• How is the spine designed?
• What is the purpose of the spine and its discs?
• What is degenerative disc disease?
• What are radiculopathy and sciatica?
• How is radiculopathy diagnosed?
• How is radiculopathy treated?
• What is bony encroachment?
• Degenerative Disc Disease & Sciatica At A Glance

How is the spine designed?

The vertebrae are the bony building blocks of the spine. Between each of the largest part of the vertebrae are the discs. Ligaments are situated around the spine and discs. The spine has seven vertebrae in the neck (cervical vertebrae), twelve vertebrae in the mid-back (thoracic vertebrae), and five vertebrae in the low back (lumbar vertebrae).

What is the purpose of the spine and its discs?

The bony spine is designed so that vertebrae "stacked" together can provide a movable support structure while also protecting the spinal cord (nervous tissue that extends down the spinal column from the brain) from injury. Each vertebrae has a spinous process, which is a bony prominence behind the spinal cord that shields the cord's nerve tissue. The vertebrae also have a strong bony "body" in front of the spinal cord to provide a platform suitable for weight-bearing.

The discs are pads that serve as "cushions" between each vertebral body which minimize the impact of movement on the spinal column. Each disc is designed like a jelly donut with a central softer component (nucleus pulposus). This softer component can rupture (herniate) through the surrounding outer ring (annulus fibrosus) and irritate adjacent nervous tissue. Ligaments are strong fibrous soft tissues that firmly attach bones to bones. Ligaments attach each of the vertebrae and surround each of the discs. When ligaments are injured as the disc degenerates, pain in the area affected can result.

What is degenerative disc disease?

As we age, the water and protein content of the body's cartilage changes. This change results in weaker, more fragile and thin cartilage. Because both the discs and the joints that stack the vertebrae (facet joints) are partly composed of cartilage, these areas are subject to wear and tear over time (degenerative changes). The gradual deterioration of the disc between the vertebrae is referred to as degenerative disc disease.

Degeneration of the disc is medically referred to as spondylosis. Spondylosis can be noted on x-ray tests or MRI scanning of the spine as a narrowing of the normal "disc space" between the adjacent vertebrae.

Degeneration of the disc tissue makes the disc more susceptible to herniation. Degeneration of the disc can cause local pain in the affected area. Any level of the spine can be affected by disc degeneration. When disc degeneration affects the spine of the neck, it is referred to as cervical disc disease. When the mid-back is affected, the condition is referred to as thoracic disc disease. Disc degeneration that affects the lumbar spine is referred to as lumbago. Lumbago causes pain localized to the low back and is common in older persons. Degenerative arthritis (osteoarthritis) of the facet joints is also a cause of localized lumbar pain that can be detected with plain x-ray testing. The pain from degenerative disc or joint disease of the spine is usually treated conservatively with intermittent heat, rest, rehabilitative exercises, and medications to relieve pain, muscle spasm, and inflammation.

What are radiculopathy and sciatica?

Radiculopathy refers to nerve irritation caused by damage to the disc between the vertebrae. This occurs because of degeneration ("wear and tear") of the outer ring of the disc, or because of traumatic injury, or both. Weakness of the outer ring leads to disc bulging and herniation. As a result, the central softer portion of the disc can rupture through the outer ring of the disc and abut the spinal cord or its nerves as they exit the bony spinal column.

When nerves are irritated in the neck from degenerative disc disease, the condition is referred to as cervical radiculopathy. This can lead to painful burning or tingling sensations in the arms. When nerves are irritated in the low back from degenerative disc disease, the condition is called lumbar radiculopathy and it often causes the commonly recognized "sciatica" pain that shoots down the lower extremity. This condition can be preceded by a localized low back aching. Sciatica pain can follow a "popping" sensation at onset and be accompanied by numbness and tingling. The pain commonly increases with movements at the waist and can increase with coughing or sneezing. In more severe instances, lumbar radiculopathy can be accompanied by incontinence of the bladder and/or bowels.

How is radiculopathy diagnosed?

Radiculopathy is suspected when the symptoms described above are noted. The doctor can sometimes detect signs of irritated nerves during the examination. For example, increased radiating pain when the lower extremity is lifted supports the diagnosis of lumbar radiculopathy. Nerve testing (EMG/electromyogram and NCV/nerve conduction velocity) of the lower extremities can be used to detect the nerve irritation. The actual disc herniation can be detected with radiology testing, such as CAT or MRI scanning. For more information, please read the CAT Scanning and MRI Scanning articles.

How is radiculopathy treated?

The treatment of radiculopathy ranges from nonsurgical (medical) management to surgery. Medical management of radiculopathy includes patient education of the condition, medications to relieve pain and muscles spasm, cortisone injection around the spinal cord (epidural injection), physical therapy (heat, massage, ultrasound, electrical stimulation), and rest (not strict bed rest, but avoiding re-injury). With unrelenting pain, severe impairment of function, or incontinence (which can indicate spinal cord irritation), surgery may be necessary. The operation performed depends on the overall status of the spine, and the age and health of the patient. Procedures include removal of the herniated disc with laminotomy (a small hole in the bone of the spine surrounding the spinal cord), laminectomy (removal of the bony wall), by needle technique through the skin (percutaneous discectomy), disc- dissolving procedures (chemonucleolysis), and others.

What is bony encroachment?

Any condition that results in movement or growth of the bony vertebrae of the spine can limit the space (encroachment) for the adjacent spinal cord and nerves. Causes of bony encroachment of the spinal nerves include foramenal narrowing (narrowing of the portal through which the spinal nerve passes from the spinal column, out of the spinal canal to the body), spondylolisthesis (slipping of one vertebra relative to another), and spinal stenosis (compression of the nerve roots or spinal cord by bony spurs or other soft tissues in the spinal canal). For example, lumbar spinal nerve compression in these conditions can lead to sciatica pain which radiates down the lower extremities. Lumbar spinal stenosis can cause lower extremity pains which worsen with walking and are relieved by resting (mimicking poor circulation). Treatment of these conditions varies (depending on the severity and condition of the patient) from rest to surgical decompression by removing the bone that is compressing the nervous tissue.

Degenerative Disc Disease & Sciatica At A Glance

• The discs of the spine serve as "cushions" between each vertebral segment.
• The discs are designed somewhat like a jelly donut.
• Degeneration (deterioration) of the disc makes the disc more susceptible to herniation (rupture) which can lead to localized or radiating pain.
• Sciatica can result from disc herniation when nerves of sensation in the low back are irritated.