Salcido R, Musick DW, Erdman F: Erdman therapy: A treatment utilizing hot and cold therapy. Am J Phys Med Rehabil 2003;82:972–978.
Applying therapeutic heat and cold is a common practice in physical medicine and rehabilitation. 1–3 Despite its widespread use, however, relatively little is understood empirically or theoretically about why certain patients benefit from either hot or cold therapy for acute ailments or chronic conditions. 4 Lacking an evidence base, hot and cold therapy is mostly a trial-and-error process. The medical literature reveals that therapeutic heat and cold has been used to treat a variety of clinical conditions, most notably with patients suffering sports-related injuries and arthritic conditions (e.g., rheumatoid arthritis) and joint disorders (e.g., neck, back pain). 5–9 Recognizing in advance who would benefit from which modality, and who might be harmed, would represent a major step forward in understanding the mechanism and efficacy of therapeutic heat and cold.
An obscure, virtually unknown therapy in use for almost a century—known as the Erdman therapy—may yield insight into why some patients are helped by therapeutic heat and cold modalities. The basic premise of the Erdman therapy hypothesizes that patient groups respond to heat vs. cold therapy on the basis of arterial “tone”—the elastic qualities of the smooth muscles in the vessel walls. Arterial tone, in turn, heavily influences the rate of blood flow, and practitioners of this therapy consider blood flow the primary factor in maintaining good health. Using measurements of the rate of blood flow and arterial tone, the Erdman therapy suggests that the use of therapeutic heat and cold can be used to relieve discomfort and even reverse certain illnesses and conditions. Based on use of this therapy by trained practitioners, it is estimated that between 5% and 10% of the general population responds best to cold therapy and the rest to heat therapy. Practitioners have developed an indicator device—the Erdman indicator—to identify the two classes of patients. The theory supporting the categorization structure and its practical application has not been scientifically proven using traditional strength of evidence ratings. However, as in most therapeutic customs in medicine, we often provide care such as therapeutic hot and cold, massage therapy, and other physical modalities based on anecdotal experience rather than scientific evidence, while simultaneously striving for empirically oriented evidence for treatment efficacy. Within the context of complementary and alternative medicine today, the Erdman therapy is a historical example of this approach. With a continuing stream of patients for >90 yrs, accompanied by anecdotal evidence from patients and those who have cared for them, the Erdman therapy is a therapeutic modality worthy of a strength of evidence rating of “C” under current evidence rating schema. 10 The purpose of this article is 2-fold: first, to call attention to this therapy and its historical significance to the field of physiatry and, second, to stimulate further research into its efficacy in hopes of extending its use for patients who may benefit from it.
From the University of Pennsylvania School of Medicine, Rehabilitation Medicine, Philadelphia, Pennsylvania.
All correspondence and requests for reprints should be addressed to Richard Salcido, University of Pennsylvania School of Medicine, Rehabilitation Medicine, 5 West Gates Bldg., 3400 Spruce Street, Philadelphia, PA 19104-4283.