Degenerative Disc Bulge vs Traumatic Disc Herniation


How to Tell If Disc Problems Found After a Car Accident Are Traumatic or Degenerative

This is not a neuroradiological treatise on disc pathology from trauma. This is an overview to make a difficult topic more understandable to treating physicians, insurance adjusters and personal injury attorneys.

The Dilemma of Disc Pathology

A dilemma facing doctors and personal injury attorneys is whether or not a disc problem is caused by the motor vehicle collision in question or is degenerative and therefore not related to the accident. This single fact can make a huge difference in the case. Obviously, the defendants (the insurance company) will want a radiologist to say the disc problem is old and degenerative and predated the collision to escape responsibility. The Plaintiff on the other hand will want the disc condition to be ruled traumatic in origin and caused by the accident to increase the value of their claim.

The Arbiter of Truth

This is where the treating doctor must make a purely clinical decision and report to each side the facts of the matter. The treating doctor must be the arbiter of truth. Medical ethics insists that a treating physician look at the medical facts and report them regardless what that means to a case. The rub of the matter is, and defense experts and insurers will not like this, but it is a fact, studies have shown that approximately 70% of disc lesions found after a car accident were in fact traumatic herniations. Therefore, a plaintiff attorneys should not fear an impartial and ethical treating doctor. After all, the odds are in their favor. The defense must take solace in the fact that they will get their way 30% of the time.

Disc Pathology: Bulge vs Herniation

(American Society of NeuroRadiologists definitions are used)lumbar-disc-normal-labeled


Disc Bulge: bulging or extension of 50% or more of the annular disc tissue beyond the normal disc margin boundaries.lumbar disc bulge

A disc bulge or a degenerative disc is a condition in which due to long standing pressure, activities, obesity, aging, etc the fibers in the outer disc layers lose integrity and begin to spread and expand. The disc ends up bulging out in every direction. Imagine a water balloon and you sit on it. The balloon will “bulge” outward all around. This finding is a bulge and is always degenerative in nature. Disc bulges are usually 3  mm or less in depth and are often associated with abnormal bone growth (osteophytes) around he areas of bulging. Disc bulges because of their generalized size are not referred to as left or right. You will usually see terms such as “circumferential bulging” or “circumferential bulging with osteophytic ridging.”

Disc Herniation: localized extension or displacement of less than 50% of  the disc tissue beyond the normal disc marginslumbar-disc-herniation

Disc herniations, as defined, are discreet areas of disc displacement beyond the disc boundaries. Herniations are a result of trauma. Kinetic forces on the body from a traumatic force causes a significant defect within a portion of the disc and it herniates. The herniation will be seen on MRI immediately after the injury, although it may not appear as symptoms for some time. Annular tears or fissures are actually total disruption of the annulus fibers allowing the nucleus material to migrate through the annulus to the outside. Many tears are usually attributed to degenerative bulging. A solitary tear is caused by a single traumatic event. Any report that reads “left, right or central” as a location of a disc lesion is generally a herniation.

So What’s the Problem?

The problem is many fold and has to do with the expertise of the people reading and interpreting the images. A 2009 Study published in Spine, reported a 42.2% misdiagnosis rate among general radiologists reading spine films. Radiologists disagree on terminology and many use lexicon that is outdated. General radiologists who see a few spines a day or even a week may not be up to date on guidelines. Reading radiologists who do not often report on personal injury medical-legal matters may be careless with their words and write ambiguous reports or use erroneous language.

Most doctors rely on the radiology report, but by doing so will be incorrect almost half the time. Few MD’s or DC’s read their own MR scans and even fewer are actually certified to read them. Sitting in many doctor’s files and in narrative reports lawyers rely on to represent their clients are reports that are completely wrong. Reports that say “bulge” and attribute the lesion to aging, but that are in fact traumatically induced herniations. In general, if you read a report that says “bulge” but also gives a direction such as left or right, be wary. This may be a herniation that was incorrectly called a bulge.

What to Do About This Problem?

It is imperative that ALL MR films be read by both the treating doctor who is specifically trained in spine MRI AND a neuroradiologist. With both sets of trained eyes and using the same ASNR definitions and guidelines, the patient’s condition is much more likely to be accurately reported. This is a major defining point between doctors who treat personal injury cases and those that are specifically trained in these matters.


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