Chapter 35 Complex regional pain syndrome.

B. As established by the International Association for the Study of Pain in 1994, the current recommended nomenclature is Chronic Regional Pain Syndrome (CRPS) Type I and Type II. Type I develops after an initiating noxious event, and Type II develops after a nerve injury. Complex regional pain syndrome Type I corresponds to Reflex Sympathetic Dystrophy (RSD) in that it does not have an identifiable nerve lesion. Type II designates causalgia, which presents similarly but occurs with injury to the peripheral nerve or its branch. Within the CRPS categories pain is regarded as sympathetically independent pain (SIP) occurring in the initial onset of the syndrome. Sympathetically maintained pain (SMP) is defined as "a symptom of CRPS and not a clinical entity” occurring after a period of time of the onset of the syndrome. CRPS has strict inclusion criteria that do not encompass the presence or absence of SMP. The international Association for the Study of Pain diagnostic criteria for CRPS are listed in the box below. Also, the pain can be described as sympathetically maintained (SMP) or sympathetically independent (SIP) based on the response to treatment to the sympathetic system. (Figure 1A-C)