Motor System Pain Flashcards
What is the vicious cycle theory of pain and motor control?
- muscle activity => increases in pain => ischaemia + accumulation of pain-producing agents
What is another name for the viscous cycle theory
- pain-spasm-pain cycle
What are the steps involved in the vicious cycle theory?
- pain stress
- muscle tension
- decrease in circulation
- increase in pain
- even more tension
- even less circulation
- more pain
- muscle tension etc.
What are the limitation of the vicious cycle theory?
- overly simplistic
- doesn’t explain increase and decrease of tone in same muscles/groups
- myalgia (muscle pain) generally has no increase in algesic (pain-producing substances)
What is the pain adaptation theory?
- activity of painful muscles reduces during voluntary efforts (hypotonic)
- antagonist muscles increase voluntary efforts (hypertonic)
What effects pain-related inhibition?
- Hilton’s law
- joint effusion
What is Hilton’s law?
- nerves that supply the joint, supply muscles that control the joint
What happens when a joint has effusion?
- neuromuscular inhibition + altered joint mechanics
What happens if the knee joint has effusion?
- neuromuscular inhibition of quads => reduced tone (hypotonic)
- hamstrings increased activity => increased tone (hypertonic)
What happens to LBP and motor control in the TVA?
- LBP => deficit in motor control of TVA <= due to increased cortical inhibition
- LBP => TVA unable to increase in cross sectional size when in pain
- reduction in pain -> TVA fires again
- need to remove pain first before strengthening TVA
What happens to muscles and proprioception during pain adaptative theory
- strain of small joints/muscles
- local protective ‘spasm’
- alters proprioception
- deep stabilising muscles become hypertonic, weak and flaccid
- superficial muscles become hyperactive, hypertonic and guarded
- leads to ischaemic pain
What is Torticollis?
- head side bends + rotates => shortening neck
Which muscles of the next are important for strength and proprioceptive movement?
- deep flexors => longus colli + longus capitus
What happens when longus colli becomes hypotonic?
- neck pain
What is the craniocervical flexion test?
- pt lines supine
- chin + forehead level
- uninflected pressure cuff under neck => inflate to 20mmHg
- PT nods to increase pressure by 2mmHg, holds for 5 sec
- repeat up to 30mmHg in 2mmHg increments
- observe/palpate use of superficial flexors => should be able to nod without using SCM, scalenes, traps
- good for primary HAs
What is the relationship between neck pain and migraines?
- neck pain > with > frequency of HAs
- chronic migraine => tension type HAs
- increased activity of neck muscles during exercise and mental tasks
- hypertrophy of rectus capitus posterior minor
- migraineuse have altered motor control + greater Co activation of flexors
When you have an injury, patients often describe feeling stiff, describe how this mechanism comes about and how it can be helpful
- pain injury (Nociception) or threat
- activity in muscles
- changes in levels of nervous system
- change in behaviour in area
- increase in stiffness (less prone to injury)
- short term benefit, however, long term consequences e.g. increases load, reduces movement and variability
What is the difference between perceived stiffness and actual stiffness?
- LBP patients do not have increase tone of ES muscles
- LBP patients have increased perception of back muscles feeling stiff
- LBP patients over estimate pressure on spinal muscles + detect change better
- manipulation (creaking/grinding) increases perception of stiffness
Describe the pathway of cortical pain-related inhibition
- descending cortical inhibition reduces ability of muscle to fire
- results in reduced muscle strength + motor control => insufficient capacity + control of muscle to perform task => pain + reduced performance
OR
- sufficient muscle strength but not enough control to perform task => pain + reduced performance or vice versa
- have to have strength + control to perform task
What is the problem with rehabilitation and cortical pain-related inhibition?
- most rehab focuses on improving strength but not descending motor control for cortical inhibition
How do you overcome descending motor cortical inhibition?
- external cues rather than counting e.g. metronome
What is loss of demarcation in the sensory homunculus
- smudging occurs between cortical zones of the brain and the hand becomes less clear where it starts and ends
Where else can smudging happen?
- motor cortex in patients with recurrent low back pain
What happens in the cortex (sensory + motor) when playing sport?
- visual cortex identifies object, size, direction, velocity
- Pre motor cortex develops motor program that will allow approaching the ball and hitting back
- motor cortex sends signals to spinal cord to activate and inhibit arm+ leg muscles
- cerebellum fine tunes movements => proprioceptive information from peripheral sensory receptor
