Y2, Y2Notes, Y2 NSB, Neuro Notes, Neuroscience, Christopher Yeo, Chris Yeo,   NSBNeuro , 

• Pain: an unpleasant emotional and sensory experience associated with or resembling
that associated with actual or potential tissue damage
• Nociception: the neural process of encoding and processing noxious stimuli
• pain is highly individual and subjective
• pain and injury have a strong relationship
Nociceptors:
• fast pain- myelinated A delta fibres
• slow pain- non-myelinated C fibres
o in the skin and deep tissue, nociceptors sensitise following tissue injury and
become more sensitive to many stimuli.
nerve growth factor and TRPV1 play a role in this process
o travels to the dorsal horn of the spinal cord
• injury-related information projects to the brainstem and the thalamus (a bit) as the
information is used for escape, attack (behavioural changes to survive and to heal)
• Chronic Pain is pain experienced over 3 months:
o Chronic Primary Pain- don’t know what causes the pain (e.g. fibromyalgia)
(few treatment options as no know mechanism)
o Chronic Secondary Pain- pain that originates due to another disease (treatment
options)
o Peripheral nervous system pain- inflammatory pain caused by tissue damage
(NSAIDS)
o Central nervous system pain- neuropathic pain initiated or caused by a primary
lesion or disease in the PNS or CNS (gabapentin, tricyclic antidepressants,
opiates)
• Opioids:
o prescribing opioids leads to addiction (tolerance, hypersensitivity, addiction)

in chronic pain, pain still persists even after the injury has healed because of long-
lasting plastic changes in the spinal cord that have not reversed

o try to inhibit the flow of injury information to the brain:
the dorsal horn expresses NK1R (Substance P receptor)
looks like substance P, but it is actually saporin which binds and kills
the nerve to stop the pain.
use botulinum as well, which silences the neurone rather than
killing it. (dermorphin-botulinum analgesia lasts for months)