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Is Sway A True Measure Of Balance Following Peripheral Nerve Decompression?

It was a hot, steamy night in the Big Easy and I was feeling good. I had just gotten my pass to the hottest new club, the Metrix. It was very swanky. Just to get in the joint, you had to dress in black tie, grease the palms of the bouncers at the entrance with some Benjamins, and pretend that you really did belong. Wow, it was like something out of an F. Scott Fitzgerald novel and as the music played, I became mesmerized.

When marimba rhythms start to play, dance with me, make me sway. Like a lazy ocean that hugs the shore, hold me close, sway me more.”

No it was not Michael Bublè up there on the stage, it was Nate and the Dynamic Arcs. It is funny how a lyric can transport your mind back to a different place and time. It was ethereal to say the least.

It was that catchy lyric “sway me more” that got me reflecting back to that article I had just read on balance testing after peripheral nerve decompression surgery in patients with diabetic peripheral neuropathy. The article was published earlier this year in Clinical Rehabilitation.1 It came out of the University of Utrecht and was written by Macaré van Maurik and colleagues. Say that fast three times after your second or third glass of cabernet. I dare you! Now what she and her coauthors found was that there was no benefit to improvement in balance with patients who had unilateral nerve decompression.

This was interesting from a couple of standpoints. First, it would be hard to believe that van Maurik had any confirmation bias as she has published other articles on the positive benefits of nerve decompression surgery in patients with diabetic peripheral neuropathy.2

As I swirled the vodka-coated rocks around in my empty crystal glass, I kept hearing the words “sway me more” rattle around my cranial acoustic chamber. Something had to be wrong with that study as I had numerous patients relate that their balance had improved after nerve decompression. How could it be? It was about that time that the band stopped playing and Nate the bandleader came over to my table. 

Now I do not know what made the bandleader come over to my table. (I would like to think it was the very cool limited edition Robert Graham shirt I was wearing but it might have been the four scantily clad “Gatsby” girls that I was sitting with. Nah, it had to be my charisma or maybe it is just a writer’s concoction to tell the damn story.)

So I started to talk with Nate the bandleader and I quickly discovered that this was not his day job. No sir! This purveyor of fine music was an entrepreneurial occupational therapist by day and a true expert at it. In fact, he designed this new instrument he calls the “Dynamic Arc” and it is a concert maker in and of itself. 

Here is what he told me: “While we have identified sway as an important component of balance, it comprises only a small portion of actual measurement. When sway is used as the sole outcome measure, it is not appropriate to determine global balance deficits. Tests such as the Balance Evaluation Systems Test (BESTest) incorporates six balance measurements (biomechanical constraints, stability limits/verticality, anticipatory postural adjustments, postural responses, sensory orientation, and stability in gait) and the Physiological Profile Assessment (PPA) measures five components (visual, proprioception, strength, postural sway and reaction time). Both measures are clinically relevant to this population, are evidence-based and accepted as valid and reliable. These two, however, do not tie in objective functional balance measurements as the Dynamic Arc does.”3

Now I was fascinated. I love being surrounded by raw knowledge and intellectualism as I get so little of that when I’m by myself, or with my usual band of buddies. 

I had explained to him that this study happened after just one extremity had decompression. It did not correlate with anything I, or for that matter any of my colleagues, had seen as nearly all my patients comment on how much better their balance is after their surgery.

“Nate, tell me about sway as a true measure of balance, especially after nerve decompression,” I asked. The bandleader shifted in his seat, tapped the table with adroit syncopation and softly whistled melodiously, glancing up toward the chandelier while contemplating on how to respond. 

“Posturography is an appropriate measure of body sway in the neuropathic population. However, it has been accepted that postural sway has poor specificity when examining the underlying pathophysiology. Postural sway is a complex behavior that depends on MANY (caps to emphasize his baritone NFL player-like deep voice with inflection) parts of the central and peripheral nervous system, and musculoskeletal system.”4

He quickly left our table when he saw the rest of his band return to the stage out of the corner of his eye. I thanked him for helping me understand the assessment of balance and why this article flew in the face of what we had seen for the last decade plus.  

The music started to play again and there it was: “Like a flower bending in the breeze, bend with me, sway with ease … .” Nate pointed to our table, flashed a huge smile and bowed in our direction. I knew that the reprise was directed at me and I liked it. No band plays such a great song twice in one night.

The Dynamic Arc™ is manufactured by Functional Innovation and it is a very useful tool you should consider implementing into your practice. No, I have no financial interest in this wonderful instrument. Check it out and sway with me.

References

1.      Macare van Maurik JF, Ter Horst B, van Hal M, Kon M, Peters EJ. Effect of surgical decompression of nerves in the lower extremity in patients with painful diabetic polyneuropathy on stability: a randomized controlled trial. Clinical Rehabil. 2015; 29(10):994-1001.

2.      Macare van Maurik JF, van Hal M, van Eijk RP, Kon M, Peters EJ. Value of surgical decompression of compressed nerves in the lower extremity in patients with painful diabetic neuropathy: a randomized controlled trial. Plast Reconstr Surg. 2014; 134(2):325-332.

3.      Mancini M, Horak FB. The relevance of clinical balance assessment tools to differentiate balance deficits. Eur J Phys Rehabil Med. 2010; 46(2):239-248.

4.      Ledin T, Odkvist LM, Vrethem M, Moller C. Dynamic posturography in assessment of polyneuropathic disease. J Vestib Res. 1990; 1(2):123-128.

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