Nociceptive – normal response to harmful stimuli or injury. Example – joint pain or referred pain from an organ
Neuropathic – caused by a lesion or disease in the somatosensory nervous system. Perceived as numbness, hypersensitivity, and paresthesia. Example – (not limited to) – diabetic neuropathy, spinal cord injury, phantom limb
Inflammatory – a result of activation and sensitization of nociceptive pain by mediators released at a site of tissue inflammation. Example – appendicitis, RA, IBD, and herpes zoster
Physiology of Pain
1. Pain stimulates pain receptors which then signal to your spinal cord and then to your brain. Once the pain is processed in the brain, it sends an impulse down to the spinal cord and to the appropriate nerves which command the body to react thereby withdrawing from the stimuli
a) Pain receptors are present everywhere in the body and have three different types.
Mechanical for high pressure or stretching, motion/movement
Thermal for extreme heat and cold
Chemical from chemicals that are released due to trauma, inflammation, or other painful stimuli. Examples of these chemical substances include bradykinin, serotonin potassium ions, and acids like lactic acid.
Prostaglandins increase the sensitivity of pain receptors. NSAIDs/Tylenol decrease the effect of prostaglandins which is how they work as painkillers.
b) Nerve fibers
Fast – like pricking yourself with a needle or touching a burning object. Transmitted through thick nerve fibers. the pain is localized
Slow – starts immediately after fast pain. Transmitted through slow nerve fibers called C-fibers. Can be the primary type of pain originating in the internal organs. The pain is diffused.
Pain is a multidimensional phenomenon. It grabs your attention and produces strong emotional reactions that adversely affect a patient’s function, quality of life, emotional state, social and vocational status, and general well-being.
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