What is the pain spasm model (vicious cycle theory)?
Excitatory - Injury to the muscle leads to increased muscle spasm in the area of injury - because of an increase in metabolites = increase pain pain results in an increased activity which in return will lead to an accumulation of metabolites and consequently further increase pain. the muscles in the surrounding structures would decrease motion to prevent injury
What are the two physiological theories for the pain spasm model?
- nociceptive afferent information is travelling via the spinal cord to both higher nervous centres for pain perception and to alpha motor neurons on segmental level causing an increase in muscle activation - nociceptive information travels to gamma motoneurons, affecting increased muscle spindle output and thereby resulting in hyperexcitability of the alpha motoneuron
What is the pain adaptation model?
Inhibitory - Increase activity in antagonist mm. to inhibit movement of injured muscle = reduce pain the pain will decrease activity in muscles acting as an agonist and increase activity in muscles acting as an antagonist, thereby being adaptive to the function of each m
What is the pathophysiology of the pain adaptation model
nociceptive information transferred either via inhibitory or excitatory interneurons to the alpha motoneuron p
What is Hodges motor adaptation to pain model?
- change in mechanical behaviour - redistribution of mm. load (1) aims to protect from further pain or injury, (2) involves redistributions of activity within and between muscles (3) leads to changes in mechanical behaviour (4) involves changes at multiple levels of the motor system, which may be complementary, additive or competitive, (5) with short-term benefits, but potential long-term consequence
What is the gate control theory
-Cells in substancia gelatinosa act as a gate for pain. It control impulses via A-delta and C fibres coming into the brain by closing the gate, which in turn blocks the signals and decreases pain. According to this theory, nociceptive impulses are transmitted to the spinal cord through large A- delta and small C- fibre types These fibres create synapses with neurons in the SG The cells in this structure function as a gate, regulating transmission of impulses to CNS Stimulation of larger nerve fibres (A-alpha, A-beta) causes the cells in substantia gelatinosa to "close the gate„ for transport of painful information centrally. AclosedgateleadstodecreasesstimulationofT-cells(the 2nd afferent neuron), which decreases transmission of impulses, and diminishes pain perception
Where modulation of nociceptive information occur?
PAG, the rostral ventromedial medulla (RVM), and the pontine tegmentum
WHere does fear get processed in the brain
Amygdala which projects to prefrontal cortex
What information is processed by the anterior cingulate cortex?
escape and avoidance of noxious stimuli.
WHat do off cells and on cells do?
OFF cells are thought to be involved in descending inhibition, whereas ON cells are thought to be involved in descending facilitation of nociceptive information
What are the 4 current theories?
1. Suboptimal movement/motor control as a precursor to injury and pain
2. Impaired movement/motor control as a consequence of interference by actual or threatened injury and/or pain
3. Modification of movement/motor control for protection of the painful/injured/threatened region
4. Modified movement/motor control explained by a conditioned association with pain
What do the 4 current theories propose together?
changes motor function, such as subtle redistribution of activity within or between muscles, to complete avoidance of movement, activity, or participation
What is the condition response hypothesis
Association of pain with movement
change behaviour to the new unconditioned stimulus of protective behaviour
What is peripheral neuropathic pain?
neuropathic pain is a direct consequence of a lesion or disease affecting the peripheral somatosensory system.
What is central neuropathic pain?
Central neuropathic pain is a direct consequence of a lesion or disease affecting the central somatosensory system
What is a mononeuropathy?
A disorder of a single nerve or nerve trunk.
What causes neuropathies?
entrapment, compression, stretch injury, ischemia, infection, or inflammation of a nerve.
What is polyneuropathy?
generalised, relatively homogeneous process affecting many peripheral nerves, with the distal nerves usually affected most prominently
WHat causes palyneuropathies?