TABLE 1.
Taxonomy of pain stimuli and associated examples
| Pain Stimulus | Definition | Examples |
|---|---|---|
| Acute noxious stimulus | Able to produce tissue damage | Thermal-radiant heat |
| Mechanical-pressure | ||
| Chemical-acid | ||
| Inflammatory ± evocative acute stimulusa | Activates or mimics local or systemic inflammatory processes | CFA Carrageenan |
| Surgical Incision | ||
| Neuropathic ± evocative acute stimulusa | Damages peripheral sensory neurons or central neurons | Nerve ligation or constriction |
| Chemotherapy | ||
| Disease state ± evocative acute stimulusa | Diabetes (e.g., streptozocin treatment) | |
| Bone cancer (e.g., cancer cell injection to bone marrow) | ||
| Migraine (e.g., glycerol trinitrate injection) | ||
| Natural disease (e.g., arthritis in companion animals) |
a
Models of inflammatory, neuropathic, or disease-state pain often involve two stimuli: one to produce a relatively sustained state of inflammation, neuropathy, or disease-like pathology, and a second acute stimulus. The second stimulus is usually thermal or mechanical in modality and may range from innocuous to noxious in intensity. In subjects with inflammation/neuropathy/disease, the second acute stimulus may elicit pain behavior suggestive of “allodynia” (pain response to a normally innocuous stimulus) or “hyperalgesia” (hyperactive response to a normally noxious stimulus).