Chronic pain

Pain

An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.

Nociception

The neural process of encoding noxious stimuli.

Nociceptive Pain

Pain that arises from actual or threatened damage to non-neural tissue due to the activation of nociceptors.

Neuropathic Pain

Pain caused by a lesion or disease of the somatosensory nervous system.

Nociplastic Pain

Pain that arises from altered nociception despite no clear evidence of actual or threatened tissue damage or somatosensory lesion.

Transduction

The neural process by which noxious physical stimuli are converted into electrical impulses at sensory nerve endings.

Peripheral Sensitization

Increased responsiveness and reduced threshold of nociceptive neurons in the peripheral nervous system.

Central Sensitization

Increased responsiveness of nociceptive neurons in the central nervous system to normal or subthreshold afferent inputs.

Primary Hyperalgesia

Increased pain sensitivity occurring directly at the primary site of tissue injury.

Secondary Hyperalgesia

Increased pain sensitivity occurring in uninjured tissues surrounding the primary site of injury.

Neurogenic Inflammation

Inflammation triggered in peripheral tissues by the antidromic release of neuropeptides like Substance P and CGRP from sensory axons.

Wind-up

A progressive increase in dorsal horn neuronal activity caused by high-frequency or repetitive stimulation of C-fiber nociceptors.

NMDA Receptors

Glutamate receptors in the dorsal horn that open upon high-frequency stimulation to allow calcium influx and promote central sensitization.

Allodynia

Pain produced by a stimulus that does not normally provoke pain.

Hyperalgesia

An increased or exaggerated pain response to a stimulus that normally provokes pain.

Chronic Pain

Pain that persists or recurs for longer than three months.

Chronic Primary Pain

Chronic pain in one or more anatomical regions characterized by significant emotional distress or functional disability without a clear secondary cause.

Gabapentinoids

bind to the alpha-2-delta subunit of voltage-gated calcium channels to decrease central sensitization.

Tricyclic Antidepressants

work by inhibiting monoamine reuptake and blocking sodium channels.

Serotonin-Noradrenaline Reuptake Inhibitors

enhance descending pain inhibition by selectively blocking serotonin and noradrenaline reuptake.