An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.
Allodynia
Pain due to a stimulus that does not normally provoke pain.
Anaesthesia
Loss of bodily sensation with or without loss of consciousness.
Anaesthesia dolorosa
Pain in an area or region which is anesthetic.
Analgesia
Absence of pain in response to stimulation which would normally be painful.
Causalgia
A syndrome of sustained burning pain, allodynia, and hyperpathia after a traumatic nerve lesion, often combined with vasomotor and sudomotor dysfunction and later trophic changes.
Central pain
Pain initiated or caused by a primary lesion or dysfunction in the central nervous system.
Dysaesthesia
An unpleasant abnormal sensation, whether spontaneous or evoked. Special cases of dysesthesia include hyperalgesia and allodynia.
Hyperaesthesia
Increased sensitivity to stimulation, excluding the special senses.
Hyperalgesia
Increased pain from a stimulus that normally provokes pain.
Hyperpathia
A painful syndrome characterized by an abnormally painful reaction to a stimulus, especially a repetitive stimulus, as well as an increased threshold. It may occur with allodynia, hyperesthesia, hyperalgesia, or dysesthesia.
Hypoalgesia
Diminished pain in response to a normally painful stimulus.
Neuralgia
Pain in the distribution of a nerve or nerves.
Neuritis
Inflammation of a nerve or nerves.
Neuropathic pain
Pain caused by a lesion or disease of the somatosensory nervous system. It is a clinical description and not a diagnosis. Subsets are:
Central neuropathic pain - caused by a lesion or disease of the central somatosensory nervous system
Peripheral neuropathic pain - caused by a lesion or disease of the peripheral somatosensory nervous system
Neuropathy
A disturbance of function or pathological change in a nerve: in one nerve, mononeuropathy; in several nerves, mononeuropathy multiplex; if diffuse and bilateral, polyneuropathy.
Nociception
The neural process of encoding noxious stimuli.
Nociceptive pain
Pain that arises from actual or threatened damage to non-neural tissue and is due to the activation of nociceptors.
Nociceptive stimulus
An actually or potentially tissue-damaging event transduced and encoded by nociceptors.
Nociceptor
A high-threshold sensory receptor of the peripheral somatosensory nervous system that is capable of transducing and encoding noxious stimuli.
Noxious stimulus
A stimulus that is damaging or threatens damage to normal tissues.
Pain threshold
The minimum intensity of a stimulus that is perceived as painful. The threshold is really the experience of the patient, whereas the intensity measured is an external event. The stimulus is not pain and cannot be a measure of pain.
Pain tolerance level
The maximum intensity of a pain-producing stimulus that a subject is willing to accept in a given situation. As with pain threshold, the pain tolerance level is the subjective experience of the individual.
Paraesthesia
An abnormal sensation, whether spontaneous or evoked. Compare with dysesthesia. Paresthesia is used to describe an abnormal sensation that is not unpleasant while dysesthesia be used preferentially for an abnormal sensation that is considered to be unpleasant.
Sensitisation
Increased responsiveness of nociceptive neurons to their normal input, and/or recruitment of a response to normally subthreshold inputs. Sensitization can include a drop in threshold and an increase in suprathreshold response. Spontaneous discharges and increases in receptive field size may also occur. It can be:
Central sensitisation - increased responsiveness of nociceptive neurons in the central nervous system to their normal or subthreshold afferent input
Peripheral - increased responsiveness and reduced threshold of nociceptive neurons in the periphery to the stimulation of their receptive fields