There are two types of CRPS - CRPS I and II.
- Type I CRPS (formerly known as reflex sympathetic dystrophy) is characterized by the development of neuropathic pain after tissue trauma (ex. surgery, bone fracture).
- Type II CRPS (previously known as causalgia) results from injury to a peripheral nerve, the pain extending beyond the distribution of the injured nerve.
The fundamental difference between the two disorders is the presence of a clinically verified nerve injury in patients with type II CRPS. Both manifestations of the disorder are characterized by symmetric sweating, changes in skin texture, diminished skin temperature and swelling.
The illness may be associated with minor or major injuries. Without history of significant trauma, the patient may appear disproportionately disabled, frequently with startling loss of range of motion if an extremity is affected. If the patient had undergone a surgery, a protracted recovery period during which the patient poorly tolerated all rehabilitative efforts is a common feature.
CRPS tends to affect the extremity in most cases. It starts elsewhere and may spread to other regions of the body. It can affect adults and children as well. In general, the prognosis in children is favourable. Approximately 10% of the population referred to pain centers in USA, are referred for CRPS I. Several studies have suggested incidences of CRPS II to be between 2-14% after peripheral nerve injury. CRPS is more common in women than men (3:1). Adolescent girls are affected more than boys. Lower limb is more affected than upper limb.