A Virtual Pocket Dictionary of Pain Terms
Algology.
The science and study of pain phenomena. An algologist is a student, investigator, or
practitioner of
algology.
Allodynia.
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.
Analgesia.
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.
Anesthesia.
Absence of all sensory modalities.
Anesthetic.
Agent/agents that produce regional anesthesia (i.e., in one part of the body) or general
anesthesia (loss
of consciousness).
Anesthesia Dolorosa.
Pain in an area or region that is anesthetic.
Angina.
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.
Arthralgia.
Pain in a joint, usually due to arthritis or arthropathy.
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 associated with a lesion of the central nervous system.
Deafferentation Pain.
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.
Dermatome.
The sensory segmental supply to the skin and subcutaneous tissue.
Dysesthesia.
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.
Hyperesthesia.
Increased sensitivity to stimulation, excluding special senses.
Hyperalgesia.
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.
Hyperpathia.
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.
Hypoalgesia.
Diminished sensitivity to noxious stimulation.
Hypoesthesia.
Diminished sensitivity to stimulation, excluding special senses.
Neuralgia.
Pain in distribution of nerve or nerves.
Neuritis.
Inflammation of a nerve or nerves.
Neuropathic Pain.
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.
Neuropathy.
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.
Nociceptor.
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.
Noxious Stimulus.
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).
Pain.
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.
Pain Threshold.
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.
Pain Tolerance Level.
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.
Paresthesia.
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.
Radiculalgia.
Pain along the distribution of one or more sensory nerve roots.
Radiculopathy.
A disturbance of function or pathologic change in one or more nerve roots.
Radiculitis.
Inflammation of one or more nerve roots. This term does not apply unless inflammation is
present.
Somatosensory.
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.
Suffering.
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 can occur in its
absence; hence
pain and suffering are phenomenologically distinct.
Trigger Point.
A hypersensitive area or site in muscle or connective tissue, usually associated with
myofascial pain
syndromes.
For additional information:
IASP Secretariat
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Seattle, WA 98105-6020, USA
Tel: 206-547-6409
Fax: 206-547-1703
Email: IASP@locke.hs.washington.edu
WWW: http://www.halcyon.com/iasp
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This page was updated on May 24, 1999.