Clinical management of
neuropathic pain
K W Chan
陳國維
Dear Editor,
I refer to the article
"Clinical management of neuropathic pain" by Dr K F Chin published
in your Journal Vol 23 Oct 2001 and would like to congratulate Dr Chin
in writing such a good synopsis. I want to highlight a few points for
discussion.
- While most of the acute pain has a noxious stimulus
(a stimulus that is capable of producing tissue damage), the relation
between psychogenic pain and the noxious stimulus is less well defined.
A patient in fear of having cancer of the brain may experience pain
(headache). With chronic pain, such as chronic low back pain, patients
may experience persistent back pain long after the noxious stimulus
has disappeared. In fact, the approach towards chronic pain management
nowadays builds from the Biopsychosocial pain model, where the patient's
pain is taken as the unpleasant sensory and emotional experience from
interactions among the patient's physical, psychological and social
domains. This gives family physicians an important role in the management
of patients with chronic pain.
- The biological response to a noxious stimulus
is NOT pain. The biological sensory/discriminative awareness
of noxious stimuli is called NOCICEPTION.
- In order to accommodate the psychogenic causes
of pain into Dr Chin's definition, the International Association of
the Study of Pain (IASP) expands the definition of pain as:
"An unpleasant sensory and emotional experience associated with
actual or potential tissue damage, or described in terms of such damage".
Notice that this definition
describes pain in three different aspects. The first refers to the physical
component (sensory), whereby tissue damage generates sufficient excitation
of the special nerve endings in the peripheral nervous system and sends
off nerve impulses to the spinal cord or brain stem and thence on the
brain i.e. the nociception. The second refers to the psychosocial component
(emotional), which centers on the emotional experience of the nociceptive
impulses on the body'scognitive and behavioural responses. The third
aspect refers to the cause of this nociceptive and emotional experience,
which can be "actual", "potential" or even "perceived"
as described tissue damages.
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K W Chan, MMedPhyMed(Musculoskeletal)
USyd
Family Physician in Private Practice.
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