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Pain is a complex multidimensional symptom. It is determined
not only by actual or potential tissue injury and normal and abnormal
activity of the nervous system, but also by the patient’s
personal beliefs, mood, previous painful experiences, psychosocial
stressors, coping mechanisms, and motivational factors. Evaluation
of a patient with chronic pain should take into consideration all
of these factors. Unfortunately, there is no single test or scale
that can measure pain comprehensively, reliably, or objectively.
Thus, assessment of pain requires a thorough history and physical
examination in combination with other diagnostic tools. Several
visits may be required to elucidate relevant medical and pyschosocial
factors. The patient’s motivation for the evaluation must
be clarified early (i.e., whether there are issues of litigation
or disability affecting the patient’s pain, and whether
he or she perceives the potential to control pain as coming from
without or within). To do this, it is important to listen well and
not overly structure the interview. Chronic pain patients need validation.
Without it, they cannot offer their trust, and trust is vital for treatment
compliance and a successful outcome.
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Pain assessment is a dynamic process that evolves with the pain
management plan. The pain evaluation should be used to localize
the source of pain; to determine its quality, pattern, and intensity;
to define exacerbating and attenuating factors; and to assess how
environmental and behavioral influences affect the pain. Clinicians
should always try to make a diagnosis before implementing a treatment
plan, recognizing that jumping to a premature conclusion might result in
inappropriate treatment or harm to the patient. It is also necessary,
at times, to rethink the diagnosis, despite previous and thorough
workups.
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Pain should be broadly defined as nociceptive (somatic or visceral),
neuropathic, or idiopathic. Toward this end, pain location is of
utmost importance to accurate diagnosis. It may be well localized,
as in entrapment neuropathy (e.g., carpal tunnel syndrome), widespread
and diffuse (e.g., fibromyalgia), or regional (e.g., musculoskeletal
pain). Patterns of radiation may help determine the site of pathology,
such as in cervical or lumbar radiculopathy. Radicular pain (along
a dermatome) implies involvement of a nerve root. Pain may also
be referred, as in visceral pain, when it is felt over a particular
area of skin that is embryologically associated with but anatomically
distant from the source of irritation. Accurate characterization
of the pain’s location and pathophysiology provides the
rationale for treatment. Tables 6-1, 6-2, and 6-3 provide examples
of referred pain contrasted with clinical findings associated with
nerve root versus peripheral nerve pathology.
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