The Neurophysiology of Spinal Manipulation vs. Chiropractic Spinal Adjustments

Spinal Adjustments Realize 64.2% Better Outcomes than Spinal Manipulation

By: Mark Studin DC, FPSC, FASBE(C), DAAPM

Citation: Studin M. Spinal Manipulation vs. Spinal Adjustments. Dynamic Chiropractic, January 2024;42(1).

Back in 1962, Leonard Faye DC, after hearing a presentation on spinal biomechanics, spent a week in a 5-story library in London known for anatomy and created the 5 components of the vertebral subluxation complex. Over the years, many have taken his hypothesis, touted splinters, and tried to use all or some parts as a platform to define the profession. Thankfully, others have used those same hypotheses in the research laboratory and through science, is helping to shape our future. Dr. Faye has been a “lightning rod” to many in the chiropractic profession, but in a conversation with him this past week he is steadfast in his commitment to finding the cause of pain and systemic issues in the human condition. This is the basis for this paper, and as a profession, we all owe Dr. Faye a debt of sincere gratitude.

When we consider clinically, to use either the nomenclature of spinal manipulation or chiropractic adjustment we must consider two of the above components of the vertebral subluxation complex. I have previously written and detailed why we should consider evolving to using the term “Biomechanical Pathology vs. Vertebral Subluxation” as a portal for entry into the healthcare community and remove the nomenclature disconnect so that we can communicate with other professions and increase utilization through collaborative care and referrals. However, based on the evidence in the literature labeling what the chiropractic profession does as manipulation is convenient for carriers to “lump us” with physical therapists and osteopaths. When you look at the science of human physiology, a chiropractic spinal adjustment is not the same as a spinal manipulation, and other than by “happenstance” what we do clinically as chiropractors is far different than osteopaths or physical therapists and renders significantly better outcomes by most metrics as many will be evidenced herein.

The answer to the question is central segmental motor control altering neuromuscular function. Historically, DD Palmer and BJ Palmer discussed “neural tone,” as the cause of pain and dis-ease. Although they slightly missed the mark and were talking about nerve root issues, the evidence, and science has taught us that a bone does not sit on the nerve at the root level. There is, however, strong evidence that the bone sits on the nerve at the facet level^[1], which affects the nociceptors and causes the abnormal joint capsule firing, which is made up of mechanoreceptors^[2], specifically, Pacinian Corpuscles, Ruffini Corpuscles, Golgi Tendon Organs with additional nociceptors. These feed into the dorsal root ganglia and up to the brain, which is part of the foundation of how a high-velocity, low-amplitude thrust (chiropractic spinal adjustment) affecting central segmental motor control.

NOTE: Although DD Palmer and BJ Palmer were not 100% correct, based on the technology available at the time, one has to appreciate the brilliance of their hypothesis and the commitment they made to research to learn more in their purpose to find answers.

The arbiter and ultimate test between the chiropractic spinal adjustment and spinal manipulation is the central segmental motor control (CSMC) changes that occur as sequela to that treatment. The CSMC changes have been evidenced (a topic for another discussion) and are easily defined as central nervous system changes that affect the motor and other functions of the brain afferently. The core of the difference is where the thrust is directed. Haavik et al. (2021) reported, “It is possible to direct a thrust at any spinal segment, regardless of whether it is dysfunctional or not. Therefore, for the purposes of this review, if a thrust is directed at a spinal segment that has not been examined and identified as having clinical indicators of dysfunction, it will be referred to as spinal manipulation. In contrast, a thrust directed at a dysfunctional vertebral motion segment will be referred to as a spinal adjustment. This distinction is important, as adjustments are likely to have different physiological consequences compared to thrusting at or manipulating a vertebral segment that has no signs of motor control dysfunction.”^[3]

The key is determining the dysfunctional segments that make neuroplastic changes are based on outcomes. It is those dysfunctional segments where the high-velocity, low-amplitude thrust or chiropractic spinal adjustment (CSA/HVLA) must be directed, or you will simply be manipulating and not realizing the best outcomes. In determining outcomes, a CSA/HVLA thrust in deep abdominal muscular activation was 38.4% better versus manipulation. Six months later, 19% of that additional muscular activation was retained. A CSA/HVLA thrust increased the H-Reflex and V-Wave (neurological feed to the central nervous system) by 16% without muscular fatigue. That control and manipulation group had no changes in amplitude, and the muscle fatigued much earlier. Maximum voluntary contractions of the jaw increased by 55% to 60% with CSA/HVLA thrusts only after one adjustment. Maximum voluntary contractions increased by 64.2% with chronic stroke survivors, with/HVLA only after one adjustment. A CSA/HVLA spinal adjustment increases motor evoked potentials by 54.5% in the upper limb and 44.6% in the lower limb muscles. A CSA/HVLA Had a 16.76% change in the neurophysiological change in the 30N SEP (brain impulses). It changed brain functioning.^{[4],[5],[6],[7]}

The above evidence explains why chiropractic consistently has better outcomes when treating mechanical spine pain. Chiropractic also has significantly better outcomes when looking at full and partial disabilities because a chiropractic adjustment has a far-reaching effect in changing the central segmental motor control. A chiropractic spinal adjustment also affects the deep paraspinal muscles, which are integral to the proprioceptive system and help make significant neuroplastic changes afferently, resulting in positive efferent changes.^[8],[9],[10] These are topics for a different conversation. Also, determining dysfunctional segments is critical to ensure a chiropractic spinal adjustment is being rendered and not manipulation to realize superior outcomes. This, too, is a topic for a different conversation.

Although language is important, outcomes are more so. A CSA/HVLA thrust realizes those better outcomes and is the core of what chiropractors do. Physical therapists, osteopaths, and other manual therapists do not do what the chiropractic profession does. When it comes to language, subluxation versus biomechanical pathology creates a disconnect, as it discussed theory; however, a chiropractic adjustment versus manipulation outlines very specific results based on the evidence in the literature, which is the basis for superior outcomes.

^[1] Evans, David W. "Mechanisms and effects of spinal high-velocity, low-amplitude thrust manipulation: previous theories." Journal of manipulative and physiological therapeutics 25.4 (2002): 251-262.

^[2] Farrell, S. F., et al. "Cervical spine meniscoids: an update on their morphological characteristics and potential clinical significance." European Spine Journal 26.4 (2017): 939-947

^[3] Haavik, Heidi, et al. "The contemporary model of vertebral column joint dysfunction and impact of high-velocity, low-amplitude controlled vertebral thrusts on neuromuscular function." European Journal of Applied Physiology 121.10 (2021): 2675-2720.
Integration  

^[4] Haavik-Taylor H, Murphy B (2007b) Transient modulation of intracortical inhibition following spinal manipulation. Chiropractic J Australia 37:106

^[5] Haavik H, Niazi I, Jochumsen M, Sherwin D, Flavel S, Turker K (2017)Impact of spinal manipulation on cortical drive to upper and lower limb muscles. Brain Sci 7:2

^[6] Marshall P, Murphy B (2006) The effect of sacroiliac joint manipulation on feed-forward activation times of the deep abdominal musculature. J Manipulative Physiol Ther 29:196–202

^[7] Haavik, Heidi, et al. "The contemporary model of vertebral column joint dysfunction and impact of high-velocity, low-amplitude controlled vertebral thrusts on neuromuscular function." European Journal of Applied Physiology 121.10 (2021): 2675-2720.

^[8]Meier ML, Vrana A, Schweinhardt P (2018) Low back pain: the potential contribution of supraspinal motor control and proprioception. The Neuroscientist. 1073858418809074

^[9] Hellstrom F, Roatta S, Thunberg J, Passatore M, Djupsjobacka M (2005) Responses of muscle spindles in feline dorsal neck muscles to electrical stimulation of the cervical sympathetic nerve. Exp Brain Res 165:328–342

^[10] Haavik, Heidi, et al. "The contemporary model of vertebral column joint dysfunction and impact of high-velocity, low-amplitude controlled vertebral thrusts on neuromuscular function." European Journal of Applied Physiology 121.10 (2021): 2675-2720.