Spine Discs 101
Understanding Your Client’s Spine Injury
By Andrew Cash, M.D.
All clients can be better served when their case is better understood…but with personal injury issues, it is not always easy to wrap the mind around medical jargon or procedure descriptions. What follows is an introduction to spinal disc anatomy and pathology, with some generalizations for basic understanding.
Areas Of The Spine
Each spinal disc is located between two vertebral bones. The name of a disc is determined by its region in the spine (cervical, thoracic, lumbar, and sacral) and its location between two specifically numbered vertebral bones. For example, the disc in the cervical spine between the 5th and 6th cervical vertebrae is named the “C5-6 intervertebral disc,” and the lumbar disc between the 4th and 5th vertebrae is considered “L4-5 intervertebral disc.”
Medical Professional’s Tip: When describing a spinal location, often, the term intervertebral (“between the vertebrae”) is omitted (i.e., the L4-5 disc).
Each intervertebral disc comprises two substances: the inner nucleus has a jelly-like material, and the surrounding outer annular fibers form a ring-like structure that surrounds the jelly-like nucleus and keeps it inside the disc space. When the “jelly” pushes the “ring” outwards, the deformity of the disc is described as a bulge, protrusion, herniation, or extrusion. The spinal cord and spine nerve roots occupy distinct spaces behind the discs. These areas are termed “posterior central” (canal), “posterolateral” (lateral recess) and “far posterolateral” (neuroforaminal). Discs that encroach these areas might cause symptoms.
Medical Professional’s Tip: The word “posterior” refers to something being “behind” something else.
Types of Common Injuries
A “disc bulge” is characteristically wider and more circumferential than a disc protrusion. A disc protrusion (synonymous with herniation) is usually localized to a specific portion of the disc (e.g., posterolateral). A “disc extrusion” occurs when disc material has separated from the disc by escaping through the last fiber of the annulus and is located in the spinal canal with the potential to migrate within the canal (i.e., it is a loose disc fragment). There is a great bit of confusion about the definitions of these terms as a universally accepted classification system has not been completely integrated by all healthcare providers.
Medical Professional’s Tip: Within the Las Vegas community, some medical providers might refer to a disc abnormality as a bulge whereas another medical provider might refer to it as a protrusion.
Patient Tips for a Better Spinal Evaluation
When doctors see symptomatic patients, they must determine if one (or more) of the disc abnormalities is responsible for the symptoms. There are usually multiple disc abnormalities on an MRI, some of which are asymptomatic findings and some of which are symptomatic conditions. It is important that a medical provider is able to formulate opinions based on their interpretation of the MRI, the patient’s historical information and the physical findings to determine which radiographic abnormalities are responsible for the patient’s condition.
Patients seeking treatment should consider being prepared to address these issues with their medical provider:
- Any disc abnormality can cause symptoms. Rather than focusing on whether it was called a bulge or a protrusion, ask your medical provider to determine if the disc problem is consistent with the clinical presentation.
- There are often asymptomatic imaging findings and symptomatic conditions on the same radiographic study. Ask your medical provider to distinguish them.