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The degree
of pain sensed is proportional to the number and strength of
the signals sent, which in turn is an indicator of the
intensity of the originating noxious stimulus. The specific
detection mechanisms upon which certain proteins consider
any type of stimuli to be “noxious,” remain a mystery to
science (Caterina & Julius, 2001). While this process of
pain sensation is well researched and widely held as true,
it is not to be equivocated as the exclusive mechanism upon
which pain is felt. In the issue of chronic, psychogenic,
and phantom pain, no specific nociceptive mechanism may be
present, since the localized region may be completely free
from tissue damage. Yet even so, the patient may still
report intense pain from the region, leading some to
theorize that ultimately the brain itself may be responsible
for the generation of pain (Bloom, Nelson, & Lazerson,
2001). The true answer is most likely to be somewhere in
between, namely that some pain has a physical, electrical
origin via nociceptors that traverse a specified pain
pathway throughout the central nervous system, and other
types of pain may have both origin and destination
completely within the brain itself.
Nociceptive Pain
This is the
protective type of pain that most people are accustomed.
The level of pain usually correlates well to the level of
noxious stimuli. Nociceptive pain is the normative
expectant result from tissue damage or harm, such as
sprains, inflammation, sickness, and injury. The key
factor to defining nociceptive pain is that it dissipates
upon the restoration of the affected area. Namely, when
healing occurs, the pain goes away.
Neuropathic Pain
Neuropathic pain is a
sensation of pain that originates from within the nervous
system, rather than an external source. It can be either
chronic or acute, and frequently does not respond well to
opioids (Wentz, 2003).
It is the most difficult type of pain to treat, as it is not
fully understood. This type of pain is generally described
as a tingling, stinging, or burning sensation and can have
all degrees of severity. In general, it is thought that
neuropathic pain serves no defensive purpose, often
following a trauma, infection, or illness. The pain may
persist in various forms throughout life, never fully going
away. Peripheral neuropathic pain begins in the extremities
and often migrates up the limbs. Because the unique
mechanism in each patient diagnosed with neuropathic pain is
difficult to identify, dealing with it often is a process of
trial and error.
Increased pain from stimuli
that ordinarily produces lower levels of pain, known as
hyperalgesia is considered a symptom of neuropathic pain. A
similar condition, allodynia, is undergoing a severe pain
response from nonpainful stimuli. Phantom pain normally
referred to as the discomfort of one who has undergone an
amputation with the feeling of pain in the missing limb, is
another type of neuropathic pain. Some types of cancer
pain, peripheral neuropathy and causalgia, among others, all
contribute to the spectrum of neuropathic pain. While the
precise mechanisms of these kinds of pain are uncertain,
they are clinically recognized as real pain with a medical
basis, rather than psychosomatic or imagined.
Idiopathic Pain
Idiopathic pain is generally referred to as real
pain with a foundational basis in psychogenic factors. The
underlying cause may be completely unknown, but is usually
assumed to have a basis in the functioning of the brain
itself. In some patients, there is no evidence of
an associated organic cause, whereas in others, pain and
associated symptoms are out of proportion to identifiable
organic pathology (Lehmann, 1998).
This type of pain may both
originate and terminate strictly within the brain, though
its true cause is still in dispute. Examples include
myofacial pain syndrome and somatoform disorder.
Chronic and Acute Pain
Chronic pain is defined as
prolonged pain lasting at least six months. It can be
neuropathic, idiopathic, or nociceptive, or a combination of
all three. It is a “multidimensional experience with
sensory, affective, cognitive evaluative components, each of
which interacts and contributes to the final pain response”
(Galises & Melzack, 1997). Chronic pain is currently
becoming recognized as a primary issue unto itself, rather
than a symptom of an underlying problem. Chronic pain
sufferers are more dependent upon processes of pain
management, rather than constantly seeking for a ‘cure’.
Learning to manage the pain over the course of the lifespan
represents the greatest chance one with chronic pain has to
enjoy a fulfilling life, as complete healing may never come.
Where
chronic pain is often difficult to fully understand, and can
have unknown or various causes, acute pain is usually
nociceptive and correlates to identifiable noxious stimuli.
This type of pain is considered temporary and treatable and
results from physical damage to the body. Unlike chronic
pain, treatment for acute pain deals with the direct
underlying cause. In some cases, acute pain can lead to
chronic pain. Ekman and Koman (2004) warn that inadequate
treatment of acute pain can eventually result in chronic
pain due to the desensitization of the peripheral and
central nervous system.
Psychology
and the Pain Pathway
The
psychology of the patient plays a crucial role in the
individual experience of pain. The intensity, duration, and
degree of disruption of pain bind fundamentally to the
emotional and psychological state of the individual
experiencing it. In addition, these beliefs also influence
the process of pain management. In recent studies with
cancer patients (Dawson, et. al., 2005), individuals were
asked, over a period of time, to rate their pain experiences
using subjective scales of one to ten to correlate with the
intensity of suffering. Later, these patients were asked
evaluative questions pertaining to their personal beliefs
about pain and treatments for pain. Conclusions indicated a
relationship with the effectiveness of the pain management
process to the beliefs and concerns of the patients
governing pain. For example, those who lacked high school
education were more likely to interpret pain as having
direct correlation to the severity of the physical
condition; hence, to experience a bout of sudden severe pain
could cause a lot of fear since that meant the physical
condition was drastically worsening. This fear, in turn,
can exacerbate the original pain, making it more intense,
hence causing the patient to rate the overall experience
higher on the one to ten scale than it would have been
otherwise.
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