Herniated Disc

Herniated Disc: Definition

A herniated disc is a pathological condition in which a tear in the outer, fibrous ring (annulus fibrosus) of an intervertebral disc allows the soft, central portion (nucleus pulposus) to be extruded (herniated) to the outside of the disc. A herniated disc normally develops from a previously existing disc protrusion (sometimes called a contained herniated disc), a condition in which the outermost layers of the annulus fibrosis are still intact and the nucleus pulposus has not ruptured into the surrounding area. The nucleus pulposus is quite irritating to tissue outside of the disc and creates pain when it comes into contact with nerves. However, a true herniated disc can be called a prolapsed disc, when the annulus is ruptured and the nucleus pulposus has escaped.

Michael Modic, MD, first wrote about variations in signal strength in the MRI imaging of the marrow of vertebral bodies, while he was a professor of radiology and neurology at Case Western. Hence, we have the name Modic changes today to describe this phenomenon.

When Modic changes appear in the vertebral bodies near the endplates of the disc (despite their name, vertebral endplates are part of the disc, not the vertebral body), it confirms the diagnosis of degenerative disc disease (DDD).

(Often bone spurs are also seen in the Ring Apophysis adjacent to these endplates in cases of DDD.)

There are three types of Modic changes and to properly classify them, one must see the T1 and T2 MRIs. These classifications have been confirmed by histological investigations and represent different types of changes to the vertebral body.

Spinal Stenosis

Spinal Stenosis: Definition

Spinal stenosis is the narrowing of the nerve cavaties, which results in pressure on the spinal cord, the cauda equina or nerve roots. The nerve cavaties involved are the spinal canal and the invertebral foramen. The pain for patients with spinal stenosis is severe.

A spondylolisthesis is a type of spinal column instability whereby adjacent spinal vertebrae show a severe break with one another. If the upper vertebra is displaced towards the body than this is a ventrolisthesis, in the opposite direction it is a retrolisthesis. This condition is more severe than luxation or dislocation.

Sometimes, at first, the spondylistheses will hardly show any affects, but the spondylistheses can lead to long-term single or multiple nerve compression or stretching of the nerves in the spinal canal canal. This can cause nerve damage and can lead eventually to the function loss of a nerve.

Spondylolisthesis can lead to paralyses of both legs and the function of bladder and rectum. Simultaneously the spinal discs in the adjacent segments wear down excessively, what can cause additional strong pain.