WHAT IS PAIN?

WHAT IS PAIN?

  1. 1
    WHAT IS THE MEANING OF PAIN?
    • Pain is a subjective, unpleasant, sensory, and emotional experience associated with actual or potential tissue damage or abnormal functioning of nerves. It may be classified as acute, chronic, or cancer pain.
  2. 2
    WHAT IS TH EPHYSILOGY OF PAIN?

    ADAPTIVE (PHYSIOLOGIC) PAIN

    • Nociceptive (e.g., from touching something too hot, too cold, or sharp) and inflammatory pain (e.g., trauma or surgery) are both adaptive and protective.
    • The steps in processing pain are
      • Transduction—stimulation of nociceptors.
        • Nociceptors found in both somatic and visceral structures are activated by mechanical, thermal, and chemical stimuli. Noxious stimuli may cause the release of cytokines and chemokines that sensitise and/or activate nociceptors.
      • Conduction—Receptor activation leads to action potentials that continue along afferent fibres to the spinal cord. Stimulation of large-diameter, sparsely myelinated fibres evokes sharp, well-localised pain. Stimulation of small-diameter, unmyelinated fibres produces aching, poorly localised pain.
      • Transmission—Afferent nociceptive fibres synapse in the spinal cord’s dorsal horn, releasing excitatory neurotransmitters, e.g., glutamate and substance P). The spinothalamic tract and other pathways bring the signal to the brain’s higher cortical structures.
      • Perception—The experience of pain occurs when signals reach higher cortical structures. Relaxation, meditation, and distraction can lessen pain, and anxiety and depression can worsen the pain.
      • Modulation—Possible modulating factors include glutamate, substance P, endogenous opioids, γ-aminobutyric acid (GABA), norepinephrine, and serotonin.
    • The interface between neurons and immune cells in the central nervous system (CNS) may facilitate the maintenance of chronic pain.

    MALADAPTIVE (PATHOPHYSIOLOGIC) PAIN

    • Pathophysiologic pain (e.g., postherpetic neuralgia, diabetic neuropathy, fibromyalgia, irritable bowel syndrome, and chronic headaches) is often described as chronic pain. It results from damage or abnormal functioning of nerves in the CNS or peripheral nervous system (PNS). Pain circuits sometimes rewire themselves anatomically and biochemically, resulting in chronic pain, hyperalgesia, or allodynia.
  3. 3
    WHAT ARE THE SIGNS AND SYMPTOMS OF PAIN?

    GENERAL

    • Patients may be in acute distress or display no noticeable suffering.

    SYMPTOMS

    • Acute pain can be sharp or dull, burning, shock-like, tingling, shooting, radiating, fluctuating in intensity, varying in location, and occurring in a temporal relationship with an obvious noxious stimulus. Chronic pain can present similarly and often occurs without a temporal relationship to a noxious stimulus. Over time, the chronic pain presentation may change (e.g., sharp to dull).

    SIGNS

    • Acute pain can cause hypertension, tachycardia, diaphoresis, mydriasis, and pallor. These signs are seldom present in chronic pain. In chronic noncancer pain, depression, sleep disturbances, anxiety, and employment and family instability tend to dominate.
    • In acute pain, outcomes of treatment are generally predictable. In chronic pain, comorbid conditions are often present, and treatment outcomes are often unpredictable. For chronic noncancer pain, an interdisciplinary approach (e.g., pain clinic) is preferred.
KNOWLEDGE BASE
About Genomic Medicine UK

Genomic Medicine UK is the home of comprehensive genomic testing in London. Our consultant medical doctors work tirelessly to provide the highest standards of medical laboratory testing for personalised medical treatments, genomic risk assessments for common diseases and genomic risk assessment for cancers at an affordable cost for everybody. We use state-of-the-art modern technologies of next-generation sequencing and DNA chip microarray to provide all of our patients and partner doctors with a reliable, evidence-based, thorough and valuable medical service.

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