Introduction:

Intervertebral disc herniations are common in today’s population and can be a source of debilitating back and neck pain, but also pain that radiates away from the spine into the shoulders, arms, hands, buttocks, legs, and feet.  Depending on the severity of the herniation and the concomitant symptoms, several approaches have had positive results with respect to treatment.

Anatomy:

The intervertebral disc is a structure located between the bones throughout the spinal column that serve many functions such as shock absortption, aids to movement, and act load bearing structures especially when sitting.  The exterior of the disc, known as the annulus, is made up of dense collagen fibers that are oriented concentrically at various angles to one another, similar to that of a wicker basket.  This orientation helps to increase resistance against shearing forces acting on the disc.  The annulus anchors itself directly into the top of the vertebra (spinal bone) below the disc and into the bottom of the vertebra above the disc.  The interior of the disc, known as the nucleus pulposus, is made up of a hydrated gel-like matter that acts to resist compression.  It is this portion that gives the disc its shock absorbing property.

When the layers that make up the annulus become stretched, or in some cases suffer tearing, the internal gel-like matter that makes up the nucleus is able to leak out into the space surrounding the spinal cord (epidural space).  When this happens, the body reacts the same way it would if a foreign bacteria or virus were to enter it, creating a huge mobilization of inflammatory agents to eliminate the foreign particle.  When this inflammatory storm is created around the nuclear material, everything that surrounds the damaged intervertebral disc becomes irritated.  Structures that are located within close proximity to our intervertebral discs are the spinal nerve roots that exit off of the spinal cord.  These nerve roots give sensation and help control voluntary muscle activity to the muscles located away from the midline of our body such as the muscles in our arms and legs.  When a spinal nerve root becomes irritated, it can produce sensations such as pain, tingling (pins and needles), numbness, increased or decreased sensitivity, and muscle weakness in areas throughout our extremities.  The pain that can be felt is known as radicular pain and the pins and needles sensation is known as paresthesia.

Discussion:

Disc herniations occur frequently in both the cervical spine (neck) and lumbar spine (back).  They can come as a result of severe and sudden trauma such as a motor vehicle accident, a major fall, or attempting to lift an extremely heavy object.  However, most disc herniations are the result of small repetitive trauma or insult against the disc.  Poor posture, daily wear and tear, incorrect lifting position, lack of regular exercise, increases in body weight, and many other environmental, occupational, and lifestyle choices can also have a very negative effect of the health of the intervertebral disc.

Despite the rampant evidence of intervertebral disc herniations seen on both cervical and lumbar MRI (magnetic resonance imaging), it is worth noting that just because there is diagnostic evidence of disc derangement on film, it is difficult to draw any correlation to the findings on MRI and the symptoms being experienced.  In fact, recent studies show as high as 80% of all lumbar intervertebral disc herniations are completely asymptomatic (do not generate pain).  Given the high prevalence of these findings, the discovery on MRI of disc herniations in people with low back pain may frequently be coincidental.