Brown sequard syndrome - good clinical example of
syringomyelia
brainstem stroke
Pain as a clinical entity
can have acute pain
ha ta postop trauma etc
or chronic pain degenerative disease,
and also leads to reduced activities and obesity slash depression.
depressioin can lead to chronic pain
Definitions
Nociception indicator od potntial tissue damage
Pain subjective and depend on individual
it is an affective sensation that is conditional and indispensable (we absolutely need it) it also spreads out in the brain to wake up a numebr of centres
Function of pain
to prevent injury
boy had no c fibres and suffered for it
subjectivity
pain sensitivity vs this is consistent between individuals
pain tolerance
this is what is bearable or tolerable highly variable between individuals
Nociceptors
mechanical, thermnal, polymodal
able to be excited or sensitised like if K+ is released this sensitised them as k+ is released with cell death a lot are silent until sensitised
types of pain fibres
small and fast this is sharp localised first pain
neo spinothalamic it is to alert
vs small and slow this is poly modal/ chemical plaeospinothalamus and is to remind oyu
Primary afferent neurons
nociceptor enters dorsal hord and has lots of modulation there are relfex connections and interneurons
and then ascending fibres through anterolateral pathway to thalamus and cortex
substantia gelatinosa
distribution of pain in. brainstem
somatosensory cortex - awareness limbic system - emotional component diffusely in cerebrum and brainsem - arousal hypothalamus - nausea
An approach to understand pain
nociceptive pain - just normal functioning neuropathic pain - from nerves etc (sticking nerve together and hope it regrows) central pain - thalamic lesion
chronic pain - could be somatisation etc
alleviators and aggrivators
aggrevators
- nociceptor senitisation
- peptide release eg make lesion clean and low damage
- spinal cord wind up (lots of pain all the time makes it more sensitive)
- reduce ongoing stimulus
- muscle spasm - dislocated shoulder they might tense up neck or constant guayding
gate control
activation of large diameter fibres (touch fibres) blocks small fibres
the touch activates inhibitors of pain pathway
we have a descending inhibitors of pain pathway
when we feel pain we inhibit it pretty immediatly
the inhibitory pathways has inhibitors which we activate the inhibitors for. opitates do this
referred and phantom pain