAT YOU NEED TO KNOW ABOUT SCIATICA

Taken from our 25 July 14 Spine-Health Powered Newsletter

The term sciatica describes the symptoms of leg pain and possibly tingling, numbness or weakness that originates in the lower back and travels through the buttock and down the large sciatic nerve in the back of the leg.  Sciatica (pronounced sigh‐at‐ih‐kah) is not a medical diagnosis in and of itself ‐ it is a symptom of an underlying medical condition.

SCIATICA NERVE PAIN

Sciatica is often characterized by one or more of the following symptoms:

• Constant pain in only one side of the buttock or leg (rarely can occur in both legs)

• Pain that is worse when sitting

• Burning or tingling down the leg (vs. a dull ache)

• Weakness, numbness or difficulty moving the leg or foot

• A sharp pain that may make it difficult to stand up or to walk

Sciatica Nerve Inflammation Pattern

Sciatic pain can vary from infrequent and irritating to constant and incapacitating. Specific sciatica symptoms also vary widely in type, location and severity, depending upon the condition causing the sciatica.

While symptoms can be very painful, it is rare that permanent sciatic nerve damage (tissue damage) will result.

THE SCIATIC NERVE AND SCIATICA

The sciatic nerve is the largest single nerve in the body and is composed of individual nerve roots that start by branching out from the spine in the lower back and combine to form the "sciatic nerve." When it is irritated, sciatica symptoms occur.

• The sciatic nerve starts in the lower back at lumbar segment 3 (L3).

• At each level of the lower spine a nerve root exits from the inside of the spine and then comes together to make up the large sciatic nerve.

• The sciatic nerve runs from the lower back, down the back of each leg

• Portions of the sciatic nerve then branch out in each leg to innervate certain parts of the leg [e.g. the buttock, thigh, calf, foot, toes]

The sciatica symptoms (e.g., leg pain, numbness, tingling, weakness, possibly symptoms that radiate into the foot) are different depending on where the nerve is pinched. For example, a lumbar segment 5 (L5) nerve impingement can cause weakness in extension of the big toe and potentially in the ankle.

THE COURSE OF SCIATICA PAIN

The incidence of sciatica increases in middle age. Rarely occurring before age 20, the probability of experiencing sciatic pain peaks in the 50's and then declines.

Often, a particular event or injury does not cause sciatica, but rather it tends to develop over time. The vast majority of people who experience sciatica get better within a few weeks or months and find painrelief with non-surgical sciatica treatment. For others, however, sciatica pain from a pinched nerve can be severe and debilitating.

There are a few symptoms that may require immediate medical, and possibly surgical, intervention, such as progressive neurological symptoms (e.g. leg weakness) and/or bowel or bladder dysfunction (Cauda Equina Syndrome).

Because sciatica is caused by an underlying medical condition, treatment is focused on relieving the underlying causes of symptoms. Treatment is usually self-care and/or non-surgical, but for severe or intractable cases surgery may be an option.

MOST COMMON CAUSES OF SCIATICA

• Lumbar herniated disc (also referred to as a slipped, ruptured, bulging, or protruding disc, or a pinched nerve) occurs when the soft inner core of the disc leaks out through the outer core and irritates the nerve root. Sciatica is the most common symptom of a lumbar herniated disc.

• Degenerative disc disease is diagnosed when a weakened disc results in excessive micro-motion at that spinal level, and inflammatory proteins from inside the disc become exposed and irritate the area (including the nerve roots).

• Isthmic spondylolisthesis. This condition occurs when a small stress fracture allows one vertebral body to slip forward on another (e.g. the L5 vertebra slips over the S1 vertebra). The combination of disc space collapse, the fracture, and the vertebral body slipping forward, can cause the nerve to get pinched and cause sciatica.

• Lumbar spinal stenosis is related to natural aging in the spine and is relatively common in adults over age 60. The condition typically results from a combination of one or more of the following: enlarged facet joints, overgrowth of soft tissue, and a bulging disc placing pressure on the nerve roots, causing sciatica pain.

• Piriformis syndrome. The sciatic nerve can get irritated as it runs under the piriformis muscle in the buttock. If the piriformis muscle irritates or pinches a nerve root that comprises the sciatic nerve, it can cause sciatica- type pain.

• Sacroiliac joint dysfunction. Irritation of the sacroiliac joint - located at the bottom of the spine - can also irritate the L5 nerve, which lies on top of the sacroiliac joint, causing sciatica- type pain.

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HOW A DISC BECOMES PAINFUL

This post was taken from our 18 July 14 Spine-Health Powered Newsletter

Each spinal disc is a unique and well-designed structure in the spine. It is strong enough to resist terrific forces in multiple different planes of motion, yet it is still highly mobile and permits motion in multiple directions.

The disc has several functions, including acting as a shock absorber between the bony vertebral bodies.

DISC ANATOMY AND FUNCTION

The intervertebral disc has been likened to a jelly donut. It is comprised of a series of bands that form a tough outer layer, and soft, jelly-like material contained within.

    - Annulus Fibrosus - the disc's firm, tough outer layer

Nerves to the disc space only penetrate into the very outer portion of the annulus fibrosus. Even though there is little innervation to the disc, it can become a significant source of back pain if a tear in the annulus reaches the outer portion and the nerves become sensitized.

With continued degeneration, the nerves on the periphery of the disc will actually grow further into the disc space and become a source of pain.

    - Nucleus Pulposus - the jelly-like inner disc material

The inner material contained in the disc, the nucleus pulposus, contains a great deal of inflammatory proteins. If this inner disc material leaks out of the disc and comes in contact with a nerve root, it will inflame the nerve root and create pain down the leg (sciatica or lumbar radiculopathy) or down the arm (cervical radiculopathy).

When we are born, the disc is comprised of about 80% water, which gives it its spongy quality and allows it to function as a shock absorber. As we age, the water content decreases and the disc becomes less capable of acting as a shock absorber

In the same manner, if any of the inflammatory proteins within the disc space leak out to the outer annulus and touch the pain fibers in this area, it can create a lot of low back pain or neck pain. (See Figure 1)

The proteins within the disc space also change composition, and most of us will develop tears into the annulus fibrosus (the outer hard core of the disc).

Most people will have some level of disc degeneration by their sixth decade, yet most do not have back pain (see Figure 2).

Degenerated Disc on MRI Scan

Magnetic Resonance Imaging, called an MRI scan, has contributed a great deal to our understanding of degenerative disc disease and the natural degenerative process. With the advent of MRI technology, good anatomic detail of the disc can be imaged and correlated with the individual's pain.

Through studies with MRI scans, it was found that:

• A large number of young patients with chronic low back pain had evidence of disc degeneration on their MRI scans, and;
• Up to 30% of young healthy adults with no back pain had disc degeneration on their MRI scans.

Variability in Degenerative Disc Disease

It is not exactly clear why some degenerated discs are painful and some are not.

There is probably a variety of reasons that discs can become painful.

Some theories about pain from degenerative disc disease are:

• If a disc is injured or degenerated, it may become painful because of the resultant instability from the disc injury, which in turn can lead to an inflammatory reaction and causes low back pain.
• Some people seem to have nerve endings that penetrate more deeply into the outer annulus than others, and this is thought to make the degenerated disc more susceptible to becoming a source of pain.

 While the exact causes are not known, there is a generally agreed upon theory of how a disc degenerates over time,....... Click here to read the full article: http://www.spine-health.com/conditions/degenerative-disc-disease/how-disc-becomes-painful