Fissure, protrusion and disc herniation

The most frequent abnormalities are: Lumbosacral transitional anomalies Scoliosis Hyperyphosis Hyperlordosis Rectification Spondylolysis Spondylolisthesis Vertebral arthritis Facet arthritis Spinal stenosis Fissure, protrusion and disc herniation Postoperative fibrosis Dislocation of the coccyx Atlantoaxial Dislocation Sprain Whiplash Syndrome

What it is

Disc fissure consists of the tearing of the fibrous ring around the disc. The most usual type is radial fissure, in which the tear is perpendicular to the direction of the fibers.

Disc protrusion consists of the deformity of the fibrous ring by the impact against it of the gelatinous material from the nucleus pulposus. If the ring breaks and part of the nucleus pulposus becomes extruded, disc herniation is diagnosed.

Fissure	Protusion
Disc herniation	Disc herniation (lateral view)
Disc herniation

How it takes place

Fissure, protrusion, or slipped disc occurs when the pressure inside the disc exceeds the strength of the fibrous envelope.

Since the anterior wall of the fibrous envelope is a third thicker than the posterior wall, most fissures, protrusions and slipped discs occur in the latter.

The typical mechanism consists of the following sequence of movements:

1. Forward flexion of the spinal column: More load is placed on the anterior part of the disc. Because of its gelatinous consistency, the pulpy nucleus is pressed against the posterior wall of the fibrous envelope.
2. Lifting heavy weights: This tends to press one vertebra against another, increasing the pressure inside the disc.
3. Stretching the spine with the heavy weight: The increased pressure on the disc caused by bearing the weight "squeezes" the pulpy nucleus back more strongly. If there is enough pressure against the posterior wall of the fibrous envelope, this tears (disc fissure), swells (disc protrusion), or breaks (disc rupture).

A similar effect can be produced by repeated flexion-stretching movements with a lighter load or even with no load. Every such movement generates small impacts on the posterior wall of the fibrous envelope.

These processes occur much more readily when the muscles of the back are weak. If they are sufficiently developed, these muscles protect the disc by various means.

Symptons

When these lesions cause pain, the main mechanism for the onset of pain is by contact of the fibrous ring nerves with some activating substances located at the nucleus pulposus, namely the phospholipase A2 or PLA2. These substances evoke a very intense pain which patients feel near the spine. If the herniation is important enough, a nerve root may be compressed. In this instance, the patient also refers radiating pain on the arm -in cases of cervical herniation- or on the leg -in cases of lumbar herniation-. In this case the patient feels two sites of pain at the same time, but tends to consider them as one, due to two different causes:

• Neck or upper back pain (cervical herniation), or on lower back (lumbar herniation), due to activation of fibrous ring pain nerves and, after minutes or hours, to the produced reflex muscle contraction, and
• Radiating pain on the arm (cervical herniation) or on the leg (lumbar herniation). The nerve that is compressed in lumbar herniation is the sciatic nerve, hence the name "sciatica".

Risk

In the past it was believed that disc herniation caused pain and signified a risk for patients, who were advised by their physicians to undergo surgery or they would become invalids. It is not true at all. The existing recommendations are based on scientific evidence from studies which show that between 30% and 50% of healthy individuals with one or more disc herniations do not have accompanying problems. If the fibrous ring on the herniation site has few nerve fibers, it is possible that the patient is unaware of his/her anomaly since there may be no associated pain.

It is as hazardous to operate on patients who do not require operation as not to operate on patients who do require operation.

When the patient presents the surgical criteria listed further below, surgery is necessary because:

1. There are studies demostrating that in such cases patients progress better when operated on than when not.
2. If there is medullary damage as described further below or progressive or severe loss of strength over more than 6 weeks, there may be after-effects.

On the contrary, patients not presenting these criteria should not be operated on because:

1. There are studies demonstrating that such cases progress better when not operated on than when operated on.

2. Surgery entails unnecessary risk for these patients and the results are generally counter-productive.

Some of the existing recommendations based on scientific evidence establish that risk of infection or hemorrhage during the first intervertebral disc surgery is under 1%, although this risk increases greatly with older patients or when it is not the first disc operation.

The true risk appears when the operation yields no satisfactory outcomes. Some of the existing recommendations based on scientific evidence establish that, among operated patients with disc herniation without evident signs of nerve compression on physical examination or by electromyogram, less than 40% obtain satisfactory results. Available scientific studies show that the main cause for surgical failure comes from operating on patients who should not have been operated on. The stricter the selection of patients referred for surgery, the better the results

Postoperative fibrosis is another surgical risk. It is accepted that the less aggressive the operation, with less bleeding during surgery, the lesser the risk of onset of fibrosis.

Surgery requires a minimum of general health status. Some general diseases (cardiac, pulmonary or metabolic) can impede surgery.

For all these reasons, some of the recommendations based on the available scientific evidence suggest that it is better not to perform Magnetic Resonance Imaging in the absence of clear indications in its favor. Detection of herniated discs that do not cause problems or for which surgery is not indicated could increase the risk of unnecessary surgery.

Diagnosis

Although a herniated disc can be detected by a scan, Magnetic Resonance Imaging is the preferred procedure.

To determine whether the herniated disc is causing the patient's problems, the clinical history and physical examination are essential. Neurophysiological tests are sometimes also helpful.

Treatment

Even when disc herniation is painful, it can normally be resolved without surgery using other types of treatments.

Some of the existing recommendations based on scientific evidence establish that over 80% of cases of herniated disc are resolved without surgery. Some of these recommendations refer only to lumbar herniated discs but one might accept extrapolating conclusions to other levels of the back -cervical or dorsal-.

These recommendations establish that it is only wise to consider surgery when: