Discogenic Pain Introduction

• The intervertebral discs act as shock absorbers between the vertebral bodies in our spine.
• As we grow older, we lose fluid from the outer fibrous annulus of the disc
• When we lose water from these discs, they become brittle and prone to crack, releasing pain-causing chemicals from the centers of the discs.
• The pressure or leakage from the nucleus of these pain-causing chemicals can cause constant irritation and pain, so-called, discogenic pain.
• Many people will say, "My back went out," to describe this type of pain.
• Most episodes of f discogenic pain heal on their own so surgical interventions and non-surgical mini-invasive therapies should be limited to individuals who have persistent, disabling pain for more than three months, those who have failed all conservative therapies, and/or those who have persistent and increasing neurologic deficits, such as increasing weakness of the foot or legs.

How Discs Cause Pain 

Just like other parts of the body, each intervertebral disc has a nerve supply. Discs are comprised of two parts; the annulus fibrosus (outer ring-like structure) and nucleus pulposus (gel-like interior). The nucleus pulposus is void of nerves. However, the outer third of the annulus fibrosus contains nerve fibers. 

One type of discogenic disorder is called an Internal Disc Disruption (IDD). An IDD occurs when the disc tears or cracks (fissure) allowing the nucleus pulposus to meet the annulus fibrosus. When this happens, a chemical called a protecogylcan may be released from the nucleus pulposus. Protecoglycans may irritate the annular nerves causing an inflammatory response and pain. For unknown reasons, some people have annular tears and yet are symptom free!

The intervertebral discs act as shock absorbers between the vertebral bodies in our spine. As we grow older, we lose fluid from the outer fibrous annulus of the disc. Some of us lose this water quicker and earlier in life than others. Discs begin losing blood supply by age 20. When we lose water from these discs, they become brittle and prone to crack, releasing pain-causing chemicals from the centers of the discs. This is called disc degeneration.

Disc degeneration is loss of water and cracking of the disc. Sometimes, the outer layers of the annulus prevent nuclear fragments from moving outside of the disc (Figure 8, left); however, nuclear fragments may tear through the annular fibers, releasing chemicals into the spinal canal around exiting nerve roots (Figure 8, right). The irritation of nerve endings within the annulus can create referred pain to the back or neck, down into the buttock, thigh, or leg, in the groin, or into the shoulders, arms, and hands.

Diagnosing Low Back Discogenic Pain
Degenerative disc changes can best be seen on MRI.

If one or more spinal discs are suspected as the pain source, the doctor may order a provocative discogram or discography. During this sterile procedure, the suspect discs are injected with a contrast dye to make each disc visible under fluoroscopy. Provocative discography helps the doctor to see the shape and size of the intervertebral disc. The injection of the contrast dye alters the pressure within the disc and may 'provoke' or reproduce the patient's pain pattern; thereby helping to isolate a particular disc as a pain generator.

Non-Surgical Treatments
There are many different types of treatment to help relieve low back and leg pain. Often, treatments are combined for better symptom control or relief.

Medication: anti-inflammatory drugs, anti-depressants, opioids.

Physical Therapy: passive therapies such as ultrasound, transcutaneous nerve stimulation (TENS), and massage may be combined with a disciplined program of stretching and strengthening exercise. Core strengthening (strengthening of the abdominal and low back muscles) is often helpful in relieving pain from degenerative disc disease. When the muscles around the disc become stronger, they may shield the disc from loads and may reduce pain.

Spinal Injections: local anesthetics combined with long-acting corticosteroid injections. This medication combination may be injected into the facet joints or around the nerves of the back to help reduce back pain and radicular leg pain.

Bracing: braces (orthoses) help support the back and limit movement that may provoke painful episodes. Rarely is bracing a long-term treatment for back pain. Long-term bracing may lead to weakened back and abdominal muscles which may provoke muscle spasm.

Alternative Therapies: acupuncture, hydrotherapy and magnet therapy.

Lifestyle Modification: dieting to reach a more 'back friendly' body weight, smoking cessation, and physical activity help maintain a healthy spine.

Minimally Invasive Procedures
Many different spine surgical procedures can be performed using minimally invasive techniques. For example, spine surgeons use such techniques to treat herniated discs, correct scoliosis, and perform spinal fusion. The benefits to the patient are enormous and include smaller incisions, shorter time hospitalized, less post-operative pain, and a speedier recovery. Spinal fusions may alleviate disc related back pain by replacing the disc with bone and cages. Recently, artificial lumbar discs have become another option to replace degenerated discs.