Neurology of the Upper Cervical Subluxation

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Neurology of the Upper Cervical Subluxation
2
Subluxation

• sub Less Than
• Luxatio Dislocation
• less than a dislocation
• Medical use of the term traced back to 1688 by
  Holme. a dislocation or putting out of joint

Henderson, C. Subluxation Theory. Lyceum 2000
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Subluxation

• 1934 Subluxation Specific, BJ Palmer
• A vertebral subluxation is any vertebra out of
  normal alignment, out of apposition to its
  co-respondents above and below, wherein it does
  occlude a foreman, either spinal or
  intervertebral, which does produce pressure upon
  nerves, thereby interfering and interrupting the
  normal quantity flow of mental impulse supply
  between brain and body and thus becomes THE CAUSE
  of all dis-ease.

Henderson, C. Subluxation Theory. Lyceum 2000
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Subluxation

• ACA and ICA adopted definition
• A motion segment in which alignment, movement
  integrity, and/or physiologic function are
  altered although contact between the joint
  surfaces remains intact.

Henderson, C. Subluxation Theory. Lyceum 2000
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Subluxation

• A complex of function and/or structural and/or
  pathological articular changes that compromise
  neural integrity and may influence organ system
  function and general health.
• Association of Chiropractic Colleges

Owens, E. J Can Chiropr Assoc 200246(4)
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Neurology of the Upper Cervical Subluxation

• It has been shown that the average
  occipito-atlantal misalignment in the frontal
  plane is almost 3, which equates to about 1/8 of
  an inch of linear movement.
• This is significant because the upper cervical
  spinal cord has a diameter of about half an inch.

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Neurology of the Upper Cervical Subluxation

• The upper cervical spinal cord is directly
  attached to
• the circumference of the foramen magnum,
• the second and third cervical vertebrae,
• posterior longitudinal ligament
• The dentate ligaments are 21 paired lateral bands
  of epipial tissue midway between the dorsal and
  ventral attachments of the nerve roots.
• The medial border of the dentate ligaments is
  continuous with the pia mater of the spinal cord
  and attaches to the dura mater laterally.

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Neurology of the Upper Cervical Subluxation

• The rectus capitis posterior minor muscle
  attaches to the dura mater of the upper cervical
  spinal cord.
• Attachment have also been found to the spinal
  cord via
• the ligamentum nuchae
• epidural ligaments

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Neurology of the Upper Cervical Subluxation

• Neurological dysfunction may occur via two
  mechanisms
• direct mechanical irritation of the nerves of the
  spinal cord
• The collapse of the small veins of the cord
  producing venous congestion

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The Spinocerebellar tracts

• The spinocerebellar tracts lie along the lateral
  edge of the spinal cord (the most probable site
  of maximal mechanical irritation by the dentate
  ligaments).
• Proprioceptive tracts, which regulates muscle
  tone and joint position sense.
• Irritation of these tracts could lead to muscle
  tone imbalance of the pelvic girdle resulting in
  a functional short leg.

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The Spinothalamic Tracts

• Close to the attachment of the dentate ligaments.
• Responsible for conveying pain and temperature
  into the neuroaxis.
• Mechanical irritation and/or ischemic compromise
  to the spinothalamic tracts possibly explains
  particular cases of severe low back and leg pain
  being caused by an upper cervical subluxation.

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MECHANORECEPTIVE DYSAFFERENTATION

• Mechanoreceptors are so named because they are
  activated by mechanical deformation.
• The mechanoreceptors are primarily responsible
  for the body's position sense within the gravity
  environment.
• Provide information orientating the head with
  respect to the body to maintain equilibrium.

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The vestibular apparatus (VA)

• Informs the brain of the head's position and
  works to keep it perpendicular with the ground by
  altering the tone of the cervical muscles.
• The most important proprioceptive information
  required for the maintenance of equilibrium is
  derived from joint receptors of the neck. Guyton

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Mechanoreceptors

• Type I provide important information about joint
  position as they signal the angle of the
  articulation throughout the range of motion.
• Type II Have a low threshold and rapidly adapt
  to a stimulus. Detect rate of movement at the
  articulation.
• Type III High threshold and slowly adapting
  receptors. They are stimulated only at the
  extremes of joint movement. Structurally similar
  to the Golgi tendon organ of the muscular system
• Type IV Nociceptors have a high threshold and
  do not adapt. These pain receptors tend to be
  free nerve endings.

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Mechanoreceptors

• The cervical spine has more mechanoreceptors, per
  surface area, than any other region of the spinal
  column.

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Model for the receptor activity in the normal,
nondysfunctional state (no abnormal vertebral
position or particular hypomobility or
hypermobility).
Normal physiological pressure and tension on
fibrous joint capsule
Correct anatomical position of vertebra(e)
Resting muscle tone equilibrium between
synergists and antagonists
Mechanoreceptors and nociceptors are inactive
No pain perception
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Model for receptor activity as a result of
vertebral segmental dysfunction (abnormal
vertebral position and/or somatic dysfunction
with pain and hypomobility, etc.).
Irritation of fibrous joint capsule
Abnormal position of vertebra(e) Segmental
dysfunction
Stimulation of mechanoreceptors of type 1
Tonic-reflexogenic influence on motor neurons of
neck, limb, jaw, eye muscles (myotendinoses)

Stimulation of Nociceptors
Additional impulses (mechanical, chemical)
Spinothalamic tract
Pain perception
Spinal Adjustment
Correction of segmental dysfunction
Stimulation of mechanoreceptors type II
inhibition of afferent fibers release of
enkephalins
Less pain, normalization of receptor activity
Change toward normal muscle tone
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The Postural Spondylogenic Reflex Syndrome
Clinical Correlation with Reflexes Linked to
Nociceptors and Mechanoreceptors

• The clinical symptom of pain in muscles and other
  soft tissues (spontaneous or elicited by
  palpatory pressure) has been termed the
  Spondylogenic Reflex Syndrome by Sutter
  (1974,1975).
• Myotendinoses has been in observe the various
  systematic response to an articular/somatic
  dysfunction involving the individual apophyseal,
  occipito-atlanto-axial, and sacroiliac joints.
• Many systematic myotendinoses improve during the
  course of therapeutic intervention in the
  individual patients.
• It was therefore assumed that, in addition to
  other helpful physical and therapeutic
  procedures, the mechanical and functional
  correction of the spinal motion unit, according
  to Schmorl and Junghanns (1968), can play a
  significant role, if not the most crucial role in
  treatment.

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The Postural Spondylogenic Reflex Syndrome

• The absence of pain does not automatically mean
  lack of soft-tissue findings.
• It is well known that localized palpable muscle
  bands or systematic myotendinoses can be elicited
  upon careful palpation in many individuals who
  have no subjective pain complaints.
• This situation is to be considered pathologic and
  correlates with the latent state of
  intervertebral insufficiency according to Schmorl
  and Junghanns (1968).
• This could be explained on the basis of the tonic
  reflexogenic influence of the type 1
  mechanoreceptors upon the motor neurons of the
  axial or peripheral musculature.
• It has been shown that pain-inducing nociceptors
  have significantly higher thresholds than
  pain-inhibiting mechanoreceptors. This may
  explain the delay with which the individual may
  perceive his or her pain.

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The Postural Spondylogenic Reflex Syndrome

• The nociceptive stimulation can be inhibited
  presynaptically when there is sufficient
  stimulation of the mechanoreceptors, mainly the
  type II receptors.
• This may occur by release of endorphins cells in
  the gelatinous substance of the dorsal horns.
• Therefore, it would plausible to propose that
  these and probably other related neurophysiologic
  mechanisms may play at least as important a role
  in manual therapeutic treatment as the pure
  mechanical correction of one or several segmental
  dysfunctions.

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The Postural Spondylogenic Reflex Syndrome
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Force of the UC Adjustment

• Depending upon the type of cervical manipulative
  technique used, preload forces range from 0 to
  approximately 50 N, and peak impulse forces range
  from approximately 40 N to approximately 120 N.
• The forces delivered during cervical
  manipulations develop faster than during
  manipulation of the thoracic spine and sacroiliac
  joint.
• Impulse duration lasts from approximately 30 ms
  to approximately 120 ms.

J.G. Pickar / The Spine Journal 2 (2002) 357371
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Mechanical Forces from the Adjustment

• The mechanical force introduced into the
  vertebral column during a spinal manipulation may
  directly alter segmental biomechanics by
• releasing trapped meniscoids,
• releasing adhesions
• or by reducing distortion
• the mechanical input may ultimately reduce
  nociceptive input from receptive nerve endings in
  innervated paraspinal tissues.

J.G. Pickar / The Spine Journal 2 (2002) 357371
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Neurology of the Chiropractic Adjustment

• The mechanical thrust could either stimulate or
  silence non-nociceptive, mechano-sensitive
  receptive nerve endings in paraspinal tissues,
  including skin, muscle, tendons, ligaments, facet
  joints and intervertebral disc.
• These neural inputs may influence pain producing
  mechanisms as well as other physiological systems
  controlled or influenced by the nervous system.
• These changes in sensory input are thought to
  modify neural integration either by directly
  affecting reflex activity and/or by affecting
  central neural integration within motor,
  nociceptive and possibly autonomic neuronal
  pools.
• Either of these changes in sensory input may
  elicit changes in efferent somatomotor and
  visceromotor activity.

J.G. Pickar / The Spine Journal 2 (2002) 357371
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UC Subluxation and Neurologic Compromise

• Dentate Ligament Cord Distortion
• Medullary Lock Kessinger
• Sensory Neurologic Feedback
• Central Sensitization

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Dentate Ligament Cord Distortion Medullary Lock

• The upper cervical spinal cord is directly
  attached to
• the circumference of the foramen magnum,
• the second and third cervical vertebrae,
• posterior longitudinal ligament

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Dentate Ligament Cord Distortion

• The dura mater is a strong, fibrous membrane
  which forms a wide, tubular sheath this sheath
  extends below the termination of the medulla
  spinalis and ends in a pointed cul-de-sac at the
  level of the lower border of the second sacral
  vertebra.
• The dura mater is separated from the wall of the
  vertebral canal by the epidural cavity, which
  contains a quantity of loose areolar tissue and a
  plexus of veins between the dura mater and the
  subjacent arachnoid is a capillary interval, the
  subdural cavity, which contains a small quantity
  of fluid, probably of the nature of lymph.
• The arachnoid is a thin, transparent sheath,
  separated from the pia mater by a comparatively
  wide interval, the subarachnoid cavity, which is
  filled with cerebrospinal fluid.
• The pia mater closely invests the medulla
  spinalis and sends delicate septa into its
  substance a narrow band, the ligamentum
  denticulatum, extends along each of its lateral
  surfaces and is attached by a series of pointed
  processes to the inner surface of the dura mater.

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Dentate Ligament Cord Distortion

• the strongest ligaments are in the upper cervical
  region
• short, thick, and pass almost perpendicularly
  from the pia mater to their attachments on the
  dura mater.

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Dentate Ligament Cord Distortion

• The upper cervical area is the only area where in
  the dentate ligaments are perpendicular to the
  cord.
• From full extension and full flexion of the
  cervical spine the cervical canal length changes
  about 30 mm.
• during extension there is some compression of the
  cord, during flexion there is stretching of the
  cord

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Dentate Ligament Cord Distortion

• Based on these observations, it may be a primary
  role of the upper cervical Dentate ligaments to
  restrict the downward-pulling axial forces
  created by the lengthening of the canal when the
  neck is flexed from being transmitted
  unattenuated to the brainstem.
• JD Grostic

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Dentate Ligament Cord Distortion

• In normal flexion the dentate ligaments are
  strong enough to slightly deform the cord.
• Chronic tension on a ligament may produce
  thickening and strengthening of the ligament,
  decreasing the ligament's ability to damp the
  distortive forces before they can deform the
  cord. Kahn

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Dentate Ligament Cord Distortion

• Tension on the dentate ligaments may cause
  distortion to the spinal dura causing
• Mechanical irritation to the spinal tracts
• Spinal Cord Ischemia
• Tethering the Spinal cord

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Dentate Ligament Cord Distortion

• Mechanical irritation to the spinal tracts
• The spinocerebellar tracts (proprioception) are
  located at the site of maximal mechanical
  irritation.
• Spinal cord irritation by dentate ligament
  traction may cause hypertonicity and spasticity
  in the muscles of the pelvic girdle and lower
  extremities.

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Dentate Ligament Cord Distortion

• Mechanical irritation to the spinal tracts
• Pain in the low back and legs may be caused by
  mechanical irritation of the spinothalamic tract
  (pain, temperature, itch and crude touch) in the
  upper cervical cord due to traction of the
  dentate ligaments.
• The trigeminal nerve spinal nucleus may be
  tractioned by a lateral deviation and rotation of
  the atlas.

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Dentate Ligament Cord Distortion

• Spinal Cord Ischemia
• Dentate ligament may cause mechanical stresses to
  the cord.
• Mechanical obstruction of the veins of the upper
  cervical cord could cause stasis of blood and
  ischemia in the portion of the spinal cord
  drained by these veins.
• Venous stasis would tend to first cause ischemia
  in the lateral columns of the cord
• These veins operate at such low pressures and are
  easily occluded by compressive forces.
• Ischemia may first increases the irritability of
  nerves and increased sensitivity to the effects
  of mechanical irritation
• Jarzem et al. (1992) experimental cord
  distraction produced a decrease in spinal cord
  blood flow and concurrent interruption of
  somatosensory evoked potentials.

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Dentate Ligament Cord Distortion

• Tethering the Spinal cord
• The UC subluxation causing abnormal motion may
  cause a disruption of the normal function of the
  dentate ligaments which would not allow for full
  motion of the spinal cord during flexion and
  extension.
• Traction of the spinal cord will cause a decrease
  in the action potentials of spinal neurons.
• Mechanical deformation has shown to cause
  neurologic dysfunction.

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Sensory Neurologic Feedback

• After the intertransverse ligament at T3-T4 in
  4-week-old chickens was stretched mechanically
  and repeatedly for 60 minutes. Various areas of
  the nervous system then were sectioned and
  processed immunohistochemically to identify areas
  of Fos production in nerve cell bodies. The
  presence of Fos indicated neurons that had been
  stimulated by the stretching the ligament,
  including interneurons along the feedback
  pathway.
• The Fos protein was identified in nerve cell
  bodies in the dorsal root ganglia and
  intermediate gray matter of the spinal cord at
  the level of stimulation as well as at several
  spinal cord levels above and below the site of
  stimulation (on the ipsilateral and the
  contralateral sides), in sympathetic ganglia at
  these sites, nerve cell bodies in the combined
  nucleus cuneatus and gracilis in the medulla
  oblongata, the vestibular nuclei, and the
  thalamus.
• Stretching a single lateral ligament of the spine
  produces a barrage of sensory feedback from
  several spinal cord levels on both sides of the
  spinal cord.
• Information from this study allowed Jaing to
  trace the relay system of neurological afferent
  synapse through the CNS.

Jiang H. Spine. 22(1)17-25, January 1, 1997
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Sensory Neurologic Feedback

• The cervico-sympathetic reflex that can alter
  heart rate and blood pressure appears to
  originate from muscle spindles in the dorsal neck
  musculature, it is very likely that the
  suboccipital muscle group is involved in the
  reflex because these muscles have an extremely
  high muscle spindle content."
• "Additional evidence for the involvement of the
  suboccipital muscle group in the
  cervico-sympathetic reflex comes from changes in
  blood pressure associated with chiropractic
  manipulations of the C1 vertebrae, which would
  result in altering the length of fibers in the
  suboccipital muscle group."
• "The projection from the INTERMEDIATE NUCLEUS to
  the NUCLEUS TRACTUS SOLITARIUS identified in this
  study therefore places it in an ideal position to
  mediate cardiorespiratory changes to neck muscle
  afferent stimulation, because the NUCLEUS TRACTUS
  SOLITARIUS is a major integratory area for
  autonomic control circuits."

Ian J. The Journal of Neuroscience August 1,
2007 27(31) pp. 8324-8333
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Sensory Neurologic Feedback

• A theoretical model showing components that
  describe the relationships between spinal
  manipulation, segmental biomechanics, the nervous
  system and physiology.
• The neurophysiological effects of spinal
  manipulation could be mediated at any of the
  numbered boxes.

J.G. Pickar / The Spine Journal 2 (2002) 357371
40
Central sensitization

• debilitating fatigue, the majority of patients
  with chronic fatigue syndrome (CFS)
• Prolonged or strong activity of dorsal horn
  neurons caused by repeated or sustained noxious
  stimulation may subsequently lead to increased
  neuronal responsiveness or central sensitization
• These changes cause exaggerated perception of
  painful stimuli (hyperalgesia), a perception of
  innocuous stimuli as painful (allodynia) and may
  be involved in the generation of referred pain
  and hyperalgesia across multiple spinal segments

Mira Meeus Jo Nijs. Clin Rheumatol (2007)
26465473
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Central Sensitization

• Diseases Associated with Central Sensitization
  Syndrome
• Fibromyalgia
• Chronic fatigue syndrome
• Irritable bowel syndrome
• Depression
• Insomnia
• Abnormal Heart rate variability

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Central Sensitization

• AKA Central facilitation
• The increased excitability or enhanced
  responsiveness of dorsal horn neurons to an
  afferent input.
• Central facilitation can be manifested by
• increased spontaneous central neural activity,
• by enhanced discharge of central neurons to an
  afferent input
• by a change in the receptive field properties of
  central neurons.

J.G. Pickar / The Spine Journal 2 (2002) 357371
43
Central Sensitization

• Motoneurons could be held in a facilitated state
  because of sensory bombardment from segmentally
  related paraspinal structures.
• The motor reflex thresholds also correlated with
  pain thresholds, further suggesting that some
  sensory pathways were also sensitized or
  facilitated in the abnormal segment.

J.G. Pickar / The Spine Journal 2 (2002) 357371
44
Central Sensitization

• We currently know that the phenomenon of central
  facilitation increases the receptive field of
  central neurons and allows innocuous mechanical
  stimuli access to central pain pathways.
• In other words, subthreshold mechanical stimuli
  may initiate pain, because central neurons have
  become sensitized.
• Removal of these subthreshold stimuli should be
  clinically beneficial.
• One mechanism underlying the clinical effects of
  spinal manipulation may be the removal of
  subthreshold stimuli induced by changes in joint
  movement or joint play.

J.G. Pickar / The Spine Journal 2 (2002) 357371
45
Central Sensitization

• The dorsal horn is not simply a passive relay
  station for sensory messages but can modulate the
  messages as well.
• Natural activation of A-a and A-b fibers (like
  the spinal adjustment) has been shown to reduce
  chronic pain and increase pain threshold levels.

J.G. Pickar / The Spine Journal 2 (2002) 357371
46
Central Sensitization

• Spinal manipulation increased the average
  pressure/pain threshold of six tender spots in
  the neck region by approximately 50 (from 2
  kg/cm2 to 2.9 kg/cm2)
• The effect of spinal manipulation on pain could
  also be mediated by the neuroendocrine system.
  The endogenous opiate system is known to modify
  pain processes.

J.G. Pickar / The Spine Journal 2 (2002) 357371
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ALTERED SENSORIMOTOR INTEGRATION WITH
CERVICALSPINE MANIPULATION

• Spinal manipulation of dysfunctional cervical
  joints may alter specific central corticomotor
  facilitatory and inhibitory neural processing and
  cortical motor control.
• This suggests that spinal manipulation may alter
  sensorimotor integration.
• These findings may help elucidate the mechanisms
  responsible for the effective relief of pain and
  restoration of functional ability documented
  after spinal manipulation.

Haavik Taylor, Murphy. J Manipulative Physiol
Ther 200831115-126