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Four
elements can strengthen the clinician's or investigator's etiological
certainty for a particular symptom:
- An established
causal mechanism;
- Objective
findings on physical examination or diagnostic testing;
- Responsiveness
to a specific treatment; and
- A single
(rather than multifactorial) cause (Kroenke,
2001).
Examples of
such "higher certainty" causes include angina pectoris
as the basis for a patient's chest pain, peptic ulcer disease
producing epigastric pain, atrial tachycardia resulting in palpitations,
and asthma-related dyspnea.
Lower certainty
causes constitute a spectrum. At the broadest level, clinicians
and investigators may simply classify a symptom as physical, psychiatric,
or idiopathic (functional) in origin (Khan
et al., 2000; Kroenke
and Mangelsdorff, 1989). Although crude, this tripartite classification
is sometimes the only level of specificity that can be attained.
Within this
tripartite classification there may be intermediate levels of
uncertainty. For example, dizziness may be categorized as vertigo
-- a discrete type of sensation that usually denotes a vestibular
etiology but with multiple possible specific and nonspecific causes
-- or back pain may be categorized as mechanical.
Sometimes,
a symptom may be categorized by what it is not, such as noncardiac
chest pain or nonulcer dyspepsia.
Also, as mentioned
previously, there are a variety of symptom syndromes -- irritable
bowel syndrome, fibromyalgia, chronic fatigue syndrome, temporomandibular
joint disorder, tension headache, and others - that consist entirely
of symptoms or symptom complexes for which the exact etiology
remains unclear.
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