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1
Module 5 Subluxation Theories
Highlights from Section III, chapters 8-18, ofThe Chiropractic Theories: A Textbook of Scientific Research, 4th Edition, Leach 2004
[there is a copy in the reference books on the top floor of the library]
Biomechanics (TECH 71613)
James W. DeVocht, DC, PhD
2
The Cardinal Signs of Inflammation(classic clinical signs)
from Leach pages 131, 132
Rubor - redness
Tumor - swelling
Calor – heat, fever
Dolor - pain
Functio Laesa – loss of function
Chapter 8: Inflammation Hypothesis
3
Inflammatory Process is not all bad
from Leach page 132
Maintenance of tissues
Allows for remodeling
4
Two Distinct Forms of Inflammation
from Leach page 131
Acute – 3 phases 1. Vasodilation 2. Slowing of blood flow 3. Migration of white blood cells
(can be self sustaining)
Chronic - Accumulation of lymphocytes & macrophages - Angiogenesis - Connective tissue proliferation
5
Chiropractic Management of Inflammation(according to Lantz, Chapter 8 in Leach)
from Leach page 136
Ice
Nutrition
Exercise Strategies
6
Segmental dysfunction: the most common spinal lesion recognized by lessened or otherwise altered mobility, altered pressure threshold to pain, and signs of neuromuscular dysfunction.
from Leach pages 137, 138
Chapter 9: Segmental Dysfunction Hypothesis: Joint and Muscle Pathology and Facilitation
7
from Leach page 138
Segmental facilitation: a lowered threshold for firing a neuron in the spinal cord as a result of afferent bombardment associated with spinal lesions.
8adapted from Leach Fig 9-1
Neurobiology of Muscle Spindles
Gamma efferent fibers
Group Ia afferent fiber
Group II afferent fiber
Intrafusal muscle fibersCapsule
10
Leach Fig 9-4
Discharge of an Afferent Nerve in Response to Movement of the L5-L6 Facet Joint in a Cat
11
Hypothesized Effects of Entrapped Joint Meniscoid (Jones 1989)
from Leach page 149
Increased joint capsule tension Increased mechanoreceptor activity Increased nociception Decreased pain threshold & hypertonic paraspinal musculature (classic signs of segmental dysfunction)
Joint hypomobility Capsular adhesions Obliteration of joint cavity (no movement at all)
The decreasing joint mobility Loss of bone minerals Premature degeneration
12
Extensive Investigations of Lumbar Zygapophyseal Joints
(Giles 1987,1989)
from Leach page 148
Conclusion: Chiropractic benefit could be due to releasing trapped intra-articular synovial folds and stretching the joint capsule
14
The Korr Model of Segmental Dysfunction
Leach Fig 9-10
A. CNS orders skeletal muscle contraction
B. At same time, external forces push segments closer together than expected
C. CNS turns up gain for motor neuron based on input from spindles
D. Body recoils but muscles now resist
E. Muscle is stretched at normal length(CNS in confused by bad info from spindles)
(seems consistent with EMG data)
15
Patterson-Steinmetz Model of SDF (1986)
Leach Fig 9-11
Cerebral lesion rear leg flexion
Cord was then severed
- if done immediately, no flexion
- if > 45 min, full flexion remained
- if < 35 min, some flexion remained
Spinal learning occurs if lesion is sustained over time
16
Mense Model (1991)
Leach Fig 9-14
Mechanical spinal lesion, spasm local ischemia edema release of vasoneuroactive substances reinforces the spasm (self propagating)
As a result of the local ischemia decreased ATP failure of Ca++ pump increased muscle contracture (spasm) more ischemia
There must be some sortof self-reinforcing cycle
17
Instability hypothesis: Severe or repeated trauma and postural stresses can cause tissue damage and resultant instability and/or misalignment. This can predispose the spine to painful episodes and ultimately lead to premature stabilization of the involved motion segments.
from Leach page 207
Chapter 10: Instability Hypothesis
18
Postural Deviations
Leach Fig 10-2
A & B: Reversed cervical curvature
C: Significant DJD at C3-C4 level
D: Spondylolisthesis of L5
19
4 Methods of Quantifying Cervical Lordosis
Leach Fig 10-3
1. Curve depth
2. C2-C7 angle
3. Chord-C7 angle
4. Radii of curvature
20
Leach Fig 12-1
Chapter 12: Neuropathology Hypothesis
Mechanical susceptibility of nerve root to distortion - compression - stretch
Biological susceptibility of nerve root to distortion - inflammation - edema - venous obstruction of IVF
21Leach Fig 12-2
Susceptibility ofcat nerves to compression block
Dorsal roots much more susceptible than peripheral nerves
22
Leach Fig 12-3
Structural Effects of Nerve Compression (MacGregor 1975)
Displaced fluid resulting from blockage forces radial distention and lengthening
23
Hypothesis: spinal joint lesions may trigger facilitation-induced reflexes that impair or disturb visceral function
from Leach pages 269-271
Chapter 13: Somatoautonomic Reflex Hypothesis
A. Central modulation: disturbance of lateral fibers of the spinothalamic system and/or medial fibers of the dorsal column system
B. Peripheral modulation: segmental facilitation from prolonged bombardment of the dorsal horn to cause habituation of certain spinal reflex arcs. This could result from failure of damaged skeletal tissues to heal promptly.
24
Sympathicotonia – hyperactive sympathetic function associated
with segmental dysfunction (SDF) Leach page 274
25
from Leach pages 277-282
Purported Chiropractic Success with Somatoautonomic Dysfunction
Bell PalsyDown SyndromeDysphagiaMigraine headachesMyoclonusNystagmusSeizure disordersSpasmodic dysphoniaVertigo (cervicogenic)
27
adapted from Leach Fig 13-4
Proposed Mechanism for PNS Mediation of Plasma Extravasation
(major feature of acute inflammation)
- Substance P (SP) released from primary afferent fibers
- Acts on mast cells to initiate release of prostaglandin (PG)which causes plasma extravasation
- Adjustments are thought to affect plasma levels of SP
28
Hypothesis: Intervertebral subluxation may, in some severe cases (and even in the absence of fracture-dislocation), irritate, compress, or destroy portion of the spinal cord.
from Leach page 311
Chapter 14: Myelopathy Hypothesis
32
Chapter 15: Hypothesis of Vertebrobasilar Insufficiency
Hypothesis: cervical joint lesions may compromise the vertebral arteries, especially in the presence of anomalies within the vertebrobasilar system.
from Leach page 327
33Leach Fig 15-1
Vertebral artery is most susceptible in the upper cervical spine to deflection and obstruction by subluxation, osteophytic spurring, increased tortuosity from lower cervical degenerative joint disease, and even cervical spine manipulation itself.
34
Chapter 16: Neuroimmune Hypothesis
Hypothesis: immune response is significantly affected by neural influence and therefore can be positively affected by chiropractic adjustments.
This theory was developed primarily from D.D. Palmer’s early writing.
from Leach page 359
35
Selye’s General Adaptation Syndrome (GAS)
A general model concerning the effects of stress
1. Alarm reaction (increased secretion of cortisone, ACTH etc.) (misc. signs of damage or shock)
from Leach pages 344 - 345
2. Stage of resistance (body seeks to function normally in spite of the stress) (lasts as long as endocrine & other systems hold up)
3. Diseases of adaptation (develops if the body is unable to maintain normal function while the stress continues)
36
Diseases of Adaptation
Includes a wide variety of diseases – not only things like hypertension and gastrointestinal ulcers but possibly many others including nephrosis, nephritis, rheumatic fever, and some tumors.
from Leach page 345
Exposureto stress
Conditioningfactors
Physiologicadaptationsyndrome
Disease ofadaptation
from Leach Fig 16-3