What is Pain?
is an unpleasant sensation
that can range from a mild, localized discomfort to
agonizing pain that is localized or spread out.
Pain has both a physical and an emotional
component. The physical part of pain results from
stimulation of the nervous system. Pain may be
contained to a discrete area, as in a specific
injury such as a back sprain or it may be a diffuse
pain as in fibromyalgia. Pain is mediated by
specific nerve fibers that carry the pain impulses
to the brain where their conscious appreciation may
be modified by a multitude of factors.
Acute pain is pain that comes on quickly, can be
severe, but lasts a relatively short period of
time. Pain that lasts longer than 90 days would be
considered chronic pain.
Chronic pain is defined as pain that lasts
longer than 3 months. However, some experts define
it as lasting longer than 6 months. Chronic pain is
in that it is often difficult to find the cause.
The medical diagnosis may reveal no injury in the
body at all, and yet the patient can be experiencing
very debilitating pain.
One way that chronic pain begins is from an
injury. Scientists have found that repeated pain
from an acute injury changes the way the brain
perceives that you know you have pain. Even after
the acute injury has healed, pain messages can often
replay over and over again in the brain.
Used In Pain Management
Pain due to a stimulus which does not normally
Absence of pain in response to stimulation which
would normally be painful.
Complex Regional Pain Syndrome I:
CRPS I formerly known as reflex sympathetic
dystrophy, consists of continuous pain (allodynia or
hyperalgesia) in part of an extremity after trauma
including fractures. However, the pain does not
correspond to the distribution of a single
peripheral nerve. The pain is worse with movement
and associated with sympathetic hyperactivity. The
patient often complains of cool, clammy skin which
later becomes pale, cold, stiff and atrophied. This
process often occurs within weeks of trauma, which
may be mild.
Complex Regional Pain
CRPS 2 formerly known as causalgia, consists of
burning pain in the distribution of a partially
damaged peripheral nerve (most commonly median,
ulnar or sciatic). Pain may occur within a month of
injury and may radiate beyond the nerve’s
distribution. The condition results from abnormal
sweat and vasomotor sympathetic efferent pathways,
possibly due to abnormal connections between
efferent sympathetic fibers and somatic sensory
fibers at the injury site. The skin is classically
cold, moist and swollen, becoming atrophic later.
Central pain: Pain initiated or
caused by a primary lesion or dysfunction in the
central nervous system.
An unpleasant abnormal sensation, whether
spontaneous or evoked.
An increased response to a stimulus which is
Increased sensitivity to stimulation, excluding the
A painful syndrome characterized by an abnormally
painful reaction to a stimulus, especially a
repetitive stimulus, as well as an increased
Diminished pain in response to a normally painful
Decreased sensitivity to stimulation, excluding the
Pain in the distribution of a nerve or nerves.
Inflammation of a nerve or nerves.
Pain initiated or caused by a primary lesion or
dysfunction in the nervous system.
A disturbance of function or pathological change in
a nerve: in one nerve, mononeuropathy; in several
nerves, mononeuropathy multiplex; if diffuse and
A receptor preferentially sensitive to a noxious
stimulus or to a stimulus which would become noxious
A noxious stimulus is one which is damaging to
The least experience of pain which a subject can
Pain tolerance level:
The greatest level of pain which a subject is
prepared to tolerate.
An abnormal sensation, whether spontaneous or
Peripheral neuropathic pain: Pain
initiated or caused by a primary lesion or
dysfunction in the peripheral nervous