AMA Guides for Impairment ratings and disc herniations. There are no asymptomatic disc herniations.

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Welcome back to the Forensic Chiropractor podcast.

I have not spent that much time talking about impairment rating on my podcast.  They are an important part of a personal injury cases.  This is a way to quantify an injury.  Impairment ratings are give as whole person ratings.  A rating would be a way of saying how much of an injured person’s body was lost in an injury.  A 10% whole person impairment rating is equivalent of saying the patient lost 10% of their body in the injury.  While I do not always agree with the impairment rating texts, it does allow me the opportunity to give a rating based upon published text from multiple providers.  This can go beyond just my opinion and allow a published opinion on how serious an injury is.

The impairment rating guides are a published textbook by the American Medical Association.  The impairment rating guide are on the 6^th edition.  In the stat of Utah we have a state specific set of guides.  The State specific guides for Utah closely follow the 5^th edition.  Some states mandate what version of the guides are used.  In Utah the state mandates using the Utah guides for worker’s compensation injuries.  For other personal injury cases the state of Utah doesn’t mandate the use of any version. 

I have always tried to use the latest version of the impairment rating guides.  We all know things change in healthcare and it can be hard to keep up with the latest updates.  The impairment rating guides have attempted to keep up and be accurate.  The 6^th edition originally came out in 2007.  Instead of publishing a new version they have decided to keep the 6^th edition, but periodically give updates.  The latest update came out in 2024. 

The 2024 version should not be considered an update in my opinion, but a new version.  It has taken me some time to make the switch to the new version, but I feel like it is important to keep up with the new versions.  There are a lot of changes and for the most part they make sense to me.  I feel like they dramatically decreased the whole person impairment rating for alteration of motion segment integrity or AOMSI.  I feel like AOMSI is a more significant injury than they are rating it.

The biggest problem I have with the new version is the disc herniation section.  I want to read from section 17.03a2g about disc herniations they saquote “The vast majority of disc herniations in adults cannot be related to a specific traumatic episode.  Disc herniations are a common finding on imaging and occur in asymptomatic individuals.  They are most often the result of degenerative changes” end quote.

Following this paragraph they cited 2 research articles for reference.  I want to spend some time today going over these research articles.  The guides report that we can no longer give an impairment rating for disc herniations without neurologic findings.  Often, we will have new disc herniations with neurological findings, but on occasion we will have disc herniations with no neurological findings, but lots of pain. 

The first study they cited that I want to cover is Systematic Literature Review of Imaging Features of Spinal Degeneration in Asymptomatic Populations by Brinjikji (BRINJICK) et al published in the spine journal in 2014. 

This study was to designed to quote “estimate the prevalence of common degenerative spine conditions” end quote.  This study was not done to assess prevalence of new acute disc damage in asymptomatic populations.  Neither was this study done to assess disc damage frequency in injured patients. 

They reported that Quote “Our study does not imply or conclude that the above-mentioned degenerative findings are always age-related rather than pathologic.  Our study applies more to cases in which such degenerative findings are incidentally seen in the evaluation of patients without low back pain or findings are found at a level that does not correlate with findings on physical examination” end quote. 

This study was a literature review of 33 articles of asymptomatic patients with degenerative changes seen on imaging.  They searched for and included studies of degenerative changes and not new disc herniations.  They looked for studies with degenerative changes including degenerative discs, disc signal loss or desiccation, disc height loss, disc bulge, annular fissures, facet degeneration, spondylolisthesis and disc protrusion. 

Besides disc protrusion all of their inclusion criteria are seen with old degenerative disc problems.  The criteria they used I covered in my podcasts about age dating an injury.  These changes would not be seen in a new disc herniation, but older degenerative disc bulges. 

The term disc protrusion is a descriptive word used for a type of herniation.  The problem is that this study went back to 1946.  The terms used to describe disc pathology have been interchanged a lot over the years.    The term protrusion was often used for any disc material sticking out beyond the vertebra.  This could be a bulge or a herniation. 

The nomenclature for disc damage was only established in 2001 and then updated in 2014.  There are a lot of articles that would have used a protrusion as a bugle and not a description of a herniation.  That is likely the reason that they did not use extrusion as an inclusion criteria for their study.  An extrusion is also a descriptor for a disc herniation.  They were aware of this nomenclature issue and reported this as a limitation for their study.    

It is clear that a reading of this study shows that they are not looking for or saying that the general population will have disc herniations with no symptoms.   They are clearly saying that a percentage of the population have degenerative disc changes without symptoms.  Rember a disc bulge is a circumferential extension of disc material beyond the vertebra.  A herniation is a focal extension of disc material beyond the vertebra. 

If you listened to the 8^th podcast you will have heard a rebuttal of prior studies reporting asymptomatic disc herniations. If you listened to my 10^th podcast you would have heard how a new disc herniation can be very painful.  It is clear that degenerative old disc injuries can be asymptomatic in the population, but new disc herniations from trauma are likely painful. 

The 10^th podcast describes how disc herniations are not just painful, but lead to permanent changes that have the potential to cause problems for the rest of the patient’s life.  These permanent changes are specific to the disc and not neurological damage.  For these reasons I disagree with the new version of the impairment rating text taking disc herniations without neurological findings out of the guides. 

I assume the intention was to take degenerative disc bulges out of the guides.  I am not sure if they did not understand the difference or how to tell a new disc injury to an older degenerative one.  I am sure there have been impairment ratings given in the past for old degenerative disc bulges.  I agree that this should be stopped, but I disagree with new disc herniations being taken out of the guides. 

For your information this study did show that 37% of people age 20 and 96% of people age 80 have asymptomatic degenerative disc changes.  It is clear that a large percentage of our population will have disc damage throughout their lives.  The point of this study was to not blame incidental degenerative changes as the cause for pain.    This study did not show that disc herniations are a common finding in the asymptomatic population as reported in the AMA Guides.  This study did show that degenerative disc changes are common in the asymptomatic population. 

The second study cited in the impairment guides is Inciting Events Associated with Lumbar Disk Herniation by Suri et al published in the Spine Journal in 2010.  Unlike the last study which looked at degenerative disc this study looked at lumbar disc herniation.  There is no discussion about the way they defined disc herniation vs. disc bulge.  The inclusion criteria were radicular pain within 12 weeks and an MRI showing a disc herniation corresponding with the radiculopathy level. There was no discussion about the type of disc and how disc herniation was defined.  It is impossible to know if degenerative disc bulges were included. 

They took 154 consecutive patients that fit their criteria.  They divided these 154 patients into 6 categories.  These 6 categories are reported causes of injury.  The first was heavy lifting.  The second light lifting.  The 3^rd was physical activities like sports.  The 4^th was trauma.  The 5^th was non-exertional occurrences such as coughing, sneezing and bearing down.  The 6^th was spontaneous or no reported cause. 

They reported that 8% or 12 of these patients had a workers compensation injury.  Only 1.3% or 2 patients had trauma.  This study should have no bearing on disc herniations from trauma given that only 2 people with trauma were included in the study. 

They want to know what percentage of these patients have disc herniations without knowing the cause.  They showed that 62% of participants did not know the cause for their disc herniation with radiculopathy.  Keep in mind that this study population was very limited on trauma patients with less than 1.3% or just 2 patients.  There is no way to say that onset of disc herniation after trauma is not related to the trauma since 62% of patients in this study had disc damage without knowing the cause.  Also, this study in no way says that 62% of patients have asymptomatic disc herniations since all the participants had pain.   This study showed that 100% of their population had symptoms with disc damage.   

Also, it seems likely and can’t be excluded that a lot of this 62% of patients could have had degenerative disc changes consistent with an old injury.  There could have been disc space height loss, disc desiccation, osseous degenerative changes and other signs of an old disc injury.  What we do know is that they may have been unsure of the onset of radiculopathy.  

For me the conclusion of this study should be that 62% of the time the general population will have radiculopathy from disc problems and be unsure of the cause.  Since I am assuming this includes degenerative disc bulges that statistic makes sense to me.  Degenerative disc bulges can by asymptotic and degenerate enough over time to start irritating the nerve root and lead to radiculopathy. 

Since they did not distinguish between new disc damage and degenerative discs it is impossible for me to know how in any way this study shows that disc herniations are seen in the general population without pain or like the guides.  The impairment guides say quote “The vast majority of disc herniations in adults cannot be related to a specific traumatic episode” end quote.  This was based on this second study, but should not have been in my opinion.  Only 2 people in this study had a traumatic event.  Only 12 patients in this study had a work place injury.  They didn’t have enough trauma patient in this study to report that the vast majority of adults with disc herniations cannot be related to a specific traumatic episode.  The patients they studied didn’t even have an episode. 

The 2024 version of the impairment rating guides may have changed, but I do not think that will change a lot for me.  I still have to take every patient and see what happened to them.  If they have an MRI, I need to look for the signs of a new injury or an old injury.  It becomes easy to see a new disc herniation compared to a degenerative disc bulge. 

If I have a patient with all the signs of a new disc herniation, but they never had radicular symptoms then the new impairment rating guides will not allow for an impairment.  This is something I strongly disagree with.  The research articles we covered and were cited in the impairment rating guides do not support that new disc herniations are seen in the general public and are asymptomatic or that they cannot be related to a specific traumatic event.

Real world example

A few years ago I had a new patient that was just in a MVC.  There were no neurological findings on my examination.  I will typically not order an MRI after trauma unless there are neurological findings.  We came up with a treatment plan and treated for the first month.  He made progress besides in the cervical spine.  Given the lack of progress after 1 month I ordered a cervical spine MRI.  The MRI came back with a protrusion type disc herniation.  The MRI did not show nerve root abutment or compression.  This disc herniation did have all the signs of a new herniation.  There was no loss of disc space height, no degenerative osseous changes surrounding the disc.  The herniation was focal.  There was an increased signal in the herniation. 

It was clear that the recent MVC was the cause of the new disc herniation and onset of pain.  He did not have any prior treatments for neck pain and no prior injuries.  This was a classic example of a new herniation related to a MVC.  The pain from the disc did radiate to the upper back.  The pain slowly progressed over 4 months.  After 4 months we took 1 month off of care to see how he would do without active care.  At the end of this month his symptoms returned, but at a lower level.  He came in for another treatment and felt good for the next 3 weeks and then the pain came back on.  Since then, he has been able to go 4-12 weeks without symptoms.  As long as he is coming in to manage his permanent injury his symptoms are being managed. 

This shows how a disc herniation can be a permanent injury.  The disc will lose height after a herniation.  The loss of disc space height will bring the facet joints in closer proximity and this will alter the mechanics of this joint leading to inflammation, degenerative changes and symptoms.  Over time the disc itself will have an increase in nerve growth into the center of the disc where nerves were never meant to grow.  This increased nerve growth will lead to symptoms over time. 

It became clear that this patient was at MMI but this permanent injury will cause him symptoms throughout his life.  When writing his final report, he was able to qualify for a 6% whole person impairment rating according to the AMA Guides to the Evaluation of Permanent Impairment 6^th edition.  With the new version of the impairment rating guides, he would not qualify for an impairment rating. 

This seems wrong to me.  The studies they cited to support taking this impairment rating away do not apply to this patient and these circumstances.  tt first study we covered today would only apply to my patient if the MRI showed degenerative changes.  Then an argument could be made that these degenerative changes are not likely related to the MVC and no impairment rating should be given for these degenerative changes.  I completely agree with keeping degenerative changes out of the guides, but this patient clearly had new findings and no degenerative changes.

The second study doesn’t apply to my patient since only 1.3% or 2 patients in their study had a traumatic event.  Keep in mind that both of these 2 patients with trauma did have pain.  This second study did not define what a disc herniation was.  There is no way to know if they were studying degenerative changes as well.  Not to mention the second study only included patients who had nerve root damage or radiculopathy.  My patient did not have radiculopathy and would not fit their study.  This study’s results would just not apply to him. 

I can’t state it enough that I disagree with the AMA Guides on this topic.  My patient in this example should qualify for an impairment rating.   They cited 2 studies showing that he shouldn’t qualify for an impairment rating, but I have shown how these studies to not apply to him and shouldn’t be used. 

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