The Chiropractic Adjustment Changes Brain Function
The Evidence of Increased Muscle Strength is Added to Pain Sensitivity and Autonomic Changes
Mark Studin DC, FASBE(C), DAAPM, DAAMLP
William J. Owens DC, DAAMLP
Matt Erickson DC, FSBT
A report on the scientific literature
There is a growing body of evidence that a high-velocity, low-amplitude (HVLA) chiropractic spinal adjustment (CSA) has a significant influence on cortical (brain) and other central (cord) changes. This is significant as the evidence is now answering more questions on why has chiropractic has had such a profound effect on a myriad of conditions beyond back pain. Technology, including but not limited to functional MRI, NCV, EEG and sEMG renders demonstrable validation of the effect the chiropractic spinal adjustment has on changes in central function.
A chiropractic spinal manipulation/adjustment is a specific HVLA thrust maneuver designed to correct spinal patho-neuro-biomechanics (remove nerve irritation/interference, restore biomechanical balance), increases important proteins such as Substance P (Evans 2002) and makes plastic changes to the central nervous system. Conversely, a spinal manipulation as manual therapy or thrust joint manipulation (TJM) performed by physical therapists (PT’s) is a generalized non-specific low-velocity, low-amplitude of non-specific HVLA thrust maneuver of joints and connective tissue to improve motion and decrease muscle tension.
Essentially, the intent of TJM is in treating pain and dysfunction. That is not to say a non-specific manipulation will not help a patient. However, when spinal manipulation is not performed as a chiropractic based neuro-biomechanical corrective adjustment or from a salutogenic health management perspective, it is something else entirely. Therefore, spinal manipulation as a chiropractic adjustment delivered by a chiropractor is not synonymous with TJM, mobilization or spinal manipulation delivered by a PT.
Reed, Pickar, Sozio, and Long (2014) reported, “.forms of manual therapy have been clinically shown to increase mechanical pressure pain thresholds (i.e., decrease sensitivity) in both symptomatic and asymptomatic subjects. Cervical spinal manipulation (chiropractic HVLA) has been shown to result in unilateral as well as bilateral mechanical hypoalgesia. Compared with no manual therapy, oscillatory spinal manual therapy at T12 and L4 produced significantly higher paraspinal pain thresholds at T6, L1, and L3 in individuals with rheumatoid arthritis. The immediate and widespread hypoalgesia associated with manual therapy treatments has been attributed to alterations in peripheral and/or central pain processing including activation of descending pain inhibitory systems. Increasing evidence from animal models suggests that manual therapy activates the central nervous system and, in so doing, affects areas well beyond those being treated. (p. 277)
Reed et al. (2014) also reported, The finding that only the higher intensity manipulative stimulus (ie, 85% BW [body weight] vs 55% BW or control) decreased the mechanical sensitivity of lateral thalamic neurons to mechanical trunk stimulation coincides with other reports relating graded mechanical or electrical stimulus intensity to the magnitude of central inhibition. Several clinical studies indicate that spinal manipulation [chiropractic spinal adjustment] alters central processing of mechanical stimuli evidenced by increased pressure pain thresholds and decreased pain sensitivity in asymptomatic and symptomatic subjects following manipulation. (p. 282)
Daligadu, Haavik, Yielder, Baarbe, and Murphy (2013) reported, There is also evidence in the literature to suggest that muscle impairment occurs early in the history of onset of spinal complaints, and that such muscle impairment does not automatically resolve even when pain symptoms improve. This has led some authors to suggest that the deficits in proprioception and motor control, rather than the pain itself, may be the main factors defining the clinical picture and chronicity of various chronic pain conditions. Furthermore, recent evidence has demonstrated that spinal manipulation (CSA) can alter neuromuscular and proprioceptive function in patients with neck and back pain as well as in asymptomatic participants. For instance, cervical spine manipulation (CSA) has been shown to produce greater changes in pressure pain threshold in lateral epicondylalgia than thoracic manipulation; and in asymptomatic patients, lumbar spine manipulation (CSA) was found to significantly influence corticospinal and spinal reflex excitability. Interestingly, Soon et al did not find neurophysiological changes following mobilization on motor function and pressure pain threshold in asymptomatic individuals, perhaps suggesting that manipulation [chiropractic spinal adjustments], as distinct from mobilization, induces unique physiological changes. There is also accumulating evidence to suggest that chiropractic manipulation can result in changes to central nervous system function including reflex excitability, cognitive processing, sensory processing, and motor output. There is also evidence in SCNP [sub-clinical neck pain] individuals that chiropractic manipulation alters cortical somatosensory processing and elbow joint position sense. This evidence suggests that chiropractic manipulation may have a positive neuromodulatory effect on the central nervous system, and this may play a role in the effect it has in the treatment of neck pain. It is hoped improving our understanding of the neurophysiological mechanisms that may precede the development of chronic neck pain in individuals with sub-clinical neck pain (SCNP) will help provide a neurophysiological marker of altered sensory processing that could help determine if an individual is showing evidence of disordered sensorimotor integration and thus might benefit from early intervention to prevent the progression of SCNP into more long-term pain states. (p. 528)
Christriansen, Niazi, Holt, Nedergaard, Duehr, Allen, Marshall, Turker and Haarvik (2018) discussed the effects of a single session of a chiropractic spinal manipulation (CSA) on strength and cortical drive. They studied the effects upwards of 60 minutes and further testing is needed to determine the long-term effects of the adjustment. They found in “blinded studies” that “the increased maximum voluntary contraction force lasted for 30 min and the corticospinal excitability increase persisted for at least 60 minutes.” (pg. 737)
Christiansen et. Al (2018) also reported, “The increased V-wave amplitudes observed in the current study possibly reflect an increased cortical drive in the corticospinal pathways and corresponding increased excitability of the MNs following SM found differences in the cortical drive in volleyball athletes competing at different levels, and argued that elite players had increased cortical drive correlating to their biomechanical performance. The absence of change in the H-reflex in the presence of the increased MVC along with increased V-waves suggests that it's possible that the change post manipulation occurred at supraspinal centers involving a cortical neural drive. The V-waves represent cortical drive. The absence of change in the H-reflex alone suggests that the spinal motor neurons and the excitability of the spindle primary afferent synapses on the spinal motor neurons did not change as a result of SM.” (pg. 745) The above paragraph indicates there is no input at the cord level as the H-Reflex exhibited no changes.
Increased motor function for a minimum of 60 minutes post-chiropractic spinal adjustment has far-reaching manifestations for a dichotomy of the population. Athletes at every level will benefit from increased motor function and patients suffering from either muscular or neuro-degenerative illnesses, such as Parkinson’s, Amyotrophic lateral sclerosis (ALS), Muscular Dystrophy and others will also potentially benefit. Although this article touched on PT manual therapy, low-velocity, low-amplitude or non-specific thrust joint manipulation; these forms of treatment do not render the outcomes a chiropractic spinal adjustment.
Christiansen et. Al (2018) concluded and perfectly positioned the effect of a chiropractic spinal adjustment and the effect on the brain, “this study supports a growing body of research that suggests chiropractic spinal manipulation’s main effect is neuroplastic in nature and affects corticospinal excitability. Changes in both cerebellum and prefrontal cortex function have been implicated post-spinal manipulation in previous research studies. The presence of mild, recurrent spinal dysfunction has been shown to be associated with maladaptive neural plastic changes, such as alterations in elbow joint position sense mental rotation ability, and even multisensory integration Furthermore, spinal manipulation of dysfunctional spinal segments has been shown to impact somatosensory processing, sensorimotor integration and motor control.” (pg. 746)
Diagnosis & Collaborative Management Between the Chiropractor as the Primary Spine Care Provider and the Neurosurgeon
By: Matt Erickson DC, FSBT
Mark Studin DC, FASBE(C), DAAPM, DAAMLP
John Edwards MD, Neurosurgeon
Clay Wickiser DC
is defined as softening of the spinal cord and can be a result of injury and represents a serious and potentially life-threatening sequella to injury if not treated. According to Zhou, Kim, Vo and Riew (2015), “Cervical myelomalacia is a relatively uncommon finding on MRI, with anoverall prevalence of 4.2% among all patients who underwent cervical MRI. Males had a higher prevalence (5.6%) than the females (3.0%).” (pg. E250)
Zhou et al., (2015) also reported, “There were considerable variations in the prevalence of myelomalacia in patients referred by different specialties/subspecialties. Specialists in spinal cord injury had the highest rate (28.7%), followed by neurological (8.4%) and orthopedic (6.4%) spine surgeons, general neurosurgeons (5.5%), and neurologists (4.2%). Specialists who generally do not treat patients with spine problems had the lowest (1.2%) followed by non-spine orthopedists (1.6%) and primary care doctors (2.1%)” (p. E248).
Myelomalacia is ischemic or hemorrhagic necrosis of the spinal cord that can occur following acute spinal cord injury, and represents extensive damage of the intramedullary spinal vasculature” (pg. 78). According to “In small animal neurology, the term myelomalacia … is normally used to refer to hemorrhagic infarction of the spinal cord that can occur as a sequel to acute injuries, such as that caused by intervertebral disc extrusion. Myelomalacia may occur as a focal lesion or may spread cranially and caudally along the spinal cord, resulting in a diffuse, severe lesion. Histologic lesions of myelomalacia are compatible with ischemic necrosis” (pg. 326).
According to a website article titled, “Myelomalacia” by Foster and Wilborn (2019), “Myelomalacia is a medical condition in which the spinal cord becomes soft. It is caused by the insufficient blood supply to the spinal cord, either as a result of bleeding or because of poor circulation. Myelomalacia most often occurs as a result of the injury” (www.wisegeek.com/what-is-myelomalacia.htm). Foster and Wilborn (2019) added, “Caused by mild to severe spinal cord injury, myelomalacia leads to neurological problems, often related to muscle movement. Often, the onset of the condition is slow and subtle, making it difficult for doctors to catch at an early stage. The condition may present simply as high blood pressure, for example, and may not be diagnosed until after the point at which it has become inoperable. While symptoms vary, they may include loss of motor function in the lower extremities, sudden jerking of the limbs, an inability to sense pain, depression, difficulty breathing, and paralysis. The damage can migrate towards the brain in a condition known as ascending syndrome. Myelomalacia can be fatal if it causes paralysis of the respiratory system (para. 2-3).
, “The exact pathophysiology is poorly understood but it seems to be the result of the concussive effects of trauma, ischemia, and the release of vasoactive substances, oxygen-free radicals and cellular enzymes. When the spinal cord is acutely damaged, cell death in the gray matter may occur within 4 hours, with this area of necrosis expanding for a few days” (pg. 78). This means that many patients can have significant underlying progressive pathology with symptoms that have not yet fully expressed themselves, but the evidence is demonstrative to the trained expert. This further supports the necessity and importance of having a primary spine care provider with trauma qualifications to diagnose the issue early on and coordinate care with the neurosurgeon.
Operative Neurosurgery, “Myelomalacia” (administrator updated) (2018, para. 4), explained, “Gradual cranial migration of the neurological deficits (problems relating to the nervous system), is known as ascending syndrome and is said to be a typical feature of diffuse myelomalacia. Although clinical signs of myelomalacia are observed within the onset (start) of paraplegia, sometimes they may become evident only in the post-operative period, or even days after the onset of paraplegia. Death from myelomalacia may occur as a result of respiratory paralysis when the ascending lesion (abnormal damaged tissue) reaches the motor nuclei of the phrenic nerves (nerves between the C3-C5 region of the spine) in the cervical (neck) region” (https://operativeneurosurgery.com/doku.php?id=myelomalacia).
As such, it is imperative for there to be collaborative case management between the primary spine care expert and the neurosurgeon. The role of the primary spine care provider is an early diagnosis to be able to identify, treat and involve the neurosurgeon when clinically indicated because if left undiagnosed and untreated, myelomalacia can become a seriously debilitating and/or life-threatening injury. Those injuries are from and trauma the spinal cord is exposed to (auto accidents, sports injuries, falls, etc.). Currently, there is a growing body of chiropractors nationally that are primary spine care and trauma qualified and trained in the early detection (diagnosis) and management of this population of patients.
According to Zohrabian and Flanders, Chapter 37: Imaging of trauma of the spine from the Handbook of Clinical Neurology Part II, “MRI is the only available imaging modality that is able to clearly depict the internal architecture of the spine cord, and, as such, has a central role in depicting parenchymal changes resulting from injury” (pg. 760). Further, “It may be difficult to distinguish spinal cord white matter from gray matter, especially in the sagittal plane, due to the similar T1 and T2 relaxation characteristics. Many prior investigations have shown that MRI characteristics of (SCI) Spinal Cord Injury, including presence and extent of cord edema and hemorrhage, are concordant with neurologic impairment at the time of injury and predict recovery” (pg.760).
Zohrabian and Flanders also wrote, “The most common location of posttraumatic spinal cord hemorrhage is the central gray matter of the spinal cord at the point of mechanical impact. The lesion most often represents hemorrhagic necrosis; true hematomyelia is rarely encountered. The lesion appears as a discrete focus of hypointensity on T2-weighted and gradient echo images, developing rapidly after SCI” (pg.760).
Zohrabian and Flanders (2016) stated, “Moreover, the location of cord hemorrhage has been shown to closely correspond to the neurologic level of injury, with frank hemorrhage correlation with poor neurologic recovery” (p. 760).
Zohrabian and Flanders (2016) further added, “Although several MRI classification schemes have been proposed, there are three common imaging observations: spinal cord hemorrhage, spinal cord edema, and spinal cord swelling. Each of these characteristics can be further described by their rostra-caudal (top to bottom) location in the cord and the amount of cord parenchyma they involve” (p. 760).
“Spinal cord edema, colloquially referred to as a cord contusion, can occur with or without hemorrhage. Edema involves a length of the spinal cord above and below the level of injury, with the length of the spinal cord show to be proportional to the degree of initial neurologic deficit. Spinal cord hemorrhage always coexists with spinal cord edema. Cord edema alone usually confers a more favorable prognosis that cord hemorrhage” (pg. 761).
According to D.J. Seidenwurm MD (, “In traumatic myelopathy, the first priority is mechanical stability. Plain radiographs are sometimes useful for this purpose, but CT is more useful when a high probability of bony injury or ligamentous injury is present. In many centers, routine multidetector CT with sagittal and coronal reconstructions has replaced plain radiographs, especially in the setting of multiple trauma” (pg. 1032).
Concerning CT, Foster and Wilborn (2019) reported, “Myelography uses a contrast medium injected into the spine to reveal injuries in x-rays. It is more invasive than an MRI, but can also detect injury in some cases in which MRI cannot. Therefore, myelography is typically used as a follow up to MRI when the latter fails to identify the source of pain or injury.” (para. 4)Finally, Zohrabian and Flanders reported, “Unlike in spinal cord cysts, myelomalacia will not parallel CSF (cerebral spinal fluid) signal intensity and its margins will usually be irregular and ill-defined (Falcone et al., 1994). The cord may be normal in size, although it is frequently atrophic at the site of myelomalacia (Fig. 37.24).” (pg. 763)
Zhou, Kim and Vo (2015) further explain, “Myelomalacia is a radiographical finding on magnetic resonance imaging (MRI) manifested by an ill-defined area of cord signal change, visible on T1- and T2-weighted sequences as hypo- and hyperintense areas, respectively. It is commonly associated with focal cord atrophy. It occurs as a sequel to spinal cord injury (SCI) due to different causes such as cord compression, ischemia, and hemorrhage. It is the most common finding in patients with previous spinal cord injury with a prevalence of 55% among patients with SCI” (p. E248).
Due to the seriousness and progressive nature of myelomalacia, it is important for the Primary Spine Care Provider, to recognize the signs and symptoms associated with myelomalacia and to identify the lesion on MRI and if identified, immediately refer the patient for a neurosurgical consultation. This also underscores why physical therapists, although licensed to treat spine, should never be the first provider to manage a spine case as diagnosing these and other conditions are not within their scope.
Foster and Wilborn (2019, para. 5) also reported, “Unfortunately, neurological damage due to myelomalacia is permanent. It can also worsen, as the nerve damage can cause affected muscles to whither. Treatment is focused on preventing further damage. Possible treatments include spinal cord surgery and medication with steroids, which serves to relax spastic muscles, reduce pain, and reduce swelling of the spinal cord.” Foster and Wilborn (2019, para. 6) also suggested, “Stem cell therapy may be used to repair neurological damage caused by myelomalacia in the future, but the therapy is currently experimental and controversial. Recent technology suggests that adult stem cells, which can be harvested from the patient's own body, show promise in treating neurological damage by allowing new, healthy tissue to grow”(www.wisegeek.com/what-is-myelomalacia.htm).
Zhou, Kim, Vo and Riew (2015) reported, “The presence of myelomalacia in the cervical spinal cord has prognostic value after decompression surgery. Some surgeons consider operative treatment of all patients with myelomalacia based on the assumption that myelomalacia is a relatively uncommon finding.” (p. E248) The authors also reported, “Many patients with myelomalacia are clinically asymptomatic or have only mild myelopathic symptoms and signs. The extent of intramedullary changes on MRI does not always correlate with clinical symptoms. Hence, for patients with asymptomatic or mild myelopathy with myelomalacia on MRI, the appropriate management remains controversial” (p. E249).
Zhou et al (2015) further added, “Several articles have suggested that conservative management is not an unreasonable option for patients with myelomalacia and mild myelopathy. It has been reported that the condition of 56% of patients with mild CSM (cervical spine myelomalacia) had not deteriorated or required surgery after 10 years. However, 2 of 45 (4.4%) patients who were treated nonoperatively with T2 hyperintensities experienced catastrophic neurological deficits with trivial trauma. Early-stage myelomalacia may be reversible, depending on the severity of the initial SCI (spinal cord injury), and may be reversed after decompression surgery” (p. E249).
This is not suggesting surgery for myelomalacia is always required. According to Dr. Mark Kotter (n.d., para. 3) in a website article titled “Myelomalacia” from myelopathy.org,“The presence or absence of myelomalacia should not be used to define when surgery should occur.” Although he further stated, “its presence and extent may be related to prognosis” (http://www.myelopathy.org/myelomalacia.html). Myelomalacia, like any spinal related injury never uses imaging findings exclusively as an arbiter for surgery. That decision is reserved for combining a clinical examination with imaging findings and the surgeon decides if surgery will benefit the patient. It is the role of the primary spine care provider to ensure and early diagnosis and referral to try to develop treatment protocols to surgically decompress the spinal cord to help reverse this pathology and often can be done if damage has been minimized.
Surgery for Myelomalacia
A patient with myelomalacia may require surgery to decompress the spinal cord. Different techniques are used depending on the pathology that may or may not include spinal fusion. Many patients are treated with an anterior approach. The offending material is removed and the spine is reconstructed either with a fusion or an artificial disc replacement. Some patients, especially with multilevel pathology, require posterior decompression with or without fusion.
The primary goal of surgery for myelomalacia is to decompress the spinal cord. Secondary goals include maintaining spinal structural integrity, alignment, and biomechanical function.
The image on the left is courtesy of Jed Weber MD, Neurosurgeon. You can see the severe spinal cord compression creating an hour glass affect secondary to a disc extrusion. Myelomalacia is also present as a white spot in the spinal cord at the compression site.
Concerning surgically balancing the spine, sagittal (front to back) balance is associated with better post-surgical outcomes. Healia.com reported on lectures by Serena Hu, MD, Jean Charles LeHuec, MD, PhD and J.N. Alastair Gibson, MD, FRCS(Ed), FRCS (Tr &Orth), MFSTEd related to outcomes of lumbar spine surgery about sagittal balance. According to Dr. Hu (2016, para 3), “Surgical outcomes for spine surgery are improved when spinal, pelvic and hip alignment is considered in both degenerate and deformity cases, and how we better understand these will help us better improve outcomes for our patients” (https://www.healio.com/spine-surgery/lumbar/news/print/spine-surgery-today/%7B54ac5ca2-7939-407d-96a5-31fa9c0fc904%7D/proper-sagittal-balance-may-correlate-with-better-surgical-outcomes).
Dr. Hu (2016) further reported, “Sagittal imbalance in a patient can negatively affect the outcomes of a surgical procedure. But, how extensive the surgery required is to correct the imbalance must be carefully considered for the individual patient” (para. 4). Dr. LeHuec (2016) added, “Sagittal balance is an active phenomenon for patients. “The best course of action is to strive to achieve sagittal balance in patients” (para. 8).
In a study by
In an article by Yeh, Lee, Chen, Yu, Liu, Peng, Wang, and Wu, (2018) they concluded, “The results of this study support previous findings that functional outcomes are closely associated with sagittal radiographic parameters in the patients with the degenerative thoracolumbar spinal disease who received long-segment fusion. The achievement of global and regional sagittal alignment balance is a crucial factor for improved postoperative functional outcomes” (p. 1361).
The primary care spine provider and the neurosurgeon can work together to best achieve spinal alignment and balance. If the patient has been cleared for mechanical treatment, the primary care spine provider can work to balance the spine (front to back and side to side) before any necessary surgical intervention. The neurosurgeon can work to maintain and improve spinal alignment with surgery. Post-operatively, ongoing chiropractic spinal adjustments can help maintain and continue to improve spinal alignment. This can lead to the best possible surgical outcomes.
Patients with myelomalacia present an ideal opportunity to further the relationship between the Doctor of Chiropractic as the primary care spine provider and the neurosurgeon. The finding of myelomalacia requires surgical consultation. If the chiropractor identifies myelomalacia, he or she can then refer to the neurosurgeon and begin the discussion necessary for further co-management. The chiropractor can ask if surgery is necessary. If so, the Doctor of Chiropractic can ask if mechanical treatment can be done pre-operatively or ask if it should wait until after surgery. If the patient needs close monitoring over time, the astute chiropractor can regularly check on and provide education to the patient under the direction of the neurosurgeon.
In patients with myelomalacia, the ability of the Doctor of Chiropractic to monitor symptoms, prepare a patient for surgery, and manage the spine mechanically after surgery are advantageous to the surgeon, who can spend more of their time performing surgery and also enjoy greater patient satisfaction and outcomes.
Myelomalacia represents a softening of the spinal cord that commonly results from trauma. If myelomalacia is observed on imaging, the advanced trained Doctor of Chiropractic in the capacity of a primary spine care provider, should refer the patient out for a neurosurgical consultation. In the event surgery is not indicated, the chiropractor can create a treatment plan with the surgeon to help axially balance and stabilized the spine, thereby reducing the compressive forces on the spinal cord and maintaining spinal mechanics. If surgery is required, the chiropractor can coordinate conservative care with the surgeon to help biomechanically balance and then manage the patient’s spine to promote a better long term post-surgical outcome. Whether surgical or not, the chiropractor can play an integral role in the patient’s car and should the chiropractor have additional training in MRI Spine Interpretation, Spinal Biomechanical Engineering and/or other advanced spinal knowledge, it provides the basis for better collaboration.