Hidden Spondylolisthesis

Over the past decade, we have seen the appearance of CT and MRI studies which are termed “dynamic” or “functional” because they have made the bold leap to taking a shot which is not in the classic neutral posture.  They can be done in the upright position, as with upright MRI, which produces data sets in flexion, extension, or the lateral flexions, or they can be done in the recumbent position, with the cervical spine in rotation.  And these studies are gaining more credibility day by day as they wake up and realize that just because something appears to have normal bony alignment in the neutral, “default” position, that by no means guarantees that the alignment will be normal when the joint is stressed by motion.

The exception to all of the above has been the lumbar motion study, which consists of standing flexion and extension projections.   My opinion has been for some time that performing a proper lumbar motion study is a lost art amongst today’s rad techs, and the radiologists who supervise them, but I have been able to get some very good studies out of Radiology Ltd. because I took the time to go over to the Radiology Ltd. on N. Wilmot, and teach a rad tech exactly how I wanted it done.  Now, when I fill out my prescription form, I just indicate that I want my favorite rad tech to do the study, and I always get a set of films in which maximum stress has been placed on the facet and discal joints, so I can draw the lines and measure for linear and angular displacement, as per the methods described in the AMA Guides to Evaluation to Permanent Impairment, 6th Ed.  I have identified a lot of unstable lumbar spines that way, and good thing, too, because my DMX machine is pretty worthless in obtaining a decent lumbar motion study with adequate resolution and a video centered to my image intensifier.  But about a month ago, I ran across an article which has gotten me to reconsider my attitude on this.

You can’t get much more recent than this.  The article:

Landi A, Gregori F, Marotta N, and Donnarumma P.  Hidden Spondylolisthesis:  Unrecognized Cause of Low Back Pain?  Prospective Study About the Use of Dynamic Projections in Standing and Recumbent Position for the Individuation of Lumbar Instability.  Neuroradiology (2015) 57:583-588

Whoa.  “Hidden Spondylolisthesis.”  What red-blooded, professionally trained chiropractor wouldn’t want to read about that?!

So, because I don’t have a life, I sent an e-mail to my chiropractic alma mater’s librarian and requested the article, and they got it for me in a jiffy.  I don’t know if all of you know that you can do that, and it’s a really good thing to do, because just about all intellectual property nowadays has a price tag on it (like anywhere from $39 to $55 for a copy of an article), which makes chasing down research articles pretty expensive.  But your friendly neighborhood chiropractic college librarian can get you whatever want, free of charge.

The authors are all from the Department of Neurology and Psychiatry, Division of Neurosurgery, “Sapienza” University of Rome.   Between January 2011 and January 2013, they analyzed 200 patients with lumbar degenerative disease, with three diagnostic modalities:  MRI, standing dynamic x-ray (SDXR), and recumbent dynamic x-ray (RDXR).  They drew lines to measure the anterolistheses they found, and they applied the following standards for determining instability:  sagittal translation greater than or equal to 4 mm. (an absolute value) or greater than or equal to 8% (a relative value).  They did not address angular displacement.  The results were very surprising.

  1. 53 patients (26.5%) showed lumbar instability with SDXR, but not with RDXR;
  2. 43 patients (21.5%) showed lumbar instability with RDXR, but not with SDXR;
  3. 90 patients (45%) showed no lumbar instability with either SDXR or RDXR;
  4. 14 patients (7%) showed lumbar instability in both SDXR and RDXR.

Points 1 and 2 reveal that a significant amount of spinal instability is missed with just using standing x-rays to evaluate for instability.  The article is a little hard to understand in parts because the authors are Italian, and their translation into English could probably be a little better (but what the heck, their English is probably a lot better than my Italian), because there aren’t details about how they positioned the patients for the recumbent shots, but I am betting that they had the subjects really tuck and pull their knees to their chests for the flexion shots.  Their hypothesis was pretty simple:  in the standing position, “the paravertebral muscles act as a stabilizer of the hypermovement that generates instability because of their antalgic contraction and augmented muscular tone, and that this phenomenon can reduce sagittal translation and ‘hide’ lumbar instability.”  Lying on their right sides, the reduction of the “antalgic hypertonus” allowed the true degree of the slippage to manifest.

The authors went on to state that the identification of a “hidden” spondylolisthesis can change the therapeutic course of a patient.   In other words, if an MRI determines that a patient needs a decompression surgery, and a standing dynamic flexion x-ray did not reveal a  “hidden” spondylolisthesis,  a decompression-only surgery might not lead to an improvement of the lumbalgia.  They go on to state that “the natural course of this clinical condition should lead to a worsening of the instability with an augmentation of the pain symptoms and a worse clinical condition.”

The application to a personal injury practice is clear.  Suppose you do the standing lumbar motion study, and no instability (at least in translation) is identified.  Should you stop there, and just accept that there is no instability?  Probably not.  If the low back pain is still present, and enough time has been spent on a reasonable program of conservative care, then why not order the recumbent flexion and extension shots?   Unidentified, and improperly treated, spinal instability is probably why the literature tells us that anywhere from 55-88% of car crash victims go on to become chronic pain victims.