Do asymptomatic disc herniation exist?

The last few podcasts are all about time dating injuries with imaging.  Is there a way to look at imaging and determine if we have a new injury that was caused by recent trauma or are we looking at pre-existing injuries.  We have gone over multiple ways to help paint a picture of new vs. old.  When we look at all the evidence it becomes easier to determine age of an injury seen on imaging. 

There have been articles published showing a certain percentage of the population have asymptomatic disc herniations.  If this is true there are a lot of people with no symptoms out there that have MRI evidence of disc herniations.  This would make causation and time dating an injury very difficult. 

Today’s study was published in the Journal of Whiplash & Related Disorders 2006 by Anthony D’Antoni and Arthur Croft.  They searched through all studies that showed, asymptomatic disc herniations seen on MRI.  They came up with 5 studies that they were able to review.  I want to go over the findings they have for each of these studies.

The first one is the Teresi et al study.  This study included 100 patients that went in for a larynx MRI.  These MRIs were also assessed for disc herniations.  They saw 20% of people aged 45-54 had disc herniations.  35% of people aged 55-64 had disc herniations and 57% of people older than 64 had disc herniations.  This study did show that for people over 45 we do see findings on MRI. 

This study by Teresi et al has some flaws brought up by the study I am going over today.  The Teresi study did not distinguish between herniated discs and disc bulges.  Remember herniated disc are when the disc material extends beyond it’s normal location in a focal area and bulges are circumferential extensions.  Focal herniations are new injuries and disc bulges are degenerative old injuries.  The Teresi study did not go over the patient’s history or do a physical examination.  They did not verify that these patient’s were asymptomatic.  There was an assumption that since the MRI was not for neck pain that they were all asymptomatic.  The Teresi study likely included in their numbers patients that were symptomatic and likely included patient’s with old degenerative injuries and not new herniations.  The Teresi study has some serious flaws and as the authors of today’s study reported it should be interpreted with caution. 

The second study they reviewed was Boden et al.  They showed that 10% of patients less than 40 years-of-age and 5% of subjects older than 40 had asymptotic disc herniations.  This study did distinguish disc herniations vs. disc bulges and threw out disc bulge findings.  There were no physical exams performed, but they did do a personal interview to ensure that they had no history of cervical symptoms.        

The third study they reviewed was Lehto et al.  This study took 89 asymptomatic patients and divided them into 4 different age groups.  The first group was 10.5 years olds who showed no asymptomatic disc herniations.  The second age group was 22 year olds and this group also did not show any asymptomatic disc herniations.   The third age group was people 29.9 years old and they showed 5% of them had asymptomatic disc herniations.  The fourth age group was 51.9 years old and showed 3.6% of them had asymptomatic disc herniations.  The lehto study did distinguish between disc herniations and disc bulges. 

The fourth study they reviewed was Matsumoto el al study.  This study looked at 497 asymptomatic people with no previous history of cervical spine disease.  This study showed that between the age of 10 and over 60 there is a 2.8% prevalence of asymptotic disc herniations.   This study did distinguish between herniations and bulges. 

The fifth study they reviewed was Siivola et al study.  This study followed asymptomatic patients over a 7-year period and found no discs herniations in this group.  They also followed symptomatic patients over a 7-year period and found 25% of them had disc herniations.  This study only followed 15 people and is not a good number.  They did distinguish between herniations and bulges. 

These 5 studies’ show a large variation in prevalence of asymptomatic disc herniations.  If we throw out the Teresi study then the percentage of disc herniations in asymptomatic patients is from 0-10%.   The Teresi study had very large flaws including no history or exam and no distinguishing between herniation and bulge.  The Boden study showed up to 10% of asymptomatic patients had disc herniations, but this study also did not do any physical examinations on the patients to see if they were asymptomatic. 

If we throw out those 2 studies then 3 of the 5 studies show 0-2.8% of asymptomatic patients have disc herniations seen on MRI.  This shows that it is unlikely that a patient who has a disc herniation showing up on MRI had this prior to their injury and was just asymptomatic.  This is one more piece of evidence that subjective symptoms are important components to new disc herniations and are more likely than not from a new injury.  

Bottom line with MRI and disc herniation is that we need all of the components that we have been talking about to help determine causation.  Today’s study was just one more part of the overall picture.  I think the argument stating that herniations are commonly seen in the general public and have no symptoms is garbage.  Today’s study showed that at best there may be 2.8% of the population that fits into this category.  I personally don’t care about general population, but I care about my patient.  Lets look at the MRI, does it show focal herniation, do we seen modic changes, degenerative bone changes, radicular pain, disc space height loss.  All of these are ways to help determine if this specific patient has a new causally related injury or a pre-existing injury.  It always needs to be about the specific patient and not general population. 

Real world example

I have heard a lot of insurance companies use what I call universal comments.  They often make comments that an MRI showing disc herniation is not from the MVC since lots of people have them with no symptoms.  Or they say there was minimal damage to the vehicle and the patient couldn’t have been hurt in the collision.

These tactics are not helpful.  Don’t tell me since a study showed that people have asymptomatic disc herniations that my patient’s injuries are not from the MVC.  Although as seen in today’s podcast, studies show that asymptomatic disc herniations are very rare.  I do not want to know what may or may not have happened to my patient based on a research article.  I want to take my patient and see what if anything happened to them specifically.  Did they have a traumatic injury with onset of pain?  Did the physical examination warrant an MRI?  Did the MRI show focal disc herniation or was it a degenerative disc bulge?  Is there bony degenerative remodeling around the disc damage indicating an old injury?  Is there loss of disc space height indicating an older injury?   Are there new radicular symptoms that are seen with new injuries and inflammation?  Do we have modic changes surrounding the disc herniation? 

All of this information can help determine what actually happened to a patient.     Todays study was one more piece of evidence showing that new herniations are symptomatic and that subjective evidence is important for helping time date injuries. 

I have found that the important piece of an IME or a final report is to have objective pictures labeled and explained.  I always take the time to show the objective injury and make marks showing the new pathology and an explanation of why the injury is new or why it is old.    

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