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The Chiropractic Impact Report

Courtesy of: Joseph Penge, D.C.

November 2022

Neck Injury and the Brain

Background Information

Mild traumatic brain injuries are also known as concussions. It is estimated that these injuries have a prevalence of 3.8 million per year in the United States (1). Despite this high incidence, mild traumatic brain injuries and concussions are one of the least understood injuries facing the sports healthcare and the neuroscience communities today (2).


Sir Isaac Newton (1643-1727) explained the three universal laws of motion in his 1687 book Mathematical Principles of Natural Philosophy. Newton’s first law of motion states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This tendency to resist changes in a state of motion is termed inertia.

The inertial tendency of an object is proportional to the object’s weight. The greater the weight, the greater the inertia. As an analogy, it is more difficult to change the resting state of a 100-pound rock as compared to that of a 10-pound rock. It is also more difficult to stop the uniform motion of a 100-pound rock as compared to that of a 10-pound rock.

Newton’s Law of Inertia applies to the human body. Different parts of the human body have different inertias between them. Of particular importance is the inertial differences between the human head and the person’s trunk.

Neck Hyperextension As Trunk Is Pushed Under Head

A classic example of these inertial concepts is the rear-end motor vehicle collision. In a rear-end motor vehicle collision, the struck vehicle, its seat, and trunk of the occupant are quickly propelled forward, while the head, having its own inertial mass, will remain at rest. Thus, the head remains still while the body is moved forward under the head. This gives the appearance that the head is extending upon the trunk, the so-called “hyperextension” phase of a rear-end motor vehicle collision.

Other inertial differences within the human body, pertinent to this discussion, are between the skull and the brain, and between the brain and the spinal cord.

Two Types of Brain Injury

(please forgive the crassness of the analogy)


The stationary head can be injured by a direct blow. The head might be struck by a hammer, bat, or a falling object. The skull will hopefully protect the brain from injury by dispersing the forces of the blow.

Wearing a hard-hat or a helmet adds to the protection of the brain by enhancing the dispersion of the forces from the blow. Hence, the ubiquitous advocacy of helmet wearing throughout society, from sports to family bike riding, etc.

Direct blow brain injury can occur without direct injury to the neck. It can also occur without any inertial injury to the neck, to the brain, and/or to the spinal cord.

Direct blow brain injury is only rarely encountered in chiropractic clinical practice.


The brain can sustain an inertial injury. Inertial brain injury can occur without any blow to the head/skull. The injury occurs as a consequence of the brain smashing into the inside of the skull.

A societally understood but horrific example of inertial brain injury is shaken baby syndrome. The violent shaking of a baby causes serious inertial injuries (including death) to the baby’s brain, spinal cord, and neck. Yet, often there is no direct blow to the baby’s head, neck, or body.

Brain inertial injuries are the rule in motor vehicle collisions and in most of sport’s head trauma.

Elite athletes can run 100 yards in 10 seconds, traveling about 20 miles per hour. The athlete’s body, neck, spinal cord, brain, and skull are all moving together at 20 miles per hour.  Should the athlete collide with a wall, goal post, another player, etc., and his/her body fully stop in a fraction of a second, the brain in the skull will continue to propel forward at the pre-collision 20 miles per hour because of the law of inertia. The brain will collide with the inside of the skull and sustain an inertial injury.

Importantly, this inertial brain injury will occur whether the athlete is wearing a helmet or not. Ironically, wearing a helmet adds to the weight of the head, increasing its inertia. Increasing the weight of the head with a helmet increases the inertial loads and injuries to the neck. Helmets primarily protect against direct blow head/skull injuries. Helmets increase neck inertial injuries. As noted below, helmets increase brain inertial injuries:

Give an elite football player (American) the best helmet available. Ask the player to run as fast as he is comfortable and crash his helmet, head first, into a brick wall. How fast will he run?

Remove the helmet from the player and again ask him to run as fast as he is comfortable and crash his head, without a helmet, into a brick wall. How fast will he run?

Important Points:

When it comes to crashing one’s head into a brick wall, the player with the helmet will run faster towards the wall.

  • Using the helmet will reduce direct blow brain injury. This is good.
  • Using the helmet, because of the faster running speed, will increase inertial brain injury. This is not

In vivo, the brain is exceptionally soft, delicate, and vulnerable. The outside of the skull is mostly smooth. However, the inside of the skull is not smooth. Inside the skull there are numerous sharp and jagged bony contours and ridges. Inertial stress between the skull and the brain rakes the soft brain over the bony ridges, resulting in appreciable damage.

Key Points:

One can sustain a direct blow brain injury without sustaining an inertial injury to the neck, brain, and/or spinal cord.

Essentially all inertial brain injuries will also cause an inertial injury to the neck and its structures, including the joints, discs, muscles, nerves, and potentially the spinal cord.

Clinical Diagnosing of Inertial Brain Injury

The most widely accepted criteria for traumatic brain injury are from the American Congress of Rehabilitation Medicine, which include (3):

  • Any period of loss of consciousness.
  • Any loss of memory for events immediately before or after the accident (posttraumatic amnesia).
  • Any alteration in mental state at the time of the accident, including feeling dazed, disoriented, or confused.
  • Any focal neurological deficits that may or may not be transient but that do not exceed: loss of consciousness of 30 minutes; an initial Glasgow Coma Scale (GCS) score of 13-15 (explained below); posttraumatic amnesia of 24 hours.

This definition includes these mechanisms of injury:

  • The head being struck.
  • The head striking an object.
  • The brain undergoing an acceleration/deceleration movement (i.e.,whiplash) without direct external trauma to the head.


The Glasgow Coma Scale (GCS) is a neurological scale used to give a reliable and objective assessment of the conscious state of a person, adult or child, primarily following head injury. It was published in 1974 by professors of neurosurgery at the University of Glasgow’s Institute of Neurological Sciences (4):

GCS less than 8–9         Severe Brain Injury

GCS 9–12           Moderate Brain Injury

GCS 13-15          Minor Brain Injury

  • The scale is composed of three tests: eye, verbal, and motor
  • A score of 15 is essentially normal, a fully awake person.
  • A score of 3 indicates a deep coma.

A copy of the Glasgow Coma Scale is included at the end of this paper.


Recovery from traumatic brain injury is measured using two outcomes:

 Functional Recovery

Subjective (symptom) Recovery


Functional recovery is assessed using the Glasgow Outcome Scale-Extended (GOS-E) score (5). This tool for functional recovery is the most widely used outcome measure in traumatic brain injury and is widely recommended by international bodies, including the National Institutes of Health:

  • full functional recovery = GOS-E score of 8
  • incomplete recovery = GOS-E score less than 8: 1 indicates death; 4 indicates severe disability; 5 indicates moderate disability; 7 indicates unable to return to preinjury functioning; 8 indicates full recovery or return to baseline function

A copy of the GOS-E is included at the end of this paper.


Subjective (symptom) Recovery is assessed using the Rivermead Post Concussion Symptoms Questionnaire (RPQ) (6). The RPQ asks about 16 new or worsened symptoms since the injury; scores range from 0 (best) to 64 (worst).

A copy of the Rivermead Post Concussion Symptoms Questionnaire is included at the end of this paper.


A recent study (August 2022) looked at the long-term (6 month) recovery rates in individuals who had sustained a mild traumatic brain injury. The study was published in the Journal of the American Medical Association Network Open and titled (7):

Outcomes in Patients with Mild Traumatic Brain Injury

Without Acute Intracranial Traumatic Injury

The objective of this study was to describe the 2-week and 6-month recovery outcomes in a cohort of 991 patients with mild traumatic brain injury, a Glasgow Coma Scale score of 15, and a negative head CT scan that had been taken within 24 hours of injury. Subjects’ mean age was 39 years, 64% male and 36% female. As noted above, patient assessments were done using:

Glasgow Coma Scale for severity of injury.

Glasgow Outcome Scale-Extended for functional recovery.

 Rivermead Post Concussion Symptoms Questionnaire for subjective (symptom) recovery.

The authors note that most of the more than 3 million new cases of traumatic brain injury in the United States each year are classified as mild.

Medical care practitioners often assume that patients with mild traumatic brain injury will improve over time with the only intervention being rest, and there will be no long-term sequelae.

Despite such optimism, 21% of patients with mild traumatic brain injury “will experience mental health problems, including posttraumatic stress disorder and depression; cognitive and behavioral impairment; and changes in memory, attention, and motivation, which are associated with loss of work days and unemployment.”

The outcomes presented in this prospective study of nearly 1,000 subjects is summarized in the chart below (7):

GOS-E Score at 2 Weeks

Increased RPQ Symptoms at 2 Weeks

Increased RPQ Symptoms at 6 Months













GOS-E Score at 6 Months

Increased RPQ Symptoms at 6 Months









Two weeks after the injury, 27% had functional recovery and 73% had incomplete recovery.

Six months after the injury, 44% had functional recovery and 56% had incomplete recovery. More than half of the patients who sustained a mind traumatic brain injury with a negative CT scan had not functionally recovered 6 months after injury.

Only 12% of the patients noted meaningful subjective recovery between 2 weeks and 6 months, indicating that a “wait and see” management is certainly inadequate for these patients.

In this cohort of mild brain injured subjects, the majority were neither functionally or subjectively recovered at 6 months after injury. The authors state:

“This study found that most [mild traumatic brain injury] participants with a GCS score of 15 and negative head CT scan reported incomplete recovery at 2 weeks and 6 months after their injury.”

Traumatic Brain Injury and the Neck

In 2015, an important study on this topic was published in the journal The Physician and Sports Medicine, and titled (8):

The Role of the Cervical Spine in Post-concussion Syndrome

The authors note that there is considerable overlap of the signs and symptoms of mild traumatic brain injury and of whiplash neck injury. This overlap of presentation may cause confusion as to the source of symptomatology. A “wait and see” approach to management of an assumed brain injury may be completely inappropriate if in fact the symptoms are attributed to the neck.

This paper reviews the existing literature surrounding the numerous proposed theories of post-concussive syndrome and introduces another potential, and very treatable, cause of this chronic condition: cervical spine dysfunction due to concomitant whiplash-type injury.

The authors provide a comparative chart contrasting mild traumatic brain injury with whiplash neck injury:

Signs and Symptoms of Mild Traumatic Brain Injury

Signs and Symptoms of Whiplash Injuries


Pressure in Head


Neck pain

Neck/shoulder pain

Reduced/painful neck movements




Balance problems



Blurred Vision

Sensitivity to Light

Vision problems

Difficulty remembering


Feeling Like “In a Fog”

Difficulty Concentrating

Memory problems

Problems Concentrating

Sensitivity to Noise

Ringing in Ears

Feeling Slowed Down

“Don’t Feel Right”

Nervous / Anxious / Irritable

Sadness / More Emotional

Fatigue / Low Energy /Drowsiness

Trouble Falling Asleep

Reduced/painful Jaw Movements

Numbness, Tingling or Pain in Arm or Hand

Numbness, Tingling or Pain in Leg or Foot

Difficulty Swallowing

The symptoms of headache and dizziness that are so prevalent in concussion-type injuries may actually be the result of neck injury mechanisms. Numerous brain stem structures receive synaptic inputs from the second cervical dorsal root ganglion afferents, including (9):

  • Lateral cervical nucleus
  • Central cervical nucleus
  • Caudal projections to C5 level
  • Cuneate nucleus, lateral cuneate nucleus
  • Nucleus tractus solitarius
  • Intercalatus nucleus
  • Nucleus X of the vestibular system
  • Trigemino-cervical nucleus

In this article, the authors discuss the cases of 5 patients with diagnosed post-concussive syndrome, who experienced very favorable outcomes following various treatment and rehabilitative techniques aimed at restoring cervical spine function. The treatment included chiropractic spinal manipulation.

These authors propose that a cervical injury, suffered concurrently at the time of the mild traumatic brain injury, acts as a “major symptomatic culprit in many post-concussive syndrome patients.”

These authors state:

“Any significant blunt impact and/or acceleration/deceleration of the head will also result in some degree of inertial loading of the neck potentially resulting in strain injuries to the soft tissues and joints of the cervical spine.”

 “Acceleration/deceleration of the head–neck complex of sufficient magnitude to cause mild traumatic brain injury is also likely to cause concurrent injury to the joints and soft tissues of the cervical spine.”

“[It is] well established that injury and/or dysfunction of the cervical spine can result in numerous signs and symptoms synonymous with concussion, including headaches, dizziness, as well as cognitive and visual dysfunction, making diagnosis difficult.”

It has been known since 2006 that brain-injured athletes concurrently injure their cervical spines (10). Injury or dysfunction of the cervical spine has been shown to cause headaches, dizziness and loss of balance, nausea, visual and auditory disturbances, reduced cognitive function, and many other signs and symptoms considered synonymous with concussion.

In this study (8), the authors present five cases of patients diagnosed with post-concussive syndrome who were treated successfully in a chiropractic clinic. Their improvement was rapid and documented using standard measurement outcomes. The improved clinical outcome results were long-lasting.

The treatment included:

  • Active Release Therapy
  • Localized vibration therapy over the affected muscles
  • Spinal manipulative therapy of the restricted joints
  • Low-velocity mobilizations (on 1 patient)

The authors concluded:

“Management of persistent post concussive symptoms through ongoing brain rest is outdated and demonstrates limited evidence of effectiveness in these patients.”

“[Instead, there is evidence that] skilled, manual therapy- related assessment and rehabilitation of cervical spine dysfunction should be considered for chronic symptoms following concussion injuries.”

This study highlights the lack of understanding by athletes, the public, and healthcare providers that it is essentially impossible to sustain a traumatic brain injury without also injuring the soft tissues of the cervical spine. It is anatomically and biologically probable that these cervical spine injuries cause many, if not most, of the symptoms of the post-concussion syndrome.

It is gratifying to see a published study showing that traditional chiropractic management of post-concussive syndrome patients resulted in rapid and sustained improvement in post-concussive signs and symptoms, allowing the athlete to return to full competition.

It is recommended that all patients who are likely suffering from a mild traumatic brain injury be referred to a chiropractor for cervical spine evaluation and treatment. This is especially important in light of the poor functional and subjective outcomes associated with the “wait and see” approach to management (7).

It is also recommended that all patients suffering from the post-concussive syndrome (long-term sequelae to mild traumatic brain injury) should be referred to a chiropractor for cervical spine evaluation and treatment.


  1. Langlois JA, Rutland-Brown W, Wald MM; The Epidemiology and Impact of Traumatic Brain Injury: A Brief Overview; Journal of Head Trauma Rehabilitation; September-October 2006; Vol. 21; No. 5; pp. 375–378.
  2. Thompson J, Sebastianelli W, Slobounov S; EEG and Postural Correlates of Mild Traumatic Brain Injury in Athletes; Neuroscience Letters; April 4, 2005; Vol. 377; No. 5; pp. 158–163.
  3. Kay T, Harrington DE, Adams R, et. al; Definition of Mild Traumatic Brain Injury; Journal of Head Trauma and Rehabilitation; 1993; Vol. 8; No. 3; pp. 86-87.
  4. Teasdale G, Jennett B; Assessment of Coma and Impaired Consciousness: A Practical Scale; Lancet; July 13, 1974; Vol. 304; No. 7872; pp. 81-84.
  5. Wilson JT, Pettigrew LE, Teasdale G; Structured Interviews for the Glasgow Outcome Scale and the Extended Glasgow Outcome Scale: Guidelines for Their Use; Journal of Neurotrauma; August 1998; Vol. 15; No. 8; pp. 573-585.
  6. King NS, Crawford S, Wenden FJ, Moss NE, Wade DT; The Rivermead Post-concussion Symptoms Questionnaire: A Measure of Symptoms Commonly Experienced After Head Injury and its Reliability; Journal of Neurology; September 1995; Vol. 242; No. 9; pp. 587-592.
  7. Madhok DY, Rodriguez RM, Barber J, Temkin NR, Markowitz AJ, Kreitzer N, Manley GT; Outcomes in Patients with Mild Traumatic Brain Injury Without Acute Intracranial Traumatic Injury; JAMA Network Open; August 1, 2022; Vol. 5; No. 8; Article e2223245.
  8. Marshall CM, Vernon H, Leddy JJ, Baldwin BA; The Role of the Cervical Spine in Post-concussion Syndrome; July 2015; Vol. 43; No. 3; pp. 274-284.
  9. Bogduk N; Anatomy and Physiology of Headache; Biomedicine and Pharmacotherapy; 1995; Vol. 49; No. 10; pp. 435-445.
  10. Hynes LM, Dickey JP; Is there a Relationship Between Whiplash-Associated Disorders and Concussion in Hockey?; Brain Injury; February 2006; Vol. 20; No. 2; pp. 179-188.

“Authored by Dan Murphy, D.C.. Published by ChiroTrust® – This publication is not meant to offer treatment advice or protocols. Cited material is not necessarily the opinion of the author or publisher.”

GLASGOW COMA SCALE: the highest possible score is 15:

Eye Opening 

  1. Never (no eye opening)
  2. To Pain Stimulus (squeezing the lunula area of the patient’s fingernail)
  3. To Sound, specifically to speech
  4. Spontaneous

Verbal Responses 

  1. None
  2. Incomprehensible Sounds (moaning but no words)
  3. Inappropriate Words (random or exclamatory speech, but no conversational exchange; speaks words but no sentences)
  4. Confused Conversation (The patient responds to questions coherently but there is some disorientation and confusion)
  5. Oriented (Patient responds coherently and appropriately to questions such as the patient’s name and age, where they are and why, the year, month, etc.)

Motor Responses

  1. None, no motor response
  2. Extension Response – Decerebrate posturing (adduction of arm, internal rotation of shoulder, pronation of forearm and extension at elbow, flexion of wrist and
  3. fingers, leg extension, plantar-flexion of foot)
  4. Abnormal Flexion Response – Decorticate posturing (internal rotation of shoulder, flexion of forearm and wrist with clenched fist, leg extension, plantar-flexion of foot)
  5. Normal Flexion (withdrawal) – Withdrawal from pain (absence of abnormal posturing; unable to lift hand past chin with supraorbital pressure pain applied;
  6. but does pull away when nailbed is pinched)
  7. Localizes Pain – Localizes to pain (purposeful movements towards painful stimuli; e.g., brings hand up beyond chin when supraorbital pressure applied)
  8. Obeys commands (the patient does simple things as asked)

The Glasgow Outcome Scale-Extended (GOS-E)

  1. Dead
  1. Vegetative – Condition of unawareness with only reflex responses but with periods of spontaneous eye opening.
  1. Lower Severe Disability – Patient fully dependent for all activities of daily living; Requires assistance to be available constantly; Unable to be left alone at night.
  1. Upper Severe Disability – Can be left alone at home for up to 8 hours but remains dependent. Unable to use public transport or shop by themselves.
  1. Lower Moderate Disability – Able to return to work in sheltered workshop or non-competitive job. Rarely participates in social and leisure activities. Ongoing daily psychological problems (quick temper, anxiety, mood swings, depression).
  1. Upper Moderate Disability – Able to return to work. Participates in social and leisure activities less than half as often. Weekly psychological problems.
  1. Lower Good Recovery – Returned to work. Participates in social and leisure activities a little less and has occasional psychological problems.
  1. Upper Good Recovery – Full recovery with no current problems relating to injury.

The Rivermead Post-Concussion Symptoms Questionnaire

Please compare yourself now (in the last 24 hours) with before the accident:

  • 0 = Not experienced at all
  • 1 = Not more of a problem
  • 2 = A mild problem
  • 3 = A moderate problem
  • 4 = A severe problem

Headaches………………………………………….. 0 1 2 3 4

Feelings of Dizziness ………………………………0 1 2 3 4

Nausea and/or Vomiting …………………………. 0 1 2 3 4

Noise Sensitivity, easily upset by loud noise ….0 1 2 3 4

Sleep Disturbance ………………………………….0 1 2 3 4

Fatigue, tiring more easily ………………………..0 1 2 3 4

Being Irritable, easily angered …………………..0 1 2 3 4

Feeling Depressed or Tearful …………………….0 1 2 3 4

Feeling Frustrated or Impatient …………………0 1 2 3 4

Forgetfulness, poor memory …………………….0 1 2 3 4

Poor Concentration ………………………………. 0 1 2 3 4

Taking Longer to Think ………………………….. 0 1 2 3 4

Blurred Vision …………………………………….. 0 1 2 3 4

Light Sensitivity, easily upset by bright light …0 1 2 3 4

Double Vision ………………………………………0 1 2 3 4

Restlessness ……………………………………….0 1 2 3 4

Are you experiencing any other difficulties?

  1. __________________________________ 0 1 2 3 4
  1. __________________________________ 0 1 2 3 4