In 1949, Steinbroker¹⁴ provided the first documentation of utilizing a pressure gauge to measure palpation forces for the purposes of physical diagnosis. The term “algometer,” however, wasn't coined until 1954 by Head and Keele.⁶ Algometers, sometimes referred to as "dolorimeters," "palpameters," "algesiometers," or "pressure threshold meters" are designed to quantify and document levels of tenderness via pressure threshold measurement and pain sensitivity via pain tolerance measurement. An algometer is essentially a very sensitive force gauge (mechanical or digital) designed to measure forces applied to very specific locations on the patient. Its tip generally ranges between .5cm² and 2cm². Results are typically reported in terms of pressure.

Pressure threshold is defined as the minimum pressure (force) required to cause pain. Pressure threshold measurements are usually performed over areas of muscle tenderness (sometimes referred to as trigger points). Normal data for male and females have been determined for many muscles in which trigger points are frequently found¹. Side-to-side comparison is also of significance when evaluating the results of testing.¹

Pressure tolerance is defined as the highest pressure (force) which can be tolerated under clinical conditions. Pressure tolerance measurements are typically performed over normal muscle and bone. Normal pressure tolerance data for males and females has been determined⁴.

Many clinical applications of the algometer have been documented, including evaluation of fibrositis¹² and fibromyalgia¹⁶, identification of trigger points², quantification of joint tenderness in arthritis conditions^5,8,11, evaluation of pain sensitivity^1,6, abdominal pain¹⁷, and in psychological research¹⁰. Pressure measurement has also been shown effective for evaluating the results of pain relieving modalities such as anesthetic blocks, heat, manipulation, anti-inflammatories, and for documenting the long-term effectiveness of treatment^1,9. Because of its reliability and reproducibility, algometry can be used for objective medico-legal documentation of pain intensity³

Algometry References

1. Fischer AA: Pressure algometry over normal muscles. Standard values, validity, and reproducibility of pressure threshold. Pain 1987;30:115-126.
2. Fischer AA. Documentation of myofascial trigger points. Arch Phys Med Rehab 1988;69:286-291.
3. Fischer AA. Pressure Threshold Meter: Its use for quantification of tender spots. Arch Phys Med Rehab 1986;67:836-838.
4. Fischer AA. Manual for Pressure Threshold and Tolerance Measurement, 1986 Great Neck, NY
5. Hollander JL, Young DG. Palpameter: instrument for quantification of joint tenderness. Arthritis Rheum 1963;6:277.
6. Keele KD. Pain sensitivity tests: pressure algometer. Lancet 1954;1:636-639.
7. Lansbury J. Methods for evaluating rheumatoid arthritis. In Hollander JL (ed): Arthritis and Allied Conditions: Textbook of Rheumatology, ed 7. Philadelphia, Lea & Febiger, 1966:269-291.
8. McCarthy DJ Jr, et al. Dolorimeter for quantification of articular tenderness. Arthritis Rheum 1965;8:551-559.
9. Merskey H, Spear FG. Reliability of pressure algometer. Br. J. Soc Clin Psychol;3:130-136
10. Merskey H., et al. Clinical investigation of reactions to pain. J Ment Sci 1962;108:347-355.
11. Moldofsky H, Chester W.J, Pain and mood patterns in patients with rheumatoid arthritis: prospective study. Psychosom Med 1970;32:309-318.
12. Moldofsky H, et al. Musculoskeletal symptoms and non-REM sleep disturbance in patients with "fibrositis syndrome" and healthy subjects. Psychosom Med 1975;37:341-351.
13. Reeves JL, et al. Reliability of the pressure algometer as a measure of myofascial trigger point sensitivity. Pain 1986;24:313 - 321.
14. Steinbroker O. Simple pressure gauge for measured palpation in physical diagnosis and therapy. Arch Phys Med;30:389-390
15. Travell JG, Simons DG. Myofascial Pain and Dysfunction: Trigger Point Manual. Baltimore MD 1983, Williams & Wilkins.
16. Tunks E, et al. Tender points in fibromyalgia. Pain 1988;34:11-19.
17. Yamagata S, et al. Diagnostic re-evaluation of electric skin resistance, skin temperature, and deeper tenderness in patients with abdominal pain. Tohuku J Exp Med 1976;118[Suppl]:183-189.