The science and study of pain phenomena. An algologist is a student,
investigator, or practitioner of algology.
Pain due to a stimulus that does not normally provoke pain.
This derived from the Greek "allo" meaning "other" and "odyne," meaning pain.
The original definition adopted by the IASP committee was "pain due to
non-noxious stimulus to the normal skin." The latest definition omits the words
"to normal skin" in order to remove implication that allodynia applies only to
referred pain. The present definition also omits "non-noxious" because a
stimulus may be noxious at some times and not at others, (e.g., intact skin vs.
sunburned skin) and also because the boundary of noxious stimulation may be
hard to delimit. It is best to define allodynia in terms of the response to
clinical stimuli. The normal response to the stimulus can always be tested
elsewhere in the body, usually in a corresponding part. Note that allodynia
involves a change in the quality of a sensation, whether tactile, thermal, or
of any other sort. The original response to a stimulus was not pain, but the
present response is. There is thus a loss of specificity of a sensory modality.
In contrast, hyperalgesia represents an augmented response in a specific mode
such as pain. With other cutaneous modalities, hyperesthesia is the term that
corresponds to hyperalgesia, and as with hyperalgesia, sensory quality is
unaltered. In allodynia the stimulus mode and the response mode differ but not
with hyperalgesia.
Absence of pain in response to stimulation that would normally be painful. In
common parlance, health science professionals often use this term to mean
hypoalgesia, a reduction in the intensity of pain that occurs in response to a
normally painful stimulus. Equating the term analgesia with clinical pain
relief leads to conceptual confusion. One can relieve a patient's pain without
necessarily altering his/her ability to feel a normally painful stimulus.
Absence of all sensory modalities.
Agent/agents that produce regional anesthesia (i.e., in one part of the body)
or general anesthesia (loss of consciousness).
Pain in an area or region that is anesthetic.
Derived from the Latin term "angor" for strangling. Usually employed for pain
syndromes associated with cardiac disease and indicates a feeling of oppression
or tightness of the throat.
Pain in a joint, usually due to arthritis or arthropathy.
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.
Pain associated with a lesion of the central nervous system.
Pain due to loss of sensory input into the central nervous system, as occurs
with avulsion of the brachial plexus or other types of lesions of peripheral
nerves or due to pathology of the central nervous system.
The sensory segmental supply to the skin and subcutaneous tissue.
An unpleasant abnormal sensation, whether spontaneous or evoked. Compare this
term with pain and with paresthesia. Special cases of dysesthesia include
hyperalgesia and allodynia. A dysesthesia should always be unpleasant and a
paresthesia not, although difficulties can emerge when a patient must decide
whether a sensation is pleasant or unpleasant. One should always specify
whether the sensations are spontaneous or evoked.
Increased sensitivity to stimulation, excluding special senses.
An increased response to a stimulus that is normally painful. Please note two
considerations. One is the absence of the word noxious in the definition,
because of difficulties in its use. The second is the inclusion of some
features of allodynia in the definition. Many cases of hyperalgesia have
features of allodynia. The term allodynia pertains when there is not an
increased response to a stimulus that normally provokes pain. However, when
there is also a response of increased pain to a stimulus that normally is
painful, hyperalgesia is the appropriate word. With allodynia the stimulus and
the response are in different modes, whereas with hyperalgesia they are in the
same mode.
A painful syndrome, characterized by increased reaction to a stimulus,
especially a repetitive stimulus, as well as an increased threshold.
Hyperpathia may occur with hyperesthesia, hyperalgesia, or dysesthesia. Faulty
identification and localization of the stimulus, delay, radiating sensation,
and after-sensation may occur. The pain is often explosive in character.
Diminished sensitivity to noxious stimulation.
Diminished sensitivity to stimulation, excluding special senses.
Pain in distribution of nerve or nerves.
Inflammation of a nerve or nerves.
Any pain syndrome in which the predominating mechanism is a site of aberrant somatosensory processing in the peripheral or central nervous system. Some clinical neuroscientists restrict this definition to pain originating in peripheal nerves and nerve roots.
A disturbance of function or pathologic change in a nerve; in one nerve,
mononeuropathy; in several nerves, mononeuropathy multiplex; if symmetrical and
bilateral, polyneuropathy. Although neuritis has been used interchangeably with
neuralgia and neuropathy in the past, it is not reserved for inflammatory
process affecting nerves. Neuropathy does not cover cases like neurapraxia or
neurotmesis.
A receptor preferentially sensitive to a noxious stimulus or to a stimulus that
would become noxious if prolonged. One should avoid use of terms like pain
receptor, pain pathway, etc because they reflect anachronistic concepts and can
mislead. Pain is a complex perception that takes place only at higher levels of
the central nervous system.
A noxious stimulus is one that is potentially or actually damaging to body
tissue. In the true Sherringtonian sense, a noxious stimulus is defined as "one
of intensity and quality which are adequate to trigger a nociceptive reaction
of an animal, including the feeling of pain in humans." In some instances
there is no lasting tissue damage (e.g., muscle pain due to excessive exercise).
An unpleasant sensory or emotional experience which we primarily associate with tissue damage or describe in terms of tissue damage, or both. This is the formal IASP definition.
The least experience of pain that a subject can recognize. Traditionally the
pain threshold is the least stimulus intensity at which a subject perceives
pain in a laboratory experimen t. In psychophysics, a threshold is defined as
the level at which 50% of stimuli are recognized. Thus, the pain threshold is
the level at which 50% of stimuli are recognized as painful. Properly defined,
pain is always the experience of the patient, whereas the stimulus intensity
measured by the psychophysicist is an external event. Psychophysicists
classically define the threshold in terms of the stimulus, and that limits the
usefulness of pain threshold for clinical application. The stimulus is not pain
and cannot be a measure of pain outside the confines of psychophysical modeling.
The greatest level of pain that a subject is prepared to tolerate. Because he
pain tolerance level is the subjective experience of the individual, the same
considerations limit the clinical value of pain tolerance level as pain
threshold.
An abnormal sensation, whether spontaneous or evoked. Compare this term with
dysesthesia. The latter indicates an abnormal sensation that is unpleasant.
Avoid using paresthesia to indicate spontaneous sensations and dysesthesia to
refer to evoked sensations. There is a sense in which, since paresthesia refers
to abnormal sensations in general, it might include dysesthesia, but the
reverse is not true. Dysesthesia does not include all abnormal sensations, but
only those that are unpleasant.
Pain along the distribution of one or more sensory nerve roots.
A disturbance of function or pathologic change in one or more nerve roots.
Inflammation of one or more nerve roots. This term does not apply unless
inflammation is present.
Derived from Greek word for "body," somatosensory input refers to sensory
signals from all tissues of the body including skin, viscera, muscles, and
joints. However, somatic usually refers to input from body tissue other than
viscera.
A state of emotional distress associated with events that threaten the
biological and/or psychosocial integrity of the individual. Suffering often
accompanies severe pain but, of course, it can occur in its absence; hence pain and suffering are phenomenologically distinct.
A hypersensitive area or site in muscle or connective tissue, usually
associated with myofascial pain syndromes.
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