Cardio

11/15/99

 

Obstructive Diseases

Asthma

Alterations of spinal excitability

• Habituation
• Progressive decrease in response to a constant, repeated stimulus
• Results from interneuronal inhibition primarily form musculoskeletal afferentation—like DTR and muscle tone
• Normal response that healthy people develop
• It is needed for survival
• Does not occur in peripheral inflammation; for example tendonitis (muscle increases in tone)
• Inflammation causes many neurotransmitters to be released
• Sensitization
• The opposite of habituation
• Progressive increase in response to a repeated stimulation
• Occurs w/activation of more receptors, primarily nociceptors
• Spinal interneurons become excitable
• Increased protein synthesis w/in the neurons may sustain the sensitization for weeks
• For example, strong perfume causes coughing and headaches
• Your rxn becomes stronger each time you are exposed to the stimulus
• Free nerve endings are involved
• Fixation
• Basis for the "facilitated segment" as described by Korr
• Often results from peripheral inflammation—What causes the inflammation?
• Increasing synaptic contacts, inhibition of inhibitory interneurons, and afferentation from non-nociceptive neurons contribute to this phenomenon—Barry Wyke w/mechanoreceptors—does not necessarily cause pain
• Spinal alteration
• Reduce afferent input is the goal of treatment
• Free motion of the joints and relieving soft tissue tensions
• Sympathetic efferent discharge (release NE) is thought to sensitize afferent nerve endings—sympatheticotonia

 

Trauma or Irritant

• Leads to afferentation
• Sensitization
• Sympatheticotonia
• ­ NE expression
• Mast cell activity/inflammation
• Predinisone is given to attack inflammation
• Function/CES
• Once the process starts it keeps cycling

 

Trauma or irritant®afferentation®sympatheticotonia® ­NE expression

­                                                                      ¯

Function/CES ¬mast cell activity/inflammation

 

	Extrinsic	Intrinsic
Etiology	Mainly atopy	Complex
Antigen related	Yes	No
IgE-mediated	Yes	No
Eczema, hay fever	Common	Uncommon
Family Hx	Usually positive	Often negative
Hypersensitivity skin test	Often positive	Usually negative
Typical attack	Acute, mild	Often severe
Results of treatment	Effective	Variable
Environmental control	Useful	Not useful
Desensitization	Occasionally helpful	Not helpful
Relief b/w attacks	Complete	Often incomplete
Prognosis	Usually good	Less avoidable

 

• Intrinsic is quickly becoming classified as Neurogenic
• Vagus nerve innervates the smooth muscle of the airway
• Vagus is motor and sensory—carries both types of actions
• Vagal afferent nerve goes w/the irritant receptors
• Irritant reflex