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Chiropractic care is commonly thought to have a beneficial effect on the functioning of the human body by affecting the nervous system. Evidence indicates that chiropractic adjustments result in plastic changes in sensorimotor integration within the central nervous system in human participants, particularly within the prefrontal cortex. Adjustments appear to alter the net excitability of the low-threshold motor units, increase cortical drive, and prevent fatigue (see this blog).  This same group of researchers have more recently found an increase cortical drive to upper and lower extremity muscles following manipulation as measured by motor evoked potential. The researchers suggested the effects were due to descending cortical drive and could not be explained by changes at the level of the spinal cord (although they can’t rule that out completely).  Two experiments were conducted.  In experiment one, transcranial magnetic stimulation input–output (TMS I/O) curves for an upper limb muscle (abductor pollicus brevis; APB) were recorded, along with F waves prior to and after either spinal manipulation or a control intervention for the same subjects on two different days. During these two separate days, lower limb TMS I/O curves and movement related cortical potentials (MRCPs) were recorded from tibialis anterior muscle (TA) before and after spinal manipulation. Spinal manipulation resulted in a 54.5% ± 93.1% increase in maximum motor evoked potential (MEPmax) for APB and a 44.6% ± 69.6% increase in MEPmax for TA. 
They conclude that “Spinal manipulation may therefore be indicated for the patients who have lost tonus of their muscle and or are recovering from muscle degrading dysfunctions such as stroke or orthopaedic operations. These results may also be of interest to sports performers. We suggest these findings should be followed up in the relevant populations.”

Reference: Haavik H, Niazi IK, Jochumsen M, Sherwin D, Flavel S, Türker KS. Impact of Spinal Manipulation on Cortical Drive to Upper and Lower Limb Muscles. Brain Sci. 2016 Dec 23;7(1).

 

adobestock_49611047Over the last decade, research has demonstrated that spinal manipulation can change various aspects of nervous system function, including muscle reflexes, cognitive processing, reaction time, and the speed at which the brain processes information. One research group from New Zealand (Haavik et al) has hypothesized that the articular dysfunction part of the chiropractic clinical construct, the vertebral subluxation, results in altered afferent input to the central nervous system (CNS) that modifies the way in which the CNS processes and integrates all subsequent sensory input. This processing (i.e., sensorimotor integration) is a central nervous system (CNS) function that appears most vulnerable to altered inputs.

Investigators utilizing techniques such as transcranial magnetic stimulation and somatosensory evoked electroencephalographic (EEG) potentials have suggested that neuroplastic changes occur in the brain (e.g. primary sensory cortex, primary motor cortex, prefrontal cortex, basal ganglia, and cerebellum).  Inducing and recording somatosensory evoked potentials (SEPs) is emerging in scientific literature relating to spinal manipulation (SM). There is evidence to support that SEPs are able to elucidate differences in cortical activity associated with SM. Studies with only a few recording EEG electrodes allow investigation of evoked potential amplitudes and latencies and have shown changes in the N30 somatosensory evoked potential (SEP) amplitudes following spinal manipulation.  The N30 response from the frontal lobe peak reflects sensory integration.

With recent advances in the spatial resolution of EEG, it is becoming possible to better anatomically localize the signal.  With this study, the authors aimed to utilize brain electrical source analysis to explore which brain sources are responsible for changes in N30 amplitude following a single session of spinal manipulation.

Nineteen young (average age 26 years) subclinical pain volunteers were included in the study. Subclinical pain (SCP) refers to recurrent spinal ache, pain, or stiffness for which the subject had not sought treatment. Subjects were excluded if they had: no evidence of spinal dysfunction, they were in current pain, they had sought previous treatment for their spinal issues, or they had contraindications to receiving spinal manipulation. The EEG signals were recorded with the Neuroscan System from 62 scalp electrodes using the extended 10-20 system montage. Supine subjects received electrical stimulations applied to the median nerve at the right wrist to evoke SEPs. Two trials of 1000 pulses were given in each session: one trial before treatment (control or chiropractic) and one trial after the treatment.

The entire spine and both sacroiliac joints were assessed for segmental dysfunction and adjusted where they were deemed necessary by an experienced chiropractor. Assessment for dysfunction included tenderness to palpation of the relevant joints, restricted intersegmental range of motion, asymmetric muscle tension, and any abnormal or blocked joint play and end-feel of the joints. The control (sham) involved one of the investigators (not a chiropractor) simulating a chiropractic treatment session. This included passive and active movements of the subject’s head, spine, and body, similar to what was done by the chiropractor who provided the actual chiropractic treatment.

Results:

  • SEPs were successfully recorded in all subjects
  • the majority of subjects were able to correctly guess which intervention group they were in (SM or sham)
  • there was a significant post-intervention difference between the two groups – specifically the N30 amplitude was reduced in the spinal manipulation group following the treatment, while it remained stable in the control group
  • source localization indicated that the prefrontal cortex tended to have the highest strength during the time interval between 20 and 60 ms
  • source strength analysis revealed that chiropractic treatment reduced the strength of the prefrontal source, while all the other strengths remained stable

Key Points:

  • Results from this study confirmed that spinal manipulation of dysfunctional spinal segments reduces the N30 SEP peak amplitude and demonstrated that this change is taking place in the prefrontal cortex
  • This suggests that, at least in part, the mechanisms by which spinal manipulation improves performance are due to a change in function at the prefrontal cortex
  • It is possible that the mechanisms behind pain relief following spinal manipulation in low level pain patients are due to improved sensorimotor integration and appropriate motor control, as this is the key function of the prefrontal cortex

Source: Lelic D, Niazi IK, Holt K, Jochumsen M, Dremstrup K, Yielder P, Murphy B, Drewes AM, Haavik H. Manipulation of Dysfunctional Spinal Joints Affects Sensorimotor Integration in the Prefrontal Cortex: A Brain Source Localization Study. Neural Plast. 2016;2016:3704964.

 

35856944_sResearch on chiropractic spinal manipulation (CSM) has been conducted extensively worldwide, and its efficacy on musculoskeletal symptoms has been well documented.  Previous studies have documented potential relationships between spinal dysfunction and the autonomic nervous system and that chiropractic treatment affects the autonomic nervous system. The authors of this study hypothesized that CSM might induce metabolic changes in brain regions associated with autonomic nervous system functions as assessed with positron emission tomography (PET).  Positron emission tomography is a nuclear medicine imaging technique that allows quantification of cellular and molecular processes in humans such as cerebral glucose metabolism which is thought to reflect regional neuronal activities.

Participants were men between the ages of 20-40 who had neck pain and shoulder stiffness.

A crossover study design was used such that subjects served as their own controls to compare their resting brain activity to their brain activity following chiropractic manipulation.  Half of the participants completed the control condition first while the other half completed the chiropractic condition first.  The participants came back sometime between 1 and 6 weeks later to complete their remainder condition.  Chiropractic consisted of a single Activator Methods assessment and treatment session by a chiropractor lasting 20 minutes.  The control condition consisted of 20 minutes of rest.  Immediately after each condition, 18F-labeled fluorodeoxyglucose (FDG) was injected.  FDG is an excellent imaging marker of brain metabolism (glucose consumption).  PET scanning followed administration of FDG.

Additional outcome measures included pain (VAS), Stress Response Scale (SRS-18) and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30), trapezius muscle tone, and salivary amylase.

Results of the PET image analysis showed statistically significant changes in regional cerebral metabolism between rest and treatment conditions.  With chiropractic treatment, increased glucose metabolism was observed in the inferior prefrontal cortex, anterior cingulate cortex,  middle temporal gyrus; decreased glucose metabolism was observed in the cerebellar vermis and visual association cortex.  Reduced metabolism in the cerebellar vermis may be related to reductions is pain, mental stress, muscle tone and sympathetic tone.  Activation of the anterior cingulated cortex and inferior prefrontal cortex may arise from sympathetic relaxation.

The mean SRS-18 and EORTC QLQ-C30 scores were significantly lower in the treatment condition indicating improved stress response and improved quality of life. Mean VAS pain score comparison was significantly improved with treatment.  Additionally, measurement of trapezius muscle tone and salivary amylase showed significant reduction with chiropractic suggesting improved sympathetic relaxation.

 

Reference: Tashiro M, Ogura T, Masud M, Watanuki S, Shibuya K, Yamaguchi K, Itoh M, Fukuda H, Yanai K. Cerebral metabolic changes in men after chiropractic spinal manipulation for neck pain. Altern Ther Health Med. 2011 Nov-Dec;17(6):12-7.

 

 

Episode

In this episode, Dr. Meier discusses how people move differently in the presence of (or in anticipation of) pain. Changes in motor control may play an important role in musculoskeletal pain. His lab uses a cross-disciplinary approach that combines neuroscience and movement biomechanics to provide new insights into the role of potential interactions between movement behavior, psychological factors and supraspinal mechanisms in the development and maintenance of persistent low back pain. We’ll touch also on fear avoidance and pain related movement avoidance.  Dr. Michael L. Meier is a senior pain researcher and group leader at the Department of Chiropractic Medicine at the University of Zurich. He received his master’s degree in neuropsychology and his doctorate in cognitive neuroscience from the University of Zurich, focusing on the processing of pain and nociception in the brain. In 2019, he received a grant from the Swiss National Science Foundation (SNF) to study the role of movement behavior and cortical processes in the development and persistence of low back pain. A hallmark of his work is linking research from different disciplines such as biomechanics, neuroscience, and psychology, shedding light on novel interacting pathomechanisms underlying persistent low back pain whose pathoanatomical cause is often unclear.

Please see Dr. Michael Meier’s research profile at researchgate.net.  Further information and links to his research can be found at the Balgrist University Hospital website.

Below are the articles Dr. Michael Meier and I discuss in this episode:

1.
Fear-avoidance beliefs are associated with reduced lumbar spine flexion during object lifting in pain-free adults.
Knechtle D, Schmid S, Suter M, Riner F, Moschini G, Senteler M, Schweinhardt P, Meier ML.
Pain. 2021 Jun 1;162(6):1621-1631. doi: 10.1097/j.pain.0000000000002170.
PMID: 33323888 Free PMC article.
2.
Neural responses of posterior to anterior movement on lumbar vertebrae: a functional magnetic resonance imaging study.
Meier ML, Hotz-Boendermaker S, Boendermaker B, Luechinger R, Humphreys BK.
J Manipulative Physiol Ther. 2014 Jan;37(1):32-41. doi: 10.1016/j.jmpt.2013.09.004. Epub 2013 Nov 12.
PMID: 24229849
3. Identifying Motor Control Strategies and Their Role in Low Back Pain: A Cross-Disciplinary Approach Bridging Neurosciences With Movement Biomechanics.
Schmid Stefan, Bangerter Christian, Schweinhardt Petra, Meier Michael L.
Frontiers in Pain Research. 2021 Aug;(2):42. doi: 10.3389/fpain.2021.715219
Drs. Imran Niazi and Kelly Holt

Drs. Imran Niazi and Kelly Holt discuss with me their research on chiropractic, falls risk, and neuroplasticity in various populations. Imran Khan Niazi received his B.Sc. degree in Electrical engineering (specialisation: Biomedical Engineering) from the Riphah International University, Islamabad, Pakistan, in 2005, and his  Masters in biomedical engineering from University & FH Luebeck, Luebeck, Germany in 2009. Later he got his PhD under the supervision of Prof. Dario Farina from Center of sensory-motor interaction, Health Science Technology Department, University of Aalborg, Aalborg, Denmark in 2012. After working as a postdoc for a year, he moved to New Zealand in 2013, where he is currently working as Senior Research Fellow at New Zealand College of Chiropractic. He has an adjunct position in Aalborg University, Denmark and Auckland University of Technology, New Zealand.

Dr. Niazi is interested in studying and understanding the altered mechanism of motor control and learning in neurological disorder to develop various technologies that can enhance the QOL of these patients. He has successfully co-supervised 4 PhD and 31 master thesis and currently has 4 active PhD students. He has authored 46 peer-reviewed journal papers and 82 conference papers (proceedings and extended abstracts including). His work has been cited more than 1100 times, and have an h-index of 16 according to google scholar. Over the last ten year, he has received funding worth around US $ 1.5 million from various sources. He is currently working as a review editor for Frontiers in Robotics and AI (Biomedical Robotics) and reviewer for more than 25 engineering/neuroscience journals.

Dr. Kelly Holt was a member of the 1998 inaugural graduating class of the New Zealand College of Chiropractic. Besides his chiropractic degree he also holds a Bachelor of Science majoring in physiology and a PhD in Health Science from the University of Auckland. His PhD focused on the effects of chiropractic care on sensorimotor function and falls risk in older adults. He has published work in a number of peer reviewed journals that investigated the effects of chiropractic care on nervous system function and the reliability of vertebral subluxation indicators and has won a number of international research awards. Kelly worked in private practice as a chiropractor for 10 years following graduation and has taught at the New Zealand College of Chiropractic since 2000 and is currently the Dean of Research at the College.   Kelly was named ‘Chiropractor of the Year’ by the New Zealand College of Chiropractic Alumni Association in 2012 and by the New Zealand Chiropractors’ Association in 2014.

View Dr. Imran Niazi’s research at researchgate.net and Dr. Kelly Holt’s research at researchgate.net.

In addition to Drs. Imran Niazi and Kelly Holt, you might also be interested in listening to the previous episode with Dr. Heidi Haavik, also from New Zealand College of Chiropractic discussing “brain adjustments”.

Below are the studies that we discuss in this interview.

1. The effects of a single session of chiropractic care on strength, cortical drive, and spinal excitability in stroke patients.
  Holt K, Niazi IK, Nedergaard RW, Duehr J, Amjad I, Shafique M, Anwar MN, Ndetan H, Turker KS, Haavik H.
  Sci Rep. 2019 Feb 25;9(1):2673. doi: 10.1038/s41598-019-39577-5.
  PMID: 30804399 [PubMed – in process] Free PMC Article
  Similar articles
2. The effects of a single session of spinal manipulation on strength and cortical drive in athletes.
  Christiansen TL, Niazi IK, Holt K, Nedergaard RW, Duehr J, Allen K, Marshall P, Türker KS, Hartvigsen J, Haavik H.
  Eur J Appl Physiol. 2018 Apr;118(4):737-749. doi: 10.1007/s00421-018-3799-x. Epub 2018 Jan 11.
  PMID: 29327170 [PubMed – indexed for MEDLINE] Free PMC Article
  Similar articles
3. Effectiveness of Chiropractic Care to Improve Sensorimotor Function Associated With Falls Risk in Older People: A Randomized Controlled Trial.
  Holt KR, Haavik H, Lee AC, Murphy B, Elley CR.
  J Manipulative Physiol Ther. 2016 May;39(4):267-78. doi: 10.1016/j.jmpt.2016.02.003. Epub 2016 Apr 2.
  PMID: 27050038 [PubMed – indexed for MEDLINE]
  Similar articles
4. Changes in H-reflex and V-waves following spinal manipulation.
  Niazi IK, Türker KS, Flavel S, Kinget M, Duehr J, Haavik H.
  Exp Brain Res. 2015 Apr;233(4):1165-73. doi: 10.1007/s00221-014-4193-5. Epub 2015 Jan 13.
  PMID: 25579661 [PubMed – indexed for MEDLINE]
  Similar articles

Geoffrey Bove, DC, PhD, and I discuss his research regarding inflammation within peripheral nerves, chiropractic principles, manual therapies, repetitive motion disorders and much more.  Dr. Bove is a graduate of Hampshire College, Canadian Memorial Chiropractic College, and the University of North Carolina, Chapel Hill.  He is currently a professor at the University of New England, in Biddeford Maine (USA).  Dr. Bove’s research has focused on the effect of inflammation on small diameter axons within peripheral nerves, a topic directed by founding chiropractic principles.  He also studies the effects of manual therapies on common painful conditions, such as repetitive motion disorders and postoperative visceral adhesions.

Visit Dr. Bove’s research gate profile.

Here are the links to Dr. Bove’s articles we discuss in this interview:

 

1. Time course of ongoing activity during neuritis and following axonal transport disruption.
Satkeviciute I, Goodwin G, Bove GM, Dilley A.
J Neurophysiol. 2018 May 1;119(5):1993-2000. doi: 10.1152/jn.00882.2017. Epub 2018 Feb 21.
PMID: 29465329 [PubMed – in process]
Similar articles
2. Group IV nociceptors develop axonal chemical sensitivity during neuritis and following treatment of the sciatic nerve with vinblastine.
Govea RM, Barbe MF, Bove GM.
J Neurophysiol. 2017 Oct 1;118(4):2103-2109. doi: 10.1152/jn.00395.2017. Epub 2017 Jul 12.
PMID: 28701542 [PubMed – indexed for MEDLINE] Free PMC Article
Similar articles
3. Attenuation of postoperative adhesions using a modeled manual therapy.
Bove GM, Chapelle SL, Hanlon KE, Diamond MP, Mokler DJ.
PLoS One. 2017 Jun 2;12(6):e0178407. doi: 10.1371/journal.pone.0178407. eCollection 2017.
PMID: 28574997 [PubMed – indexed for MEDLINE] Free PMC Article
Similar articles
4. A model for radiating leg pain of endometriosis.
Bove GM.
J Bodyw Mov Ther. 2016 Oct;20(4):931-936. doi: 10.1016/j.jbmt.2016.04.013. Epub 2016 Apr 14.
PMID: 27814877 [PubMed – indexed for MEDLINE] Free PMC Article
Similar articles
5. A Novel Method for Evaluating Postoperative Adhesions in Rats.
Bove GM, Chapelle SL, Boyle E, Mokler DJ, Hartvigsen J.
J Invest Surg. 2017 Apr;30(2):88-94. doi: 10.1080/08941939.2016.1229367. Epub 2016 Oct 3.
PMID: 27690703 [PubMed – indexed for MEDLINE]
Similar articles
6. Manual therapy as an effective treatment for fibrosis in a rat model of upper extremity overuse injury.
Bove GM, Harris MY, Zhao H, Barbe MF.
J Neurol Sci. 2016 Feb 15;361:168-80. doi: 10.1016/j.jns.2015.12.029. Epub 2015 Dec 24.
PMID: 26810536 [PubMed – indexed for MEDLINE] Free PMC Article
Similar articles
7. Disruption of fast axonal transport in the rat induces behavioral changes consistent with neuropathic pain.
Dilley A, Richards N, Pulman KG, Bove GM.
J Pain. 2013 Nov;14(11):1437-49. doi: 10.1016/j.jpain.2013.07.005. Epub 2013 Sep 12.
PMID: 24035352 [PubMed – indexed for MEDLINE]
Similar articles
8. Focal nerve inflammation induces neuronal signs consistent with symptoms of early complex regional pain syndromes.
Bove GM.
Exp Neurol. 2009 Sep;219(1):223-7. doi: 10.1016/j.expneurol.2009.05.024. Epub 2009 May 27.
PMID: 19477176 [PubMed – indexed for MEDLINE]
Similar articles
9. Inflammation induces ectopic mechanical sensitivity in axons of nociceptors innervating deep tissues.
Bove GM, Ransil BJ, Lin HC, Leem JG.
J Neurophysiol. 2003 Sep;90(3):1949-55. Epub 2003 Apr 30.
PMID: 12724363 [PubMed – indexed for MEDLINE] Free Article
Similar articles
10. Disruption of axoplasmic transport induces mechanical sensitivity in intact rat C-fibre nociceptor axons.
Dilley A, Bove GM.
J Physiol. 2008 Jan 15;586(2):593-604. Epub 2007 Nov 15.
PMID: 18006580 [PubMed – indexed for MEDLINE] Free PMC Article
Similar articles

HeidiHaavik
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Learn what happens in your brain when a chiropractor adjusts your spine.  Dr Heidi Haavik is a chiropractor and a neurophysiologist who has worked in the area of human neurophysiology for over 15 years. Heidi has a PhD in human neurophysiology from the University of Auckland. Her work has been instrumental in building the base of scientific evidence demonstrating the efficacy of chiropractic care in improving people’s health and wellbeing. As a researcher, she has investigated the effects of chiropractic adjustments of dysfunctional spinal segments (vertebral subluxations) on somatosensory processing, sensorimotor integration and motor cortical output.

Dr Haavik is the Director of Research at the New Zealand College of Chiropractic where she has established the Centre for Chiropractic Research. Dr Haavik is also an Adjunct Professor at the University of Ontario, Institute of Technology in Oshawa, Canada and is a member of the World Federation of Chiropractic’s Research Council. Dr Haavik has received numerous research awards and has published a number of papers in chiropractic and neurophysiology journals. She has presented her work to both chiropractic and neuroscience communities around Australasia, North America and Europe. She is on the Editorial Board of the Journal of Manipulative and Physiological Therapeutics and Journal of Chiropractic Education. She was named Chiropractor of the year in 2007 by both the New Zealand Chiropractic Association and the New Zealand College of Chiropractic Alumni Association.  She is also the author of a textbook – The Reality Check which describes in easy to understand language what happens in the brain when a chiropractor adjusts dysfunctional segments in your spine.

Read about Dr Haavik at her website, and get her book and posters at heidihaavik.com.  Subscribe to Dr Haavik’s research service at haavikresearch.com to get great evidence-informed marketing material for chiropractic practices including among other things, videos for your website that explain how chiropractic works.  Interested in donating toward her research efforts?  Contact her at haavikresearch.com.

HeidiDean2015

Dr. Haavik and Dr. Smith at the Ohio State Chiropractic Association Convention, 2015

reality check

Dr. Haavik’s book: The Reality Check