Major Models and Hypotheses of Chiropractic Subluxation: II. Neurologic Models

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Major Models and Hypotheses of Chiropractic
Subluxation II. Neurologic Models
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• the central issues of chiropractic and manual
  medicine today concern the specific details
  ofneurological involvement in the subluxation
  complex rather than whether or not it exists.
• Charles Lantz

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Old Model (Murphy)
mechanical joint problem
DJD
radiculopathy and myelopathy
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New Model (Murphy)
mechanical joint problem
Chronically stressed tissues
Afferent discharge
Efferent reflex
Efferent discharge
Collagen breakdown
DJD
radiculopathy and myelopathy
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Three Types of Nerve Interference(Murphy)

• Reflex
• Irritation
• Compression

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New Model (Murphy)
mechanical joint problem
Chronically stressed tissues
Afferent discharge
Efferent reflex
Reflex nerve interference
Efferent discharge
Collagen breakdown
DJD
Irritation nerve interference
radiculopathy and myelopathy
Compression
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Major Neurological Theories(Haldeman)

• Receptor stimulation
• Nerve compression (traction)
• Reflex effects
• Supraspinal effects

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Reference re Neurologic Models

• Redwood Cleveland, Fundamentals of
  Chiropractic, 2003
• Chapter 8
• Neurobiologic
• Relations and Chiropractic Applications

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From Owens et al, Hypothesis Formulation for
Scientific Investigation of Vertebral
Subluxation, JVSR, 3(3), 1999, p. 100
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II. Neurological Models

• Nerve and Nerve Root Compression/Traction/Torsion
• aka compressive neuropathy

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Literature Review J. Vertebral Subluxation
Res., 4(2), 2001, pp. 37-48
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Nerve and Nerve Root Compression, Traction, and
Torsion

• IVF distortion due to VSC can cause mechanical
  compression of spinal nerves (neural complex)
  with resulting neurological injury and
  dysfunction
• Other mechanical changes can cause traction and
  torsion injuries to the neural complex
• neurothlipsis- pressure on a nerve, direct or
  indirect

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• To impinge upon a nerve is to press against it
  on one side. The impinging of nerves usually
  increases their function, because of irritation.
  Bones may be displaced, their projecting surfaces
  irritating the nerves which they strike against.
• D.D. Palmer

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• If we will use the word impingement in the sense
  of pressure and remember that an impingement
  instead of squeezing or pinching a nerve only
  increases its tension by stretching, we will have
  an explanation which will explain one which
  anatomists cannot gainsay.
• D.D. Palmer

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• nerves may be subject to stretch, constriction,
  compression, torsion, angulation, and ischemia.
• The predominant consequence of the more common
  and more subtle deforming forcesisnot the loss
  of excitability, but, on the contrary,
  hyperexcitability and the hyperirritability
  syndromes that it engenders.
• Irvin M. Korr, PhD

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Dorsal root ganglion (DRG)
Lateral horn
Dorsal root
Dorsal horn
IVF region
Spinal nerve
Ventral root
Anterior horn
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• Hadley found evidence that cervical and lumbar
  subluxations could produce foraminal encroachment
  that would cause or at least predispose the
  spinal nerve roots to compression. He also found
  that intervertebral subluxations could cause
  foraminal encroachment in the thoracic spine, but
  he determined that nerve root compression would
  be unlikely there due to the smaller diameter of
  the nerve roots.
• Leach, The Chiropractic Theories, p. 53

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• the only postmortem studies available indicate
  that subluxation is a factor in the compression
  of nerve roots and that the subsequent pathology
  depends on the severity of the compression.
  Pathophysiological features at the site of
  subluxation might include demyelination and
  degeneration of an individual fiber or groups of
  fibers, edema of the endoneurium, sclerosis of
  arterioles within the nerve bundle, and damage to
  the spinal ganglion itself.
• Leach, p. 57

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• Any abnormal constriction in the size of a
  normal intervertebral foramen if not actually
  causing nerve root pressure, nevertheless
  decreases the reserve safety cushion space
  surrounding that nerve and may predispose to
  pressure.
• Hadley

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Nerve Compression factors

• Subluxations cause spinal nerve root compression
  and injury (Hadley)

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Nerve Compression factors

• Nerve roots are susceptible to compression
  (Gelfan, Tarlov, Sharpless)

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Nerve Compression factors

• Nerve roots and sheath occupy 35-50 of IVF
  cross-sectional diameter remaining 50-65 is
  loose areolar connective tissue, adipose, other
  vascular and neural structures

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Nerve Compression factors

• Nerve roots lack the connective tissue sheath of
  peripheral nerves

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Nerve Compression factors

• Spinal distortion may displace neural complex
  laterally into the IVF by traction

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Transforaminal Ligaments (TFLs)

• accessory ligaments found to be normal
  occurrences throughout the spine locations
  variable in the IVF
• Especially common in lumbar spine- several at
  each level L5-S1 very prevalent
• They compartmentalize the IVF into a lattice that
  vessels and nerves must thread through
• May decrease the functional S to I diameter of
  the IVF by one-third

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Most Common Locations of Transforaminal Ligaments
(TFLs) in the IVF
Vertebral pedicle
Mixed Spinal Nerve in Dural Sleeve
TFLs
Vert. Body 1
Vein
Artery
IVD
Recurrent Meningeal Nerves
Vert. Body 2
Z-joint
Vertebral pedicle
Lymphatic vessel
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Ectopic Impulse Hypothesis (Korr)

• Deformation sites (as in the case of neurologic
  compression in the IVF) can be sites where
  ectopic nerve impulses are generated
• These are spontaneous depolarizations that give
  rise to both orthodromic (proper direction) and
  antidromic (wrong direction) impulses
• These have different effects if the involved
  nerves are sensory or motor

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Ectopic Nerve Impulses from Compression/Deformatio
n
Motor Nerve
Antidromic impulses
orthodromic impulses
Deformation Site
(MUSCLE)
Sensory Nerve
orthodromic impulses
Antidromic impulses
(SENSE ORGAN)
Deformation Site
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Ectopic Impulse Hypothesis (Korr), cont.

• Lateral transmission (ephaptic transmission, or
  cross-talk) can also occur at the deformation
  site
• The small electrical field changes that accompany
  a normally-propagated impulse can cause
  depolarization of adjacent axons at the
  deformation site again, antidromic and
  orthodromic ectopic impulses are generated

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II. Neurological Models

• Nerve and Nerve Root Compression/Traction/Torsion
• aka compressive neuropathy
• B. Dorsal Root Ganglion compression/irritation

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Dorsal Root Ganglion Compression

• Mechanical stresses due to VSC can cause injury
  to the highly sensitive DRG
• DRG are far more sensitive to mechanical
  stimulation than peripheral nerves (5X more
  sensitive to compressive forces)
• When inflamed, DRG become hyperexcitable, and can
  give rise to spontaneous discharges
• A significant irritating factor can be
  injury/inflammation/swelling in Z-joints

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Lateral horn
Dorsal root ganglion (DRG)
Dorsal root
Dorsal horn
IVF region
Spinal nerve
Ventral root
Anterior horn
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Other Direct Mechanical Effects to Nerves

• Sympathetic nerves and ganglia can be directly
  impinged by osteophytes extending from the spine.
  As rigid extensions from the vertebrae, a claw
  spur reaching the vicinity of the sympathetic
  chain perturbs it as motion occurs.
• Triano, in Haldeman, Principles and Practice of
  Chiropractic 1992, p.254

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Dorsal root
DRG
Spinal Nerve
Ventral root
Sympathetic Chain Ganglion
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Cervical Spine Neuroanatomy
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There is evidence of nerve compression at the
level of the IVF occurring anywhere from 15.4 to
78 of levels inspected.
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Pressures as little as 10 mm Hg can alter the
nerve root and dorsal root ganglions ability to
function normally. In the normal range of motion
the pressures generated in the IVF may exceed 30
mm Hg.
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The concept that a vertebral subluxation can
produce pressure increases at the level of the
IVF is supported by the literature. This
increase, however mild, is enough to alter nerve
function.
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The garden hose theory or hard bone - soft nerve
explanation of vertebral subluxation is
considered by some to be archaic but appears to
be a valid entity at least in the lower cervical
spine.