Definitions
☛ Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Pain is always subjective. (International Association for the Study of Pain).
☛ Pain is what the patient says hurts. It is what the patient describes and not what others think it ought to be.
Acute and chronic pain
Acute pain
☛ is usually due to a definable acute injury or illness
☛ it has a definite onset and its duration is limited and predictable
☛ it is accompanied by anxiety and clinical signs of sympathetic over activity
☛ treatment is directed at the acute illness or injury causing pain, with or without the short term use of analgesics
Chronic pain
☛ results from a chronic pathological process
☛ it has a gradual or ill-defined onset, continues unabated and may become progressively more severe
☛ is said to exist if the pain persists longer than the expected healing time for the injury or illness in question
☛ the patient appears depressed and withdrawn
☛ there may be no sympathetic over-activity and patients are frequently labelled as "not looking like somebody in pain"
☛ requires treatment of the underlying disease where possible, regular use of analgesics to relieve pain and prevent recurrence, as well as psychosocial supportive care
Incident pain
☛ occurs only in certain circumstances, such as after a particular movement or on standing
☛ should be regarded as chronic pain but, as it is intermittent, it is better managed with local measures where possible
Breakthrough pain
☛ is a transitory exacerbation of pain that occurs on a background of otherwise stable and controlled pain
Nociceptive, neuropathic and psychogenic pain
Nociceptive pain
☛ nociceptive or physiological pain is produced by stimulation of specific sensory receptors or nociceptors in the tissues
☛ the neural pathways involved are normal and intact
☛ somatic pain from the skin and superficial structures is usually well localized
☛ visceral pain is less well localized and there is often referred pain to cutaneous sites
Neuropathic pain
☛ is caused by peripheral or central nervous system injury
☛ pain occurs because the injured nerves react abnormally to stimuli or discharge spontaneously
☛ neuropathic pain is described as
↳ a burning stinging feeling (dysaesthesia)
↳ a shooting pain like an electric shock (lancinating)
↳ an aching sensation often relieved by firmly squeezing or gripping the affected area
☛ is less responsive to non-opioid and opioid analgesics and may respond better to an adjuvant analgesic
Sympathetic pain
☛ is caused by damage to sympathetic nerves
☛ is characterized by burning pain and increased sensitivity
☛ there are signs of sympathetic dysfunction in the affected area
↳ vasomotor instability (erythema, pallor, oedema)
↳ sudomotor (sweating) abnormalities
↳ trophic changes (thinning of the skin and atrophy of the subcutaneous tissue)
☛ is less sensitive to non-opioid and opioid analgesics
☛ often responds well to a regional sympathetic nerve block
Psychogenic pain
☛ is pain for which there is no physical basis in a patient who has other evidence of psychopathology
☛ in palliative care, patients are occasionally seen with psychosocial or existential distress in whom psychological factors and not the medical condition are judged to play the major role in the onset and maintenance of the pain, and for whom primarily psychological therapies may be appropriate
☛ however, all chronic physical pain is associated with some degree of psychological distress, for which the treatment should be primarily directed at the cause of the physical pain
Determination of the type of pain is an important part of assessment, as different types of pain may respond better to different treatments
see Principles of Treatment
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Source:
The IAHPC Manual of Palliative Care 3rd Edition
https://web.archive.org/web/20210122105526/https://hospicecare.com/uploads/2013/9/The%20IAHPC%20Manual%20of%20Palliative%20Care%203e.pdf
