PHTY209 Lecture Notes - Lecture 18: Motor Neuron, Autonomic Nervous System, Palpation
Types of pain - introduction to neuropathic pain
• Define and differentiate between nociceptive, inflammatory, ischaemic and neuropathic pain,
including peripheral and central neuropathic pain
• Nociceptive
o Peripherally dominant pain mechanisms
o Likely to be more associated with acute injury, with damaged and healing tissues
(inflammatory driven) and postural pain (ischaemic driven)
o It may also be part of the pain mechanisms in weakened and deconditioned tissues
in chronic pain states
o Description by patient
• Consistent in its behaviour (limited to one region and responds predictably)
• The stimulus intensity and sensation are reasonably related
• Some postures and activities consistently ease the pain, while others make
worse (ischaemic driven)
• Rest helps to ease the pain
• Threshold for pain can be lowered: primary hyperalgesia (inflammatory driven)
o Examination findings
• Pain results from stimulation of high threshold afferents so should respond to
mechanical force in consistent way
• Tests that offload the affected tissue can be expected to reduce pain, whereas
increased stretch/pressure should increase pain
• Manual therapy that has effect on mechanical status of tissues should improve
pain
▪ i.e. reduce the load, improve mobility (taping, stretching, etc.)
• Inflammatory driven/inflammatory
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o Cardinal signs of inflammation (redness, swelling, heat)
o Associated with acute pain and tissue damage
o Typically resolves after resolution of initial injury (within weeks)
• Unless part of systemic condition i.e RA where inflammation can remain active
o Well localised area of hyperalgesia (response to noxious stimuli in the area can be
increased/exaggerated, due to reduced threshold/sensitisation of nociceptors)
o Worse in the morning and overnight
o May be hints that the nervous system is unhealthy (entrapment) contributing via
neurogenic inflammation
o Beneficial effects of anti-inflammatories
• Ischaemic driven
o Symptoms after prolonged or unusual postures
o Rapid ease of symptoms after a change in posture
o Symptoms towards end of day/ after accumulation of activity
o Poor response to anti-inflammatory medication
o Sometimes no evidence of actual trauma
• Neuropathic
o Pain caused by a lesion or disease of the somatosensory nervous system
• Lesion = macro or microscopically identifiable damage
• Disease = identifiable disease processes i.e. inflammation, autoimmune
conditions
• Somatosensory
o Pain usually results from activation of nociceptive afferents by actual or potential
tissue-damaging stimuli
o Neuropathic pain can arise from damage to the nerve pathway at any point from the
terminals of the peripheral nociceptor to the cortical neurons in the brain.
o With neuropathic pain – pain may arise by activity generated within the nervous
system without adequate stimulation of its peripheral sensory endings
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Document Summary
Lesion = macro or microscopically identifiable damage: disease = identifiable disease processes i. e. inflammation, autoimmune conditions. Ischaemia: hereditary, cancer, the patient with neuropathic pain, would think if injury to nerve would get decreased sensation: Sympathetic nervous system involvement: expression of new adrenoceptors or adrenoceptors. Sns (autonomic nervous system) activated in stressful situation, associated with fear, stress, excitement (cid:862)fight or flight(cid:863) Signalling in an a fibre (touch) excites an adjacent c fibre: unpleasant sensation from touch = allodynia. Intensity: (vas: quality of pain: burning, lancinating, shooting, cramping, other symptoms: Sensory loss: paraesthesia (abnormal pins and needles, dysaesthesia (unpleasant sensations crawling, hyperalgesia, allodynia, pattern: spontaneous or provoked. Night pain: mechanism: help you to understand the causative event, medication: lack of response to analgesics/anti-inflammatory drugs, other: suggestions of sympathetically maintained pain. Localising the lesion: the neurological examination, testing conduction, test, muscle power/strength of the muscles the nerve/s supply, reflexes subserved by the nerve/s.
